Holocene diatom floras and environmental changes of lagoon-lake deposits in the northern Echigo Plain, central Japan
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- YASUI Satoshi
- Koka Foundation Survey Corporation Inc.
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- YOSHIDA Mamiko
- 新潟大学大学院自然科学研究科
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- URABE Atsushi
- 新潟大学災害復興研究センター
Bibliographic Information
- Other Title
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- 越後平野北部の沿岸湖沼の珪藻化石群集と環境変遷史
- エチゴ ヘイヤ ホクブ ノ エンガン コショウ ノ ケイソウ カセキ グンシュウ ト カンキョウ ヘンセンシ
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Abstract
A detailed diatom analysis of one drilling core was carried out in the Fukushima-gata Lagoon area of the northern part of the Echigo Plain, which is situated in the inlet side of the Kitakanbara-gata Lagoon. 11 diatom divisions were detected and correlated with divisions of the Shiunji-gata Lagoon area (Yasui et al. 2002) situated in the inside part of the Kitakanbara-gata Lagoon. The characteristics of diatom assemblages and Holocene sedimentary environments of the Kitakanbara-gata Lagoon are discussed in this paper. Diatom assemblages of the Kitakanbara-gata Lagoon were characterized by flourish or decline of several maker planktonic species. In the Fukushima-gata Lagoon area three types of diatom assemblage appeared repeatedly. The first type is dominated by Aulacoseira granulata, which indicates limnophilous fresh surface water, and may be caused by a closure of an inlet. The first type took the place of the second type dominating by Cyclotella caspia, which is caused by an inflow of marine water from an inlet opening. The third type is characterized by a low frequency of planktonic species, which indicates rheophilous fresh surface water or a reduction of water area. The Holocene sedimentary environments of the Kitakanbara-gata Lagoon are identified as follows on the basis of diatom divisions and ^<14>C datings. The Kitakanbara-gata Lagoon was under a brackish lake environment in ca. 8,000 yrs BP, and three periods of marine surface water expansion occurred at ca. 6,500, from ca. 6,000 to ca. 5,000 and at 3,500 yrs BP. In ca. 3,000 yrs BP, the connection of the water area between Fukushima-gata Lagoon and Shiunji-gata Lagoon areas in the Kitakanbara-gata Lagoon were disappeared.
Journal
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- Earth Science (Chikyu Kagaku)
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Earth Science (Chikyu Kagaku) 61 (1), 49-62, 2007
The Association for the Geological Collaboration in Japan
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Details 詳細情報について
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- CRID
- 1390282679209693824
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- NII Article ID
- 110006163706
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- NII Book ID
- AN00141269
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- ISSN
- 21897212
- 03666611
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- NDL BIB ID
- 8663509
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- CiNii Articles
- KAKEN
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- Abstract License Flag
- Disallowed
