内蒙古敖汉旗金厂梁金矿床地球化学特征及成因研究

发布时间：2018-09-15 19:07

【摘要】：内蒙-兴安地块和华北板块北部二者的交汇位置是理想的成矿环境，区内金矿床比较发育，金厂梁金矿床正处在该矿集区内。区内断裂构造极其发育，岩浆活动频繁，成矿条件优越。本文旨在通过对该矿床的区域成矿背景、矿床地质地球化学特征、矿床成因及机制等研究，为该矿床及区域金矿的找矿勘探奠定理论基础。 与金厂梁金矿成矿有关的晚三叠世二长花岗岩岩石化学、地球化学研究表明，该岩体属于高铝、高钾钙碱性系列岩石。在R1-R2构造环境判别图解中，二长花岗岩样品投影点主要落于造山晚期花岗岩区。而花岗岩Ta-Yb构造环境判别图解中，主要位于同碰撞-造山晚期花岗岩区。因此，晚三叠世二长花岗岩是陆-陆碰撞造山晚期产生的“S”型花岗岩。 矿床地质特征研究表明，（含）金矿体赋矿围岩为中太古代乌拉山岩群。该地层主要包括黑云斜长片麻岩、黑云角闪斜长片麻岩、斜长角闪片麻岩以及混合岩化片麻岩，为一套太古代变质岩系。区内断裂较为发育，主要为分为近东西向、北东向。其中，矿区北部发育一条近东西向断裂构造，在二长花岗岩和乌拉山岩群的接触位置，发育构造破碎带，破碎带内可见到硅化、绿泥石化等。矿脉受控于断裂构造，矿体的产出主要分为透镜状、脉状、扁豆状等形态。在石英脉或者硅化围岩内，矿化较为发育。金属矿物主要有黄铜矿、黄铁矿、银金矿、斑铜矿、磁铁矿、辉锑矿，发育有硅化、（黄铁）绢英岩化、碳酸盐化、绿泥石化等围岩蚀变类型，为一套与金成矿有关的中低温热液蚀变。 流体包裹体研究表明，石英中包裹体类型主要为气液两相，气液比通常为10%～30%，多集中在10%～15%之间。成矿流体的盐度范围为1.05～8.14wt%NaCl，密度处在0.856～0.986g/cm3之间，显示出低盐度、低密度的特点。均一温度为138.3～223.2℃，成矿压力5.32～11.1Mpa，成矿深度0.52～1.11Km，具有中低温浅成成矿的特点。 H、O同位素研究表明，含矿热液具有深源特点，主成矿期的成矿流体以岩浆水为主，并含有少量的大气水。S同位素研究表明，成矿物质来源于地幔或地壳深部。 综合研究认为，，金厂梁金矿床为形成于印支期的浅成低温造山型金矿床。
[Abstract]:The intersection position between the Neimeng-Xingan block and the northern part of the North China plate is an ideal metallogenic environment where the gold deposits are relatively developed and the Jinchangliang gold deposit is located in the ore accumulation area. The fault structure in the area is extremely developed, magmatic activity is frequent, and metallogenic conditions are superior. The purpose of this paper is to lay a theoretical foundation for the prospecting and exploration of the deposit and the regional gold deposit through the study of the regional metallogenic background, geological and geochemical characteristics, genesis and mechanism of the deposit. The petrochemistry and geochemistry of the late Triassic granites associated with the mineralization of the Jinchangliang gold deposit indicate that the rock body belongs to a series of rocks of high aluminum and high potassium calc-alkaline series. In the discriminant diagram of R1-R2 tectonic environment, the projection points of the monzomorphic granite samples are mainly located in the late orogenic granite area. In the distinguishing diagram of Ta-Yb tectonic environment of granite, it is mainly located in the area of syncollision-orogenic late granite. Therefore, the late Triassic monzomorphic granites are "S" type granites produced in late continental-continental collision orogenic period. The geological characteristics of the deposit indicate that the host rock of the gold deposit is the middle Archean Wulashan rock group. The strata are mainly composed of black cloud plagioclase gneiss, black cloud hornblende gneiss, plagioclase diorite gneiss and migmatite gneiss, which are a set of Archean metamorphic rocks. The faults in the area are relatively developed, mainly divided into near-E-W and N-E directions. Among them, a near east-west fault structure developed in the north of the mining area. In the contact position of the monzonitic granite and the Wulashan rock group, the tectonic fracture zone is developed, and silicification and greenstone can be seen in the breakage zone. The ore vein is controlled by the fault structure and the orebody is mainly divided into lenticular, vein and lentil forms. In quartz vein or silicified surrounding rock, mineralization is more developed. The main metallic minerals are chalcopyrite, pyrite, silver gold deposit, porphyrite, magnetite, stibnite, and there are silicification, (Huang Tie) sericite, carbonization, green mud petrifaction and other wall rock alteration types. It is a set of medium and low temperature hydrothermal alteration related to gold mineralization. The study of fluid inclusions shows that the inclusions in quartz are mainly gas-liquid two-phase, the gas-liquid ratio is usually 100.30%, and most of the inclusions are between 10% and 15%. The salinity range of ore-forming fluid is 1.05 ~ 8.14 wtNaCl.The density is between 0.856~0.986g/cm3, showing the characteristics of low salinity and low density. The homogenization temperature is 138.3 ~ 223.2 鈩

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