西太平洋边缘海盆地的扩张过程和动力学背景

SPREADING AND DYNAMIC SETTING OF MARGINAL BASINS OF THE WESTERN PACIFIC

西太平洋集中发育了全球 75%的边缘海盆地 ,这些盆地形成于始新世、渐新世—中新世和晚中新世—第四纪 3个边缘海扩张幕。文中介绍了边缘海盆地的基本特征和发育模式 ,详细讨论了西北太平洋边缘海盆地周缘板块构造时空格架及其对边缘海盆地形成、演化和关闭过程的控制作用。太平洋板块的俯冲及俯冲带的后退 ,印度—亚洲大陆碰撞的远程效应以及澳洲与印度尼西亚的碰撞是边缘海盆地的 3个重要的区域性控制因素。印度—亚洲大陆的碰撞所形成的向东和东南的地幔流可能推动了东亚大陆东侧和南侧俯冲带的后退 ,并引发弧后扩张作用。同时 ,由这一碰撞引起的东亚大陆边缘NE或NNE向断裂的右旋走滑 ,进一步影响和控制了边缘海盆地的几何学特征及演化。澳大利亚和印度尼西亚的碰撞阻碍了俯冲带的后退 ,导致了南海、Sulu海和Celebes海盆地的扩张终止。同时这一碰撞推动菲律宾海板块向北运移 ,并使Bonin弧与中央日本碰撞 。

The more than 75 percent of the marginal basins found in the Earth today are concentrated in the western pacific. Opening of these basins occurred in three main spreading episodes: the Eocene,the Oligocene—Miocene, and the Late Miocene—Quaternary. The basic characteristics and forming models of marginal basins are introduced and evolution of plate tectonic framework around marginal basins and its control of the opening, evolution and closure of marginal basins are discussed in detail. Subduction and Rollback of the Pacific trench, the far field effect of collision of IndiaEurasia, and collision of Australia with Indonesia are three principal regional control factors for evolution of marginal basins. The eastward or southeastward mantle flow resulting from the collision of IndiaEurasia probably pushed rollback of slabs east and southeast to East Asian continent, further causing back arc spreading. At same time, the far field effect of this collision led to dextral strike slip along large intracontinental shear zones in the eastern Asian continental margin, which affected severely the opening of back arc basins and their geometry. The collision of Australia and Indonesia stopped the rollback of slabs, and as a result the South China Sea, the Sulu Sea and the Celebes Sea began to close. This collision also pushed Philippine Sea plate northward, and made the Bonin arc collide with the Center Japan, which caused closure of the Japan Sea.