贺西地区晚古生代早中期同沉积断层的发现及其意义

贺西地区处于北祁连加里东褶皱带、阿拉善地块与鄂尔多斯地块的交汇处,该区晚古生代早中期处于早古生代洋盆体制与中生代陆内盆地发育期的转换时期,其盆地性质及成因争议颇多。在贺兰山地区工作中,作者发现晚泥盆世、早石炭世同沉积断层,并详细追踪了上泥盆统、下石炭统与上下地层的接触关系;结合野外相关地质现象及前人的区域地质研究成果,对贺西地区晚古生代早期盆地的性质及其成因进行了讨论,认为该期盆地既非碰撞裂谷,也非前陆盆地,而是造山后伸展型上叠盆地,同时认为该伸展盆地的形成与古特提斯洋打开呈现同步性,具有一定的区域地质意义。

Discovery of late-Paleozoic syndepositional faults in Hexi area

The Hexi area is located at the tectonic convergence of the north Qilian Caledonian orogen,Alex block and Ordos block where was the transitional period between the early Paleozoic oceanic stage and the Mesozoic continental basin developing stage in the mid-late Paleozoic age.The explanations proposed for the formation mechanism of the mid-late Paleozoic basins are varied.During the exploration work in this area the authors discovered syndepositional faults in the late Devonian and early Carboniferous strata and researched their contact relations.On the basis of the field works combining with previous studies,the authors discussed the characters and formation mechanisms of the mid-late Paleozoic basins in Hexi area.The results indicated that the basins are neither foreland basins nor impactogen,but extensional superimposed basins caused by the detachment of the north Qilian Caledonian orogenic belt,and the basin formation would be simultaneously with the stage of the Paleo-tethys.