Sediment Provenance Analysis and Its Tectonic Significance in the Foreland Basin of the Ordos Southwestern Margin

Key words: 
• foreland basin /
• dispersal style /
• the Qm FLt triangular diagram

Abstract: It is effective to determine thrust events of provenance, tectonic setting and provenance strata cor re-sponding to basin sediments according to the clast dispersal style and the components of sediments inforeland basins. Test and study on the Upper Triassic stratigraphic section of the Ankou region in thesouthwestern margin of Ordos show that the provenanc es of stratigraphy are a set of meta lastics andmeta}olcanics which are Chenjiahe Formation(O₃ch)and Huluhe Formation(Z- O₂hl)〔ontributed inteh eastern Qilian fold-thrust belt. The provenance of the Upper Jurassic conglomerate in the south-western margin is Longshan Formation(Pt₂ln)·The dispersal style of the Upper Triassic is the blended clast composition, and thedispersal style of the both of the Upper Triassic and the Upper Jurassic is theinverted dust composition which is the sedimentary response to two times of large thrusting. The analy-sis on the QmFLt triangular diagram representing the sandstone components of the Upper Triassic in theAnkou region shows that the Late Triassic basin in the southwestern margin of Ordos is a foreland basinlocated in the foreland of a collision orogen and the provenance is the fold-thrust massif of the recycledo rogen which is the eastern Qilian orogen.