云南保山核桃坪铅锌矿床矿化分带模式研究

【作者】 李敬；

【导师】 薛传东；

【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2011， 硕士

【摘要】 保山地块夹持于怒江断裂带和澜沧江断裂带之间,是一个铁、铜、金、银、铅、锌多金属矿化集中区。核桃坪铅锌矿床是发育于保山地块内的一个大型铅锌铜多金属矿床,矿体主要呈脉状、似层状赋存于北北东向核桃坪复式背斜的东翼近核部的上寒武统核桃坪组和沙河厂组大理岩化灰岩及矽卡岩中,并严格受近SN向的断裂带及层间破碎带的控制。本文通过大量的立体蚀变—岩相填图和资料收集,在分析矿床地质特征的基础上,选取V,矿体(群)为研究对象,分六个中段对矿(化)体、蚀变岩及其矿物组合、成分、生成顺序、空间分布特征等进行系统的甄别研究,结合流体的物理化学性质的分析,探讨建立了矿床的矿化分带模式。本研究主要取得以下成果和认识：1、根据矿物的生成顺序、脉体穿插和地质体空间关系等特点,将核桃坪铅锌矿床成矿作用分为矽卡岩—热液硫化物成矿期和表生期。区内热液蚀变矿化较为复杂,明显具有多阶段性活动特点,矽卡岩—热液硫化物成矿期可细分为6个阶段,即：(Ⅰ)干矽卡岩阶段、(Ⅱ)湿矽卡岩阶段、(Ⅲ)石英—黄铁矿—黄铜矿—闪锌矿阶段、(Ⅳ)石英—闪锌矿—方铅矿—黄铜矿阶段、(Ⅴ)石英—碳酸盐—闪锌矿—方铅矿阶段和(Ⅵ)碳酸盐阶段。其中,Ⅲ、Ⅳ、Ⅴ三个阶段是铅锌多金属成矿的主要阶段。2、矿床具有明显的水平和垂直蚀变矿化分带特征,水平分带为中心条带对称结构。自矿体中心向围岩、自下而上,可以分为矽卡岩—黄铁矿化带、矽卡岩—铅锌矿化带、碳酸盐—石英—矽卡岩化带、碳酸盐—绿泥石化带,对应的矿石矿物组合依次为方铅矿—闪锌矿组合、闪锌矿—方铅矿组合、闪锌矿—黄铜矿—方铅矿组合和黄铁矿—黄铜矿—闪锌矿—方铅矿组合,矿石矿物组合和结构构造类型变复杂。3、核桃坪铅锌矿成矿流体的包裹体岩相学、显微测温及包裹体成分分析结果表明,从早期干矽卡岩阶段至晚期碳酸盐阶段的整个成矿流体演化过程中,流体温度、盐度、压力、密度总体上呈现出逐渐下降的趋势,闪锌矿大量沉淀的温度为190～210℃,晚阶段流体比早阶段显示更为还原的环境条件。4、根据蚀变矿物组合及矿化分带特征,结合流体的物理化学性质,建立了该矿床的蚀变矿化分带模式。该蚀变矿化分带模式在西南“三江”多金属成矿域具有普遍意义,也有助于对核桃坪铅锌矿床成矿流体运聚和富集成矿的深入理解。5、该矿床属岩浆期后热液充填交代成因,为远端脉型矽卡岩型(类矽卡岩型)铅锌铜多金属矿床,地层岩性、断裂发育特征及流体运移的多阶段性,是蚀变矿化分带的关键控制因素。根据目前矿体揭露情况来看,其深部仍有很大的找矿前景,并存在接触交代矽卡岩型和斑岩型矿床的成矿潜力。更多还原

【Abstract】 The Baoshan block is a Fe, Cu, Au, Ag, Pb, Zn polymetallic metallogenic belt, lies between Nujiang and Lancang jiang fault zones. The Hetaoping as a large Pb-Zn-Cu polymetallic deposit, where in the Baoshan block, and whose ore bodies were stratiform or stratoid, hosted in the group of limestone and skarn of the Hetaoping group and Shachanghe group, on the east of NNE anticline, in upper Cambrian, and, was strictly controlled by nearly SN fault zone and fractured zones of interbedded faults. This paper study of the mineral assemblage, chemical composition, succession of the minerals formed, distribution feature, and, based on the analysis of the geological characteristics and the study of the altered rocks and lithofacies mapping of the V1 ore bodies. The study discussed the mode of the deposit’s mineralization zoning, association with the physical chemistry properties of the fluid. Some achievements have been getting as below.1.Based on the generation sequence and interpenetrating relationship of mineral, The author proposed that the mineralization can be divided into skarn stage, hydrothermal sulfide stage and supergene stage. Hydrothermal alteration of the ore district is complex and characterized with multi-stage activities, which is reflected mainly in skarn-hydrothermal sulfide mineralization. six mineralization stages can be distinguished:(Ⅰ) dry skarn stage, (Ⅱ) wet skarn stage, (Ⅲ) skarn-quartz-pyrite-chalcopyrite-sphalerite stage, (Ⅳ) quartz-sphalerite-galena-chalcopyrite stage (Ⅴ) quartz-carbonate-sphalerite-galena stage and (VI) carbonate stage. The stage(III), (Ⅳ) and (Ⅴ) are the main mineraliztion stage of lead-zinc polymetallic2.The deposit has obvious horizontal and vertical alteration banding phenomenon. Horizontal zone has center-symmetrical structure. There are 4 zones form the center of the bodies to the wall rock, skarn-pyrite zone, skarn-Pb-Zn zone, carbonate-Quartz-skarn zone, carbonate-chlorite zone. The zones according to the mineral combination can be divided as, galena-sphalerite zone, sphalerite-galena zone, sphalerite-chalcopyrite-galena zone and pyrite-chalcopyrite-sphalerite-galena zone. The characteristics of the alteration zoning Vertically from deep to the surface is same with the that of horizontal.3.The analysis results shows that the fluid temperature, salinity, pressure, and density appears on the whole is descendant trend, from skarn stage to carbonate phase, according to fluid inclusions petrography, temperature measuring, and inclusion composition. The precipitation temperature of larger amounts sphalerite was 190～210℃. Inclusions composition show that the late phase of of fluid is more reduction than that of the early stage. It shows that the late phase is more reducing than the early stage by inclusion.4.The model of alteration and metallogenesis zoning was established on the basis of the mineral assemblages and mineralization zoning characteristics, combined with the physical and chemical properties of the fluid. It has the universal significance of the model in the Southwest "three rivers" polymetallic ore field, and, it’s could help to understand the ore-forming fluid migration and mineralization of the Hetaoping Pb-Zn deposit.5.The genesis of the deposit belongs to a postmagmatic hydrothermal metasomatic type, as vein skarn (similar skarn type) Pb-Zn-Cu polymetallic deposit. It is a multi-stage by lithology, fracture characteristics and development of fluid migration. There is a good prospects to finding the depth mineral resources, and there is contact metasomatic skarn and porphyry mineralization potential, directed against the situation of the ore body.更多还原