菲律宾海板块俯冲与岛弧演化的钻探靶区研究

Study on drilling target area of subduction of Philippine Sea plate and island arc evolution

  • 摘要: 菲律宾海板块因其位于欧亚板块、太平洋板块和印-澳板块交汇处的特殊位置,蕴含丰富的前沿地球科学问题,是构造地质学、沉积学、古海洋学以及全球变化研究的热点地区,已经开展了25个航次、98个站位、218口深海钻探井工作。系统梳理了已有的DSDP-ODP-IODP大洋科学钻探航次目标与初步结果,认为绝大部分钻探航次以“弧前增生楔结构和孕震机理”及“岛弧岩浆作用和大陆边缘陆壳增生机制”为主要科学目标,且集中在以日本南海海槽、伊豆-小笠原-马里亚纳岛弧区域为主的活动大陆边缘,少量钻孔分布在板块内部的海底高原和海脊地区,深海盆区仅有零星钻孔分布。而上述地区同样是制约西太平洋构造沉积演化研究的关键区域,诸如花东海盆的年代属性、俯冲带和岛弧形成过程、菲律宾海板块演化以及风尘沉积等关键科学问题需要在此寻找答案。基于已有研究与实测资料,在九州-帕劳海脊三联点区建设性地提出了5个大洋科学钻探站位,并进行了初步钻探预测,旨在阐述俯冲启动机制和岛弧早期演化、厘定三联点岩浆作用和古环境重建等3个科学目标。菲律宾海钻探井位建议与实施,不仅对解决菲律宾海构造演化与沉积效应的关键科学问题有重要科学意义,而且对支撑未来我国自有大洋钻探船深海科学钻探需求具有现实意义。

     

    Abstract: The Philippine Sea plate, which is located at the junction of the Eurasian plate, the Pacific plate, and the India-Australia plate, contains a wealth of cutting-edge geoscience issues, including tectonic, sedimentology, and paleoceanography. A total of 25 ocean drilling expeditions have been carried and 218 drilling holes have been completed in this area. This paper highlights the scientific goals and preliminary results for the previous expeditions systematically. Previous expeditions focused on issues such as the structure of forearc accretion, the seismogenic mechanism, and the magmatism of island arc. Most of these holes were drilled at the subduction zones, mainly located at the Nankai Trough and the Izu-Bonin-Mariana Trough. Meanwhile, a few drilling holes were from the oceanic plateau, submarine rigdes, and oceanic basin. Oceanic plateau, ridges and basins are preferred areas for revealing nature of Huatung basin, initiation process of subduction and arc magnatism, and aeolian deposition. Based on newly acquired multichannel seismic data, five ocean drilling sites are proposed which are located at the triple junction area of the Kyushu Palau Ridge and the lithology and sequence for the proposed holes are predicted preliminarily. The proposed holes will achieve the scientific goals of revealling the subduction initiation mechanism determining the triple junction magmatism, and paleoenvironment reconstruction. Thus, the future drilling program will support the future scientific drilling needs of Chinese ocean drilling vessel.

     

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