2013 Fiscal Year Final Research Report
Reconstruction of Mesozoic Ocean Plate Stratigraphy and biogenic silica history in the high-latitude southern Panthalassa Ocean
| Project/Area Number |
23540528
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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 |
Geology
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| Research Institution | Utsunomiya University |
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Principal Investigator |
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| Research Collaborator |
BERNHARD Spörli K. University of Auckland, 博士
GRANT-MACKIE J. A. University of Auckland, 博士
CAMPBELL H. J. GNS Science, Campbell
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| Project Period (FY) |
2011 – 2013
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| Keywords | 海洋プレート層序 / パンサラサ海 / 高緯度帯 / 三畳紀 / 層状チャート / 生物源シリカ / 堆積相 / 放散虫化石 |
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| Research Abstract |
The bedded chert section on Motutapu Island, near Auckland is comprised of black laminated chert and red chert. Based on conodont biostratigraphy, the black chert is Spathian and the red chert is early to middle Anisian in age. In order to unravel the sedimentary facies and microstructure of the bedded chert, high-resolution SEM observations were carried out on HF-treated chert slabs that were collected through the section. Three microfacies have been recognized: ordinary pelagic chert facies (G2), pelagic siliceous clay facies (E1/E2) and biogenic siliceous constituent facies (G1) comprising abundant sponge spicules and radiolarian shells. Facies G2 has a high biosiliceous component (10-30%) which appears as mostly dissolved and/or poorly preserved microfossils. Facies E1/E2 has a siliceous clay matrix with a low content (1-10%) of biosiliceous shells and spicules. Facies G1 is characterized by densely packed, non-cemented sponge spicules and spherical radiolarian shells.
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