CAJ | 학술논문

隆务峡蛇绿岩位于青海省同仁县,大地构造位置处于西秦岭和南祁连造山带的结合部位.蛇绿岩年代学对于研究造山带构造演化和恢复古洋-陆板块构造格局至关重要.对隆务峡蛇绿岩中的辉长岩进行了LA-ICP-MS锆石U-Pb定年.~(206)Pb/~(238)U加权平均年龄为250.1Ma±2.2Ma(MSWD=0.7),代表了辉长岩的结晶年龄,表明隆务峡蛇绿岩是晚二叠世-早三叠世西秦岭与南祁连之间古洋盆扩张过程中岩浆活动的产物.而呈岩株侵入到蛇绿岩中的花岗闪长岩的年龄(244Ma±1.4Ma)晚于蛇绿岩中辉长岩的年龄,但早于区域上大量存在的印支期花岗岩.可能记录了蛇绿岩的侵位时代.
륭무협사록암위우청해성동인현,대지구조위치처우서진령화남기련조산대적결합부위.사록암년대학대우연구조산대구조연화화회복고양-륙판괴구조격국지관중요.대륭무협사록암중적휘장암진행료LA-ICP-MS고석U-Pb정년.~(206)Pb/~(238)U가권평균년령위250.1Ma±2.2Ma(MSWD=0.7),대표료휘장암적결정년령,표명륭무협사록암시만이첩세-조삼첩세서진령여남기련지간고양분확장과정중암장활동적산물.이정암주침입도사록암중적화강섬장암적년령(244Ma±1.4Ma)만우사록암중휘장암적년령,단조우구역상대량존재적인지기화강암.가능기록료사록암적침위시대.
Longwu Gorge ophiolite belt located in Tongren Area,Qinghai Province,is at the jointing part of West Qinling and South Qilian orogenic belts.The ophiohte geochronology is very important for the study of tectonic evolution of orogenic belt and the reconstruction of the ancient ocean-land and plate tectonic fiamework.LA-ICP-MS zircon U-Pb dating of gabbro from the Longwu Gorge ophiohte suggests an isotopic age of (250.1±2.2)Ma (MSWD=0.7),which indicates that the Longwu Gorge ophiolite Was the product of magmatic activitiy during the process of extension of paleo-ocean basra along the jointing part of West Qinling and South Qilian in the late Permian to early Triassic.Zircons from the granodiotite intruding the ophiofite yielded an age of 244±1.4Ma,which was younger than the formation of ophiolite,but it is significantly older than the Indosinain collisional granitoids in the region.Therefore,it may reflect the emplacement age of the Longwu Gorge ophiolite.