华南与南海北部深部构造特征综合地球物理研究

The integrated research on the deep structure of the South China and the northern South China Sea plays an important role in the study of the geology evolution of the continental south China, the formation and evolution of the South China Sea, and the marine-continental interactions. This application proposed the deep structure study of the south China and the northern South China Sea based on the new onshore-offshore geophysical survey data and the high resolution gravity and magentic data. We develop the onshore-offshore seismic data processing and inversion technique to get the detail crustal sturcture of transitional zone of the land and the sea; develop the 3D constrained gravity and magnetic inversion method to study the crustal structure such as Moho depth, basements, faults system and igneous rocks. Combined with the tomography and the integrated gravity and magnetic inversion of classical profiles, the 3D structural frame of the study region will be established. The integrated geology and geophysical study assists the further analysis combined with the regional tectonic evolution. It will compare the deep structure characters, the tectonic properties and the geodynamic background of the south China and the northern South China Sea, and discuss the tectonic relationship and interaction between the land and marine tectonic units. It will contribute to understand the regional tectonic background and the geodynamic mechanics of the evolution of the south China block and the South China Sea. And it will provide geophysical evidences to solve the scientific problems related with the geology of the south China block and the South China Sea.

华南与南海北部深部结构的一体化研究对深化认识华南大陆地质演化历史、南海形成演化机制以及海陆构造的相互作用具有重要意义。本申请以近年来海陆联测地震调查新数据和高精度重、磁数据为基础，开展华南与南海北部地区深部结构研究。发展海陆联测地震数据处理与反演技术，研究海陆结合带二维精细地壳结构；发展三维重磁约束反演技术，研究莫霍面、基底、断裂与火山岩等深部结构；结合层析成像、典型剖面重磁综合反演建立岩石圈和地壳的三维构造格架。结合区域构造演化，开展综合地质地球物理解释，对比分析华南大陆与南海北部深部结构特征、构造属性及动力学背景，探讨海陆构造关系及其相互作用，深化理解华南与南海构造演化的区域背景及深部动力学机制，为认识华南及南海形成演化的重大科学问题提供地球物理依据。

本项目研究以华南和南海北部深部构造特征为目标，以重力异常、磁力异常为主要数据，结合该地区深地震测深、海底地震探测等开展综合研究，获得了研究区岩石圈有效弹性厚度、莫霍面结构、基底结构、居里面分布及断裂体系等深部结构特征，并通过典型剖面反演开展壳内精细结构研究。深部结构研究成果与地震分布、热流分布等综合分析华南陆块与南海海域构造演化背景与动力学机制，为认识海陆构造差异及相互作用奠定了基础。在以上综合地球物理研究中还发展了多界面重力反演、重力与大地水准面联合反演、海底地震仪数据去噪与处理等多项地球物理技术，为本项研究提供了坚实的技术支撑。