Provenance analysis of upper triassic series of Liushan basin

The clastic sedimentary structure,composition and structure of the debris of upper triassic in Liushan basin are investigated by means of measured stratigraphic section,thin sections,grain size analysis,X diffraction and cathodoluminescence characteristics of clastic rocks.Then the sediment source area is analyzed.The result indicates that the upper triassic in Liushan basin is a set of near-sourcing sediments,which may mainly come from the intrusive rocks in the Jinningian and variscan,the metamorphic rocks of the mesoproterozoic Kuanping group and the volcanic rocks of the palaeozoic Erlangping group in Qinling orogenic belt.The ancient basement of North China block and the above sedimentary rocks do not supply material for Liushan basin.This proves that Liushan basin may be an isolated basin developed in Qinling orogenic belt during the late triassic.