华南东部南岭—武夷交汇区中生代构造转换的深部过程与动力学机制研究 ——宽频带密集台阵流动观测的应用

The tectonic transition from east-west to the northeast in southeastern China was a major geological event that occurred in Mesozoic, which is of great significance for the Mesozoic to Cenozoic evolution of South China and continental dynamics. However, the corresponding deep process and dynamic mechanism remain controversial due to the shortage of deep high-resolution data. The intersection area of the Nanling range-Wuyi mountain may save the geological record of this process and could be the ideal place to study the deep dynamic mechanism in southeastern China. Sinoprobe research has found several clues of a weak lithosphere that might be related to this deep process.. This project plans to deploy 60 broadband seismograph stations as a complement to the 40×40 km seismic array of “deep structure probe in South China” thus to cover the intersection area of the Nanling range-Wuyi mountain with a highly dense seismic array. This array will be kept in observation for 2 years. Combining the Sinoprobe data, we plan to construct a three-dimensional velocity structural model that is approximately in a geological mapping scale, by using several seismological methods, such as finite frequency tomography, receiver function imaging, ambient noise tomography, and shear wave splitting analysis. Based on the characters like crustal and upper mantle structure, seismic anisotropy , especially the coupling between the weak lithospheric zone and the shallow tectonics (e.g., Ganjiang fault, Jiangshao fault), as well as the magmatic rock distribution, we can study the deep process and dynamic mechanism related to the tectonic transition of the Nanling-Wuyi belt. Finally, this project is expected to provide deep information for the research into the split of the paleo-Cathaysia block.

从WE向到NE向构造体制的转换是华南东部中生代经历的重大地质事件，对华南大陆中新生代演化和大陆动力学有重要意义。但是由于缺乏较高分辨率的深部资料，其深部过程及动力学机制一直有争议。南岭-武夷山交汇区可能保存了该过程的地质记录，是研究华南东部深部动力学机制的理想场所。Sinoprobe研究已发现可能与该过程有关的岩石圈薄弱带的线索。.本项目拟在“华南深部结构探测”项目40×40 km台阵基础上，再投入60套宽频带地震仪，形成对南岭-武夷山交汇区的密集阵列覆盖，观测2年，利用有限频成像、接收函数、噪声成像和剪切波分裂等地震学方法，结合Sinoprobe资料，构建接近地质填图尺度的三维速度结构模型；依据壳幔结构、各向异性等特征，特别是岩石圈薄弱带与浅部构造（赣江断裂、江绍断裂）、岩浆岩分布的耦合关系，研究南岭—武夷构造转换的深部过程、动力学机制；为华夏古陆块裂离研究提供深部信息。

南岭-武夷山交汇区是研究华南东部中生代构造体制转换深部背景和动力学机制的理想场所。在“华南深部结构探测”项目40×40km台阵基础上，本研究再投入60套宽频带地震仪，形成了对重点关注区域的加密覆盖，观测2年，对采集到的数据和共享来的数据开展了接收函数、有限差分成像等处理分析，构建了地壳上地幔0-700 km的的三维结构模型；依据壳幔结构、波速比等特征，特别是岩石圈薄弱带与浅部构造（赣江断裂、江绍断裂）、岩浆岩分布的耦合关系，认为南岭—武夷中生代构造转换主要受控于特提斯洋闭合，陆陆碰撞和太平洋板块西向俯冲和始新世至今太平洋（菲律宾）板块俯冲转向的地球动力学过程。