摘要
本文对青藏高原中部Hi-CLIMB(Himalayan-Tibetan Continental Lithosphere Durmg Mountain Building)宽频带数字台站探测剖面资料进行处理,用转换函数模拟退火算法得到了83个台站下方S波速度结构,转化为二维速度结构剖面,并与接收函数偏移成像结果进行了对比.反演结果可清晰显示出工作区地壳内S波速度界面和不连续的莫霍面.研究表明,从N29.4°至N31.5°地壳平均厚度为75 km;在N 32°以北地壳平均厚度为65 km.壳内界面在N31.5°以南向北倾斜,而在其北部向南倾斜.在雅鲁藏布江缝合带和班公-怒江缝合带附近地壳具有明显低速区.这一复杂结构反应了该区域内部强烈挤压变形与物质交换,为进一步研究岩石圈变形与构造演化提供了新的地球物理学证据.
Based on the detection profiles of Hi-CLIMB broadband digital stations in the central Tibetan Plateau,the S-wave velocity structures beneath 83 teleseismic stations(Hi-CLIMB experiment data) are obtained by using the transform function method.The detection profiles are transformed into two-dimensional velocity structure profiles,and then compared with the CCP results.The inversion results clearly show the S-wave velocity structure in crust and a velocity jump across the Moho discontinuity in the region.The results reveal that the average thickness of the crust is 75 km from N29.4°to N31.5°and 65 km northward from N32°.The interfaces dip northward in the south of N31.5°,but in the north the structure is exactly inverse.We also find a marked slow-velocity zone in crust beneath YZS and BNS.This complex structure suggests that there exist strong compressional deformation and material exchange in the region.The results presented here provide new evidence for further study of hthospheric deformation and tectonic evolution around the middle of Tibetan plateau.