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1.
Barite (BaSO4) deposits generally arise from mixing of soluble barium-containing fluids with sulfate-rich fluids. While the role of biological processes in modulating barium solubility has been shown, no studies have shown that the biological oxidation of sulfide to sulfate leads to barite deposition. Here we present an example of microbially mediated barite deposition in a continental setting. A spring in the Anadarko Basin of southwestern Oklahoma produces water containing abundant barium and sulfide. As emergent water travels down a stream to a nearby creek, sulfate concentration increases from 0.06 mM to 2.2 mM while Ba2+ concentration drops from 0.4 mM to less than 7 μM. Stable isotope analysis, microbial activity studies, and in situ experiments provide evidence that as sulfide-rich water flows down the stream, anaerobic, anoxygenic, phototrophic bacteria play a dominant role in oxidizing sulfide to sulfate. Sulfate then precipitates with Ba2+ producing barite as travertine, cements, crusts, and accumulations on microbial mats. Our studies suggest that phototrophic sulfide oxidation and concomitant sulfur cycling could prove to be important processes regulating the cycling of barium in continental sulfur-containing systems.  相似文献   

2.
During the production of hydrocarbons from subterranean reservoirs, scaling with calcium carbonate and barium sulfate causes flux decline and dangerous problems in production facilities. This work is intended to study the effect of calcium ions on the precipitation of barium sulfate (barite); then, the effect of the formed barite on calcium carbonate crystallization. The conductometric and pH methods were used to follow the progress of the precipitation reaction in aqueous medium. The obtained precipitates were characterized by FTIR, RAMAN, SEM, and XRD. It was shown that Ca2+ in the reaction media does not affect the microstructure of barite even for higher calcium–barium molar ratio. It influences the precipitation kinetics and the solubility of barite by the formation of CaSO4° ion pairing as a predominant role of complex formation (CaSO4) and the increase of the ionic strength. In Ca(HCO3)2-BaSO4-NaCl aqueous system, experiments have showed that added or formed barite in the reaction media accelerates calcite precipitation. No effect on the microstructure of heterogeneous formed calcite which remain calcite shape. However the presence of carbonate ions affects slightly the microstructure of barite.  相似文献   

3.
The precipitation of extremely 34S-rich barite in the late stage of mineralization in the Mississippi Valleytype deposits of the Illinois-Kentucky district (U.S.A.) may be explained by reactions involving thiosulfate (S2O 3 = ). Inorganic processes are known to concentrate 34S in the sulfonate site of thiosulfate and 32S in the sulfate site. In the mineralizing solution, these inorganic processes may have fractionated sulfur between the two sites by about 40 per mil. At the low temperatures of the late barite stage of mineralization, bacteria are known to metabolize thiosulfate by various reactions. In one of these, dissimilatory reduction, hydrogen sulfide and sulfite are produced. Isotopically light sulfite is preferentially reduced to sulfide by bacteria to leave a residual sulfite enriched in 34S. Part of the residual sulfite may be oxidized to form isotopically heavy sulfate; part may recombine with hydrogen sulfide to form thiosulfate. The recombination also enriches the sulfonate site in 34S and the sulfane site in 32S. Recycling the newly formed thiosulfate through the above steps further enriches sulfite and sulfate from oxidation of sulfite in 34S. During genesis of the ores, the aggregate effect of these reactions may have been the precipitation of extremely 34S-rich barite. The sequence of reactions suggested above requires the presence of organic matter. Previously proposed reactions to account for the precipitation of sulfide minerals and fluorite and for the carbonate paragenesis also require the presence of organic matter. Thus, organic matter in the host rocks may cause the various ore-zone reactions and account for the localization of the ores.  相似文献   

4.
Sulfur- and oxygen-isotopes in sediment-hosted stratiform barite deposits   总被引：2，自引：0，他引：2  
Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for other localities are considered, sulfur- and oxygen-isotope data are now available for deposits spanning a host-rock age range of Late Neoproterozoic to Triassic. On a δ34S versus δ18O diagram, many deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trends suggest that barite formed from seawater sulfate that had been isotopically modified to varying degrees. The δ34S versus δ18O patterns resemble patterns that have been observed in the modern oceans in pore water sulfate and water column sulfate in some anoxic basins. However, the closest isotopic analog is barite mineralization that occurs at fluid seeps on modern continental margins. Thus the data favor genetic models for the deposits in which barium was delivered by seafloor seeps over models in which barium was delivered by sedimentation of pelagic organisms. The isotopic variations within the deposits appear to reflect bacterial sulfate reduction operating at different rates and possibly with different electron donors, oxygen isotope exchange between reduction intermediates and H2O, and sulfate availability. Because they are isotopically heterogeneous, sediment-hosted stratiform barite deposits are of limited value in reconstructing the isotopic composition of ancient seawater sulfate.  相似文献   

5.
Sulfate-reducing bacteria (SRB) are ubiquitous in anoxic environments where they couple the oxidation of organic compounds to the production of hydrogen sulfide. This can be problematic for various industries including oil production where reservoir “souring” (the generation of H2S) requires corrective actions. Nitrate or nitrite injection into sour oil fields can promote SRB control by stimulating organotrophic nitrate- or nitrite-reducing bacteria (O-NRB) that out-compete SRB for electron donors (biocompetitive exclusion), and/or by lithotrophic nitrate- or nitrite-reducing sulfide oxidizing bacteria (NR-SOB) that remove H2S directly. Sulfur and oxygen isotope ratios of sulfide and sulfate were monitored in batch cultures and sulfidic bioreactors to evaluate mitigation of SRB activities by nitrate or nitrite injection. Sulfate reduction in batch cultures of Desulfovibrio sp. strain Lac15 indicated typical Rayleigh-type fractionation of sulfur isotopes during bacterial sulfate reduction (BSR) with lactate, whereas oxygen isotope ratios in unreacted sulfate remained constant. Sulfur isotope fractionation in batch cultures of the NR-SOB Thiomicrospira sp. strain CVO was minimal during the oxidation of sulfide to sulfate, which had δ18OSO4 values similar to that of the water-oxygen. Treating an up-flow bioreactor with increasing doses of nitrate to eliminate sulfide resulted in changes in sulfur isotope ratios of sulfate and sulfide but very little variation in oxygen isotope ratios of sulfate. These observations were similar to results obtained from SRB-only, but different from those of NR-SOB-only pure culture control experiments. This suggests that biocompetitive exclusion of SRB took place in the nitrate-injected bioreactor. In two replicate bioreactors treated with nitrite, less pronounced sulfur isotope fractionation and a slight decrease in δ18OSO4 were observed. This indicated that NR-SOB played a minor role during dosing with low nitrite and that biocompetitive exclusion was the major process. The results demonstrate that stable isotope data can contribute unique information for understanding complex microbial processes in nitrate- and sulfate-reducing systems, and offer important information for the management of H2S problems in oil reservoirs and elsewhere.  相似文献   

6.
A unique occurrence of strontian barite droplets associated with oriented planes of primary sulfide blebs in several clinopyroxene megacrysts was found in the Plio-Pleistocene basaltic tuff of Szentbékkálla (Bakony–Balaton Highland, western Hungary). The barite droplets contain 3.22–14.7 wt.% SrO, variable amount of FeO (up to 3.25 wt.%), minor CaO, CuO and NiO. Textural arrangements of oriented sulfide planes show that they were trapped as immiscible sulfide melt during crystallization of the clinopyroxene. Temperature and pressure estimation (978–1094 °C and 1.0–1.1 GPa) of the host clinopyroxenes indicate that formation of clinopyroxene megacrysts and entrapment of sulfide blebs happened under upper mantle conditions.

A genetic relationship between the sulfate and sulfide blebs is doubtful. Textural features suggest that the barite droplets might have been trapped together with the sulfide blebs from immiscible sulfide melts. However, it cannot be excluded that the barite formed during metasomatic event following the sulfide formation.  相似文献   


7.
海洋天然气水合物系统硫同位素研究进展   总被引：2，自引：2，他引：0  
在海洋天然气水合物的地质系统中,甲烷的渗漏作用形成了独特的地球化学微环境。渗漏的甲烷在硫酸根-甲烷氧化还原界面与硫酸根之间发生厌氧氧化反应,同时硫酸盐发生还原反应,形成具有特殊同位素组成的自生碳酸盐、硫化物（AVS、黄铁矿等）和硫酸盐（重晶石、石膏）等。反应过程中硫酸盐还原菌的作用使得产物中硫的同位素发生了强烈分馏,具体表现为低δ34S值的硫化物矿物和高δ34S值的硫酸盐矿物的形成。沉积物中这种独特的硫同位素特征与海洋天然气水合物系统中独特地球化学微环境有关,是硫酸盐还原反应过程中细菌控制的硫酸盐分馏和厌氧细菌对硫的歧化反应（disproportionation）的共同作用结果。  相似文献   

8.
The distribution of mineral deposits, characterised as barite deposits, hematite-rich auriferous deposits and auriferous tourmaline–sulfide deposits, displays a regional sulfate–hematite–sulfide zoning along the thrust-delineated limbs of the Mariana anticline, in the south-eastern part of the Quadrilátero Ferrífero of Minas Gerais, Brazil. Cross-cut relationships of barite veins and sulfide lodes indicate that sulfidation occurred in a late-tectonic context, which is here attributed to the collapse of the ～0.6-Ga Brasiliano thrust front. Reconnaissance S-isotopic data from barite and pyrite (Antônio Pereira barite deposit and its adjacent gold deposit, respectively), and arsenopyrite (Passagem de Mariana gold deposit), suggest a new interpretation for the hydrothermal fluid overprint in the Mariana anticline. The Antônio Pereira barite has Δ33S values that are near zero, constraining the sulfate source to rocks younger than 2.45 Ga. The barite-δ34S values are between +19.6 and +20.8?‰. The Passagem arsenopyrite and tourmaline have Co/Ni ratios that define a positive linear trend with the Antônio Pereira pyrite. The latter has homogenous δ34S values, between +8.8 and +8.9?‰, which are compatible with thermochemical reduction of aqueous sulfate with the S-isotopic composition of the Antônio Pereira barite.  相似文献   

9.
The Kuzha barite-base-metal deposit is located on the western slope of the southern Urals and is hosted in strongly deformed Riphean rocks. The Main barite zone is related to a tectonic suture accompanied by alkaline and basic dikes. The stratiform base-metal ore mineralization is confined to a dolomite layer conjugated with the suture zone. The ore mineralization was formed as a result of interaction between heated mineralized water ascending along the suture zone and descending sulfate-bearing vadose water. Biogenic sulfate reduction played the main role in sulfide precipitation. The heating of the ore-forming medium up to 120°C terminated sulfate reduction and facilitated deposition of barite. The Kuzha deposit has much in common with other base-metal and barite-base-metal deposits in Russia, Kazakhstan, and the United States.  相似文献   

10.
《Applied Geochemistry》2000,15(2):235-243
Sulfide mineral weathering is a major source of acid generation in mining environments. Oxidation and hydrolysis reactions in soil and geologic material under earth surface conditions causes weathering of reduced sulfide minerals resulting in liberation of weathering products including acid. Pyrite and marcasite are minerals common in mine environments that cause acid generation. Many other sulfide minerals are present in mining environments which may or may not form acid upon weathering. Characterization of complex mineral assemblages containing S compounds is therefore critically important to pre-mine planning and postmine waste characterization. Despite the importance of mineral weathering behavior, little is known about the acid generation characteristics of common sulfide and sulfate minerals. To assess the response of common sulfide and sulfate minerals to oxidizing conditions, 13 minerals were subjected to treatment with 10% H2O2. The resulting leachate was analyzed for pH, electrical conductivity, S and titratable acidity. The sulfide minerals arsenopyrite, pyrite, chalcopyrite, pyrrhotite, marcasite and sphalerite demonstrated significantly elevated levels of titratable acidity and are acid generating in contrast to galena, chalcocite and all the sulfates. The sulfate minerals barite, anhydrite, gypsum, anglesite and jarosite were included in experimentation and were found not to form acid under strongly oxidizing conditions. Remediation strategies for disturbed lands containing reduced S minerals must therefore consider not only the total quantity of sulfide minerals present, but the specific mineralogy of the S compounds.  相似文献   

11.
The effect of dissolved barium on biogeochemical processes at cold seeps   总被引：2，自引：0，他引：2  
A numerical model was applied to investigate and quantify the biogeochemical processes fueled by the expulsion of barium and methane-rich fluids in the sediments of a giant cold-seep area in the Derugin Basin (Sea of Okhotsk). Geochemical profiles of dissolved Ba2+, Sr2+, Ca2+, SO42−, HS−, DIC, I− and of calcium carbonate (CaCO3) were fitted numerically to constrain the transport processes and the kinetics of biogeochemical reactions. The model results indicate that the anaerobic oxidation of methane (AOM) is the major process proceeding at a depth-integrated rate of 4.9 μmol cm−2 a−1, followed by calcium carbonate and strontian barite precipitation/dissolution processes having a total depth-integrated rate of 2.1 μmol cm−2 a−1. At the low seepage rate prevailing at our study site (0.14 cm a−1) all of the rising barium is consumed by precipitation of barite in the sedimentary column and no benthic barium flux is produced. Numerical experiments were run to investigate the response of this diagenetic environment to variations of hydrological and biogeochemical conditions. Our results show that relatively low rates of fluid flow (<∼5 cm a−1) promote the dispersed precipitation of up to 26 wt% of barite and calcium carbonate throughout the uppermost few meters of the sedimentary column. Distinct and persistent events (several hundreds of years long) of more vigorous fluid flow (from 20-110 cm a−1), instead, result in the formation of barite-carbonate crusts near the sediment surface. Competition between barium and methane for sulfate controls the mineralogy of these sediment precipitates such that at low dissolved methane/barium ratios (<4-11) barite precipitation dominates, while at higher methane/barium ratios sulfate availability is limited by AOM and calcium carbonate prevails. When seepage rates exceed 110 cm a−1, barite precipitation occurs at the seafloor and is so rapid that barite chimneys form in the water column. In the Derugin Basin, spectacular barite constructions up to 20 m high, which cover an area of roughly 22 km2 and contain in excess of 5 million tons of barite, are built through this process. In these conditions, our model calculates a flux of barium to the water column of at least 20 μmol cm−2 a−1. We estimate that a minimum of 0.44 × 106 mol a−1 are added to the bottom waters of the Derugin Basin by cold seep processes, likely affecting the barium cycle in the Sea of Okhotsk.  相似文献   

12.
The Draïssa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draïssa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting.  相似文献   

13.
《Applied Geochemistry》1994,9(5):561-567
The inhibition of gypsum and barite nucleation in NaCl brines by phosphonates and polycarboxylates was studied at 25, 50, 70 and 90°C in terms of the prolonged induction period. Hexamethylene-diaminetetra (methylene phosphonic) acid (HDTMP) was found to be an effective inhibitor for the scaling of calcium sulfate dihydrate. Hydroxyethylene-1, 1-diphosphonic acid (HEDP) and phosphinopolycarboxylic acid (PPPC) were found to be effective inhibitors for barium sulfate scaling. The inhibition of nucleation through prolongation of the nucleation induction period likely resulted from an increase in the interfacial tension between the crystal and aqueous solution due to the presence of the inhibitors. It was observed that the inhibition of nucleation depends highly on the lattice cation/anion molar ratio and the pH of the solution as well as the degree of supersaturation and temperature for a given inhibitor.  相似文献   

14.
Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2–3 ‰ heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.  相似文献   

15.
冲绳海槽Jade热液活动区热液沉积物主要以块状硫化物和硫酸盐矿物为主。与其它热液活动区相比,本区的热液沉积物以富含Pb和Ag等元素为特征。电子探针和中子活化的分析结果表明,在块状硫化物矿石中,Ag主要以分散态富集在粗粒硫化物和细粒硫化物集合体中,在热液活动的早期和晚期均有Ag的富集。在以硬石膏为主的块状矿石中,Ag主要在细粒硫化物集合体中富集,其富集成矿的时间为热液活动的中后期,富集成矿温度在150℃以上。在重晶石为主的块状矿石中,Ag主要以颗粒状自然银的形式在热液活动后期富集成矿,其成矿温度低于160℃。  相似文献   

16.
钡以BaSO_4形式存在的重晶石矿床在世界上广泛分布,但以BaCO_3形式存在的毒重石矿床极为罕见。在南秦岭早古生代硅岩建造中,发育大量层状毒重石和重晶石矿床,两类矿床在空间上表现出既共生又分离的分布规律,构成世界上极为独特的大型钡成矿带。本文对毒重石、钡解石、重晶石及石英等矿物流体包裹体进行了系统研究,结果显示,各矿物中流体包裹体的均一温度都变化于90～310℃,主要集中范围为120～220℃。尽管如此,毒重石、钡解石的形成温度峰值比重晶石高出40℃,而石英的形成温度分布较均一,没有出现明显的峰值。矿物流体包裹体的盐度虽变化于1%～15%NaCl_(eqv),但毒重石、钡解石和石英样品中的盐度值普遍大于5%NaCl_(eqv),而重晶石中的盐度值小于5%NaCl_(eqv)的样品数量占有相当大的比例。由于重晶石的流体包裹体主要以NaCl-H_2O型包裹体为主,而毒重石中富含大量N_2-CO_2-H_2S-CH_4等复杂组分水溶液型包裹体,显示出毒重石与重晶石在成矿环境上有较大差异。由此笔者明确提出,水溶液热化学硫酸盐还原作用是形成毒重石矿床主要机制的新认识。  相似文献   

17.
高频红外碳硫仪测定重晶石和黄铁矿中的硫   总被引：2，自引：2，他引：0  
硫酸盐矿石和硫化物矿石大部分是低电磁性的物质,利用高频红外碳硫仪测定这类矿石中的硫时,在燃烧过程中难以产生较大的电磁感应涡流,导致矿石中的硫释放不完全,造成硫的测定结果偏低。本文采用二氧化硅将重晶石精矿和黄铁矿精矿稀释成不同硫含量的重晶石和黄铁矿样品,通过优化称样量及助熔剂等测试条件,建立了使用高频红外碳硫仪测定重晶石和黄铁矿中硫含量的分析方法。结果表明:当样品中的硫含量高于2%时确定称样量为0.07 g,当硫含量低于2%时确定称样量为0.1 g,加入助熔剂0.4 g锡粒+0.4 g铁粒+1.5 g钨粒,可使重晶石和黄铁矿中的硫完全释放进入仪器红外吸收区域,硫的回收率提高至95.8%~104.2%(重晶石)和95.3%~105.1%(黄铁矿),分别高于常规红外碳硫仪的回收率(83.39%~91.1%和91.5~97.5%)。本方法精密度高(RSD5%),实现了硫含量的准确测定。  相似文献   

18.
We have used a new thermodynamic model of barium and calcium sulfate solubilities in multicomponent electrolyte solutions (Monnin, 1999) to investigate the stabilities of barite and anhydrite in seawater or in marine sediment porewaters at high temperature and pressure. As a further test supplementing those previously carried out during model development, we have calculated the temperature at which standard seawater becomes saturated with respect to anhydrite. The model predicts that, upon heating at 500 bars, standard seawater becomes saturated with respect to anhydrite at 147 ± 5°C, which compares well with the literature value of 150°C (Bishoff and Seyfried, 1978). At 20 bars the calculated saturation temperature is 117 ± 3°C. This points to a non negligible pressure effect even at moderate pressures.We have calculated the barite and anhydrite saturation indices for the in situ temperatures and pressures, from the composition of porewaters collected at ODP Sites 855, 856, 857, 858, 1035 and 1036 during ODP Legs 139 and 169 (Juan de Fuca and Gorda ridges, NE Pacific). Calculated saturation indices for porewater samples collected at depths corresponding to temperatures between 70° and 110-120°C at an in situ pressure of about 260 bars yield equilibrium values for anhydrite and barite. Saturation indices of samples collected at depths where the temperature exceeds 110-120°C, however, yield values indicating supersaturation with respect to anhydrite and undersaturation with respect to barite. This result is consistent with the redissolution of anhydrite during cooling, leading to the well documented sampling artifact affecting porewater compositions in high temperature marine sediments: anhydrite dissolution increases the porewater sulfate content, which in turn induces a loss of barium from solution through barite precipitation (the common ion effect). We postulate that this redissolution occurs in sediment samples for which the in situ temperature exceeds 110-120°C: below this limit anhydrite remains at equilibrium or does not have time to significantly dissolve before porewaters are sampled.  相似文献   

19.
Two strains of moderately halophilic bacteria were grown in aerobic culture experiments containing gel medium to determine the Sr partition coefficient between dolomite and the medium from which it precipitates at 15 to 45 °C. The results demonstrate that Sr incorporation in dolomite does occur not by the substitution of Ca, but rather by Mg. They also suggest that Sr partitioning between the culture medium and the minerals is better described by the Nernst equation (DSrdol = Srdol/Srbmi), instead of the Henderson and Kracek equation (DSrdol = (Sr/Ca)dol/(Sr/Ca)solution. The maximum value for DSrdol occurs at 15 °C in cultures with and without sulfate, while the minimum values occur at 35 °C, where the bacteria exhibit optimal growth. For experiments at 25, 35 and 45 °C, we observed that DSrdol values are greater in cultures with sulfate than in cultures without sulfate, whereas DSrdol values are smaller in cultures with sulfate than in cultures without sulfate at 15 °C.Together, our observations suggest that DSrdol is apparently related to microbial activity, temperature and sulfate concentration, regardless of the convention used to assess the DSrdol. These results have implications for the interpretation of depositional environments of ancient dolomite. The results of our culture experiments show that higher Sr concentrations in ancient dolomite could reflect microbial mediated primary precipitation. In contrast, previous interpretations concluded that high Sr concentrations in ancient dolomites are an indication of secondary replacement of aragonite, which incorporates high Sr concentrations in its crystal lattice, reflecting a diagenetic process.  相似文献   

20.
大河边重晶石矿床是一个世界级的超大型重晶石矿床。最近在该区重晶石矿床下部的震旦系陡山沱组碳酸盐岩(白云岩)和碎屑岩中,新发现一套规模较大、层位产出稳定的铅锌矿化。铅锌矿体和重晶石矿床具有"上部为重晶矿,下部为铅锌硫化物矿床"的矿化特征。铅锌矿段矿石矿物主要为闪锌矿、黄铁矿及方铅矿,含少量白铁矿、黄铜矿及磁黄铁矿;脉石矿物主要为石英和重晶石,少量白云石、热液磷灰石、炭沥青及钡冰长石。成矿流体特征类似于形成沉积喷流型铅锌矿床的流体特征。铅锌矿化中的硫源自局限海盆内早寒武世海水经硫酸盐还原作用提供。此种类似于喷流沉积型铅锌矿床在南华裂谷盆地一带矿化层位稳定、分布范围较广泛,体现早寒武世时在裂谷盆地内存在一次大规模的热液事件。天柱大河边铅锌矿床的发现具有重要的资源意义及区内该种矿床的勘查意义。  相似文献   

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