The newly-discovered paleoweathering crust sediments are developed beneath the continental volcanic rocks, sedimentary-volcaniclastic rocks, and alluvial-diluvial sandstones and conglomerates from the Upper Triassic Nadigangri Formation, and diachronously overlapped upon the Upper Triassic (?) Xiaochaka Formation and its underlying strata in the Qiangtang Basin, indicating a sedimentary gap between the Nadigangri Formation and its underlying strata. The SHRIMP zircon U-Pb isotopic dating implys that the onset of the Mesozoic Qiangtang Basin should traced back to the Late Triassic. The deposition went through the continental to marine sedimentary overlap during the early evolution of the Mesozoic Qiangtang Basin. On the whole, the deposition displays a deepening-upward transgressive sequence, characteristic of a passive marginal rift basin.