白金台子金矿床地质特征及垂直分带规律

发布时间：2018-04-15 08:39

  本文选题：石英脉-蚀变岩型金矿 + 垂直分带　； 参考：《成都理工大学》2015年硕士论文

【摘要】：大渡河金成矿带位于康滇地轴南北向构造带北端,鲜水河、龙门山与攀西裂谷所构成的三叉裂谷交会形成的特殊构造部位,是我国西南地区重要的一个金成矿带。该区域上受北部的华北板块、东部的扬子板块及西部的印度板块这3个不同方位的板块相互之间的俯冲、碰撞及陆内会聚而形成一个倒三角,区内构造复杂,褶皱、断裂十分发育,受南北向与东西向双向挤压。在板块俯冲、碰撞过程中发育大量的韧性剪切带,而许多韧性带中分布着大量的长英质脉、石英脉。正是这些大型韧性推覆构造形成大量层内与层间滑脱的储矿空间,变质变形作用强烈,为本区域金成矿创造了极为有利的地质背景和成矿条件。在该区域南北长60km、东西宽几千米至30km范围内,已发现岩金矿床(点)60余处,构成了著名的康定大渡河“金谷”。白金台子矿床是该区域内比较具有代表性的矿床,它位于康定县境内,属于三合乡管辖,矿体产于康定杂岩推覆体内部。自从该矿床开采利用以来,对矿床深部是否有矿尚未进行探讨。本文选择该矿床作为研究对象,重点研究该矿床的垂直分带规律,探讨矿床成因,为深部预测性找矿提供参考。本文主要研究内容包括:区域地质背景、区域岩浆岩特征、矿床地质特征、矿床地球化学特征、元素垂直分带规律等。通过以上研究,取得如下成果和认识:(1)矿床围岩主要为咱里组混合花岗岩。其特点为,轻稀土较重稀土富集,内部分馏明显,弱负铕异常,这种特征是在地壳增厚条件下,为硅铝层重熔成因的异地型岩浆侵入花岗岩所特有的稀土元素分布特征。(2)矿体的产状在空间上产状变化为上缓下陡,呈膝状,矿床的赋矿岩石主要为花岗岩,主要载金矿物为黄铁矿和石英。(3)矿床围岩蚀变类型主要有硅化、黄铁矿化、绢云母化、绿泥石化、碳酸盐化、帘石化等。这些围岩蚀变产物具有明显的垂直分带现象。在矿床上部,主要以硅化、黄铁矿化为主;在床下部,主要以硅化、黄铁矿化、黄铜矿化、方铅矿矿化、碳酸盐化为主。(4)矿床中元素在垂直空间上呈现一定的分带性:在矿床下部石英的微量元素含量要比上部的高,即说明上部的石英要较纯些;黄铁矿中Cu、Pb、Bi含量及Pb/Sb从上往下逐渐升高,而Li、Co、Ni、Sr、Mo、Ba,Co/Ni明显降低;石英中Zn、Pb、Ni、Ba、Sb、Sr含量及Pb/Sb自上往下逐渐升高,而Cu、Li、Sr、Mo,Co/Ni和Mo/Bi明显降低,Be、Cd、W、Bi等元素含量变化不大。(5)白金台子石英脉中黄铁矿硫同位素分析结果δ34S值为0.7‰~1.1‰,均值为0.97‰,均一化程度较高,分布集中,接近陨石硫,具明显的岩浆硫或幔源硫同位素组成特点。说明矿体中硫来源于深部岩浆,预示着金成矿与岩浆热液有密切的关系。(6)矿区内基性辉绿岩脉与含金石英紧密相伴。辉绿岩的锆石U-Pb年龄为425.3士3.1Ma,而含矿石英的形成年龄为32.4~43Ma,平均为37.7Ma。二者形成时代明显不一致,成矿时代大大晚于基性脉岩的形成。但这些基性岩脉(体)的出现指示了其所在位置曾发生过深达下地壳或上地幔的拉张作用,说明大渡河断裂是深达下地壳或上地幔的深大断裂。在区域性拉张的环境下,不仅有利于深部地壳或上地幔的基性岩浆的上升侵位,同样有利于深部热液流体的运移。
[Abstract]:The Dadu River gold metallogenic belt is located in the Kangdian axis north-south tectonic belt at the north end, fresh water river, special tectonic location of Longmen mountain and the Panxi rift formed by the intersection of trigeminal rift formation, is a Southwest important gold metallogenic belts in China. The area affected by the north of the North China plate, the eastern part of the Yangtze plate and the western India plate of the 3 different directions between plate subduction, collision and intracontinental convergence and the formation of an inverted triangle area, complex structures, folds, faults are well developed, the north-south and east-west two-way extrusion. In the subduction zone, ductile shear zone for the development of a large number of collision process, and a lot of ductile zone distributed in felsic veins, a quartz vein. It is these large ductile nappe structure formed in a large number of coal storage space layer and interlayer slip, strong metamorphism and deformation, the regional gold mineralization has created extremely favorable. Background and metallogenic conditions in the region. 60km long from north to south, east-west width of several thousand meters to the range of 30km, has been found in rock gold deposits (points) 60, a famous Kangding Dadu River "Valley". The platinum deposit is the region table more representative of the deposit, which is located in Kangding County three, belonging to the township jurisdiction, ore produced in the Kangding complex nappe. Since the deposit exploitation is not discussed in deep ore deposit. The ore deposit as the research object, focuses on the vertical zoning of the deposit, the genesis for deep forecast for mine for reference. The main contents of this paper include: regional geological background, regional magmatite features, geological characteristics, geochemical characteristics of the deposit, the elements of vertical zoning. Through the above research, the following results and understanding: (1) the main rock deposit I was in group. The characteristics of mixed granite, light rare earth heavy REE enrichment, internal fractionation significantly, weak negative Eu anomaly, which is characterized by thickening of the crust under the condition of invasion of rare earth elements peculiar to different type granite magma remelting sial origin distribution. (2) the occurrence of orebody the shape change in space to slow down a steep, geniculate, ore bearing rock deposits are mainly granite, the main gold bearing minerals are pyrite and quartz. (3) deposit types of wall rock alteration includes silicification, pyritization, sericitization, chloritization and epidotization carbonate, etc. these. The wall rock alteration product has obvious vertical zonation phenomenon. In the upper part of the deposit, mainly silicification, pyritization; in the lower part of the bed, mainly silicification, pyrite, chalcopyrite, galena mineralization, carbonate deposits. (4) in element in the vertical space presents certain points 甯︽，

本文编号：1753397