The Late Paleozoic Basin System in the Western Part of East Kunlun
东昆仑西段晚古生代盆地系

The western part of the East Kunlun orogenic belt can be divided into three belts,namely,the back-arc basin,the arc belt and the accretion wedge.In the back-arc basin,there are sediments varying from continental shelf to deep basin,and intermediate-acidic volcanic deposits as well as limestone and sandstone.In Late Permian,deposition ended and changed into land.The sedimentary cover of the arc belt is a number of isolated carbonate platforms and intramontane basins.There existed intense volcanic activities,resulting in the formation of such facies of volcanic rocks as subvolcanic facies and explosive facies.The accretion wedge of East Kunlun is very complex in composition.Large quantities of intermediate acidic volcanics were carried into the basin and formed such rocks as continental detritus turbidite,calcium detritus turbidite and silicalite.In Late Paleozoic,the deposition in the western part of East Kunlun was characterized by the asymmetry of sedimentary facies,the alternate distribution of "basin and range",the diversity of sedimentary types,the double or multiple directions of provenance and paleocurrent,the two-layer feature of the sedimentary sequence,and the low maturity of sediments as well as close provenance.The evolution of the western part of East Kulun in Late Paleozoic can be divided into basin expansion stage and arc-continent collision stage.Hence in Late Paleozoic the western part of East Kunlun was a arc-basin system.