东昆仑白干湖钨锡矿床成矿岩体岩石学、年代学和地球化学  

Petrology,geochronology and geochemistry of metallogenetic granite in Baiganhu W-Sn deposit,East Kunlun

作　　者：周建厚[1] 丰成友[1] 李大新[1] 王辉[1] 张明玉[1] 李国臣[2] 王增振[3] 

机构地区：[1]中国地质科学院矿产资源研究所、国土资源部成矿作用与资源评价重点实验室,北京100037 [2]核工业北京地质研究院,北京100029 [3]教育部造山带与地壳演化重点实验室、北京大学地球与空间科学学院,北京100871

出　　处：《岩石学报》2015年第8期2277-2293,共17页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41172076);中国地质调查局地质调查项目(1212011085528);中国地质调查局高层次地质人才培养计划(201309);中国地质调查局青年地质英才计划(201112)联合资助

摘　　要：白干湖钨锡矿田是近年来在我国西部地区新发现的一个具超大型远景规模的矿田,由白干湖、柯可卡尔德、巴什尔希和阿瓦尔四个矿床组成。矿床与加里东期巴什尔希岩浆序列具有密切联系,但对其岩石成因及与成矿关系尚有争议。本文选取白干湖矿床与成矿有关的花岗岩开展了岩石学、年代学和地球化学研究。镜下鉴定其为正长花岗岩。LA-MC-ICP-MS锆石U-Pb年龄为413.6±2.4Ma（MSWD=0.36,n=30）。结合前人资料,认为巴什尔希岩浆序列形成于后碰撞构造环境,岩体年龄集中于中志留世-早泥盆世（ca.433~413Ma）,具有S型花岗岩和A型花岗岩伴生的特点。其中白干湖正长花岗岩含有原生锰铝榴石和白云母等过铝质矿物,A/CNK和A/NK分布范围分别为1.07~1.11和1.45~1.49,锆石饱和温度和高场强元素含量相对较低,属于弱过铝质高钾钙碱性S型花岗岩,形成于巴什尔希岩浆序列岩浆活动晚期,与区内钨锡成矿关系密切,矿区内下步找矿应对隐伏或岩枝状产出的正长花岗岩更加重视。而巴什尔希岩浆序列中的二长花岗岩和碱长花岗岩含有角闪石和黑云母等暗色矿物并主要呈他形晶充填于长石和石英晶隙,K2O含量为5.25%~6.29%,属于钾玄岩系列,A/CNK为0.92~1.02,其锆石饱和温度（866~917℃）、全碱含量（8.30%~9.69%）、稀土总量（200×10^-6~413×10^-6）和Zr、Nb、Ce、Y等高场强元素含量（Zr＋Nb＋Ce＋Y=556×10^-6~1006×10^-6）都明显偏高,为准铝质或弱过铝质A型花岗岩,在该区及外围可能具有形成与A型花岗岩有关的稀有稀土金属矿床的潜力。Baiganhu tungsten-tin ore field is located in Ruoqiang County,Xinjiang. It is in the west of Qimantage mountain,East Kunlun and consists of four deposits of Baiganhu,Kekekaerde,Bashierxi and Awaer. These deposits are spatially associated with the Caledonian Bashierxi Magmatic Series. With particular focus on the Baiganhu deposit,we conducted detailed studies on the petrology,geochronology and geochemistry of the causative granite and discuss its characteristics,genetic type and the relationship with W-Sn mineralization. The causative granite is syenogranite based on slice identification. LA-MC-ICP-MS zircon U-Pb dating reveals that the syenogranite was emplaced at 413. 6 ± 2. 4Ma（ MSWD = 0. 36,n = 30）. Our and previously published ages and geochemical data of the plutons in the Baiganhu area together show that the S-type granites and A-type granites are coexisting in Bashierxi Magmatic Series and they were formed in a post-collisional setting during the Middle Silurian-Early Devonian（ 433 ~ 413Ma）. Baiganhu syenogranite contains magmatic garnets and muscovites and the values of A / CNK and A / NK are in the range of 1. 07 ~ 1. 11 and 1. 45 ~ 1. 49,respectively,with a relatively low zircon saturated temperature and high field strength elements（ HFSEs） content. Thus this pluton is peraluminous and high-K calc-alkaline S-type granite. It formed during the late stage of Bashierxi Magmatic Series and has a closely genetic connection with the tungsten-tin mineralization. We suggest that more attention should be payed to the buried or apophysis-like syenogranite during the further exploration for tungsten-tin in this area. Whereas the monzogranite and alkali feldspar granite contain hornblendes and biotites which penetrate in the interstices between magmatic feldspar and quartz or even enclave magmatic quartz. They have relatively high K2 O content（ 5. 25% ~ 6. 29%）,with A / CNK ranging from 0. 92 to 1. 02,thus belong to metaluminous or weakly peraluminous shoshonite series. Their zircon saturated tempe

关 键 词：花岗岩成因类型 钨锡矿床 稀有稀土矿床 白干湖 东昆仑 

分 类 号：P618.67[天文地球—矿床学]