【作者】 刘陈明；

【导师】 燕永锋； 秦德先；

【作者基本信息】 昆明理工大学 ， 地球探测与信息技术， 2011， 硕士

【摘要】 本论文“广西大厂锡矿矿床地质与成因规律研究”是以本次中基火山岩的发现为基础,结合校企项目“大厂锡矿泥盆纪地层控矿规律与成矿预测研究”,以目前最新成矿理论—热水沉积成矿作用理论为指导展开的。广西大厂锡-多金属矿位于江南古陆西南缘的丹池褶断带北段,是中外著名的超大型锡多金属矿床,是我国重要的锡生产和出口基地。但随着多年矿山开采,矿产资源出现危机,加强找矿研究迫在眉睫。近几年笔者在大厂锡矿科研中,继在“东岩墙”发现了次玄武岩后(李晓等,2009),又在铜坑矿区和黑水沟中泥盆统层状锌铜矿体及其含矿岩系中发现了中基性火山岩(刘陈明等,2011),这些新的发现对矿床成因规律及找矿研究具有重要的意义,以期对大厂深边部找矿提供依据。就矿床成因而论,本文中叙述的那些地质关系和实际资料没有任何一种具有单独决定性的意义,但是从总体上来看,它们则强有力地表明,大厂矿田的层状矿体是同生热水沉积环境下形成的。然而这些事实不适用于那些显著不整合的穿层大脉以及其它接触变质的岩石和矿石。正如被前人研究所证实的,这些矿石是后生的,形成于白垩纪花岗岩侵入作用期间并与之有关。同块状硫化物矿床一样,如果不加区分地把各种地质现象都笼统考虑时,大厂矿床既不是同生的,也不是后生的,因为它兼有同生和后生的特征,而应是复生；大厂矿床既不是热水沉积成因的,也不是岩浆热液形成的,它既有热水沉积成矿作用的特点(层状矿体),又具有岩浆热液的特征(穿层大脉),所以说应是在多种地质作用过程中形成的。这些地质事件开始于前寒武纪的基性火山活动奠定物质基础,发展于海西期泥盆纪火山-热水沉积作用,结束于与燕山期花岗岩侵入有关的热液改造。通过本文的研究得出以下认识：(1)提出大厂矿区中泥盆统存在火山岩,论证火山岩为玄武-安山岩类岩石,属钙碱性-碱性系列,形成于大陆裂谷型环境。火山岩同上下围岩呈整合接触关系,具有纹层条带等典型的沉积构造特征,火山岩产出层位的上下围岩中含有大量竹节石等海相化石,与硅质岩和碳酸盐相间成层,火山岩应为海底火山活动产物。(2)探讨了硅质岩的成因,认为矿床硅质岩建造系海底热液循环系统中喷出海底的热水溶液以化学沉积方式形成的,生物可能参与了部分硅质岩的形成,但不是主要因素,另外,在某些热水沉积作用减弱时期,可能有少量陆源碎屑物质的加入,形成了硅质岩建造中少量绢云母泥质条带纹层条带。其中形成硅质岩的硅质来源,一部分主要应是海底热卤水循环系统,一部分应为海底中基性火山岩海解或脱玻的产物。(3)重新阐述矿床成矿作用过程和建立成矿作用模式,提出“四楼一梯”矿床结构模型和矿床三个成矿系列。论述了四堡-雪峰期、海西期和燕山期三个时期火山活动同成矿之间的成因关系,提出海西期火山活动不仅为盆地内热水沉积成矿作用提供热卤水循环的热能,还为成矿提供成矿物质来源。(4)提出大厂锡矿应为海相火山-热水沉积-后期叠加改造成因。矿床应为多种地质作用、多阶段下在特定地质环境中的产物,也是上地壳演化的结果。更多还原

【Abstract】 The thesis "The research of geology and origin law of tin ore in the Dachang Guangxi" is based on this discovery of neutral and basic volcanic rocks and combined with the school-enterprise project "Dachang tin ore-controlling law of the Devonian strata and mineralization prediction ", using the latest theory-the theory of hydrothermal sedimentary mineralization as the guide to start.The tin-polymetallic ore in Dachang located in the north end of Danchi fold belt of the southwestern edge of the Jiangnan archicontinent, is a remarkable large tin polymetallic deposits in the world, is China’s important production and export base of tin. But with the many years of mining, mineral resources crisis arises, is the time that strengthen the research of prospecting. In the research of recent years of Dachang tin ore, after finding the sub-basalt in the "East Rock wall" (Li Xiao etc., 2009), but also found the neutral and basic volcanic rocks in the stratiform copper-zinc ore body and ore-hosted strata of the Tongken and Heishuigou mines in the Middle Devonian (Liu Chenming, etc.,2011), these new findings have impotant meaning to the origin of ore and research of prospecting and deep and surrounding exploration.On the origin of ore is concerned, those described in this article geological relations and practical information does not have any kind of decisive significance single-handed, but in general terms, they forcefully indicate that the layered ore body of Dachang ore field is formed in the contemporaneous thermal water depositional surroundings. However, these facts do not apply to those observably unconformity contact through strata veins and other contact metamorphic rocks and minerals. As confirmed by previous research, these ores are epigenetic, formed during the Cretaceous granite intrusion and relate with it. As with the massive sulfide deposit, if without distinction of thinking about all the various geological phenomena, the Dachang deposit, neither with is syngenetic, nor is epigenetic, because it both has syngenetic and epigenetic characteristics, but should be a recombination; the origin of ore in the Dachang is neither thermal water depositional nor the formation of magmatic hydrothermal fluids, it has both the characteristics of hydrothermal sedimentary mineralization (stratiform ore body), but also has the characteristics of magmatic hydrothermal (though layer veins), so that should be the formation with a variety of geological processes. These geological events began in the Precambrian mafic volcanic activity laid the material foundation for the development of the Hercynian Devonian volcano-thermal water sedimentation, end up with the hydrothermal alteration which relates with the granite at Yanshan period.Through the study of the thesis reached the following understanding:(1) Think that there is volcanic rocks in the Dachang mining area of middle Devonian, the volcanic rocks belong to basaltic-andesite rocks and calc-alkaline-alkaline series, formed in a continental rift environment. The Volcanic rocks are conformable contact with the surrounding upper and lower rocks, with a lot of classic sedimentary structure characteristics of laminar and stripe, the output position of the volcanic rocks contains a lot marine fossils of tentaculitoid, these evidences indicate that the eruptions environment of the volcanic rocks is sea facies.(2) To discuss the origin of the silicalite, think that the siliceous rocks built of the deposit is formed form the hydrothermal solution with chemical deposition method, which eruption from the benthoal hydrothermal solution circulation system, organisms may be involved in the formation of some siliceous rocks, but not the main factors, In addition, in some time that the thermal water deposition decrease, there may be a small amount of detrital material join to form a small amount of sericite clay shale and lamina stripe of the siliceous rocks construction. The siliceous sources of the silicalite should be part of the main benthoal hot brine circulation system and part of the the neutral and basic volcanic rocks dissolving in the sea or devitrification.(3) To re-expound the process of mineralization and rebuild mineralization mode, put forward "the fourth floor of a ladder" of deposit structure model and three metallogenic series of the deposit. Discuss the the origin relationship between the volcanic activity of the Sibao-Xuefeng period, Hercynian and Yanshan period with the mineralization, think the volcanic activity of the Hercynian, not only provides heat energy to drive the hot brine cycle for the thermal water sedimentary mineralization, but also provides material source for the mineralization.(4) Put forward that the origin of the tin ore in the Dachang should be:sea facies volcano-thermal water deposition-overlying and reworking later. Deposit should be formed in the various geological processes and the multi-stage at the specific geological environment, but also is the result of the upper crust evolution.更多还原