2013 Fiscal Year Final Research Report
Deciphering surface environment in the late Proterozoic using Re-Os measurement.
| Project/Area Number |
24840021
|
|---|
| Research Category |
Grant-in-Aid for Research Activity Start-up
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Geology
|
|---|
| Research Institution | Tokyo Institute of Technology |
|---|
Principal Investigator |
SAWAKI Yusuke 東京工業大学, 理工学研究科, 助教 (00635063)
|
|---|
| Project Period (FY) |
2012-08-31 – 2014-03-31
|
| Keywords | 後期原生代 / レニウム・オスミウム / Sulfidic / 南中国三峡地域 |
|---|
| Research Abstract |
Global correlation of Precambrian stratigraphic successions can be conducted by the coarse resolution off biostratigraphic and chemostratigraphic records, because of the scarcity of precise U-Pb zircon dating. Re-Os isotope systems of organic matter-rich black shales became one of the reliable indicators of the depositional age, due to the recent developments in Re-Os analysis.
Rock powders were prepared from drill-core collected at Three Gorge, South China. Re and Os isotopic compositions were measured by TIMS at JAMSTEC. The 187Re/188Os and 187Os/188Os ratios of the black shales show linearity in the isochron plot. The model 3 isochron ages were 578 Ma (error is 12 Ma) for the black shale at the lower Member 4 of the Doushantuo Fm, with initial 187Os/188Os ratios of 1.02 (2SD=0.09). The Re-Os isochron plot for all analyses yields an age of 512 (error is 12 Ma) for the black shale at the bottom of the Shuijingtuo Fm, with initial 187Os/188Os ratios of 1.15 (2SD=0.19).
|
