Faculty Profiles - MINAMI, Masayo

Papers - MINAMI, Masayo

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Sr-87/Sr-86 age determination by rapidly formed spherical carbonate concretions (9, 1003, 2019) Reviewed

Yoshida Hidekazu, Asahara Yoshihiro, Yamamoto Koshi, Katsuta Nagayoshi, Minami Masayo, Metcalfe Richard

SCIENTIFIC REPORTS Vol. 9 ( 1 ) page： 7184 2019.5

高崎の烏川に産する巨石「聖石」の起源 Reviewed

佐藤興平・南雅代・武者巌・柴田賢

群馬県立自然史博物館研究報告 Vol. 23 page： 49 - 56 2019.3

火山泥流に含まれる木片の14C不一致年代：前橋泥流と塚原泥流の例

南雅代, 中村俊夫

群馬県立自然史博物館研究報告 Vol. 23 page： 57 - 64 2019.3

Landscape and early farming at Neolithic sites in Slemani, Iraqi Kurdistan: A case study of Jarmo and Qalat Said Ahmadan. Reviewed International coauthorship

Tsuneki, A., Rasheed, K., Watanabe, N., Anma, R., Tatsumi, Y., Minami, M.

Paleorient Vol. 45 ( 2 ) page： 33-52 2019

西アジアの古環境復元に向けてーイラン北西部のザグロス山脈に分布する石灰質化学沈殿岩の現地調査報告

南雅代

新学術領域研究(研究領域提案型)「都市文明の本質：古代西アジアにおける都市の発生と変容の学際研究」研究成果報告2018年度 Vol. - page： 143 - 148 2019

Fe-oxide concretions formed by interacting carbonate and acidic waters on Earth and Mars

Yoshida H, Hasegawa H, Katsuta N, Maruyama I, Sirono S, Minami M, Asahara Y, Nishimoto S, Yamaguchi Y, Ichinnorov N, Metcalfe R

SCIENCE ADVANCES Vol. 4 ( 12 ) 2018.12

Sr-87/Sr-86 compositional linkage between geological and biological materials: A case study from the Toyota granite region of Japan

Minami M, Suzuki K

CHEMICAL GEOLOGY Vol. 484 page： 224 - 232 2018.5

Pseudo-fixed dead time circuit for designing and implementation of JEOL-type X-ray counting system

Kato Takenori, Suzuki Kazuhiro, Jeen Mi-Jung, Minami Masayo

Chemical Geology Vol. 484 page： 16 - 21 2018.5

Generalized conditions of spherical carbonate concretion formation around decaying organic matter in early diagenesis Reviewed

Yoshida,H, Yamamoto,K, Minami,M, Katsuta,N, Sirono,S, Metcalfe,R

Scientific Reports Vol. 8 ( 1 ) page： 6308 2018.4

Bomb-C-14 Peak in the North Pacific Recorded in Long-Lived Bivalve Shells (Mercenaria stimpsoni) Reviewed

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

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS Vol. 123 ( 4 ) page： 2867 - 2881 2018.4

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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Scopus

関東山地北西縁下仁田地域に産する珪長質火成岩体のU-Pbジルコン年代 Reviewed

佐藤興平・竹内誠・鈴木和博・南雅代・柴田賢

群馬県立自然史博物館研究報告 Vol. 22 page： 79 - 94 2018.3

木片の14C年代測定による前橋泥流堆積時期の再検討（予察） Reviewed

南雅代, 中村俊夫

群馬県立自然史博物館研究報告 Vol. 22 page： 95 - 101 2018

Formation of gigantic spherical carbonate concretion in early diagenesis

Muramiya Yusuke, Yoshida Hidekazu, Yamamoto Koshi, Minami Masayo

The Journal of the Geological Society of Japan Vol. 123 ( 11 ) page： 939 - 952 2017.11

Language：Japanese Publisher：The Geological Society of Japan

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.

DOI： 10.5575/geosoc.2017.0039

CiNii Research

J-GLOBAL

Comparing the Sr-87/Sr-86 of the bulk and exchangeable fractions in stream sediments: Implications for Sr-87/Sr-86 mapping in provenance studies Reviewed

Yuka Jomori, Masayo Minami, Akiko Sakurai-Goto, Atsuyuki Ohta

APPLIED GEOCHEMISTRY Vol. 86 page： 70 - 83 2017.11

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 < 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 < 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 < 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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Grain-size variations in 87Sr/86Sr and elemental concentrations of stream sediments in a granitic area: Fundamental study on 87Sr/86Sr spatial distribution mapping

Minami Masayo, Jomori Yuka, Suzuki Kazuhiro, Ohta Atsuyuki

GEOCHEMICAL JOURNAL Vol. 51 ( 6 ) page： 469 - 484 2017

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

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.

DOI： 10.2343/geochemj.2.0478

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Scopus

CiNii Research

A distinctive chemical composition of the tektites from Thailand and Vietnam, and its geochemical significance Reviewed

Lee, S-G., Tanaka, T., Asahara, Y., Minami, M.

Jour. Petrol. Soc. Korea Vol. 26 page： 281-295 2017

14C Ages and the Significance of Porites, Beached on the Eastern Part of Maibah Beach, Southeast of Miyako Island, Okinawa Prefecture

OMOTO Kunio, MINAMI Masayo

Quarterly Journal of Geography Vol. 69 ( 3 ) page： 119 - 127 2017

Language：Japanese Publisher：The Tohoku Geographical Association

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 Tridacna gigas. 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 Tridacna gigas. The samples indicated obviously a characteristic of coralline structure. Then identification and radiocarbon dating of the samples were performed.The results show that coral is Porites sp. and probably in situ, 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 Porites 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 Porites 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 Porites （1653±23 cal AD） coincides with AD 1667 earthquake tsunami with a margin of statistical error. However, age of removed soft outer layers of Porites 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.

DOI： 10.5190/tga.69.3_119

CiNii Research

炭化物の高確度14C年代測定のための試料調製法の検討

南雅代, 中村俊夫

第19回AMSシンポジウム・2016年度「樹木年輪」研究会報告集 Vol. 1 page： 82 - 85 2017

A distinctive chemical composition of the tektites from Thailand and Vietnam, and its geochemical significance. Reviewed International coauthorship

南雅代

Jour. Petrol. Soc. Korea Vol. 26 page： 281 - 295 2017

CHANGES OF CHEMICAL STRUCTURE AND COMPOSITION OF CHARCOAL BY RADIOCARBON PRETREATMENTS: DECONTAMINATION BY ABA AND ABOx TREATMENTS Reviewed

Shinji Tomiyama, Masayo Minami, Toshio Nakamura, Koichi Mimura, Hiroyuki Kagi

RADIOCARBON Vol. 58 ( 3 ) page： 565 - 581 2016.9

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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Papers - MINAMI, Masayo