中亚巴尔喀什成矿带萨亚克大型铜矿田矿床地质特征与成矿模式

GEOLOGICAL CHARACTERISTICS OF AND METALLOGENIC MODEL FOR LARGE-SCALE SAYAK COPPER ORE FIELD IN BALKHASH METALLOGENIC BELT,CENTRAL ASIA

综述了哈萨克斯坦巴尔喀什成矿带萨亚克大型铜矿田地质特征、矿田构造与成矿模式。萨亚克铜矿田是中亚成矿域巴尔喀什成矿带唯一的以矽卡岩型铜矿化为主的大型铜矿床,产在萨亚克地堑复向斜内。该矿田包括几个在空间上相对独立的矽卡岩型铜矿床、斑岩型铜钼网状脉矿床和一系列石英脉型矿脉,构成了斑岩型和矽卡岩型两个端元形成的成矿系列,但以矽卡岩型为主。矿床主要位于中石炭世灰岩与晚石炭世花岗岩类的接触带上,具有独特的矽卡岩型Cu-Au-Mo矿化组合,成矿时代为海西中晚期,根据本研究进行的锆石SHR I MP定年结果,主要与次要成矿期年龄分别为335±2Ma和308±10Ma。金属矿床主要赋存在地堑复向斜内局部发育的鞍状背斜顶部,部分富矿体的产出严格受断裂构造-岩浆活动的控制。闪长岩与铜矿化作用的关系最为密切,铜含量可高达1%以上;其次,花岗闪长岩与铜矿化的关系也较为密切,铜含量可达0.2%以上。萨亚克矽卡岩型铜矿田铜保有储量约为57.5万吨。

The Sayak ore field is the only area with the occurrence of large-scale skarn-type copper deposit in Balkhash metallogenic belt,Kazakhstan,Central Asia.In this paper the geological characteristics,ore-field structures and metallogenic model of Sayak ore field are described in detail.Sayak ore field is located in the Sayak graben-synclinorium,including several spatially isolated skarn copper deposits,porphyry Cu（Mo） deposits,Cu-Mo veins and a series quartz vein deposits,which consist of a metallogenic series with skarn-type and porphyry deposits as the two end deposits.The deposits in the ore-field are mainly located in the contact zone between the Middle Carboniferous limestones and the Late Carboniferous granitoids,with a special assemblage of skarn-type Cu-Au-Mo mineralizations.The metallogenic time of main copper deposits in Sayak ore-field is in the Middle to Late Hercynian,with the main and secondary metallogenic ages of 335 ± 2 Ma and 308 ± 10Ma,respectively.The ore bodies are mainly located in the saddle-top segments of locally developed anticlines in the graben-synclinorium,strongly controlled by the tectono-magmatism activities.The most relative granitoids with the copper metallogenesis in Sayak ore field are diorite with Cu content up to 1% and granodiorite up to 0.2%.The copper reserve in the Sayak ore field is estimated to be ～ 575 kt Cu.