2003 Fiscal Year Final Research Report Summary
Interaction between Geosphere and Biosphere in the Early Paleozoic of the Tethys
| Project/Area Number |
12573008
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 海外学術 |
|---|
| Research Field |
Geology
|
|---|
| Research Institution | THE UNIVERSITY OF TOKYO |
|---|
Principal Investigator |
MATUMOTO Ryo The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (40011762)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAKUWA Yoshitaka The University of Tokyo, Graduate School of Artsand Science, Research Associate, 大学院・総合文化研究科, 助手 (70124667)
OGIHARA Shigenori The University of Tokyo, Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (50214044)
TANABE Kazushige The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (20108640)
KANO Akihiko Hiroshima University, Faculty of Science, Research Associate, 理学部, 助手 (60231263)
TAZAWA Jun-ichi Niigata University, Faculty of Science, Professor, 理学部, 教授 (50108453)
|
|---|
| Project Period (FY) |
2000 – 2003
|
| Keywords | Carbon isotope / Strontium isotope / Dolomite / Iran / China / Precambrian / Devonian / Ordovicia |
|---|
| Research Abstract |
This march project covers the environmental change and biotic evolution in the Uppermost part of the Precambrian to the Lower Paleozoic. The methods of study includes 1. Field work in Iran and south China, 2, Observation of samples under microscope, 3. Geochemical analysis of samples for trace element concentrations, carbon and strontium isotopic ratio and biomarkers. Main highlights of individual research program am as follows.
1.Environment and evolution in the Uppermost Precambrian ; Typical glacier deposits (diamictite of the Marinoan Ice Age) well develop in the South China platform. The diamictite is overlain by ca.4 m thick dolomite bed. The dolomite bed is considered as "Cap Carbonate" immediately after the "Snowball Earth". Detailed petrographic and chemical analysis of the dolomite has revealed that the dolomite was formed as an accumulation of peloids of primary dolomite under methane induced anoxic deep ocean environment, Another ice age was indicated by isotopic evidence at about 50 meters above the dolomite. Black shale between the two ice ages contains common chert nodules which yield abundant remains of microbial activity.
2.The Ordovician-Silurian boundary and the Upper most part of the Devonian were also the major targets of the project. As for the former, we found new outcrop in South China, and observed continuous carbonate bed near the boundary within black shale. For the latter, clay mineral composition, organic material and isotopic analysis has strongly suggested that dissociation of gas hydrates must have played an important role in drastic change of global environments
|
