Tectonic deformation of Jurassic Shiguai coal basin in central Inner Mongolia

Through the analysis of typical structures formed in Shiguai basin on the front of Daqingshan nappe system,it is indicated that in the early of Early Jurassic the NNE-SSE trending extension stress controlled the basin and formed the nearly east-treading fault basin,then the coal-bearing Wudanggou Formation deposited.In the end of Middle Jurassic,Shiguai basin endured the near east-west trending pressure and formed a series of conjugate joints.During the Late Jurassic episode,controlled by the Daqingshan nappe structure,a series of close isoclinal folds and open folds and fault-related folds was formed in the sedimentary blanket.The early Early Jurassic extension would be the result of collapse of the crust thicken during Indosinian orogenic movement,and the late Late Jurassic pressure would be the intraplate response of collision on plate margin.