地震工程学报2017，Vol.39Issue(1)：168-176,9.DOI:10.3969/j.issn.1000-0844.2017.01.0168
青藏高原东北缘SKS波分裂研究
SKS Wave Splitting of the Northeastern Margin of the Qinghai Tibet Plateau
摘要
Abstract
Based on the teleseismic SKS phase recorded by 43 permanent broadband stations in Gansu Province in the northeastern margin of the Qinghai-Tibetan plateau,this study obtains the splitting parameters of the fast-wave polarization direction and delay times at each station u-sing the minimum energy and rotation-correlation methods.The results can be summarized as fol-lows.In the southeastern region of Tarim Basin,the fast-wave polarization sites exists obvious angle with the strike of regional faults,and coincides with the subduction direction from Tarim Basin to Qaidam Basin.This result reveals that the upper mantle deformation is mainly affected by ancient tectonic movement.The anisotropy observed may be considered "fossil" anisotropy. Because of crust-mantle delamination,decoupling between the crust and mantle occurs in this ar-ea.In the Qilian-Hexi Corridor region,fast-wave polarization shows a NW-SE trend,consistent with the strike direction of the main faults in this region.Comparison of the fast-wave directionwith the direction of lithospheric extension and GPS-observed velocity reveal that the deformation model of the crust and upper mantle may be vertically coherent deformation.In the northern fringe fault of the western segment of the Qinling mountains,slow-wave time delays exert signif-icant anisotropy in the vicinity.This phenomenon could indicate upper mantle deformation,which is caused by both deformation of the lithosphere and flow of the asthenosphere.In the Ordos block,the fast-wave direction shows a NW-SE trend,which suggests that the movement of deep material exists motion of flow around the Tibetan plateau.Collision between plates causes thick-ening and uplifting of the western China crust and eastward extrusion of material in the north-eastern margin of the Qinghai-Tibetan plateau.Different regional stations present different lev-els of anisotropy in the northeastern margin of the Qinghai - Tibetan plateau,which further proves the complexity of tectonic deformation in its northeastern margin.According to the split-ting parameters of SKS waves,the anisotropic characteristics of the study region are analyzed to investigate dynamic processes in the area.关键词
青藏高原东北缘/SKS波分裂/各向异性/上地幔Key words
northeastern margin of the Qinghai-Tibet Plateau/SKS wave splitting/anisotropy/upper mantle分类
天文与地球科学引用本文复制引用
潘宇航,蒲举,程建武,陈继锋..青藏高原东北缘SKS波分裂研究[J].地震工程学报,2017,39(1):168-176,9.基金项目
国家自然科学基金项目(41674046、41440030) （41674046、41440030）
中国地震局科技星火计划(XH15042) （XH15042）
