西昆仑山前晚新生代磨拉石时代及意义

西昆仑山前柯克亚剖面晚新生代沉积记录了昆仑山乃至整个青藏高原的隆升过程.古地磁研究结果显示,西昆仑山前磨拉石形成于中新世晚期-上新世早中期,反映西昆仑山-青藏高原在中新世晚期有一次快速的隆升过程.孢粉记录结合区域地质资料分析表明,柯克亚剖面上部厚层砾岩的形成时代应为上新世早中期,而整个磨拉石开始沉积的时代应更早,为中新世晚期.沉积记录和气候变化显示了青藏高原在中新世晚期发生了显著的构造隆升事件.

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.