北祁连山西段巴个峡-黑大坂一带几个花岗闪长岩体的侵入时代讨论—─兼论古阿尔金断裂活动时间  

A Discussion on Intrusion Epochs of Granodiorites along the Bagexia-Heidaban Zone in the Western Part of the North Qilian Mountains

作　　者：宋忠宝[1] 任有祥[1] 李智佩[1] 杨建国[1] 

机构地区：[1]西安地质矿产研究所

出　　处：《地球学报》2004年第2期205-208,共4页Acta Geoscientica Sinica

基　　金：原地质矿产部"九五"科技攻关项目"北祁连山西段黄铁矿型铜多金属矿床与构造蚀变岩型金矿床成矿模式及找矿预测研究 (95 0 2 0 0 4 0 3 )"资助

摘　　要：北祁连山西段巴个峡 黑大坂一带分布一套花岗闪长岩 ,前人未做同位素年龄测定 ,根据岩体与围岩的接触关系确定为华力西晚期 ;笔者根据单颗粒锆石U Pb年龄测定确定了这套岩石的侵入年龄为 4 81.6± 3.3Ma,为加里东晚期。应属早中奥陶世 ,并对其进行了讨论 ;进而指出阿尔金断裂的形成时代可能大于 4 81.6± 3.3Ma,且进行了论证。其地质意义有两点 :①阿尔金断裂带可能穿入敦煌地块 北山杂岩中 ,但为后期近Ew向推覆构造所“掩盖” ,侵入活动是一重要证据 ;②区域加里东期岩浆活动应为一期重要的岩浆 热事件。No isotopic dating of granodiorites along the Bagexia-Heidaban zone in the western part of North Qilian Mountains was made by previous workers.They were commonly thought to be products of Late Variscan.Nevertheless,U-Pb single-zircon dating conducted by the authors show that these granodiorites are 481.6±3.3 Ma in age,thus belonging to Ordovician.The Altun fault belt might have been formed earlier than 481.6±3.3 Ma.Geological significance of these age data is also discussed in this paper.

关 键 词：北祁连山 花岗闪长岩 成岩时代 阿尔金断裂 活动时间 

分 类 号：P542.3[天文地球—构造地质学] P588.122[天文地球—地质学]