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

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.