北祁连山东段新元古代火山岩的年代学证据  

Chronological evidence of Neoproterozoic volcanic rocks in the eastern segment of the North Qilian Mountains

作　　者：于福生[1] 王春英 杜国民[3] 

机构地区：[1]中国科学院高能物理研究所,北京100039 [2]甘肃省第三地质勘察院,甘肃兰州730050 [3]宜昌地质矿产研究所,湖北宜昌443000

出　　处：《中国地质》2002年第4期360-363,共4页Geology in China

基　　金：原地质矿产部1:万(石门川幅)区域地质调查项目

摘　　要：在1∶5万石门川幅、老龙湾幅区域地质调查时发现,北祁连山东段上吊吊坡地区存在一套不同于下奥陶统阴沟群的火山岩,经全岩样品Sm-Nd同位素测定,获得Sm-Nd等时线年龄为(723±25.0)Ma,表明其形成时代为新元古代。地球化学特征表明该套火山岩形成于岛弧环境,说明当时北祁连东段仍处于洋壳俯冲挤压环境。According to the geological survey of 1∶50000Shimenchuan Sh eet and Laolongwan Sheet,vol-canic rocks different from those in the Early Or dovician Yingou Goup have been found in the Shandiao-diaopo area,Jingtai Count y in the eastern segment of the North Qilian Mountains .Sm-Nd isochron dat-ing of the volcanic rocks shows that they formed during the Neoproterozoic, about 723million years ago.REE and trace element and trace element geochem ical characteristics suggest that a compressional environ-ment resulting from subduction of oceanic crust occurred there at that time.

关 键 词：新元古代 岛弧 火山岩 祈连山 钐-钕同位素 形成时代 

分 类 号：P588.1[天文地球—岩石学]