黑龙江宝山铜钼多金属矿床地质、地球化学特征及成因探讨

发布时间：2018-04-09 17:38

  本文选题：成矿流体　切入点：岩石地球化学　出处：《中国地质大学(北京)》2015年硕士论文

【摘要】：宝山铜钼多金属矿床位于小兴安岭—张广才岭铁-铜-钼-金多金属成矿带北端,是近年发现的研究程度较低的矽卡岩型矿床。本文在野外地质调查的基础上,结合室内研究(薄片、光薄片、地球化学及流体包裹体),确定矿床地质特征、地球化学特征,厘定了矿床成因。宝山铜钼多金属矿床产于花岗闪长岩与下寒武统铅山组大理岩的内外接触带,显示出典型的矽卡岩型矿床特征。矿区发育2期侵入岩,早期片麻状花岗岩属弱过铝质、高硅、高钾钙碱性系列的俯冲型I型花岗岩;后期花岗闪长岩、正长花岗岩属准铝质-弱过铝质、高硅、钾玄岩-高钾钙碱性系列的同碰撞I型花岗岩,与成矿有密切的关系。片麻状花岗岩为俯冲环境,为松嫩-张广才岭地块和佳木斯地块之间陆间洋向西俯冲于松嫩-张广才岭地块之下形成的;花岗闪长岩及正长花岗岩为同碰撞环境,为早三叠世“佳蒙地块”与华北板块北缘东段碰撞的产物。矽卡岩型矿石为主要的矿石类型。矿石构造有浸染状构造、星散状构造、细脉浸染状构造;矿石结构主要有粒状结构、鳞片状结构、共结边结构和固溶体分离结构(乳滴状结构、叶片状结构)等。根据野外及室内镜下矿物共生组合关系,将矿床成矿过程划分为3期4个阶段即矽卡岩期(干矽卡岩阶段Ⅰ、湿矽卡岩阶段Ⅱ)、石英硫化物期(石英-硫化物阶段Ⅲ、碳酸盐阶段Ⅳ)及表生期。宝山铜钼多金属矿床的成矿流体属于中-高温、中-高盐度和中等密度体系,矿床形成于中深成环境。随着成矿作用的进行,成矿流体表现出一定的演化规律,成矿流体包裹体的均一温度、成矿压力、成矿深度呈降低趋势,成矿流体的盐度具有从高盐度向低盐度的演化趋势,成矿流体的密度逐渐增高。流体包裹体岩相学观察结合测温,在石英中可以发现包裹体沸腾的证据,证明矿床金属硫化物的沉淀为流体不混溶(沸腾)作用导致的。宝山铜钼多金属矿床显示出典型的矽卡岩型矿床的特征,表现在控矿因素、矿石类型、矿体特征、围岩蚀变特征、矿物组构、矿物共生组合关系等特征。
[Abstract]:Baoshan copper-molybdenum polymetallic deposit is located at the northern end of the Xiaoxing'anling Zhangguangcailing iron copper-molybdenum gold polymetallic metallogenic belt. It is a skarn type deposit which has been discovered in recent years.On the basis of field geological survey, combined with laboratory studies (thin sheet, light sheet, geochemistry and fluid inclusions), the geological and geochemical characteristics of the deposit are determined, and the genesis of the deposit is determined.Baoshan copper-molybdenum polymetallic deposit occurs in the inner and outer contact zone between granodiorite and lower Cambrian lead-shan marble, which shows the typical skarn type deposit.The intrusive rocks of the second stage are developed in the ore area. The early granitic granites are subducted type I granites of weak peraluminous, high silicon and high potassium calc-alkaline series, while the late granodiorite and syenite are quasi-alumina-weak peraluminous, high-silicon granitic granodiorite.The syncollisional I type granites of high K calc alkaline series are closely related to mineralization.The granodiorite is a subduction environment, formed by a westward subduction of the continental ocean between the Songnen-Zhangguangcailing and Jiamusi massif, and the granodiorite and syenite are in the same collision environment.It is the product of the collision between the early Triassic Jiameng Block and the eastern segment of the North China plate.Skarn type ore is the main ore type.The ore structure includes disseminated structure, scattered structure and vein-like structure, and the ore structure mainly consists of granular structure, scale-like structure, cojunction structure and solid solution separation structure (emulsion dripping structure, blade structure) and so on.According to the mineral symbiotic assemblages in the field and under indoor mirror, the metallogenic process of the deposit can be divided into three stages: skarn stage (dry skarn stage 鈪，

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