Deformational Process from Thick-skinned to Thin-skinned Thrust in Xuefeng Mountain,South China:Evidence from Sangzhi-Anhua Tectonic Section
Deformational Process from Thick-skinned to Thin-skinned Thrust in Xuefeng Mountain,South China:Evidence from Sangzhi-Anhua Tectonic Section
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发表时间：
2011
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通讯作者：
Zhang Wei-cheng
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作者：
Zhang Wei-cheng
雪峰山及其西北部地区的大涌断层将厚皮逆冲断层与薄皮逆冲断层分隔开来，对华南中生代构造过程产生了不同的解释，因此大涌断层的构造样式和成因是认识雪峰山构造的关键。本文应用沿着桑植-安化构造剖面的地震剖面和大地电磁测深资料进行了解释，结果表明，厚层-薄层早志留世-中泥盆世板溪群逆冲于下古生界之上形成皮状逆冲断层，中三叠世-侏罗纪厚皮逆冲断层的复活使大涌断裂沿着板溪群软弱层向南东方向形成倾角较小的拆离断层，同时叠加了老的厚皮逆冲断层，后期变形又形成了北西向逆冲断层、与断层有关的人字形向斜和平坡逆冲断层，称之为薄皮逆冲断层，因此，认为古生代发育的原厚皮逆冲断层与雪峰山的拆离断层叠加，中生代北西向逆冲断层又在其北西侧产生薄皮逆冲断层。
Thick-skinned thrust separating from thin-skinned thrust by the Dayong fault in Xuefeng Mountain and area on its northwest,brings variable interpretations of Mesozoic tectonic process in South China,and thus the structural style and origin of the Dayong fault are the keys to well understand tectonics of Xuefeng Mountain.Field investigation,interpretation of the data of seismic section and magnetotelluric sounding along Sangzhi-Anhua tectonic section are applied in this paper.The results indicate that the thick-skinned thrust was produced by thrusting the Banxi Group over the Lower Paleozoic in Early Silurian to Middle Devonian.The re-activation of the thick-skinned thrust during Middle Triassic to Jurassic turned Dayong fault into a detachment fault along weak layer of Banxi Group with tiny dip angle towards southeast,which overprinted the old thick-skinned thrust in the meantime.This late deformation also resulted in a NW-ward overthrusting,fault-related chevron syncline and flat-ramp thrust fault,known as the thin-skinned thrust.Therefore,we conclude that the original thick-skinned thrust developed in Paleozoic era was overprinted,with a detachment fault in Xuefeng Mountain,by the NW-ward thrust in Mesozoic era which also produced the thin-skinned thrust on its northwest side.