陆缘扩张型地洼盆地系及其形成机制探讨

本文提出“陆缘扩张型地洼盆地系”这一概念,以突出表述分布于东亚陆缘壳体之上,形成于地洼余动期的张性地洼盆地系列的壳体演化—动力环境。指出陆缘海中的裂陷盆地的成因难于与大洋板块俯冲导致弧后扩张的理论模式相联系,也不同于大西洋型盆地,而是大陆地壳演化到地洼余动期,并经历过华夏期地洼型造山运动之后拉伸裂陷的结果。论证了“岩石圈底层剥落、华夏期地洼造山带拉伸裂陷”是东亚陆缘扩张发生的一种重要机制,进而建立了由华夏期地洼型挤压造山带到盆岭型构造带和陆缘海盆地系的构造发展模式。

ON THE DIWA BASIN SYSTEM OF CONTINENTAL MARGIN SPREADING TYPE AND ITS GENETIC MECHANISM

A concept, "the diwa basin system of continental margin spreading type", has been put forward to express the crustobody evolutional-geodynamic environment of the exten-sional diwa basins distributed in the East Asia continental margin crustobody and formed in the residual-mobility period of diwa stage. It has been pointed out that the genesis of the taphrogenic basins in the continental marginal sea diwa regions does not have relation to the ideal model of back- arc spreading caused by subduction of oceanic plates; and the basins do not belong to the Atlantic type. In-fact, the basins are results of extension and taph-rogeny of the continental crust that has evolved to the residual-mobility period of diwa stage and has undergone the Cathaysian diwa oro-gensis. An important mechanism, " lower lithospheric delamination and extensional collapse of the Cathaysian diwa orogens" has been considered to explain the formation of the diwa basins of continental margin spreading type and a model has been built up to show the tectonic development from the Cathaysian diwa-type orogens to the basin-and-range-type structural zones, then to the continental marginal sea basins.