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A suite of sedimentary-volcaniclastic rocks intercalated with the volcanic rocks unconformably overlies the Triassic Xiaochaka Formation in the Woruo Mountain region, Qiangtang Basin, northern Tibet. The vitric tuff from the base of these strata gives a SHRIMP zircon U-Pb age of 216 ± 4.5 Ma, which represents the age of the Late Triassic volcanic-sedimentary events in the Woruo Mountain region, and is consistent with that of the formation of the volcanic rocks from the Nadi Kangri Formation in the Nadigangri-Shishui River zone. There is a striking similarity in geochemical signatures of the volcanic rocks from the Woruo Mountain region and its adjacent Nadigangri-Shishui River zone, indicating that all the volcanic rocks from the Qiangtang region might have the same magmatic source and similar tectonic setting during the Late Triassic. The proper recognition of the Late Triassic large-scale volcanic eruption and volcanic-sedimentary events has important implications for the interpretation of the Late Triassic biotic extinction, climatic changes and regressive events in the eastern Tethyan domain, as well as the understanding of the initiation and nature, and sedimentary features of the Qiangtang Basin during the Late Triassic-Jurassic.

Marine oil shale from the Shenglihe oil shale section in the Qiangtang basin, northern Tibet, China, was dated by the Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron was obtained giving an age of 101±24 Ma with an initial 187 Os/ 188 Os ratio of 1.84±0.11(n = 11, MSWD = 3.5). The Re-Os age agrees with the geological age derived from biostratigraphic data, indicating the great potential of the Re-Os method for dating the marine oil shale. Our new data (Bilong Co oil shale) also show that the samples must derive from the same layer of oil shales to determine an accurate and precise depositional age for the marine oil shale with the 187 Re- 187 Os radioisotope system.