云南保山—龙陵地区西邑铅锌矿床成矿机制及区域找矿标志

发布时间：2018-03-21 21:19

  本文选题：矿床成因　切入点：区域找矿标志　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：云南保山西邑铅锌矿床位于西藏-三江造山系保山地块内,铅锌储量达1.2Mt,为一大型铅锌矿床。近年来,前人主要对该矿床的地质特征进行了初步研究,在矿床地球化学特征、成矿流体性质和来源、成矿物质来源和成矿规律等方面的研究薄弱,矿床成因存在争议,在一定程度上制约了矿区和外围的进一步找矿。本文系统研究了西邑铅锌矿床的地质特征、赋矿岩石地球化学、成矿流体地球化学、同位素地球化学等,厘定了矿床成因类型,提出了成矿模式。并和区域上典型铅锌矿床进行了对比研究,总结了区域矿床的控矿因素,指明了区域找矿标志。矿床分为董家寨、赵寨和鲁图3个矿段,矿体赋存在泥盆系向阳寺组、何元寨组和下石炭统香山组灰岩中,受北东向构造控制,呈似层状、脉状和透镜状产出。矿石中金属矿物主要为方铅矿和闪锌矿,含少量黄铁矿,偶见白铁矿、黄铜矿和毒砂,非金属矿物主要为方解石,含少量重晶石,偶见石英。成矿过程分为I闪锌矿+方铅矿+方解石、II方铅矿+毒砂+方解石±闪锌矿以及III方解石+黄铁矿±重晶石±石英3个热液成矿阶段。流体包裹体和同位素研究表明,成矿流体为低温(100~200℃)、中等盐度(8~20wt%NaCleq)、中等密度(1.0~1.1g/cm3)的H2O-NaCl体系,含有少量CH4,流体来源于盆地卤水。成矿阶段方解石δ13CPDB值变化较小(5.2‰~3.2‰),而δ18OSMOW值变化范围较大(12.5‰~20.0‰),表明成矿流体中碳主要来源于海相碳酸岩的溶解。成矿阶段硫化物的δ34S值集中(0~3‰),重晶石的δ34S值为5~14‰,矿床中硫主要来自地层中的硫酸盐,沉积成岩时期细菌还原作用导致了硫同位素的分馏。铅同位素研究表明,成矿阶段中硫化物与围岩泥盆系何元寨组灰岩中黄铁矿的铅同位素特征相似,具有上地壳来源,表明铅来源于区域上的地层。综合研究认为,西邑铅锌矿床是产在碳酸盐岩地层中受构造控制的盆地热卤水成因的后生热液矿床,在大地构造背景、矿床地质特征、矿床地球化学特征、成矿流体、成矿物质来源等方面类似于MVT铅锌矿床,应为MVT铅锌矿床。在此基础上,建立了矿床的成因模型,并与区域典型矿床对比研究,总结了区域矿床的控矿因素,指明了区域找矿标志。
[Abstract]:The Xiyi Pb-Zn deposit in Baoshan, Yunnan Province, is located in the Baoshan block of Xizang-Sanjiang orogenic system, with a Pb-Zn reserves of 1.2 Mt. It is a large Pb-Zn deposit. In recent years, the geological characteristics of the deposit have been preliminarily studied, and the geochemical characteristics of the deposit have been studied. The study on the nature and source of ore-forming fluid, the source of ore-forming material and metallogenic regularity is weak, and the origin of ore deposit is controversial. In this paper, the geological characteristics, ore-hosting rock geochemistry, ore-forming fluid geochemistry, isotopic geochemistry of the Xiyi lead-zinc deposit are systematically studied, and the genetic types of the deposits are determined. A metallogenic model is put forward, and a comparative study is made with typical regional lead-zinc deposits. The ore-controlling factors of regional deposits are summarized, and the regional prospecting indicators are pointed out. The deposits are divided into three sections: Dongjiazhai, Zhaozhai and Lutu. The orebodies occur in the limestone of Xiangyangsi formation, Heyuanzhai formation and Xiangshan formation of Lower Carboniferous in Devonian system, controlled by the structure of NNE, and are stratiform, vein-like and lenticular. The main metallic minerals in the ore are galena and sphalerite, containing a small amount of pyrite. Occasionally, there are bauxite, chalcopyrite and arsenopyrite. The non-metallic minerals are mainly calcite and contain a small amount of barite. The metallogenic process is divided into three hydrothermal metallogenic stages: I sphalerite galena calcite II galena arsenopyrite + sphalerite and III calcite pyrite 卤barite 卤quartz. Isotopic studies show that. The ore-forming fluid is a H2O-NaCl system with a low temperature of 100 ~ 100 鈩，

本文编号：1645585