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1.
在"滇黔桂"、"川甘陕"两个金三角密集区内的一些卡林型金矿床中,存在毒砂、含砷黄铁矿、雄黄、雌黄等大量含砷矿物.尤为重要的是,在丫他、东北寨、金牙等金矿床中存在自然界中罕见的自然砷矿物,图1为金矿石中呈致密凝胶体状的自然砷.由于毒砂、含砷黄铁矿等矿物对于矿床地球化学类型的判别和成矿作用的物理化学条件具有重要的指示意义(God等,2000),因此砷矿物可作为卡林型金矿床的重要标型矿物.  相似文献   

2.
卡林型金矿床中的自然砷   总被引:2,自引:0,他引:2  
谭运金 《矿产与地质》2001,15(6):699-704
自然坤是金-砷-(锑)型金矿床的标型矿物,自然砷呈细粒状集合体和微细脉状产出,细粒状集合体产出的自然砷,其As、Au含量较高;微细脉状产出的自然砷,其Sb、S含量较高。本文根据成矿实验和矿物组合特征,讨论了含自然砷的金矿床的成矿温度和成矿过程的fo2、fs2的变化。  相似文献   

3.
根据文献报导及作者的研究,分别对Sedex型铅锌矿床、浅成低温热液金矿床、岩浆期后高温热液型石英脉状黑钨矿矿床和沉积岩为主岩的微细浸染型(卡林型)金矿床进行了矿床地球化学分类:Sedex型铅锌矿床分为Selwyn型矿床和McArthur型矿床,前者的成矿热卤水产生于开阔海盆或大陆斜坡的浊积岩建造,后者的成矿热卤水产生于氧化的海底裂谷沉积建造,浅成低温热液型金矿床分为酸性-硫酸盐型(明矾石-高岭石型)金矿床和冰长石-绢云母型金矿床,前一类金矿床的成矿流体,f(S2)和f(O2)较高,pH值较低,后一类金矿床的成矿流体,f(S2)和f(O2)较低,pH值较高.岩浆期后高温热液型石英脉状黑钨矿矿床分为钨-铍-钼-铋型黑钨矿矿床和钨-锡-硫化物型黑钨矿矿床,钨-铍-钼-铋型黑钨矿矿床的成矿作用是在pH值较高的弱碱性、Eh值较高的环境中进行的,钨-锡-硫化物型黑钨矿床的成矿作用是在pH值较低的弱酸性的,Eh值较低的环境中进行的.沉积岩为主岩的微细浸染型(卡林型)金矿床分为金-砷-(锑)型金矿床、金-汞-(铊)型金矿床和金-锑-黄铁矿型金矿床.金-砷-(锑)型金矿床的成矿流体是地层建造水(为主)与改造后的大气降水混合形成的热液,其pH值为3.6~5.2,且Eh值较低;金-汞-(铊)型金矿床的成矿流体是大气降水与地层建造水混合形成的热液,其pH值为5.0~7.5,Eh值较高;金-锑-黄铁矿金矿床的成矿流体是改造后的大气降水与岩浆演化成的流体混合形成的热液,其pH值为5.4~6.77,Eh值较高.  相似文献   

4.
捷克Jílové金矿集区在中世纪时期曾是波希米亚地块最大、最富集金的地区,黄金开采已具有2000多年的悠久历史。最重要的矿床有Pepˇr、Bohuliby、Radlík和Rotlev,主要赋存于新元古界těchovice组火山-沉积岩和波希米亚花岗闪长岩深成岩体中。金矿化存在3种类型:脉状矿化、含金网脉状矿化、浸染状矿化。金矿床中的矿物组成已超过70种,包括Cu、Pb、Zn、Fe、As、Mo、Bi、Hg、Au和Ag的一些硫化物、硫盐、氧化物、氢氧化物、硫酸盐、碳酸盐、钨酸盐、硅酸盐,还有碲化物、卤化物和自然元素的矿物。笔者通过显微镜观察、电子探针和扫描分析等综合分析技术,确认金矿床中也存在一些硒矿物。金矿石中的矿物种类较多,组成复杂以及存在大量碲化物、自然金,构成Jílové金矿集区的一大特色。一般说来,亲硫环境越强,出现硒化物、碲化物这样的特殊矿物就越少。因此,金矿床中同时存在大量碲化物、硒化物矿物,表明金矿床的形成具有特殊的物理化学条件。在成矿早阶段,具有高f(S2)和低f(Se2)、f(Te2)、f(O2)的介质,且f(S2)/f(Se2)>1、f(S2)/f(Te2)>1,此时形成大量的黄铁矿、白铁矿、磁黄铁矿、黄铜矿、毒砂、方铅矿、闪锌矿等硫化物。而Se、Te有可能以类质同象的形式赋存于硫化物矿物中。在成矿晚阶段,随着硫化物的大量沉淀,具有f(Se2)/f(S2)、f(Te2)/f(S2)、f(O2)逐渐增高,有利于硒化物、碲化物的形成。根据金矿石中的硒矿物、碲矿物组合,获得在300℃成矿温度下形成硒化物、碲化物时的f(Se2)、f(Te2)分别为10-14.97~10-7.09和10-10.98~10-7.50。  相似文献   

5.
自然界中的辉锑矿-硒锑矿矿物系列   总被引:3,自引:0,他引:3  
自然界中的辉锑矿-硒锑矿系列发现于西秦岭寒武系拉尔玛、邛莫金矿床中.与其密切共生的矿物有硒汞矿、硒铅矿、硒质块硫锑铜矿、硒镍矿、自然金以及石英、重晶石等.辉锑矿-硒锑矿系列的显微压力硬度为101.26~103 kg/mm2.主要元素的质量分数为:Sb 43.78%~73.81%,S 0.00%~28.76%,Se 0.00%~49.72%(但缺乏30.59%~43.04%之间的数据).根据电子探针分析数据中Se/(S Se)比值(原子比),可将所测矿物系列划分为(含硒质)辉锑矿、硒质辉锑矿、硫质硒锑矿和(含硫质)硒锑矿.矿物系列代表性的反射率(%):(470 nm)Rg'=42.62~47.62,Rp'=30.83~40.55;(550 nm)Rg'=41.84~46.75,Rp'=31.48~38.85;(590 nm)Rg'=42.25~46.63,Rp'=30.73~39.46;(650 nm)Rg'=43.30~46.48,Rp'=30.01~41.56.两个含Se量为3%~5%含硒质辉锑矿的晶胞参数值为:a=1.120 9~1.121 2 nm,b=1.129 9~1.130 3 nm,c=0.384 7~0.384 9 nm而硫质硒锑矿、硒锑矿的晶胞参数值分别为:a=1.159 1~1.159 3 nm;b=1.172 4~1.174 7 nm;c=0.394 1~0.398 4 nm.晶胞参数的变化与矿物中硫、硒含量变化密切相关.  相似文献   

6.
喜迎金矿床是新疆东南天山发现的一种新类型金矿,矿床产于下石炭统甘草湖组碳酸盐岩地层中.容矿岩石为含陆屑砂屑白云岩,矿石中金矿物以自然金为主,多呈微细粒包裹金.主要载金矿物为黄铁矿,呈细脉浸染状分布.成矿期分为4个阶段:黄铁矿石英白云岩阶段(Ⅰ)、金.黄铁矿一石英一碳酸盐脉阶段(Ⅱ)、黄铜矿一黄铁矿一石英阶段(Ⅲ)、石英-碳酸盐阶段(Ⅳ),通过矿区成矿地质特征、矿石矿物特征及成矿物理、化学特征综合分析,初步认为喜迎金矿床为卡林型金矿床。  相似文献   

7.
在内蒙拜仁达坝超大型Ag-Pb-Zn多金属矿床中,产出针硫锑铅矿。与其共生的金属矿物主要为方铅矿、银黝铜矿、磁黄铁矿、黄铜矿、块硫锑铅矿等。针硫锑铅矿呈长柱状、针状、毛发状、束状和不规则状等,粒度变化较大,一般为0.05~4mm,最大可达12mm。反光显微镜下为灰白色,强非均性,显微硬度VHN100g=93.25~127.39kg/mm2(平均111.05kg/mm2),相当于摩氏硬度3.06~3.40(平均3.24)。矿物主要化学成分质量分数为:Pb52.20%~57.80%(平均54.89%),Sb22.26%~28.13%(平均26.08%),S18.65%~19.62%(平均19.01%),并含有少量的Fe、Cu、Zn、Ag和As等元素。相应的平均化学分子式为(Pb4.91,Cu0.04,Fe0.03,Zn0.01)4.99(Sb3.97,As0.04)4.01S11.00,标准化学式为Pb5Sb4S11。晶体为单斜晶系对称,晶胞参数值a=2.156nm,b=2.349nm,c=0.810nm。矿床中针硫锑铅矿的形成,与成矿温度较低、硫逸度升高以及还原作用密切相关。  相似文献   

8.
甘肃大水闪长岩型金矿床的矿物地球化学特征   总被引:4,自引:0,他引:4       下载免费PDF全文
大水金矿氧化带下部,发育大量的微细粒浸染状、细脉状黄铁矿和黄铜矿,并出现砷黝铜矿.地表氧化矿中的赤铁矿,是黄铁矿等原生硫化物氧化所致;在矿石矿物成分上,黄铁矿、黄铜矿和砷黝铜矿的Au含量普遍较高.黄铁矿中的Co/Ni比值多大于2,与岩浆成因黄铁矿相吻合.流体包裹体均一温度为105℃~400℃.δ34S=-1.8‰~ 4.1‰,δ13C=-2.7‰~ 4.3‰,δ18O=6.63‰~19.42‰,δD=-101‰~-75‰.成矿流体主要来源于岩浆热液,碳、硫和成矿元素主要来源于赋矿闪长岩体,为富硫化物的闪长岩型金矿床.砷黝铜矿对找矿与勘探有指示作用.  相似文献   

9.
新疆萨热阔布金矿床流体包裹体研究及矿床成因   总被引:2,自引:0,他引:2  
新疆萨热阔布金矿床位于阿尔泰造山带南缘克兰火山-沉积盆地内,矿体呈脉状产于康布铁堡组上亚组地层中(D1k2)。不同成矿阶段石英脉中广泛发育流体包裹体,可划分为H2O-CO2包裹体(C型)、纯CO2包裹体(PC型)、水溶液包裹体(W型)及含子矿物多相包裹体(S型)四类。测温结果显示,成矿早阶段主要发育C型和PC型包裹体,均一温度范围为271~446℃,流体盐度介于5.9%~8.4%NaCleqv之间;中阶段主要发育C、PC、W和S型包裹体,均一温度低于早阶段,为236~374℃,流体盐度介于4.8%~15.0%NaCleqv之间;晚阶段主要发育W型包裹体,均一温度范围为139~264℃,流体盐度介于1.1%~6.9%NaCleqv之间。对成矿压力和深度的估算表明,成矿压力为90~330MPa,成矿深度为9~12km。综上所述,萨热阔布金矿成矿流体具有富CO2、中低盐度的变质流体特征,流体沸腾导致了成矿物质的沉淀。结合矿床地质特征,萨热阔布金矿床属于造山型金矿床。  相似文献   

10.
自然砷是比较稀少的矿物,纯净的自然砷更为罕见。它属于三方品系,为复三方偏三角面体对称型:L~33L~23PC。通常呈致密凝胶体状,常含有Sb、Fe、Ni、S和Ag等混入物。去年,笔者在对赣南大吉山钨矿床有关专题研究的分析测试中,经电子探针分析首次发现该矿床中有自然砷存在,它不仅粒度粗大,而且纯度极高。鉴于国内有关自然砷的研究报导甚少,而  相似文献   

11.
Geochemistry of hydrothermal gold deposits: A review   总被引:8,自引:0,他引:8  
Mineral assemblages formed during hydrothermal alteration reflect the geochemical composition of ore-forming fluids. Gold is mainly transported in solution as AueCl and AueS complexes. The change of physicochemical conditions such as temperature, pressure, oxygen fugacity, and sulfur fugacity are effective mechanisms for gold precipitation. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. AueAs and AueSb associations are common in gold deposit. Native antimony and/or arsenic e native gold assemblages may precipitate from hydrothermal fluids with low sulfur fugacity. Hydrothermal fluids forming epithermal gold deposits are Au-saturated in most cases, whereas fluids of Carlin-type are Au-undersaturated. Quasi-steady As-bearing pyrite extracts solid solution Au from hydrothermal fluids through absorption. The capability of As-bearing pyrite to absorb Au from under-saturated fluid is the key to the formation of large-scale Carlin-type deposits. With increasing new data, studies on the geochemistry of gold deposits can be used to trace the origin of ore-forming fluids, the source of gold, and the transporting form of Au and other ore-forming elements, such as Si, S, F, Cl, As and Ag.  相似文献   

12.
热液成矿作用地球化学:以金矿为例   总被引:7,自引:0,他引:7       下载免费PDF全文
文中以金矿为例总结了热液成矿地球化学特征,包括热液蚀变、金在成矿热液中的地球化学行为、富集-沉淀机制以及在硫化物中的存在形式。热液蚀变过程中形成的矿物组合反映了成矿流体的地球化学特征,蚀变模式具有重要的找矿勘探意义。在热液体系中,金主要以Au-Cl或者Au-S络合物的形式进行运移,体系温度、压力、氧逸度以及硫逸度等条件的变化是导致络合物分解、金沉淀的主要机制。在较高压力条件下,金趋向于在热液蒸汽相中富集。As和Sb是金矿热液体系中常见的伴生元素,在较低硫逸度条件下,形成自然砷/自然锑-自然金组合。金从热液中沉淀后主要以显微包裹体或者固溶体金的形式赋存于黄铜矿、毒砂、磁黄铁矿以及黄铁矿等硫化物中,而硫化物中固溶体金的量主要受热液H_2S活动性的控制。  相似文献   

13.
Element geochemistry of gold arsenic and mineralogical features of their sulfides in the Carlin-type gold depostis of the Qinling region are discussed in this paper.The initial contents of ore-forming elements such as glod and arsenic are high the ore-bearing rock series in the Qinling region.Furthermore,both the metals are concentrated mainly in the diagenetic pyrite.Study on the mineralogy of arsenic-bearing sulfide minerals in the ores demonstrated that there is a poistive correlation between gold and arsenic in the sulfide minerals.Available evidence suggests that gold in the As-bearing sulfide minerals in likely to be presented as a charge species(Au ),and it is most possible for it to replace the exxcess arsenic at the site of iron and war probably deposited together with arsenic as solid in the sulfide minerals. Pyrite is composed of(Aux^3 ,Fe1-2^2 )([AsS]x^3-[S2]1-x^2-),and arenopyrite of (Aux^3 ,Fe1-x^3 )([AsS]x^3-[AsS2]1-x^3-).The occurrence of glod in the As-sulfied minerals from the Carlin-type gold depostis in the Qinling region has been confirmed by electron probe and transmission electron microscopic studies.The results show that gold was probably depostied together with arsenicas coupled solid solutions in sulfide minerals in the early stage of mineralization.Metallogenic chemical reactions concerning gold deposition in the Carlin-type As-rich gold deposits would involve oxidation of glod and concurrent reduction of arsenic.Later,the deposited gold as solid was remobilized and redistributed as exsolutions,as a result of increasing hydrothermal alteration and crystallization,and decreasing resistance to refractoriness of the host minerals.Gold occurs as sub-microscopic grains(ranging from 0.04tp 0.16μm in diameter)of native gold along micro factures in and crystalline grains of the sulfiedes.  相似文献   

14.
万古金矿床位于江南造山带中部,赋存于新元古界冷家溪群浅变质岩系中,受NNE-NE向长沙-平江断裂带和近EW向九岭-清水韧性剪切带联合控制,金资源量约85t。其主要矿石类型为毒砂-黄铁绢英岩型和石英-硫化物脉型,其次为构造角砾岩型。毒砂和黄铁矿为该矿床主要的载金矿物,分布广泛。金成矿作用可分为四个阶段,I为乳白色石英-绢云母-白钨矿阶段;Ⅱ为烟灰色石英-绢云母-毒砂-黄铁矿-金阶段;Ⅲ为烟灰色石英-绢云母-黄铁矿-毒砂-多金属硫化物-金阶段;IV为乳白色石英-方解石阶段。其中,Ⅱ、Ⅲ为成矿主阶段。根据成矿主阶段毒砂电子探针分析结果,Ⅱ阶段毒砂中As的含量在42.19%~44.84%之间,均值为43.42%(n=56),Ⅲ阶段毒砂中As的含量在40.08%~43.36%之间,均值为42.08%(n=19)。通过毒砂温度计相图估算出Ⅱ、Ⅲ阶段的形成温度和硫逸度分别为364±21℃、319±22℃和10^(-9.7)~10^(-7)、10^(-11.5)~10_(-8.6)。电子探针数据揭示的载金毒砂和黄铁矿中不可见金含量分别为0.01%~0.66%和0.01%~0.11%。黄铁矿Au-As元素投点分布于金溶解度曲线两侧,说明其内金主要以纳米级颗粒和固溶体金或晶格金的形式赋存;其中Ⅱ阶段黄铁矿纳米级金颗粒占比为73.33%,多于Ⅲ阶段黄铁矿(67.80%)。以上数据说明在水岩反应过程中,围岩中的含铁矿物与成矿流体中的H;S发生反应,生成毒砂和黄铁矿。伴随着强烈的水岩反应,成矿温度和硫逸度降低,成矿Ⅱ阶段至Ⅲ阶段主要载金硫化物由毒砂转变为黄铁矿,强烈的硫化作用导致金-硫络合物失稳并释放金,金以置换的方式进入硫化物晶格或以显微-超显微金颗粒的形式沉淀,形成含金硫化物;即硫化作用是导致万古矿床不可见金沉淀的主导机制。  相似文献   

15.
成矿流体中碲逸度对自然金成色的影响   总被引:1,自引:0,他引:1  
富碲化物型金矿具有自然金成色高的特点,通过热力学分析,推导出碲逸度与温度和自然金中银含量的关系式,建立了fTe2-T-NAg图解,并论述了该类型金矿中高自然金成色的内在原因,即成矿溶液中高的碲逸度导致了高的自然金成色,同时也分析了溶液中碲逸度对金银矿物的共生组合的影响,以及对如何计算成矿溶液中碲逸度问题进行了讨论。  相似文献   

16.
不可见金的赋存状态研究   总被引:10,自引:0,他引:10  
毛永和 《矿物学报》1990,10(1):66-74,T007,T008
电子探针、扫描电镜和溶矿试验研究证明,在某地“卡林型”金矿中,黄铁矿是最主要的载金矿物。黄铁矿由先期形成的含Au和As很低的自形晶核心和后期形成的含Au和As很高的环边组成,其中Au和As呈正消长关系。因此,根据As的分布情况即可研究和认识Au的分布规律。研究结果为改善矿石的氧化焙烧、氯化处理和氰化浸出工艺设计提供了科学依据。  相似文献   

17.
Here we report the occurrence of some uncommon mineral assemblages including pääkönenite, aurostibite, native arsenic, native antimony, and native bismuth found in the Baogutu gold deposit in the western Junggar, Xinjiang, NW China. The mineralization could be generally subdivided into two types: the gold-bearing quartz-vein type mineralization and disseminated mineralization in the wall rocks. The sulfide minerals in gold lodes commonly include pyrite, arsenopyrite, marcasite, and stibnite. However, the L7 lode in No. 4 orebody and the L1 lode in No. 11 orebody of the Baogutu gold deposit are quite different in terms of their mineral assemblages. The L7 lode contains native arsenic–quartz veins in shallow levels and stibnite–quartz veins at depth. Gold-bearing minerals (electrum, native gold, and rarely aurostibite) mainly coexist with pääkönenite, stibnite, native arsenic, and native antimony. The crystallization of As- and Sb-bearing minerals was likely to have consumed H2S from the hydrothermal fluid, which probably triggered the precipitation of native gold. The L1 lode consists of several discontinuous sulfide-dominated lensoid orebodies. The massive sulfide ores that produced most of the gold resource are characterized by an intimate association between native bismuth and native gold mineralization.  相似文献   

18.
The Laloki and Federal Flag deposits are two of the many (over 45) polymetallic massive sulfide deposits that occur in the Astrolabe Mineral Field, Papua New Guinea. New data of the mineralogical compositions, mineral textures, and fluid inclusion studies on sphalerite from Laloki and Federal Flag deposits were investigated to clarify physiochemical conditions of the mineralization at both deposits. The two deposits are located about 2 km apart and they are stratigraphically hosted by siliceous to carbonaceous claystone and rare gray chert of Paleocene–Eocene age. Massive sulfide ore and host rock samples were collected from each deposit for mineralogical, geochemical, and fluid inclusion studies. Mineralization at the Laloki deposit consists of early‐stage massive sulfide mineralization (sphalerite‐barite, chalcopyrite, and pyrite–marcasite) and late‐stage brecciation and remobilization of early‐stage massive sulfides that was accompanied by late‐stage sphalerite mineralization. Occurrence of native gold blebs in early‐stage massive pyrite–marcasite‐chalcopyrite ore with the association of pyrrhotite‐hematite and abundant planktonic foraminifera remnants was due to reduction of hydrothermal fluids by the reaction with organic‐rich sediments and seawater mixing. Precipitation of fine‐grained gold blebs in late‐stage Fe‐rich sphalerite resulted from low temperature and higher salinity ore fluids in sulfur reducing conditions. In contrast, the massive sulfide ores from the Federal Flag deposit contain Fe‐rich sphalerite and subordinate sulfarsenides. Native gold blebs occur as inclusions in Fe‐rich sphalerite, along sphalerite grain boundaries, and in the siliceous‐hematitic matrix. Such occurrences of native gold suggest that gold was initially precipitated from high‐temperature, moderate to highly reduced, low‐sulfur ore fluids. Concentrations of Au and Ag from both Laloki and Federal Flag deposits were within the range (<10 ppm Au and <100 ppm Ag) of massive sulfides at a mid‐ocean ridge setting rather than typical arc‐type massive sulfides. The complex relationship between FeS contents in sphalerite and gold grades of both deposits is probably due to the initial deposition of gold on the seafloor that may have been controlled by factors such as Au complexes, pH, and fO2 in combination with temperature and sulfur fugacity.  相似文献   

19.
现代金成矿地球动力学的研究,揭示了矿床及其组合与构造变动、岩浆活动一样,是地壳变革的一个事件,因此从成矿环境地质方面可反演矿床及其组合的形成史,正确划分出与区域地壳演化阶段相适应的矿化类型;滇黔桂卡林型金矿的形成与右江幔隆的发生、发展息息相关,本文借用金成矿地球动力学的一些思想,用地幔隆起的观点分析了本区卡林型金矿的形成。  相似文献   

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