青海可可西里湖地区新生代两期火山岩

TWO PERIODS OF CENOZIC VOLCANIC ROCKS FROM HOH XIL LAKE AREA,QINGHAI

青海可可西里湖地区新生代火山活动表现强烈,通过野外地质填图,结合岩石学、岩石化学、同位素测年等方面的详细研究,确定发育渐新世-中新世查保玛旋回及晚中新世-早更新世湖东梁旋回两期火山岩。渐新世-中新世火山岩以钾玄岩系列为主,部分为高钾碱性系列,火山活动强烈出露面积大而广泛。晚中新世-早更新世火山岩为高钾钙碱性系列,发育于研究区北部,分布范围和面积均较小。

According to the achievement of regional geological mapping and the Ar-Ar isotopic age,Cenozic volcanic rocks of two periods were found in Hoh Xil Lake area,Qinghai. Their geological time are Oligocene-Miocene and late Miocene-Pleistocene. Oligocene-Miocene volcanic rocks are shoshonite,late Miocene-Pleistocene volcanic rocks are High-k calc alkaline. The study of volcanic rocks provides not only detail of volcanic activity,but also the upper limit of Cenozic continental redbeds.