南海西南次海盆后扩张期轴部海山的三维地壳结构及其形成演化模式

南海存在着强烈的后扩张期岩浆事件，并在海盆中形成了大量的海山。前人研究主要集中在海山的形态、岩性和形成时代上，对于其内部结构及形成机制的认识尚未深入。本申请通过在南海西南次海盆获得的主动源广角反射/折射地震数据，利用纵、横波联合反演技术对该海盆残留中脊附近海山的3D精细内部结构及物性特征进行刻画；同时开展被动源地震数据的接收函数研究，获得海山深部和下方的速度结构，系统探索后扩张期海山的构造-岩浆过程，并与东部次海盆区后扩张期海山进行比较，最终建立西南次海盆后扩张期海山的形成演化模式。该项目有助于增进南海后扩张期岩浆活动和演化过程的认识。

Post-spreading magmatism was extremely strong in the South China Sea, which leaded to the formation of post-spreading seamounts in the basin. Previous studies of the post-spreading seamounts concentrated on morphology, lithology and age, and the knowledge of the crustal structure and formation mechanism of them is still limited. This proposed study is mainly based on the active-source wide-angle seismic reflection/refraction data collected from the Southwest-Sub basin, South China Sea to determine the 3D detailed crustal structure and physical properties of the post-spreading seamount by using a joint P/S wave inversion method. In addition, we will simultaneously use teleseismic receiver functions to inverse the deep structure beneath the seamount based on the passive seismic data. All these work are conducted for a systematic study on the magma and tectonic processes of the post-spreading seamount at the fossil spreading center in the Southwest-Sub basin. Moreover a comparison of the seamounts between the Southwest-Sub basin and the East-Sub basin will be made. And finally we will present an evolutionary model of the post-spreading seamount of the Southwest-Sub basin. This proposed study will increase the knowledge of the post-spreading magmatism and evolution process of the South China Sea.