Regional variations in crustal thickness and Vp/Vs ratio beneath the central–western North China Craton and adjacent regions
Regional variations in crustal thickness and Vp/Vs ratio beneath the central–western North China Craton and adjacent regions
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DOI：
10.1002/gj.2473
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发表时间：
2013-09
影响因子：
1.8
通讯作者：
Zigen Wei;Ling Chen;Bingyu Wang
中科院分区：
文献类型：
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作者：
Zigen Wei;Ling Chen;Bingyu Wang
利用华北中西部及邻区363个宽带台站的地震波形记录，应用接收函数的H-κ叠加方法，估算了华北中西部及邻区的地壳厚度（H）和平均Vp/Vs比值（κ）。结果表明，除新生代裂谷和NCC中部南缘变薄外，H从NCC中部最东缘的约30 km向西逐渐增厚，到青藏高原东北缘的>60 km。κ值变化复杂，在裂谷、中部NCC南缘和构造边界带局部出现高异常或低异常。鄂尔多斯上地幔密度低，南北差异明显，为典型的地幔型地壳。鄂尔多斯西南缘地壳增厚、κ值变化复杂，可能与古生代祁连地块的形成和青藏高原晚期隆升有关。在新生代裂谷及其附近观察到地壳变薄和局部高κ，这表明复杂的地壳变化可能是由连续的热构造事件在先前存在的薄弱地带反复活化引起的。华北克拉通南缘地壳厚度较薄，κ值较低，反映了华北克拉通与扬子陆块碰撞后的地壳变形，特别是下地壳的拆沉作用。版权所有© 2012约翰威利父子有限公司.
Using teleseismic waveform records from 363 broadband stations, we applied H–κ stacking of receiver functions to estimate crustal thickness (H) and average Vp/Vs ratio (κ) in the central and western North China Craton (NCC) and adjacent regions. Our results show that, except for thinning in the Cenozoic rifts and southern edge of the central NCC, H gradually thickens westward from ~30 km at the easternmost edge of the central NCC to >60 km near the northeastern margin of the Tibetan Plateau. κ exhibits complex variations, with locally high or low anomalies in the rifts, at the southern edge of the central NCC and at tectonic boundary zones. Low‐density uppermost mantle and distinct N–S differences are observed in the Ordos, suggesting typical cratonic crust. Thickened crust and complex variations in κ at the southwestern boundary of the Ordos may be related to the formation of the Palaeozoic Qilian Block and late uplift of the Tibetan Plateau. Thinned crust and locally high κ are observed in and near the Cenozoic rifts, suggesting complex crustal modifications that may have been caused by repeated reactivation at pre‐existing weak zones by successive thermal‐tectonic events. Thin crust and low κ are found at the southern edge of the central NCC, suggesting crustal modifications such as delamination, especially in the lower crust, which may be related to collision of the NCC and Yangtze Block. Copyright © 2012 John Wiley & Sons, Ltd.