Faculty Profiles - MINAMI, Masayo

Papers - MINAMI, Masayo

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Salinity, oxygen isotope, hydrogen isotope, and radiocarbon of coastal seawater of North Japan Reviewed

Kubota, K., Sakai, K., Ohkushi, K., Higuchi, T., Shirai, K., Minami, M

Geochemical Journal Vol. 56 page： 240 - 249 2022.12

14C dating of Holocene carbonate concretions collected in Nagoya Port area, central Japan

Minami Masayo, Kuma Ryusei, Asai Saki, Takahashi Hiroshi A., Yoshida Hidekazu

The Journal of the Geological Society of Japan Vol. 128 ( 1 ) page： 239 - 244 2022.11

Language：Japanese Publisher：The Geological Society of Japan

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.

DOI： 10.5575/geosoc.2022.0021

CiNii Research

Assessment of the influence of benzalkonium chloride addition on radiocarbon analysis of dissolved inorganic carbon

Takahashi, HA; Minami, M

LIMNOLOGY AND OCEANOGRAPHY-METHODS Vol. 20 ( 10 ) page： 605 - 617 2022.10

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

Web of Science

Scopus

S-type like granites and felsic volcanic rocks in the Mahabad area, NW Iran: Late Neoproterozoic extensional tectonics follow collision on the northern boundary of Gondwana

Gholipour, S; Azizi, H; Masoudi, F; Asahara, Y; Minami, M

LITHOS Vol. 416 2022.5

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

Web of Science

Scopus

Glendonite concretion formation due to dead organism decomposition

Yusuke Muramiya, Hidekazu Yoshida, Masayo Minami, Tomoyuki Mikami, Toshinori Kobayashi, Kousuke Sekiuchi, Nagayoshi Katsuta

Sedimentary Geology Vol. 429 page： 106075 - 106075 2022.3

浅間火山初期の山体で発生した山体崩壊の年代：塚原泥流に含まれる樹木片の14C年代からの推定 Reviewed

佐藤興平・南雅代・安部久・池田信二

群馬県立自然史博物館研究報告書 2022.3

前橋泥流の流下域に残存する安山岩塊の比重とSr同位体比 Reviewed

佐藤興平・南雅代・武者巌

群馬県立自然史博物館研究報告書 Vol. 26 page： 91 - 104 2022.3

関東山地下仁田地域北部に分布する中生界のジルコンU−Pb年代 Reviewed

河合航汰・竹内　誠・志村侑亮・佐藤興平・南　雅代

群馬県立自然史博物館研究報告書 Vol. 26 2022.3

加速器質量分析法による日本刀や古い鉄器類の放射性炭素年代測定.

中村俊夫, 山田哲也, 齋藤努, 南雅代

年代測定研究 Vol. 6 page： 27 - 34 2022

Salinity, oxygen isotope, hydrogen isotope, and radiocarbon of coastal seawater of North Japan

Kubota Kaoru, Sakai Keisuke, Ohkushi Ken’ichi, Higuchi Tomihiko, Shirai Kotaro, Minami Masayo

GEOCHEMICAL JOURNAL Vol. 56 ( 6 ) page： 240 - 249 2022

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

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.

DOI： 10.2343/geochemj.GJ22021

Web of Science

Scopus

CiNii Research

Hadal aragonite records venting of stagnant paleoseawater in the hydrated forearc mantle

Oyanagi Ryosuke, Okamoto Atsushi, Satish-Kumar Madhusoodhan, Minami Masayo, Harigane Yumiko, Michibayashi Katsuyoshi

COMMUNICATIONS EARTH & ENVIRONMENT Vol. 2 ( 1 ) 2021.12

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

Web of Science

Scopus

Coexistence of two types of Late Paleocene adakitic granitoid, Soursat complex, NW Iran

Nouri Fatemeh, Azizi Hossein, Asahara Yoshihiro, Whattam Scott A., Tsuboi Motohiro, Mohammad Yousif Osman, Minami Masayo, Anma Ryo

LITHOS Vol. 404 2021.12

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

Web of Science

Scopus

EVIDENCE OF MASS MORTALITY OF THE LONG-LIVED BIVALVE MERCENARIA STIMPSONI CAUSED BY A CATASTROPHIC TSUNAMI

Kubota Kaoru, Shirai Kotaro, Murakami-Sugihara Naoko, Seike Koji, Minami Masayo, Nakamura Toshio, Tanabe Kazushige

RADIOCARBON Vol. 63 ( 6 ) page： 1629 - 1644 2021.12

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

Web of Science

Scopus

A SIMPLE CO2 EXTRACTION METHOD FOR RADIOCARBON ANALYSES OF DISSOLVED INORGANIC CARBON IN WATER SAMPLES WITHOUT A CARRIER GAS

Takahashi Hiroshi A., Handa Hiroko, Minami Masayo

RADIOCARBON Vol. 63 ( 4 ) page： 1339 - 1353 2021.8

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

Web of Science

Scopus

Geochemistry and Genesis of Beryl Crystals in the LCT Pegmatite Type, Ebrahim-Attar Mountain, Western Iran

Daneshvar Narges, Azizi Hossein, Asahara Yoshihiro, Tsuboi Motohiro, Minami Masayo, Mohammad Yousif O.

MINERALS Vol. 11 ( 7 ) 2021.7

Early Miocene post-collision andesite in the Takab area, northwest Iran Reviewed International coauthorship

Hossein Azizi, Narges Daneshvar, Asrin Mohammadi, Yoshihiro Asahara, Scott A Whattam, Motohiro Tsuboi, Masayo Minami

Journal of Petrology 2021.3

前橋の敷島公園に産する巨石「お艶ヶ岩」の起源 Reviewed

佐藤興平・南　雅代・池田信二・安倍　久・小島純一・武者　巌

群馬県立自然史博物館研究報告書 Vol. 25 page： 65 - 74 2021.3

高崎市のボーリングコアから見出された木片の14C年代と高崎ー前橋地域の後期更新世の地層形成史における意義 Reviewed

群馬県立自然史博物館研究報告書 Vol. 25 page： 81 - 90 2021.3

吾妻川上流域の火山泥流堆積物に含まれる木片の14C年代（予察） Invited Reviewed

佐藤興平・南　雅代・安部　久・中村俊夫・中村庄八・黒岩利明・嶋村　明・武者　巌

群馬県立自然史博物館研究報告書 Vol. 25 page： 91 - 100 2021.3

利根川河床の前橋泥流から見出された木片群の14C年代 Invited Reviewed

佐藤興平・南　雅代・安倍　久・中村俊夫・武者　巌

群馬県立自然史博物館研究報告書 Vol. 25 page： 78 - 80 2021.3

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Papers - MINAMI, Masayo