东南亚环形俯冲系统与西太平洋间深部通道（南纬0°-3°）各向异性和地幔交互机制研究

东南亚处于三面俯冲之中，构成了相对封闭的环形俯冲系统，但其东南部南纬0°-3°存在与西太平洋连通的深部通道，是进行地幔交互、物质交换与能量流通的重要场所。然而，目前对该深部通道在环形俯冲系统动力学过程中扮演怎样的角色尚缺少足够认知。研究该地区深部结构与地幔流动特征有助于厘清东南亚环形俯冲系统东南部与西太平洋之间的地幔交互机制，理解板片俯冲、地幔流动及岩浆流体活动之间的相互作用，为板块构造理论和地球动力学提供新认识。本申请项目拟使用该地区固定地震台网和临时台站所记录的大量体波到时数据，利用各向同性及各向异性地震层析成像最新技术进行近震和远震数据的联合反演，分别获得东南亚环形俯冲系统东南部的高分辨率P波速度、S波速度、泊松比与各向异性三维模型，进而对俯冲板片与深部通道形态、岩浆流体活动特征以及地幔对流模式开展详细研究，并结合多学科资料，最终为环形俯冲系统与西太平洋的地幔交互机制提供新的见解。

SE Asia is surrounded by subduction zones on its three sides, forming a relatively closed annular subduction system (ANSS). However, at 0°-3°S latitude of its southeast, a deep channel connecting the ANSS with the West Pacific is considered to exist, which may have a key effect on mantle interaction, material exchange, and energy transfer between the two regions. Unfortunately, so far it is not adequately known what a role the deep channel plays in geodynamic processes of the ANSS. Investigating the deep structure and mantle flow beneath this deep-channel region could help to clarify the mechanism of mantle interactions between the inside and outside of the ANSS. It will also improve our understanding of relationships among slab subduction, mantle convection, seismotectonics and volcanism. In addition, this study may shed new light on plate tectonics and geodynamics. In this proposal, we plan to utilize updated techniques of isotropic and anisotropic seismic tomography to jointly invert abundant body-wave travel-time data of local earthquakes and teleseismic events, which were recorded at permanent and portable seismic stations in SE Asia. As a result, we can obtain high-resolution 3-D models of P-wave velocity, S-wave velocity, Poisson’s ratio, and anisotropy of the crust and upper mantle beneath the study region. From these results, we investigate geometries of the subducting slabs and deep channel, magmatic and fluid activities, and mantle convection. Combining the present results with previous findings of multidisciplinary studies, we expect to clarify the mechanism of mantle interactions between the SE Asia ANSS and West Pacific.