西太平洋边缘构造特征及其演化

西太平洋边缘构造带是地球上规模最大最复杂的板块边界,以台湾和马鲁古海为界,自北往南大致可以分为3段。北段是典型的沟-弧-盆体系,千岛海盆、日本海盆及冲绳海槽均为典型的弧后扩张盆地。中段菲律宾岛弧构造带为双向俯冲带,构造复杂,新生代经历大的位移和重组,使得欧亚大陆边缘的南海、苏禄海和苏拉威西海成因存在很大的争议。南段新几内亚—所罗门构造带是太平洋板块、印度—澳大利亚及欧亚板块共同作用的结果,既有不同阶段的俯冲、碰撞,也有大规模的走滑与弧后的扩张,其间既有新扩张的海盆,又有正在俯冲消亡的海盆。台湾岛处于枢纽部位,欧亚板块在此被撕裂,南部欧亚大陆边缘南海洋壳沿马尼拉海沟俯冲于菲律宾岛弧之下,而北部菲律宾海洋壳沿琉球海沟俯冲欧亚大陆之下。马鲁古海是西太平洋板块边界又一转折点,马鲁古海板块往东下插于哈马黑拉之下,往西下插于桑义赫弧,形成反U形双向俯冲汇聚带,其洋壳板块已基本全部消失,致使哈马黑拉弧与桑义赫弧形成弧-弧碰撞。

The tectonic features and evolution of the west Pacific margin

The structural zone of the western Pacific margin is the biggest and most complex plate boundary in the earth. Bounded at Taiwan and the Molucca Sea, it can be divided into 3 sections from the north to the south. The north part, from Kurile to Ryukyu, is a typical trench-arc-basin system, and Kurile basin, Japan Sea and Okinawa trough constitute back arc basin. The central part, the Philippine structural zone, is characterized by complex double subduction. It underwent large displacement and reconstruction in Cenozoic and resulted in much debate for the origin of the South China Sea, Sulu Sea and Celebes Sea. The south part, the New Guinea-Solomon structural zone, resulted from compression and collision among Pacific, Indian and Eurasian plate, with large amounts of strike and back arc spreading. There are new spreading basins and subducting basins among the structural zones. The Taiwan Island is located at the junction, in which the Eurasian plate was torn. Eurasian plate margin subducted eastward beneath the Philippine arc along Manila Trench in the south, while Philippine Sea plate subducted northeastward beneath Eurasian plate along Ryukyu Trench in the north. Molucca Sea is another junction on the west Pacific margin, in which the oceanic lithosphere plate subducted westward beneath Sangihe arc and eastward beneath Halmahera arc, forming reversal U-shaped double subduction zone. Halmahera arc collided with Sangihe arc due to the almost disappearance of the oceanic plate.