2015 Fiscal Year Final Research Report
On the study of explosive biodiversification event on pelagic deep-sea bottoms in the Early Phanerozoic Eon
| Project/Area Number |
24540496
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Meiji University (2014-2015)
The University of Tokyo (2012-2013) |
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Principal Investigator |
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| Project Period (FY) |
2012-04-01 – 2016-03-31
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| Keywords | 生痕化石 / 放散虫チャート / オルドビス紀 |
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| Outline of Final Research Achievements |
Explosive increase in biodiversification is confirmed in the shallow epicontinental settings in the Middle Ordovician age. Trace fossils in well-dated radiolarian cherts are examined to clarify if the event also had occurred on pelagic deep ocean bottoms. Tiny trace fossils are confirmed in the upper Cambrian cherts of the Lachlan Fold Belt, the deposits of Panthalassan Ocean in Australia, while no trace fossils are found in the cherts of Kazakhstan, the deposits of Tethyan Ocean. In the Middle Ordovician cherts, trace fossils have been commonly found in all five examined areas including the deposits of Iapetan Ocean.
The cause of the difference in the regions found in the upper Cambrian rocks is ascribed to the depositional environment. Red chert in Kazakhstan had been deposited under well-oxygenated environment, but poverty of foods prevented migration of benthic animals into the pelagic realm. The Great Ordovician Biodiversification Event is also confirmed in pelagic ocean bottom.
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| Free Research Field |
地質学
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