THE AGE OF LATE CENOZOIC MOLASSE IN THE FRONT OF THE WESTERN KUNLUN,XINJIANG AND ITS SIGNIFICANCE

Late Cenozoic sediments in the Kokyar section in the front of the West Kunlun record the uplift process of the Qinghai-Tibet Plateau.Paleomagnetic study shows that the molasse in the front of the West Kunlun formed in the late Miocene to early-mid Pliocene,reflecting that a rapid uplift process took place in the West Kunlun-Qinghai-Tibet Plateau in the late Miocene.Analysis of the sporopollen record and regional geological data indicates that the thick-bedded conglomerate in the upper part of the Kokyar section should be early-middle Pliocene in age,while the deposition of the entire molasse should begin still earlier,i.e.in the late Miocene.The depositional record and climatic change suggest that a prominent tectonic uplift event occurred on the Qinghai-Tibet Plateau in the late Miocene.