西昆仑山北部早古生代构造－岩浆带的发现

A DISCOVERY OF AN EARLY PALEOZOIC TECTONOMAGMATIC BELT IN THE NORTHERN PART OF WEST KUNLUN MOUNTAINS

１９８７年以来，先后做了４条横穿昆仑山的综合路线地质调查。它们是：中－巴公路沿线；新－藏公路沿线；于田县普鲁村－苏巴什－硫磺达坂路线；青海茫崖镇－祁曼塔格路线。在西昆仑山北部的调查区内，都有钙－碱性的深成岩体出露。通过对这些岩体系统地做Ｕ－Ｐｂ、Ａｒ－Ａｒ及Ｒｂ－Ｓｒ定年研究，发现它们具有早古生代年龄（３８４—４８０Ｍａ），延伸上千公里，形成于活动大陆边缘或碰撞后的构造环境，常与属于蛇绿岩套的组分相伴生。这充分说明在青藏高原内部存在一条新发现的缝合带。

Since 1987, totally four integrated geological investigation profiles across the West Kunlun Mountains were performed. They are: (1)Profile along the Sino-Pakistan highway (from Kashigar to Kunjirap Pass); (2)Profile along the XinjiangXizang highway .(from Yecheng to Shiquanhe); (3) Pulu Village, Yutian CountySubaxi-Liuhuang Pass profile, and(4) Mangnai Town, Qinghai-Qimantaga-Muzhtaga peak profile. In the investigation region, in the northern part of the West Kunlun Mountains calc-alkaline plutonic rocks are exposed. Systematical geochronological studies of the plutonic rocks have been done, in the paper 5 U-Pb dating on the zircons,3 Ar-Ar dating on the honblende and biotites and 5 Rb-Sr dating on the wholerocks and minerals from the plutons are reported. These results enabled us to find an early Paleozoic (384-480Ma) tectono-magmatic belt, extending for a thousandof kilometers. It was formed on an active continental margin or in a postcollisional tectonis envionment, and is accompanied with a complex belonging to ophiolite suit in Kudi, Subaxi and Oy ag area. It is a newly found and defined suture zonein the interior of the Qinghai-Xizang Plateau.