内蒙古乌拉特中旗图古日格金及铜镍硫化物矿床地质特征及成矿模式研究

发布时间：2018-06-12 14:09

本文选题：矿床地质特征 + 矿床成因　；参考：《吉林大学》2017年硕士论文

【摘要】：图古日格金矿位于内蒙古西部乌拉特中旗,大地构造位置位于华北板块北缘,中亚造山带之上,兴蒙造山带西段。在早古生代,研究区处于古亚洲洋俯冲增生阶段,随着古亚洲洋在晚古生代的闭合消亡,在二叠纪进入了由挤压转换为伸展构造背景的后碰撞伸展阶段。矿区出露的地层主要为下元古界宝音图群上段和第四系。矿区断裂构造发育,金矿脉整体受北西向脆性断裂控制。区内岩浆岩较发育,从酸性岩到基性岩均有出露。测年结果显示中二叠世石英闪长岩形成最晚,年龄为266±2Ma。研究认为其中早二叠世似斑状二长花岗岩和石英闪长岩与金矿化关系密切,中二叠世辉石岩和角闪辉长岩与铜镍矿化关系密切。结合区域资料及构造判别图解认为石英闪长岩为区域后碰撞伸展构造背景条件下的岩浆活动产物。金矿体整体以脉状的形态呈北西-南东向分布,矿体的矿化类型以含矿石英脉型为主,其次还有破碎蚀变岩型。矿石结构主要有不等粒结构、包含结构、固溶体分离结构、交代环边结构、碎裂结构。矿石构造主要为脉状构造和稀疏浸染状构造。矿石矿物主要有黄铁矿、黄铜矿、方铅矿、闪锌矿和自然金,还有少量的碲金矿、黝铜矿和铜蓝等。围岩蚀变类型主要有钾化、硅化、黄铁绢英岩化、绿泥石化、绿帘石化、绢云母化、碳酸盐化等,其中硅化、黄铁绢英岩化与金矿化关系最为密切。根据矿体野外地质特征,镜下光薄片中矿物的结构构造、矿物之间的穿插关系、矿物组合及生成顺序,可将热液成矿期划分为四个成矿阶段:石英—铁白云石阶段(Ⅰ)、石英—明金—黄铁矿阶段(Ⅱ)、石英—金—多金属硫化物阶段(Ⅲ)和石英-碳酸岩阶段(Ⅳ),其中第Ⅱ与第Ⅲ阶段为金主成矿阶段。该矿区发育大量的铁白云石和明金,其中铁白云石为成矿早阶段的产物,反映一种贫s2-氧化程度较高的环境。针对成矿早阶段的铁白云石,成矿主阶段和晚阶段的石英进行流体包裹体研究测试分析,结果表明,金矿成矿流体为co2-h2o-nacl体系,在成矿过程中发生明显的流体不混溶作用。三个阶段的均一温度峰值分别为320~340℃,240~280℃和240~250℃;盐度峰值分别为8~9wt%nacl.eqv,4~7wt%nacl.eqv和1~2wt%nacl.eqv;密度峰值分别为0.74~0.78g/cm3,0.84~0.88g/cm3和0.92~1.00g/cm3;具有中温,低盐度,低密度的特征。估算主成矿阶段成矿压力为70~114mpa,成矿深度为6.78~8.86km,具有中成深度的特点。氢、氧、硫同位素测试结果表明,成矿流体主要为地幔初生水,后期有大气降水的加入,成矿物质主要来自地幔。综上,本文认为图古日格金矿床的成因类型为中成造山型金矿床。系统总结了金矿床的矿化富集规律,认为金矿脉严格受nw向和nww向2组形成于同一应力场下的追踪裂隙构造控制,沿2组裂隙的差异追踪形成了2组产状差异明显的矿脉,具体表现为:nw向矿脉追踪nw向裂隙比nww向裂隙更长,nww向矿脉追踪nww向裂隙比nw向裂隙更长;同一组走向的矿脉近似平行排列,矿体在走向上和倾向上的分布具有明显的横向对应规律;矿体分布具有分段富集规律和侧伏规律,nw向的矿脉在nww向部位和缓倾角部位矿化富集;nww向的矿脉在nw向部位和陡倾角部位矿化富集;nw向矿体向nw向侧伏,nww向矿体向nww向侧伏,侧伏角均较小。控矿构造应力分析显示,nw向和nww向两组方向追踪裂隙分别具有左旋压扭和右旋张扭的特点。综上,找矿的重点应该分别在矿脉的侧伏方向上的nw段和nww段的深部位置。在图古日格金矿区出露有数个基性-超基性岩体,并在个别岩体中发现了铜镍矿化。含矿岩体主要为中粗粒辉石岩。辉石岩锆石测年结果显示,这些岩体形成年龄为273.5~274.4ma;构造判别图解显示辉石岩形成于华北板块与南蒙古陆块碰撞后伸展环境;北部含矿岩体具有较高的连续的大范围的正磁异常,反映该区域可能有隐伏岩体存在。综上认为,该区有进一步铜镍找矿潜力。
[Abstract]:Located in the northern margin of the western Inner Mongolia, the tectono tectonic position is located on the northern margin of the North China plate, the Central Asian orogenic belt and the western section of the Xingmeng orogenic belt. In the early Palaeozoic, the study area was in the subduction and proliferation stage of the ancient Asian Ocean. With the closure of the ancient Asian Ocean in the late Paleozoic, the study area was transformed from extrusion to extension during the Permian period. The mining area is mainly in the Upper Proterozoic treasure phoneme group and the quaternary system. The fault structure is developed in the mining area. The gold vein is controlled by the northwestern brittle fracture. The magmatic rocks are more developed in the area, from the acid rock to the basic rock. The results of the dating show that the Permian quartz diorite formed the most. Late Permian porphyritic two feldspar and quartz diorite are closely related to gold mineralization at the age of 266 + 2Ma.. The Middle Permian pyroxenite and hornblende gabbro are closely related to copper nickel mineralization. The gold body is a product of activity. The gold ore body is distributed in the North West to South East in the form of pulse shape. The mineralization type of ore body is mainly composed of ore quartz vein type, followed by fractured altered rock type. The ore structure mainly consists of unequal grain structure, including structure, solid solution separation structure, metasomatism ring edge structure and fractured structure. Ore structure is mainly pulse structure and dilute structure. The ore minerals are mainly pyrite, chalcopyrite, galena, sphalerite and natural gold, and a small amount of tellurite, Tan, sericite, sericite, chlorinization, epidochemistry, sericization, carbonation, etc., in which silicification, silicization and gold mineralization According to the field geological characteristics of the ore body, the structure structure of mineral, the interpenetration relationship between minerals, mineral assemblage and the order of formation can be divided into four metallogenic stages: Quartz - ferric dolomite stage (I), quartz - Ming gold pyrite stage (II), quartz gold polymetallic vulcanization Phase II (III) and quartz carbonatite stage (IV), of which stage II and stage III are the gold main metallogenic stage. A large number of ferric dolomite and Ming gold are developed in this mining area, of which ferric dolomite is the product of early mineralization, reflecting a poor environment with high s2- oxidation degree. The results show that the gold ore-forming fluid is co2-h2o-nacl system, and the fluid immiscibility is obvious during the metallogenic process. The peak average temperature of the three stages is 320~340, 240~280 and 240~250, respectively, and the peak value of the salinity is 8~9wt%nacl.eqv, 4~7wt%nacl.eqv and 1~2wt%nacl.eqv respectively. The peak density is 0.74~0.78g/cm3,0.84~0.88g/cm3 and 0.92~1.00g/cm3 respectively. It has the characteristics of middle temperature, low salinity and low density. It is estimated that the metallogenic pressure of the main metallogenic stage is 70~114mpa, the metallogenic depth is 6.78~8.86km, and it has the characteristics of meso depth. The results of hydrogen, oxygen and sulfur isotope test show that the ore fluid is mainly primary mantle water in the mantle and the later period is large. With the addition of gas and precipitation, the metallogenic material mainly comes from the mantle. In this paper, the genesis type of the gold deposit is considered as a middle orogenic gold deposit. The mineralization enrichment law of the gold deposits is summarized systematically. It is believed that the gold vein is strictly controlled by the traced fracture structure formed under the same stress field in the 2 groups of NW and NWW direction, and the difference along the gap between the 2 groups. 2 groups of veins with distinct differences were traced, which were shown as follows: NW traced NW to the veins longer than NWW in the vein, and NWW traced the vein to the fracture longer than that of NW to the fissure; the ore veins in the same group were approximately parallel, and the ore body in the upward and inclined distribution had a distinct transverse correspondence; the ore body was distributed. NW veins are mineralized and enriched in NWW direction and gently inclined angle, and NWW veins are mineralized and enriched in NW direction and steep dip, NW toward the ore body to NW side, NWW toward the ore body to NWW to the side, and the side volt angle is smaller. The ore control structural stress analysis shows that NW direction and NWW are traced to two groups of directions in the direction of fissure. Not with the characteristics of left-handed and dextral twisting. To sum up, the focus of the prospecting should be in the deep position of the NW and NWW segments in the direction of the vein. There are several basic ultrabasic rocks in the Kutu gold area, and the copper nickel mineralization is found in some rocks. The ore bearing rock is mainly medium coarse granitic pyroxenite. The rock dating shows that the rock formation age is 273.5~274.4ma, and the tectonic discriminative diagram shows that the pyroxenite formed after the collision between the North China plate and the southern Mongolia land block, and the northern ore bearing rock mass has a high continuous large range of positive magnetic anomalies, reflecting the possibility of the existence of concealed rock masses in the region. Copper and nickel prospecting potential.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.2

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