滇西北白洋厂SSC型Cu-Ag矿床重晶石化特征及矿床成因
发布时间：2018-10-07 21:04
【摘要】：滇西北云龙白洋厂Cu-Ag矿床位于兰坪中-新生代盆地中南段。前人少量研究工作表明,区内Cu-Ag矿床属渗滤热卤水后生层控矿床或沉积-改造矿床。但本次调查发现,矿区内地层、构造等地质条件存在误解,且区内独具特点的Cu-Ag矿床成矿作用及成因机制尚未被揭示。为此,本文在对白洋厂矿区进行系统的地层、构造、矿化、蚀变填图的基础上,查明了Cu-Ag矿床(体)的基本地质特征,约束了其成矿时代；借助构造-岩相蚀变填图、岩矿相学及同位素示踪分析,重点查明了重晶石化的发育特征及时空分布规律,建立矿床的矿化-蚀变结构模型,分析了矿床成因。论文主要取得以下成果和认识：(1)矿区主要表现为以近南北向紧闭背斜、开阔向斜及与背斜伴生的正断层组合为发育特征的同沉积坳陷带,并发育构造垮塌体及含石膏砂泥底劈体；主要出露上白垩统南新组、虎头寺组及古-始新统云龙组砂泥岩均发育多层次的发育软沉积构造岩层；近南北向的F1断层为主要的导流控矿同沉积断层。(2)主要Cu-Ag矿体呈浸染状、细(网)脉状赋存于虎头寺组浅色岩屑长石石英砂岩及破碎角砾岩带中的浅色砂岩角砾中,伴生强烈的重晶石化及弱的方解石化与石膏化。地层岩性、同沉积断层、褶皱变形、构造垮塌体与含石膏砂泥底劈体的有机组合,控制了区内Cu-Ag矿床成矿流体的迁移及沉淀成矿。成矿作用过程可划分为成岩成矿期、热液成矿期和表生富集期。(3)从矿体中心往边部,重晶石化的产出形式依次为斑点状—细脉状—粗脉状,并明确了重晶石化与伴生金属硫化物矿化、方解石化的关系。(4)矿床的硫源具多来源性,并显示复杂的同位素分馏过程；铅源具有明显的壳源特点；锶来源于沉积岩围岩地层；成矿流体具有多来源性和混合流体特征。(5)本矿床属于沉积坳陷带背景下受同沉积变形构造控制的SSC型矿床,形成于虎头寺期晚期—云龙期早期(K2～E1-2)区域性拉张盆地向走滑拉分盆地转化阶段,是深部富集H2S排泄流体与当时湖水或盆地卤水迁移混合的产物。(6)提出白洋厂矿区南部是有利的找矿靶区。其中,上白垩统浅色砂岩中的斑点、细脉状重晶石及伴生的方解石、石膏等组合,是重要的找矿指示性标志。
[Abstract]:The Yunlong Baiyang Chang Cu-Ag deposit in northwest Yunnan is located in the middle and south section of Lanping Mesozoic-Cenozoic basin. A few previous studies have shown that the Cu-Ag deposits in the area belong to percolation heat brine epigenetic stratabound deposits or deposition-modified deposits. However, it is found that there are misunderstandings in geological conditions such as strata and structures in the interior of the mining area, and the metallogeny and genetic mechanism of the Cu-Ag deposit with unique characteristics in the area have not been revealed. Therefore, based on the systematic mapping of strata, structures, mineralization and alteration in Baiyangchang mining area, the basic geological characteristics of the Cu-Ag deposit (body) have been found out and its metallogenic epoch has been restricted by the help of tectonic-lithofacies alteration mapping. Based on the petrographic and isotopic tracer analysis, the developmental characteristics and space-time distribution of barite are found out, the mineralization-alteration structure model of the deposit is established, and the genesis of the deposit is analyzed. The main achievements of this paper are as follows: (1) the main features of the mining area are synsedimentary depression, which is characterized by the closed anticline, the open syncline and the normal fault association associated with the anticline. And developed structural collapse and gypsum bearing sand and mud bottom split, mainly exposed the Upper Cretaceous Nanxin formation, Hutousi formation and Paleo-Eocene Yunlong formation sand and mudstone all developed multiple layers of soft sedimentary structural strata; The F _ 1 fault near the north-south direction is the main flow-controlling ore-controlling synsedimentary fault. (2) the main Cu-Ag orebody is dyed, and the fine (net) vein occurs in the shallow-colored lithic feldspar quartz sandstone of the Hutousi formation and in the shallow-colored sandstone breccia in the broken breccia belt. Accompanied by strong barite and weak calcite and gypsum. The organic combination of stratigraphic lithology, synsedimentary faults, fold deformation, structural collapse and gypsum bearing sand and mud bottom cleavage controls the migration of ore-forming fluids and the precipitation of ore-forming fluids in Cu-Ag deposits in the region. The process of mineralization can be divided into diagenetic metallogenic stage, hydrothermal metallogenic stage and supergenetic enrichment stage. (3) from the center to the edge of the orebody, barite occurs in the order of dotted, vein-like and coarse-vein. The relationship between barite mineralization and associated metallic sulphide mineralization and calcite is also clarified. (4) the sulfur source of the deposit has multiple sources and shows complex isotopic fractionation process, lead source has obvious characteristics of crust source, strontium comes from sedimentary rock surrounding rock strata, and strontium comes from sedimentary rock and surrounding rock strata. The ore-forming fluid has the characteristics of multi-source and mixed fluid. (5) the deposit belongs to SSC type deposit controlled by synsedimentary deformation structure in the background of sedimentary depression. It was formed in the transition stage from the regional extensional basin to the strike-slip extensional basin in the late Hutousi period and the early Yunlong period (K2~E1-2). It is the product of the migration and mixing of deep enriched H 2S discharge fluid with lake water or basin brine at that time. (6) it is suggested that the southern part of Baiyangchang mining area is a favorable prospecting target area. The combination of spots, veinaceous barites and associated calcite and gypsum in the light colored sandstone of upper Cretaceous is an important indicator for prospecting.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.41;P618.52
[Abstract]:The Yunlong Baiyang Chang Cu-Ag deposit in northwest Yunnan is located in the middle and south section of Lanping Mesozoic-Cenozoic basin. A few previous studies have shown that the Cu-Ag deposits in the area belong to percolation heat brine epigenetic stratabound deposits or deposition-modified deposits. However, it is found that there are misunderstandings in geological conditions such as strata and structures in the interior of the mining area, and the metallogeny and genetic mechanism of the Cu-Ag deposit with unique characteristics in the area have not been revealed. Therefore, based on the systematic mapping of strata, structures, mineralization and alteration in Baiyangchang mining area, the basic geological characteristics of the Cu-Ag deposit (body) have been found out and its metallogenic epoch has been restricted by the help of tectonic-lithofacies alteration mapping. Based on the petrographic and isotopic tracer analysis, the developmental characteristics and space-time distribution of barite are found out, the mineralization-alteration structure model of the deposit is established, and the genesis of the deposit is analyzed. The main achievements of this paper are as follows: (1) the main features of the mining area are synsedimentary depression, which is characterized by the closed anticline, the open syncline and the normal fault association associated with the anticline. And developed structural collapse and gypsum bearing sand and mud bottom split, mainly exposed the Upper Cretaceous Nanxin formation, Hutousi formation and Paleo-Eocene Yunlong formation sand and mudstone all developed multiple layers of soft sedimentary structural strata; The F _ 1 fault near the north-south direction is the main flow-controlling ore-controlling synsedimentary fault. (2) the main Cu-Ag orebody is dyed, and the fine (net) vein occurs in the shallow-colored lithic feldspar quartz sandstone of the Hutousi formation and in the shallow-colored sandstone breccia in the broken breccia belt. Accompanied by strong barite and weak calcite and gypsum. The organic combination of stratigraphic lithology, synsedimentary faults, fold deformation, structural collapse and gypsum bearing sand and mud bottom cleavage controls the migration of ore-forming fluids and the precipitation of ore-forming fluids in Cu-Ag deposits in the region. The process of mineralization can be divided into diagenetic metallogenic stage, hydrothermal metallogenic stage and supergenetic enrichment stage. (3) from the center to the edge of the orebody, barite occurs in the order of dotted, vein-like and coarse-vein. The relationship between barite mineralization and associated metallic sulphide mineralization and calcite is also clarified. (4) the sulfur source of the deposit has multiple sources and shows complex isotopic fractionation process, lead source has obvious characteristics of crust source, strontium comes from sedimentary rock surrounding rock strata, and strontium comes from sedimentary rock and surrounding rock strata. The ore-forming fluid has the characteristics of multi-source and mixed fluid. (5) the deposit belongs to SSC type deposit controlled by synsedimentary deformation structure in the background of sedimentary depression. It was formed in the transition stage from the regional extensional basin to the strike-slip extensional basin in the late Hutousi period and the early Yunlong period (K2~E1-2). It is the product of the migration and mixing of deep enriched H 2S discharge fluid with lake water or basin brine at that time. (6) it is suggested that the southern part of Baiyangchang mining area is a favorable prospecting target area. The combination of spots, veinaceous barites and associated calcite and gypsum in the light colored sandstone of upper Cretaceous is an important indicator for prospecting.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.41;P618.52
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