论菲律宾海板块大地构造分区

Discussion on the tectonic division of the Philippine Sea Plate

菲律宾海板块是毗邻中国大陆的一个独特的小型板块。除南端表现十分复杂外,它的构造边界多以海沟为界,比较清楚,然而次级大地构造单元划分则比较复杂。本文根据近年来的研究成果,按照块体构造理论注重统一的地球物理场、相似的地壳结构、有机的成因联系等3个基本原则,将菲律宾海板块划分为3个具有不同构造演化特征的单元,即西菲律宾海块体、四国—帕里西维拉块体和伊豆—博宁—马里亚纳块体。西菲律宾海块体包括两部分:一个是西菲律宾海盆,始新世以来受太平洋板块和印澳板块近南北向的相对俯冲作用影响,并顺时针旋转形成了现今的构造样式,于30 Ma左右停止扩张。另一个包括大东盆岭、花东盆地、帕劳海盆和吕宋岛弧蛇绿岩等洋壳在内的白垩纪洋盆。根据形成年代和形成时的扩张方向可将四国—帕里西维拉块体分为两部分:四国海盆和帕里西维拉海盆,两者以索夫干断裂为界。伊豆—博宁—马里亚纳块体沿博宁高原南缘分为南北两部分,两者表现出不同的地质特征。

Philippine Sea Plate（PSP） is a unique minor plate close to China mainland. Except for the complicated southern part, the tectonic boundaries of the PSP are clear, most of which consist of trenches. However, it is hard to divide the plate into the secondary even three-level units. Based on the research in the recent years and referring to block tectonic theory with the principals of unitary geophysical field, similar crustal structure and organic genesis, the PSP is partitioned into three units with different evolutionary history, i. e. West Philippine Sea Block （WPSB）, Shikoku-Parece Vela Block （SPB） and Izu-Bonin-Mariana Block （IBMB）. The WPSB consists of two major parts ,Cenozoic oceanic basin（west Philippine Basin）which was opened between two opposed subduction zones,rotated clockwise to the present place and culminated at ca. 30 Ma, and Cretaceous oceanic basin consisting of Daito Basin and ridge province, Huatung Basin, Palau Basin and ophiolite of Luzon arc. The SPB can be divided further into Shikoku Basin and Parece Vela Basin by the Sofugan Fault. The IBMB displays the different geological features in the south and north of the Bonin（Ogasawara） Plateau.