吉林靖宇常发沟金铜矿床地质特征及矿化富集规律

发布时间：2018-05-11 09:13

本文选题：斑岩型矿床 + 矿床地质　；参考：《吉林大学》2015年硕士论文

【摘要】：常发沟金铜矿床位于吉林省靖宇县，是吉黑东部典型的斑岩型金铜矿床。大地构造位置位于华北地台北缘东段高级变质区内，处于敦化-密山断裂以南，属于王家店—天合兴多金属成矿带。矿区地层出露简单，主要有太古宙鞍山群和第四系松散砂砾石层。矿区内岩浆岩分布广泛，分布面积约占矿区面积的1/2，以侵入岩为主，零星分布少量脉岩。按侵入时间从老到新主要侵入太古代花岗岩（2585.4±7.4Ma）与闪长玢岩（2531.5±8.4Ma），晚三叠世花岗斑岩（218±1.4Ma）及早白垩世石英斑岩（118.11±0.92Ma）。其中早白垩世石英斑岩是常发沟金铜矿床的重要含矿岩体，岩石地球化学研究表明石英斑岩体为富硅、富铝的高钾钙碱性系列-钾玄岩序列岩石，形成于太平洋板块俯冲于欧亚大陆之下的弧后伸展环境。常发沟金铜矿区圈定了3个矿段—I矿段、II矿段及III矿段。矿体均为隐伏矿体，围岩多为石英斑岩。本次研究发现金属矿物主要为黄铜矿、辉钼矿等。矿石构造主要有团块状构造、浸染状构造及脉状构造。矿体围岩蚀变具有典型的面型蚀变特征，由内向外依次发育钾质蚀变带（钾化）—似千枚岩化蚀变带（硅化、绢云母化）—泥质蚀变带（高岭土化）—青磐岩化带（碳酸盐化、绿泥石化、绿帘石化）。大酱缸矿区位于常发沟矿区的西部，本次研究利用槽探工程进行揭露，新发现多条金矿化体，以典型的黄铁绢英岩为主，受构造控制明显。矿石矿物以细粒的黄铁矿为主，另含少量的黄铜矿、方铅矿、闪锌矿、磁铁矿等，围岩蚀变类型主要为硅化、碳酸盐化等。流体包裹体研究发现，矿区发育多种类型的包裹体。显微测温结果表明该区成矿流体系统从早期到晚期的演化过程中，成矿流体的温度、盐度、密度等系数呈逐渐降低的趋势。常发沟矿床成矿流体显示中高温、中高盐度的特点，通过计算得出矿床的成矿压力为3～22MPa，成矿深度为0.3～2.2km。大酱缸矿区的成矿流体具有中温、低盐度、低密度的特点。硫同位素研究表明成矿元素主要来自于地幔岩浆，有部分壳源岩浆的混入。通过含矿岩体的年龄测定，可以初步判断常发沟金铜矿床的成矿年龄在118Ma左右，属于燕山晚期。矿床形成构造背景为太平洋板块俯冲后的弧后伸展环境中。通过对常发沟金铜矿床与国内外典型斑岩型矿床对比分析，认为常发沟金铜矿床成因类型应定为斑岩型矿床。根据大酱缸金矿床的矿床地质及成矿物理化学条件的特征研究，初步确定其成因类型为中温热液脉型金矿床。矿化富集规律研究发现，矿体整体赋存在石英斑岩体内，而且与面型蚀变带相对应地呈现矿化分带，垂向上浅部主要发育方铅矿化与闪锌矿化，向深部发育辉钼矿化及黄铜矿化，再向内部发育黄铁矿化与磁黄铁矿，而在整个矿区范围内，由于受到了北西向构造的破坏作用，整体上呈现出西部相对富集铅锌矿化及褐铁矿矿化，中部黄铜矿化、辉钼矿化富集。因此，研究区中部为黄铜矿与辉钼矿的重点富集区域，而北西部可能富集形成铅锌矿体。此外，西部的大酱缸矿区金成矿潜力很好，有待进一步勘查研究。该矿床受北西向断裂构造控制明显，因此建议今后以断裂构造为主攻方向，沿含矿构造追索矿体，，并重视与理清成矿后构造对矿体错断、位移的影响。
[Abstract]:The Changdu gou gold - copper deposit is located in Jingyu County , Jilin Province . It is a typical porphyry type gold - copper deposit in the eastern part of Jilin Province . Its tectonic position is located in the high - grade metamorphic zone of the eastern part of the northern margin of the northern margin of North China . It is located south of the Dunhua - Mashan fault , and belongs to the multi - metal metallogenic belt of Wangjidian - Tianxing .

Early Cretaceous quartz porphyry is an important ore - bearing rock mass in the Changgou gold - copper deposit , and the late Triassic granodiorite is an important ore - bearing rock mass of the Changgou gold - copper deposit .

In this paper , three segments - I , II and III are trapped in the Au - Cu deposit . The ore bodies are hidden ore bodies , and the surrounding rocks are mostly quartz porphyry . The study shows that the metal minerals are mainly pyrite , molybdates and the like . The ore structures mainly include mass structure , disseminated structure and vein - like structure . Large - sized soy - jar mining area is located in the west of Changfa Mine , which is exposed by the trench exploration project . It has been newly discovered that multiple gold mineralization bodies are mainly composed of fine pyrite , and the structure control is obvious . The ore minerals mainly include fine pyrite , and a small amount of pyrite , galena , sphalerite , magnetite and so on . The type of alteration of surrounding rock is mainly silicification , carbonation and so on .

The results show that the ore - forming pressure of the ore - forming fluid is 3 - 22MPa and the ore - forming depth is 0.3 - 2.2km .

By the age determination of the ore - bearing rock mass , it is possible to preliminarily determine the ore - forming age of the Changfa gold - copper deposit at about 118Ma , which belongs to the late Yanshan . The formation tectonic background of the deposit is in the post - arc extension environment after subduction of the Pacific plate . By comparing the characteristics of the Changfa gold - copper deposit and the typical porphyry type deposit at home and abroad , the authors believe that the genesis type of the Changfa gold - copper deposit is the medium - temperature hydrothermal vein type gold deposit .

It is found that the whole ore body is distributed in the quartz porphyry body , and the mineralization zoning is presented to the surface type alteration zone . The main development of the vertical shallow part is mainly galena and sphalerite mineralization .

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51;P618.41

【参考文献】