北祁连山西段熬油沟蛇绿岩SHRIMP分析结果及其地质意义  

SHRIMP dating of the Aoyougou ophiolite in the west sector of the north Qilian Mountains and its geological significance.

作　　者：张招崇[1] 周美付[2] Paul T ROBINSON 毛景文[4] 杨建民[4] 左国朝 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]香港大学地球科学系 [3]Department of Earth Sciences,Dalhousie University [4]中国地质科学院矿床地质研究所,北京100037 [5]甘肃省地质矿产局地质科学研究所,兰州730000

出　　处：《岩石学报》2001年第2期222-226,共5页Acta Petrologica Sinica

基　　金：国家计委国土司 ( JG947190 2 );国家重点基础研究发展规划项目 ( G19990 432 0 5 )

摘　　要：本文通过对北祁连山西段熬油沟蛇绿岩中辉绿岩岩墙中的锆石 SHRIMP法年龄的测定 ,确定出熬油沟蛇绿岩形成于中元古代早期 (约 1777Ma) ,这是迄今为止我国发现的最古老的蛇绿岩。该年龄测定的结果还暗示了本区在 146 6 Ma和5 0 7Ma各有一次地质事件 ,前者可能代表了中元古代早期的洋盆闭合的下限年龄 ,后者代表一次加里东期区域变质事件 ,并且本区可能还存在未出露的新太古代结晶基底 (2 5 6 1Ma)。The SHRIMP U Pb zircon data of a diabase from the Aoyougou ophiolite in the west sector of north Qilian Mountains are reported in the paper. It shows that the Aoyougou ophiolite was formed in the early middle Proterozoic (about 1777Ma), and proves that it is the earliest ophiolite that has been reported in China. In addition, the dating implies that two geological events occurred about 1466 Ma, and 507 Ma, respectively. The former one probably represents the least closure age of the ocean basin of the early middle Proterozoic whereas the latter one represents the Caledonian regional metamorphism. Moreover, Late Archean crystallized basement (about 2561 Ma) may present in the area although it did not outcrop.

关 键 词：蛇绿岩 中元古代早期 SHRIMP测年 北祁连山 地质事件 锆石 

分 类 号：P588.125[天文地球—岩石学] P597.3[天文地球—地质学]