A discussion on the provenance and age of Xiangshan Group in Eastern Hexi Corridor

Abstract: The Xiangshan Group is composed of a set of marine clastic rocks with small amounts of limestone and siliceous rocks, which experienced the greenshist facies metamorphism, and is located mainly in the eastern Hexi Corridor. The comparison between the detrital zircon ages (LA-ICP-MS) of the Xiangshan Group and the Miboshan Formation shows that the youngest zircon (451±8) Ma of Miboshan Formation is younger than the youngest (525±3) Ma of the Xiangshan Group, and Xiangshan Group does not contain other young zircons as the Miboshan Formation. Therefore, the age of Xiangshan Group should be younger than (525±3) Ma and older than the Ordovician Miboshan Formation. The Xiangshan Group may be the Middle-Late Cambrian in age. Furthermore, the striking comparison between detrital zircon ages of the Xiangshan Group with the ages of magmatic and/or metamorphic events of southwest Australia, Cathsysia Block, the basement of Alxa Block, the western margin of North China Block, and the North Qilian Orgenic Belt shows that the possibility of Cathsysia Block, the basement of Alxa Block, the western margin of North China Block, and the North Qilian Orgenic Belt as the provenance of Xiangshan Group should be ruled out. Combined with paleocurrent data of the Xiangshan Group, the authods argue that the southwestern Australia might have been the main provenance of the Xiangshan Group.