2017 Fiscal Year Final Research Report
Reconstruction of oceanic circulation patterns in the tropical Pacific across the early/middle Miocene boundary
| Project/Area Number |
15K17780
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Ibaraki University |
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Principal Investigator |
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | 赤道太平洋 / 前期中新世 / サーモクライン / 東西勾配 / インドネシア海峡 / 放散虫化石 / 地球温暖化 |
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| Outline of Final Research Achievements |
In this study, we reconstruct the changes in tropical oceanic circulation patterns in the Pacific across the early/middle Miocene boundary based on radiolarian assemblages obtained at Integrated Ocean Drilling Program Site U1335 in the eastern tropical Pacific.
Beginning in the latest early Miocene (~17 Ma) radiolarian assemblages were dominated by different taxa in the eastern and western tropical Pacific. This pattern is interpreted as indicating a shallower thermocline in the east and a deeper thermocline in the west, based on the relative abundance of the upwelling taxa. There is an overall increasing trend in this difference since the latest early Miocene. We tie these events to the effective closure of the Indo-Pacific seaway and the development of a substantial western Pacific warm pool along with the development of a strong Equatorial Undercurrent.
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| Free Research Field |
微古生物学
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