Discovery of tempestite in Middle Triassic Tianjingshan Formation in western Sichuan and its paleogeographic significance

Tempestites have been found for the first time in the Middle Triassic Tianjingshan Formation in western Sichuan.The tempestites contain many typical sedimentary structures originated from storm activities,such as scour-infill structure,graded bedding,massive bedding,hummocky cross stratification,sunken cross stratification and flat rudites.The tempestites have 6 types of sedimentary sequences,among them,typeⅠand typeⅡ are distal tempestite,while type Ⅲ,Ⅳ,Ⅴand Ⅵ are proximal tempestite.The wide distribution and differences in regional distribution of tempestites indicate that the sedimentary environment of the western margin of Yangtze Block during Ladinian stage might be a ramp oflowlatitudes where the stormactivities were frequent.The tempestite of Tianjingshan Formation is a newkind ofreservoir in Sichuan Basin.