Isotopic anomalies at the Precambrian-Cambrian boundary
Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||The University of Tokyo |
MATSUMOTO Ryo UNIVERSITY OF TOKYO,Graduate School of Sciences, Professor, 大学院・理学系研究科, 教授 (40011762)
ウッシュマンド A. イラン地球科学技術研究所, 所長
UENO Katsumi Tsukuba Univ., Institute of Geoscience, Lecturer, 地球科学系, 講師 (90241786)
KANO Akihiro Hiroshima Uni., Faculty of Science, Assistant, 理学部, 助手 (60231263)
KAKUWA Yoshitaka UNIVERSITY OF TOKYO,Graduate School Arts and Sciences, Assistant, 大学院・総合文化研究科, 助手 (70124667)
HUSHMAND A. Research Institute of Earth Sciences, Director
ハムディ B. イラン地球科学研究所, 教授
吉田 鎮男 東京大学, 大学院・理学系研究科, 助教授 (50011656)
|Project Period (FY)
1995 – 1997
Completed (Fiscal Year 1997)
|Budget Amount *help
¥9,300,000 (Direct Cost: ¥9,300,000)
Fiscal Year 1997: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1996: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1995: ¥4,300,000 (Direct Cost: ¥4,300,000)
|Keywords||Precambrian / Cambrian boundary / Cambrian explosion / F / F boundary / Carbon isotope / Rare earth elements / Cerium anomaly / Redox potential / P / T境界 / アバデ- / ジョルファ / 炭素同位体層序 / イラン / 中国 / 炭素同位体 / カンブリア / 絶滅事変 / 地球環境 / 二畳-三畳境界 / エルブールズ / 先カンブリア系 / 先カンブリア-カンブリア境界 / 炭酸塩岩 / 石炭系 / 周期堆積 / エディアカラ動物群|
This project was originaly intended to elucidate the nature of the Precambrian/Cambrian boundary event. However, the actual field work plans were reorganized and expanded towards the entire Paleozoic sections in the course of the joint study with the Iranian geologist group. Because the P/C boundary event was believed to be characterized only through the comparison with the other Paleozoic boundary events such as F/F boundary and P/T boundary. We have obtained the following major results concerning the chemo-stratigraphy and environmental changes of the Paleozoic world.
1. Negative and positive carbon isotopic anomaly have been recognized just below and bove the P/C boundary. The formaer and the latter are interpreted to correspond to mass extinction of Precambrian fauna and explosive diversification of the Paleozoic type fauna. Moreover, strong positive anomaly was observed in the late Cambrian strata.
2. Moderate negative carbon anomaly in the upper Devonian is probably attributed to the Famenian/Frasnian boundary events.
3. Cyclic changes in carbon isotopic composition recognized in the Carboniferous-Permian may reflect the glacier-interglacier cycles.
4. Chondrite-normalized REEs patterns show interesting secular variations. Strong negative Ce anomaly occurs in the Cambrian explosion intervals whereas the remaining Paleozoic sections show normal pattern, suggesting that the Cambrian explosion was associated with oxygenated ocean while the entire Paleozoic ocean was characrerized by reducing environment.
Report (4 results)
Research Products (28 results)