【作者】 李国臣；

【导师】 王瑞江；

【作者基本信息】 中国地质科学院 ， 构造地质学， 2012， 硕士

【摘要】 新疆白干湖钨锡矿田位于新疆维吾尔自治区若羌县境内,于2001年由吉林地质调查院发现,分布有柯可·卡尔德矿床、白干湖矿床、巴什·尔西矿床和阿瓦尔矿床,各矿床具相似的围岩和成矿岩体,矿床类型包括石英脉型、矽卡岩型、云英岩型,是一个一体多型的大型钨锡矿田,成矿受金水口群地层、各级断裂构造系统及加里东期二长花岗岩控制。矿田构造可划分成矿前、成矿期和成矿后构造,晚期构造对早期有继承、置换、叠加和复合现象,都充填了构造-流体作用的产物—脉体。矿田构造亦有分级控制特点,白干湖超壳大断裂通过控制地层分布和岩浆活动控制着矿田产出位置和等间距线性分布；白干湖剪切作用形成的次级断裂、矿区花岗岩内外接触带构造及岩浆派生的水力-热致断裂、冷却收缩裂隙控制着矿体的产出,为容矿构造。构造-流体有多阶段脉动活动特点,在平面上呈现平行、雁行排列规律。流体包裹体主要有气液两相、含子盐气液三相、单一液相(包括纯水和纯CO2型)、含CO2气液三相、同时含CO2和子盐气液四相等5种类型。成矿前构造热液形成的石英以前两种包裹体为主,有少量含CO2气液三相型,温度160～417℃,盐度6.16%-18.8wt%NaCl,受到成矿期热液作用叠加。成矿期石英温度125～370℃,盐度0.21%-15.17wt%NaCl,其中早阶段是钨锡的主成矿阶段,包含五种类型包裹体,温度239～370℃,盐度0.21%-15.17wt%NaCl,晚阶段主要为气液两相型,温度125～205℃,盐度6.6%-9.6wt%NaCl;成矿后石英包裹体主要为气液两相型,温度178-263℃,盐度6.3%9.08wt%NaCL激光拉曼探针分析表明成矿流体主要成分为H2O和CO2,气相含少量CH4和N2；氢、氧同位素研究结果显示三期流体分别主要为变质热液、岩浆热液和大气降水。该矿床系中高温、中低盐度的岩浆热液矿床,早期流体经历了不混溶作用,而混合作用可能贯穿整个成矿过程,这些是促使矿质沉淀的主要因素。矿田内发育复式岩体,利用SIMS锆石U-Pb法对矿田东北部似斑状二长花岗岩和中粗粒钾长花岗岩测得年龄分别为421±4Ma和422±4Ma。矿区内云英岩化矿化花岗岩脉和钨锡矿石英脉两侧云母线白云母39Ar-40Ar坪年龄分别为411.7±2.6Ma和412.8±2.4Ma。这些资料表明区内岩浆一成矿作用事件是连续的,代表了该地区加里东期(晚志留世)大规模成岩成矿事件。复式岩体具A型花岗岩的特征,成岩背景为晚造山拉伸环境,且岩体富含成矿元素,是白干湖钨锡多金属矿床的成矿母岩,也是白干湖钨锡多金属矿田成矿系统的中心。成矿演化模式总结为同生沉积期→变质变形矿化期→热液成矿期→后生热液期→表生氧化期演化过程,而热液成矿期又分矽卡岩型云英岩型阶段、钨锡矿石英脉阶段、石英脉硫化物阶段。更多还原

【Abstract】 Baigan Lake tungsten-tin ore field,located in Xinjiang province, contains four deposits,Kekekaerde,Baigan Lake deposit, Bashierxi and the Awar.All deposits mineralization show similar geology character as multiple type in single deposit area and related to stratigraphy, structure and magmatism.We can defined structure as pre-ore-forming stage, ore-forming stage and post-ore-forming stage,the later of which always inherit,replace,superpose the former stucture.Ore-forimg stage took place in Caledonian. Different scale level can also be recognized as regional scale,ore-field scale and orebody scale. Regional scale Baigan lake fault play a role as controlling the distribution of stratum and intrusions,both are close with mineralization. The Secondary faults of Baigan lake fault and intrusive contact structure zone control Ore-hosting structure,including parallel and echelon shape.Fluid inclusions in the three stage quartz can be divided into five types:G-L two phases, G-L-D three phases,CO2or water single phase,CO2-H2O three phases,and CO2-H2O-NaCl four phases. The first two are the main types in stage one quartz. Ore-forming satge quartz vein can be divided in two period and the first period was major W-Sn precipitating period and have all the five types of fluid inclusion.post-mineralization quartz contains mainly G-L two phases type. Ramman analysis results show that the liquid composition contains H2O and CO2while the gaseous composition contains minor CH4and N2as well. H-O isotopic composition of fluid inclusions in the three type veins indicate that ore-forming fluid is a mixture of magmatic water,atmospheric water and metamorphic water.Study on petrographic, microthermometry,and H-O isotopic analysis impy fluid immiscibility and fluid mixing, which may play a significant role for tungsten precipitation.Composite body intrusive this deposit area.Moyite and adamellite emplaced in north-eastern area show as composite body which have similar contemporary and geochemical characteristic.Zircon U-Pb age obtained by SIMS technique are422±3Ma and421±4Ma respectively,indicating mid-late Silurian.40Ar/39Ar plateau age of muscovite from ore-forming alternative granite dike is411.7±2.6Ma while age muscovite from W-Sn quartz vein is412.8±2.4Ma,indicating that Magmatism and mineralization events is continuous.Composite pluton has the characteristics of the A-type granites,diagenetic background stretch stress field of late orogenic environment. Pluton which is rich in ore-forming elements is not noly the parent rock of Baigan Lake tungsten-tin-polymetallic mineralization, but also white Baigan tungsten polymetallic ore field intothe center of the mine system.Metallogenic model can be described as sedimentary-metamorphic deformed mineralized period-agmatism hydrothermal mineralization period-supergenesis period. Magmatism hydrothermal ore-forming period was futher divided into veinlets formative stage, stratiform tungsten-tin ore body formation stage and W-Sn quartz vein ore body formation stage.更多还原