菲律宾海盆磁条带特征及61 Ma以来的海底扩张过程重建

菲律宾海盆是西太平洋最大的边缘海盆地，作为地球上最壮观的“沟-弧-盆”体系的重要组成部分，其成因及构造演化可有效约束西太平洋洋陆过渡带的复杂动力学过程。海底磁异常条带是海底扩张的重要依据，其几何形态能够反映海底扩张的时间、方向及速率，为研究海盆的海底扩张过程提供重要信息。菲律宾海盆的次级海盆—西菲律宾海盆、四国海盆地磁异常表现为明显的条带状异常特征，帕里西维拉海盆内的磁条带特征虽不明显，但仍能看出南北向的分带现象。对海盆内的磁异常条带进行系统的分析、对比与解释，将菲律宾海盆划分为7个扩张阶段，构建了菲律宾海盆61 Ma以来的阶段性扩张模型。揭示了边缘海盆构造演化的一般规律及扩张过程为岛弧裂解、高速弧后扩张、慢速弧后扩张和扩张后作用4个阶段。

CHARACTERISTICS OF MAGNETIC LINEATIONS AND RECONSTRUCTION OF SEAFLOOR SPREADING PROCESSES OF THE PHILIPPINE SEA BASIN SINCE 61 MA

The Philippine Sea Basin is the largest marginal basin in the Western Pacific. As an important part of the most spectacular trench-arc-basin system in the world, the formation and tectonic evolution of the Philippine Sea Basin can constrain the complex kinetic process of the ocean-continent transitional zone in the Western Pacific effectively. Magnetic lineations are an important evidence of seafloor spreading and their geometrical morphology can reflect the time, direction and speed of the seafloor spreading, which provide crucial information for reconstruction of the opening history of ocean basins. The magnetic anomalies in the West Philippine Basin and Shikoku Basin occur in an obvious banded pattern and the north-south zonation can be recognized in the Parece Vela Basin, although the characteristics of magnetic lineations are not distinct. Based on the analysis, comparison and interpretation of these magnetic lineations, the Philippine Sea Basin has passed seven spreading stages and a scenario of evolution from 61 Ma to present was proposed. Furthermore, the tectonic evolution and general opening processes of the marginal basins starts from rifting, and is followed by back-arc spreading with high speed, back-arc spreading with low speed, and the tectonic activities after opening.