湘西—黔东汞矿带硒的赋存特征

在湘西－黔东汞矿带中，硒主要替代硫以类持同象的形式存在辰砂中，少部分见于黑辰砂的硒汞矿中，辰砂中硒含量的高低与其颜色，晶形，粒度，生成期以及产出部件有关，硒是湘黔汞矿带标型微量指示元素。     

邛莫金矿床中的灰硒汞矿

灰硒汞矿是一种少见的矿物。该文叙述的灰硒汞矿产于西秦岭南亚带邛莫微细浸染型金矿床中。与其共生的矿物有自然金、灰硒铅矿、硒锑矿、硒镍矿、硒－辉锑矿、硒－块硫锑铜矿、硒－辉砷镍矿等。     

我国甘肃硒汞矿的发现及研究

硒汞矿产于甘肃省拉尔玛金矿床中,主要共生矿物有石英、重晶石、辉锑矿、黑辰砂、自然金等。硒汞矿呈铅灰色到黑色,金属光泽,性脆。粒度0.01～0.36mm。比重D=8.27,摩氏硬度2.5。电子探针定量分析结果的平均值(%):Hg 71.50,Se 25.21,S 1.88,Au 0.19,Ag 0.07,Te 0.09,As 0.06,Sb 0.04,Fe 0.04,总和99.08。空间群。a=0.6081(1)nm,Z=4。     

湖南保靖东坪汞矿中的含硒黑辰砂

含硒黑辰砂产于寒武系含碳泥质显微晶粒白云岩中。赋存在石英脉中及硅化较强的地段。矿石以含硒黑辰砂为主,其他共生矿物有黄铁矿、硫汞锌矿、辰矿、黝铜矿。含硒黑辰砂属等轴晶系。呈深灰色。条痕黑色。比重7.96。反射色为白色带蓝灰。反射率为28.5(480),27.5(540),26.7(580),26.2(640)％。化学成分为Hg=84.04,Se=4.23,S=11.02％。X射线粉晶衍射主要数据为3.436(100),2.977(37),2.106(57),1.997(37)。晶胞参数α=0.5899nm     

贵州及邻省区与蒸发岩和油气有关的汞矿成矿物理化学条件

对区域汞矿床中辰砂及其共生的脉石矿物的同位素组成和矿物包裹体成分的研究，讨论了所论汞矿成矿的物理化学条件。结合四川、重庆等地现代卤水（黄卤、黑卤）的对比研究和分析，认为黄卤和黑卤是具有成矿潜力的封存热卤水。     

湘西硒汞矿矿物学特征

硒汞矿是自然界一种少见的矿物,我国产地不多,80年代初仅在湖北随南地区和湖南新晃上关溪有所发现。笔者近年在保靖东坪和衡东石峡矿区也发现了硒汞矿。在这三个产地中,又以新晃上关溪规模最大,可形成独立硒矿体,其余两处均与辰砂少量共生。早在80年代,黄金五一六部队就对上关溪硒汞矿作了初步研究。1990年地科院陈殿芬等又进一步作了深入的研究;同一时期,笔者也对三处产地的硒汞矿作了详细的矿物学研究。 1 产出特征上关溪硒汞矿床位于湘黔汞矿带新晃酒店塘大型汞矿床的外围,属典型的层带式层控汞矿床。含矿地层系中寒武统敖溪组顶部硅化白云质灰岩。硒汞矿已形成独立矿体,多呈不规则     

贵州汞矿与地质构造

我国汞矿资源丰富,汞矿储量和开采量都居世界的前列。其中贵州汞矿占了较大比重,独具特色。根据构造控矿的科学理论和大量的实际资料及考察。实践证明:贵州汞矿的分布和汞矿带、矿田、矿床的产出都与地质构造关系密切。贵州汞矿可划分为五个汞矿构造域、28个汞矿带和7个汞矿化带。另按矿床产出的构造形态特征划分为整合类型、断裂类型和综合类型,这一划分旨在指导汞矿的地质普查和勘探工作。     

万山汞矿区汞质沉积成因研究

万山汞矿是典型的层控矿床,属沉积改造成因。矿质主要来自围岩。从寒武纪初至寒武纪末,形成了一个完整的沉积成矿系列,即形成磷、镍、钒、银、钾、汞、铅、锌、金等的沉积或沉积改造矿床。不仅在沉积岩中,而且在一些典型的沉积矿物、生物化石、生物礁中都有高丰度的汞、铅、锌、砷、锑,在三叶虫化石中含汞最高达100ppm。从矿物的结构构造特征方面也可找到沉积汞的证据,典型的沉积辰砂与热液辰砂大有区别,并发现极少数微粒辰砂赋存在透镜状褐铁矿结核的中心。各方面的资料说明,沉积岩中分散状态的汞质是沉积成因的。     

我国主要汞矿床的辰砂硫同位素组成

汞矿是我国重要有色金属矿产之一,和世界相比,有其独特之处。据26个汞矿床(点)229件辰砂硫同位素测定值统计,绝大部分辰砂的δ~(34)S都是正值,且与含矿地层中硫酸盐δ~((?)4)S的差值,大致有一个确定的变化范围。辰砂的δ~(34)S比含矿地层中硫酸盐的δ~(34)S平均低9.35‰。从时间的总体上看,各时代地层中辰砂的δ~(34)S变化曲线与海洋硫酸盐的δ~(34)S时间变化曲线,几乎具有相同的演化趋势。因而,在一般情况下,辰砂中的硫都是来自含矿地层中的海洋硫酸盐。     

陕西汞矿类型简介兼论金—汞矿床的找矿前景

在综合归纳秦岭泥盆系多金属矿带特征的基础上,将陕西汞矿床划分为三种类型,即层控型、裂隙脉状型和伴生型;分析了金汞元素的矿物和地珠化学相似性,金汞矿床共生成矿特征,认为陕西境内秦岭地区是金—汞找矿的有利地区.     

Sulphide and oxide minerals from the Ohmine granitic rocks in Kii Peninsula,central Japan,and their primary paragenetic relations

In the Ohmine granitic rocks of Kii Peninsula, central Japan, ilmenite, rutile, pyrrhotite, pyrite and chalcopyrite commonly occur, but no magnetite is present. Their primary paragenetic relations were confirmed by examining their mode of occurrences as inclusion species in major silicate minerals and the phase relations in the Cu-Fe-S system, though their parageneses changed in cooling of the rocks. This makes it possible to estimate the fugacities of oxygen and sulfur in the granitic rocks based upon their paragenetic relations, and to discuss the nature of volatiles in the granitic rocks. Significant subsolidus reactions for sulfide minerals continued until the rocks cooled below 300° C and took place in two types of mineral grains, in groundmass and as inclusions. The removal of sulfur and copper through the silicate crystals was too easy to preserve the chemistry of sulfides included in silicates.     

The source of sulfur in sulfide deposits in the Siberian Platform traps (from isotope data)

The source of sulfur in giant Norilsk-type sulfide deposits is discussed. A review of the state of the problem and a critical analysis of existing hypotheses are made. The distribution of δ³⁴S in sulfides of ore occurrences and small and large deposits and in normal sedimentary, metamorphogenic, and hypogene sulfates is considered. A large number of new δ³⁴S data for sulfides and sulfates in various deposits, volcanic and terrigenous rocks, coals, graphites, and metasomatites are presented. The main attention is focused on the objects of the Norilsk and Kureika ore districts. The δ³⁴S value varies from -14 to + 22.5‰ in sulfides of rocks and ores and from 15.3 to 33‰ in anhydrites. In sulfide-sulfate intergrowths and assemblages, δ³⁴S is within 4.2-14.6‰ in sulfides and within 15.3-21.3‰ in anhydrites. The most isotopically heavy sulfur was found in pyrrhotite veins in basalts (δ³⁴S = 21.6‰), in sulfate veins cutting dolomites (δ³⁴S = 33‰), and in subsidence caldera sulfates in basalts (δ³⁴S = 23.2-25.2‰). Sulfide ores of the Tsentral’naya Shilki intrusion have a heavy sulfur isotope composition (δ³⁴S = + 17.7‰ (n = 15)). Thermobarogeochemical studies of anhydrites have revealed inclusions of different types with homogenization temperatures ranging from 685 °C to 80 °C. Metamorphogenic and hypogene anhydrites are associated with a carbonaceous substance, and hypogene anhydrites have inclusions of chloride-containing salt melts. We assume that sulfur in the trap sulfide deposits was introduced with sulfates of sedimentary rocks (δ³⁴S = 22-24‰). No assimilation of sulfates by basaltic melt took place. The sedimentary anhydrites were “steamed” by hydrocarbons, which led to sulfate reduction and δ³⁴S fractionation. As a result, isotopically light sulfur accumulated in sulfides and hydrogen sulfide, isotopically heavy sulfur was removed by aqueous calcium sulfate solution, and “residual” metamorphogenic anhydrite acquired a lighter sulfur isotope composition as compared with the sedimentary one. The wide variations in δ³⁴S in sulfides and sulfates are due to changes in the physicochemical parameters of the ore-forming system (first of all, temperature and P_ch4) during the sulfate reduction. The regional hydrocarbon resources were sufficient for large-scale ore formation.     

Thermodynamics of Arsenates,Selenites, and Sulfates in the Oxidation Zone of Sulfide Ores. XIV. Selenium Minerals in the Oxidation Zone of the Yubileynoe Massive Sulfide Deposit,the South Urals

Selenium is one of the most important minor elements in massive sulfide ores. This study focuses on selenium minerals present in the oxidation zone of the Yubeleinoe massive sulfide deposit, the South Urals, Russia: clausthalite (PbSe), tiemannite (HgSe), and naumannite (Ag₂Se). These minerals are associated with goethite and siderite. Thermodynamic modeling was used to estimate the physicochemical parameters of selenide stability and the possible formation of Pb, Hg, and Ag selenites as a result of sulfide ore oxidation. The Eh–pH diagrams for the Fe–S–CO₂–H₂O and Fe–Se–CO₂–H₂O systems were calculated to estimate the physicochemical formation conditions of the Yubileinoe oxidation zone, as well as for the M–Se–Н₂О and M–S–H₂O (M = Hg, Pb, Ag) systems. The physicochemical parameters of clausthalite, naumannite, and tiemannite stability are consistent with these conditions. Only the formation of PbSeO3 is theoretically possible among Pb, Ag, and Hg selenites.

     

Platinum-group elements in the Merensky reef. I. PGE in solid solution in base metal sulfides and the down-temperature equilibration history of Merensky ores

 The platinum-group elements (PGE) in base metal sulfides (BMS) of the Merensky reef are mostly close to the detection limit of the proton microprobe. The only phase that accommodates appreciable PGE is pentlandite. Total average PGE plus Au grades of the sulfide fraction of the Merensky reef are about 500 ppm. We estimate the modal proportions of the major BMS to be around 53 percent pyrrhotite, 25 percent pentlandite, and 22 percent chalcopyrite (ignoring minor phases). Using this estimate, we calculate by how much the sulfides are oversaturated with respect to individual PGE. With respect to Pt, the sulfides are many times oversaturated, i.e., nearly all Pt occurs as discrete PGE phases. With regard to Pd the sulfides are oversaturated by about a factor of two. The Ru and Rh levels are at and below saturation levels. Available experiments suggest that the entire PGE content of the sulfide fraction can easily be accommodated in solid solution in BMS at temperatures as low as 500°C. The fact that the BMS are oversaturated with most PGE thus indicates that the sulfides have continued to exsolve PGE below that temperature. Calculated sulfur fugacities indicate that f _S2 is controlled by silica activity, as expected in high-temperature ores, suggesting that metal/sulfur ratios of the ore may not have changed much since complete solidification of the intercumulus silicate melt of the Merensky reef. All sulfides investigated have cooled below the maximum temperature of pentlandite-pyrite coexistence, which experiments place at 250±30°C. Final closure temperatures of the sulfide-PGE mineral assemblages, approximated by extrapolating the pentlandite-pyrrhotite solvus beyond its experimentally determined range, are possibly as low as 80 to 90°C. Received: 25 April 1995/Accepted: 5 September 1995     

The problem of genesis of gold and silver sulfides and selenides in the Kupol deposit (Chukotka,Russia)

Gold and silver minerals from the Kupol epithermal deposit, Chukotka, were studied. A schematic sequence of mineral formation has been compiled. Specific mineral assemblages have been revealed in jarosite breccias: with native gold, uytenbogaardtite, fischesserite, acanthite, and native sulfur. We considered a possible mechanism of formation of gold and silver sulfides and selenides in volcanogenic deposits: They might have formed during solfatara and postsolfatara processes with the participation of volcanic gases or their condensates and sublimates as well as liquid sulfur (and selenium) and sulfuric hydrotherms produced under the interaction of volcanic gases with meteoric waters. The specific features of the Kupol deposit confirm the solfatara genesis of Au–Ag sulfides and selenides.     

A sulfur isotope study on pyrite deposits of Southern Tuscany,Italy

The S-isotope composition (δ³⁴S_CDT) of 213 samples of sulfides, sulfates and native sulfur from the pyrite mineralizations of southern Tuscany and associated country rocks were determined. The sulfur isotopic composition of pyrite is quite homogeneous and similar for all studied ore bodies, with an average δ³⁴S value near +9,5‰. Pyrite disseminated within the Filladi di Boccheggiano formation, and thought to be authigenic, shows a much larger range of δ³⁴S values (-13.1 to +14.5‰). The isotopic compositions of other sulfides associated with pyrite in the deposits show that isotopic equilibrium among sulfides was approached on a regional scale, but seldom fully attained. Isotopic data suggest that sedimentary marine sulfate was the ultimate source of sulfur in ores. Sulfates (mostly anhydrite) from the sulfate-carbonate lenses associated with both the Filladi di Boccheggiano and the Calcare Cavernoso formations also have similar and homogeneous compositions (average δ³⁴S=+15–16‰). Coexisting sulfates and sulfides are not in isotopic equilibrium. In the light of the isotopic data, among the many proposed genetic models for the largest stratabound pyrite bodies the two following alternatives appear the most likely: 1) in agreement with recently suggested hypotheses, the ore bodies are older than the emplacement of the Mio-Pliocenic granitoids in the area, and are probably hydrothermal-sedimentary in origin, coeval with associated country rocks; 2) the ore bodies were formed as a consequence of bacterial reduction of anhydrite in low-temperature convection systems related to the early stages of the Mio-Pliocenic thermal anomaly. In both cases, the emplacement of the Mio-Pliocenic granitoids caused metamorphism and remobilization of the pre-existing ores, producing smaller discordant mineralized bodies.     

攀西裂谷地区层状镁铁岩的PGE矿化作用

攀西裂谷位于四川西部,裂谷经历了元古宙和海西期二次地幔柱活动,形成多处穹窿构造和层状镁铁质岩体的侵入。后一期的层状岩体赋存著名的超大型钒钛磁铁矿床。中国和南非合作研究认为,层状岩体PGE矿化应进一步研究。以新街岩体为代表,经钻探工程建立了岩体剖面;岩石学、矿物学和地球化学研究证实,岩体有三个岩浆旋回和许多韵律层,层厚仅2~3cm。自上而下岩相为辉长岩、橄辉岩、辉石岩和橄榄岩,造岩矿物为贵橄榄石、普通辉石、钛普通辉石和中长石。岩体下部旋回,硫化物较富集,多在高镁质岩相。硅酸盐、氧化物和硫化物三系列矿物共生而不混熔。硫化物呈浸染状,主要有三层,产在橄榄岩、辉石岩和下辉长岩内。铂族矿物有砷铂矿、自然铂、硫锇矿、铋碲钯矿、碲铋矿、碲银矿、自然银等。PGE富集可能有三个阶段:岩浆早期,岩浆中"S"不饱和,PGE易进入硅酸盐;岩浆晚期"S"逸度增高,硫化物富集,为PGE富集阶段;热液阶段PGE再分配富集。PGE和Ni、Cu、S为正相关关系,和Fe、Ti相辅相成,无明显关系。岩石中PGE背景值为(0.166~0.411)×10-6,PGE矿化体的品位变化较大,为(0.94~0.976)×10-6。有的钻孔样品Pt+Pd含量大于1×10-6,可做进一步找矿的依据。     

Sulfide-associated mineral assemblages in the Bushveld Complex, South Africa: platinum-group element enrichment by vapor refining by chloride–carbonate fluids

The petrology of base metal sulfides and associated accessory minerals in rocks away from economically significant ore zones such as the Merensky Reef of the Bushveld Complex has previously received only scant attention, yet this information is critical in the evaluation of models for the formation of Bushveld-type platinum-group element (PGE) deposits. Trace sulfide minerals, primarily pyrite, pyrrhotite, pentlandite, and chalcopyrite are generally less than 100 microns in size, and occur as disseminated interstitial individual grains, as polyphase assemblages, and less commonly as inclusions in pyroxene, plagioclase, and olivine. Pyrite after pyrrhotite is commonly associated with low temperature greenschist alteration haloes around sulfide grains. Pyrrhotite hosted by Cr- and Ti-poor magnetite (Fe₃O₄) occurs in several samples from the Marginal to Lower Critical Zones below the platiniferous Merensky Reef. These grains occur with calcite that is in textural equilibrium with the igneous silicate minerals, occur with Cl-rich apatite, and are interpreted as resulting from high temperature sulfur loss during degassing of interstitial liquid. A quantitative model demonstrates how many of the first-order features of the Bushveld ore metal distribution could have developed by vapor refining of the crystal pile by chloride–carbonate-rich fluids during which sulfur and sulfide are continuously recycled, with sulfur moving from the interior of the crystal pile to the top during vapor degassing.     

Gold-Related Sulfide Mineralization and Ore Genesis of the Penjom Gold Deposit, Pahang, Malaysia

The Penjom gold deposit lies on the eastern side of the Raub‐Bentong Suture line within the Central Belt of Permo‐Triassic rocks, near Kuala Lipis, Pahang, Malaysia. The geology of the deposit is dominated by a sequence of fine‐ to coarse‐grained rhyolitic to rhyodacitic tuff, tuff‐breccia and a minor rhyolitic–rhyodacitic volcanic series, associated with argillaceous marine sedimentary rocks consisting of shale with subordinate shalely limestone of Padang Tungku Formation and Pahang Volcanic Series. Fine‐ to coarse‐grained tonalite and quartz porphyry intruded this unit. The main structural features of the area are north–south‐trending left‐lateral strike‐slip faults and their subsidiaries, which generally strike north–south and dip moderately to the east (350°–360°/40°–60°). Mineralization at the Penjom gold deposit is structurally controlled and also erratic laterally and vertically. The gold mineralization can be categorized as (i) gold associated with carbonate‐rich zones hosted within dilated quartz veins carrying significant amount of sulfides; (ii) gold disseminated within stockwork of quartz–carbonate veins affiliated with tonalite; and (iii) gold often associated with arsenopyrite and pyrite in quartz–carbonate veins and stringers hosted within shear zones of brittle–ductile nature in all rock types and in brittle fractured rhyodacitic volcanic rocks. Sphalerite, chalcopyrite, tetrahedrite and pyrrhotite are the minerals accompanying the early stage of gold mineralization. These minerals also suffered from local brittle deformation. However, most of the gold mineralization took place after the deposition of these sulfides. Galena appears somewhat towards the end of gold mineralization, whereas tellurium and bismuth accompanied gold contemporaneously. The gold mineralization occurred most probably due to the metamorphogenic deformational origin concentrated mostly in the shear zone. The mineralization is strongly controlled by the wall rock (e.g. graphitic shale), the sulfide minerals and fluid–rock interaction.     

Distribution,occurrence and enrichment mechanism of key metals of selenium,tellurium and cobalt in Wushan copper deposit,Jiurui ore concentration area,Jiangxi ProvinceSCIEI北大核心CSCD

武山铜矿床是长江中下游成矿带九瑞矿集区内典型的层控-接触带矽卡岩型铜多金属矿床,铜资源量达到大型,此外还共生硒、碲、钴、镓、铊等关键金属矿产,具备良好的矿产资源综合利用前景,但矿床中关键金属的分布规律、赋存状态和富集机制等研究尚未开展。本文以武山铜矿床为研究对象,系统采集了矿床南矿带接触带矽卡岩型矿体3条勘探线(W3-2、S4-2、N6-1)、北矿带层控硫化物型矿体3条勘探线(E9-2、E2-1、W4-1)和层控矽卡岩型矿体1条勘探线(E7-3)代表性岩矿石样品。通过光学显微镜和扫描电镜的观察,结合全岩地球化学和矿物原位LA-ICP-MS分析,查明了矿床中硒、碲、钴等关键金属的空间分布规律与赋存状态,初步探讨了硒、碲、钴的迁移沉淀机制。研究结果表明矿床中伴生硒、碲、钴的估算资源量分别为5513t、611t和9597t,均达到大-中型规模;武山矿床是成矿带内硒含量最高、潜在资源量最大的矿床。北矿带矿体中Se、Te、Co含量明显高于南矿带,北矿带中部成矿中心向东西远端,矿体中Se、Te、Co含量规律性增高。矿石中Se、Te、Co含量与S含量具有较强的正相关性,矿石中硫化物的含量是关键金属含量主要控制指标;Se和Co富集于含铜黄铁矿矿石、含铜白云岩矿石、含铜矽卡岩矿石(高硫)中;Te富集于含铜黄铁矿矿石和含铜白云岩矿石中。矿床中硒、碲主要以独立矿物和硫化物中类质同象替换两种赋存形式,钴则主要以Co^(2+)类质同象形式进入黄铁矿矿物晶格。矿床中硒、碲随着成矿流体温度降低、硫逸度升高、氧逸度降低、pH值升高逐渐沉淀富集;钴主要随着硫化物的沉淀富集在黄铁矿中。