Mantle anisotropy across the southwestern boundary of the Ordos block, North China
Mantle anisotropy across the southwestern boundary of the Ordos block, North China
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DOI：
10.1007/s11589-010-0754-2
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发表时间：
2010-12
影响因子：
1.2
通讯作者：
Yongzhen Tang;Yongshun John Chen;Yuanyuan V. Fu;Haiyang Wang;Shiyong Zhou;E. Sandvol;J. Ning;Yongge Feng;Mian Liu
中科院分区：
文献类型：
--
作者：
Yongzhen Tang;Yongshun John Chen;Yuanyuan V. Fu;Haiyang Wang;Shiyong Zhou;E. Sandvol;J. Ning;Yongge Feng;Mian Liu
2005年9月至2006年8月，北京大学在渭河地堑西部部署了由15台便携式宽带地震仪组成的线性阵，2007年至2008年在渭河地堑西南边界部署了由14台便携式宽带地震仪组成的二维地震阵（鄂尔多斯西南阵）。对这些台站的SKS和SKKS相剪切波分裂分析表明，在鄂尔多斯地块西南缘，快速方向为~ 110°，平均延迟时间为0.9 s。
Located at the northeastern margin of the Tibetan plateau, the Ordos block is a stable tectonic unit in North China. With its active boundary fault zones, the Ordos block played an important role in the eastward extrusion mechanism of the Tibetan plateau. Peking University deployed a linear array of 15 portable broadband seismometers across the western Weihe graben during September 2005 to August 2006 and later a 2-D seismic array (Southwest Ordos Array) of 14 portable broadband seismometers during 2007–2008 at its southwestern boundary. Analyses of shear wave splitting of SKS and SKKS phases at these stations show that the fast directions trend ∼110° with an average delay time of 0.9 s in the southwestern margin of the Ordos block. The agreement between the lithosphere deformation indicated by GPS data and Quaternary fault slip-rate observations and the mantle flow represented by shear wave splitting implies that accordant deformation patterns from lithosphere to asthenosphere in relation to the eastward extrusion of the Tibetan plateau could extend at least to 200 km depth. Spatial distribution of splitting polarization directions indicates that the mantle flow driven by the Tibetan plateau is blocked by the Ordos block and locally restricted in a narrow channel along the Qinling-Dabie fault zones between the Ordos block and Sichuan basin.