【作者】 杨红英；

【导师】 钟康惠；

【作者基本信息】 成都理工大学 ， 构造地质学， 2009， 硕士

【摘要】 四川省宁南县银厂沟-骑骡沟铅锌矿床,区域上位于扬子地块西南缘康滇地轴东侧的川滇黔铅锌多金属成矿带上,为川滇黔重要构造金属成矿带,受到前人的高度重视。本文在充分收集前人的资料和研究成果上,从构造地质基础入手,分别从区域构造演化、构造变形特征、矿床基本特征、构造控矿特征、矿体年代学特征等几个方面,分析区域构造及矿田构造对矿带及矿体的控制作用,得出以下结论:1.在长期的地质演化历史中,宁南地区经历了元古代EW向拗拉槽和震旦纪-早古生代SN向陆架裂陷、晚二叠世-中新生代SN向大陆裂谷等发展阶段。显生宙的SN向裂谷(陷)叠加在EW向拗拉槽裂陷之上,具有横跨式叠加裂谷系的特征。宁南地区就处在EW向和SN向裂谷构造叠加的部位。2.各个构造演化阶段均与成矿关系密切:元古代会理-东川EW向坳拉槽形成川滇黔地区的基底构造,控制川滇黔地区的铅锌矿带的分布;震旦纪-早古生代SN向陆架裂陷形成了该区有利成矿的容矿屏蔽岩性组合;晚二叠世-中新生代SN向大陆裂谷阶段深部地幔物质伴随岩石圈伸展裂陷而上涌至表壳;新生代岩石圈收缩挤压,使裂谷封闭褶皱,集于表壳的矿液,在适宜的构造(如背斜皱褶、转折端、张性断裂等)和具有屏蔽-容矿岩石组合的地层组成的储闭系统中成矿。3.研究表明银厂沟-骑骡沟铅锌矿区基本地质构造格架为:近南北向的骑骡沟背斜,次级的横向和纵向小幅褶皱;北北西、南北、北北东向纵向断裂,东西向的横向断裂以及早晚两期顺层剪切构造。4.铅锌矿体产于白云岩与硅化岩石中;受纵向断裂控制;在走向和倾向上均具尖灭再现与侧列再现特点;成矿年代学研究表明有三期成矿作用,主要形成于晚燕山期以来的脆性变形期;矿床属于热液矿床。5.结合成矿期次分析矿区构造变形序列为:骑骡沟背斜形成伴随早期顺层剪切→NNW向断裂形成并逆冲、纵向小幅褶皱形成,SN向断裂形成→NNW向断裂左行正滑、SN断裂左行逆冲,横向小幅褶皱形成→NNW向断裂右行逆冲、近SN向小断裂右行正滑→NE向、NW向断裂及EW向断裂形成,后期顺层剪切。6.总结了银厂沟-骑骡沟铅锌矿床的构造控矿特征:小江断裂为导矿构造,次级南北向张性断裂为配矿构造,北北西向、近南北向断裂及早期顺层剪切破碎带、横向和纵向小背斜为容矿构造,广泛发育的上震旦统灯影组白云岩为容矿地层。更多还原

【Abstract】 Yinchanggou-qiluogou Pb-Zn ore deposits in Ningnan County, Sichuan Province, which are located in Sichuan-Yunnan-Guizhou Pb-Zn polymetallic metallogenic belt in east of Kangdian earth axis in southwest of Yangtze block, are an important structurally Sichuan-Yunnan-Guizhou metallogenic belt, and thus have been capturing numerous geologists’extensive attention.Based on sufficient former researches and data, starting with foundational structure geology, analyses about how structure is controlling Pb-Zn deposits is involved in this paper from regional tectonic evolution, tectonic deformation features, characteristics of deposits, structural ore-control characteristics, orebody chronology and other aspects. Initial discussion has gain following conclusion:1.During long geological evolutionary history, Ningnan area experienced following seedtimes: EW-trending aulacogen in Proterozoic, SN-trending continental shelf rift in Sinian-early Paleozonic, SN-trending continental rift in late Permian-meso Cenozoic. Rift of different tectonic cycles and different tectonic stages develops in the same area, leading to formation of supraposition rift. SN-trending rift of Phanerozoic overlays on EW-trending aulacogen, pocessing cross-straddletype supraposition rift. Ningnan area is just located in crunode between EW-trending and SN-trending rift.2.All tectonic evolution stages have a close relationship with mineralization. Huili-Dongchuan EW-trending aulacogen of Proterozoic formed basement structure of Sichuan-Yunnan-Guizhou, which controlled the distribution of Pb-Zn ore band; SN-trending continental shelf rift of Sinian-early Paleozonic formed ore-containing shielding lithologic association good for mineralization; and during SN-trending continental rift of late Permian-meso Cenozoic and other seedtimes, deep mantle substances upwell to supracrustal with extensional rift of lithosphere; shrink and extrusion of lithosphere in Cenozoic leaded to closed folds, ore solution gathering in supracrustal formed mineralization with adequate structure such as tensional fracture, turn end, anticline ruga and so on, and reservoir-close system consisting of stratum having shielding-ore containing lithologic association.3.Our reseach shows that the primary geologic tectonic pattern in Yinchanggou-qiluogou Pb-Zn mining area presented as following: Qiluogou anticline trending near NS direction; secondary transverse and longitudinal small amplitude folds; NNW-trending, NS-trending and NNE-trending longitudinal rupture, transmeridional transverse rupture and early and late phases consequent landslide.4.Pb-Zn ore body primarily occurs in dolomite or silicified rocks; ore body is controlled NS and NNW rupture, characterizing thin out reconstruction and in both tendency and trend; research of mineralization chronology suggests that three periods’mineralization is formed primarily during brittle deformation stage since late Yanshanian; mineral deposits belongs to hydrothermal deposits.5. According to analysis , the structural deformation sequence is as following: Qiluogou anticline formed with early layer shearing→NNW- trending to fracture and thrust and longitudinal small amplitude folds,SN-trending formation→NNW- trending left lateral normal slip、SN- trending left lateral line thrust, transverse small amplitude folds→NNW- trending right lateral normal slip、NS trending small fracture left lateral normal slip→NW- trending、NE- trending and EW- trending formed, late fracture in the shear.6. Structural ore-control characteristics of Yinchanggou-qiluogou Pb-Zn deposits are summarized in the paper: Xiaojiang rupture is the ore conducting structure; secondary NS-trending and NNW-trending tensional fracture is ore blending structure; NNW-trending and near NS-trending rupture, early bedding shear fracture zone and transverse and longitudinal small anticline constitute host structure; extensively developed Dengying dolomite, Upper Sinian is the host strata.更多还原