1987 Fiscal Year Final Research Report Summary
DISTRIBUTION OF MANGROVE SWAMP AND PALEO-ENVIRONMENT OF THE NISHIKUROSAWA AGE
| Project/Area Number |
60480026
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | FACULTY OF GENERAL EDUCATION, YAMAGATA UNIVERSITY |
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Principal Investigator |
YAMANOI TOHRU [FUCULTY OF GENERAL EDUCATION, YAMAGATA UNIVERSITY], 教養部, 助教授 (00111328)
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| Co-Investigator(Kenkyū-buntansha) |
TSUDA KARYU [ADMINISTRATION BUREAU, NIIGATA UNIVERSITY]
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| Project Period (FY) |
1985 – 1987
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| Keywords | Nishikurosawa age / Early Middle Mocene time / Pollen fossil / Mangrove plant Kurosedani Formation / 黒瀬谷層 / 古環境 |
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| Research Abstract |
The "Nishikurosawa age" is defined as a climatic optimum period in Early Middle Miocene time. In this study we discussed the conditions of paleo-environ- ment of this age from the view point of the palynology. The results obtained are summarized as follows:
(1) A characteristic of the pollen assemblages of this age is dominated by such plants as Carya, evergreen quercus and Liquidambar, and is accompanied by Dacrydium.
(2) The upper limit of the Nishikurosawa age is clarified stratigraphically and palynologically in the core sequence of the "Kurokawa drilling" in northern part of Niigata Prefecture. While, as the lower limit, it seems to be the most probable that, is setuated at the lower part of the Oyama Formation of Shyonai district in Yamagata Prefecture.
(3) The distributional of northern limit of mangrove plant fossil (pollen grain) of this age is in the Orito Formation in Sado Island. However, if an analysis will be done by the samples which sedimented at more close to the sea coas
… More
t, there is some possibility of discovery for northern limit of higher latitude.
(4) The pollen fossils of mangrove plants are very common in the lower half of the Kurosedani Formation in Toyama Prefecture. Especially they are contained abundantly in the areas along Rever Tochizu and around Kasuga, there occurred two gerena of Excoecaria and Sonneratia as a manglove plant in high ratio. The sediments of the lower half of the Kurosedani Formation were deposited around the delta which was constucted at the mouth of Paleo-River Zintsu. Such an environment was very suitable for the mangrove swamp vegetation. The manglove flora of the Kurosedani Formation, as compared with those of the recent South- eastern asia, is safely corelative with that of Iriomote Island or those of more southern regions. It is the same case with the fossil molluscs of the Kurosedani Formation. In the manglove swamps around the delta of the Paloe- River Zintsu, such zonation of mangrove genera was seen in the following order from the low-tide line to the high-tide line. Sonneratia-Avicennia (at sandy place) / Rhizophora (at muddy place) -> Bruguiera (with a little of Celiops, Scypiphora and Nypa) -> Excoecaria. Less
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Research Products
(4 results)
