从西太平洋板块构造探讨东海陆架盆地形成机制和类型划分

东海陆架盆地位于亚洲板块东南缘,是西太平洋构造体系的一部分,其形成和发展与西太平洋板块活动有关.白垩纪—古新世,库拉板块和太平洋板块作NNW向运动并俯冲,左旋应力场使亚洲大陆东南缘产生一系列NE向断裂,引起地幔上拱,诱发了盆地西带裂谷式断陷的发展.古新世晚期由于太平洋板块洋脊俯冲,日本海(西部)第一次拉张.地幔面起伏的调整结束了裂陷盆地的发育.始新世晚期,太平洋板块俯冲方向由NNW转为WNW,右旋应力场控制了盆地东部始新世断拗的发育.渐新世初,由于太平洋板块俯冲,日本海(东南部)开始了第二次拉张.东海陆架盆地东部断坳带转为坳陷带.中新世末,太平洋板块运动速度加快,热效应导致前缘隆起拉裂,形成冲绳海槽盆地.向西挤压一走滑使陆架盆地东部坳陷带褶皱回返,结束了盆地发展.可以认为,东海陆架盆地西部古新世裂陷带是大陆边缘裂谷盆地;东部渐新世一中新世坳陷带是大陆边缘前陆盆地(弧后).

DISCUSSION ON BASIN FORMATION MECHANISM AND BASIN TYPES IN EAST CHINA SEA CONTINENTAL SHELF BASIN BASED ON WEST PACIFIC PLATE TECTONICS

The East China Sea shelf basin, located on the southeastern margin of Asian Plate, is one of the West Pacific tectonic system. Its formation and development were related to the plate tectonics. The Kula Plate and Pacific Plate moved in NNW direction and subducted during Cretacerous-Palaeocene period. A series of NE trend faults were developed on the southeastern margin of Asian continent and the mantle was arched due to sinistral stresses, thus induced rift-subsidence in the western part of the basin. Due to the subduction of Pacific Plate at late Palaeocene,the western part of Japan Sea was pulled-apart. The adjustment of mantle surface relief ended the rift basin development. At late Eocene, the Pacific Plate subduction direction were changed from NNW to WNW, and the development of Eocene fault depressions in the eastern part of the basin were controlled by dextral stresses. The Japan Sea was begun with the second pull-apart in its southeastern part at early Oligocene due to the subduction of Pacific Plate. And the eastern part of the East Chi-na Sea shelf basin was changed into depression from fault-depression. At end of Miocene, the Pacific Plate tectionics was accelerated; the heat flow caused the front margin uplifted and pulled-apart, forming Okinawa Trough basin. The westward compression and strike-slip made the eastern depression of the shelf basin fold again, thus ending the development of the basin. It can be believed that the Palaeocene rift in the western part of Sea China Sea shelf basin is continental marginal rift basin, and the Oligocene-Miocene depression in its eastern part is foreland basin (back-arc) on the continental margin .