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Redox history of the Three Gorges region during the Ediacaran and Early Cambrian as indicated by the Fe isotope

Geoscience Frontiers 2018年第1期9卷 155-172页

作者： Yusuke Sawaki miyuki tahata Tsuyoshi Komiya Takafumi Hirata Jian Han Degan Shu Department of Earth and Planetary Sciences Tokyo Institute of Technology Department of Earth Science and Astronomy Graduate School of Arts and Sciences The University of Tokyo Geochemistry Research Center The University of Tokyo Department of Geology and Key Laboratory for Continental Dynamics Northwest University

The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life.Even though ancient redox conditions can be inferred from the composition of sedimentary iron mineral species,this method is not necessarily applicable to all rocks.In the Earth system,the cycling of iron is of considerable interest owing to its sensitivity to redox conditions.Information regarding the paleo-oceanic iron cycle is revealed in the iron isotopic composition of ironbearing minerals.Unfortunately,only limited iron isotopic data exists for Ediacaran-to Cambrianperiod oceans.To circumvent this deficiency,we drilled a fossiliferous Ediacaran to Early Cambrian sedimentary succession in the Three Gorges region,South China.We analyzed the iron isotope ratios(δ^(56/54)Fe)of pyrite grains in the drill cores using laser ablation multi collector inductively coupled plasma mass spectrometry.The results demonstrate large variations inδ^(56/54)Fe,from-1.6 to 1.6‰,and positive iron isotope ratios are observed in many successions.The presence of positiveδ^(56/54)Fe in pyrite indicates that the ferrous iron in the seawater was partially oxidized,suggesting that seawater at Three Gorges was ferruginous during the Ediacaran and Early Cambrian periods.However,aggregated pyrite grains in organic carbon-rich black shales at Member 4 of the Doushantuo Formation and the base of the Shuijingtuo Formation yield near-zeroδ^(56/54)Fe values;this suggests that the ocean was transiently dominated by sulfidic conditions during these periods.Notably negativeδ^(56/54)Fe values,lower than-1‰,can be interpreted as a signature of DIR.The DIR also might contribute in part to the re-mineralization of organic matter during the largest negative carbon isotope anomaly in the Ediacaran.

关键词： δ56/54Fe Pyrite Ediacaran Cambrian Three Gorges

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Three-step modernization of the ocean:Modeling of carbon cycles and the revolution of ecological systems in the Ediacaran/Cambrian periods

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Geoscience Frontiers 2015年第1期6卷 121-136页

作者： miyuki tahata Yusuke Sawaki Yuichiro Ueno Manabu Nishizawa Naohiro Yoshida Toshikazu Ebisuzaki Tsuyoshi Komiya Shigenori Maruyama Department of Earth and Planetary Sciences Tokyo Institute of Technology Earth-Life Science Institute Tokyo Institute of Technology Precambrian Ecosystem Laboratory Japan Agency for Marine-Earth Science and Technology(JAMSTEC) Department of Environmental Science and Technology Tokyo Institute of Technology RIKEN 2-1 Hirosawa Department of Earth Science and Astronomy The University of Tokyo Research Center for the Evolving Earth and Planets Tokyo Institute of Technology

Important ecological changes of the Earth （oxidization of the atmosphere and the ocean） increase in nutrient supply due to the break-up of the super continent （Rodinia） and the appearance of multi-cellular organisms （macroscopic algae and metazoan） took place in the Ediacaran period, priming the Cambrian explosion. The strong perturbations in carbon cycles in the ocean are recorded as excursions in carbonate and organic carbon isotope ratio （δ13Ccarb and δ13Corg） from the Ediacaran through early Cambrian periods. The Ediacaran-early Cambrian sediment records of δ13Ccarb and δ13Corg, obtained from the drill-core samples in Three Gorges in South China, are compared with the results of numerical simulation of a sim- ple one-zone model of the carbon cycle of the ocean, which has two reservoirs （i.e., dissolved organic carbon （DOC） and dissolved inorganic carbon （DIC）. The fluxes from the reservoirs are assumed to be proportional to the mass of the carbon reservoirs. We constructed a model, referred to here as the Best Fit Model （BFM）, which reproduce δ13Ccarb and δ13Corg records in the Ediacaran-early Cambrian period noted above. BFM reveals that the Shuram excursion is related to three major changes in the carbon cycle or the global ecological system of the Earth：（1） an increase in the coefficient of remineralization by a factor of ca. 100, possibly corresponding to a change in the dominant metabolism from anaerobic respiration to aerobic respiration, （2） an increase of carbon fractionation index from 25‰, to 33‰, possibly corresponding to the change in the primary producer from rock-living cyanobacteria to free-living macro algae, and （3） an in- crease in the coefficient of the organic carbon burial by a factor of ca. 100, possibly corresponding to the onset of a biological pump driven by the flourishing metazoan and zooplankton. The former two changes took place at the start of the Shuram excursion, while the third occurred at the end of the Shuram excursion. The other two excursions are explained by the tentativ

关键词： Carbon cycle change Carbon isotope ratio Ediacaran to Cambrian Oxygen level Evolution of life

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A high-resolution chemostratigraphy of post-Marinoan Cap Carbonate using drill core samples in the Three Gorges area, South China

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Geoscience Frontiers 2016年第4期7卷 663-671页

作者： Hisatoshi Sato miyuki tahata Yusuke Sawaki Shigenori Maruyama Naohiro Yoshida Degan Shu Jian Han Yong Li Tsuyoshi Komiya Department of Earth and Planetary Sciences Tokyo Institute of Technology Department of Environmental Science and Technology Tokyo Institute of Technology Department of Environmental Chemistry and Engineering Tokyo Institute of Technology Department of Geology and Key Laboratory for Continental Dynamics Northwest University School of Earth Sciences and Resources Management Chang’an University Department of Earth Science and Astronomy The University of Tokyo

Cap Carbonates overlie the Marinoan Snowball Earth-related glacial diamictite, and possibly record the drastic surface environmental change and biological evolution after the Snowball Earth. We conducted on-land drilling from the Liantuo Formation, through the Nantuo, to the lower Doushantuo Formation in the Three Gorges area of South China to collect fresh, continuous samples in the Three Gorges area. We obtained high-resolution chemostratigraphies of ~13C and 6180 values of carbonates from the topmost part of the Nantuo Formation to the Cap Carbonate, in order to decode the detailed surface environmental change in the shallow marine setting. The δ3C chemostratigraphy possesses some unique characteristics：（1） stable δ13C values as a whole, but ubiquitous low δ13C anomalies through the Cap Carbonate, （2） increase of the δ13C values from -3 to ＋5‰ across the C2/C3 boundary, （3） no δ13C anomaly between the CI and C2 boundary, and （4） presence of an anomalous high δ13C value （＋2.3%0） and a faint positive correlation between δ13C and δ18O values in the C1 unit. Evidence of quite low δ13C anomalies （with a nadir of -41‰）, ubiquitous negative δ13C anomalies through the Cap Carbonate, and a high 613C anomaly accompanied with a faint positive correlation between δ13C and δ18O values in the C1 unit supports decomposition and formation of methane hydrate during Cap Carbonate formation. The drastic increase of δ13C values from the upper C2 to C3 units in- dicates enhancement of primary productivity and organic carbon burial, possibly due to high continental fluxes after the Snowball Earth event, evidenced by high Sr isotope values. The increase is restricted to the proximal side of the inner shelf in South China, and the timing of the increase of δ13C values of carbonates is earlier at Three Gorges area than any other area, suggesting that the enhancement of primary productivity started in the proximal environment because of higher continental influxes. The increase in oxygen contents of seawater due to the enhanced prima

关键词： Cap Carbonate Ediacaran Marinoan Snowball Earth Carbon isotope chemostratigraphy Methane hydrate

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Decomposition of Point-Symmetry Using Ordinal Quasi Point-Symmetry for Ordinal Multi-Way Tables

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Open Journal of Statistics 2016年第3期6卷 381-386页

作者： Yusuke Saigusa Kouji tahata Sadao Tomizawa Department of Information Sciences Tokyo University of Science Chiba Japan

For multi-way tables with ordered categories, the present paper gives a decomposition of the point-symmetry model into the ordinal quasi point-symmetry and equality of point-symmetric marginal moments. The ordinal qua... 详细信息

关键词： Decomposition Multi-Way Table Ordinal Quasi Point-Symmetry Point-Symmetry

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Asymmetry Index on Marginal Homogeneity for Square Contingency Tables with Ordered Categories

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Open Journal of Statistics 2012年第2期2卷 198-203页

作者： Kouji tahata Kanau Kawasaki Sadao Tomizawa Department of Information Sciences Faculty of Science and Technology Tokyo University of Science Chiba Japan

For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The proposed measures lie between –1 to 1. When the marginal cumulative logistic model or the extended marginal homogeneity model holds, the proposed measures represent the degree of departure from marginal homogeneity. Using these measures, three kinds of unaided distance vision data are analyzed.

关键词： Marginal Homogeneity Marginal Cumulative Logistic Model Measure Square Contingency Table

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Decomposition of Independence Using the Logit Uniform Association Model and Equality of Concordance and Discordance for Two-Way Classifications

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Open Journal of Statistics 2015年第6期5卷 514-518页

作者： Kouji tahata Nobuko Miyamoto Sadao Tomizawa Department of Information Sciences Tokyo University of Science Chiba Japan

For two-way contingency tables with ordered categories, the present paper gives a theorem that the independence model holds if and only if the logit uniform association model holds and equality of concordance and discordance for all pairs of adjacent rows and all dichotomous collapsing of the columns holds. Using the theorem, we analyze the cross-classification of duodenal ulcer patients according to operation and dumping severity.

关键词： Concordance Discordance Independence Logit Uniform Association Model

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肝细胞癌后丙型肝炎患者直接抗病毒治疗的临床疗效与干扰素治疗相当

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临床肝胆病杂志 2020年第8期36卷 1767-1767页

作者： tahata Y SAKAMORI R URABE A 张雨温晓玉不详吉林大学第一医院感染病中心肝病科

【据《Hepatol Res》2020年7月报道】题:肝细胞癌后丙型肝炎患者直接抗病毒治疗的临床疗效与干扰素治疗相当(作者tahata Y等)与干扰素相比,直接抗病毒治疗对肝细胞癌(HCC)的复发和生存率的影响尚不清楚。来自大阪大学胃肠病与肝病学研... 详细信息

【据《Hepatol Res》2020年7月报道】题:肝细胞癌后丙型肝炎患者直接抗病毒治疗的临床疗效与干扰素治疗相当(作者tahata Y等)与干扰素相比,直接抗病毒治疗对肝细胞癌(HCC)的复发和生存率的影响尚不清楚。来自大阪大学胃肠病与肝病学研究院的tahata等对2005年1月-2017年11月在23家医院应用干扰素(n=88,IFN组)或直接抗病毒药物(n=250,DAA组)并获得持续病毒学应答(SVR)的338例慢性HCV感染且既往HCC治疗的患者进行了分析。采用倾向评分匹配法比较两组间累积肝癌复发率和生存率。

关键词：干扰素治疗丙型肝炎患者直接抗病毒药物肝病学持续病毒学应答肝细胞癌抗病毒治疗大阪大学

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