新疆北山地区大青山金矿床成因、控矿因素与找矿方向

发布时间：2018-05-15 15:41

  本文选题：矿床成因 + 控矿因素　； 参考：《中国地质大学(北京)》2017年博士论文

【摘要】：大青山金矿床位于塔里木板块东北缘,北山古生代裂谷系南亚带西段,处于大青山-红十井-白山金、铜、铁、盐类成矿带上。长期以来,针对大青山金矿床的研究多集中于矿床地质特征,在成矿年代学、成矿流体性质和来源以及矿床成因等方面几乎处于空白,这在一定程度上制约了该矿床及成矿带中其他类似金矿床的找矿进程。鉴于此,本文在大量野外地质工作的基础上,综合运用构造地质学、岩石学、矿物学、矿床学、矿床地球化学、流体包裹体地质学、同位素地质学等多学科理论和方法,在查明大青山金矿床成因和控矿因素的基础上,总结了成矿规律,指明了下一步找矿方向。矿床产于下石炭统红柳园组变质岩中,其原岩为一套杂砂岩、亚杂砂岩和长石砂岩夹粘土岩。矿区内识别出3期变质变形作用,分别对应3期石英脉,其中第2期为含金石英脉矿体。金矿体受库鲁克脆韧性-韧性剪切带及其次级断裂控制,总体走向NEE。矿石类型分为石英脉型和蚀变岩型。矿石中金属矿物有自然金、毒砂、黄铁矿、黄铜矿、方铅矿、闪锌矿、磁黄铁矿、铜蓝及赤铁矿等;非金属矿物包括石英、绢云母、方解石、绿泥石、铁白云石、菱铁矿及钠长石等。围岩蚀变以硅化、绢云母化、黄铁矿化、毒砂化、绿泥石化、钠长石化和碳酸盐化为主。流体包裹体及同位素研究表明,成矿期石英脉中主要赋存气液两相盐水包裹体和CO_2-H_2O三相包裹体。成矿流体总体属于中高温(205~423℃)、低盐度(0.22~8.80%NaCl_(eqv))、中等密度(0.55~0.85 g/cm~3)的H_2O-CO_2±CH_4±N_2体系。成矿流体来源主要为变质水,并与围岩发生了水-岩反应。流体不混溶作用可能是该矿床中金等成矿物质大量沉淀的原因。成矿作用发生于早二叠世(274 Ma),与赋矿地层中的变质增生锆石形成时代(269.6 Ma)一致。成矿物质可能主要来源于毗邻的三峰山VMS铜矿床及其赋矿玄武岩。大青山金矿床属于海西期末区域变质过程中形成的造山型金矿床。综合研究表明,大青山金矿床受地层、构造、蚀变围岩等因素控制,在此基础上,探讨了构造-成矿作用过程,建立了矿床的成因模式,认为区内4号、37号、41号、68号、104号、109号及115号石英脉具有较好的找矿前景。
[Abstract]:The Daqingshan gold deposit is located in the northeast margin of Tarim plate and in the western part of the South Asian belt of the Paleozoic rift system of the Beishan Mountains. It is located in the Daqingshan-Hongshijing-Baishan gold, copper, iron and salt metallogenic belt. For a long time, the study of Daqingshan gold deposit is mostly focused on the geological characteristics of the deposit, and is almost blank in the aspects of metallogenic chronology, ore-forming fluid nature and origin, and the genesis of the deposit, etc. To some extent, this restricts the prospecting process of the deposit and other similar gold deposits in the metallogenic belt. In view of this, on the basis of a great deal of field geological work, this paper synthetically applies the theories and methods of structural geology, petrology, mineralogy, deposit geochemistry, fluid inclusion geology, isotope geology and so on. On the basis of finding out the genesis and ore-controlling factors of Daqingshan gold deposit, the metallogenic law is summarized and the next prospecting direction is pointed out. The deposit occurs in the metamorphic rocks of Hongliuyuan formation of Lower Carboniferous. The primary rocks are a set of complex sandstone, sub-complex sandstone and feldspathic sandstone intercalated with clay rock. Three stages of metamorphic deformation have been identified in the mining area, corresponding to three periods of quartz veins respectively, and the second stage is the orebody of gold-bearing quartz veins. The gold orebody is controlled by the Kuluk ductile shear zone and its secondary faults, and the overall strike is NEE. The ore type is divided into quartz vein type and altered rock type. The metallic minerals in the ore are natural gold, arsenopyrite, pyrite, chalcopyrite, galena, sphalerite, pyrrhotite, copper blue and hematite, etc.; Non-metallic minerals include quartz, sericite, calcite, chlorite, iron dolomite, etc. Siderite and albite, etc. The main alteration of surrounding rock is silicification, sericite, pyrite, arsenopyrite, green mud petrification, albite and carbonization. The study of fluid inclusions and isotopes shows that there are mainly gas-liquid two-phase brine inclusions and CO_2-H_2O three-phase inclusions in quartz veins during the metallogenic period. The ore-forming fluid generally belongs to the H_2O-CO_2 卤CH_4 卤N2 system of moderate and high temperature of 205 ~ 423 鈩，

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