2016 Fiscal Year Final Research Report
Abnormal ocean circulation during Mesozoic green house era, reconstructed from geographic pattern of geochemical indicator
| Project/Area Number |
25800288
|
|---|
| Research Category |
Grant-in-Aid for Young Scientists (B)
|
| Allocation Type | Multi-year Fund |
|---|
| Research Field |
Stratigraphy/Paleontology
|
|---|
| Research Institution | Meiji University (2014-2016)
Kyushu University (2013) |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2013-04-01 – 2017-03-31
|
| Keywords | ジュラ紀 / 温室期 / 古太平洋 / 海洋循環 / 石灰岩 / 炭素同位体比 / 地域間対比 / 厚歯二枚貝 |
|---|
| Outline of Final Research Achievements |
Carbon isotope stratigraphy of the Late Jurassic and earliest Cretaceous was revealed from Torinosu-type limestone, which was deposited in a shallow-marine setting in the Paleo-Pacific Ocean, in Japan. The age-model was established using Sr isotope ratio and fossil occurrence. The composite δ13C profile from the two limestone sections can be correlated with the profiles of relevant ages from the Alpine Tethyan region. In addition, we found that δ13C values of the Torinosu-type limestone are ~1‰ lower than the Tethyan values in the late Kimmeridgian. This inter-regional difference gradually reduces and disappears in the late Tithonian. This isotopic homogenization is probably due to changes in the continental distribution and the global ocean circulation during this time.
In addition, I studied rudistid bivalve in Torinosu-type Limestone. I found primitive requieniidine rudists lived in shallow-water depositional environment in a calm setting on a small carbonate mound.
|
| Free Research Field |
地質学
|
