型锌-铅-银矿床课件.pptx

1、Zn-Pb-Ag ores in Clastic-Dominated Sediments(SEDEX)SEDEX型锌型锌-铅铅-银矿床银矿床 Most in Passive Margin sequences,a few in marine-filled continental back arc or rift basins大多数发育在被动大陆边缘，少量分布在充满海水的大陆弧后或裂陷盆地中大多数发育在被动大陆边缘，少量分布在充满海水的大陆弧后或裂陷盆地中Genesis,Attrition and Life Cycle of Passive Margins被动大陆边缘的形成、消减和活动旋回被动大陆

2、边缘的形成、消减和活动旋回Evaporative Factories:Passive margins andocean closure basins蒸发岩的生产工厂：被动陆缘和大洋闭合盆蒸发岩的生产工厂：被动陆缘和大洋闭合盆地地 Wilson Cycle of Ocean Basins大洋盆地的威尔逊旋回大洋盆地的威尔逊旋回Transitional tectonic example of passive marginBack Arc basin被动大陆边缘的铅锌矿被动大陆边缘的铅锌矿远离活动板块边缘。远离活动板块边缘。火山火山活活动较弱动较弱。例子：美国东海岸例子：美国东海岸大陆边缘大陆边缘深

3、海扇深海扇浊积岩浊积岩深海平原深海平原洋壳洋壳大陆坡大陆坡大陆隆大陆隆大陆架大陆架水下峡谷水下峡谷陆架边缘陆架边缘大陆壳大陆壳离散边缘（初始裂谷）的高角度正断层离散边缘（初始裂谷）的高角度正断层巨巨厚沉积物厚沉积物泥泥砂砂碳酸盐和硅质软泥碳酸盐和硅质软泥Example of Passive Margin CD formed by sub-seafloor replacement processes 被动大陆边缘典型实例，被动大陆边缘典型实例，经经海底交代作用形成海底交代作用形成Fate of passive margins to be involved in plate collisions-

4、complex tectonic and post ore deformation 被动大陆边缘会经历板块碰撞、复杂被动大陆边缘会经历板块碰撞、复杂的构造及成矿的构造及成矿后形变后形变Red Dog:Cold methane seep on Carboniferous sea floor,barite and carbonate turbidites replaced by Zn-Pb event,buried to 12 km in Cretaceous and silicified 红狗矿床：石炭纪红狗矿床：石炭纪海底有低温甲烷海底有低温甲烷渗出体；重晶石和碳酸盐浊流沉积渗出体；重晶石和碳

5、酸盐浊流沉积岩被岩被Zn-Pb交代交代，随后在，随后在白垩纪被深埋白垩纪被深埋12km，并被，并被硅化。硅化。Red Dog Deposit:Worlds Largest Zn DepositSub-seafloor replacement红红狗：世界最大的锌矿床狗：世界最大的锌矿床海底深部的交代作用海底深部的交代作用Frequency13.918.6012345670-2-4-6-8-10-12-14-16050010001500050010001500Cl/BrNa/BrSeawaterGYPNaClMgSO4K saltsTemperatureWt.%NaCl eqv.RED DOG O

6、RE FLUIDSCarboniferous Basin Configuration 石炭纪石炭纪盆地盆地形态形态50 Miles50 Miles.+v vv vv vv vv vv v OceanHighlandsTidalShallow Marine Shallow Water Platform CarbonatesOld Crustal Block Angayucham OceanOld Crustal BlockN FaultRed DogAnoxic or dysoxicshalesOxic/Anoxic chert/shales高地高地潮汐区潮汐区浅海浅海浅水台地碳酸盐浅水台地碳酸

7、盐缺氧页岩缺氧页岩老老地壳地壳块体块体洋洋断层断层Why are some passive margins fertile and others not?为什么一些被动陆缘富集而其他的为什么一些被动陆缘富集而其他的却不富集？却不富集？Reflux ofcoastal brines沿岸卤水的回沿岸卤水的回流流Jones et al.,2002Leach et al.,2005;2010From Kelley and Jennings(2004)Age=338+/-5 MaSNQanaiyaqMainAqqalukPaalaaqFully lithified black muds Relative

8、ly oxidized brines with Fe,Pb,and ZnSeawaterStage 3:Deposition of barite and RBS in veins and replacement of barite第三阶段：重晶石和第三阶段：重晶石和红棕色闪锌矿在脉中红棕色闪锌矿在脉中沉积；重晶石被交代。沉积；重晶石被交代。Thermal alteration of mudstone produces methane;hydrofracturing and vein formation occurs海水海水完全成岩的黑泥完全成岩的黑泥泥岩的热交代产生甲烷；发生水动力破裂；脉体形

9、成泥岩的热交代产生甲烷；发生水动力破裂；脉体形成相对氧化的盐水，含相对氧化的盐水，含Fe,Pb,ZnEWMS3 cmMassive early barite+early sulfide replacement块块状状矿矿石中早期重晶石石中早期重晶石+早期硫化物交代作用早期硫化物交代作用200 minterstitialAvg d d3434S of 3.3 =TSR of seawater sulfate in pore water or pre-existing barite 平均平均d d3434S 3.3 =空隙空隙水或水或已存在的重晶石中海水硫酸盐的热化学还已存在的重晶石中海水硫酸盐的

10、热化学还原是矿石中硫的主要来源原是矿石中硫的主要来源Higher Fe(4%);lower Mn(30%salinity:Dynamic brine source!矿质流体：盐度矿质流体：盐度30%，动态卤水源区，动态卤水源区 Temp 150 to 200C?温度：温度：150200?Concentrated source of sulfur:barite 硫已经富集：重晶石硫已经富集：重晶石 Organic matter abundant:reductant for sulfate(seawater and barite)and preservation of ore 富有机质：硫酸盐富有

11、机质：硫酸盐(海水及重晶石海水及重晶石)的的还原剂，有利于矿石的保留还原剂，有利于矿石的保留 Oxidized clastic aquifer 氧化的碎屑岩含水层氧化的碎屑岩含水层 Focused into confined carbonate turbidites 集中在封闭的碳酸盐质浊沉岩中集中在封闭的碳酸盐质浊沉岩中 Long lived fluid system 长期活动的长期活动的流体体系流体体系 Silicification and upgrading 硅化及品位提高硅化及品位提高Zn-Pb CD Deposits in Marine-Filled Continental Back

12、 Arc Basins of North Australia and the Sullivan Deposit in the Belt-Purcell Basin,North America澳大利亚北部海水覆盖的大陆弧后盆地中澳大利亚北部海水覆盖的大陆弧后盆地中SEDEX型锌铅矿床和北美型锌铅矿床和北美Belt-Purcell盆地中的盆地中的Sullivan矿床矿床+Passive margin environment in marine-filled continental back arc basinMt IsaHYCCenturyCentury Mine,North AustraliaC

13、onventional Interpretation:Rift-Sag basins 通常的解释：裂陷盆地New interpretations:Passive margin environments of marine-filled continental back arc basins 新的解释：海水覆盖的大陆弧后盆地中被动边缘环境In Large et al.,2005McArthur BasinKorsch et al.,2011Nuna break-up:North Australian Basin systemNuna超大陆裂解超大陆裂解：澳大利亚北部盆地体系澳大利亚北部盆地体系C

14、ourtesy P SouthgatePlatform faciesBasinal faciesHilton-George FisherMt Isa-typeBroken Hill-typeDominantly deep water turbiditesVery minor carbonateMainly shallow water or sub-areal environmentAbundant carbonateFrom Southgate,et al.,2013Passive margin sequence of “back arc basin”.Closure and metamorp

15、hism during Isan Orogeny ca.1640 Ma主要为深海环境的浊积岩，只有非常少量的碳酸盐岩主要为浅海环境，出现大量的碳酸盐岩“弧后盆地”中被动 边缘层序Major Fault Control on Fluid Flow Tawallah Group010 kmto BorroloolaEmu Fault ZoneHYCCalvert FaultHot Springs FaultTawallah Fault13600E1630SBatten TroughFrom Large,2006Current Model for Century(from Broadbent et

16、al.,2002)From Ross Large et al.,2005A model for McArthur River一一个个McArthur河河矿矿床的成床的成矿矿模型模型 Active deformation formed flower structure that was accompanied by syn-ore deformation coeval folding of ores and sedimentary breccias 构造变形形成花状构造，伴随矿体形变，同构造变形形成花状构造，伴随矿体形变，同时导致矿石沉积角砾的褶皱时导致矿石沉积角砾的褶皱 McArthur Ri

17、ver formed in pull-apart basin associated with strike-slip Emu fault system active during break-up of Nuna Supercontinent McArthur River矿床形成于矿床形成于Nuna超大陆裂超大陆裂解中形成的解中形成的EmuEmu走滑断裂体系所导致的拉分走滑断裂体系所导致的拉分盆地中盆地中 Mineralisation largely diagenetic Metals(Cooke et al.,2001)and hydrocarbons(Williford et al.,20

18、09)derived from upper Tawallah Group 金属和碳氢化合物来源于金属和碳氢化合物来源于Tawallah组组 Mineralisation distal expression of 1640 Ma Liebig Orogeny成矿远离造山运成矿远离造山运动动From Huston,2010 http:/epress.anu.edu.au/titles/shaping-a-nationSullivan hot reduced sediment-fill,fluid can be acidic set apart from typical CDs Sullivan矿床

19、-充填热的还原性沉积物，酸性流体，与典型的CD矿床不同 Also see John Lydon GSC WebLydon,2007Belt-Purcell Basin:Thick reduced rift sequence and more oxidized upper sequence:high heat flowBelt-Purcell盆地：盆地：厚的还原性裂厚的还原性裂谷地层层谷地层层序和更氧化的上序和更氧化的上部层序：高热流值部层序：高热流值 Sullivan Mine cross section Sullivan矿矿床床剖面剖面排水口建造排水口建造成成层层的的矿矿石石白云母（白云母（

20、绢绢云母）云母）绿绿泥石泥石-钠长钠长石石-黄黄铁矿铁矿-(方解石方解石)绿绿泥石泥石-雌黄雌黄铁矿铁矿电电气石气石致密致密块块状状矿矿石石辉长辉长岩和岩和“花斑岩花斑岩”辉长辉长岩岩岩岩墙墙和岩床岩枝和岩床岩枝未未蚀变蚀变的沉的沉积积岩岩Sullivan Mine,British Columbia,CanadaSullivan矿矿床床，British Columbia省，加拿大省，加拿大闪锌矿闪锌矿和和磁黄磁黄铁矿铁矿互互层层的的闪锌闪锌矿矿和泥和泥质质岩岩泥泥质质岩岩Lydon,2007Northeastern margin of the Purcell basin in Fort Ste

21、ele and Aldridge Times(Hy,1983)Fort Steele 和和Aldridge Times地区地区Purcell 盆地的北东边界盆地的北东边界Exploration for CD DepositsSEDEX矿床的勘查矿床的勘查Passive margins from Bradley,2008Permissive Belts:evaporites,carbonates,passive margins in evaporative belts,rich in Organic matter可能的带：蒸发岩、碳酸盐岩、蒸发岩带的被动边缘、富含有机质可能的带：蒸发岩、碳酸盐岩

22、、蒸发岩带的被动边缘、富含有机质abExploration:Passive Margins and stratigraphic sectionBradley,2008USGS Circular 1319Stratigraphic Locations of Sulfide and Barite Deposits for the Central Brooks RangeCentral Brooks Range 地区硫化物和重晶石矿床的层状地区硫化物和重晶石矿床的层状展布展布Extensive stratibound Fe-Mn Carbonate Halos普遍的层控普遍的层控Fe-Mn碳酸盐晕碳酸盐晕 siderite-ankerite-ferroan dolomite-dolomite菱铁矿-富铁白云石-含铁白云石-白云石 extensive Mn,Tl and Sr isotope halos普遍的Mn，Tl和Sr同位素晕From Large,2006Metamorphosed alteration can be important:Zn Garnets,siderite to magnetiteTrace elements in CD deposits(Leach et al.2005)KeyElements Tl Mn As Sb Ba