Publisher：Lithos  

There are a few intrusive bodies in the central Sanandaj-Sirjan Zone (C-SaSZ), which is parallel to the Zagros suture zone, in western Iran. The Alvand batholith in the Hamedan area is one of these bodies and consists of rock types with large variation, in particular, two-mica garnet-bearing granite with an S-type signature. Zircon U[sbnd]Pb dating gives crystallization ages of 170–163 Ma for the S-type granite. The 176Hf/177Hf ratios in the zircon grains vary from 0.282001 to 0.282780 (rim), with low 176Lu/177Hf ratios (0.002 to 0.018). The εHf(t) values (rim) are clustered into two main groups: a negative εHf(t) group (−6.9 to 0.0, n = 39), with some highly negative εHf(t) values (−25.8 to −21.9, n = 3), and slightly positive εHf(t) values (+0.3 to +2.9, n = 14) of inherited grains. The δ18O values for the zircon grains are positive and range from +10.4‰ to +11.8‰. The high δ18O (positive) and mostly negative εHf(t) values are more consistent with continental crustal sources for these rocks, and the Hf model ages (TDM2) show a wide range from 2.7 to 0.8 Ga, suggesting the heterogeneity of the crustal components. The long incubation time (2089 to 544 Ma) indicates a long history of crustal residence and crustal reworking. The incubation age of the zircon grains, >300 Ma, confirms the recycling of crustal material by partial melting. The simultaneous occurrence of S-type granites with mafic bodies, such as gabbro and diorite members with tholeiitic signatures, suggests that the injection of mafic magma increased the geothermal gradient from the bottom and sides along the major faults, which was the trajectory for the injection of hot mafic melts to shallow depths. These processes abnormally increased the geothermal gradients locally, and the partial melting of crustal and supracrustal materials produced S-type granites and migmatization among the hot blade-shaped mafic bodies. Therefore, the partial melting of crustal material in an extensional tectonic regime and/or in a thin continental crust occurred in a continental rift and/or in the Neo-Tethys passive margin. The present work concludes that the passive margin can be suggested as the tectonic setting for the generation of S-type granites, without the collisional regime that has been widely considered for the sources of this type of granite in the world.

DOI： 10.1016/j.lithos.2023.107437

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Concrete Institute  

<p>Capturing atmospheric CO₂ into cement-based materials is a way to set off the CO₂ emissions of concrete production. This study proposes an experimental method to track the origin of cement paste that fixes CO₂ directly from the air under natural conditions. By exposing powders of well-hydrated cement paste to air, carbonated cement paste powders are obtained with different carbonation degrees. The inorganic carbon of these carbonated samples is extracted by dissolution in phosphoric acid, and the isotopic characteristics related to ¹³C and ¹⁴C are measured. The experimental results show that the ¹⁴C value of carbonated cement paste can be used as an indicator for tracing the origin of carbon.</p>

DOI： 10.3151/jact.21.934

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Environmental Monitoring and Assessment  

Karaftu Cave in the northwest of Divandareh includes four floors plus an underground area. The bat hall and its underground area are covered with guano deposits. 14C dating indicates the onset of guano deposition is about 14,260±50 BP years, and its average accumulation rate is about 4.1 mm/yr for depths of 360 to 205 cm. Bacterial and fungal metabolisms decay guano, release acids, and disperse large amounts of microorganisms inside the cave. Interactions between acids and guano caused leaching, dissolution, change in the distribution, and abundance of elements, which leads to the formation of secondary minerals in guano. These variations in minerals and elements also depend on the local climatic conditions. Distribution of elements in the Ce/Ce* versus Pr/Pr* diagram and the correlation coefficient between Ce and Mn display three different paleoclimate conditions (dry, wet, and dry) during the accumulation of the guano. Also, dolomite, phosphate, and iron oxide minerals have been formed during the passage of water through bedrock beneath the guano. This water is unsuitable for drinking and harmful to the organisms in the region. Effect of these acids on the substrate also leads to the collapse of the cave floor, generation of a new underground, fall in the groundwater level, change in the groundwater drainage system, drying of springs around the cave, loss of green cover, and a negative impact on the ecosystem in the region. To keep the cave environment clean and remove these problems, it is better to harvest guano and use it as fertilizer.

DOI： 10.1007/s10661-023-11624-9

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PubMed

Publishing type：Research paper (scientific journal)   Publisher：Radiocarbon  

The article presents results of measurements of radiocarbon (14C) concentration in sub-annual dendrochronologically dated tree rings of English oak (Quercus robur L.) from Grabie village near Kraków (southern Poland). Samples of early wood (EW) and late wood (LW) spanning the years 664-658 BCE. α-cellulose was extracted from each sample and their radiocarbon content was measured at the ATOMKI laboratory in Debrecen, Hungary. The EW and LW data confirm a prolonged increase in "14C values around 665-663 as was observed by Park et al. (2017), Rakowski et al. (2019), or Sakurai et al. (2020). In addition, we found that this event may consist of two relatively small events, as was proposed by Sakurai et al. (2020). Based on obtained in this and previous study data we estimate that the occurrence of the two events were between 665 and 664 BCE (Rakowski et al. 2019), and in late spring of 663 BCE (May-June, before beginning of LW formation).

DOI： 10.1017/RDC.2023.79

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Petrology  

Several swarms of parallel E-W dikes cuts late Neoproterozoic- to early Paleozoic (540 Ma) basement in the Biarjmand area, NE Iran. The microgabbroic to doleritic dike are several hundred meters long and 0.5 to 3 meters wide. U-Pb dating of their zircon grains yields a crystallization age of 46.0 ± 7.1 Ma for the dike swarms. The dikes have SiO2 contents of 46.0-49.3 wt%, and Fe2O3 contents of 9.80-14.8 wt% with variable MgO (4.92-9.16 wt%), TiO2 (1.47-2.65 wt%), and K2O contents (0.33-1.13 wt%). The dikes have low contents of high field strength elements (HFSEs), and have some similarities to transitional mid-ocean ridge basalts (T-MORB) based on their chemical composition. Positive values of +5.2 to +6.0 for the dike samples imply that the basaltic magma was generated from depleted lithospheric mantle. After the closure of the Sabzevar ocean and obduction of the large mantle peridotite body over the continental crust in the late Cretaceous-Paleocene, the gravitational instability in the central Iran/Eurasia plate collision zone triggered exhumation of old basement coeval with injection of the mafic magma. During exhumation, mylonitic deformation with brittle-ductile structures affected the basement metagranite and the host rocks. The metagranite and dike swarms cut the Cretaceous Sabzevar ophiolite, and the disparting of ophiolite members probably occurred during basement exhumation in the Cenozoic. The similar ages of the mafic dike swarms and other Eocene magmatic rocks of the Urumiah (Urmia) Dokhtar magmatic arc (UDMA), western Iran, is consistent with a rapid extensional regime over the Sabzevar suture zone on an earlier collision zone in NE Iran. This process provided a suitable setting for the exhumation of the old basement, the emplacement of the parallel dike swarm, and the development of shallow basins in this area.

DOI： 10.1093/petrology/egad039

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Zoo and Wildlife Medicine  

<p>　Asian black bears (<i>Ursus thibetanus</i>) in Japan are clustered into 3 lineages (eastern, western, and southern clusters) based on mitochondrial DNA (mtDNA) haplotypes of an approximately 700 bp sequence in the D-loop region of mtDNA. In 2012 the Ministry of the Environment of Japan announced the Asian black bear population in Kyushu, the southwestern island of the Japanese archipelago, as locally extinct, because the last reliable record of the Asian black bear in Kyushu was in 1941. The number of samples and genetic analysis results pertaining to the Asian black bear population in Kyushu are very few. Therefore, the molecular phylogenetic characteristics of Asian black bears in Kyushu remain a missing link in understanding the trajectory of Asian black bear populations from the Asian mainland to Japan. In this study, we investigated the mtDNA haplotypes of Asian black bears in Kyushu using four old bone samples, which we found at various locations and dates. We succeeded in detecting two new haplotypes and a haplotype of the western cluster. The two new haplotypes also belonged to the western cluster. These results suggest a continuous distribution of Asian black bears between western Chugoku and Kyushu, and indicate that genetic variation occurred after habitat fragmentation. These results provide data to support the considerations of previous studies on the migration of Asian black bears from the Asian continent to the Japanese archipelago.</p>

DOI： 10.5686/jjzwm.28.35

DOI： 10.5686/jjzwm.28.35

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Geological Society of Japan  

<p>Numerous carbonate concretion samples were collected during dredging around Nagoya Port in the 1960s. Most of the samples contained biological remains, including crabs, sea urchins, and bivalves, which formed their nuclei. In this study, the radiocarbon (¹⁴C) ages of the shells of the biological remains inside the concretions, as well as of the concretions themselves, were determined. Based on the metabolic carbon ratios of the bivalvia and sea urchin shells, which were calculated using δ¹³C values, the ¹⁴C ages of the shells and those of the metabolic carbon were estimated to be 7,350-7,050 cal BP and 9,680-9,430 cal BP, respectively. The ¹⁴C ages of the carbonate concretions were older than those of the shells due to the addition of metabolic carbon with older ages to the carbon of the concretion. The corrected age after removal of the old carbon was estimated to be 7,530-7,270 cal BP. The near-identical corrected ages of the shells and concretions indicate that the carbonate concretions in the Nagoya Port area formed rapidly after the death of the organisms, which is consistent with morphological evidence of rapid concretion formation in the sediment.</p>

DOI： 10.5575/geosoc.2022.0021

CiNii Research

Publisher：Limnology and Oceanography: Methods  

This study aimed to assess whether benzalkonium chloride (BAC) addition to water samples could be used as a disinfectant in the radiocarbon (14C) analysis of dissolved inorganic carbon (DIC). We investigated the effectiveness of BAC addition in inhibiting 14C changes in DIC due to microbial activity during water preservation. The DIC and 14C concentration of natural waters (groundwater, seawater, river water, and lake water) without BAC increased by 1.4–3.3 mg L−1 and 1.8–4.2 percent modern carbon (pMC) for 2 weeks, and 2.2–7.9 mg L−1 and 3.0–11.9 pMC for 4 weeks, respectively, while none of the BAC-treated water samples, excluding seawater, exhibited changes in DIC or 14C concentration. Although slight increases in DIC and 14C concentrations in seawater with BAC treatment were observed, 0.4 mg L−1 and 0.4 pMC for 2 weeks, and 1.6 mg L−1 and 1.5 pMC for 4 weeks, respectively, these changes were 20–40% lower than that in seawater without BAC treatment. Furthermore, carbon contamination into the sample water due to BAC decomposition and BAC-induced microorganism decomposition was negligible in 14C analysis, albeit using BAC solution without atmospheric CO2 contamination could be a significant issue. Our results demonstrate that BAC is an effective inhibitor of biological DIC changes for 14C analysis of freshwater samples, although slightly less effective in seawater.

DOI： 10.1002/lom3.10508

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Language：Japanese   Publisher：Lithos  

The Late Neoproterozoic basement is exposed in the Mahabad area of northwest Iran, and it is classified into three main groups. The first is metamorphic rocks that include gneiss, schist, phyllite, and slate. The second is sedimentary rocks, which comprise shale, sandstone, and dolomite and the third is igneous rocks including granite, rhyolite, felsic tuff, and ignimbrite, which are the subject of this research. Zircon U[sbnd]Pb ages for three igneous samples show that crystallization occurred at 558–552 Ma in the late Neoproterozoic (Ediacaran). The felsic magmatic rocks have SiO2 contents of 64.3 to 78.9 wt%, Al2O3 contents of 12.0 to 16.8 wt%, low TiO2 contents (0.08 to 0.69 wt%), and large variations in K2O (0.05 to 5.46 wt%) and Na2O (1.17 to 6.70 wt%). The felsic magmatic rocks are enriched in light rare earth elements (REEs) such as La and Sm, have flat heavy REE patterns, and strong negative Eu anomalies. They are mainly weakly to strongly peraluminous and calc-alkalic to alkali-calcic rocks. A wide range of initial 87Sr/86Sr(556Ma) ratios (0.7056 to 0.7203) and negative εNd(t) values (−6.0 to −2.9) do not show clear trends of mixing/contamination among mantle, slab fluids, and/or altered oceanic crust. The Mahabad magmatic rocks were produced mainly by partial melting of graywacke, psammite, and shale at high temperatures (~800 °C), based on the zircon saturation index. S-type like granites usually form in syn- to post-collisional systems, but the Mahabad felsic rocks, which have almost the same ages as the associated sedimentary rocks, were generated in an extensional regime according to geochemical discrimination diagrams. This can be explained as follows: sediments were deeply buried during the late Neoproterozoic amalgamation of microcontinents at a subduction zone along the northern boundary of Gondwana, and then erosion of the roof and/or thinning owing to extension led to upwelling of the asthenosphere and intrusion of mafic magma, which was responsible for partially melting the buried metasedimentary rocks to generate S-type like granites and felsic volcanic rocks.

DOI： 10.1016/j.lithos.2022.106658

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.sedgeo.2021.106075

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Language：Japanese  

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>To understand seawater properties, such as water mass structure and mixing, geochemical analyses are useful. However, geochemical datasets for seawater that fully cover coastal areas of Hokkaido, North Japan are lacking. Here we report comprehensive geochemical analyses of seawater (salinity, δ¹⁸O, δD, and Δ¹⁴C) collected in August–September 2021 from coastal areas of Hokkaido as well as the west coast of Tohoku (Northeast Japan). These datasets are expected to improve our understanding of seawater properties around Hokkaido, thereby contributing to oceanography, climatology, biogeochemical cycles, and fishery science.</p>

DOI： 10.2343/geochemj.GJ22021

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Language：Japanese   Publisher：Communications Earth and Environment  

The hadal zone at trenches is a unique region where forearc mantle rocks are directly exposed at the ocean floor owing to tectonic erosion. Circulation of seawater in the mantle rock induces carbonate precipitation within the deep-sea forearc mantle, but the timescale and rates of the circulation are unclear. Here we investigated a peculiar occurrence of calcium carbonate (aragonite) in forearc mantle rocks recovered from ~6400 m water depth in the Izu–Ogasawara Trench. On the basis of microtextures, strontium–carbon–oxygen isotope geochemistry, and radiocarbon analysis, we found that the aragonite is sourced from seawater that accumulated for more than 42,000 years. Aragonite precipitation is triggered by episodic rupture events that expel the accumulated fluids at 10−2–10−1 m s−1 and which continue for a few decades at most. We suggest that the recycling of subducted seawater from the shallowest forearc mantle influences carbon transport from the surface to Earth’s interior.

DOI： 10.1038/s43247-021-00317-1

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Language：Japanese   Publisher：Lithos  

Late Neoproterozoic basement of the Soursat complex to the southeast of Shahin-Dej, NW Iran, spans an area wider than 100 km2 and is cut by Paleogene monzonite and granodiorite bodies. Zircon U-Pb dating yields monzonite and granodiorite crystallization ages of 54.7 ± 3.8 Ma and 57.7 ± 2.9 Ma, respectively. The monzonite group has relatively high MgO (2.40–7.01 wt%), Cr (37.5–233 ppm) and Ni (30.6–177 ppm), and high Sr/Y (103−132) and La/Yb (68.0–102) similar to low silica-adakites (LSA). The granodiorite group has low MgO (<1 wt%), Ni (<10 ppm) and Cr (<33 ppm), and high Sr/Y (192–361) and La/Yb (37.3–156) ratios, and are consistent as high silica-adakites (HSA). The monzonite and granodiorite have 87Sr/86Sr(i) values of 0.7045 to 0.7047 and 0.7053 to 0.7058, and εNd(t) values of +1.1 to +1.8 and − 1.9 to −0.8, respectively. The differing chemical compositions and Sr-Nd isotope ratios of these two groups of coeval adakites suggest different sources. Upon consideration of the geodynamic evolution of NW-Iran during the Cenozoic, we infer a two-stage melting process. LSA melts were first produced due to partial melting of delaminated lithosphere and then modified by fractional crystallization in the lower crust. Subsequently, HSA melts were generated during partial melting of lower crustal mafic segments in the hot root zone.

DOI： 10.1016/j.lithos.2021.106438

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Language：Japanese   Publisher：Radiocarbon  

Tsunamis are huge disasters that can significantly damage benthic organisms and the sea-bottom environment in coastal areas. It is of great ecological importance to understand how benthic ecosystems respond to such destructive forces and how individual species are affected. Investigating the effect of such disasters on animals that are seldom caught alive is particularly difficult. Bivalve mollusks are especially suitable for investigating how a tsunami affects coastal benthic species because they preserve an environmental record in their shells that can be extended back in time by crossdating the records of multiple individuals. Here we studied dead shells of Mercenaria stimpsoni, a long-lived clam, and precisely determined the time of death by using nuclear bomb-induced radiocarbon (bomb-14C) and by counting annual growth increments. First, a quasi-continuous, regional bomb-14C record was created by analyzing the shells of 6 live-caught M. stimpsoni individuals. Then 27 dead shells collected from the seafloor of Funakoshi Bay were 14C-dated and analyzed. The results showed that the huge tsunami that struck northeastern Japan on 11 March 2011 caused mass mortality of this bivalve in Funakoshi Bay. Nine of the 27 clams died during the March 2011 tsunami, probably by starvation after burial by tsunami deposits or exposure above the seafloor as a result of sediment liquefaction during the earthquake. The dating method used in this study can help us understand how long-lived marine organisms with low population density are affected by huge natural disasters such as a tsunami.

DOI： 10.1017/RDC.2021.98

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Language：Japanese   Publisher：Radiocarbon  

We developed a simple and cost-effective method for extracting carbon from dissolved inorganic carbon (DIC) in water samples without a carrier gas. This method only slightly modifies the existing vacuum line for CO2 purification in radiocarbon research laboratories by connecting several reservoirs and traps. The procedure consists of repeated cycles of CO2 extraction from water into the headspace of the reaction container, expansion of the extracted gas into the vacuum line, and cryogenic trapping of CO2. High CO2 yield (∼98%) was obtained from a variety of water samples with a wide range of DIC concentrations (0.4-100 mmol·L-1, in the case of 1.2 mgC). The δ13C fractionation depended on the CO2 yield, while the 14C concentration was constant within the error range, regardless of the CO2 yield. The average δ13C discrepancy between the results of this method and direct analyses made using the GC-IRMS was 0.02 ± 0.06‰. The standard deviations (1σ) in fraction of modern carbon (F14C) ranged from 0.0002 to 0.0004 for waters below 0.01 of F14C, and below 0.8% of F14C values for waters above 0.1. We conclude that this method is useful for effectively extracting CO2 from DIC in water and yields accurate 14C data.

DOI： 10.1017/RDC.2021.48

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DOI： 10.3390/min11070717

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1093/petrology/egab022

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Scientific Reports  

Isolated silica concretions in calcareous sediments have unique shapes and distinct sharp boundaries and are considered to form by diagenesis of biogenic siliceous grains. However, the details and rates of syngenetic formation of these spherical concretions are still not fully clear. Here we present a model for concretion growth by diffusion, with chemical buffering involving decomposition of organic matter leading to a pH change in the pore-water and preservation of residual bitumen cores in the concretions. The model is compatible with some pervasive silica precipitation. Based on the observed elemental distributions, C, N, S, bulk carbon isotope and carbon preference index (CPI) measurements of the silica-enriched concretions, bitumen cores and surrounding calcareous rocks, the rate of diffusive concretion growth during early diagenesis is shown using a diffusion-growth diagram. This approach reveals that ellipsoidal SiO2 concretions with a diameter of a few cm formed rapidly and the precipitated silica preserved the bitumen cores. Our work provides a generalized chemical buffering model involving organic matter that can explain the rapid syngenetic growth of other types of silica accumulation in calcareous sediments.

DOI： 10.1038/s41598-021-83651-w

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOC JAPAN  

The absolute date of the Millennium Eruption (ME) of Changbaishan Volcano is widely recognized as AD 946. The Baegdusan-Tomakomai (B-Tm) tephra dispersed during the ME is a robust-age key bed. In order to identify the tephra, refractive index and major- element compositions of volcanic glass shards are conventionally used. Meanwhile, traceelement analysis using the inductively coupled plasma mass spectrometry (ICP- MS) technique for the volcanic glass shards and bulk samples of the B- Tm tephra is still limited. Here we give a detailed description of major- and traceelement compositions for the glass shards and bulk sediments of the B-Tm and Towada caldera eruptions (To-a) tephra deposits from the Lake Ogawara sediment core, Tohoku region, northern Japan to identify the tephras. The depth profiles of the major and trace elements show the significant peaks for the K2O and some trace elements (Zn, Rb, Zr, Nb, Sn, Y, La, Ce, Nd, Th, and U) at the B-Tm tephra layer in the Lake Ogawara sediment core, but no peaks of these elements at the Toa tephra layer. High concentrations of the trace elements in the B- Tm tephra layer were observed in individual glass shards as well as in the bulk sediment. These concentrations are highlighted by the elemental abundance pattern normalized by the crustal abundance. The elemental pattern in individual glass shards from other Japanese tephras showed significant differences from those of the B-Tm tephra, especially in REE compositions. The trace-element compositions of the glass shards and bulk sediments show a strong tool for distinguishing the B-Tm tephra from other Japanese tephras.

DOI： 10.2343/geochemj.2.0619

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Language：Japanese   Publisher：Journal of Asian Earth Sciences  

Intrusive bodies with a wide-ranging geology are distributed in the central part of the Sanandaj-Sirjan zone (C–SaSZ) in southern Ghorveh, western Iran. The zircon U–Pb ages were dated at 154–146 Ma, and were characterized by low 87Sr/87Sr(i) ratios and high 143Nd/144Nd(i) ratios that ranged from 0.7035 to 0.7061 and 0.51245 to 0.51271, respectively (positive εNd(t) values). Magma differentiation and mixing formed different magmatic rocks that range widely from gabbro to granite in the Meiham–Shirvaneh area in southern Ghorveh. However, there was no clear evidence to support the slab role for the enrichment of large-ion lithophile elements (LILEs) and light rare–earth elements (LREEs) in this area. Meanwhile, there is a possibility that some ocean island basalt-like melt, which has been reported in the Ghorveh area for the same period, was involved in the minor enrichment of LILEs and LREEs. The high development of the released depleted mantle melts, with a minor role played by crustal components, accelerated the thinning of the continental crust in an extensional regime such as continental rift in the C–SaSZ during the Jurassic. This rift was responsible for the sequential injection of mafic magma with a wide range of magma mixing and mingling in southern Ghorveh during the Late Jurassic. As a result, we observed a wide range of intrusive rocks from gabbro to granite with different compositions, which included some clear mixing and hybrid textures. This finding demonstrated how the released mantle melt formed a thicker crust in western Iran.

DOI： 10.1016/j.jseaes.2020.104469

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Language：Japanese  

DOI： 10.1007/s00710-020-00705-z

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.sedgeo.2020.105664

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>Various granitoid bodies from the Neoproterozoic to Late Cenozoic intruded in the Sanandaj-Sirjan zone (SaSZ) in western Iran. In this research, we have compiled data for rare earth elements (REEs) concentration in the granitoid bodies which we have collected in the northern part of the SaSZ in this decade. The abundances of ∑REEs in a part of the granitoids are over 500 and even 2000 ppm. Although most of the granitoids such as Ebrahim Atar, Panjeh, Ghorveh, Kangareh, and Ghalaylan have low or normal values of ∑REEs and are not hopeful for future exploration, some hopeful bodies such as the Mobarak Abad granitoid in the east of Sanandaj and the Hassansalaran A-type granites in the east of Saqqez are recognized as REEs potential for future exploration. The chemical compositions of the REEs-enriched granites such as the Hassansalaran A-type and Mobarak Abad granites infer that the granites were generated in an extensional tectonic regime. Our finding shows that the granitic rocks which are related to the within plate tectonic setting in the SaSZ, NW Iran, can be considered as good potential for REEs exploration in the future.</p>

DOI： 10.2343/geochemj.2.0584

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1017/RDC.2019.104

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1017/RDC.2019.105

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DOI： 10.1017/RDC.2019.97

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

The preservation of unpoisoned water samples was investigated by radiocarbon analysis with five kinds of natural waters. Although refrigerated and shielded from light, the unpoisoned samples underwent carbon isotopic changes, even after short periods of storage (e.g., 5 days). Examinations of the isotopic changes during long-term preservation (580 or 860 days) revealed C-14 increases to be approximate 10 pMC and delta C-13 decreases to be - 5.4 parts per thousand. Performance tests on the sample bottles suggested that PAN (polyacrylonitrile) and glass were suitable materials for long-term preservation.

DOI： 10.1016/j.nimb.2018.11.029

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Language：Japanese   Publisher：The Geochemical Society of Japan  

<p>We have elucidated retention of primary Sr isotopic ratios in source rocks to sediments and sedimentary rocks during repeated sedimentation recycling. Twenty-three fine stream sediments (<180 μm) in Awajishima Island were used for the study. The ⁸⁷Rb/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr of stream sediments originated from Cretaceous Ryoke granitic rocks and Cretaceous sedimentary rocks (Izumi Group) were similar to those of the respective source rocks. Incidentally, the ⁸⁷Rb/⁸⁶Sr-⁸⁷Sr/⁸⁶Sr of stream sediments in Awajishima Island suggests that Cretaceous felsic igneous rocks are the dominant source of clastics in Izumi Group. Stream sediments derived from Neogene and Quaternary sediments, which are originated from granitic rocks and Izumi Group, had comparable isotopic ratios to those of the respective primitive source rocks. Accordingly, ⁸⁷Rb/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr can be retained during the repeated recycling process of sediments and sedimentary rocks. Stream sediment is presumed to consist of clastics supplied from respective lithologies according to their exposed areas. However, ⁸⁷Sr/⁸⁶Sr of stream sediment is not comparable to the values calculated from exposed areas of lithologies and isotopic data of parent rocks. The result suggests that amount of sedimentation denudation and production differs among different lithologies and is not simply proportional to their exposed areas.</p>

DOI： 10.14934/chikyukagaku.53.59

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DOI： 10.1038/s41598-019-40680-w

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Research

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1126/sciadv.aau0872

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DOI： 10.1016/j.chemgeo.2018.03.013

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DOI： 10.1016/j.chemgeo.2017.12.030

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41598-018-24205-5

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

The excess radiocarbon produced by nuclear bomb testing in the atmosphere in the 1950s-1960s (bomb-C-14) is used as a tracer in the surface ocean, extending our understanding of geophysics and biogeochemical cycles. However, there is no bomb-C-14 record for the high-latitude western North Pacific Ocean because of the paucity of long-lived marine calcifying organisms equivalent to reef-building corals. The shells of Stimpson's hard clam, Mercenaria stimpsoni, potentially provide such a record because the clam's lifespan is very long (>100 years). We analyzed C-14 in six live-caught M. stimpsoni shells from the western North Pacific (39.4 degrees N, 142 degrees E) and report, for the first time, the bomb-C-14 record with robust calendar ages based on annual growth increments. The value was constant in 1934-1952 (C-14=-66), with a sudden increase in 1959, a peak in 1974 (107), which was 60 lower than that of the Kuroshio Current, a gradual decline after 1974, and a current value of 16-18, which is approximate to 10 parts per thousand higher than the atmospheric value. The bomb-C-14 values are between the Kuroshio Current (the northwestern subtropical gyre) and Oyashio Current (the Western Subarctic Gyre) values, suggesting that the Tsugaru Current, downstream from the Kuroshio Current, mixes with the Oyashio Current after passing through Tsugaru Strait.

DOI： 10.1002/2017JC013678

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Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

<p>Many types of spherical carbonate concretions are common in sedimentary strata of various ages worldwide. However, the process by which these concretions form is not completely understood. This study investigated a gigantic spherical carbonate concretion, with a diameter of ~1.5 m, identified in Miocene fine tuffaceous sandstone in the Lower Toyohama Formation (Morozaki Group) on Chita Peninsula, Aichi prefecture, Japan. Detailed field and microscopic observations, porosity measurements, mineralogical examination, and geochemical analyses were carried out to understand the formation of such a large concretion in a marine sediment. The field exposure shows that the concretion formed during early diagenesis, before compaction due to subsequent sedimentation. Thin section observations and geochemical, isotopic, and XRD analyses revealed that the concretion formed as calcite and was later replaced by dolomite. By combining the porosity and dolomite composition with a porosity-burial depth relationship, it is estimated that the concretion formed at a depth below the seafloor of up to a few hundreds of meters, and was buried to about 2400 to 5500 m at the deepest. This depth is consistent with the depth of zeolite formation in the rock matrix, as estimated from the geothermal gradient. Interpretation of geochemical analyses suggests that the gigantic concretion was formed over several decades. Our results indicate that even gigantic carbonate concretions form quite rapidly after marine sediment deposition during early diagenesis.</p>

DOI： 10.5575/geosoc.2017.0039

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J-GLOBAL

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We are preparing a nationwide distribution map of strontium isotope ratio (Sr-87/Sr-86) in Japan, using stream sediment to obtain basic Sr-87/Sr-86 data for the provenance analysis of food production and archaeological substances. To clarify the effect of particle size on Sr-87/Sr-86 in stream sediments, we analyzed stream sediment from the Shigenobu River system in Matsuyama, Ehime Prefecture, Japan, where a variety of silicate-dominated lithologies, that is, several bedrocks of andesitic, granitic, and siliciclastic sedimentary rocks, are distributed. This paper reports elemental concentrations and Sr-87/Sr-86 in stream sediments for six particle-size fractions (1000-500, 500-300, 300-180, 180-125, 125-75, and &lt; 75 mu m). The results from stream sediments were compared with results from bedrock units and stream water over the catchment. The elemental concentrations in stream sediment tended to increase with decreasing particle size in all lithologies; however, Sr concentrations varied less than other elements across particle sizes. For most of the samples, Sr-87/Sr-86 varied by less than 0.001 among the six particle-size fractions, which was less than the variation among the different lithologies. Therefore, Sr-87/Sr-86 in the &lt; 180 mu m particle-size fraction, which is normally used in Japanese nationwide geochemical mapping, should be a reliable proxy for bedrock Sr-87/Sr-86. The Sr-87/Sr-86 values in water samples from the Shigenobu River system were lower and less variable than Sr-87/Sr-86 in the stream sediments, and they did not faithfully correspond to the watershed geology. The inconsistency may reflect selective dissolution of Sr from plagioclase. Interestingly, Sr-87/Sr-86 values of the exchangeable fraction of stream sediment in the &lt; 180 mu m fraction were strongly correlated with Sr-87/Sr-86 of stream water samples. Because Sr-87/Sr-86 in plant and animal bodies reflects that of their water sources, the exchangeable fraction of stream sediment may be a useful proxy for geochemical provenance in Japan instead of stream water. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apgeochem.2017.09.004

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>The strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) is often used to identify the origin of agricultural products and the movement of ancient people, and a nationwide ⁸⁷Sr/⁸⁶Sr distribution map would greatly assist such studies. The Geological Survey of Japan (GSJ), AIST has already created nationwide element distribution maps using the <180 μm fraction of stream sediments, but this grain size fraction may not necessarily be suitable for mapping the ⁸⁷Sr/⁸⁶Sr isotopic ratio. Therefore, this study investigated the effect of grain size on elemental concentrations and ⁸⁷Sr/⁸⁶Sr ratios in stream sediments and compared their values with those of the source rocks. The stream sediments studied were collected from the granitic drainage basin of the Yahagi and Yada rivers in Aichi Prefecture, central Japan. The elemental concentrations and ⁸⁷Sr/⁸⁶Sr ratios of five fractions in the size range 1000–75 μm from the stream sediments of the Yahagi River tributaries varied with the grain size, and the variations corresponded to the heterogeneity of the mineral compositions in each fraction. The difference in the elemental concentrations and ⁸⁷Sr/⁸⁶Sr ratios among the sampling points was smallest in the 300–75 μm fractions, which showed ⁸⁷Sr/⁸⁶Sr and ⁸⁷Rb/⁸⁶Sr values that were closest to those of the source rocks. The coarser (>300 μm) and the fine (<75 μm) fractions of the stream sediments showed systematically higher ⁸⁷Rb/⁸⁶Sr and lower ⁸⁷Sr/⁸⁶Sr ratios than the Rb-Sr mineral isochron for the source rock, and the result suggests that 1) these fractions are enriched in K- and Rb-rich minerals such as K-feldspar, biotite, and hornblende; and 2) Sr is lost relative to Rb because of weathering processes. Furthermore, temporal variations in ⁸⁷Sr/⁸⁶Sr of the <180 μm stream sediments collected at a fixed sampling site in the Yada River were 0.001, which is smaller than the variations associated with grain size seen in the ⁸⁷Sr/⁸⁶Sr values in the granitic study area. Consequently, we concluded that, in granite areas, the <180 μm fraction of the stream sediments can be used for ⁸⁷Sr/⁸⁶Sr mapping, implying that a nationwide ⁸⁷Sr/⁸⁶Sr map can be made using sediment samples with a grain size of less than 180 μm.</p>

DOI： 10.2343/geochemj.2.0478

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Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Tohoku Geographical Association  

<p>Maibah beach is located between Higashihenna promontory and Miyato-zaki （promontory）, southeast of Miyako Island. Along the sandy beach, beachrock develops intertidal zone. A large boulder lying on the eastern part of the beach has been recognized as a fossil <i>Tridacna gigas</i>. We collected two samples from the boulder in order to determine the age of its outer layer, and noticed that the cross section was different from <i>Tridacna gigas</i>. The samples indicated obviously a characteristic of coralline structure. Then identification and radiocarbon dating of the samples were performed.</p><p>The results show that coral is <i>Porites</i> sp. and probably <i>in situ</i>, and that it was transported from lagoon and beached on the shore, judged from the field observation. The calibrated ages were 1626 cal AD and 1679 cal AD, respectively. It is considered that <i>Porites</i> had transported and beached on the shore by huge tsunamis or high waves of typhoon. Unfortunately there was no huge typhoon record, and then we tried to correlate calibrated age of <i>Porites</i> with historical tsunami and earthquake records. According to historical record, Miyako Islands were attacked by strong earthquake of AD 1667 which probably caused tsunami. An average calibrated age of <i>Porites</i> （1653±23 cal AD） coincides with AD 1667 earthquake tsunami with a margin of statistical error. However, age of removed soft outer layers of <i>Porites</i> strongly suggests that it was transported from its original habitat to the present location not only by AD 1667 earthquake tsunami but also by AD 1771 Meiwa Tsunami.</p>

DOI： 10.5190/tga.69.3_119

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CiNii Research

Language：Japanese   Publisher：UNIV ARIZONA DEPT GEOSCIENCES  

Charcoal is widely used for radiocarbon dating in archaeological and paleoenvironmental studies. Reliable C-14 dating requires appropriate chemical treatment to remove postdeposition contamination from the charcoal samples. This study assesses two pretreatments: acid-base-acid (ABA) and acid-base-oxidation with stepped combustion (ABOx-SC). In addition to C-14, the effects of the treatments on the chemical structure and composition of charcoal were studied using Fourier transform infrared spectroscopy (FTIR) and C/H/O elemental analysis. Samples of pine wood charred in the laboratory at 270, 300, 400, 500, and 600 degrees C, and environmental samples of charred pine wood from pyroclastic flow deposits in southern Kyushu, Japan, were tested. The laboratory-charred samples showed that NaOH treatment removed highly hydrophilic organic components derived from endogenous and exogenous organic materials in the samples and that oxidation treatment caused the oxidative degradation of molecules in samples starting from its edges. The ABA-treated environmental charcoal yielded younger C-14 dates than the ABOx-treated samples, probably owing to the effects of remaining organic contaminants bound to the edges of the aromatic molecular structures produced by the original pyrolysis. Meanwhile, it was found that ABA-SC treatment can reduce contaminants as effectively as ABOx-SC treatment. This implies that the stepped combustion (SC), not the chemical oxidation, is the key to reduce contaminant residue left after ABA and ABOx treatments. The results in this study indicate that the investigation of the structural and compositional changes of charcoal during its pretreatment is useful for assessment of the reliability of the C-14 ages.

DOI： 10.1017/RDC.2016.29

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Geochemical Society of Japan  

Chemical compositions and Sr isotopic ratio (⁸⁷Sr/⁸⁶Sr) of stream sediments collected from Akiyoshi-dai, where is underlain by a large-scale limestone bedrock, were measured to investigate the influence of limestone bedrocks on geochemical maps. The sediments were sieved with eight screen sizes, and their bulk and acetic acid soluble fractions were both analyzed. 50–100% of the total Ca was extracted by acid leaching from stream sediments in the catchment of Akiyoshi limestone, indicating that Ca exists mainly in carbonate materials. In contrast, only 5–10% and 15–45% of the total Sr were extracted from their coarse (>125 μm) and fine particles (<125 μm),respectively. Therefore, Sr exists dominantly in aluminosilicate minerals even in stream sediments originated from limestone bedrock. Because the acid extraction percentages of Ca and Sr increase exponentially below 125 μm of grain size, carbonate materials would be supplied by fine-grained particles from limestone bedrock. ⁸⁷Sr/⁸⁶Sr ratios in the acid soluble fractions were systematically lower than those of the bulk fractions and comparable to ⁸⁷Sr/⁸⁶Sr of Akiyoshi limestone. Although limestone bedrock apparently scarcely influence on Sr concentration and ⁸⁷Sr/⁸⁶Sr of stream sediments, ⁸⁷Sr/⁸⁶Sr of carbonate materials is successfully extracted from the bulk sediments using acetic acid-based extraction method.

DOI： 10.14934/chikyukagaku.50.11

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Speleothem C-14 has recently emerged as a potentially powerful proxy for hydrology changes in comparison with atmospheric C-14 calibration curve, rather than as a direct dating tool, apart from a time marker using bomb peak of C-14. Some possible causes for the relationship between speleothem C-14 content (or dead carbon fraction: DCF) and karst hydrology have been proposed, such as changes in temperature, precipitation, drip water flow dynamics, cave air ventilation, soil air pCO(2). In this study, we investigated seasonal variation in C-14 and delta C-13 of drip water in Ryugashi Cave, Shizuoka Prefecture, central Japan, to examine the causes of the C-14 and delta C-13 variations in a speleothem. The results show that different C-14 concentrations and delta C-13 values of drip water from the Ryugashi Cave, were exhibited at different sites of the Caves No. 1, No. 3, and No. 4, which have different temperature, air pCO(2), and flow paths. Further, the C-14 and delta C-13 of drip waters showed seasonal variations at all sites, which were lower in fall and winter, and higher in spring and summer, though the extent of the variations was different among the sites. The C-14 in drip waters tended to be correlated with the drip rates: C-14 tended to be higher in drip waters with higher drip rates, and also correlated with rainfall amount around the Ryugashi Cave, especially for the drip waters in Cave No. 3, which are considered to have simpler flow paths. The increase in rainfall amount could bring the increase in drip rate of drip water, and then the decrease in interaction between solution and karst, resulting in C-14 increase (DCF decrease) in drip water. Accordingly, the reconstruction of precipitation could be performed using C-14 variation in a speleothem formed by drip water with simple flow dynamics. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2015.05.020

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Carbonate concretions occur in sedimentary rocks of widely varying geological ages throughout the world. Many of these concretions are isolated spheres, centered on fossils. The formation of such concretions has been variously explained by diffusion of inorganic carbon and organic matter in buried marine sediments. However, details of the syn-depositional chemical processes by which the isolated spherical shape developed and the associated carbon sources are little known. Here we present evidence that spherical carbonate concretions (diameters. : 14 similar to 37 mm) around tusk-shells (Fissidentalium spp.) were formed within weeks or months following death of the organism by the seepage of fatty acid from decaying soft body tissues. Characteristic concentrations of carbonate around the mouth of a tusk-shell reveal very rapid formation during the decay of organic matter from the tusk-shell. Available observations and geochemical evidence have enabled us to construct a 'Diffusion-growth rate cross-plot' that can be used to estimate the growth rate of all kinds of isolated spherical carbonate concretions identified in marine formations. Results shown here suggest that isolated spherical concretions that are not associated with fossils might also be formed from carbon sourced in the decaying soft body tissues of non-skeletal organisms with otherwise low preservation potential.

DOI： 10.1038/srep14123

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PubMed

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Research

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CiNii Research

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Radiocarbon  

To study the effect of ultrafiltration on the radiocarbon ages of relatively poorly preserved bones in Japan, we analyzed the 14C dates of high-molecular-weight (HMW) gelatin samples and compared them with those of other extracted organic fractions, unfiltered gelatin samples extracted from NaOH-treated or NaOH-untreated collagen, and XAD-purified hydrolysates of animal fossil bones (~4600 BP; gelatin yield of 2-4%) from the Awazu underwater archaeological site, Shiga, Japan. NaOH-treated, unfiltered gelatins and XAD-purified hydrolysates showed statistically similar 14C ages to those of HMW gelatins. The 14C ages of the HMW gelatins were the oldest and similar to those of wood collected from the same layer as the bones, and the NaOH-treated, unfiltered gelatins gave 14C ages within the acceptable margins of error; therefore, ultrafiltration was effective for accurate 14C dating, while NaOH-treated gelatin without ultrafiltration was also sufficient to obtain accurate 14C dates on the animal bones. The 14C ages of human skeletons (~750 BP; gelatin yield of 2-11%) from 5 individuals excavated from an archaeological site in Yuigahama, Kamakura, Japan, showed statistically the same 14C ages as NaOHtreated, unfiltered gelatins and HMW gelatins within the margins of error, although HMW gelatins were likely to give slightly older ages than unfiltered gelatin with a yield of less than ~3%. These results indicate that unfiltered gelatins extracted from fossil bones of gelatin yield more than ~3% can produce accurate 14C ages without the need for ultrafiltration. Ten bone fragments from 3 humans showed the same 14C ages for each individual, suggesting that any bone part from an individual can be used to obtain a representative age. The 14C ages of tooth enamels of 2 individuals were 35 and 70 yr older than their bone ages. Death dates obtained from these age gaps agreed with those determined by morphology. © 2013 by the Arizona Board of Regents on behalf of the University of Arizona.

DOI： 10.2458/azu_js_rc.55.16334

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Geochemical mapping of ⁸⁷Sr/⁸⁶Sr ratios in Shikoku Island and the Kii Peninsula of Southwest Japan was performed using 233 samples of stream sediments (<180 μm). The spatial distribution of ⁸⁷Sr/⁸⁶Sr ratios successively increases from northern to southern geological units, with a gap at the Median Tectonic Line (MTL). In the Inner Zone divided by the MTL, a zone with Cretaceous granitoid rocks of the Ryoke Belt and sedimentary rocks of the Izumi Group, the ⁸⁷Sr/⁸⁶Sr ratios are measured at ~0.710. In the Outer Zone, a zone with Cretaceous metamorphic rocks of the Sanbagawa Belt and Jurassic to Miocene accretionary complexes of the Chichibu Belt and Shimanto Belts, the ⁸⁷Sr/⁸⁶Sr ratios tend to fall in the range from 0.706 to 0.715, tend to increase from north to south, and are highest in the youngest accretionary complex of the Southern Shimanto Belt. The ⁸⁷Rb/⁸⁶Sr-⁸⁷Sr/⁸⁶Sr plots for stream sediments more clearly reveal the differences and similarities of their bedrocks, such as the different trends among the stream sediments of the Inner and Outer Zones. Samples collected from the Inner Zone show almost the same ⁸⁷Rb/⁸⁶Sr-⁸⁷Sr/⁸⁶Sr field as their source rocks, while most of the samples derived from accretionary complexes in the Outer Zone are plotted around a mixing line of older continental detritus and igneous-rock-derived materials. In light of the other geochemical characteristics observed, particularly the REE chemical features of the stream sediments and zircon ages in the basemental sedimentary rocks, the accretionary complexes in the Outer Zone may be mainly formed from the same source rocks, namely, igneous-rock-derived materials and continental detrital materials with different mixing ratios and a larger ratio of continental materials in the Southern Shimanto Belt. This study indicates that ⁸⁷Sr/⁸⁶Sr ratios of stream sediments strongly reflect the isotopic composition of the source rocks and are very useful for distinguishing the various geological and geochemical settings of the source rocks.

DOI： 10.2343/geochemj.2.0248

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Language：Japanese   Publisher：WILEY-BLACKWELL  

In granitic rocks, fracture networks typically provide pathways for groundwater flow and solute transport that need to be understood to assess the long-term performance of deep underground storage or disposal facilities such as radioactive waste repositories. However, relatively little is known about the long-term processes of fracturing and/or the longevity of flow paths (FP) in granitic rocks distributed within orogenic belts. To clarify these issues, Japanese plutons of different ages and in situ fractures in granite at the Mizunami Underground Research Laboratory (MIU) located in central Japan were studied. Detailed structural characterization and geochemical analysis of in situ fracture fillings sampled from a depth of 300m were carried out to clarify the relationship between fracturing and mineral infilling processes. Different plutons show identical episodes of fracturing and fracture filling, consisting of: brittle tensile fracturing, due to decreasing temperature through the ductilebrittle transition after plutonic intrusion (Stage I); relatively rapid uplifting (ca. a few mm/year) accompanied by hydrothermal water circulation, which produced uncrushed layered mineral fillings (Stage II); and a period of low-temperature meteoric water circulation following exposure after uplift (Stage III). The parageneses of carbonate mineral fracture fillings and their carbon isotopic compositions (14C, 13C) show that there were distinct episodes of carbonate mineral precipitation during the rapid uplifting of a pluton. The carbonate minerals that formed during each episode incorporated carbon from a distinct source. The evolution of fillings identified here enables development of a specific model of fracturing and persistence of fluid-conducting systems in the plutons of the orogenic field.

DOI： 10.1111/gfl.12008

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

As part of the ongoing development at the AMS facility of the Center for Chronological Research at Nagoya University to radiocarbon (C-14) analyze samples smaller than 0.5 mg carbon (mgC), a compact graphitization manifold has been built. Tests with various reference materials show it performs well for samples as small as 0.1 mgC. Preparation with this new system is compared with the performance of the older protocol for regular-sized samples. Furthermore, it is shown that the addition of Cu and Ag before and stepwise heating during sealed-tube combustion of samples with high S content improve the degree of conversion to CO2 without having to resort to special purification measures such as the use of Co3O4 + Ag reagent and an n-pentane/LN2 trap before graphitization. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2012.02.036

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Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

Using data from previous studies and newly collected data, we compared the measured radiocarbon ages of molluscan shells, common reed (Phragmites australis) and pine needles (Pinus thunbergii) collected in 1966, 1970, 1990 and 2008 at Lake Biwa in Japan, and of archaeological samples, to examine radiocarbon reservoir effects at Lake Biwa. We also tested for differences in the radiocarbon reservoir effect between species and locations in the lake. The effects of nuclear bomb tests conducted in the 1950s and 1960s are clear, the offset between atmospheric C-14 and the Lake Biwa freshwater C-14 is larger for this period because the atmospheric C-14 is so high. The semiclosed Lake Biwa system is in dynamic equilibrium with the atmosphere, resulting in the C-14 content of the water following the changes in atmospheric C-14 caused by nuclear testing. The shells collected after 1990 had radiocarbon ages that were 330-450 C-14 years older than those of the coeval atmosphere. The apparent differences in radiocarbon age (about 300 C-14 years) between shell fossils and wood samples excavated from the same layer of the submerged Awazu shell midden at Lake Biwa suggest that the radiocarbon reservoir effect also existed in the middle Holocene (the Middle Jomon period, about 5000 years ago). Because the present-day average residence time of Lake Biwa water is 3-6 years, its direct influence on the radiocarbon reservoir effect is small, which suggests that old carbon has been supplied into Lake Biwa. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2012.09.027

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Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

Ultrafiltration can effectively remove low-molecular-weight (LMW) contaminants from bone gelatin to extract high-molecular-weight (HMW) proteins that are derived from original bone collagen, though it cannot remove HMW collagen crosslinked with humic acids. Therefore, ultrafiltration is often used to obtain more accurate C-14 dates of bones. However, ultrafiltration may introduce new contaminants to bone gelatins, mainly from ultrafilters used. To study the effects of ultrafiltration on C-14 age, we analyzed the C/N ratio, delta C-13(PDB) and delta N-15(AIR) values, and C-14 ages of acid-soluble bone collagen obtained by decalcification, gelatin extracted from acid-insoluble bone collagen, and the HMW gelatin and LMW fractions produced during ultrafiltration of the extracted gelatin. Bone samples from the Fifth International Radiocarbon Intercomparison (VIRI) were used: VIRI-E (mammoth), -F (horse), -G (human), and -I (whale).
In this study, carbon and nitrogen content and gelatin yields were used to evaluate collagen preservation in the VIRI bone samples. Radiocarbon ages, delta C-13(PDB) and delta N-15(AIR) values of unfiltered and HMW gelatins were obtained and compared with the published consensus values. The LMW fraction was found to exhibit different values from those of the other fractions, indicating the possible presence of extraneous contamination. The Vivaspin (TM) 6 ultrafilters used in this study were analyzed and radiocarbon dated both before and after cleaning. We present evidence to suggest that LMW fraction contaminants could be derived from the ultrafilters rather than humic substances. Excessively long ultrafiltration time was suspected to have contaminated the bone samples with material from the ultrafilter, because those samples exhibited older C-14 ages than did those filtered for shorter durations. The results in this study indicate that C-14 ages of unfiltered gelatin extracted from well-preserved bones can be sufficiently accurate, and that care should be taken not to contaminate bone gelatin during ultrafiltration. Additional studies investigating bones with different degrees of degradation are needed to determine the effectiveness of ultrafiltration for accurate C-14 dating when the collagen is not so well preserved. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2012.06.016

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publisher：Radiocarbon  

We investigated the radiocarbon ages and carbon and nitrogen isotope ratios of human skeletal remains from burials at the Yuigahama-minami and Chusei-Shudan-Bochi sites in the Yuigahama area (Kamakura, Japan), which we believe are associated with the great attack on Kamakura by Nitta Yoshisada in AD 1333. The human bones produced enriched δ13C and δ15N values that could be affected by consumption of protein from marine fish and/or mammals with high δ13C and δ15N, and therefore older apparent 14C ages. We thus estimated the marine reservoir effect on human skeletons to determine their true ages. The IsoSource isotope mixing model was employed for reconstructing percentages of marine protein in the human diet, and calibrated calendar dates for the 14C ages were calculated using the marine percentages. At the Yuigahama-minami site, most skeletons from individual burials now date to the last phase of the Kamakura period or the early part of the Muromachi period, while skeletons from mixed human-animal multiple burials date to the latter part of the Kamakura period. The humans from the individual burials, consisting of normal ratios of adult males, could have died a natural death, though the site could also have been used to inter victims of the battle of 1333. The humans from mixed human-animal burials, consisting of a high proportion of infants, were not victims of the 1333 battle, but the site may have been used to inter victims of the Kamakura earthquake in 1293, which resulted in a catastrophic tsunami. On the other hand, the skeletons from multiple burials in the Chusei-Shudan-Bochi site all date to the middle Kamakura period. Coupled with the fact that most humans in the site are male but show no evidence of injuries by sword cuts, it is likely that burials of the Chusei-Shudan-Bochi site could have been a collective interment following the Jinji earthquake in 1241, the Shoka earthquake in 1257, or the Shoka famine in 1258 in the middle Kamakura period. The results of this study indicate that humans from burials in the Yuigahama region were not necessarily victims of the attack by Nitta Yoshisada on Kamakura, but instead were likely victims of natural disasters such as large earthquakes and severe famines, which often occurred in the middle Kamakura period. © 2012 by the Arizona Board of Regents on behalf of the University of Arizona.

DOI： 10.1017/s0033822200047287

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：Japan Cement Association  

Radiocarbon method has been applied to concrete in order to estimate progression and age of carbonation in concrete. Concrete cores from a building constructed in 1967 on the campus of Nagoya University, Japan, were collected in 2008, and were investigated for ¹⁴C, δ¹³C, and carbon content. The amount of carbon dioxide was 8％ at the concrete surface where the concrete is highly carbonated, decreasing with depth, and was 1％ at the depth where carbonation is hardly observed. The measured ¹⁴C values were 144 to 148pMC at the carbonated surface and 71 to 82pMC at the depth of less carbonation, decreasing from the surface down to the depth. These profiles can be interpreted as the following：（1）The age of carbonation in the concrete can be estimated by the variation of ¹⁴C and carbon concentrations, coupled with atmospheric ¹⁴C value at 1967（~170pMC：Hua and Barbetti, 2004）and the present one（~100pMC）. Most part of CO₂ in the surface concrete is estimated to be absorbed and fixed in ten years after construction.（2）The deeper part of the concrete also contains small amount of atmospheric CO₂, which is 43 to 78％ of CO₂ in the deeper part. However, δ¹³CPDB value in the deeper part is -25 to -21‰, and is significantly lower than those of atmospheric CO₂（δ¹³C≅8‰）and marine sedimentary limestones with geological ages（δ¹³C≅0‰）. Carbon isotope compositions, ¹⁴C and δ¹³C, in the deeper part of concrete cannot be explained by a simple mixing of the two components. There are two possible causes of the lowest δ¹³C value：material originating from cements and/or concrete, and direct absorption of atmospheric CO₂ by high-pH cement solutions with kinetic effects in the high-pH zone.

DOI： 10.14250/cement.64.139

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DOI： doi:10.1016/j.nimb.2009.10.063

CiNii Research

Language：Japanese   Publisher：TAYLOR & FRANCIS LTD  

We have considered the applicability of strontium isotope analysis, using Laser Ablation-assisted Resonance Ionization Mass Spectrometry (LA-RIMS), to the determination of bone origin. We separated the uncertainty into two categories: ion counting statistics, and short-term or uncontrollable shifts of experimental conditions; only the former decreases with increasing signal intensity. Additionally, we confirmed that long-term shifts of isotope ratio in LA-RIMS can be cancelled by an internal correction method. We preliminarily estimated the precision of our technique to be 0.7% (1 sigma) for 10(5) laser shots: the accuracy is also confirmed within the present uncertainty through the comparison with a reference value.

DOI： 10.1080/00223131.2008.10875986

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CiNii Research

CiNii Research

Language：Japanese   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Since 1994 a geochemical mapping project has been undertaken in Aichi prefecture, central Japan, with the aim of establishing a database to contribute to environmental assessment in the region. To date more than 1200 stream sediments have been collected and analyzed. The samples were analyzed for 10 major elements by X-ray fluorescence spectrometry and loss-on-ignition.
The analyses show that stream sediments from areas with sedimentary bedrock are enriched in SiO2 and mafic elements such as TiO2 and Fe2O3 compared to areas with granitic bedrock. The SiO2 enrichment is mainly due to the amount of quartz and the enrichment in mafic elements is due to biotite, both of which are derived from the sedimentary bedrock. In contrast, sediments derived from granitic bedrock are characterized by high abundances of elements contained in feldspars such as Na2O and CaO. This contrast in elemental distribution (e.g., Na2O/TiO2 ratio) can be useful for geological mapping in the areas covered by vegetation and with poor bedrock exposure. The relative abundances of Ca, Na and K in the stream sediments suggest that the Inagawa granite, one of the main granite bodies in the study area, can be classified into four distinct types. This classification is distinct from previous classifications based on geological and petrochemical studies. It is confirmed that analysis of geochemical compositions of stream sediments has considerable potential as a tool in geological studies including lithological mapping. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apgeochem.2006.09.011

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Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：Tree-Ring Research  

14C wiggle-matching was applied to two wood samples closely related to geological and archaeological events with associated dendrochronological dates, to demonstrate the accuracy of 14C dating with accelerator mass spectrometry (AMS). Wiggle-matching on charred wood with bark, excavated from a pyroclastic mud-flow deposited by the huge 10th Century eruption of the Baitoushan Volcano, revealed the eruption age as cal A.D. 935 +8/-5 with 95% confidence. This date is consistent with the eruption age of A.D. 912 to A.D. 972 estimated by dendrochronology on two wooden boards that had clear stratigraphical connections to the B-Tm tephra deposit in Japan, an ash fall layer formed by the eruption of the Baitoushan Volcano. The date is also consistent with an A.D. 937-938 date estimated by the analysis of varved sediments from Lake Ogawarako in Aomori prefecture. The other wooden board collected from the Mawaki archaeological site in Ishikawa prefecture was wiggle-matched as 783 +13/-11 cal B.C. with 95% confidence, which is consistent with the dates of 830 cal B.C. to 759 cal B.C. obtained for seven wooden poles from the same wooden structures as the wooden board. These results are highly encouraging for obtaining accurate dates on wood when dendrochronology cannot be used. Copyright © 2007 by the Tree-Ring Society.

DOI： 10.3959/1536-1098-63.1.37

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CiNii Research

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Language：Japanese   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Geochemical maps expressing areal distributions of chemical elements in the earth's land surface have been published in several countries in relation to various global environment issues. The authors have applied a radiogenic isotope ratio, Sr-87/Sr-86, to geochemical mapping in order to understand the geological origin, transportation and dispersion system of chemical elements in the earth's land surface. The Sr isotope ratio is a useful tracer for distinguishing the geological origin of surficial deposits, especially in areas where surface exposure of bedrocks is low, because it is not significantly altered by the processes of weathering and transportation. Most bedrocks in the Japanese islands are covered by plants, soils and urban areas. In this study, 142 of 1219 stream sediments (&lt; 180 mu m) collected from the northeastern part of Aichi Prefecture, in the central part of Japan (75 km x 30 km), were analyzed. Their Sr isotope ratios range from 0.7086 to 0.7315 with an average of 0.7129, except for one sample. This average is higher than the mean of the upper crust of the Japan Arc (the Japanese Island Crustal Composite, JICC), 0.7077. This difference can be attributed to the below-average presence of young volcanic rocks, generally having lower Sr-87/Sr-86 values, and the above-average presence of granitic rocks, in the study area compared with the surface exposure of the Japan Arc. The first factor controlling the distribution of Sr isotope ratios is the bedrock distributed around the sampling points. Regional variation in the Sr-87/Sr-86 value shows that it is higher in the western and southeastern parts, where sedimentary rocks and metamorphic rocks are distributed, and that it is lower mainly in the central part, where granitic rocks are distributed. The Rb-87/Sr-86-Sr-87/Sr-86 plot for stream sediments more clearly reveals the differences and similarities of bedrocks. In some locations, the distribution of Sr isotope ratios does not correspond to that of bedrocks on the geological map. One reason is the existence of unmapped bedrock, for example, small intrusive masses of granite. The other is fluvial transportation and dispersion. The distribution of the isotope ratios suggests that some stream sediments include surficial deposits from a few km upstream. Application of the Sr isotope ratio to geochemical mapping is useful for revealing both the distribution of unexposed bedrocks and the transportation of surficial deposits. Information on unexposed bedrocks will be expected to contribute to the improvement of geological mapping. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apgeochem.2005.12.003

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Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

In measuring radiocarbon ages of fossil bone samples, it is necessary to extract pure bone protein from the samples by chemical treatment. To evaluate the effect of the chemical treatment including XAD-2 chromatography on carbon and nitrogen isotopic values, we measured C/N ratio, delta(13)C and delta(15)N in decalcified fraction, gelatin, hydrolysate, and XAD-treated hydrolysate extracted from fossil bones together with modem samples. The C/N ratios of the collagen fractions progressively decreased as chemical treatment proceeded. The delta(13)C values of the fractions became more positive as purification proceeded. There was an overall +0.5 similar to+2.0 parts per thousand difference in delta(13)C and a slight trend of decrease in delta(15)N during chemical processing and around +0.3 parts per thousand difference in delta(13)C and +0.2 parts per thousand in delta(15)N during XAD-2 treatment only. The large change in C/N ratio and delta(13)C of the hydrolysates following XAD-2 chromatography in the Bovine Achilles tendon collagen standard could be explained by the removal of lipids unextracted before the XAD-2 treatment. There was no difference in 613 C between hydrolysates and XAD-treated hydrolysates in fossil bones because the latter contains negligible preserved lipids. Fossil bones and lipid-extracted collagen standard showed the similar C/N change and isotopic fractionation during sequential chemical treatment. Individual amino acid standards showed little to no increase in delta(13)C and delta(15)N values during XAD-2 treatment, except for aspartic acid and glutamic acid, which showed pronounced increase in delta(15)N values. Furthermore, regarding amino acid compositions separated by XAD-2 treatment, alanine and glycine tend to be enriched, while valine, threonine, isoleucine, leucine, and serine compositions tend to be depleted. The carbon and nitrogen isotopic fractionation during sequential chemical treatment might reflect variation in the amino acid composition of the extracted fractions due to degradation, such as decarboxylation, rather than removal of contaminants. The variation during XAD-2 treatment is due to both degradation by HCl and isotopic fractionation related to the XAD-2 resin. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chemgeo.2005.06.005

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CiNii Research

Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

We examined different concentrations of HCI, such as 0.4, 0.6, 0.8, 1.0 and 1.2 M, for decalcification of fossil bones and different times of 0.1 M NaOH treatment on collagens to determine the best conditions for purifying collagen through extraction of humic contaminants, and compared the alkali treatment method with the XAD-2 treatment method for several types of fossils. The yield of acid-insoluble bone fractions did not change over the range from 0.4 to 1.0 M HCI and decreased suddenly with 1.2 M HCl on decalcification, and the 14 C ages of the extracted gelatins from the five decalcified fractions were unchanged, suggesting that &lt;1.0 M, and probably about 0.4 M, is recommended to the best concentration of HCI to decalcify fossil bones efficiently. The alkali treatment was done with 0.1 M NaOH at room temperature. The NaOH-treated collagens, with a considerable loss of organic bone protein especially for long treatment time, gave almost the same C-14 ages as those of the XAD-purified hydrolysates. The NaOH-treatment time should be less than several hours to avoid a loss of collagen. The fossil bones used are relatively well-preserved, but the alkali treatment could bring about a lot of loss of organic bone proteins for poorly-preserved bones. The XAD-2 treatment method is effective for accurate radiocarbon dating of fossil bones, if the XAD-2 resin is completely precleaned. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2004.04.060

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Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

In 1996/1997, a C-14-AMS system (model 4130-AMS) manufactured by High Voltage Engineering Europe (HVEE), B.V., The Netherlands, was installed at the Center for Chronological Research (CCR), Nagoya University. The system provides highly precise and accurate C-14 determinations as well as delta(13)C values for graphite targets (1.5 mg carbon and 3 mg iron powder) prepared from standards and samples. One sigma errors in C-14 ages typically range from +/-20 to +/-40 yr for materials younger than 8000 BP, depending on absolute C-14 ages or C-14 counting uncertainties. Standard deviations of C-13/C-12 ratios range from +/-0.1parts per thousand to +/-0.9parts per thousand. For relatively young samples, accuracies of less than 10parts per thousand are obtained using IAEA reference materials and FIRI test samples. Background levels on the C-14-AMS system range from 52 to 54 ka BP for a pure graphite powder. The HVEE C-14-AMS system at the CCR has been used routinely to date samples with a variety of research applications. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2004.04.027

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

CiNii Research

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Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

CiNii Research

CiNii Research

CiNii Research

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  

The XAD-2 chromatography method was examined for its ability to efficiently eliminate exogenous organic matter from fossil bones and to improve the accuracy of radiocarbon (14C) dating and stable isotope determinations on bone proteins. The fossil bones used in the experiment were animal fossil bones collected from the Awazu submarine archaeological site, Shiga, Japan. For comparison, the gelatin-extraction method was also applied to the same samples. It was found that the gelatin-extraction method is sufficient for 14C dating on well-preserved bones, but insufficient on poorly preserved bones, containing less than 1% extractable gelatin. The XAD-2 resin is useful for the clean up of proteins especially from poorly preserved bones. The carbon stable isotope fractionation of around 1‰ by XAD-2 treatment on modern collagen standards was larger than reported previously. The isotopic variation by sequential extraction of bones probably originates from changes in the amino acid composition and seems to be less sensitive to the indication of the removal of organic contamination. © 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(00)00397-9

Scopus

Language：Japanese   Publisher：Japan Association for Quaternary Research  

Accurate radiocarbon (¹⁴C) and carbon isotope measurements of fossil bones require complete removal of all exogenous carbon. XAD-2 chromatography was used to eliminate the foreign organic matter from bones. The fossil bones used in the experiment were animal bone fragments collected at the Awazu submarine archeological site. The bone samples were demineralized with 0.8M HCl at 4°C, and the acid-insoluble residue was concentrated by centrifugation and lyophilized. The demineralized bone powder was hydrolysed with 6M HCl at 110°C. Solid components were removed by centrifugation before the filtered hydrolysate was passed through the XAD-2 resin used for removal of fulvic acids. In addition, the gelatin extraction method of decalcification in a cellulose tube with 1.2M HCl, followed by heating at 90°C in water was used for the same species to compare the ability of the two methods to remove organic contaminants.<br>The purified hydrolysates obtained from XAD-2 chromatography have more positive δ¹³C values and older ¹⁴C ages than gelatin collagens extracted from hot water. The difference tends to become greater for poorly preserved fossil bones containing less than 0.7% collageneous materials. The fulvic phases give apparently younger ages and significantly more negative δ¹³C values than bone organic carbon. Furthermore, the XAD-treated hydrolysates of gelatin collagens give the same ¹⁴C ages (older than those of gelatin collagens) as the XAD-purified hydrolysates. The result indicates that the gelatin extraction method is sufficient for ¹⁴C dating on well-preserved bones, but insufficient on poorly preserved bones, because hot-water extraction does not totally remove exogenous organic carbon. Therefore, XAD-2 resin is recommended for accurate ¹⁴C and carbon isotope measurements.

DOI： 10.4116/jaqua.39.547

CiNii Research

Language：Japanese   Publisher：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  

In 1996/97, we installed a second-generation AMS system (model 4130-AMS) manufactured by HVEE, B.V., The Netherlands. Although we encountered a lot of problems during the installation and tuning up of the machine, our new system has now reached good stability and reproducibility in performing 14C/12C and 13C/12C measurements. According to the reproducibility tests conducted in January 1999, where six graphite targets prepared from HOxII standard material were measured, the standard deviation for 14C/12C reproducibility is around 1.6%e (comparable with counting statistics) and that for 13C/12C is 0.28%e. The background level of the AMS system was measured using a pure graphite (commercial graphite rod). It lies between 50 and 55 ka BP. We are still on the way to reduce the background. However, we are now prepared to start routine measurements of unknown-age samples. © 2000 Elsevier Science B. V. All rights reserved.

DOI： 10.1016/S0168-583X(00)00398-0

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publisher：Nagoya University  

XAD-2 resin is considered the good materials to separate quantitatively the polar amino acids from the less polar fulvic and humic acids. To evaluate if XAD-2 treatment affects isotope values, δ ^<13>C and δ ^<15>N were measured on bulk sample by a simple preparation, gelatin-collagen extracted by usual method, decalcified bone powder and XAD-purified hydrolysates from a modern well-preserved ivory sample "IVRY-1". Among three fractions of bulk, gelatin-collagen and decalcified ivory powder, there are almost no difference in both δ ^<13>C and δ ^<15>N. On the other hand, XAD-treated hydrolysate has apparently more positive δ ^<13>C and δ ^<15>N values than the three fractions. However, it is doubt whether the result is due to isotope fractionation by XAD-2 treatment because the fulvic and humic contamination in the collagen might affect isotope values of bulk, gelatin-collagen and decalcified ivory powder. The C/N ratio in fulvic and humic phases is significantly more higher than collagen. In the next study, we have to study modern collagen standards or amino acid standards to evaluate if XAD-2 resin introduce isotope fractionation.

CiNii Research

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese   Publisher：General Pharmacology  

1. Dietary docosahexaenoic acid (DHA) suppressed the age dependent increase in systolic blood pressure and prolonged the average survival time of stroke-prone spontaneously hypertensive rats (SHRSP). 2. Dietary DHA (1% and 5% in diets) altered the circadian rhythm of SHRSP, causing significant increases in ambulatory activity during the dark period. At the onset of stroke, desynchronization with light and dark phases and new biological rhythms were noted in all of the control SHRSP (DHA 0%). DHA treated SHRSP did not show such behavioral changes. 3. These effects were accompanied by the increase of DHA and the decrease of AA levels in plasma and brain cortex. 4. It was concluded that dietary DHA suppresses the development of hypertension and stroke-related behavioral changes, resulting in prolongation of the SHRSP's life span.

DOI： 10.1016/S0306-3623(96)00487-9

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English  

DOI： 10.18999/joueps.43.27

Other Link： http://orcid.org/0000-0002-0770-3273

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Isotopic data of Sm-Nd, La-Ce and Rb-Sr systems, rare earth element (REE) abundances and major element compositions are reported for the Archean Marble Bar Chert from the Towers Formation of the Salgash Subgroup, Warrawoona Group, Pilbara Block, Western Australia. The Marble Bar Chert records two Sm-Nd ages; 3.2±0.3 Ga for red (or black) and white banded cherts and 2.5±0.2 Ga for yellowish gray cherts. These ages contain relatively large uncertainties and are younger than 3.45 Ga U-Pb zircon ages previously reported for the Salgash Subgroup. The results imply some later perturbation in Sm-Nd system of these cherts after their formation. However, the older age of 3.2±0.3 Ga is close to the U-Pb zircon ages for the Salgash Subgroup within analytical errors and therefore can be regarded as the formation time of the banded cherts. On the other hand, the younger age of 2.5±0.2 Ga for the yellowish gray cherts is thought to reflect the time of later thermal events and the cherts do not retain their original chemical features. The 3.2 Ga Sm-Nd age for the Marble Bar banded cherts is the first Archean record obtained for the Archean cherts; their initial ε_Nd value of +1.0±3.0 holds the original nature at their formation without severe geochemical disturbance. The obtained mantle-like depleted or chondritic feature at 3.2 Ga for the banded cherts, together with their SiO₂ and Fe₂O₃∗ data and positive Eu anomalies in REE patterns, suggests substantially large contribution of hydrothermal solution derived from depleted- or chondritic-mantle to the cherts and inorganic origin of the cherts, which contrasts to Phanerozoic biogenic cherts.

DOI： 10.2343/geochemj.29.347

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CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Mass Spectrometry Society of Japan  

DOI： 10.5702/massspec.s24-02

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Mass Spectrometry Society of Japan  

DOI： 10.5702/massspec.s23-05

CiNii Research

Language：Japanese   Publisher：The Mass Spectrometry Society of Japan  

DOI： 10.5702/massspec.s22-19

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.69.0_157

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>A large number of carbonate concretion samples were collected during the dredging around Nagoya Port. Most of the concretion samples had biological remains such as crab, sea urchin, and bivalve as their nuclei. In this study, radiocarbon (14C) ages of the shells of the biological remains inside the concretions, as well as of the concretions, were determined. Based on the metabolic carbon ratios in the bivalvia and sea urchin shells calculated from the δ13C values, the 14C age of the shells was estimated to be 7,350−7,050 cal BP. The 14C dates of the carbonate concretions were older than those of the shells due to the metabolic carbon with older ages into the concretion carbon. The corrected age after removal of the old carbon was estimated to be 7,530−7,270 cal BP. The almost the same corrected ages between the shells and the concretions indicate that the carbonate concretions in the Nagoya Port area were formed by rapid concretion after the death of the organisms, which is consistent with the morphological findings of rapid concretion in the sediment. </p>

DOI： 10.14862/geochemproc.69.0_41

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>Iran Plateau has been considered as a part of the Alpine-Himalayan orogenic belts and is situated between two major sutures, Paleotethys suture in the north and Neotethys suture in the south. Most of the magmatic activities in Iran have been controlled by these two-ocean birth to death. The rupture-drift of the Iran microcontinent from the Arabian plate in the northern Gondwana and the rejoining in the Cenozoic can be considered as a typical Wilson cycle.</p>

DOI： 10.14862/geochemproc.69.0_116

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>Elucidation of the sources of carbon components (organic carbon, elemental carbon, carbonate carbon, etc.) in atmospheric aerosols is important to control air pollution and to a better understanding of global climate change. Air pollution in Iran, especially in urban areas, is increasing, but there has been little analysis of the carbon components in aerosols. The atmospheric aerosol in semi-arid Iran contains not only carbon particles but also a large amount of dusty aerosols such as soil particles, and it is important to understand not only the carbon component but also the inorganic elemental components in order to analyze the source of aerosols in this region. The purpose of this study was to determine the source of urban atmospheric aerosols in the region by analyzing ¹⁴C, δ¹³C, and inorganic element concentrations in urban atmospheric aerosols in the Kurdistan Province of Iran, near the border with Iraq. The results showed that the contribution of FC was larger in the winter season than in other periods, while the contribution of non-FC was larger from March onward. In addition, an increase in soil particles from Iraq and other western regions was observed during the spring season.</p>

DOI： 10.14862/geochemproc.69.0_141

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>Strontium isotopic ratios (87Sr/86Sr) of large volcanic blocks in the Maebashi mudflow deposit, which constitutes the basement of the Maebashi-Takasaki area in Gunma Prefecture, and the Tsukahara mudflow deposit, which constitutes the basement of the Saku-Karuizawa area in Nagano Prefecture, indicate that these mudflow deposits were brought by a failure event of Kurofu volcano, an initial stage volcanic edifice of Asama volcano. Furthermore, 14C ages of wood fragments buried in the deposits indicate that the mudflows were generated by the a failure event of Kurofu volcano during the last glacial period ca.27 ka cal BP (Sato et al., 2017, 2019, 2020, 2021, 2022) In this presentation, we present these results.</p>

DOI： 10.14862/geochemproc.69.0_200

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.68.0_206

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.68.0_153

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.68.0_28

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.68.0_66

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.68.0_125

CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2021.0_009

CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2021.0_003

CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2021.0_007

CiNii Research

Authorship：Lead author   Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.67.0_193

CiNii Research

Authorship：Last author   Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.67.0_157

CiNii Research

Authorship：Last author   Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.67.0_198

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.67.0_126

CiNii Research

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p>Travertine is calcium carbonate precipitated from groundwater and spring water, and is widely distributed in northwest Iran. It is one of the suitable samples which can reconstruct paleoenvironment on land with a high resolution.In this study, I first determine the formation age of the travertine and then reveal its source by a series of data of 14C, δ13C, δ18O, 87Sr/86Sr and major- and trace-elemental compositions.</p>

DOI： 10.14862/geochemproc.67.0_200

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.67.0_166

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CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2019.0_566

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.66.0_87

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.66.0_99

CiNii Research

Language：Japanese   Publisher：名古屋大学宇宙地球環境研究所  

Burned bones may not provide accurate 14C dating because of no remain of collagen, an organic fraction in bone, suffered from heating. It is a very crucial assignment to enable burned bone to be 14C-dated. The purpose of this study is to test the reliability of 14C dating of carbonate hydroxyapatite (CHa), an inorganic fraction in bone, by using some burned bones from archaeological sites. The samples tested are five burned bones with gray to black colors of known-age collected from the Göytepe and Damjili Cave archeological sites in Azerbaijan. The XRD patterns of the bones showed that they had not suffered from the heat of &gt;600ºC, and that they have low crystallinity of apatite. The 14C dates of the Göytepe and Damjili Cave bones were younger than the dates obtained by charred materials excavated from the same layer for 400 years and 1000–1700 years, respectively. The results indicate that the bones burned at the low temperature (&lt;600ºC) have been heavily contaminated through diagenetic alteration during burial because of low crystallinity of apatite, and that the contaminants can not be removed from bone CHa by chemical treatment used in this study. In conclusion, secondary carbonate can be removed from even bones burned at low temperature (&lt;600ºC) by acetic acid treatment, while exogenous carbon included into the inner site of CHa can not be removed. The degree of contamination from foreign carbon in bone samples varies with burial condition. Therefore, it is important to check the apatite crystallinity of bone and burial environment of bones to perform reliable 14C dating using bone CHa.遺跡に埋没している被熱骨に対し，炭酸ヒドロキシアパタイトを用いて信頼性のある14C年代測定が可能であるかを検証した．用いた試料は，アゼルバイジャンのギョイテペ遺跡とダムジリ洞窟遺跡から出土した被熱動物骨7点である．これらの骨試料の炭酸ヒドロキシアパタイトの14C年代は，同層から得られた炭化植物片の年代よりも，ギョイテペ遺跡においては400年，ダムジリ洞窟遺跡においては1000-1700年程度若くなった.XRDパターン結果から，二次的に付着した炭酸塩は，試料の酢酸処理によって除去されていると考えられ，若くなった原因は，炭酸ヒドロキシアパタイト結晶内に入り込んだ汚染炭素によるものと考えられる．ギョイテペ遺跡とダムジリ洞窟遺跡遺跡による年代差は，ギョイテペ遺跡の周辺は火成岩が，ダムジリ洞窟の周辺は石灰岩が分布していて土壌環境が異なっていたためと考えられる．今後さらに，埋没環境，被熱温度が異なる骨試料に対し，炭酸ヒドロキシアパタイトを用いて信頼性のある14C年代を得るための検討を行なっていく必要がある．

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.65.0_231

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.65.0_228

CiNii Research

CiNii Research

Authorship：Lead author   Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.65.0_291

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.64.0_14

CiNii Research

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.64.0_202

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.64.0_124

CiNii Research

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2017.0_443

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.63.0_182

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.63.0_73

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

<p></p>

DOI： 10.14862/geochemproc.63.0_22

CiNii Research

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.62.0_293

CiNii Research

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publisher：Japan Association of Mineralogical Sciences  

In the present study, whole-rock analyses, and Sr and Nd isotope analyses for granitoids (Ningyo Toge Granite, Tottori Granite, and Sangenya Granodiorite) from eastern Inbi Intrusives were carried out in order to discuss the plutonic magma history of the San-in Belt, Inner Zone of Southwest Japan. Whole-rock chemical characteristics categorize these granitoids as I-type. Rb-Sr isochron age for six samples of Ningyo Toge granites is given as 66.1 +/- 5.0 Ma (1 sigma). Relationship of epsilon NdI vs. epsilon SrI suggests that the parental magma of the Ningyo Toge Granite is probably not linked to that of the Tottori Granite.

DOI： 10.14824/jakoka.2014.0_181

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_120

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_245

CiNii Research

Authorship：Lead author   Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_121

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_347

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_134

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_244

CiNii Research

Language：Japanese   Publisher：名古屋大学年代測定資料研究センター  

An AMS system (Model 4130-AMS) dedicated to14C measurements, built by High Voltage Engineering Europe (HVEE), B.V., The Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests of its performance on carbon isotope measurements were completed in January of 1999, and routine measurements began in mid-2000. Since completion of the acceptance tests in early 1999, we have encountered a lot of troubles with the machine, particularly in 2002. Since the end of 2002, the machine has worked relatively well, expect for minor problems. The standard deviation (one sigma) of the 14C/12C ratio is around ±0.3% to ±0.4% (a bit larger than the uncertainty of about ±0.3% calculated from 14C counting statistics) and that of the corresponding 13C/12C ratio is ±0.03% to ±0.07% ， as are tested for HOxII targets. The number of targets measured was 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634 in each year from 1999 to 2012, respectively, and total number of targets measured by the end of 2012 is 19,674. The Tandetron AMS system worked well in the early half of 2012, with only minor failures. In September, a noise became large from the 12C-beam chopper, in the recombinator system, owing to the problem of a ferro-fluid-feedthrough, which had been used since June, 2008. We have replaced the ferro-fluid feedthrough to a new one. Soon after the chopper problem, the turbo molecular pump (TMP) in the recombinator system was damaged with the bearing of the rotating fan. We sent the pump to the supplier for repair. Because of the broken bearing, the rotating fan was seriously damaged, and we must purchase a new one. On 24th October, a large noise was generated from inside of the accelerator tank. We decided to open the tank and check the parts inside. The problem was also a bearing mounted in the power generator that supplies electric power to a terminal turbo-pump mounted inside the tank. We can get a new generator in a few weeks, because HVEE possessed one for spare by chance. We purchased it and replaced the damage generator on November. After tank opening, inner surfaces of the accelerator tank absorbed water in the atmosphere, we spent much time to remove water vapor from SF6 insulator gas. We had experienced twice of high voltage sparks, but no detectable damage occurred with the accelerator system. We could have restarted 14C measurements at around mid of December. Owing to these difficulties with the machine, the total number of graphite targets measured was 1634 in 2012, smaller in number than that in 2010 (1701), but a larger than in 2011 (1449).
名古屋大学年代測定総合研究センターシンポジウム報告

DOI： 10.18999/sumrua.24.13

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.60.0.101.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

近年、大気粉塵中の炭素粒子の発生源を推定する方法の一つとして、&lt;SUP&gt;14&lt;/SUP&gt;C濃度測定が注目されている。&lt;SUP&gt;14&lt;/SUP&gt;C濃度により、炭素成分の起源は化石燃料起源とバイオマス起源に分けられ、実際の粉塵試料に対し&lt;SUP&gt;14&lt;/SUP&gt;C濃度測定を行うことで、この２つの起源の寄与率が推定できる。また、δ&lt;SUP&gt;13&lt;/SUP&gt;Cも発生源特定の手がかりとして有効と考えられる。偏西風の風下に位置する福岡は、アジア大陸からの輸送による影響を受けやすい地点であるため、福岡の大気中微小粒子状物質に対し&lt;SUP&gt;14&lt;/SUP&gt;C濃度測定およびδ&lt;SUP&gt;13&lt;/SUP&gt;C測定を行うことは、近隣での発生および長距離輸送の実態解明につながると考えられる。本発表では、2012年度に福岡市で観測されたPM&lt;SUB&gt;2.5&lt;/SUB&gt;中全炭素(TC)における&lt;SUP&gt;14&lt;/SUP&gt;C濃度およびδ&lt;SUP&gt;13&lt;/SUP&gt;Cの通年の挙動について報告する。

DOI： 10.14862/geochemproc.60.0.112.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

本研究では，琵琶湖水が淡水リザーバー年代を示す原因を説明するために，湖水に対する古い炭素源の寄与を琵琶湖のシンプルな水理構造を利用してモデル計算を試みた。さらに，伊吹山系の湧水や姉川など河川水のDIC，DI14C濃度を測定し， Dead carbon sourceである伊吹山，霊仙山などの石灰岩地帯を起源とする河川水，地下水などから供給される古い炭素の影響を評価した。 豊富な魚介類や淡水を利用できるため，琵琶湖周辺では，先史時代から人々の生活が営まれていたことが知られている（水中遺跡は100ヶ所以上）。琵琶湖の水産資源を利用していた当時の（人間を含む）動物が，淡水リザーバー効果の影響を強く受けていたことが示唆される。発表では，現生生態試料を用いて，貝殻と（可食部である）身の炭素年代差，代表的な湖のリザーバー年代も含めて，考古学試料の炭素年代測定に関する淡水リザーバー効果の影響に関しても議論する。

DOI： 10.14862/geochemproc.60.0.226.0

CiNii Research

J-GLOBAL

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.60.0.61.0

CiNii Research

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOC JAPAN  

Geochemical mapping of Sr-87/Sr-86 ratios in Shikoku Island and the Kii Peninsula of Southwest Japan was performed using 233 samples of stream sediments (&lt;180 mu m). The spatial distribution of Sr-87/Sr-86 ratios successively increases from northern to southern geological units, with a gap at the Median Tectonic Line (MTL). In the Inner Zone divided by the MTL, a zone with Cretaceous granitoid rocks of the Ryoke Belt and sedimentary rocks of the Izumi Group, the Sr-87/Sr-86 ratios are measured at similar to 0.710. In the Outer Zone, a zone with Cretaceous metamorphic rocks of the Sanbagawa Belt and Jurassic to Miocene accretionary complexes of the Chichibu Belt and Shimanto Belts, the Sr-87/Sr-86 ratios tend to fall in the range from 0.706 to 0.715, tend to increase from north to south, and are highest in the youngest accretionary complex of the Southern Shimanto Belt.
The Rb-87/Sr-86-Sr-87/Sr-86 plots for stream sediments more clearly reveal the differences and similarities of their bedrocks, such as the different trends among the stream sediments of the Inner and Outer Zones. Samples collected from the Inner Zone show almost the same Rb-87/Sr-86-Sr-87/Sr-86 field as their source rocks, while most of the samples derived from accretionary complexes in the Outer Zone are plotted around a mixing line of older continental detritus and igneous-rock-derived materials. In light of the other geochemical characteristics observed, particularly the REE chemical features of the stream sediments and zircon ages in the basemental sedimentary rocks, the accretionary complexes in the Outer Zone may be mainly formed from the same source rocks, namely, igneous-rock-derived materials and continental detrital materials with different mixing ratios and a larger ratio of continental materials in the Southern Shimanto Belt. This study indicates that Sr-87/Sr-86 ratios of stream sediments strongly reflect the isotopic composition of the source rocks and are very useful for distinguishing the various geological and geochemical settings of the source rocks.

Web of Science

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.59.0.234.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.59.0.60.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

本研究では，縄文時代後半期，海産物に依存していた海岸近くに暮らしていた人々の生活を，遺跡出土土器に残存する有機物組成を用いて復元することを目的とする。愛知県渥美半島にある保美貝塚から出土した土器残存有機物の脂質組成から，土器で海産物を含む食材を煮炊きしていた可能性を強く支持する結果が得られた。この結果は，土器付着炭化物の年代測定結果から海洋リザーバー効果が検出され，付着炭化物の安定同位体組成から，海獣や海産魚類を調理した可能性が示唆されたことも調和的である。

DOI： 10.14862/geochemproc.59.0.333.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.59.0.331.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.59.0.132.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.59.0.218.0

CiNii Research

Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN ASSOC AEROSOL SCI & TECHNOLOGY  

Total suspended particles (TSP) were collected in spring (2011) in Nagoya and Fukuoka. The samples were analyzed for contents of inorganic ions, organic carbon (OC), and elemental carbon (EC), and delta C-13 value of total carbon. The results demonstrate that the calcium ion concentration and delta C-13 value of total carbon increased during the Asian dust storm events. In May 3, the ration of carbon derived from carbonate in total carbon was at maximum, and delta C-13 of total carbon showed the largest value. The results indicate that carbon derived from carbonate had been reacted with acidic species (such as H2SO4, HNO3 etc...) in the atmosphere during a long-range transport.

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Academy  

AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; <i>N</i> = 5) is about 90 ¹⁴C years older than that from the outer surfaces (4961 ± 22 BP; <i>N</i> = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.<BR><BR>(Communicated by Ikuo KUSHIRO, M.J.A.)

DOI： 10.2183/pjab.87.518

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Scopus

PubMed

CiNii Research

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

⁸⁷Sr/⁸⁶Sr, δ¹⁸O and δ¹³C isotopes of carbonate in calcareous sandstone show intermediate values between marine carbonate and silicate phase of the sandstone. The ⁸⁷Sr/⁸⁶Sr and δ¹⁸O isotopes indicate that these are the mixed ones of marine strontium and oxygen with those in silicate phase. Very little carbon is contained in the silicate phase and the δ¹³C value shows always that of marine. These data show conjunctive formations of the 1st-carbonate precipitation from seawater in the sandstone with 2nd-precipitation of carbonate by the quick reaction of silicates and the nascent carbon dioxide released at that time.

DOI： 10.14862/geochemproc.58.0.185.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.58.0.380.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

本研究では，礼文島浜中２遺跡Ｖ層出土土器胎土に残存する有機物をBristol大学で脂質分析し，海獣を起源とする有機残渣が検出されるかどうか検討した。その結果，炭素数14～22までの飽和脂肪酸が検出されると同時に，炭素数C16:3,18:3,20:3,22:3などのトリ不飽和脂肪酸（陸上動物や植物油と比べて，海洋性動物由来の油脂に占める割合は非常に高い）の加熱生成物と推定される環状化合物（ω-(o-alkylphenyl) alkanoic acids)が検出された。さらに，海洋性動物の存在の証拠と考えられているPhytanic acidやPristanic acidも検出された。このことは，縄文時代後期（1300～1200 BC）に，本遺跡で，これらの土器でニホンアシカを調理した際に，ニホンアシカの肉はコゲとして内面土器炭化付着物になり，燃料材に由来するススが外面土器付着炭化物として付着した。また，加熱によって生成するこれらの環状化合物は，土器でニホンアシカを調理した可能性を示唆する証拠であり，海洋性動物の指標として考えられるイソプレノイド化合物とともに土器に吸着され，現代検出されたものと考えられる。

DOI： 10.14862/geochemproc.58.0.300.0

CiNii Research

J-GLOBAL

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.58.0.314.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.58.0.137.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.58.0.114.0

CiNii Research

Publisher：日本化学会  

Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

For a preliminary test of C-14 dating of cremated human remains, we have collected charred bone and wood-charcoal fragments from cremated remains contained in cinerary urns that had been excavated from medieval Buddhist cemetery at the Hoenji temple in Aichi prefecture, central Japan. More than 230 urn vessels were discovered from the excavated area of ca. 14 m wide and 14 m long. The identification of charred bone or charcoal fragments among the remains was performed by observation of surface appearance, inspection of fine structures by a microscope, bubble formation during the HCl treatments in preparing target material for AMS C-14 dating, carbon and nitrogen contents, delta C-13 and delta N-15 values of the fragments. All C-14 ages obtained for the samples that were identified as charred bone remains were almost consistent with the archeological age estimated based on typological analysis of respective urns. On the other hand, some C-14 ages for the remains identified as wood charcoal, which had been produced from firewood or a wooden coffin during the cremation, were not consistent with archeological estimation, shifting toward older C-14 ages, most probably as the result of old wood effect. (C) 2009 Published by Elsevier B.V.

DOI： 10.1016/j.nimb.2009.10.080

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Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2010.0.543.0

CiNii Research

J-GLOBAL

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.57.0.167.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.57.0.35.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.57.0.277.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

先史時代の食生活を復元するために，飛行時間型二次イオン質量分析法（Time-of-flight secondary ion mass spectrometry：TOF-SIMS）を用いて，土器に残存する有機物分子を分子レベルで直接同定し（非破壊分析），調理された食材を推定することが可能であるかどうか検討した．

DOI： 10.14862/geochemproc.57.0.147.0

CiNii Research

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.210.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.259.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.63.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.205.0

CiNii Research

J-GLOBAL

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.129.0

CiNii Research

Language：Japanese   Publisher：Nagoya University  

DOI： 10.18999/sumrua.19.169

CiNii Books

Language：Japanese   Publisher：Nagoya University  

^<14>C abundances are measured across a weathering rind formed in Triassic calcareous sandstone. ^<14>C has not been detected by our sensitive AMS in the fresh sandstone, while about a half amount of the present ^<14>C is detected in the weathering rind of the sandstone. 14C is found to be a sensitive index of concrete weathering. The fresh concrete made from natural limestone does not contain any ^<14>C. Weathering in atmospheric condition will replace the dead carbon in the concrete with radiogenic ^<14>C and will be able to detect easily.

DOI： 10.18999/sumrua.19.66

CiNii Books

Language：Japanese   Publisher：Nagoya University  

Prehistrical human bone is used for ^<14>C dating and isotope palaeodietary analysis. Fossil bone tends to be suffered from exogenous contaminants and diagenetic alteration during burial, especially in tropical and wet areas, and the state of bone collagen preservation differs with each bone sample. Since bone sections in an individual have different internal structures, such as density, thickness, amount of spongins and compact bone, different sections could have various levels of diagenesis. In this study, we investigated whether collagen extracted from different sections of an individual has variations of C/N ratios, δ^<13>C and δ^<15>N values for different sections of an individual, and whether we can estimate its palaeodietary by analyzing one bone section of a whole individual. The samples used are eleven bone sections (cranium, sphenoid, tooth, rib, humerus, radius or ulna, the lower femur, the central femur, tibia and two back-bones) in an individual, nine sections in another, and seven sections in the other, collected from the Yuigahama-minami archealogical site, Kamakura, Japan. The surface of fossil samples were shaved and ultrasonicated repeatedly in distilled water, followed by HCl and NaOH treatments; then samples were lyophilized and pulverized. The powdered bone sample was treated with 0.6M-HCl in a cellulose tube in a beaker over 20h at 4℃. The decalcified bone sample was treated by 0.6M-NaOH followed by 1.2M-HCl and 0.6M-HCl. Gelatin was extracted from acid/alkali-insoluble residue by heating in distilled water for 12h at 80-90℃. Combusted gelatin was refined into N_2 and CO_2. These gases were used for carbon and nitrogen isotopic measurement by using an isotope ratio mass spectrometer (Finnigan, MAT252). Gelatin was wrapped into a Sn cup and measured for C/N ratios by using an elemental analyzer (Euro Vector, Euro EA3000). To estimate sample preparation-induced variation, seven gelatins were extracted from a bone section, and each measured for C/N ratios, δ^<13>C and δ^<15>N values. The deviations of δ^<13>C and δ^<15>N values for seven gelatins are ±0.1‰ and ±0.2‰, respectively. Most bone sections have gelatin yield of more than 0.7 wt%, and carbon yield of the combusted gelatin between 42 and 46 wt%. Bone with more than 0.7 wt% gelatin is generally well preserved, and collagens with around 40 wt% C are intact. The bone samples in this study, therefore, are well preserved and regarded as suitable for analysis. The C/N ratios of gelatins varied from 3.1 to 3.4 with different sections in an individual. The values show quality of the gelatin extractions because the good collagens have C/N ratios between 2.9 and 3.6. The δ^<13>C values of gelatins have variations of about 1‰, between -19.3 and -18.2‰, for different bone sections in an individual. The other two individuals have variations between -19.3 and -18.4‰, and -18.3 and -17.7‰. The δ^<15>N values have variations of about 1.5‰ (12.6〜14.0‰, 12.4〜13.1‰ and 12.6〜14.1‰, respectively) for different sections of each individual. There is a positive correlation between δ^<13>C and δ^<15>N values. The back-bones tend to have highest values, and the rib and tooth have a little higher values than the others. ^<14>C ages have no variation in different sections. It means exterior organic substance don't get mixed in gelatin.

DOI： 10.18999/sumrua.19.117

CiNii Books

Publisher：Nagoya University  

To answer a question whether ^<14>C concentration is higher for plants growing at high altitude locations than those growing at the sea level, we recently have collected plants samples from four sites at different altitudes: (1) plants from Lake Pumayum area at the altitude of 5030m; (2) plant samples from the suburbs of Lhasa city at the altitude of 4000m; (3) needle leaves from pine tree at 2600m-high location of Mt. Fuji; and (4) needle leaves from pine trees growing in the Higashiyama Campus of Nagoya University. The plant samples were rinsed with distilled water, treated chemically by an acid- alkali-acid treatment, and finally dried in an electric oven. A part of the samples were combusted to produce CO_2 and the produced CO_2 was changed to graphite for ^<14>C measurements with an AMS ^<14>C system at Nagoya University. The measured ^<14>C concentration was given in a ratio of sample ^<14>C/^<12>C to that of standard. For both sample and standard, isotopic fractionation was corrected. In addition, the decrease of ^<14>C concentration by radioactive decay for a standard from AD1950 to the year of sample collection was also corrected. ^<14>C concentrations were highest for the plant samples from Lake Pumayum showing a value of 1.081±0.016 in average, followed by the values of 1.055±0.005 for plants near Lhasa city, the values of 1.051±0,002 for plants from Mt. Fuji, and finally 1.017±0.003 for pine needles from Nagoya University. This clear altitude dependence may be explained preferably by Suess effect that is a dilution effect of modern ^<14>C concentration with dead carbon, containing no ^<14>C, produced by combustion of fossil fuel. The estimated altitude dependence of ^<14>C atom production is not strong and the resulting altitude dependence of ^<14>C concentration of CO_2 can fade out quickly by the strong air-mass mixing in the troposphere.

DOI： 10.18999/sumrua.19.110

Publisher：Nagoya University  

Umi is located along the Kamimura River within the Kamiyahagi area of southeastern Ena City, Gifu Prefecture. The name 'Umi' means sea or large lake; however, there are no lakes in the mountainous Kamiyahagi area. The Tokai Gou (torrential rain) flood of September 11-12, 2000 destroyed embankments along the river, and exposed sedimentary layers that are typical of a lacustrine depositional setting. This confirms the existence of a paleo-lake from which the name Umi originated. The ^<14>C ages, ranging from 280±37 to 345±25 BP, appear to be contemporaneous with Tensho Earthquake that occurred in central Japan on January 18, 1586.

DOI： 10.18999/sumrua.19.26

Language：Japanese   Publisher：Nagoya University  

We investigated the relationships between climatic factors and annual tree-ring data such as stable carbon isotopic composition and tree-ring width of a Japanese pine tree (Pinus thunbergii) with annual rings from 1955 to 2002, which was collected at the site of Environmental Studies Hall in Nagoya University. The climatic factors used are: month total values of sunshine duration and precipitation, month average values of day average temperature, relative humidity and vapor pressure in the Nagoya area. The annual rings of the sample are very wide in the periods from 1960-1970. This remarkable growth might be related with the local environment changes not with the regional environment changes because the annual-ring width shows no correlation with the climatic factors. The δ^<13>C fluctuations of the annual rings in the period from 1955 to 1979 are different from those in the period from 1980 to 2002. The result shows the change factors of δ^<13>C values in the two periods are different. In the period from 1955 to 1979, no-climatic environmental factors, that is, artificial factors such as air pollution effect the δ^<13>C fluctuations because they are not related with the climatic factors. In the period from 1980 to 2002, on the other hand, the month average values of relative humidity are good correlative with the δ^<13>C fluctuations of earlywood and latewood fractions, relatively.

DOI： 10.18999/sumrua.19.175

CiNii Books

Publisher：Nagoya University  

Furukawa Memorial Hall is now under earthquake-proof construction and we are performing measurement of vibration caused by the construction to evaluate the influence given to a Tandetron Accelerator Mass Spectrometer and two CHIME machines installed in Furukawa Memorial Hall. In this report we described about the monitoring points of vibration and measurement equipments used for vibration measurement.

DOI： 10.18999/sumrua.19.190

Language：Japanese   Publisher：Nagoya University  

A second ^<14>C-AMS system (Model 4130-AMS), built by High Voltage Engineering Europe (HVEE), B.V., The Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests were completed in January of 1999, and routine measurements began in mid-2000. Since completion of the acceptance tests in early 1999, we have encountered a lot of troubles with the machine, particularly in 2002. Since the end of 2002, the machine has relatively worked well, expect for minor problems. However, since June in 2006, we had a serious problem with the high voltage generation system. We opened the accelerator tank twice, in October of 2006 and July of 2007, and replaced each time totally 154 diodes and 5 resistors, 230 diodes and 5 resistors, respectively, for the high-voltage generator system used to rectify the AC power source and stabilize the DC current. Thus the number of targets measured was 1384 in 2007, which was almost the two-third of that in normal year. We also encountered troubles with (1) spark-oriented damage of a high voltage controller module, (2) a cooling system of the power generator for the analyzing magnets both for high energy and low energy beams. The cooling-water flow for the power generator was disturbed by chemical deposits in water tubes, and was not plenty enough to cool down the generator. A thermo-switch stopped the generator for safety and thus we could not operate the analyzing magnets. We replaced the damaged tubes to new ones. This trouble also limited the number of targets measured. Since November 1^<st>, 2007, we had a scheduled shutdown of the AMS system, owing to the improvements of the building, Furukawa Memorial Hall, against earthquake invasion expected in near future around Tokai area, central Japan, In April of 2008, we will start ^<14>C measurements again, possibly in a new good condition of the building.

DOI： 10.18999/sumrua.19.39

CiNii Books

Publisher：Nagoya University  

For combustion of samples a closed tube-combustion (CTC) method has been generally and widely used until now, but this method takes much time and labor. Recently we have investigated a CO_2 production and purification system using a commercial elemental analyzer (EA) connected to cryogenic traps, which enables fast combustion and CO_2 purification of samples. We compared δ^<13>C values between closed tube- and elemental analyzer-combusted samples of Oxalic Acid-II (new oxalic acid standard distributed by NIST; SRM4990c) and almost ^<14>C-free oxalic acid (Kishida[○!R]). For the CTC method δ^<13>C measured values tend to increase as sample amount is small relative to CuO amount. This might be due to absorption of more ^<12>C than ^<13>C to an inner wall of Pyrex tube and/or CuO. Furthermore, different δ^<13>C is observed by addition of Sulfix[○!R] to small amount of CO_2. δ^<13>C values measured by the EA method show good agreement with the results using the CTC method, and sample preparation background of ^<14>C is higher in the CTC method than the EA method, suggesting that this newly developed EA system shows high precision and accuracy. However, more detailed study and improvement on the EA system will be needed for different amounts of various standards such as IAEA standards.

DOI： 10.18999/sumrua.19.160

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.55.0.382.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.55.0.325.0

CiNii Research

Language：Japanese   Publisher：ELSEVIER SCIENCE BV  

A diverse assemblage of indigenous carbonaceous microstructures, classified here as highly probable microfossils to pseudomicrofossils, is present in the &gt;ca. 2.97 Ga Farrel Quartzite (Gorge Creek Group) at Mount Grant and Mount Goldsworthy, Pilbara Craton, Western Australia. The microstructures are an integral part of the primary sedimentary fabrics preserved in black chert beds. The interbedding of chert with layers of large silicified crystal pseudomorphs and fine to coarse grained volcaniclastic/clastic beds indicate deposition in a partially evaporitic basin with terrigenous clastic and volcaniclastic input.
Similar associations of microstructures are present at the same stratigraphic level in outcrops more than 2 km apart. Four major microstructural types are present: thread-like, film-like, spheroidal and lenticular to spindle-like, each of which can be further subdivided into several sub-types. Most of the microstructures were deposited as part of an assemblage of chemical and clastic sediments, although there are some thread-like microstructures present for which a synsedimentary origin cannot be confirmed. Many specimens appear to have originally had flexible but breakable walls and some occur in colony-like aggregations. Size distributions for the four major types are generally narrow, a feature typical of biogenic structures. The microstructures are composed of disordered carbon (as revealed by Raman spectroscopy) and the bulk isotopic composition of the carbon is delta C-13&lt;-30per mil, which is consistent with biological processing.
The combined morphological and geological evidence suggests that the film-like structures, small spheres associated with films, large spheroids and spindle-like structures are probable to highly probable fossil remains of microorganisms. The morphological variety among the microstructures suggests that a diverse microbial ecosystem flourished in the Pilbara region during the Archaean. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.precamres.2007.03.006

Web of Science

Scopus

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

An AMS system dedicated to C-14 measurement (486-AMS) built by HVEE BN. The Netherlands, was delivered to Nagoya University in 1996, and is in use for routine C-14 measurements. The relative error of the standard deviation (1 sigma) of C-14/C-12 ratios is 10.3% to +/- 0.5% (somewhat larger than the uncertainty of +/- 03% from C-14 counting statistics) and that of the corresponding C-13/C-12 ratios is +/- 0.03% to +/- 0.07%, as measured for HOxII standards. By using this AMS system, we are now testing whether the recommended IntCa104 C-14 calibration data set is consistent with the natural C-14-concentration variations as recorded in Japanese trees. Here we report the results of these consistency tests and accurate age determination of tree rings grown in Japan, using the C-14 wiggle matching technique. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2007.02.005

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Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Paired marine and terrestrial samples were collected at archeological shell mounds in Kagoshima, Saga and Aichi prefectures and selected from sediment samples bored at the Mawaki archeological site in Ishikawa prefecture, to evaluate the local marine reservoir effect in Japan. The local reservoir corrections, Delta R, were evaluated to be 8 +/- 110 and - 178 +/- 113 C-14 years for Miyasaka shell mound, - 125 +/- 50 to -45 +/- 49 and -86 +/- 48 to -21 +/- 50 C-14 years for Higashimyo shell mound, -46 +/- 52, 40 +/- 44, -136 +/- 44 and 100 + 44 14C years for Yoshigo shell mound, -255 +/- 38 and - 146 +/- 46 C-14 years for Kuzubasama shell mound, -71 +/- 33, -30 +/- 85 and -78 +/- 74 C-14 years on average for C4, C5 and C6 cores, respectively, from the Mawaki site. The existing data along with the present results suggest that the Delta R values obtained for central to southern part of Japan are consistent with zero or a bit negative, but are different from the Delta R values of 200 to 500 C-14 years for the northern parts of the Japanese archipelago. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2007.01.186

Web of Science

Scopus

Publisher：名古屋大学年代測定資料研究センター  

第19回名古屋大学年代測定総合研究センターシンポジウム平成18(2006)年度報告<第1部> Proceedings of the 19th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research\in 2006 日時:平成19 (2007)年1月15日(月)～17日(水) 会場:名古屋大学シンポジオン Date:January15th-17th, 2007 Venue:Nagoya Uhiversity Symposion Hall

DOI： 10.18999/sumrua.18.55

Publisher：名古屋大学年代測定資料研究センター  

第19回名古屋大学年代測定総合研究センターシンポジウム平成18(2006)年度報告<第1部> Proceedings of the 19th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research\in 2006 日時:平成19 (2007)年1月15日(月)～17日(水) 会場:名古屋大学シンポジオン Date:January15th-17th, 2007 Venue:Nagoya Uhiversity Symposion Hall

DOI： 10.18999/sumrua.18.31

Publisher：名古屋大学年代測定資料研究センター  

第19回名古屋大学年代測定総合研究センターシンポジウム平成18(2006)年度報告<POSTER SESSION> Proceedings of the 19th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research\in 2006 日時:平成19 (2007)年1月15日(月)～17日(水) 会場:名古屋大学シンポジオン Date:January15th-17th, 2007 Venue:Nagoya Uhiversity Symposion Hall

DOI： 10.18999/sumrua.18.83

Language：English   Publisher：Nagoya University  

DOI： 10.18999/sumrua.18.53

CiNii Books

Language：Japanese   Publisher：Nagoya University  

Prehistrical human bone is used for ^<14>C dating and isotope palaeodietary analysis. Fossil bone tends to be suffered from exogenous contaminants and diagenetic alteration during burial, especially in tropical and wet areas, and the state of bone collagen preservation differs with each bone sample. Since bone sections in an individual have different internal structures, such as density, thickness, amount of spongins and compact bone, different sections could have various levels of diagenesis. In this study, we investigated whether collagen extracted from different sections of an individual has variations of C/N ratios, δ^<13>C and δ^<15>N values for different sections of an individual, and whether we can estimate its palaeodietary by analyzing one bone section of a whole individual. The samples used are eleven bone sections (cranium, sphenoid, tooth, rib, humerus, radius or ulna, the lower femur, the central femur, tibia and two back-bones) in an individual, nine sections in another, and seven sections in the other, collected from the Yuigahama-minami archealogical site, Kamakura, Japan. The surface of fossil samples were shaved and ultrasonicated repeatedly in distilled water, followed by HCl and NaOH treatments; then samples were lyophilized and pulverized. The powdered bone sample was treated with 0.6M-HCl in a cellulose tube in a beaker over 20h at 4℃. The decalcified bone sample was treated by 0.6M-NaOH followed by 1.2M-HCl and 0.6M-HCl. Gelatin was extracted from acid/alkali-insoluble residue by heating in distilled water for 12h at 80-90℃. Combusted gelatin was refined into N_2 and CO_2. These gases were used for carbon and nitrogen isotopic measurement by using an isotope ratio mass spectrometer (Finnigan, MAT252). Gelatin was wrapped into a Sn cup and measured for C/N ratios by using an elemental analyzer (Euro Vector, Euro EA 3000). To estimate sample preparation-induced variation, seven gelatins were extracted from a bone section, and each measured for C/N ratios, δ^<13>C and δ^<15>N values. The deviations of δ^<13>C and δ^<15>N values for seven gelatins are ±0.1‰ and ±0.2‰, respectively. Most bone sections have gelatin yield of more than 0.7 wt%, and carbon yield of the combusted gelatin between 42 and 46 wt%. Bone with more than 0.7 wt% gelatin is generally well preserved, and collagens with around 40 wt% C are intact. The bone samples in this study, therefore, are well preserved and regarded as suitable for analysis. The C/N ratios of gelatins varied from 3.1 to 3.4 with different sections in an individual. The values show quality of the gelatin extractions because the good collagens have C/N ratios between 2.9 and 3.6. The δ^<13>C values of gelatins have variations of about 1‰, between -19.3 and -18.2‰, for different bone sections in an individual. The other two individuals have variations between -19.3 and -18.4‰, and -18.3 and -17.7‰. The δ^<15>N values have variations of about 1.5‰ (12.6〜14.0‰, 12.4〜13.1‰ and 12.6〜14.1‰, respectively) for different sections of each individual. There is a positive correlation betweenδ^<13>C andδ^<15>N values. The back-bones tend to have highest values, and the rib and tooth have a little higher values than the others.

DOI： 10.18999/sumrua.18.73

CiNii Books

Language：Japanese   Publisher：Nagoya University  

A second ^<14>C-AMS system (Model 4130-AMS), built by High Voltage Engineering Europe (HVEE), B.V, The Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests were completed in January of 1999, and routine measurements began in mid-2000. Since completion of the acceptance tests in early 1999, we have encountered a lot of troubles with the machine, in particular in 2002 (see Fig.1). Since 2002, the machine has relatively worked well, expect for minor problems. However, it should be stressed that even a minor malfunction, ^<14>C measurements are not possible with the system. In fact, the AMS machine was in good condition in the early half of 2006. However, since June in 2006, we had a serious problem with the high voltage generation system. We opened the accelerator tank in October and replaced totally 154 diodes and 5 resistors for the high-voltage generator system used to rectify the AC power source and stabilize the DC current. Thus the number of targets measured was 1115 in 2006, which is almost the half of that in normal year. We also encountered a trouble with a cooling system of the power generator for the analyzing magnets both for high energy and low energy beams. The cooling-water flow for the power generator was disturbed by chemical deposits in the water tube, and was not enough to cool down the generator. Thermo-switch stopped the generator for safety and thus we could not operate the analyzing magnets. We replaced the damaged tubes to new ones. This trouble also limited the number of targets measured.

DOI： 10.18999/sumrua.18.91

CiNii Books

Publisher：Nagoya University  

During the past several decades, many medieval skeletons were excavated from archaeological sites in the Yuigahama area, Kamakura, Japan. The excavations yielded more than 5,000 individuals in varying states of preservation from the Zaimokuza, Seiyokan, Yuigahama-minami and Chusei Shudan Bochi sites. Medieval Kamakura was an ancient capital of the Kamakura Shogunate, and a lot of people lived in Kamakura with high population density. The human skeletons excavated from the Zaimokuza site are reported to be humans dead by competition at the end of the Kamakura Shogunate, but a detailed study on dating of the human skeletons has not made yet. In this study, we measured ^<14>C ages, together with carbon and nitrogen isotope ratios, of human skeletal remains excavated from the Yuigahama-minami site and Chusei Shudan Bochi site. The δ^<13>C and δ^<15>N were not different between human skeletal samples of both sites, while the ^<14>C ages were different between them: The human bones of the Yuigahama-minami site are 100 year younger than those of the medieval collective-cemetery site. All of ages of human skeletons from both of the sites are older than the latest Kamakura period. The δ^<13>C and δ^<15>N values of the medieval Kamakura people are higher than those of terrestrial mammals, indicating that they exploited some amount of marine fish and/or mammals with higher δ^<13>C and δ^<15>N as protein sources. Therefore, the ^<14>C ages obtained for human skeletons could be order than the true ages. ^<87>Sr/^<86>Sr isotopic ratios of human skeletons of the Yuigahama-minami site tend to be higher than those of the Chusei Shudan Bochi site. Soils, plants and animals feeding on them in a given locality have ^<87>Sr/^<86>Sr values that generally mirror underlying bedrock composition, and thus ^<87>Sr/^<86>Sr ratios of human skeletons are useful tools for assessing migration in prehistory. The result obtained in this study suggests that Yuigahama-minami humans and Chusei Shudan Bochi humas lived in different areas. More skeleton samples should be analyzed for determining detailed ^<14>C ages of humans excavated from the Yuigahama sites, and for estimating migration of prehistory of the medieval Kamakura humans.

DOI： 10.18999/sumrua.18.134

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

To evaluate whether 87Sr/86Sr ratio of a bone reflects 87Sr/86Sr ratio of the birth- and growth-places, two bone samples, together with the geological samples in their birth- and growth-places, were measured for 87Sr/86Sr ratios by TIMS. The samples used are a boar collected at Asuke, Toyota City, Aichi prefecture, and a black bass collected from Lake Biwa. The 87Sr/86Sr ratio of the boar bone was 0.71001±0.00002, while those of stream sediments in the Asuke area was around 0.710. The 87Sr/86Sr ratio of the black bass bone was 0.71215±0.00002, while those of surface water at the southern basin in Lake Biwa was 0.71233±0.00002. The similar 87Sr/86Sr ratios between bone and its provenance geology indicates that the 87Sr/86Sr ratio of bone reflects the isotopic ratios of the birth- and growth-places.

DOI： 10.14862/geochemproc.54.0.203.0

CiNii Research

Language：Japanese   Publisher：Atomic Energy Society of Japan  

DOI： 10.11561/aesj.2007s.0.66.0

CiNii Research

Publisher：Geochemical Society of Japan  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Geochemical and petrological analyses of Archean clastic metasedimentary rocks at Mt. Goldsworthy in the Pilbara Craton, Western Australia reveal the early evolution of continental crust and the Earth's surface environment. The succession correlative to the ca. 3.4 Ga Strelley Pool Chert is composed dominantly of silicified medium-grained to very coarse-grained sandstone, siltstone and shale, with minor chert and precipitative beds of nahcolite and barite. The sandstone is generally rich in detrital quartz, with the coarse-grained sandstone containing abundant, very well rounded mono-crystalline quartz that is assumed to be derived from older sedimentary rocks. The recycled detritus is mixed with first-cycle detrital material such as feldspar and barite that is sourced from reworked precipitative beds. The sandstone also contains zircon, Fe-Ti oxides, sulfides and lithic fragments of various origins including mafic-ultramafic volcanic rocks, sedimentary and possibly metamorphic rocks.
Al-Ti-Zr systematics indicates that the source area for the Mt. Goldsworthy clastic metasedimentary rocks was locally subjected to hydrothermal alteration. Reaction with the acid solution resulted in Al-dissolution and the formation of Zr- and Ti-enriched residual detrital material. The enrichment in heavy rare earth elements and low Al2O3/TiO2 values of Mt. Goldsworthy samples reflects the inflow of the residual zircon- and Ti-oxides-enriched detritus. Th/Sc, La/Sc and Eu/Eu-* ratios that are unaffected by contamination by the residual detritus indicate a mixed provenance with a significant contribution from granitoid rocks. The presence of detrital zircon older than 3.5 Ga was also demonstrated in this study. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.precamres.2006.02.006

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Publisher：名古屋大学  

Geochemistry and Cosmochemistry Laboratory, Nagoya University, started a geochemical mapping project in 1994 to make environmental assessment of the Chubu area in Japan. During ten years from 1994 to 2004, stream sediment samples of 1,563 were collected in the northeastern parts of Aichi Prefecture. Major element data of these samples by X-ray fluorescence spectrometry (XRF) and the discussion on their regional spatial distributions have been published. Here we report 22 element analysis (Sc, Cr, Fe, Co, Zn, As, Rb, Sb, Cr, Ba, La, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au, Th and U) of the sediment samples by instrumental neutron activation analysis (INAA), together with discussion on the accuracy and precision of our analytical method by INAA. A new automated γ-ray counting and data processing system for INAA and postaldelivery system of irradiated samples from Japan Atomic Energy Research Institute were utilized. The INAA system enables us simple and rapid INAA analysis of a large number of samples. By using this system, nine GSJ rock reference samples (JB-1a, JB-2, JA-1, JG-1a, JG-2, JLk-1, JSd-1, JSd-2 and JSd-3) and one USGS rock standard G-2 were analyzed to examine accuracy and precision of analytical results. The results show good agreement with the reference values, indicating that our analytical system is effective for analysis of stream sediments with various bedrock geology. On the other hand, in order to evaluate accruracy of the values obtained by INAA, comparison of analytical results of stream sediments by INAA with the previously analyzed data by inductively coupled plasma atomic emission spectrometry (ICP-AES), atomic absorption spectrometry (AAS) and XRF was made. The result indicates that the data by the ICP-AES and AAS methods, which need HF digestion of samples, could be lower than the true values for some elements due to partly incomplete decomposition of samples. The INAA method, which needs no HF digestion, is suitable for accurate analysis for a large number of samples in the geochemical mapping project. We have collected stream sediments collected at the same site every year since 1994 to 2004. The samples were used to evaluate sample heterogeneity of the sediment collected at the same site. Most of trace elements, except for Cr, Zn, Hf and Au, of the samples show the concentrations with ±(30～50)% deviations, a little larger than the analytical errors. The Cr, Zn, Hf and Au concentrations have larger deviations, indicating the heterogeneous distribution of small accessory minerals at the sampling site and even in sample aliquots of 100 mg.国立情報学研究所で電子化したコンテンツを使用している。

DOI： 10.18999/joueps.53.15

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Gold, arsenic and antimony appear together in hydrothermally altered area. However, Au exists very little in the eastern part of Inuyama-city, although high As concentrations are observed. There might be different mechanism of elemental concentration in As and Au from hydrothermally altered area. In this study, we collected 101 stream sediments in Inuyama-city, Aichi Prefecture, and determine major elements and trace elements that included As ,Sb and Au. We drew the geochemical map of these elements and discuss mobility of elements in Mesozoic and Paleozoic area.

DOI： 10.14862/geochemproc.53.0.136.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.53.0.98.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.53.0.224.0

CiNii Research

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Techniques have been developed to measure Sr isotopic composition and concentration on a single sample aliquot in rock and water samples with ⁸⁴Sr-concentrated spike. A single TIMS measurement of the Sr sample yielded both isotopic composition and concentration after decomposition of mixture of sample and ⁸⁴Sr spike. Standard solutions with different Sr concentrations, made form Johnson-Matthey Specpure SrCO₃ (99.999%), were added by appropriate amount of 84Sr spike solution, and determined the Sr isotopic composition and concentration. The single measurement was adopted to water samples of an Indian river and standard rocks such as JP-1 and JCh-1. We will report the results.

DOI： 10.14862/geochemproc.52.0.273.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Lake sediment cores in Lake Biwa, collected from the northern and southern basins, respectively, were measured for carbon content, d¹³C, and d¹⁴C. Acid-alkali-insoluble fraction (residue) and acid-soluble fraction obtained by acid-alkali-acid treatment of the sediments were analyzed. The sediments in rivers flowing in Lake Biwa were also measured for C content and d¹³C of residue and acid-soluble fractions. The d¹³C and d¹⁴C values of residue were higher than those of acid-soluble fraction. We will report the difference, together with the result of different chemical behaviors of sediments in the northern and southern basins.

DOI： 10.14862/geochemproc.52.0.170.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.52.0.105.0

CiNii Research

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

We measured D/L aspartic acid ratios and radiocarbon ages of a Mammoth molar fossil collected from Bykovsky Peninsula, eastern Siberia. Four parts of dentin, enamel, cement and root in the molar fossil were analyzed for gelatins and XAD-treated hydrolysates. The ¹⁴C ages of four parts are different, and the gelatins have 1000-2000 year older ages than the XAD-treated hydrolysates, expect for the root part. It is thought that the Molor fossil is dated about 37,000 BP. The D/L aspartic acid ratio of the molar fossil is low, and it suggests that amino acids in the Mammoth molar have not racemized since it was dead and buried. This result is well consistent with the fact that it was preserved in the permafrost.

DOI： 10.14862/geochemproc.51.0.110.0

CiNii Research

Web of Science

Web of Science

Web of Science

Web of Science

Web of Science

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.50.0.31.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

陸域の金属元素の主なリザーバは岩石圏にあり、風化、侵食により土砂や溶存態に形を変え、河川、沿海、外洋へと移動、拡散していく。現代においては、人為的な森林伐採や丘陵地開発による侵食の加速、人間活動による金属物質の放出もある。これらの様々な要因が複合的に絡まり河川水や海水、堆積物の元素組成が決まっているが、その要因をひとつひとつ紐解くにはその起源の情報を与えてくれる同位体は有力な指標である。本講演では、愛知県北東部地域から採取された150の河川堆積物試料と15の基盤岩岩石試料中の微量金属元素ストロンチウムの同位体比から得られる地圏環境情報について報告する。

DOI： 10.14862/geochemproc.50.0.63.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Geochemical map is a useful tool for geoenvironmental assessment. 27 minor elements were examined for 1500 stream sediment of Aichi Prefecture, Japan. Most of the elemental distribution patterns are considered as an effect of basement geology. Some of the high Fe distribution ,however, are correlated with golf cource. Gold and arsenic distribution seems be a result of geothermal activities.

DOI： 10.14862/geochemproc.50.0.62.0

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

Geochemical and Cosmochemical Laboratory, Nagoya University, has started a geochemical mapping in 1994, in order to make a geo-environmental assessment of Aichi Prefecture, central part of Japan.The analyses suggest that the stream sediments from areas with sedimentary rock basement are more enriched in SiO2 than those from areas with granitic basement. This SiO2 enrichment can be ascribed to the wide distribution of siliceous sedimentary rocks such as bedded cherts in their hinterland, the Mino Terrane. Samples from the area in the granitic basement are characterized by enrichment of Na, K, and Ca. The relative abundance of these elements, however, differs in the respective granitic bodies. This difference reflects the difference of abundance and chemical composition of plagioclase and potassium feldspar in stream sediments. Therefore, the major elements examined here reflect natural geo-environment and geochemical map may be useful as a supporting data for geological mapping.

DOI： 10.14862/geochemproc.50.0.61.0

CiNii Research

J-GLOBAL

Web of Science

Publisher：Nagoya University  

A Tandetron accelerator mass spectrometer (Tandetron-I AMS system), an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Center for Chronological Research (CCR), Nagoya University. In the meanwhile, a so-called second generation AMS ^<14>C apparatus (Tandetron-II AMS system) manufactured by High Voltage Engineering Europe, BV, the Netherlands has been installed successfully at CCR in 1997. Though we had experienced a lot of difficulties with the Tandetron-II just two years after its installation, we were able to start ^<14>C measurements with the machine in acceptable precision since the end of 1999. The ^<14>C measurement error (one sigma error)of the Tandetron-II is around ±20 - ±40 years, which is clearly smaller than that of the Tandetron-I (around ±50 - ±90 years). In addition, the reproducibility tests of ^<14>C measurements for the IAEA C1- C8 ^<14>C standards suggest that accuracy of ^<14>C measurement can be as good as around 0.5% We participated the Forth International Radiocarbon Intercomparison (FIRI) program started in 1999,after its set up at the time of the 15^<th> International Radiocarbon Conference at the University of Groningen, the Netherlands, in 1997. In the FIRI program, 10 samples of different materials were distributed to 92 ^<14>C laboratories of three different ^<14>C detection methods (25 AMS labs., 18 GPC labs. and 49 LSC labs.) from 37 different countries. Our AMS group of Nagoya University is one of the 25 AMS labs. The FIRI results have been reported preliminarily at the Edinburgh workshop on March 2001. We can also get the results by the web site of Radiocarbon (www. radiocarbon. org). We briefly summarize the report in relation with our own results, which are consistent with the mean values of ^<14>C results reported from 25 AMS labs.

DOI： 10.18999/sumrua.13.29

Publisher：Nagoya University  

To investigate the best HCl concentration used for decalcification of a fossil bone without loss of bone organic fractions, various concentrations of 0.4M, 0.6M, 0.8M, 1.0M and 1.2M HCl were examined to analyze carbon, nitrogen and radiocarbon isotopes. The bone used in the experiment is a fossil fragment collected from the Awazu submarine archeological site, Shiga. The yield of insoluble decalcified fractions does not change in the range from 0.4M to 1.0M HCl, and it decreases on 1.2M HCl. The result suggests that a part of bone organic fractions departs from the decalcified fractions by treatment of higher HCl concentration. The ^<14>C age for gelatin collagens does not change on any concentrations of 0.4M, 0.6M, 0.8M and 1.2M HCl, and could be reliable because the XAD-2 treated hydrolysate fraction shows the same ^<14>C age. Therefore, 0.4M is the best concentration of HCl to efficiently decalcify the fossil fragment in this study. The fossil bone used in this study is well-preserved, and the above best condition of decalcification does not apply to another poorly-preserved fossil bones. It could be, however, suitable to decalcify and fossil bone with 0.4M HCl in a cellulose tube.

DOI： 10.18999/sumrua.13.177

Publisher：Nagoya University  

A sediment core in the southern Lake Biwa was analyzed for ^<210>Pb, ^<137>Cs and Sr isotope ratio. The sedimentation rate of the lake sediments assumed by ^<210>Pb is about 3mm/y. 137Cs, a fallout product from atmospheric nuclear weapon tests, shows maximum activity at 9.5cm depth. Maximum fallout of ^<137>Cs to water and land occurred during 1963-1964,and the sedimentation rate assumed by ^<137>Cs is also about 3mm/y. The sedimentation rate of 3mm/y, however, could be untrue because surface sediments are disturbed and mixed by physical turbulence. Sr isotope ratios of the lake sediments radically change from 0.7185 to 0.7198,and Sr concentrations also radically change from 73ppm to 64ppm at near 10cm depth. Therefore, the following causes are expected : 1) Sr system has changed by artificially environment pollution since near 1960,and 2) surface sediments are disturbed and mixed by physical turbulence. In the case of 2), the profiles of ^<210>Pb and ^<137>Cs lead to mixing process except sedimentation process. The profiles of other nuclides such as ^<14>C and ^<90>Sr would help better understanding of the behavior of lake sediments. It is necessary to analyze another sediment cores of southern and northern Lake Biwa.

DOI： 10.18999/sumrua.13.71

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.49.0.209.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.49.0.187.0

CiNii Research

Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.49.0.142.0

CiNii Research

Publisher：Nagoya University  

We measured ^<14>C ages, carbon and nitrogen stable isotopic ratios of gelatin-collagens extracted from deer and human bones at British Columbia, Canada. The deer bone samples, samples #1〜#3,come from a site in the interior of British Columbia, designated as DhRa-02 site. The human bone samples, samples #4〜#6,are from the Pender Canal site, on North Pender Island, British Columbia. In general, reliable ^<14>C ages, carbon and nitrogen stable isotopic ratios can be obtained for collagens extracted from fossil bones, provided that the collagens have been preserved well from weathering in nature. Experimental yields of gelatin-collagens were higher than 0.7%, except for sample #1 with 0.25%. For sample #1,we tried to extract amino acid fractions by hydrolyzation and XAD-2 treatment and to measure its ^<14>C age. The age is the same as that of gelatin-collagen, about 1200 yrBP. Samples #1 and #2 are situated stratigraphically above a volvcanic ash, identified as Mazama tephra ca 6800 yrBP, and have post-ash dates, 1260 and 3010 yrBP, respectively. Sample #3 shows 3820 yrBP, younger than the age of Mazama tephra, though #3 comes from a pre-ash layer. Samples #4〜#6 have relatively high gelatin yields of 6〜9%, and show the ^<14>C ages of 3120〜3550 yrBP. The CO_2 yields from the gelatin-collagens of samples #1〜#6 are over 41%, consistent with the value of 40〜50% for gelatin-collagen extracted from fresh bones. Thus, the ^<14>C ages, carbon and nitrogen stable isotopic ratios obtained for the gelatin-collagens seem to be reliable. The deer bone samples #1〜#3 demonstrate δ^<13>C value of 〜-21‰ and δ^<15>N value of +5〜+8‰, which are the values of C3 millets. On the other hand, the human bone samples #4〜#6 show relatively high δ^<13>C value of -13‰ and δ^<15>N value of +18‰. It is thought that they ate marine products such as fishes and shellfishes, with δ^<13>C value of -15〜-20‰ and δ^<15>N value of +15〜+20‰, when they were alive. The high δ^<13>C and δ^<15>N values for the human bones are caused by the food resources.

DOI： 10.18999/sumrua.12.169

Publisher：Nagoya University  

Terrestrial age of meteorites gives us important informaion to estimate the terrestrial history of the meteorites. With the advent of AMS, the required sample mass of meteorite for measurement has been reduced as small as 0.1g. As a result, many more ^<14>C measurements have been performed intensively by the Toronto AMS group, Canada, the Arizona AMS group, USA, and so on. In Japan, AMS ^<14>C measurements of meteorites have been scarcely performed, to our regret. We have constructed a system to extract carbon from meteorites using a vacuum-tight RF melting method in order to study ^<14>C activities in meteorites, in a similar method used by the Arizona group. A meteorite powder sample mixed with pure iron chips is combusted in a RF furnace (Leco HF-10) in the presence of purified carbon-free oxygen in a closed vacuum-tight glass line system. The sample gases evolved are passed through MnO_2 and Pt/CuO traps, and then the CO_2 is separated in a liq.N_2 trap, by pumping out oxygen completely. The amount of ^<14>CO_2 is determined by a pressure transducer in a certain volume and diluted with a known amount of ^<14>C-free CO_2. The total CO_2 is graphitized by reducing with hydrogen in a Fe-powder catalyst and the produced graphite is measured of its ^<14>C concentration with a Tandetron accelerator mass spectrometer at the Center for Chronological Research, Nagoya University. Terrestrial ^<14>C ages of two Antarctic meteorites, Y-75102 from the Yamato icefield, ALH-77294 and ALH-77262 from the Allan Hills icefield, were determined. The age of Y-75102 is estimated 4.0±1.0 ka, the age of ALH-77294 is 19.5±1.2 ka, and the age of ALH-77262 is 28.5±0.9 ka. The ^<14>C ages on the meteorites roughly agree with the literature value. However, the results of the small-counter method (Fireman, 1983; Fireman and Norris, 1981) tend to be oldest, the results of the AMS method by Jull et al. (1984,1989b, 1998) are youngest, and our results of the AMS method are intermediate. The difference would be caused by analytical uncertainties, contamination in samples, incomplete fusion of samples and back-ground value in the extraction system. Y-74190,Y-75097 and Y-75108,which are thought to have fallen at the same time as Y-75102,gave similar ages of 〜4 ka, though Y-74190 gave a slightly younger age of 2.8 ka. These four chondrites might have fallen at the same time. Further studies are needed to improve analytical technique : reducing back-ground value of the extraction system and complete combustion of meteorites by such as longer heating time in RF furnace and use of much more combustion accelerator. It is indispensable to measure saturated ^<14>C activity of recently fallen meteorites with our extraction system. Furthermore, shielding or depth corrections are needed for ^<14>C terrestrial age determination of a meteorite sample if the meteoroid was very large or very small. We intend to obtan the other radioisotope data such as ^<10>Be to estimate the shielding effect. By normalizing the saturated activity of ^<14>C to that of ^<10>Be in a meteorite, more correct terrestrial age for the meteorite could be obtained.

DOI： 10.18999/sumrua.12.134

Publisher：Nagoya University  

A Tandetron accelerator mass spectrometer, an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Center for Chronological Research (CCR), Nagoya University. A so-called second generation AMS ^<14>C apparatus manufactured by High Voltage Engineering Europe, BV, the Netherlands has been installed at CCR in 1997 and has been tested of its performance on ^<14>C measurements. The authors present here a brief review of the present performance and status of the Tandetron-I and Tandetron-II AMS systems. The ^<14>C measurement error (one sigma error) of the Tandetron-II is around +/-20-+/-40 years, which is clearly smaller than that of the Tandetron-I (around+/-50-+/-90 years). In addition, the reproducibility tests of ^<14>C measurements for the IAEA C1-C8 ^<14>C standards suggests that accuracy of ^<14>C measurement can be as good as around 0.5%.

DOI： 10.18999/sumrua.12.35

Publisher：Nagoya University  

A new gamma-ray counting and data processing system for non-destructive neutron activation analysis has been set up in Radioisotope Center in Nagoya University. The system carry out gamma-ray counting, sample change and data processing automatically, and is able to keep us away from parts of complicated operations in INAA. In this study, we have arranged simple analytical procedure that makes practical works easier than previous. The concrete flow is described from the preparation of powder rock samples to gamma-ray counting and data processing by the new INAA system. Then it is run over that the analyses used two Geological Survey of Japan rock reference samples JB-1a and JG-1a in order to evaluate how the new analytical procedure give any speediness and accuracy for analyses of geological materials. Two United States Geological Survey reference samples BCR-1 and G-2 used as the standard respectively. Twenty two elements for JB-1a and 25 elements for JG-1a were analyzed, the uncertainty are <5% for Na, Sc, Fe, Co, La, Ce, Sm, Eu, Yb, Lu, Hf, Ta and Th, and of <10% for Cr, Zn, Cs, Ba, Nd, Tb and U. This system will enable us to analyze more than 1500 geologic samples per year.

DOI： 10.18999/bulnum.017.03

Publisher：Nagoya University  

Diurnal variations of carbon isotopic compositions (Δ^<14>C and δ^<13>C) of atmospheric CO_2 as well as concentration in an urban area on 9 February, 1999 were measured. The carbon isotopic approach in the present study discriminated quantitative contributions from the several CO_2 sources, i.e., background, anthropogenic and biogenic components, in the urban atmosphere. The diurnal variations in vertical profiles in anthropogenic and biogenic components within the forest were estimated, and their contributions were ranged from 1.3 to 15.8% and from 1.6 to 7.8%, respectively. There was a little variation vertically at each time in the respective components, whereas anthropogenic CO_2 fluctuated largely according to the total atmospheric CO_2 variation. On the other hand, the biogenic CO_2 concentration remained relatively constant throughout the day. With regard to the vertical profiles, the biogenic contribution increases from the top to the floor of the forest with smooth gradient, while the anthropogenic contribution shows the mirror image profile against biogenic one. Both of them showed the large gradual change especially during the night.

DOI： 10.18999/sumrua.11.88

Publisher：Nagoya University  

A Tandetron accelerator mass spectrometer, an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Dating and Materials Research Center, Nagoya University. The authors present here a brief review of the present performance and some archaeological and geological applications of the Tandetron-I AMS, as well as a brief introduction to application field of ^<10>Be measurements. After the second AMS machine goes into routine operation, the main purpose of the Tandetron-I AMS will be shifted towards ^<10>Be measurements. Some hardware and software tools are in preparation now for the ^<10>Be measurements.

DOI： 10.18999/sumrua.11.38

Publisher：Nagoya University  

Terrestrial age of meteorites gives us important information to estimate the terrestrial history of the meteorites. With the advent of AMS, the required sample mass of meteorite for measurement has been reduced as small as 0.1g. As a result, many more ^<14>C measurements have been performed intensively by the Toronto AMS group, Canada, the Arizona AMS group, USA, and so on. In Japan, AMS ^<14>C measurements of meteorites have been scarcely performed, to our regret. We are now at the early stage of the program for studying ^<14>C activities in meteorites, and constructing a system to extract ^<14>C from meteorites, in a similar method used by the Arizona group. A meteorite powder sample mixed with pure iron chips is combusted in a RF furnace (Leco HF-10) in the presence of purified carbon-free oxygen in a closed vacuum-tight glass line system. The sample gases evolved are passed through MnO_2 and Pt/CuO traps, and then the CO_2 is separated in a liq.N_2 trap, by pumping out oxygen completely. The amount of ^<14>CO_2 is determined by a pressure transducer in a certain volume and diluted with a known amount of ^<14>C^free CO_2. The total CO_2 is graphitized by reducing with hydrogen in a Fe-powder catalyst and the produced graphite is measured of its ^<14>C concentration with a Tandetron accelerator mass spectrometer at the Dating and Materials Research Center, Nagoya University. Extraction yields of CO_2 using the above method which employs RF melting of steel standards of known carbon content were about 90%. The new extraction procedure gave higher extraction yields and older ^<14>C ages than those using the old extraction method. Carbon yields of two Antarctic meteorites (Y-75102 and ALH-77294), however, were significantly low, and the carbon-14 terrestrial ages for the meteorites were different from the reported values. The results might be caused by imperfect combustions of the meteorites and high blanks from the crucible with iron chips alone. Further studies are needed to improve analytical techniques.

DOI： 10.18999/sumrua.11.100

Publisher：Nagoya University  

XAD-2 rasin is considered a good material to separate quantiatively polar amino acids from less polar fulvic and humic acids, which are predominant sources of error in ^<14>C and stable isotope analysis on collagen of fossil bone. To evaluate if XAD-2 treatment affects carbon and nitrogen isotope values, Minami (1999) measured δ^<13>C and δ^<15>N on several extracted fractions of collagens from modern bovine Achilles heel tendons made of Sigma Chemical and Nacalai Tesque. There were about +1.0‰ difference in δ^<13>C and about -0.1‰ in δ^<15>N between hydrolyzed collagen and XAD-treated collagen hydrolysates from modern collagen standards. On the other hand, the carbon and nitrogen isotope fractionations were about -0.6‰ and +0.3‰ in δ^<15>N, respectively, on animal fossil bones collected from collected from the Awazu submarine archeological site in this study. The C/N ratios, δ^<13>C and δ^<15>N values of extracted fractions : decalcified, hydrolyzed and XAD-treated hydrolysate fractions, vary as chemical extraction proceeded. The change of the isotope values, which differ between fossils and modern collagens, might be caused by purification of collagen, decomposition of a part of collagen, and combined changes in amino acid composition in collagen. The XAD-treatment affected amino acid compositions on both fossils and modern collagen standards. Since there was no difference in both δ^<13>C and δ^<15>N values by XAD-2 treatment on amino acid standards (Minami, 1999), the isotope fractionation with XAD-2 resin on the collagens can not be due to the total isotope variation of individual amino acids, but be due to the change of amino acid compositions. We need to further study the effect of chemical treatment with HCl on carbon and nitrogen isotope ratios of collagen with XAD-2 resin.

DOI： 10.18999/sumrua.11.231

Publisher：Nagoya University  

DOI： 10.18999/sumrua.10.235

Publisher：Nagoya University  

The predominant contaminants such as humic and fulvic acids affect ^<14>C date and stable isotope analyses in fossil bone. The XAD-2 treatment of collagen hydrolysate is considered an effective method to eliminate the foreign organic matter from bone. In this study, we have conducted ^<14>C dating, by the XAD-2 method, on a molar fossil of Naumann's elephant (Palaeoloxodon naumanni) collected from the Uwa-sea, offshore Natori-kajitanihana, Nishi-Uwa-gun, Ehime prefecture. The ^<14>C date of 29,200±870 yr BP was already obtained for gelatin collagen by gelatin-extraction method of decalcification in a cellulose tube with 1.2N HCl, followed by heating at 90℃ in water (Nakamura et al., 1998). Three parts of dentine, enamel and cement in the molar fossil were separated for each ^<14>C dating. The samples were decalcificated with 4℃, 0.8N HCl and the acid-insoluble residues were concentrated by centrifugation and lyophilized. The demineralized fractions were hydrolysed with 6N HCl at 110℃. The filtered hydrolysates were passed through the XAD-2 resin to remove fulvic and humic acids. Dentine phase in the molar fossil gives older ^<14>C age than enamel and cement phases. It is thought that the dentine, covered with enamel and cement phases, is better-preserved. The ^<14>C age of the XAD-purified hydrolysates (XAD) is older than that of solution collagen (SC), but coincide with age of gelatin collagen (GC) in dentine phase. Enamel phase gives different C/N ratio, δ ^<13>C and δ ^<15>N values from those of dentine and cement phases, and relatively younger age, which indicates that the majority of enamel protein has decomposed and changed to hydroxyapatite. All fulvic fractions (F) of three phases give significantly younger ages than bone organic carbon. The molar fossil might be well-preserved because of the higher yield (1.22%) of gelatin collagen more than 1%. The gelatin-extraction method is sufficient for ^<14>C dating on the well-preserved fossil.

DOI： 10.18999/sumrua.10.139

Publisher：Nagoya University  

A Tandetron accelerator mass spectrometer, an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Dating and Materials Research Center, Nagoya University. The authors present here a brief review of the present performance and some archaeological and geological applications of the Tandetron-I AMS, as well as a brief introduction to a so-called second generation AMS machine, an AMS ^<14>C dating apparatus, currently of the highest performance, manufactured by High Voltage Engineering Europe, BV, the Netherlands, which has been recently installed at the Dating and Materials Research Center. Results of the recent performance tests of the Tandetron-II AMS machine are briefly described.

DOI： 10.18999/sumrua.10.5

Publisher：Nagoya University  

DOI： 10.18999/sumrua.10.189

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：Nagoya University  

A Tandetrno accelerator mass spectrometer (AMS), an apparatus dedicated to radiocarbon (^<14>C) measurements with high sensitivity, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure ^<14gt;C concentrations of environmental samples as well as ^<14>C dates of geological and archeological materials at the Dating and Materials Research Center (DMRC), Nagoya University. No serious problem has occurred with the machine, which resulted in that 770 samples were measured in 1997,and totally 7,371 samples in various fields have been measured since the installation of the machine. Though the Tandetron AMS has been operated intensively, the number of samples analyzed annually is rather limited to several hundreds which is far smaller than the number of samples brought to the DMRC by many users from various research fields, mainly owing to lower negative current intensity from an ion source (HICONEX-844,modified for loading 18 targets at a time), as well as a rather low throughput of the total system. We could have fortunately introduced a new-generation Tandetron which is manufactured by High Voltage Engineering Europe (HVEE) BV, the Netherlands. Two sets of similar HVEE AMS system have been installed successfully at the University of Groningen, Holland, and at the University of Christian-Albrechts, Kiel, Germany. They have already shown excellent performances in carbon-isotope-ratio measurments : reproducibility of ^<12>C/^<13>C ratio as ±0.1%; error and reproducibility of ^<14>C/^<12>C ratio as ±0.15%-±0.22% and ±0.3%, respectively. We are planning to perform high accuracy and high precision ^<14>C dating of mainly cultural property materials of historical age, archeological and geological samples, by using the new-generation machine.

DOI： 10.18999/10.19999/sumrua.9.126

Publisher：Nagoya University  

We have conducted ^<14>C dating, with a Tandetron accelerator mass spectrometer (AMS) at Nagoya University, on carbon from collagen fractions extracted from a molar tooth fossil of Naumann's elephant (Palaeoloxodon naumanni) collected from the Uwa-sea, offshore Natori-Kajitanihana, Nishi-Uwa-gun, Ehime prefecture. The molar fossil was cleaned on the surface with a steel brush and a dental grinder, treated with 0.5M NaOH solution, and ground into powder. Two sets of the powdered sample, about 3.8g and 4.9g each, were demineralized with 1.2N HCl in a cellulose tube to extract collagen. After demineralization, HCl was completely removed from the tube by dialysis. Then the solution fraction in the tube was separated by centrifuge, and freeze-dried to get a solution-collagen fraction. Solid remains were put in a Pyrex tube with 20ml of distilled water and heated at 90℃ for 10 hours to extract the water soluble gelatin-collagen fraction. Collagen was oxidized, using CuO to produce CO_2,in a Vycor tube at 950℃ for an hour. A small aliquot of the CO_2 was analyzed for its' stable carbon isotope ratio, δ ^<13>C_<PDB>, using a triple-collector mass spectrometer (MAT-252). To produce graphite, the remaining CO_2 was reduced by hydrogen, with an Fe-powder catalyst, in a Vycor tube at 650℃ for several hours. The sample graphite was analyzed for its' ^<14>C/^<13>C ratio, relative to that of an oxalic acid standard (NBS-SRM-4990). In general, reliable ^<14>C dates can be obtained for collagen fractions extracted from the fossil sample, provided that the collagen fractions have been preserved well from weathering in nature. Experimental yields of collagen fractions were relatively high, ranging from 1.22 to 1.51%. The CO_2 yield from the gelatin collagen fraction was 42%, being consistent with the values of 41-42% for gelatin collagen extracted from fresh bone samples. On the other hand, the CO_2 yield from the solution fraction was 25%, being lower than the values of 41-42%. Thus the ^<14>C date of 29,200±870 yr BP, obtained for the gelatin collagen fraction, seems to be reliable and can be assigned as the age of the molar fossil sample, though the ^<14>C date is about 4,000 years older than the value of 24,880±580 yr BP obtained for the solution collagen fraction. The δ ^<13>C_<PDB> values of -20.2‰ for the both gelatin and solution collagen fractions were consistent with accepted δ ^<13>C_<PDB> values, of from -21 to -23‰ for herbivorous mammals.

DOI： 10.18999/10.19999/sumrua.9.286

Publisher：Nagoya University  

This paper provides a basic experimental information of stable nitrogen isotopic measurements with MAT-252 mass spectrometer (Finnigan MAT Ltd.) at Dating and Materials Research Center, Nagoya University, and a refining method of N_2 gas from sample gas on vacuum line. The ion output voltage from 28 collector is directly proportional to N_2 gas pressure. In case that ion output voltage from 28 collector of N_2 gas is more than 1.6V, the ratio of [29]/[28] hardly varies according to the output voltage, and the pressure effect on nitrogen isotopic ratios can be disregarded. The 28 ion output voltage of 2.5V (N_2 gas pressure around 38mb) is recommended on normal measurements. Only N_2 gas can be separated and refined from a sample gas by means of molecular sieves on vacuum line for refining CO_2. The δ^<13>C values do not change by collecting N_2.

DOI： 10.18999/10.19999/sumrua.9.316

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Publisher：Nagoya University  

A Tandetron accelerator mass spectrometer (AMS), an apparatus dedicated to radiocarbon (^<14>C) measurements with high sensitivity, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archeological materials at the Dating and Materials Research Center (DMRC), Nagoya University. No serious problem has occurred with the machine, which resulted in that 708 samples were measured in 1996,and totally 6,300 samples in various fields have been measured since the installation of the machine. Though the Tandetron AMS has been operated intensively, the number of samples analyzed annually is rather limited to several hundreds which is far smaller than the number of samples brought to the DMRC by many users from various research fields, mainly owing to lower negative current intensity from an ion source (HICONEX-844,modified for loading 18 targets at a time), as well as a rather low throughput of the total system. We could have fortunately introduced a new-generation Tandetron which is manufactured by High Voltage Engineering Europe (HVEE) BV, the Netherlands. Two sets of similar HVEE AMS system have been installed successfully at University of Groningen, Holland, and at University of Christian-Albrechts, Kiel, Germany. They have already shown excellent performances in carbon-isotope-ratio measurements : reproducibility of ^<12>C/^<13>C ratio as ア0.1% ; error and reproducibility of ^<14>C/^<12>C ratio as ア0.15-0.22% and ア0.3%, respectively. We are planning to perform high accuracy and high precision ^<14>C dating of mainly cultural property materials of historical age, archeological and geological samples, by using the new-generation machine.

DOI： 10.18999/sumrua.8.56

Publisher：Nagoya University  

The Awazu submarine archeological site, 2-3 meters below the water surface, is located at southern basin of Lake Biwa, near the mouth of Seta River flowing out of the Lake Biwa. A shell mound was excavated during the 1990-1991 year survey of the site. Seven sets of wood, mammalian bone, and shell fossil samples collected from the same layers of the shell mound were dated with the AMS radiocarbon method. The ^<14>C dates for each of the three kinds of samples did not show big difference between the seven layers. This tendency is consistent with the fact that the shell mound was formed within ca. 100 years, because pottery fragments of the Funamoto-I type, which corresponds to early stage of the middle Jomon, were preferentially discovered from this shell mound. However, ^<14>C dates were systematically different among three types of samples : shell fossil samples showed the oldest dates from 4800-5080yr BP, except for a very young date (4630+/-80yrBP); wood samples did the middle ones (4570-4760yrBP); and bone fragment samples did the youngest ones (4090-4430yrBP). The reasons for the difference of ^<14>C dates among the three kinds of samples collected from the same horizons are not clarified yet. Shell carbonate originates from dissolved inorganic carbon in the lake water, which carbon was produced partly in the dissociation of old organic materials in the lake sediment and was also added with dead carbon from limestone rock surrounding Lake Biwa. In addition, younger carbon contaminated the bone samples when the samples were in the sediment may not have been removed completely during chemical preparation procedures of the samples.

DOI： 10.18999/sumrua.8.237