西天山东塔尔别克金矿区安山岩LA-ICP-MS锆石U-Pb年代学、元素地球化学与岩石成因  

LA-ICP-MS zircon U-Pb geochronology, element geochemistry and petrogenesis of the andesites in the eastern Taerbieke gold deposit of the western Tianshan region

作　　者：唐功建[1,2,3] 王强[1] 赵振华[1] Derek A WYMAN 陈海红[3] 贾小辉[1,2] 姜子琦[1,2] 

机构地区：[1]中国科学院广州地球化学研究所同位素年代学与地球化学重点实验室,广州510640 [2]中国科学院研究生院,北京100039 [3]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,武汉4300474 [4]悉尼大学地球科学学院地质与地球物理系

出　　处：《岩石学报》2009年第6期1341-1352,共12页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(2007CB411308);中国科学院知识创新项目(KZCX1-YW-15-2;KZCX2-YW-128);国家自然科学基金项目(40721063和40673037)的资助.

摘　　要：东塔尔别克金矿区位于西天山吐拉苏盆地内阿希金矿区南侧,构造上属于伊犁-中天山微板块与准噶尔板块之间的博罗科努早古生代岛弧带西段。东塔尔别克矿区出露有一些安山岩,这些岩石具有典型高镁安山岩特征,如高硅(SiO_2=58.94%～63.85%),具有较高的MgO含量(3.75%～6.59%)和Mg~#(58～69)、高的Cr(94.2×10^(-6)～241×10^(-6))、和Ni (54.5×10^(-6)～126×10^(-6))含量,以及低的FeO^T/MgO比值。除了Sr含量略微偏低(235×10^(-6)～696×10^(-6))之外,这些岩石基本显示了埃达克岩的地球化学特征:高的Al_2O_3(15.39%～16.65%),低Y(9.86×10^(-6)～14.9×10^(-6))含量,以及高的Sr/Y比值(23.8～48.1),无Eu异常,Nb、Ta、Ti亏损等。LA-ICP-MS锆石U-Pb测年结果显示安山岩的年龄为347.2±1.6Ma,为早石炭世。安山岩富集Rb、Th、U等大离子亲石元素,相对亏损Nb、Ta、Ti等高场强元素,轻重稀土元素分馏明显,具有俯冲带岛弧岩浆的特征。东塔尔别克安山岩可能形成于岛弧环境中,并可能由俯冲的晚古生代北天山洋洋壳以及少量上覆沉积物熔融形成,产生的熔体在上升过程中与地幔橄榄岩发生了相互作用.熔体-地幔相互作用对区内金矿的形成具有重要意义。The eastern Taerbieke gold deposit is geographically located to the south of the Axi gold deposit in the 'Fulaski basin, western Tianshan, and tectonically occurs in the western section of the Early Paleozoic Borohoro island are between the Junggar plate to the north and the Yili-central Tianshan micro-plate to the south. The eastern Taerbieke andesites are geochemcially similar to high-Mg andesite, e. g. high SiO(2)(58.94% similar to 63.85%) and MgO contents (3.75%similar to 6.59%), Mg values(58 similar to 69), and 0 (94, 2 x 10(-6) similar to 241 x 10(-6) and Ni (54.5 x 10(-6) similar to 126 x 10(-6)) contents, and low FeO(T)/MgO ratios. Except for slight low Sr contents ( 235 x 10(-6)similar to 696 x 10(-6)), they are also geochemically similar to adakites, e. g., high Al(2)O(3) (15. 39% similar to 16.65%), high Sr/Y(23.8 similar to 48.1) ratios, no significant Eu anomalies and clear depletion in Nb, Ta and Ti. LA-ICP-MS U-Pb age data suggest that [lie eastern Taerbieke andesites were generated in the Early Carboniferous (347.2 +/- 1.6Ma). The enrichment in large ion lithophile elements (e.g. Rb, Th and U) and depletion in high field strength elements ( e. g. Nb, Ta and Ti), and higher light rare earth element contents relative to heavy rare earth elements for the andesites, suggest that they are similar to island are rocks. We Suggest that the eastern Taerbieke andesites were possibly generated by the interaction between mantle. and melts derived by partial inching of subducting sediments and altered oceanic crust during the subduction of Late Paleozoic northern Tianshan Ocean. The interaction between mantle and melts possibly played an important role in generating An mineralization.

关 键 词：LA-ICP-MS锆石U-PB定年 高镁埃达克岩 金矿化 岛弧 西天山 

分 类 号：P588.144[天文地球—岩石学] P597.3[天文地球—地质学]