新疆博格达晚石炭世构造-岩浆活动:来自基性侵入岩地球化学、年代学约束  

Late Carboniferous tectono-magmatic activity in Bogda Orogen:Constraints from the rock geochemistry,geochronology of basic intrusive rocks

作　　者：崔玉宝 李旭 王新录 朱国栋 CUI Yubao;LI Xu;WANG Xinlu;ZHU Guodong(Shaanxi Provincial Key Project Reserve and Promotion Center,Xi’an 710016,Shaanxi,China;Shaanxi Mineral Geological Survey Center,Xi’an 710054,Shaanxi,China;Regional Geological Survey Academe Of Shaanxi Geology And Mining Group Co.,Ltd.,Xianyang 712000,Shaanxi,China)

机构地区：[1]陕西省重大项目储备推进中心,陕西西安710016 [2]陕西省矿产地质调查中心,陕西西安710054 [3]陕西地矿区研院有限公司,陕西咸阳712000

出　　处：《矿产勘查》2023年第3期335-347,共13页Mineral Exploration

基　　金：新疆维吾尔自治区地质勘查基金项目“新疆东天山吉木萨尔林场一带1∶5万K45E002019、K45E002020、K45E002021、K45E002022四幅区域地质矿产调查”(T14-1-LQ08)资助。

摘　　要：吉木萨尔林场地区基性侵入岩位于博格达造山带西段,主要岩性为辉长岩、辉绿岩。岩体SiO_(2)含量45.18%~51.59%,富钠贫钾,Na_(2)O/K_(2)O为1.7~11.0,Na_(2)O+K_(2)O为2.47%~5.11%,里特曼指数δ(1.25~3.24)小于3.3,FeOT值为5.85%~15.47%,铝饱和指数A/CNK为0.57~0.98,Mg^(#)值37.37~67.75,属准铝质低钾—钙碱性系列。稀土总量21.17×10^(-6)~96.98×10^(-6),LREE/HREE为1.73~3.10,La_(N)/Yb_(N)为0.87~2.18,轻、重稀土轻度分异或不明显,δEu(0.85~1.61)和δCe(0.95~1.04)负异常不明显。K、Pb、Sr、Ba等大离子亲石元素(LILE)相对富集,Th、Nb、P、Ta等高场强元素(HFSE)相对亏损。LA-ICP-MS锆石U-Pb年龄为(309.7±1.8)Ma,属晚石炭世。岩浆来自亏损地幔的部分熔融,结晶分异不明显,地壳物质混染强烈。岩体形成环境为大陆裂谷,同时也显示出大洋岛弧特征,指示岩体是博格达裂谷在晚石炭世由全面伸展向局限伸展转变的产物。The basic instructive rocks located in the west of Bogda Orogen.The main lithology is gabbro and diabase.These rocks are characterized by low SiO_(2)(45.18%-51.59%),K-rich and Na-poor,Na_(2)O/K_(2)O=1.7-11.0,Na_(2)O+K_(2)O=2.47%-5.11%,Rittman index(1.25-3.24)less than 3.3,FeO^(T) is 5.85%-15.47%,and A/CNK=0.57-0.98,Mg^(#)=37.37-67.75,belonging to metaluminous low-K calc-alkaline rock series.The total content of rare earth elements are 21.17×10^(-6)-96.98×10^(-6),La_(N)/Yb_(N) is 0.87-2.18,with indistinct or weak fractionation between light rare earth element(LREE)and heavy rare earth element(HREE),with no significant negative Eu and Ce anomalies.The basic instructive rocks are rich in LILE,and poor in HFSE.The LA-ICP-MS zircon U-Pb age of gabbro is(309.7±1.8)Ma,belonging to Late Carboniferous.Magma came from the partial melting of depleted mantle,with no occurrence of crystallization differentiation,but with strong crustal contamination.The tectonic environment of rocks is continental rift,but also with characters of ocean islands,which may indicate the basic instructive rocks were formed during transitional stage from extension to local extension in Bogda Orogen.

关 键 词：基性侵入岩 岩石地球化学 年代学 构造环境 博格达造山带 新疆 

分 类 号：P581[天文地球—岩石学]