西准噶尔成矿带晚古生代花岗岩类岩浆活动及其构造意义  

Late Paleozoic Granitic Magmatism in West Junggar Metallogenic Belt(Xinjiang), Central Asia, and its Tectonic Implication

作　　者：黄鹏辉[1] 陈宣华[2] 王志宏[2] 叶宝莹[3] 李学智 杨屹 

机构地区：[1]北京市地质工程设计研究院,北京101500 [2]中国地质科学院,北京100037 [3]中国地质大学(北京),北京100083 [4]新疆地质调查院,新疆乌鲁木齐830000

出　　处：《大地构造与成矿学》2016年第1期145-160,共16页Geotectonica et Metallogenia

基　　金：国家科技支撑计划重点项目暨国家305项目(2007BAB25B02);中国地质调查局地质调查项目(1212011120184);国家深部探测技术与实验研究专项(Sino Probe-08)联合资助

摘　　要：中亚造山带是晚古生代地壳显著生长与大规模成矿的重要地区。本文采集了中亚造山带西部的西准噶尔成矿带哈图-别鲁阿嘎希及其附近地区11个岩体共33件花岗岩类样品,对其开展了岩石地球化学与同位素示踪等研究,厘定了该地区晚古生代岩浆活动的特点与大地构造环境,并与哈萨克斯坦境内的巴尔喀什成矿带晚古生代岩浆活动进行了对比。研究表明,哈图地区晚石炭世花岗岩类主要为后碰撞伸展构造环境的A型花岗岩类,别鲁阿嘎希等地区存在洋内俯冲与岛弧环境的埃达克岩,显示了西准噶尔晚古生代构造环境时空变化的复杂性。该地区花岗岩类εNd(t)值较高(+4.62^+7.53)、εSr(t)值为(-57.61^+18.21),具有中亚造山带花岗岩类的共同特征,为古生代增生的新生陆壳,其源区与亏损地幔组分具有亲缘关系,这与巴尔喀什成矿带东段的花岗岩类具有一致性。花岗岩的^(206)Pb/^(204)Pb、^(207)Pb/^(204)Pb和^(208)Pb/^(204)Pb比值范围分别为18.2776~19.1677、15.5260~15.5796和38.2080~39.0821,为造山带花岗岩类。Crustal growth and metallogeny of the Central Asia Orogenic Belt（CAOB） in the Late Paleozoic is significant. In this study, 33 samples from 11 granitoid plutons in the Hatu and Bielu’agaxi areas in the West Junggar metallogenic belt（Xinjiang）, CAOB, were analyzed. We determined the tectonic environments of the West Junggar granitoids through chemical analyses, and correlated them to the granitoids in the Balkhash metallogenic belt, Kazakhstan through isotopic tracing. The Late Carboniferous granitoids in the Hatu area are mainly of A-type formed in the post-collisional extensional tectonic setting. Meanwhile, adakites formed in the Bielu’agaxi area due to intra-ocean plate subduction. The results show the complicated tectonic setting in the West Junggar. All these granitoids have characteristic high εNd（t） ranging from ＋4.62 to ＋7.53, and εSr（t） ranging from -57.61 to ＋18.21, suggestive of Paleozoic continental crust with affinity of depleted mantle source, which are similar to those in the other parts of the CAOB. ~206Pb/~204 Pb, ~207Pb/~204 Pb, and ~208Pb/~204 Pb ratios are in ranges of 18.2776–19.1677, 15.5260–15.5796, and 38.2080–39.0821, respectively, suggesting an orogenic setting for the granitoids, similar to those granitoids from the Tianshan Mountains, the Altai Mountains, and the Balkhash metallogenic belt.

关 键 词：西准噶尔 晚古生代 花岗岩类 中亚造山带 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]