新潟県東頸城丘陵東部の魚沼層群の層序と層相
スポンサーリンク
概要
- 論文の詳細を見る
The Plio-Pleistocene Uonuma Group, well exposed in the Higashikubiki Hills of Niigata Prefecture, Central Japan, attains more than 2,500 m in total thickness. The Uonuma Group, partially interfingering with the Hachioji Formation of the Chuetsu Group, is divided into four parts, namely, lowermost, lower, middle and upper parts, based on the volcanic ash layer. Clastic sediments of the Uonuma Group mainly consist of irregular or cyclic alternation of gravel, sand and silt. Seventeen sets of ash layers, eight lapilli zones, six tuff breccia beds and fifteen marine beds are intercalated in the Uonuma Group. They are very important as marker beds for the establishment of stratigraphy. The marine beds interbedded with the non-marine beds suggest that transgressive and regressive processes were controlled probably by the eustatic sea-level changes or tectonic movement on more wide area than the Uonuma Sedimentary Basin. The change of sedimentary environment of the Uonuma Group was revealed by investigation of gravel composition, distribution of gravel beds and paleo-current. At the age of the Lowermost Part, deltas in the south and fan-deltas in the east were formed and rapidly filled up shallow sea. At the age of the Lower Part, there were alluvial fans in the east and fluvial plain with small river in the Matsudai area. Marshes spreaded widely. At the age of the Middle Part, alluvial fans in the east spreaded. Along the Shibumigawa Syncline, there was a fluvial plain with large river, marshes and flood plains, as large as Shinano River in the present Niigata Plain. There may have been the source of the river in the Nagano area to the southwest. At the age of the Upper Part, alluvial fans in the east spreaded widely, and the Uonuma Hills may uplifted partially. There was a fluvial plain continuously along the Shibumigawa Syncline. According as the slope of river became steep by the uplift of source areas, the large-sized gravels were transported from the south and deposited along the Shibumigawa Syncline.
- 地学団体研究会の論文
- 1988-03-25
著者
関連論文
- 新潟地域における第四紀層 : とくに魚沼層群とその相当層について
- 新潟積成盆地における西山・灰爪累層,魚沼層群の層序と古環境
- 新潟県魚沼地域の魚沼層群の層序と層相
- 新潟県東頸城丘陵東部の魚沼層群の層序と層相