Abstract:

The Southern Qilian Basin deposits of the continental facies with the development of the detrital rocks in the Upper Triassic Atasi Formation. The lithology and lithofacies characteristics of Triassic sandstone is very similar to Permian sandstone, but the tectonic setting, material composition and the source area of Triassic source rock is different from Permian source rock in Southern Qilian Basin. According to the analysis results of major elements and trace elements of the sandstones,the source rocks of Upper Triassic Atasi Formation belong to an active tectonic setting, mostly like the continental island arc and active continental margin. The material composition of the source rock is mainly the felsic volcanic rock. The source area of the deposition of the Upper Triassic Period in Southern Qilian Basin is most possibly the metamorphic crystalline rock series and granite of the Presinian System and Lower Paleozoic from Middle Qilian integrated with the regional tectonic setting.

Key words: Southern Qilian Basin, Upper Triassic, Atasi Formation, geochemistry, tectonic setting, provenance