塔里木西南缘晚志留世辉绿岩U-Pb锆石年龄、地球化学及其地质意义  

U-Pb Zircon Age,Geochemistry and Geological Significance of the Late Silurian Diabase in the Southwest Margin of Tarim

作　　者：魏博 齐琦 王利伟 张旗 王伟平 冯旻譞 WEI Bo;QI Qi;WANG Liwei;ZHANG Qi;WANG Weiping;FENG Minxuan(Northwest Geological Exploration Institute of China Metallurgical Geology Bureau,Xi’an 710119,Shaanxi,China;Xi'an Center of China Geological Survey/Northwest China Center for Geoscience Innovation,Xi’an 710119,Shaanxi,China)

机构地区：[1]中国冶金地质总局西北地质勘查院,陕西西安710119 [2]中国地质调查局西安地质调查中心/西北地质科技创新中心,陕西西安710119

出　　处：《西北地质》2025年第2期288-301,共14页Northwestern Geology

基　　金：中国地质调查局项目“塔里木盆地西南缘锰多金属矿产地质调查”(121201001000150013);“全国地质调查组织实施费”(DD20221837);陕西省自然科学基础研究计划项目(2022JQ-272)联合资助。

摘　　要：塔西南缘铁克里克构造带叶城一带古元古代花岗岩体及赛图拉岩群中大量发育辉绿岩脉(墙)群,通过对其进行详细的地质、年代学、地球化学和构造环境研究,结果表明,该辉绿岩属于亚碱性拉斑玄武岩系列,具有高Fe、Ti,富Na,贫K的特征,球粒陨石标准化稀土元素配分图表现为LREE略富集的右倾分配模式,富集大离子亲石元素,相对亏损高场强元素,具有板内玄武岩特征。岩石成因研究表明,其具亏损岩石圈地幔源区特征,并受俯冲流体或熔体交代混染,原始岩浆源区主要为尖晶石二辉橄榄岩。辉绿岩形成于板内拉张环境。辉绿岩获得LA-ICP-MS锆石U-Pb年龄为(424±2.7)Ma,形成于晚志留世,结合西昆仑区域构造演化,认为该时期处于造山期后阶段,代表了原特提斯洋构造旋回的结束。辉绿岩中含有大量捕获锆石,第一组捕获锆石年龄为(2 242±19)Ma,表明铁克里克陆块确实存在古元古代结晶基底,第二组捕获锆石年龄为(1 842±42)Ma,代表了塔里木克拉通古元古代晚期的岩浆和构造记录。There are a large number of diabase dikes(walls)developed in the paleoproterozoic granite body and Setula Group in the Yecheng area of Tiekerike structural belt,southwestern margin of Tarim Basin.Through detailed geological, chronological, geochemical and tectonic environment studies, the results show that the diabases belong to the subbasic lapidous basalt series, with the characteristics of high Fe, Ti, Na and low K.The chondrite normalized REE patterns show the slightly enriched of LREE, which are right-sloping distribution. The diabases enrich LILEs and relatively loses HFSEs, resembling the feature of intraplate basalts. The study of lithogenesis showed that the diabases had the characteristics of a depleted lithospheric mantle source, and were mixed by subduction fluid or melt, and the original magma source area were mainly spinel dipyroxene peridotite. Diabases were formed in an intraplate tensioning environment. The LA-ICP-MS zircon U-Pb age of (424±2.7) Ma was obtained from diabase, formed in the Late Silurian, combined with the tectonic evolution of the West Kunlun region, it is believed that this period is in the post-orogenic stage, representing the end of the tectonic cycle of the original Proto-Tethyan Ocean. Diabases contain a large amount of inherited zircon, the first group inherits the zircon age of (2 242±19) Ma, which indicates that there is a Paleoproterozoic crystalline basement in the Tiekerek block, and the second group inherits the zircon age of (1 842±42) Ma, representing the magmatic and tectonic records of late Paleoproterozoic Tarim Craton.

关 键 词：辉绿岩 西昆仑 锆石U-Pb年龄 原特提斯洋 Columbia超大陆 塔西南缘 

分 类 号：P584[天文地球—岩石学]