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1.
《Chemie der Erde / Geochemistry》2019,79(2):307-322
The Shurab Sb-polymetallic mineralization is a subvolcanic rock-hosted epithermal deposit and located in north Lut Block, eastern Iran. It is one of the most important deposits of the Iranian East Magmatic Assemblage (IEMA) in which numerous Middle-Cenozoic precious and base metals deposits occur. The main lithological units in the area are Paleogene subvolcanic intrusions and minor Jurassic sedimentary rocks. Mineralization occurs as veins in a series of NW-SE and E-W trending faults and fractures in the Eocene-Oligocene dacite and andesite subvolcanic rocks. Mineralization at the Shurab deposit can be subdivided into four stages: pre-ore stage, Cu-Zn-Pb ore stage, Sb-Ag ± As ore stage and post-ore stage. The total sulfide content of the veins in the area is variable, ranging from 1 to 50%, and is dominated by stibnite, chalcopyrite, galena, Fe-poor sphalerite and pyrite with minor chalcostibite, Ag-tetrahedrite and bournonite; gangue minerals are mainly quartz and calcite. Silicic, argillic, propylitic, and sericitic, are the most obvious wall rock alterations. Microthermometric measurements of primary liquid-rich fluid inclusions in quartz and sphalerite indicate that the veins were formed at temperatures between 115 and 290 °C from fluids with salinities between 0.7 and 16.2 wt% NaCl eq., suggesting an epithermal origin. The δ34S values of pyrite, chalcopyrite and galena vary between -2.5 and 0.8‰, and δ18O values of quartz range between 12.5 and 14.8‰. It is inferred that the Shurab mineralization is of epithermal origin, related to an Eocene-Oligocene magmatic geothermal system involving fluids of magmatic and meteoric origin. 相似文献
2.
Sajjad Maghfouri Ebrahim Rastad David R. Lentz Fardin Mousivand Flavien Choulet 《Chemie der Erde / Geochemistry》2018,78(1):40-57
The southwestern Sabzevar basin is the north of Central Iranian Microcontinent hosts abundant mineral deposits, including exhalative Mn mineralization and Cu-Zn volcanogenic massive sulfide (VMS) deposits. Amongst them, the Nudeh Besshi-type Cu–Zn volcanogenic massive sulfide (VMS) deposit is hosted within the lower part of a Late Cretaceous volcano-sedimentary sequence composed of alkali olivine basalt flows and tuffaceous silty sandstone. Based on investigations into the ore geometry, mineralogy, and texture, we recognized three different ore facies: (1) a stockwork of sulfide-bearing quartz veins cutting across the footwall volcano-sedimentary rocks and representing the stringer zone; (2) a massive ore type, displaying replacement texture with pyrite, chalcopyrite, sphalerite, friedrichite, and minor magnetite; and (3) a bedded ore type, with laminated to disseminated pyrite and chalcopyrite. EPMA studies indicate a distinctive minor element distribution between the different ore types of the Nudeh deposit. The Fe content in the sphalerite ranges from 0.65–1.80?wt.%, indicating the Fe-poor nature of the sphalerite. However, the Cd content in sphalerite ranged between 0.164–0.278?wt.%. According to the mineral compositions, Zn, Se, and Ag are found in bornite as minor elements. In the bedded ore facies, the pyrite contains higher levels of Se (up to 0.35?wt.%). The Zn content in the friedrichite in all of the ore samples is low. The Co/Ni ratios in pyrite from the Nudeh ore are lower than those of most magmatic deposits, but are similar to those from volcanogenic deposits, and hence support the proposed hydrothermal origin of the deposit. Two generations of quartz, Q1 and Q2 in the stockwork veins, contain primary fluid inclusions and these contain two phases (liquid and vapor). The lack of vapor-rich inclusions or variable liquid/vapor ratios indicate that the fluids did not boil at the site of trapping. Salinity for both Q1 and Q2 fluid inclusions ranges between 2.2–6.8?wt.% eq. NaCl. Homogenization temperatures for inclusions in the Q1 and Q2 veins average at about 296?°C and are similar to the temperatures of hydrothermal fluids discharged through vents in many modern seafloor VMS deposit. The Nudeh Besshi-type VMS deposit appears to have formed on the seafloor and based on the salinity and temperature constraints from the underlying stockwork, a buoyancy plume model is proposed as a mechanism for precipitation. 相似文献
3.
Abstract: A strange, unidentified, Cu-Fe bearing zinc sulfide occurs in the Laloki massive sulfide deposit, Papua New Guinea. The mineral is optically uniform in texture but is chemically variable and zoned even within a single grain. Copper contents vary from 0.1 up to 8.85 wt%. Iron reaches 18.31 wt% at maximum and decreases as Cu increases. It is remarkable, however, that the total Fe+Cu remains essentially unchanged between roughly 18 and 20 wt%. Zn and S are least variable, giving 45.85–47.84 wt% and 33.48–34.58 wt%, respectively. Other trace elements such as Cd and Mn are in general less than 0.2 wt%. It is strongly suggested that the mineral in question constitutes a unique Fe-Cu substitutional solid solution series belonging essentially to the Zn–Fe–Cu–S system.
The ideal chemical formula of the solid solution series can well be presented as Zn10 (Fe, Cu)5 S15 or Zn2 (Fe, Cu)S3 , where Fe is always greater than Cu. It is intriguing that chalcopyrite blebs are recognizable restrictively only in nearby portions of the Cu-rich end member with the ideal composition close to Zn10 Fe3 Cu2 S15. It has been confirmed by vacuum-sealed heating experiments that this mineral is decomposed to produce chalcopyrite and Fe-bearing normal sphalerite at temperatures below 200C. This would provide another evidence for the existence of such distinct phase as suggested here. 相似文献
The ideal chemical formula of the solid solution series can well be presented as Zn
4.
Ore mineralization and wall rock alteration of Crater Mountain gold deposit, Papua New Guinea, were investigated using ore and host rock samples from drill holes for ore and alteration mineralogical study. The host rocks of the deposit are quartz‐feldspar porphyry, feldspar‐hornblende porphyry, andesitic volcanics and pyroclastics, and basaltic‐andesitic tuff. The main ore minerals are pyrite, sphalerite, galena, chalcopyrite and moderate amounts of tetrahedrite, tennantite, pyrrhotite, bornite and enargite. Small amounts of enargite, tetradymite, altaite, heyrovskyite, bismuthinite, bornite, idaite, cubanite, native gold, CuPbS2, an unidentified Bi‐Te‐S mineral and argentopyrite occur as inclusions mainly in pyrite veins and grains. Native gold occurs significantly in the As‐rich pyrite veins in volcanic units, and coexists with Bi‐Te‐S mineral species and rarely with chalcopyrite and cubanite relics. Four mineralization stages were recognized based on the observations of ore textures. Stage I is characterized by quartz‐sericite‐calcite alteration with trace pyrite and chalcopyrite in the monomict diatreme breccias; Stage II is defined by the crystallization of pyrite and by weak quartz‐chlorite‐sericite‐calcite alteration; Stage III is a major ore formation episode where sulfides deposited as disseminated grains and veins that host native gold, and is divided into three sub‐stages; Stage IV is characterized by predominant carbonitization. Gold mineralization occurred in the sub‐stages 2 and 3 in Stage III. The fS2 is considered to have decreased from ～10?2 to 10?14 atm with decreasing temperature of fluid. 相似文献
5.
Mineral Paragenesis of the Lepanto Copper and Gold and the Victoria Gold Deposits, Mankayan Mineral District, Philippines 总被引：5，自引：0，他引：5
Rene Juna R. CLAVERIA 《Resource Geology》2001,51(2):97-106
Abstract: Mineral paragenesis of the alteration, ore and gangue minerals of the Lepanto epithermal copper‐gold deposit and the Victoria gold deposit, Mankayan Mineral District, Northern Luzon, Philippines, is discussed. The principal ore minerals of the Lepanto copper‐gold deposit are enargite and luzonite, with significant presence of tennantite‐tetrahedrite, chalcopyrite, sphalerite, galena, native gold/electrum and gold‐silver tellurides. Pervasive alteration zonations are commonly observed from silicification outward to advanced argillic then to propylitic zone. The ore mineralogy of the Lepanto copper‐gold deposit suggests high fS2 in the early stages of mineralization corresponding to the deposition of the enargite‐luzonite‐pyrite assemblage. Subsequent decrease in the fS2 formed the chalcopyrite‐tennantite‐pyrite assemblage. An increase in the fS2 of the fluids with the formation of the covellite‐digenite‐telluride assemblage caused the deposition of native gold/electrum and gold‐silver tellurides. The principal ore minerals of the Victoria gold deposit are sphalerite, galena, chalcopyrite, tetrahedrite and native gold/electrum. The alteration halos are relatively narrow and in an outward sequence from the ore, silica alteration grades to illitic‐argillic alteration, which in turn grades to propylitic alteration. The Victoria gold mineralization has undergone early stages of silica supersaturation leading to quartz deposition. Vigorous boiling increased the pH of the fluids that led to the deposition of sulfides and carbonates. The consequent decrease in H2S precipitated the gold. Gypsum and anhydrite mainly occur as overprints that cut the carbonate‐silica stages. The crosscutting and overprinting relationships of the Victoria quartz‐gold‐base metal veins on the Lepanto copper‐gold veins manifest the late introduction of near neutral pH hydrothermal fluids. 相似文献
6.
The metalized quartz veins is located 5 km west of the Iraqi-Iran border in the Qandil range. The quartz veins included sulfide and oxide ore minerals which mostly occur in the form of open-space filling texture. The polymetallic mesothermal quartz veins are hosted by marble and phyllite rocks. Within these veins, multiphase, open-space filling and crustiform, bedding to massive textures with pyrite, sphalerite, galena, chalcopyrite,galena, sphalerite, tenorite, azurite, and malachite are observed. Selected samples were analyzed by using ore microscopy and electron probe micro analyzer (EPMA) and scanning electron microscope (SEM). Ore minerals show replacement textures. The paragenesis diagram was made from a careful study of polished sections and three stages have been identified including pre-stage mineralization, mineralization, and post-mineralization stages.Fluid inclusion microthermometric analysis of 15 primary inclusions of quartz veins indicated that ore mineralization at the studied area were formed by a mesothermal, low to medium density, and dilute NaCl-type fluid system. The source of the fluid is mostly metamorphic which became mixed with other fluids later. Hydrothermal fluids of the selected studied area were classified into two groups based on microthermometry study; the first group had a higher homogenization temperature (335.5 to 386.8 °C) than the second group (194.1 to 298.5 °C), with a small difference in salinity between them. Nearly each group has different complexes including chloride and sulfide complexes respectively. The results of stable sulfur isotope of the ore minerals (chalcopyrite and sphalerite) confirmed the sedimentary and/or metamorphic origin of the ore mineralization. 相似文献
7.
西藏甲玛铜多金属矿床金矿地质特征及成矿作用 总被引：1，自引：0，他引：1
甲玛铜多金属矿床按照赋矿岩石不同,共包含产于矽卡岩中的与铜共生的金矿(化)体、产于板岩-角岩中的脉状金矿(化)体、产于大理岩中的脉状金矿(化)体以及产于玢(斑)岩脉中的独立金矿(化)体4种金矿化类型。矽卡岩中的金矿化较强,全矿区金品位×厚度基本都大于1 m.g/t,存在多个富金块段;板岩中金矿化主要分布在矿区外围破碎细粒黄铁矿化硅化板岩中,角岩中金矿(化)体以富含雄黄、雌黄为特征;大理岩中金矿化较弱,矿(化)体通常呈透镜状产出;玢(斑)岩中金矿化主要产于岩脉中的石英脉内。矿石中金的赋存状态主要以独立矿物和类质同像形式存在。独立矿物形式的金以自然金、银金矿存在于铜矿物、石英、黄铁矿等载金矿物内;类质同像形式的金主要存在于以斑铜矿、黄铜矿为代表的铜矿物中。金矿物赋存状态以粒间金、包裹金为主,其次为连生金和裂隙金。笔者以甲玛铜多金属矿床金的地质特征、分布规律及赋存状态为研究基础,推测甲玛金成矿作用与幔源C-H-O流体有关,并初步建立了甲玛铜多金属矿床金成矿模型。此外,提出了运用模型开展区域及矿区下一步找矿工作的建议。 相似文献
8.
The Pojeonri Cu quartz veins occur in the north-western portion of the Hwanggangri Metallogenic Province and consist of two parallel massive quartz veins that fill fractures oriented NW and NE along fault zones in Paleozoic metasedimentary and sedimentary rocks of the Ogcheon and Taebaeg belts. Based on the mineralogy and paragenesis of the veins, only one mineralization episode has been recognized. The ore minerals are mainly chalcopyrite, pyrrhotite, and pyrite with minor arsenopyrite, sphalerite, galena and oxides of those base metal minerals. 相似文献
9.
Surface water samples from the Drake mining area show elevated metal concentrations, notably cadmium, iron and zinc. A detailed
study of a sphalerite /quartz vein from Strauss Pit and chalcopyrite and pyrite from the Adeline mine and Strauss Pit indicate
that micro-scale analyses of ores are necessary for environmental management of mine sites. Analyses show that Cd is elevated,
up to 2.1 % by weight, and is associated with sphalerite, replacing Zn, or to a lesser extent replacing Pb within small galena
grains. High concentrations of Cu are also associated with the Strauss Pit ore as small chalcopyrite grains along the margins
of the sphalerite vein, within the central quartz zone of the vein system, and as replacement rims on sphalerite grains. Chalcopyrite
from the Adeline mine area, is by comparison, metal poor, but still contains elevated heavy metal concentrations. Whereas,
pyrite and chalcopyrite, from Strauss Pit have variable heavy metal concentrations, with chalcopyrite from within sphalerite
veins having higher Cd and Zn concentrations than chalcopyrite distal to the veins. Cadmium and other heavy metals within
the ores are mobilised during sulphide weathering and enter the drainage network; precipitation of secondary oxidation minerals
act as temporary stores for many heavy metals. The complexity of the mineral and heavy metal associations at Strauss Pit suggest
that a detailed knowledge of these associations and distributions within ore bodies, and associated waste rocks, are needed
by environmental managers of mine sites because the presence of havy metals may greatly affect the decision making process,
and management strategies employed.
Received; 14 July 1999 · Accepted: 17 August 1999 相似文献
10.
The demand in mineral resources is increasing rapidly, but there is a lack of transparency in the trade of concentrated raw mineral materials because of speculation and involvement in the finance of armed conflicts. Because of the distance between primary extraction and the final production sites it is difficult to check the origin of these products. An identity card is required for mineral commodities, so that trading in the industry can be verified and the traceability of concentrates ensured. This problem may be considered as an inversion process: studying the products sold to identify the original ore. The discriminant parameters are mineralogical composition, identification of textural microfacies of the target minerals, “pseudo-paragenetic sequence”, and the contents and distribution of minor elements of target minerals. For base metal, the selected target minerals are pyrite, for its ubiquity, sphalerite for its ability to host numerous discriminant and potentially valuable minor elements in its lattice and chalcopyrite for its proximity with the two other minerals. The Kolmogorov–Smirnov distance and the Colin–White test are used to compare the chemical composition of the three target minerals. The application to Volcanic Massive Sulfide ore deposits shows that it is possible to distinguish pyrite, sphalerite and chalcopyrite between two ore deposits in the Iberian Pyrite Belt province and seven ore deposits from the Urals province using the selected characteristics. Ore deposits from different provinces may be discriminated using the identity cards, as well as different deposits in the same province. 相似文献
11.
Abstract. A detail investigation of ore and gangue minerals was performed on the Doyashiki Kuroko deposits, Hokuroku basin, Japan for the first time. Main ore minerals are sphalerite, galena, pyrite, chalcopyrite, tetrahedrite-tennantite and digen-ite. Small amounts of enargite, wittichenite, electrum, covellite, bornite, marcasite and hematite are also observed. Quartz, barite and gypsum are common gangue minerals. Homogenization temperatures and salinities of fluid inclusions in quartz, sphalerite and barite range from 190 to 240C and 3.0 to 5.5 wt% NaCl equivalent, respectively. The FeS contents of sphalerite and Ag contents of electrum were 0.12 to 0.18 mol %, 39.0 to 39.6 atom %, respectively. The chemical composition of digenite as a primary mineral shows high sulfur contents.
These data indicate that ore fluid responsible for digenite and associated ore minerals was characterized by a range of high sulfur fugacity with a moderate formation temperature. This is concordant with the mineral assemblage of bornite-pyrite and chalcopyrite, which shows high sulfur fugacity conditions. It seems that the mineralization closely associated with acidic volcanism has occurred around 13 Ma of Middle Miocene on the seafloor at the depth of about 1500 m. 相似文献
These data indicate that ore fluid responsible for digenite and associated ore minerals was characterized by a range of high sulfur fugacity with a moderate formation temperature. This is concordant with the mineral assemblage of bornite-pyrite and chalcopyrite, which shows high sulfur fugacity conditions. It seems that the mineralization closely associated with acidic volcanism has occurred around 13 Ma of Middle Miocene on the seafloor at the depth of about 1500 m. 相似文献
12.
13.
Abstract. Intrusion‐related gold deposits are widely distributed within the North China craton or along its marginal fold belts. Presently, about 200 individual intrusion‐related gold deposits (prospects) have been discovered, among which Yuerya, Anjia‐yingzi, Linglong, Jiaojia, Chenjiazhangzi, Qiyugou, Jinjiazhuang, Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang are the most important ones. In general, the intrusion‐related gold deposits can be classified into three major groups according to their host rocks: (1) hosted by or related to felsic intrusions, including (la) calc‐alkaline granitoid intrusions and (lb) cryptoexplosion breccia pipes; (2) related to ultramafic intrusions, and (3) hosted by or related to alkaline intrusions. The first group contains the Yuerya, Anjiayingzi, Linglong, Jiaojia, Chenjiazhangzi and Qiyugou gold deposits. Gold mineralization at these deposits occurs within Mesozoic Yanshanian calc‐alkaline granitoid intrusions or cryptoexplosion breccia pipes as gold‐bearing quartz veins and replacement bodies. Pyrite, galena, sphalerite, chalcopyrite, native gold and electrum are major metallic minerals. The Jinjiazhuang deposit belongs to the second group, and occurs within Hercynian diopsidite and peridotite as quartz veins and replacement bodies. Pyrite, marcasite, arsenopyrite, native gold and electrum are identified. The third group includes the Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang deposits. Gold mineralization at these deposits occurs predominantly within the Hercynian alkaline intrusive complexes as K‐feldspar‐quartz veins and replacement bodies. Major metal minerals are pyrite, galena, chalcopyrite, tellurides, native gold and electrum. All these pyrite separates from Hercynian and Yanshanian intrusions or cryptoexplosion pipes associated with the gold deposits show a broad range in δ34S value, which is overall higher than those Precambrian rocks and their hosted gold deposits. For the alkaline intrusion‐related gold deposits, the δ34S values of the sulfides (pyrite, galena and chalcopyrite) from the deposits increase systematically from orebodies to the alkaline intrusions. All of these intrusion‐related gold deposits show relatively radiogenic lead isotopic compositions compared to mantle or lower crust curves. Most lead isotope data of sulfides from the gold ores plot in between the fields of the intrusions and Precambrian metamorphic rocks. Data are interpreted as indicative of a mixing of sulfur and lead from magma with those from Precambrian metamorphic rocks. Isotopic age data, geological and geochemical evidences suggest that the ore‐forming materials for the intrusion‐related gold deposits were generated during the emplacement of the Hercynian or Yanshanian intrusion. The calc‐alkaline or alkaline magma may provide heat, volatiles and metals for the intrusion‐related gold deposits. Evolved meteoric water, which circulated the wall rocks, was also progressively involved in the magmatic hydrothermal system, and may have dominated the ore fluids during late stage of ore‐forming processes. Therefore, the ore fluid may have resulted from the mixing of calc‐alkaline or alkaline magmatic fluids and evolved meteoric water. All these intrusion‐related gold deposits are believed to be products of Hercynian or Yanshanian calc‐alkaline and alkaline igneous processes along deep‐seated fault zones within the North China craton or along its marginal belts. 相似文献
14.
英城子金矿床位于兴蒙造山带东缘,矿床产于近东西向韧性脆性剪切带（靡棱岩带）内,矿体主要呈透镜状、似层状和脉状产出.矿石矿物主要为黄铁矿、闪锌矿和黄铜矿,主要结构为交代结构、乳滴状结构、半自形-他形结构,主要构造为浸染状构造、脉状构造、条带状构造.成矿作用先后经历了4个阶段：石英-毒砂-黄铁矿阶段、石英-黄铁矿阶段、石英-多金属硫化物阶段和石英-方解石阶段.成矿流体总体属于中温、低盐度、低密度的CO2-CH4-H2O体系.英城子金矿床与国内外典型的造山型金矿相比具有诸多相似之处,其成因类型属于造山型金矿. 相似文献
15.
The Ohori deposit, one of the base metal deposits in the Green-Tuff region, NE Japan, is composed of two types of mineralization; a skarn-type (Kaninomata orebody) made by the replacement of the Miocene calcareous layer, and a vein-type (Nakanomata orebody). While the ore mineral assemblage of the deposit (chalcopyrite, pyrite, sphalerite and galena) has been known for being rather simple, some Pb-Bi-S minerals have been discovered for the first time in the present study. The minerals mainly occur in the chalcopyrite-rich ores of both orebodies. They essentially belong to the Pb-Bi-S system and contain Cu and Ag in minor amounts, which correspond to the lillianite–gustavite solid solution series (phases Z and X), cosalite, neyite, felbertalite, krupkaite and Bi-bearing galena. The chalcopyrite-rich (Bi-bearing) ores from both orebodies are richer in chalcopyrite, pyrite and chlorite, and have higher homogenization temperatures (>300°C) of fluid inclusions, and higher FeS contents in sphalerite compared to the Bi-free ores. In the Green-Tuff region, Bi-minerals have been reported from many base metal deposits. Most of these Bi-bearing ore deposits are referred to as xenothermal-type deposits, and are characterized by the following common features; composite mineralization of high- and low-temperatures in the shallower environments, and close relationships with the Tertiary granitic rocks. The whole mineralization at the Ohori deposit also has a similar xenothermal character because of the coexistence of high-temperature chalcopyrite-rich ores with Pb-Bi-S minerals, which were formed by the influence of the Tertiary granitic rocks at a shallow depth. 相似文献
16.
为查清安徽金寨迎峰崖含金银富铅锌多金属矿矿区内矿石的物质组分及矿物嵌布特征,采用化学多元素分析、光片和薄片镜下鉴定、X射线衍射分析以及单矿物组分分析等方法,对矿石的物质组分、矿物的嵌布特征进行分析测试。结果表明,矿石中主要矿物为方铅矿、闪锌矿、黄铜矿、黄铁矿、石英等。方铅矿、闪锌矿以包裹嵌镶或黏连镶布为主,细小的方铅矿与其他矿物毗邻,交代成因的闪锌矿呈融滴状分布于被交代矿物之上。Au充填于黄铁矿晶隙中;Ag在方铅矿中富集,主要以化合物形式存在;闪锌矿中有害组分Cd（2 697 mg/kg）严重超标,其他有害组分为Fe、S、As等。矿石矿物颗粒粒度以中粗粒为主。研究结果可为矿物分离及后期的开发利用提供参考。 相似文献
17.
Abstract. The Meng'entaolegai In-rich Ag-Pb-Zn deposit is located in the eastern part of Inner Mongolia. It is one of the In-richest deposits in China. Large amounts of quartz and sulfide minerals constitute a hydrothermal quartz-sulfide vein deposit within a Hercynian acidic granite massif, which occupies an area of about 400 km2 . Thirty-six orebodies, controlled strictly by the E-W trend faults, are found in the orefield of 6 km in length from east to west and 200 to 1,000 m in width from south to north. The ore minerals are mainly galena, sphalerite and pyrite, and subordinate chalcopyrite, arsenopyrite, cassiterite and stannite with many Ag-minerals. The gangue minerals are mainly quartz, calcite, sericite and chlorite. Economic components of the deposit are dominated by Pb andZn (reserves of Pb and Zn are 0.17 Mt and 0.37 Mt, and their grades are 1 % and 2.3 %, respectively), with Ag, Sn, In and Cd (1,800 t Ag, >2,000 t Sn, >500 t In and 1,800 t Cd) as by-products. Indium is highly enriched in ores and its contents are 9 to 295 ppm in ores and 85 to 2,660 ppm in sphalerite. Analytical results show that the ore-forming fluid of this deposit contains 0.8–3.5 ppm In and 4–36 ppm Sn, and the two elements show a very good positive correlation with a correlation coefficient of 0.8672, while the correlation between In and Zn in the ore-forming fluids, with a correlation coefficient of 0.5723, is not as good as that between In and Sn. This indicates that indium has an affinity with tin in the ore-forming fluids. The authors think that this is probably the main reason why those In-rich deposits spread over the world are simultaneously enriched in tin. 相似文献
18.
《International Geology Review》2012,54(14):1635-1648
The Koushk zinc–lead deposit in the central part of the Zarigan–Chahmir basin, central Iran, is the largest of several sedimentary–exhalative (SEDEX) deposits in this basin, including the Chahmir, Zarigan, and Darreh-Dehu deposits. The host-rock sequence consists of carbonaceous, fine-grained black siltstone with interlayered rhyolitic tuffs. It corresponds to the upper part of the Lower Cambrian volcano-sedimentary sequence that was deposited on the Posht-e-Badam Block due to back-arc rifting of the continental margin of the Central Iranian Microcontinent. This block includes the late Neoproterozoic metamorphic basement of the Iran plate, overlain by rocks dating from the Early Cambrian to the Mesozoic. Based on ore body structure, mineralogy, and ore fabric, we recognize four different ore facies in the Koushk deposit: (1) a stockwork/feeder zone, consisting of a discordant mineralization of sulphides forming a stockwork of sulphide-bearing dolomite (quartz) veins cutting the footwall sedimentary rocks; (2) a massive ore/vent complex, consisting of massive replacement pyrite, galena, and sphalerite with minor arsenopyrite and chalcopyrite; (3) bedded ore, with laminated to disseminated pyrite, sphalerite, and galena; and (4) a distal facies, with minor disseminated and laminated pyrite, banded cherts, and disseminated barite. Carbonatization and sericitization are the main wall-rock alterations; alteration intensity increases towards the feeder zone. The δ34S composition of pyrite, sphalerite, and galena ranges from?+6.5 to?+36.7‰. The highest δ34S values correspond to bedded ore (+23.8 to?+36.7‰) and the lowest to massive ore (+6.5 to?+?17.8‰). The overall range of δ34S is remarkably higher than typical magmatic values, suggesting that sulphides formed from the reduction of seawater sulphate by bacteriogenic sulphate reduction in a closed or semi-closed system in the bedded ore, whereas thermochemical sulphate reduction likely played an important role in the feeder zone. Sulphur isotopes, along with sedimentological, textural, mineralogical, and geochemical evidences, suggest that this deposit should be classified as a vent-proximal SEDEX ore deposit. 相似文献
19.
栖霞山铅锌矿位于长江中下游成矿带东部,是我国东部最大的铅锌矿床。通过矿区接替资源勘查,在深部取得重大突破,主矿体控制深度由-650 m延深至-1 079 m,且在深部发现了绿帘石、透闪石、透辉石等矽卡岩蚀变矿物。结合最新成果,从控矿地质因素、矿体地质、成矿元素的空间分带特征等入手,全面总结了矿床地质特征。通过分析黄铁矿、闪锌矿、方铅矿、黄铜矿中S同位素组成,发现黄铁矿中的硫来源于沉积岩和岩浆,而闪锌矿、方铅矿和黄铜矿中的硫来源于岩浆;硫化物中Pb同位素的分布特征指示矿石铅主要来源于上地壳与地幔混合;碳酸盐矿物C、O同位素组成反映成矿流体与岩浆热液的亲缘关系;H、O同位素特征反映成矿流体主要为深部岩浆期后热液,并有大气水的加入。综合地质与同位素地球化学研究成果,对栖霞山铅锌矿床的成因进行了探讨。 相似文献
20.
《International Geology Review》2012,54(1):116-129
The Arapuçandere Pb–Zn–Cu ore body is a typical vein-type lead–zinc deposit of the Biga Peninsula, and is currently being mined for lead and zinc. In the study area, Permian–Triassic metamorphic rocks, Triassic metaclastic and metabasic rocks, Oligocene–Miocene granitoids, Miocene volcanic rocks, and Quaternary terrigenous sediments crop out. The ore deposits developed as Pb–Zn–Cu-bearing veins along faults in Triassic metasandstone and metadiabase. Microscopic studies reveal that the veins contain galena, sphalerite, chalcopyrite, pyrite, marcasite, covellite, and specular hematite as ore minerals, and quartz, calcite, and barite as gangue minerals. Analysed sulphur-isotope compositions (δ34SVCDT) of galena, sphalerite, and chalcopyrite range from ? 5.9 to ? 1.9‰ (average ? 3.4‰), from ? 5.5 to ? 1.7‰ (average ? 4.2 ‰), and from ? 3.5 to ? 0.9‰ (average ? 2.6‰), respectively; that of H2S in the hydrothermal fluid was in the calculated range of ? 5.8 to +0.1‰ (average ? 2.5‰). These isotopic values suggest that magmatic sulphur dominates in sulphides, mixed with minor, isotopically light sulphur. Because no contemporaneous magmatic activity is associated with mineralization, it may be assumed that sulphur was leached from the surrounding Triassic units, mainly from metabasic, partly from metaclastic rocks. Lead-isotope studies indicate a model age of 114–63 Ma for the lead reservoir, in accord with possible sulphur-bearing local source rocks. Thus, the sulphur and lead deposited in the studied ore veins were probably leached from Triassic metabasic and metaclastic rocks some time during the Early Cretaceous to the Palaeocene. 相似文献