大巴山侏罗纪叠加褶皱与侏罗纪前陆

Jurassic Superposed Folding and Jurassic Foreland in the Daba Mountain, Central China

大巴山是NWW_SEE走向的中央造山带中惟一的向南凸出大型弧型褶皱带,与秦岭—大别造山带的构造特征明显不协调。研究表明,大巴山弧型构造卷入了侏罗纪地层,因此不属于三叠纪中央造山带。秦岭、大别山和大巴山最新的证据证实侏罗纪曾经发生陆内俯冲作用,大巴山是侏罗纪陆内造山作用的产物。大巴山西侧为典型的叠加褶皱变形样式,三叠纪近东西向褶皱叠加上近南北向褶皱构成横跨型干涉变形图像。由此,确立了侏罗纪复合前陆的存在,证明中国东部甚至亚洲东部侏罗纪陆内造山的广泛性,晚侏罗世的“燕山运动”是波及亚洲中东部的重要构造事件。

The Daba Mountain, a unique convex-southern bow-like folding belt in NWW-SEE striking Qinling Orogen, is obviously uncoordinated with the Qinling orogenic belt in tectonic characteristics. Researches indicate that the Dabashan bow-like folding belt was formed during late Jurassic and superposed on Triassic folds, and hence it does not belong to Qinling Triassic Orogen. The new evidence reveals that the intra-continent subduction in Dabieshan, Dabashan and other places in central China occurred in Late Jurassic. TheⅠtype superposed folding and deformation was developed on the western side of Daba Mountain with a crossing interference style, in which nearly NS-striking Jurassic folds were superposed on nearly EW-striking Triassic folds. On such a basis, Jurassic foreland can be reconstructed along the bow-like folding belt in the Daba Mountain. The authors believe that the Jurassic intra-continent orogenic movement was an extensive event in eastern China, even in eastern Asia.