Abstract:The deposition age of Dingqinghu Formation in the Lunpola Basin is of great importance to study the paleo-elevation and climate of the central Tibetan Plateau. While, due to a lack of absolute age of the Dingqinghu Formation in the Lunpori Basin, weather the Uppermost part of the Formation contain Miocene deposit is still controversial. Two tuff layers in the Lower to Middle Dingqinghu Formation were found during the geological survey in the Ejiazu area of the Lunpola Basin, and LA-ICP-MS zircon U-Pb dating from the tuffs from Middle and Upper part of the Ejiazu profile yielded ages of 24.05±0.24Ma (MSWD=1.07, n=24) and 22.64±0.33Ma (MSWD=0.45, n=17), respectively, with the deposition age of Late Oligocene and Early Miocene, respectively. According to the new zircon U-Pb age and former researches, the clasticSrockSstrata in the Ejiazu profile was Dingqinghu Formation rather than Niubao Formation, and the deposition age of the Dingqinghu Formation is Oligocene to Middle Miocene. Using sedimentation rate and sedimentation thickness of the Dingqinghu Formation, the whole depositon of Dingqinghu Formation was estimates to last about 21 to 23 Ma, and the top of the Dingqinghu Foramtion was extrapolated to 11~13 Ma. Therefore, the clastic strata were deposited continually until at least the Middle Miocene, which was much later than the previous estimates paleo-elevation and climate of the central Tibetan Plateau since the Late Eocene to Oligocene. The recent discovered fossil mammals, climbing perch and palms plants and advanced palynological paleoaltimetry collectively demonstrate that the paleo-elevation of the Lunpola Basin was lower than ~2500-3000m. Hence, during the Late Oligocene to Middle Miocene time, the warm and humid paleoclimate prevail in this area was probably influenced by the airflow from the India Ocean penetrating into the central Tibetan Plateau, and this Indian monsoon prevailed in the Lunpola Basin at the latest in the Middle Miocene, which led to the diversity of organism in the Tibetan Plateau.