库鲁克塔格兴地塔格群变质石英岩复杂锆石特征及指示意义  

Complex Zircon Features and Indicative Significance of Metamorphic Quartzite in Kuruktage Xingditage Group

作　　者：宋志豪 刘桂萍 郭瑞清 玛依拉·艾山 崔涛 Song Zhihao;Liu Guiping;Guo Ruiqing;Mayila·Aishan;Cui Tao(College of Geology and Mining Engineering,Key Laboratory of Xinjiang Autonomous Region for continental dynamics and metallogenic prediction of Central Asian orogenic belt,Xinjiang University,Urumqi,Xinjiang,830047,China;College of resources and Earth Sciences,China University of mining and technology,Xuzhou,Jiangsu,221116,China)

机构地区：[1]新疆大学,新疆中亚造山带大陆动力学与成矿预测自治区重点实验室,地质与矿业工程学院,新疆乌鲁木齐830047 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《新疆地质》2021年第1期55-66,共12页Xinjiang Geology

基　　金：自治区级大学生创新训练计划项目库鲁克塔格地区孔兹岩系中复杂锆石成因分析及年代学研究(S201910755036);国家自然科学基金项目新疆库鲁克塔格地区古元古代深熔混合岩变质作用P-T-t轨迹及其对碰撞造山过程的约束(41762015)共同资助。

摘　　要：造山带内造山作用时限的划分是识别超大陆的重要依据。为找寻库鲁克塔格古元古代晚期造山作用与锆石微区特征间的联系,运用LA-ICP-MS技术分析了石英岩中64个锆石U-Pb同位素点。结果显示:ΣREE=47×10^(-6)~490×10^(-6)(40个点,下同),570×10^(-6)~1384×10^(-6)(24);Th/U<0.4(33),Th/U>0.4(31);Ti=16×10^(-6)~50×10^(-6)(37),50×10^(-6)~251×10^(-6)(27);Gd/Yb=0.03~0.8(45),Gd/Yb=1.3~4.7(19),元素含量变化范围大,表明各微区锆石成因的不同。综合分析锆石各微区成因,分别为微区Ⅰ:岩浆成因(~2.5 Ga);微区Ⅱ:热液改造残留(2.3~2.0 Ga);微区Ⅲ①:热液成因(~1954 Ma);微区Ⅲ②、微区Ⅳ:变质成因(~1924 Ma、~1945 Ma)。由内而外年龄减小,整体呈升温增压的趋势,代表一个进变质作用过程,在锆石边部达到变质峰期。结合前人研究成果,认为微区Ⅳ(~1945 Ma)可能形成于板块俯冲作用下,微区Ⅲ②(~1924 Ma)可能在板块碰撞环境下形成。The division of orogenic time limits in orogenic belts is an important basis for identifying supercontinents.To find the relationship between late paleoproterozoic orogeny and zircon microzonal features,64 zircon U-Pb isotopic spots in quartzite were analyzed by LA-ICP-MS.The results showed that:ΣREE=47×10^(-6)~490×10^(-6)(40 points,the same below),570×10^(-6)~1384×10^(-6)(24);Th/U<0.4(33),Th/U>0.4(31);Ti=16×10^(-6)~50×10^(-6)(37),50×10^(-6)~251×10^(-6)(27);Gd/Yb=0.03~0.8(45),1.3~4.7(19),The variation range of element content is large,which indicates that the origin of zircon in each micro area is different.Analysis the genesis of zircon microregions,respectively:the micro areaⅠ:magmatic origin(~2.5Ga);Ⅱ:hydrothermal transformation(2.3~2.0 Ga);Ⅲ①:hydrothermal(~1954 Ma);Ⅲ②、Ⅳ:metamorphism(~1924 Ma,~1945 Ma).From the inside out,the age decreases,and the overall trend is to increase temperature and pressure,which should represent a process of metamorphism,reachingthe metamorphic peak at the edge of the zircon.In combination with the previous research results in this region,the hydrothermal genesis of 1945 Ma may be formed in the hightemperature environment with subduction,and the metamorphic genesis of 1924 Ma may be formed in the high-pressure environment with collision.This study provides time constraints for the inter plate orogeny in this area.

关 键 词：锆石成因 造山作用 微量元素 古元古代 库鲁克塔格 

分 类 号：P313.6[天文地球—固体地球物理学] P588.341[天文地球—地球物理学]