关键词: 鄂尔多斯盆地;石盒子组;物源区;二叠纪

Abstract: he aim of this paper is to discuss the original southern boundary of the Permian Shihezi Formation in the Ordos Basin. Based on field observation and laboratory works, through petrological and provenance analyses, this paper discusses its provenance and tectonic affinity of the Shihezi Formation in southern Ordos Basin and North Qinling. The results suggest that rock lithics of the Shihezi Formation from both areas are similar and is characterized by epimetamorphic rock and granite, with few tectonite; the detrital mode compositions are similar and both are associated with collisional orogenic belt and foreland uplift provenance; In SiO2/Al2O3-K2O/Na2O and K2O/Na2O-SiO2, Zr-Th,La-Th-Sc,and Th-Sc-Zr/10 diagrams, both areas show the same tectonic background. F1-F2 distinguish diagram shows the consistent provenance of these two areas. They also have similar REE distribution patterns. Therefore, metamorphic rock and magmatic rock in Proterozoic of North Qinling as well as the low- grade metamorphic rocks of recycled orogen to its southern area may most probably the potential sources for the Shihezi Formation in southern Ordos Basin and North Qinling. It is inferred that the south border of the Ordos Basin had crossed Luonan tectonic belt and maybe reached to North Qinling.

Key words: Ordos Basin;Shihezi Formation;provenance;Permian