论文部分内容阅读
1 引 言 许多关于岛弧形成和演化、弧后和弧前演化及弧岩浆过程的思想是以菲律宾海板块的构造解释为根据的(图1)。从运动学和作用力观点来看,西太平洋的板块运动史对理解东南亚的发展和欧亚东缘边缘盆地的成因也是关键的。理解西太平洋构造演化的一个重要单元是菲律宾海板块。可是,此板块为俯冲带所围绕,使得它与洋脊体系相隔开,它缺失热点轨迹,并缺失增生边界。所以,它相对其它主板块的现代运动很难测定(Seno等,1993),是一个其运动史知道很少的重要板块。因此对它的成因还有不同看法。 古地磁可提供解决菲律宾海板块运动和成因的一些问题的一种手段。得自陆地和海洋钻探的倾角资料都一致地指出此板块向北移动。然而偏角资料的解释不清楚。仅有的海洋钻探的偏角结果得自ODP126航次,它表明自晚第三纪中期以来有很大顺时针转动。陆地研究也指出有偏角变化,表明有巨大顺时针转动,但对这些结果的解释有争论,因为所有采样位置都位于板块的东缘,那里有局部构造转动是一种可能的解释。在那里,自始新世来的一些弧后扩
1 INTRODUCTION Much of the thinking on island arc formation and evolution, backarc and pre-arc evolution, and arc magma processes is based on tectonic interpretation of the Philippine Sea plate (Fig. 1). In terms of kinematics and force, the history of the plate motion in the western Pacific is also crucial for understanding the development of Southeast Asia and the genesis of the marginal basins on the eastern Eurasian rim. An important element to understand the tectonic evolution in the western Pacific is the Philippine Sea plate. However, this plate is surrounded by subduction zones that separate it from the ridge system, which lacks hot spot trajectories and lacks accretionary boundaries. Therefore, it is difficult to measure the modern motion relative to other main plates (Seno et al., 1993) and is an important plate with little knowledge of its movement history. So there are different reasons for its cause. Palaeomagnetism can provide a solution to some of the problems of the movement and causes of the Philippine Sea plate. Incline data obtained from both land and ocean drilling consistently indicate that the plate moved north. However, the interpretation of declination data is not clear. The declination of the only offshore drilling results from the ODP 126 voyage, which indicates a significant clockwise turn since the middle of the late Tertiary. Terrestrial studies have also pointed to declination, indicating a significant clockwise rotation, but the interpretation of these results is controversial as all sampling locations are located on the eastern edge of the plate where local tectonic rotation is a possible explanation. There, some arc backwards from Eocene