峨眉地幔热柱活动与贞丰水银洞金矿床形成关系研究硕士研究生论文.doc

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1、分 类 号:论文编号:密级:贵大学硕士研究生学位论文峨眉地幔热柱活动与贞丰水银洞金矿床形成关系研究学科专业: 矿物学岩石学矿床学 研究方向: 卡林型金矿成因研究60 / 73目录摘要ISummaryIV第一章:绪论11.1本项研究的的选题依据与意义11.1.1选题依据11.1.2研究意义21.2本项研究容和方案31.2.1本论文的主要研究容31.2.2本论文的研究方案31.2.3本次研究工作完成工作量31.3研究历史与现状4第二章:峨眉地幔热柱活动特征72.1地幔柱理论的起源与演化72.1.1地幔柱理论与其起源72.1.2幔柱构造的三层次构造92.2峨眉地幔热柱的活动特征102.2.1峨眉地幔

2、热柱活动特征102.2.2峨眉地幔热柱活动的地质效应11第三章:峨眉地幔热柱活动形成区域地质背景133.1 构造位置133.2 区域地层133.2.1区域地层133.2.2区域含金层序153.3区域构造163.3.1区域表层构造163.3.2区域深大断裂183.4区域岩浆岩203.4.1区域岩浆岩简介203.4.2峨眉山玄武岩特征213.5区域地热异常223.6峨眉地幔热柱隆起与古地理变化24第四章:水银洞金矿床地质特征264.1赋矿地层与岩石264.2 矿体特征274.3 矿石特征304.3.1矿石304.3.2载金矿物与金的赋存状态304.3.3围岩蚀变特征34第五章:峨眉地幔热柱活动形成

3、水银洞金矿成因初探355.1晚古生代峨眉地幔热柱活动的成矿贡献355.1.1成矿物质来源355.1.2含矿建造形成与金的初步富集405.1.3 成矿流体形成425.2中生代峨眉地幔热柱活动的成矿贡献455.2.1幔柱构造活动对矿区成矿构造影响455.2.2水银洞金矿成因机理46结论50致52参考文献53附录58贵 大 学2009届硕士研究生学位论文（详细摘要）峨眉地幔热柱活动与贞丰水银洞金矿床形成关系研究学科专业：矿物学岩石学矿床学研究方向：卡林型金矿成因研究导 师： 聂 爱 国 教授研 究 生： 梅 世 全中国贵2009年6月峨眉地幔热柱活动与贞丰水银洞金矿床形成关系研究摘要中国卡林型金矿主

4、要产于“滇黔桂”、“川甘陕”与“滇西”地区，其中以“滇黔桂”为主体。“滇黔桂”、“川甘陕”与“滇西”地区均位于峨眉地幔热柱活动区。黔西南地区金矿是“滇黔桂”金三角的主体，其中以贞丰水银洞金矿最具代表性：该矿床金矿矿石品位高、矿体厚度与矿石品位变化系数小，是我国第一个类勘探类型金矿床。该矿床已达特大型规模，为亚洲最大的金矿床。选择水银洞金矿为研究对象，对于探索峨眉地幔热柱活动对该矿床的形成与对区域成矿的控制有重论意义和现实意义。全文共分五章，首先介绍地幔柱理论的起源与峨眉地幔热柱的活动特征，其次论述峨眉地幔热柱活动形成区域地质背景；再次，阐述水银洞金矿床地质特征；最后探讨峨眉地幔热柱活动形成水银

5、洞金矿床的成因机制。本论文取得以下认识和成果：（1）水银洞金矿床位于灰家堡金、汞、铊矿矿田带东段，是黔西南金矿矿集区发现较晚、规模较大、品位较高的隐伏岩金矿床；矿床赋存于上二叠统龙潭组煤系地层与其与下伏的茅口组石灰岩之上的炭硅质岩（俗称“大厂层”）中，矿床由若干矿体组成，多个矿层垂直空间上下重叠，受灰家堡背斜严格控制：金矿体在背斜核部向两翼300m围产出；单个矿体呈层状、似层状、透镜状、扁豆状，顺层产于地层中，矿体产状与围岩产状一致；该地层中岩石普遍含有百分之几到百分之几十的玄武质火山碎屑；矿体主要赋存于生物碎屑灰岩中，为金的主要载体；矿石矿物有黄铁矿、毒砂与硅酸盐矿物等，其中黄铁矿是金的主要

6、载体，含金量占各种矿石矿物含金量的89%以上。含金黄铁矿有四种类型：草莓状黄铁矿、细粒黄铁矿、粗粒黄铁矿与生物碎屑黄铁矿，其中以生物碎屑状黄铁矿含金最高；金矿物相分析与电子探针分析结果显示，金主要呈包裹金形式存在于热液期含砷黄铁矿中；（2）峨眉地幔热柱是中国典型的地幔热柱之一。其岩浆活动始于晚古生代泥盆纪，大规模发育于晚古生代二叠纪至整个中生代，可延续到新生代早期。其中，早期阶段（晚古生代）以基性岩浆大规模喷发活动为主，晚期阶段（中生代-新生代早期）以酸性与碱性岩浆大规模侵入为主，伴随少量的基性-超基性岩浆侵入活动；（3）峨眉地幔热柱活动形成含矿岩浆：地幔热柱边部温度比轴部低，深大断裂也不如轴

7、部发育，减压熔融效应不明显，形成部分熔融程度小的岩浆。金在岩浆演化中是不相容元素，它在熔体中的浓度随部分熔融程度的增大而减小。所以金在这种小部分熔融程度岩浆中易于富集；（4）海西-印支期峨眉地幔热柱活动产生多条深大断裂，这些深大断裂不仅是峨眉山玄武岩喷溢的通道，也是深部含矿热液与深渗与上升的通道。它沟通了地球深部与浅部之间的物质与能量交换。其中峨眉地幔热柱边部的深大断裂是富金岩浆运移的主要通道；（5）海西-印支期峨眉地幔热柱活动造成岩石圈穹状隆起，明显改变了中国西南地区沉积格局。在贵西部表现为掀斜式抬升，龙潭期在贞丰、兴仁与安龙一带沉积环境由开阔碳酸盐台地沉积环境变为局限的潮坪-泻湖至局限碳酸

8、盐台地沉积环境。峨眉山玄武岩通过喷发-沉积进入这一局限的沉积盆地，形成初步富金的含矿建造（矿源层）；峨眉地幔热柱的脉动式活动,造成峨眉山玄武岩多次喷发与海水频繁进退,在上二叠统龙潭组地层中形成含、隔水层岩石频繁交替多层矿源层。（6）海西-印支期至燕山期，峨眉地幔热柱长期活动形成区域热异常，大气降水、海水、地下水与岩浆水等深渗循环不断从峨眉山玄武岩、“大厂层”、含矿建造中萃取大量的Au等成矿物质形成金硅络合物、金硫络合物等形式迁移的成矿热液。(7)燕山期峨眉地幔热柱再次强烈活动,在形成灰家堡背斜过程中，产生大规模的断裂构造与层间滑脱构造，大量的含矿热液通过断裂构造沿着层间滑动面与层间破碎带向灰家

9、堡背斜核部迁移。当构造应力进一步加大，在灰家堡背斜核部产生成矿期逆冲断层与层间破碎带，成矿体系从封闭变成开放，应力突然得以释放，含矿热液的物理化学条件改变，导致热液体系快速远离平衡态，使络合物失稳，金伴随着大量隐晶-微晶二氧化硅-似碧岩和热液期黄铁矿与含砷、锑、汞等硫化物的沉淀而成矿形成水银洞金矿床。（8）初步建立了水银洞金矿床的峨眉地幔热柱成矿模式：峨眉地幔热柱在海西-印支期强烈活动，一方面改变了中国西南地区沉积格局，造成水银洞沉积环境由开阔碳酸盐台地沉积环境变为局限的潮坪-泻湖至局限碳酸盐台地沉积环境；另一方面，峨眉地幔热柱边部形成富金岩浆，并沿峨眉地幔热柱边部的同生深大断裂上升，通过喷发

10、-沉积作用方式进入潮坪-泻湖至局限碳酸盐台地沉积环境。在峨眉地幔热柱的脉动式活动作用下，造成多次峨眉山玄武岩喷发和海水频繁进退，在上二叠统龙潭组地层中形成具含、隔水层岩石频繁交替的复杂岩性组合的多层含矿建造(矿源层)；海西-印支期至燕山期，峨眉地幔热柱长期活动形成区域热异常，大气降水、海水、地下水与岩浆水等深渗循环不断从峨眉山玄武岩、“大厂层”与含矿建造中萃取大量的Au等成矿物质形成金硅络合物、金硫络合物等形式迁移的成矿热液；燕山期峨眉地幔热柱再次强烈活动,在形成灰家堡背斜过程中，产生大规模的断裂构造与层间滑脱构造，大量的含矿热液通过断裂构造沿着层间滑动面与层间破碎带向灰家堡背斜核部迁移。当构

11、造应力进一步加大，在灰家堡背斜核部产生成矿期纵向逆冲断层与层间破碎带，成矿体系从封闭变成开放，应力突然得以释放，含矿热液的物理化学条件改变，导致热液体系快速远离平衡态，使络合物失稳，金伴随着大量隐晶-微晶二氧化硅-似碧岩和热液期黄铁矿与含砷、锑、汞等硫化物的沉淀而成矿,形成水银洞金矿床关键词:峨眉地幔热柱 水银洞金矿床 矿源层 形成关系 成矿模式The study of the relationship between Emei mantle plume activity and Zhenfeng Shuiyindong gold depositsSummaryChinese carlin-t

12、ype gold deposits are mainly located inthe“YunnanGuizhou-Guangxi”，“Sichuan-Gansu-Shanxi” and the west of Yunnan region, which are located in the area of Emei mantle plume activity. The gold deposit in west of Guizhou is most prominent in “Yunnan-Guizhou-Guangxi”. .Shuiyingdonggold deposit is the rep

13、resentative among those gold deposits: the gold ore is high-grade,is few affected by geologic structure which after metallogenesis.It is the first I type exploration in china,and it is the super-large gold deposit.The deposit is hosted in the coal measures strata in the upper Permian Longtan Formati

14、on and the carbonaceous silicalite above the subjacent limestone of Permian Maokou Formation, which composed of a number of orebody, multiple ledge overlapped vertical space from top to bottom, the orebodies locate the high point of geological structure. The single orebody is stratiform, atoid struc

15、ture, lentoid, lenticular, existed in strata, its occurrence is consistent with the adjacent rock . Study Shuiyindong gold deposit which is helpful understand the genesis of mantle plume structure of the deposit. And rich the regional metallogenic theory that have practical significance.there also a

16、re significanc to rich the mantle plume theory.The full text is divided into five chapters.First, introduce the theory of mantle plume and the activity characteristics of the Emei mantle plume, followed by discuss that Emei mantle plume activity form regional geological background; again, introduce

17、the geological characteristics of Shuiyindong gold deposit; Finally dicuss the genesis of the Shuiyindong gold deposit under the activity of the Emei mantle plume. And get the following recognise and results:(1) Emei mantle plume is one of the typical mantle plume in China. The magmatic activity beg

18、an in the Devonian, Late Paleozoic. large-scale development in the Late Paleozoic Permian to the entire Mesozoic, may continue into the early Cenozoic. On the early stage (Late Paleozoic),The activity of the Emei mantle plume cause large scale eruption of Mafic magma.On the late stage (Mesozoic - ea

19、rly Cenozoic), The activity of the Emei mantle plume cause the large-scale invasion of the acidic and alkaline magma ,accompanied by a small number of basic - ultrabasic magma invasive activity.(2) The activity of the Emei mantle plume formed the gold-rich parent magma: the temperature of the mantle

20、 plume edge is lower than the cener of the mantle plume. deep fault is not developmented than the axis of the mantle plume, decompression melting is also developmented than the axis of th e mantle plume. small degrees of partial melting of the parent magma is formed in edge of the mantle plume. gold

21、 are incompatible elements in the magmatic evolution,so the concentration of the gold in the small degree of partial melting of is more richer;(3) Hercynian-Indosinian Emei mantle plume generated a number of faults, the deep fault is not only the eruption of Emeishan basalt channel, but also the cha

22、nnel of the deep hydrothermal ore-day and the water deeply Filtrated and raised channel. It communicate between the deep earth and the shallow with the material and the energy exchange. the deep fault of Emei mantle plume is the main channel of gold-rich magma migration;(4)Emei mantle plume activity

23、 caused the dome-like uplift ofthe lithospheric, significantly changed the deposition pattern of Chinas southwestern region. It is tilting-style uplift at the western Guizhou, parts of south-west of Guizhou (including Shuiyingdong) the carbonate platform depositional environment become limited tidal

24、 flat - lagoon depositional environment in parts of south-west of Guizhou (including Shuiyingdong). the Emeishan basalt come into the the limited basin by eruption- sediment, formed the initial source of the gold-rich layer; Emei mantle plume pulsating activity, caused many times of eruptions of Eme

25、ishan basalt, formed the formation of many source of ore layer. in the Upper Permian Longtan;(5) The rate of Geothermal warming and the radioactive heat can not explain the abnormal heat in southwest Guizhou. The long-term activity of the Emei mantle plume caused heat in southwest of Guizhou, provid

26、e heat source for the formation of gold deposits;(6)Shuiyindong gold deposit is strictly located by the HuiJiabao anticline, Gold body is located in 300 meters Range of the anticline core to the scope of the two wings, Many Orebodies overlap upperly and lowely. produced in the Permian Longtan Format

27、ion conformitily in different shap of Layered, like layered, lens, lentil-shaped. Ore formation is mainly the Permian Longtan central and lower Formation. The rock of the formation generally contain a few percent to tens percent of basaltic pyroclastic. The main ore body occurs in limestones of biol

28、ogical which is the Carriers of gold. Ore mineral are Pyrite, Arsenopyrite and Silicate minerals etc. Pyrite is the mainly Carriers of gold which pyrite contain more than 89% gold in a variety of gold-bearing ore minerals. There are four types of Gold-bearing pyrite: Strawberry-shaped pyrite, Fine-g

29、rained pyrite, Coarse-grained pyrite and Bio-clastic pyrite. Bio-clastic pyrite is the hignest gold-bearing type. The results of the Gold mineral phase analysis and Electron microprobe analysis Reveal that gold is mainly located in hydrothermal period Arsenic pyrite;(7)Yanshanian the activity of the

30、 Emei mantle plume modified the source of ore in the process of the formation of Huijiabao anticline, in the atmospheric precipitation, water and construction of magma under the action of water, actived, transfered the the mineral from the wings of the anticline to the core, concentration, and form

31、the floor control-type ore body and the fracture-type ore body: the upper part of the Longtan Formation, because of the fracture of the upper strata, communicated between the contact with the outside world, the ore-bearing fluid rapid acceed to fracture in the formation, formed relatively low grade

32、gold fracture-type ore body; for the hydrothermal gold-bearing strata in the lower part of Longtan Formation, because the balance of the ore-bearing hydrothermal system is not breaked heavly, gold quality sedimented in the limited range (anticline core) formed the higher grade stratabound-type ore b

33、ody;(8) The main genesis of Shuiyindong gold has the following three aspects: first, Emei mantle plume activity,in the edge o mantle plume forme the gold-rich magma; second, gold-rich magma erupted and spilled belong the deep fault in the edge of Emei mantle plume ,then sedimented in a relatively is

34、olated tidal flat - lagoon environment that is conducive to the preservation of gold; Third, because of the block of coal and clayr, the hydrothermal in the lower part in Longtan group formed the ore rich body in a relatively limited space (anticline core) through filling etc;(9) build the mantle pl

35、ume mineralization model of the Shuiyingdong gold deposit Preliminary: Emei mantle plume strongly activite in the Hercynian Indosinian:On the one hand, the activite changed the pattern of deposition in southwest of China, the depositional environment of Shuiyindong is changed from carbonate plat to

36、a limited tidal flat - lagoon sediment, On the other hand, formed the gold-rich magma in the Emei mantle plume edge.the gold-rich magma Raise along the deep fault in the edge of the Emei mantle plume, the gold-rich magma go into the Tidal flatlagoon by Eruptionsedimentation. under the Emei mantle pl

37、ume pulsely activity, Emeishan basalt erupted many times and Frequent advance and retreat of sea water, formed a limestone + seam (or clay rocks) Combination of complex lithology Multi-storey Source of ore. Yanshanian Emeishan mantle plume active strongly once again, in the process of form HuiJiabao

38、 Anticline, under the affect of the Abnormal heat , Tectonic stress and Ore-bearing fluid, Transformed the source bed, the gold migrate along the dimensions of to the core of the Huijiabao anticline.The Tectonic stress increase Gradually, formed Ore-forming stage fracture in the The upper part of th

39、e Longtan Formation. Because of the Ore-forming stage fracture can not connected the ore-bearing fluid in the the lower part of the source of ore. on the one hand, change conditions of the floor control-type ore fluid system,caused the sediment of the gold mineral in a limited space,formed the layer

40、-control-type body; . On the other hand, the Ore-forming stage fracture connected the the upper part of the ore fluids in the upper source of ore, , the ore-bearing fluids go fast into the ore-forming period of rapid fracture, formed the stratabound-type ore body in the upper strata.Key word:Emei ma

41、ntle plume Shuiyindong gold deposit gold ore source bed the relationship of formationMetallogenic model第一章:绪论1.1本项研究的的选题依据与意义1.1.1选题依据“滇黔桂”金三角是我国主要金矿矿集区，其中的黔西南地区是“滇黔桂”金三角的重要组成部分。黔西南地区已有超大型金矿床、大型金矿床多处，如水银洞金矿、烂泥沟金矿、紫木凼金矿、板其金矿、丫他金矿与戈塘金矿等。在这些金矿床中，水银洞金矿床尤其引人注目：矿体赋存于二叠系龙潭组地层中，矿体以层控型为主，矿体产状与地层产状一致，空间上多个矿体重

42、叠，单个矿体规模大。其中主要矿体规模大，组分均匀，厚度稳定，成矿期后破坏小；勘探类型简单,属勘探类型卡林型金矿床；矿床矿石品位高，平均达20g/t以上，最高达3位数(聂爱国,2006),储量大，累计提交黄金资源储量达XXX吨，已达超大型规模。这些显著区别于其它矿床的特征引起矿床学界的高度重视和广泛关注。水银洞金矿位于贵省西南部，贞丰县北西直距约18km，隶属于贞丰县小屯乡所辖（图1.1）。地理位置：东经1053000-1053338，北纬253100-253328。图1.1 研究区位置图众所周知，中国西南地区是我国重要矿集区之一，具有矿床产出集中，矿种类型多样，超大型，大型矿床大量产出等特点。

43、如钒钛磁铁矿、个旧锡多金属矿床、白牛厂超大型银多金属矿床、临仓超大型锗矿床、玉龙超大型铜矿床与川甘陕、滇黔桂微细粒浸染型金矿等。西南地区之所以有大量的矿产产出,与该区的峨眉地幔热柱活动密切有关(红阳等,2002)贵贞丰水银洞金矿位于峨眉地幔热柱活动区。通过研究发现水银洞金矿的成矿与峨眉地幔热柱的活动密切相关：成矿物质来源、含矿建造、热液活动与成矿作用等均与峨眉地幔热柱活动有在的联系。本文拟从地幔柱构造角度运用地幔柱理论、峨眉地幔热柱研究成果、水银洞金矿床研究成果探讨水银洞金矿成矿机理与成矿模式，对水银洞金矿成矿进行综合剖析和研究。本课题来源于贵省委组织部高层次人才特助经费项目峨眉地幔热柱活动与

44、黔西南卡林型金矿成因关系研究（TZJF-2006-05）1.1.2研究意义（1）学术意义自Morgan1971年提出热柱概念以来的三十余年里，人们对地幔柱构造理论的研究主要集中在以下几个方面：（1）地幔柱的理论研究：热点对地球表面的影响，热点与地幔柱的分类与分布，热点与地幔柱的热动力学研究等；（2）地幔柱理论运用:主要从区域上研究了与地幔柱活动有关的岩浆作用，成矿作用，超变质作用与构造等，如牛树银教授等研究了河淮地幔亚热柱的演化与其对华北地区成矿的控制作用。但目前鲜见有学者利用地幔柱构造理论研究某一具体矿床的成矿作用和成矿过程。水银洞金矿是黔西南地区最具代表性的卡林型金矿之一，许多单位与学者运

45、用多种研究手段和技术对它进行较为深入地研究，取得许多研究成果。目前水银洞金矿的研究大都停留在地壳围，多从矿床地质特征、矿床地球化学特征与成矿作用等方面探讨矿床成因，没有从地球深部（地幔）构造活动、岩浆构造活动角度深刻认识水银洞金矿的成矿过程。因此，本项研究以地幔柱构造理论为指南，以峨眉地幔热柱研究成果为支撑研究水银洞金矿床的成因具有创新性、开拓性的学术价值，该研究起到以点带面的作用，对其它矿床的成矿作用、成矿过程的认识具有借鉴作用，对于丰富和深化峨眉地幔热柱理论与其成矿作用具有重要理论意义。因此，本项研究具有重要的学术参考价值。（2）经济社会意义水银洞金矿在黔西南地区众多卡林型金矿床中具有突出

46、的地位：该金矿储量大，品位高，产出稳定，具有良好的找矿前景。贵是我国经济落后的地区之一，研究、寻找、开发该类型金矿床为推动地方经济发展具有重大现实意义；金矿作为重要的矿产资源，无论在工业、金融业还是在政治等方面都具有重要的地位，在保证国家经济健康稳定发展中有重大作用；随着人们物质文化生活水平的提高，对金等贵金属的需求量也越来越大。因此，研究、寻找该类型金矿床具有重大的现实意义。1.2本项研究容和方案1.2.1本论文的主要研究容（1）阐述峨眉地幔热柱活动理论研究现状、峨眉地幔热柱活动特征；（2）探讨峨眉地幔热柱活动形成水银洞金矿的地热背景、特殊的岩相古地理条件与含矿建造、成矿热液来源、成矿物质活

47、化迁移与成矿过程；（3）研究晚二叠纪以来峨眉地幔热柱活动对贞丰水银洞金矿床物质来源的贡献；（4）建立峨眉地幔热柱活动形成水银洞金矿床的成矿模式。1.2.2本论文的研究方案（1）收集峨眉地幔热柱研究资料、水银洞金矿资料，野外对水银洞金矿床进行调研，采集有代表性的样品进行相关分析测试；（2）论述在峨眉地幔热柱活动作用下，对黔西南地区区域地质背景的影响；（3）根据矿石的相关测试分析，探讨水银洞金矿成矿物质来源；（4）根据镜下鉴定、电子探针、扫描电镜、单矿物含金测试等研究成果，论述水银洞金矿床的物质组成特征、结构构造特征与金的赋存状态；（5）研究在峨眉地幔热柱活动作用下，水银洞金矿床的形成机理与过程；

48、（6）建立水银洞金矿床的成矿模式。1.2.3本次研究工作完成工作量（1）查阅相关文献资料完整100余篇，引用70余篇；（2）对黔西南进行区域地质调查两次，测制路线剖面10余条，水银洞金矿实地调查30余天；（3）采集代表性岩矿样品100余件，野外照片50余；（4）磨制光、薄片50余件，显微照相30余；（5）样品测试分析30余件；（6）发表学术论文两篇。1.3研究历史与现状20世纪70年代，贵地质矿产勘查开发局区调院首次在黔地区发现了册亨板其金矿，由此揭开了在黔西南地区寻找卡林型金矿的新篇章。在三十多年的时间里，贵地质矿产勘查开发局105、117、104、113、112与区调院、物化探院与测绘院等多家单位和许多地质工作者在该区系统地开展了1:20万区域地球化学测量、1:20万区域重力测量、1:5万区域地质调查与该区大部分地区的1:10万航空磁力测量等。通过这些系统扎实的地质工作，积累了大量的参考资料，提高了该区的