基于横波分裂方法的海南地幔柱研究

利用横波分裂方法,对北京大学、南方科技大学及桂林理工大学在广东和广西布设的宽频带流动台阵以及国家地震台网在广东、广西和海南的固定台站记录的XKS震相进行计算,得到海南及邻近地区的上地幔各向异性参数,分裂延迟时间在0.35～1.90s之间.综合研究区域内前人发表的和本文的横波分裂结果,认为自新生代以来,伴随东部太平洋板块...

Study of Hainan Mantle Plume Based on Shear Wave Splitting Method

The authors use the shear wave splitting method to calculate the XKS seismic phases recorded by the temporary broadband seismic stations of Peking University, Southern University of Science and Technology and Guilin University of Technology in Guangdong and Guangxi Provinces, and the fixed stations of China Earthquake Administration in Guangdong, Guangxi and Hainan Provinces. The authors obtain the anisotropy parameters of the upper mantle in Hainan and its adjacent areas, and the delay time is between 0.35 and 1.90 s. Based on the previous shear wave splitting results around the research region, the authors believe that with the retreat of the subduction zone of eastern Pacific plate, the asthenosphere material in the west flows eastward to fill, making the olivine lattice of the upper mantle aligned along the E-W direction in most areas of central and northern Guangdong and Guangxi. Because the continental lithosphere at the coastline is thinning rapidly, the splitting results in Guangdong coastal areas are mostly NE-SW direction, parallel to the coastline. In particular, there are several NULL stations in the coastal areas near Hainan Island, and the splitting results in the northeast corner of Hainan Island are very disorderly, with small δt. These observations support that Hainan plume may exist on the southeast of Leizhou Peninsula, which is centered at 20.5°N and 111.5°E.