留山盆地上三叠统物源区分析

Provenance analysis of upper triassic series of Liushan basin

通过实测地层剖面,薄片观察,粒度分析,X衍射和阴极发光特征分析,对留山盆地上三叠统碎屑岩的沉积构造、碎屑成分和结构等进行了详细的研究,进而对沉积物源区进行了分析.结果表明,留山盆地上三叠统是一套近源沉积,沉积物质主要来源于秦岭造山带的晋宁期-华力西期侵入岩、中元古界宽坪群变质岩和古生界二郎坪群火山岩,而华北陆块古老基底及其上部沉积岩未对盆地提供物源,佐证了留山盆地为一个孤立盆地.

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.