Formation of the Tsunan Terraces in Tokamachi Basin, Niigata Prefecture, central Japan.
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Accession number;00A1002975
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| Title;Formation of the Tsunan Terraces in Tokamachi Basin, Niigata Prefecture, central Japan. |
| Author;
WATANABE HIDEO
(Mishimachomishimachu)
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Journal Title;Earth Science
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Journal Code:F0193A
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ISSN:0366-6611
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VOL.54;NO.5;PAGE.310-327(2000)
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| Figure&Table&Reference;FIG.14, TBL.1, REF.35 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Many Pleistocene to Holocene fluvial strath terraces formed by the Nakatsu River, a branch of the Shinano River, are distributed in the Tokamachi Basin, Niigata Prefecture, Japan. From the tephro-stratigraphic investigations of the eolian tephra horizons overlying terrace deposits, it is inferred that the age of Maibara II and Unoki terraces are 160-150ka, Hounokizaka 140-130ka, Kaisaka I 100-50ka, Kaisaka II 50ka, Shoumen 30ka, Oowarino I 10ka and Oowarino II most recent, respectively. The geomorphologic configuration of the terraces is controlled by the active structure of basement, which forms an asymmetric fold. Relatively high and tilted terraces are distributed at the northwest limb of the syncline where the basement beds have a high angle dip and the uplift rate is high. In contrast with this, on the other side of the syncline where the basement beds have a low angle dip and the uplift rate is low, relatively low and wide terraces are distributed. The development of the terraces was due to intermittent uplift. Active uplift occurred after the development of the Mibara II Terrace until the Kaisaka I Terrace and again the after the Shoumen Terrace until recent. Between the Kaisaka I and Shoumen terrace was a non-active phase. (author abst.) |
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