西昆仑-喀喇昆仑地区钾质碱性岩Ar-Ar年龄——以羊湖、昝坎和苦子干岩体为例

Ar-Ar DATING OF POTASSIC ALKALI-ROCKS IN THE WESTERN KUNLUN-KALAKORUM MOUNTAINS——Example for the rocks of Yanghu,Zankan and Kuzigan

位于西藏西北部和新疆西南部中间地带的西昆仑-喀喇昆仑山地区的羊湖、昝坎和苦子干火山岩岩体是哀牢山-金沙江新生代钾质碱性岩浆岩带的西延部分,A r-A r测年结果为18 M a^12 M a,结合该地区岩体的岩石化学成分研究,表明哀牢山-金沙江新生代钾质碱性岩浆岩带的岩浆作用东早西晚,始于始新世中期(41 M a)到更新世(0.3 M a^0.07 M a),岩浆作用时间长达40 M a。这一现象与印度、欧亚两大陆碰撞时间在50 M a^45M a至今是一致的,暗示其成因与印度、欧亚两大陆碰撞有内在的联系。

Volcanic rocks occurred at Yanghu,Qiankan and kuzigan in the center of the northwestern Tibet and the southwestern Xinjiang,which is the western part of Ailaoshang-Jinshajiang Cenozoic potassic alkali magmatic rock zone. The Ar-Ar dating of the rocks shows the ages of 17 Ma,12 Ma and 18 Ma. Study on the chemical compositions of these rocks indicates that the time of magmatic activity in the Ailaoshang-Jinshajiang Cenozoic potassic alkali magmatic rock zone becomes younger gradually from east to west. The magmatic event starts from the middle of the Eocene to the Pleistocene. This phenomena reveals that there is some inherent relationship of the collision between the India slab and Europe-Asia slab.