| Project/Area Number |
20740300
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Kumamoto University |
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Principal Investigator |
KOMATSU Toshifumi Kumamoto University, 大学院・自然科学研究科, 准教授 (40336201)
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| Project Period (FY) |
2008 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2010: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2009: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2008: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 地質学 / 古生物学 / 進化 / 古環境 / 多様性 / 大量絶滅 / ベトナム / 放散 / 回復 / 三畳紀 / 二枚貝 / 古生代末大量絶滅 / 堆積環境 / アンモナイト / 系統 / 東アジア / 層位 / 古生物 |
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| Research Abstract |
In North Vietnam, Lower to Middle Triassic storm- and wave-dominated shelf deposits are widely exposed and yield abundant Tethyan bivalves indicating recovery and diversification following the end-Permian mass extinction. I reconstructed bivalve assemblages from the Lower Triassic Lang Son and the Middle Triassic Na Khuat formations and the habitats of characteristic or dominant bivalve species on the basis of shell preservation and mode of occurrence.
In the Lower Triassic, epifaunal Claraia, Towapteria and Eumorphotis are abundant in shallow marine environments above storm-wave base, besides, Claraia is dominant in the assemblage in the muddy facies below storm-wave base. In the Middle Triassic, bivalve assemblages are composed mainly of shallow infaunal and semi-infaunal burrowers and epifaunal species, though in Vietnam the Lower Triassic Induan to early Olenekian bivalves are dominated by epifauna. Furthermore, the Middle Triassic bivalve assemblages are characterized by a diversity of infaunal species of Costatoria and Trigonodus. In the Middle Triassic Na Khuat Formation, bivalve assemblages from shallow marine environments above storm-wave base are characterized by infaunal species, such as Costatoria goldfussi and Trigonodus. Costatoria paucicostata and Hoernesia are abundant in the outer shelf environments below storm-wave base. In the eastern part of the Tethys, infaunal bivalves show a remarkable delay in recovering from the end-Permian mass extinction compared to epifaunal bivalves.
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