西昆仑三十里岩体黑云母二长花岗岩和暗色包体锆石U-Pb年代学、地球化学特征、Sr-Nd同位素组成及其地质意义  

U-Pb geochronology,geochemical characteristics,Sr-Nd isotopic compositions,and geological significance of granites and mafic magmatic enclaves from Sanshili,West Kunlun Orogen

作　　者：周楷麟 魏小鹏 贺国锐 王核[1] 闫庆贺 张晓宇 董瑞 ZHOU Kailin;WEI Xiaopeng;HE Guorui;WANG He;YAN Qinghe;ZHANG Xiaoyu;DONG Rui(Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Sichuan Branch of China National Geological Exploration Center of Building Materials Industry,Chengdu 610052,Sichuan,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]中国建筑材料工业地质勘查中心四川总队,四川成都610052

出　　处：《地球化学》2024年第2期257-276,共20页Geochimica

基　　金：新疆维吾尔自治区重大科技专项(2020A03005-3);国家自然科学基金项目(91962215、41972088和42002073)联合资助。

摘　　要：三十里岩体位于西昆仑造山带东段甜水海地体北缘,本文对三十里岩体黑云母二长花岗岩及其暗色包体进行了锆石U-Pb年代学和全岩地球化学、同位素地球化学研究。结果表明:黑云母二长花岗岩SiO_(2)含量为67.84%~68.95%,Al_(2)O_(3)含量为14.77%~15.28%,铝饱和指数A/CNK为1.02~1.06,属于弱过铝质岩石;强烈富集LREE,具有轻微Eu负异常;富集Rb、Th、K、La、Ce等大离子亲石元素,亏损Nb、Ta、Ti和P等高场强元素。锆石U-Pb测年结果显示,黑云母二长花岗岩及其暗色包体均形成于约216 Ma,二者有相似的Sr-Nd同位素特征及二阶段模式年龄。暗色包体为岩浆混合作用的产物。Sr-Nd同位素数据表明,黑云母二长花岗岩可能由前寒武纪变质火成岩和变质沉积岩的混合物部分熔融形成。结合区域地质和本次研究成果,三十里岩体应属于碰撞后阶段的产物。The Sanshili granite pluton is located in the northern margin of the Tianshuihai terrane in the eastern part of the West Kunlun Orogen.This paper reports the geochronology and elemental and isotopic geochemical characteristics of granites and mafic magmatic enclaves(MMEs)from the Sanshili granite pluton.The pluton mainly consists of biotite monzogranite that has SiO_(2) and Al2O3 contents in the ranges of 67.84%to 68.95%and 14.77%to 15.28%,respectively,and shows weak peraluminous affinity(A/CNK=1.02–1.06).The biotite monzogranite samples are characterized by strong enrichments of LREE and large ion lithophile elements such as Rb,Th,K,La,and Ce,insignificant negative Eu anomalies,and depletion of high-field-strength elements such as Nb,Ta,Ti,and P.Zircon U-Pb dating results show that the monzogranite and MMEs are coevally,crystallized at ca.216 Ma,with similar Sr-Nd isotopic compositions and model ages.The geochemical and mineralogical features indicate that the Sanshili granite is of I-type.Harker oxide diagrams and photomicrographs show that MMEs are the outcomes of magma hybridization.Sr-Nd isotope modeling demonstrates that the Sanshili biotite monzogranite was likely formed by partial melting of a mixing source of the Precambrian metaigneous and metasedimentary rocks in a post-collision environment.

关 键 词：西昆仑造山带 地球化学 花岗岩 暗色包体 三十里 岩石成因 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]