南极北维多利亚地难言岛侵入岩LA-ICP-MS锆石U-Pb年龄及其地质意义  

LA-ICP-MS zircon U-Pb ages and geological constraint of intrusive rocks from the Inexpressible Island, Northern Victoria Land, Antarctica

作　　者：王伟[1] 胡健民[1] 陈虹[1] 于根旺 赵越[1] 刘晓春[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《地质通报》2014年第12期2023-2031,共9页Geological Bulletin of China

基　　金：国家极地专项(编号:CHINARE2014-02-05);国家自然科学基金项目(批准号:41202047)

摘　　要：对采自南极罗斯造山带中北维多利亚地难言岛的侵入岩进行了岩石学和锆石U-Pb同位素分析。难言岛的主要侵入岩类型为石英二长岩,并有少量石英二长闪长岩。采用LA-ICP-MS对石英二长岩和石英二长闪长岩样品进行锆石UTh-Pb同位素分析,获得石英二长岩的侵位年龄为482.4Ma±4.2Ma和484.3Ma±2.5Ma,石英二长闪长岩的侵位年龄为484.0Ma±3.0Ma,均为早奥陶世早期。难言岛石英二长岩和石英二长闪长岩岩浆应在伸展背景下侵位结晶,结合已有区域资料可以推测,在北维多利亚地罗斯造山运动应主要发生在寒武纪,并在早奥陶世早期之前趋于结束。In this paper, the authors investigated the petrology and zircon U-Pb geochronology of the intrusive rocks collected from the Inexpressible Island, Northern Victoria Land of the Antarctic Ross Orogen. The collected intrusive rocks are massive and nonfoli？ated quartz monzonite and quartz monzodiorite. LA-ICP-MS analyses yielded zircon U-Pb ages of 482.4Ma±4.2Ma and 484.3Ma± 2.5Ma for the quartz monzonite and 484.0Ma±3.0Ma for the quartz monzodiorite. Both types of the rocks were emplaced and crys？tallized during the early stage of the early Ordovician. The magma of the quartz monzonite and the quartz monzodiorite should have been emplaced in an extensional setting. In conjunction with the previously reported data in the adjacent areas, it could be inferred that in the Northern Victoria Land the Ross Orogen developed mainly in the Cambrian and transformed to the late stage of orogeny or post-tectonic regime before the early stage of the early Ordovician.

关 键 词：北维多利亚地 石英二长岩 石英二长闪长岩 LA-ICP-MS锆石U-PB年龄 罗斯造山带 南极 

分 类 号：P597.3[天文地球—地球化学]