阿尼玛卿蛇绿岩带花岗—英云闪长岩锆石U—Pb同位素定年及大地构造意义

ZIRCON U-Pb AGE OF GRANODIORITE-TONALITE IN THE A'NYEMAQEN OPHIOLITIC BELT AND ITS TECTONIC SIGNIFICANCE

对阿尼玛卿蛇绿岩带布青山段花岗—英云闪长岩进行的锆石 U— Pb同位素定年及岩石化学研究表明 ,该岩体锆石 U— Pb年龄为 40 2± 2 4 Ma,归属加里东末期 ,并非二叠 -三叠纪同造山岩浆活动的产物 ;岩石属钙碱系列 ,具岛弧花岗岩特征 ,暗示着本区在早古生代发生过洋壳俯冲及岛弧岩浆活动事件 ,并为本区早古生代蛇绿岩的存在提供了佐证。

Zircon U\|Pb age determination and lithochemistry research of the granodiorite\|tonalite intruded in Buqinshan ophiolitic melange,the western sector of A'nyemaqen Ophiolitic Belt, are first done and reported in this paper. Its zircon U\|Pb age is 402±24Ma and belongs to Late Caledoian. The rock belongs to calc\|alkaline series, has the features of island\|arc granite,which hints that oceanic crust subduction and island\|arc magmatism event occurred in the area in Early Paleozoic. The research achievement is of great significance to re\|understand the tectonic framework and evolution of the area,even the Central Orogenic Belt.