Paleogene basin Zircon U-Pb Geochronology and basin record of Xurucuo Area in Tibet

Aimed at exploration of provenance and basin filling records, the authors selected detrital zircons from Rigongla Formation of the Paleogene in the middle part of central Lhasa and conducted LA-ICP-MS detrital zircon U-Pb isotope analysis. The result reveals that Rigongla Formation is a kind of classic rocks which evolved from coarse to thin to coarse, with minor interbedded volcanic rocks. Judging from the sedimentary primary structure and the macroscopic section, its sedimentary environment was fan delta and shallow lake facies and fan delta. The peak age of magmatic origin of detrital zircon is concentrated in the 127-134 Ma age section. Combined with perimeter age, it is held that the provenance was from the early Cretaceous granite of NNW-trending central Lhasa block, and it was in the stage of subduction and collision uplift of the Tibetan Plateau and the stage of convergence and uplift.