基于三重震相波形拟合方法研究华北克拉通上地幔速度结构

The North China Craton(NCC),which is different from the other Cratons, experienced significant magmatism in the Mesozoic and Cenozoic. Based on the geological and geophysical studies, the researchers deeply discussed the tectonic evolution and destruction mechanism of the NCC. However, there were debates on the detailed spatial distribution of lithospheric thinning and the destruction mechanism. Since the structure of the upper mantle is an important source of information for understanding reactivation and destruction mechanism of the NCC, it is imperative to obtain reliable and high-resolution structure of the upper mantle. In this study, we will study the triplicate waveform modeling and use this method to study the velocity structure of the upper mantle(including the lithosphere, asthenosphere and transition zone). Based on the triplicate waveform modeling, we will present the velocity structure of the upper mantle beneath the NCC using a dense seismic array that located in the study area and its adjacent area to provide more geophysical evidence to study the destruction mechanism of the NCC.

与世界其他典型克拉通不同，华北克拉通在中、新生代期间经历了强烈的岩浆活动。基于地质与地球物理调查，研究人员对克拉通的构造演化过程与破坏机制进行了深入的讨论，然而关于华北克拉通的破坏范围与破坏机制仍存在激烈争论。可靠的上地幔结构是认识和理解华北克拉通破坏的重要地球物理资料，因此进行获取华北克拉通可靠的和高分辨率的上地幔结构的研究就显得极为迫切，本申请拟进行三重震相波形拟合方法研究，使其能够用于上地幔(包括岩石圈、软流圈及上地幔过渡带)速度结构的研究。基于三重震相波形拟合方法，利用布设在研究区及其邻近地区的台站数据来获取更为精确的华北克拉通上地幔速度结构，为研究华北克拉通的破坏机制研究提供更为充分的深部地球物理学依据。

目前关于华北克拉通的岩石圈减薄范围和减薄机制仍存在争论，获取可靠的上地幔结构对认识和理解华北克拉通的减薄具有重要作用。通过进行三重震相波形理论方法研究，我们测试了不同速度模型下三重震相的特征，并验证了此方法的可靠性。接下来将此方法应用于华北克拉通及中国地区的上地幔速度结构研究中，获取了可靠的上地幔速度结构。最后通过结合其他地球物理方法获取的研究区的上地幔结构，对华北克拉通的岩石圈减薄机制进行了探讨，推测华北克拉通是由于太平洋板块俯冲引起的地幔流导致其发生了拆沉，从而引起了华北克拉通的岩石圈减薄。