新疆若羌三峰山铜矿床成因、成矿规律与找矿方向

发布时间：2018-01-19 23:10

  本文关键词： 矿床成因 成矿规律 找矿方向 三峰山铜矿床 北山地区 新疆　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：三峰山铜矿床位于塔里木板块东北缘的北山造山带南部地区,产于石炭纪变质火山-沉积岩系中。近年来,前人主要针对该矿床的地质特征进行了初步研究,对于成矿背景,矿床成因和成矿规律等方面尚未开展详细的研究工作,很大程度上制约了矿体深部与外围的找矿进程。本文在详细野外地质调查基础上,系统研究了三峰山铜矿床的赋矿岩系与矿化特征、成矿流体地球化学、同位素地球化学和成岩成矿年代学等,厘定了矿床的成矿地质背景与矿床成因类型,总结了成矿规律,为矿区找矿勘查工作提供了依据。矿床产于下石炭统红柳园组下段,含矿岩性为浅变质玄武岩和少量绿泥石-绢云母片岩。赋矿玄武岩地球化学特征显示为一套钠质拉斑玄武岩,具有较为平坦的稀土配分模式,无明显高场强元素亏损,Ti/V和Th/Nb值较低。岩浆主要来源于亏损的软流圈地幔大程度部分熔融,并受到了俯冲板片流体的交代影响,形成于古亚洲洋南向俯冲背景下的弧前环境。矿体多呈似层状、扁豆状或透镜状展布,与赋矿地层产状一致。原生矿石类型包括纹层状、角砾状、条带状、块状和浸染状矿石,金属矿物以黄铁矿、黄铜矿和闪锌矿为主。围岩蚀变包括硅化、绿泥石化、绿帘石化、绢云母化和碳酸盐化等,呈带状分布,下盘蚀变相对上盘更加强烈,蚀变过程中MgO和Fe2O3T大量迁入、Na2O迁出,代表了斜长石、钠长石等矿物的分解和绿泥石、黄铁矿的形成,这一过程与成矿关系最为密切。矿区广泛分布含铁锰硅质岩,呈条带状、块状或角砾状与硫化物矿石共生,地球化学特征显示为热水沉积成因,形成于大洋中脊环境。矿床的形成演化主要经历了同生沉积期、变质改造-热液叠加期以及表生期共3个时期。流体包裹体与同位素研究表明,成矿物质主要来自幔源岩浆,可能通过火山脱气或海水热液在循环过程中从赋矿玄武岩中淋滤而来。成矿流体属于中高温(182℃~360℃)、低盐度(0.7%~4.0%)的H2O-NaCl体系,流体来源可能为下渗的海水,岩浆流体对成矿贡献相对较少。矿床的形成时代为早石炭世(353Ma),与赋矿玄武岩喷发时间(350 Ma)较为一致。综合研究认为,三峰山铜矿床为典型的塞浦路斯型火山喷流块状硫化物(VMS)矿床,形成于早石炭世北山造山带的弧前环境。矿床的形成及产出受拉张性构造背景、赋矿火山岩及同生断裂构造等因素控制。在此基础上,总结了矿床形成机制及在成矿时空背景、含矿岩系、矿化分带和围岩蚀变等方面的规律,确定了找矿标志,并指出了下一步找矿方向。
[Abstract]:The Sanfengshan copper deposit is located in the southern part of the Beishan orogenic belt on the northeast margin of the Tarim plate and occurs in the Carboniferous metamorphic volcano-sedimentary rock series. For the metallogenic background, ore deposit genesis and metallogenic law and other aspects have not been carried out detailed research work, to a large extent restricted the orebody deep and peripheral prospecting process. This paper on the basis of detailed field geological survey. The ore-bearing rock series and mineralization characteristics, ore-forming fluid geochemistry, isotopic geochemistry and diagenetic metallogenic chronology of the Sanfengshan copper deposit are systematically studied, and the metallogenic geological background and genetic types of the deposit are determined. The metallogenic regularity is summarized, which provides the basis for the prospecting and exploration of the ore area. The deposit occurs in the lower member of Hongliuyuan formation of Lower Carboniferous. The ore-bearing basalts are of shallow metamorphic basalt and a small amount of chlorite sericite schist. The geochemical characteristics of ore-bearing basalt show a set of sodium tholeiite with a flat REE distribution model. The magma is mainly derived from the depleted asthenospheric mantle to a large extent and is affected by the metasomatism of subduction plate fluids. The orebodies are stratiform, lentil or lentil like, consistent with ore-bearing strata. The primary ore types include lamellar, breccia and banded. The main metallic minerals are pyrite, chalcopyrite and sphalerite. The wall rock alteration includes silicification, green mud, green curtain, sericite and carbonation, etc. During the process of alteration, MgO and Fe2O3T migrated in and out of Na2O, representing the decomposition of plagioclase, albite and the formation of chlorite and pyrite. This process is most closely related to metallogeny. Ferromanganese siliceous rocks are widely distributed in the mining area, which are banded, massive or breccia associated with sulphide ores, and geochemical characteristics show hydrothermal sedimentary origin. It was formed in the middle oceanic ridge environment. The formation and evolution of the deposit mainly experienced three periods: synsedimentary period, metamorphic metamorphic hydrothermal superposition period and superposition period. The fluid inclusions and isotopes were studied. The ore-forming material mainly comes from mantle-derived magma and may be leached from the ore-bearing basalt during the circulation by volcanic degassing or seawater hydrothermal solution. The ore-forming fluid belongs to mid-high temperature (182 鈩，

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