Re-Os (ICP-MS) DATING OF MARINE OIL SHALE IN THE QIANGTANG BASIN, NORTHERN TIBET, CHINA

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.