新疆西昆仑阿喀孜花岗岩地球化学特征及时代意义  

The Geochemistry and Geochoronology Significance of Akazi Granites in Western Kunlun,Xinjiang

作　　者：杨维文 郑玉壮[1] 邓建[1] 张燕波[2] 

机构地区：[1]新疆维吾尔自治区地质矿产勘查开发局第十一地质大队,新疆昌吉831100 [2]新疆大学,新疆乌鲁木齐830046

出　　处：《新疆地质》2014年第2期141-146,共6页Xinjiang Geology

基　　金：新疆维吾尔自治区1:5万区域地质矿产调查(XJQDZ2009-10)项目资助

摘　　要：西昆仑阿喀孜岩体侵位于中太古界赫罗斯坦岩群中,普遍发生混合岩化。主要由片麻状黑云角闪二长花岗岩和黑云钾长花岗岩组成,属铝饱和钙碱性系列。球粒陨石标准化的REE分布型式表现为轻稀土元素（LREE）相对于重稀土元素（HREE）富集（（La/Yb）N=10.66~97.36）、轻重稀土分异的特征。样品的Eu显示负异常（δEu=0.25~0.84）,具前寒武纪花岗岩特征。花岗岩中富集大离子亲石元素Rb,Ba,Ce,表明古元古代地壳不成熟。对阿喀孜岩体片麻状二长花岗岩中的锆石进行LA-ICP-MS U-Pb同位素测年,结果为（2 335±2.8）Ma,代表阿喀孜岩体的生成年龄。结合花岗岩构造环境判别图解,表明阿喀孜岩体为太古宙赫罗斯坦岩群重熔形成,继承了太古宙岩石地球化学特征,为塔里木古陆核增生的产物。Akazi granites of Western Kunlun invasion in the Heluositan rock groups of Mid-Archeozoic,consist of gneissic granites and biotite moyites,are saturated calcium aluminum base nature series,mainly migmatization.Chondrite normalized REE pattern shows the characteristic of LREE enrichment（（La/Yb）N=10.66~97.36） and differentiation,with negative Eu anomalies（δEu=0.25~0.84）,with Precambrian granite features;Compare with the ORG,the granite samples are enriched in LILE（Rb,Ba,Ce）,suggest that the crust of Paleoproterozoic immaturity.The authors conducted LA-ICP MS Zircon U-Pb isotopic dating of the gneissic granite of Akazi,and the result shows that the age of gneissic granite is（2 335±2.8） Ma,which should be the original rock age of Akazi intrusive.These charasteristics along with element discrimination diagrams of granites,indicate that Akazi granites from remelt of Heluositan rock groups,inherited geochemistry characteristics of Archean rocks,and the products of crustal growth of Tarim block.

关 键 词：西昆仑 塔里木古陆 阿喀孜岩体 锆石LA-ICP-MS U-PB测年 地球化学特征 

分 类 号：P588.121[天文地球—岩石学]