Detrital zircon U-Pb age of the Duoni Formation sandstone in Dongcuo area, Tibet, and its geological significance

In this paper, the authors conducted some researches on U-Pb geochronology of detrital zircon of the Duoni Formation in Dongcuo area, Tibet. The grain diameter of detrital zircon is 50~180μm. The Th/U ratio is high. The Th/U ratio of 51 zircon samples is greater than 0.4, with the typical value being 0.64. So the magmatic zircon is dominant. The distribution of U-Pb age of zircon is 3261Ma, 2739~2335Ma, 1880~1750Ma, 1006~657Ma, 577~510Ma, 456~409Ma and 252~202Ma. The oldest detrital zircon age is 3261Ma. The provenance of the sediments contained residues of the earth's crust in Archean.The U-Pb age of zircon corresponds to the tectonic event of Qiangtang. So the provenance of Lower Cretaceous Formation in Dongcuo area should be Qiangtang block.