黔西北地区铅锌矿矿床成矿规律与找矿研究

【作者】 董家龙；

【导师】 李俊； 金中国；

【作者基本信息】 昆明理工大学 ， 地质工程， 2008， 硕士

【摘要】 黔西北铅锌成矿区位于扬子准地台西南缘,小江、师宗—弥勒、垭都—紫云三条深大断裂所围限的区域内,是川-滇-黔铅锌成矿域的重要组成部分,也是贵州省重要的铅锌产地之一。区内铅锌矿床(点),物、化探异常成群成带展布,成矿地质条件优越,找矿前景好,具备寻找中、大型矿床的潜力。黔西北铅锌成矿区区域构造展布、铅锌矿化分布具明显的带状分布特征。本论文根据陈毓川院士、裴荣富院士等关于中国成矿区带的划分方案,结合黔西北铅锌成矿区构造和矿化特点,划分出4个构造带,3个成矿亚带,较详细的阐述了区域构造演化特征,各构造带、成矿亚带的地质特征及成矿特点,物化探异常与铅锌成矿的关系。铅锌成矿控矿因素研究表明,本区铅锌成矿受地层(S1-2hj-P2m)、岩性(碳酸盐岩)、火成岩(辉绿岩旁侧、玄武岩层位之下)、岩相(上泥质(页)岩相,下碳酸盐岩相叠置组合)、沉积环境(水下脊状隆起内侧,封闭—半封闭的还原泻湖沉积环境)控制。岩性控矿优于层位,区域主要含矿层位从西到东,从南到北空间分布上逐渐抬升,时间演化上逐渐变新,川西南以震旦系为主→滇东北以以震旦系,中、下寒武统为主→黔西北以石炭系为主。矿床组合由Cu-Pb-Zn→Pb-Zn-V→Pb-Zn(Ag),从而显示黔西北地区剥蚀程度低,含矿层位保留完好,深部找矿潜力大。断裂构造是最主要的控矿因素,构造分级控矿特点明显,即断陷盆地边缘控制矿带的展布→紧密褶皱及其核部发育的纵断层控制矿田的展布→矿内主干断层与次级断层交汇部位、背斜倾斜端控制矿床和矿体的产出。区域性大断裂+次级断层+层间挤压破碎带(层间滑动面、牵引虚脱空间)是良好的构造控矿配套系统和导、聚、储矿系统。区内Pb、S、C、O同位素特征、稀土元素配分特征,典型矿床矿石与围岩Pb/Zn比值特征,区域地球化学背景场特征显示,成矿物质具多来源,成矿作用具多阶段性。成矿元素Pb、Zn、Ag主要来源于下伏老地层,与下寒武统碎屑岩,前震旦系基底火山碎屑岩有关,也与峨眉山玄武岩的喷发及同期异相辉绿岩的侵位有成生联系。成矿流体中S、0来自海相硫酸盐,C来源于海相碳酸盐,成矿流体水主要来源于深部地层变质水,有少量大气降水混合。矿石包裹体特征显示,成矿流体性质属低温,中高盐度,强还原条件,弱减—弱酸性,高矿化度的Ca2+-Na+-Cl- (SO42-)型热液。矿床成因类型与世界上密西西比河谷型(MVT)铅锌矿床相比具相似性,但浅表陡脉状矿产出特征明显,属不典型的MVT铅锌矿床。结合区域构造演化特征,成矿地质特点,综合控矿因素与成矿规律,建立了本区成矿物质多来源,成矿多阶段的MVT成矿模式和以断裂构造为主要控制因素的综合找矿模式。各成矿区带典型矿床(区)找矿潜力分析及成矿预测研究认为,黔西北地区深部找矿潜力巨大,具备寻找中大型矿床的条件。重要找矿靶区为赫章猫猫厂—榨子厂矿区深部,垭都—蟒硐断裂带的垭都、筲箕湾矿区深部及外围；水城青山矿区深部及为外围,杉树林矿区深部；威宁银厂坡矿区深部。浅表以寻找陡脉状断裂型为主,深部第二赋矿空间(大于500M)以寻找似层状层间断裂型为主,指明了该区今后的找矿方向和主攻类型。更多还原

【Abstract】 The lead and zinc metallogenic zone in Chuan-Dian-Qian.district lies at the southwest edge of Yangzi platform and in the zone which is surrounded by three deep fracture zones named by Xiaojiang, Shi zhong-MiLe, YaDou-ZiYun. The metallogenic zone is one of sixteen important metallogenic provinces during "10.5 Year Plan "and" 11.5 Year Plan "in our country. The metallogenic zone of lead and zinc ore in the northwest of Qian lies at the east of the metallogenic zone of lead and zinc ore in Chuan-Dian-Qian district. It is one of the important lead and zinc mines in Guizhou province. This place has the potential of seeking middle-scale or large-scale lead and zinc deposit, because physics and chemistry prospection abnormity appears the group-shaped and belt-shaped distribution and the metallogenic geological condition is superior.Regional structure spreading in the lead and zinc metallogenic zone in the northwest of Qian and lead-zinc mineralization in this place takes on obvious belt-shaped distributing character. The author divides four structure belts and three metallogenic sub-belts based on the structure and mineralization feature of the metallogenic zone. This dissertation firstly sets forth in the detail the evolvement character of regional structure, the geologic character and metallogenic character of every structure belt and metallogenic sub-belt, the relation between physics and chemistry prospection abnormity and lead and zinc metallogeny.The research on the metallogenic factor and controlling factors for lead-zinc deposits shows that the metallogenic factors of lead and zinc in this place include stratum(Sl-2hj-P2m), lithology(carbonate rock), structure (NW overthrust fault mainly+NE cross fracture+fracture belt and anticline plunging end), eruptive (beside diabase, under basalt stratum), lithofacies (overlap up argillaceous and under carbonate lithofacies), sediment environment (inboard submarine carinate uplift.closed or half-closed reducing lagoon deposit entironment) etc. Fracture is the most important controlling metallogeny factor and control factors for ore deposit by lithology precede over horizon. The main ore-containning horizon in this place gradually runs up from the west to the east, from south to north in the spatial distribution and becomes new step by step in the time evolution. These phenomena shows that denudation degree is low in the northwest of Qian, horizon ore-containning keep in good condition and the depth portion prospecting has the very good prospect.Graduation controlling ore by the structure is obvious. Fault-basin edge controls ore belt extent→compacted folds and longitudinal fault growing from the core of compacted fold controls mineral deposit extent→the intersecting position of trunk fault and sub-fault and arch lean end in mineral deposit control mineral deposit and orebody attitude. REgional big fracture +sub-fracture+extrusion crush belt in stratum are good controlling ore system by structure and collecting, storage ore system. This dissertation firstly research all-sided ore-controlling mechanism by structures.The characteristics of Pb、S、C、O isotopes, REE and regional geochemistry background show the metallogenic substance has many sources and metallogenic action has many stages. Metallogenic element Pb、Zn、Ag mainly came from underlying old stratum. Their cause of formation have been related with sub cambrian system clasolite, presinian basement pyroclastic rock and E Mei Mountain basalt. S、O in metallogenic liquid came from sea phase sulfate, C came from sea phase carbonate, water mainly came from deep stratum metamorphic water and partly from precipitation.The character of ore inclusion reveals that the metallogenic fluid is a Ca-Na-Cl(SO4) mineralization liquid which has low temperature, middle-high salinity, reducing condition, weakly-alkali—weakly-acidic, and high mineralised quality.Study shows that the genetic type of the ore deposits is similar to Mississppi valley type (MVT) lead and zinc deposits, but the vein-shaped character in shallow site is obvious, which reveals the ore deposits is not a typed MVT one. Combining the character of the regional structural evolvement and the metallogenic geological quality, the author sets up the MVT model of metallogeny of the local district and the synthetical model of seeking mine, whose mainly controlled factor is fracture structure.Synthesizing the minerals potential, metallogenic prognosis and recent years results for all typical mineral deposites (fields) in the metallogenic provinces the author believes that the North-West of Qian in deep parts have huge potential to mineral deposits, and have middle-large deposits’conditions. The important mineral-finding target zones are Hezhangmaomaochang-Zhaizichang ore field deep parts; Yadu-Mangdong fracture zone’s Yadu, Xiaojiwan ore field deep parts and periphery; Shuicheng-Qing mountain ore field deep parts and periphery, Shanshulin ore field deep parts; Weining-Yinchangpo ore field deep parts. Superficial places mainly seek to steep-nervation fracture type, deep parts (exceed 500meters) mainly find out Stratoid-Interstratification fracture zones, which all indicate this zone seek to mineral’s directions and main research types in future.更多还原