Provenance Analysis of the Upper Triassic Flysch in Renbu Area,Southern Tibet

The sandstone clastic composition,paleocurrent,trace element and rare earth clement are combined to analyze the provenance of the Upper Triassic Langjiexue Group and the Nieru Formation in Renbu area,southern Tibet.Results of the clastic composition and geochemistry indicate that most of the clastic materials were derived from the recycled orogenic belt;Some of them were from the mixed area before the orogeny;Few was from the continental basement and recorded continental margin arc process prior to the orogeny.It is verified that parent rocks came from the recycled sediments of the orogen and post-Archean.Paleocurrent measurement shows that the Langjiexue Group and the Nieru Formation were probably sourced from the North.The former was from the northeast,but the latter was from the northwest.The latter is closer to the source region than the former.These are consistent with the present distribution of strata.These results suggest that the upper Triassic flysch were probably sourced from the north or even the Lhasa Block.