全吉地块莫河片麻岩原岩侵位年龄的再研究  

Re-Determining the Intrusion Age for the Protolith of the Mohe Gneiss in the Quanji Massif

作　　者：巴金[1,2] 龚松林[3] 廖梵汐[1] 张璐[1] 

机构地区：[1]中国地质大学地球科学学院,武汉430074 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [3]中国地质大学教育部三峡库区地质灾害研究中心,武汉430074

出　　处：《地质科技情报》2012年第6期98-101,共4页Geological Science and Technology Information

基　　金：国家自然科学基金项目(40972042;40772041)

摘　　要：莫河片麻岩位于全吉地块东段,其原岩为花岗闪长质-二长花岗质侵入体。前人对该片麻岩的锆石年龄测定结果相差约120Ma。在野外详细地质观察基础上重新采集样品,用LA-ICP-MS法重新测定了15颗岩浆成因锆石的U-Pb年龄,结果得上交点年龄为(2 394±31)Ma(2$)(MSWD=0.82)。由于锆石也受到变质变形作用的强烈改造,认为该年龄可能更接近于该片麻岩原岩的侵位年龄。新的定年结果表明,全吉地块存在近2.4Ga的花岗岩类侵入活动。The Mohe gneiss is located at the eastern part of the Quanji Massif. It is a strongly metamor- phosed and deformed granodioritic-monzograntic pluton. Previously reported zircon ages for intrusion of its protolith show a difference about -120 Ma. On the basis of detailed geological survey in the field, we re-collected sample and determined 18 U-Pb data on 15 magmatic zircons using LA-ICP-MS technique. The results show an upper intercept age of （2 394±31）Ma （2σ） （MSWD=0.82）. Since the zircons have been experienced intensive metamorphism and deformation, we consider that our result is more reasonable be-cause of the intrusion and crystallization age of the gneiss protolith. Our new dating result reveals a granit- ic intrusion event occurred at -2.4 Ga in the Quanji Massif.

关 键 词：莫河片麻岩 侵位年龄 全吉地块 

分 类 号：P588.345[天文地球—岩石学]