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2019 Fiscal Year Final Research Report

Constraints on Cu and Zn concentrations in Paleoproterozoic seawater.

Research Project

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Project/Area Number 17H04858
Research Category

Grant-in-Aid for Young Scientists (A)

Allocation TypeSingle-year Grants
Research Field Geology
Research InstitutionThe University of Tokyo

Principal Investigator

Sawaki Yusuke  東京大学, 大学院総合文化研究科, 助教 (00635063)

Project Period (FY) 2017-04-01 – 2020-03-31
Keywords前期原生代 / 掘削試料 / 銅同位体比 / 亜鉛同位体比 / 真核生物
Outline of Final Research Achievements

Trace element concentration in seawater is a crucial component in regulating marine biological productivity. Purpose of this study is elucidating surface environmental changes, especially focusing on marine Zn concentration, during the Paleoproterozoic. We conducted on-land drilling to collect fresh sedimentary rocks in Gabonese Republic, where Paleoproterozoic strata well crop out. As a consequence of analyses, we obtained new understandings as follows. (1) Appearance of eukaryote-like fossils dates back to approximately 2.2 Ga. (2) Oxic conditions locally existed in paleo-ocean in the Gabonese Republic. (3) Eukaryotes require more Zn than prokaryotes. Marine Zn concentration was elevated in association with the Great Oxidation Event during the Paleoproterozoic.

Free Research Field

地球史

Academic Significance and Societal Importance of the Research Achievements

本研究の結果により、まずは真核生物の出現時期が従来考えられていたよりも1億年古く、22億年前まで遡る事が新たに明らかになった。また、前期原生代に大気海洋が酸化的になった事により、海洋中の亜鉛が溶存態として存在できるようになったはずである。本研究による分析結果は海水亜鉛濃度が増加した事を示している。前期原生代の地層から真核生物化石が見つかるようになるのは、海水亜鉛が上昇し、亜鉛を多量に必要とする真核生物の個体数が増加したからであると考える事ができる。

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Published: 2021-02-19  

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