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1.
《Ore Geology Reviews》2003,22(1-2):61-90
Quantitative laser ablation (LA)-ICP-MS analyses of fluid inclusions, trace element chemistry of sulfides, stable isotope (S), and Pb isotopes have been used to discriminate the formation of two contrasting mineralization styles and to evaluate the origin of the Cu and Au at Mt Morgan.The Mt Morgan Au–Cu deposit is hosted by Devonian felsic volcanic rocks that have been intruded by multiple phases of the Mt Morgan Tonalite, a low-K, low-Al2O3 tonalite–trondhjemite–dacite (TTD) complex. An early, barren massive sulfide mineralization with stringer veins is conforming to VHMS sub-seafloor replacement processes, whereas the high-grade Au–Cu ore is associated with a later quartz–chalcopyrite–pyrite stockwork mineralization that is related to intrusive phases of the Tonalite complex. LA-ICP-MS fluid inclusion analyses reveal high As (avg. 8850 ppm) and Sb (avg. 140 ppm) for the Au–Cu mineralization and 5 to 10 times higher Cu concentration than in the fluids associated with the massive pyrite mineralization. Overall, the hydrothermal system of Mt Morgan is characterized by low average fluid salinities in both mineralization styles (45–80% seawater salinity) and temperatures of 210 to 270 °C estimated from fluid inclusions. Laser Raman Spectroscopic analysis indicates a consistent and uniform array of CO2-bearing fluids. Comparison with active submarine hydrothermal vents shows an enrichment of the Mt Morgan fluids in base metals. Therefore, a seawater-dominated fluid is assumed for the barren massive sulfide mineralization, whereas magmatic volatile contributions are implied for the intrusive related mineralization. Condensation of magmatic vapor into a seawater-dominated environment explains the CO2 occurrence, the low salinities, and the enriched base and precious metal fluid composition that is associated with the Au–Cu mineralization. The sulfur isotope signature of pyrite and chalcopyrite is composed of fractionated Devonian seawater and oxidized magmatic fluids or remobilized sulfur from existing sulfides. Pb isotopes indicate that Au and Cu originated from the Mt Morgan intrusions and a particular volcanic strata that shows elevated Cu background. 相似文献
2.
Xiaofeng Li Yasushi Watanabe Jingwen Mao Shengxiang Liu Xiankui Yi 《Resource Geology》2007,57(3):325-337
The Yinshan deposit in the Jiangnan tectonic belt in South China consists of Pb‐Zn‐Ag and Cu‐Au ore bodies. This deposit contains approximately 83 Mt of the Cu‐Au ores at 0.52% Cu and 0.8 g/t Au, and 84 Mt of the Pb‐Zn‐Ag ores at 1.25% Pb, 1.02% Zn and 33.3 g/t Ag. It is hosted by low‐grade metamorphosed sedimentary rocks and mafic volcanic rocks of the lower Mesoproterozoic Shuangqiaoshan Group, and continental volcanic rocks of the Jurassic Erhuling Group and dacitic subvolcanic rocks. The ore bodies mainly consist of veinlets of sulfide minerals and sulfide‐disseminated rocks, which are divided into Cu‐Au and Pb‐Zn‐Ag ore bodies. The Cu‐Au ore bodies occur in the area close to a dacite porphyry stock (No. 3 stock), whereas Pb‐Zn‐Ag bodies occur in areas distal from the No. 3 stock. Muscovite is the main alteration mineral associated with the Cu‐Au ore bodies, and muscovite and chlorite are associated with the Pb‐Zn‐Ag ores. A zircon sensitive high‐resolution ion microprobe U‐Pb age from the No. 3 dacite stock suggests it was emplaced in Early Jurassic. Three 40Ar‐39Ar incremental‐heating mineral ages from muscovite, which are related to Cu‐Au and Pb‐Zn‐Ag mineralization, yielded 179–175 Ma. These muscovite ages indicate that Cu‐Au mineralization occurred at 178.2±1.4 Ma (2σ), and Pb‐Zn‐Ag mineralization at 175.4±1.2 Ma (2σ) and 175.3±1.1 Ma (2σ), which supports a restricted period for the mineralization. The Early Jurassic ages for the mineralization at Yinshan are similar to that of the porphyry Cu mineralization at Dexing in Jiangnan tectonic belt, and suggest that the polymetallic mineralization occurred in a regional transcompressional tectonic regime. 相似文献
3.
四川呷村VHMS矿床：从矿石化学分析到地球化学模型 总被引：7，自引：2，他引：7
中国四川呷村矿床是一个典型的含金富银多金属VHMS矿床，其主要成矿金属元素Cu,Zn,Pb,Ag,Au丰度型式均呈非正态分布，多由两重或多重母体构成，揭示矿床经历了两次以上的成矿作用过程。成矿金属元素总体上集中于块状矿带，但贱金属Cu,Zn,Pb没有明显的下部富Cu Zn、上部富Pb Zn的分带，贵金属Ag、Au没有显示明显的层位优选性。矿床构造恢复和化学结构图像显示，金属元素的空间分布和富集机制严格受海底凹陷盆地的基底张性断裂和热水喷口位置控制。至少有4条近SN走向的盆地基底断裂带构成海底下部热水流体的迁移－排泄通道和网脉状成矿带的容矿空间；近EW向断裂与4条SN向断裂的交汇部位，成为上排泄的热水流体在海底的主要喷口，控制了金属元素在海底凹地的空间分布。分别处于凹陷盆地东缘和西缘的热水喷口，因正地形地貌形态而形成山丘堆式矿体（mound-syle)，而处于凹陷盆地中心的热水喷口则积聚大量热水流体，构成卤水池，淀积席状块状矿体（sheet-style)。 相似文献
4.
金同铅锌矿化的分离及共生 总被引：5，自引：0，他引：5
金矿化同铅锌矿化存在独特的关系。在块状硫化物矿床和现代洋底硫化物堆积物中金和贱金属的富集程度基本上是相同的,而脉状金矿床中,在富集了大约１０＾３－１０＾４的金的同时仅轻度富集或实际上贫化贱金属铅锌; 相似文献
5.
The Tiemurt Pb-Zn-Cu deposit (metal reserve: 0.29 Mt (Pb + Zn) and 0.14 Mt Cu) is hosted in the Kangbutiebao Formation volcanic-sedimentary rocks in the Chinese Altay Orogen, NW China. Although some geological and geochemical characteristics of primary seafloor sedimentary mineralization are preserved, major fault-controlled Pb-Zn-Cu orebodies are adjacent to the Sarekbuobu orogenic gold deposit, and therefore it is also interpreted to be closely related to regional deformational-metamorphic processes. The seafloor sedimentary mineralization is evidenced by the occurrence of the banded ores and marine sulfate-originated sulfur isotopic compositions of the sulfides (bimodal δ34S values of 17.29–18.67‰ and −25.03 to −17.58‰). The lead isotope compositions accord with the evolution line of mantle, implying that the Pb were chiefly sourced from the mantle-reservoir. The later deformational and metamorphic overprinting are recorded by the fault-controlled lodes with ore textures of epigenetic infilling and replacement. Besides well-developed CO2-rich fluid inclusions, the D-O isotopic data of the overprinting fluids fall into the area between metamorphic fluids and meteoric water line, indicative of metamorphic fluids origin with meteoric water involvement. To further trace the Pb-Zn-Cu accumulation and remobilization processes, systematic in-situ trace elements in sulfides of different generations are analyzed using LA-ICP-MS. Ti-Mn-Cu-Pb-Zn-Bi concentrations in pyrite show a trend of progressive decrease from early to late generations. Similar decreasing trends of trace element concentrations are also present in sphalerite, galena, chalcopyrite and pyrrhotite, although the combinations of trace element are slightly different. This indicates that the ore-forming metals (esp. Cu, Pb and Zn) were initially locked up in the crystal lattice of the VMS sulfides (especially pyrite). Deformational and metamorphic processes of the primary ores during the Permian-Triassic collisional orogeny have likely led to trace element remobilization and sulfides purification, which redistributed the metals and upgraded the ores. Combined with previous studies, we proposed that the Pb-Zn-Cu of Tiemurt had been accumulated from seafloor sedimentation (ca. 400 Ma) to deformation-metamorphism processes (ca. 240 Ma). 相似文献
6.
7.
The Dabaoshan polymetallic deposit, located in the middle Nanling metallogenic belt, is an important and representative W-Mo-Cu-Pb-Zn deposit in the northern Guangdong. The deposit is characterized by a complex combination of ore-forming elements, containing 0.86 Mt Cu, 0.85 Mt Zn, 0.31 Mt Pb, 0.14 Mt WO3 at grades of 0.86%, 12%, 1.77% and 0.12%, respectively. Due to different mineral association and occurrence, mineralization at Dabaoshan can be defined as three types: porphyry W-Mo mineralization, skarn Mo-W mineralization and strata-bound sulfide mineralization. Pyrite from the three-mineralization types has different textures and element compositions. EMPA mapping analysis suggested that distribution of Co, Ni, and As is nearly homogeneous, whilst As in pyrite from the stratabound sulfides shows weak irregular zoning. LA-ICP-MS analyses of pyrite suggested that the three type have distinctive trace element characteristics even though the concentrations of the trace elements are relatively low. Cobalt, Ni, As and Se substitutes Fe and S in pyrite respectively while Cu, Zn, Sn Sb are mainly represented by chalcopyrite, sphalerite, cassiterite and stibnite inclusions enclosed in pyrite. Ni and Ag are rich in the pyrite from the stratabound mineralization. The results suggested that the trace element characteristic of pyrite can be used to: a) study the occurrence of trace element in pyrite; b) imply the chemical-physical conditions; c) trace the regional ore-forming substance and ore forming process. The stratabound mineralization is formed during the volcano eruption during the Devonian then and overprinted by the deep source material and multiple ore-forming fluids in the Yanshanian period. © 2018, Science Press. All right reserved. 相似文献
8.
古代与现代海底黑矿型块状硫化物矿床矿石地球化学比较研究 总被引：33，自引：1，他引：33
选择西南太平洋冲绳海槽现代海底烟囱硫化物矿床、日本小坂矿山上向黑矿（第三纪）和中国西南呷村黑矿型矿床（三叠纪）进行了矿石地球化学比较研究。黑矿型矿床矿石吨位－品位模式与其他火山成因块状硫化物（ＶＭＳ）矿床类似，矿田（２０－５０ｋｍ＾２）矿石吨位与单个喷气－沉积型（Ｓｅｄｅｘ）矿床相当，金属总量４－６Ｍｔ，为矿田范围内热液流体搬运的最大金属量。与洋脊环境ＶＭＳ矿床相比，岛弧裂谷环境产出的黑矿型矿床相 相似文献
9.
The Huangshaping Pb–Zn–W–Mo polymetallic deposit, located in southern Hunan Province, China, is one of the largest deposits in the region and is unique for its metals combination of Pb–Zn–W–Mo and the occurrence of significant reserves of all these metals. The deposit contains disseminated scheelite and molybdenite within a skarn zone located between Jurassic granitoids and Carboniferous sedimentary carbonate, and sulfide ores located within distal carbonate-hosted stratiform orebodies. The metals and fluids that formed the W–Mo mineralization were derived from granitoids, as indicated by their close spatial and temporal relationships. However, the source of the Pb–Zn mineralization in this deposit remains controversial.Here, we present new sulfur, lead, and strontium isotope data of sulfide minerals (pyrrhotite, sphalerite, galena, and pyrite) from the Pb–Zn mineralization within the deposit, and these data are compared with those of granitoids and sedimentary carbonate in the Huangshaping deposit, thereby providing insights into the genesis of the Pb–Zn mineralization. These data indicate that the sulfide ores from deep levels in the Huangshaping deposit have lower and more consistent δ34S values (− 96 m level: + 4.4‰ to + 6.6‰, n = 13) than sulfides within the shallow part of the deposit (20 m level: + 8.3‰ to + 16.3‰, n = 19). The δ34S values of deep sulfides are compositionally similar to those of magmatic sulfur within southern Hunan Province, whereas the shallower sulfides most likely contain reduced sulfur derived from evaporite sediments. The sulfide ores in the Huangshaping deposit have initial 87Sr/86Sr ratios (0.707662–0.709846) that lie between the values of granitoids (0.709654–0.718271) and sedimentary carbonate (0.707484–0.708034) in the Huangshaping deposit, but the ratios decreased with time, indicating that the ore-forming fluids were a combination of magmatic and formation-derived fluids, with the influence of the latter increasing over time. The lead isotopic compositions of sulfide ores do not correlate with sulfide type and define a linear trend in a 207Pb/204Pb vs. 206Pb/204Pb diagram that is distinct from the composition of the disseminated pyrite within sedimentary carbonates and granitoids in the Huangshaping deposit, but is similar to the lead isotopic composition of sulfides within coeval skarn Pb–Zn deposits in southern Hunan Province. In addition, the sulfide ores have old signatures with relative high 207Pb/206Pb ratios, suggesting that the underlying Paleoproterozoic basement within southern Hunan Province may be the source of metals within the Huangshaping deposit.The isotope geochemistry of sulfide ores in the Huangshaping deposit shows a remarkable mixed source of sulfur and ore-forming fluids, and the metals were derived from the basement. These features are not found in representative skarn-type Pb–Zn mineralization located elsewhere. The ore-forming elements (S, Pb, and Zn) from the granitoids made an insignificant contribution to sulfide precipitation in this deposit. However, the emplacement of granitoids did provide large amounts of heat and fluids to the hydrothermal system in this area and extracted metals from the basement rocks, indicating that the Jurassic magmatism associated with the Huangshaping deposit was crucial to the Pb–Zn mineralization. 相似文献
10.
现代海底热液成矿作用研究现状及发展方向 总被引：15，自引：0，他引：15
现代海底热水成矿作用研究的重大进展表现在两个方面：（１）大批活动的和窒息的热液活动区和硫化物矿床在洋脊、岛弧、弧后盆地及板内火山活动中心等海底环境相继发现。在沉积物饥饿洋脊，矿床规模较小，Ｃｕ－Ｚｎ为主，沉积物覆盖洋脊，矿床规模巨大，Ｐｂ－Ｚｎ为主。弧后扩张或弧间裂陷盆地，形成Ｐｂ－Ｚｎ→Ｚｎ－Ｐｂ－Ｃｕ→Ｃｕ－Ｚｎ矿床谱系。岛弧环境硫化物矿床不具规模，板内火山活动中心以氧化物－硫化物矿化为特色。（２）现代海底热水成矿作用观察和研究为古代ＶＭＳ矿床成因研究提供了重要信息，对现有成矿理论产生重要影响。现代成矿观念强调：①海底成矿作用虽可产生于不同环境，但均与张裂断陷事件密切相关。矿床规模和分布特点受张裂速率制约；②成矿物质主体来源于热水循环的火山－沉积岩和下伏基底物质；③硫化物堆积发生于丘堤－烟囱联合构成的机构和结壳下部，通过开放空间的硫化物充填和先成矿石淋滤迁移来实现。④热液流体呈双扩散对流循环。现代海底热水成矿作用的未来研究方向可概括为强度方向和广度方向。广度研究将加大力度去发现新的矿床，强度研究将采用地球物理方法并配以必要的钻探，深入揭示矿床的三维结构和热液体系及成矿机制。 相似文献
11.
新疆阿尔泰萨热阔布-铁木尔特地区两类矿化及成因 总被引：2，自引：0，他引：2
新疆阿尔泰南缘萨热阔布-铁木尔特一带的矿床均赋存于下泥盆统康布铁堡组的变质岩系中。早泥盆世的海相火山形成了Zn--Pb ( Cu) 矿化,晚泥盆世--早石炭世的碰撞造山相应形成了Cu--Au 石英脉矿化; 前者以铁木尔特VMS 型Zn--Pb ( Cu) 矿床为代表,后者以造山型萨热阔布金矿为代表,与造山有关的脉状矿化还叠加在铁木尔特等VMS 矿床中。通过对比两类矿化的稳定同位素特征,结合矿化的变形变质和流体包裹体特征,研究了成矿物质、成矿流体来源和矿床成因。萨热阔布金矿主成矿阶段硫化物石英脉和铁木尔特Zn--Pb ( Cu) 矿床中晚期发育的含黄铜矿石英脉中均富含碳质 ( CO2--CH4--N2 ) 流体包裹体,可能与碰撞造山的热液流体作用有关。铁木尔特Zn--Pb ( Cu) 矿床中代表VMS 期的浸染状矿石中硫化物δ34S 为－26. 46 × 10-3 ～ －19. 72 × 10 -3,硫主要来源于海水硫酸盐的无机还原和细菌还原作用; 而代表后期叠加改造的脉状矿化硫化物值与萨热阔布金矿床硫化物石英脉中δ34S 值接近,硫主要来源于造山过程中的深源流体。萨热阔布金矿床硫化物石英脉和铁木尔特Zn-- Pb ( Cu) 矿床晚期含黄铜矿石英脉的δDH2O 值和δ18OH2O 值,均反映了碰撞造山期热液与岩浆活动和变质作用有关。萨热阔布金矿硫化物石英脉中碳质流体包裹体CO2 体系中δ13 C 为－ 21. 15 × 10-3 ～ －7. 51 × 10 -3,CH4 体系的δ13C 为－34. 11 × 10 -3 ～ －28. 38 × 10-3 ; 铁木尔特Zn--Pb ( Cu) 矿床含黄铜矿石英脉中碳质包裹体测得的δ13C 为－8. 02 × 10 -3 ～ －6. 99 × 10 -3,δ13 C 特征与海相火山沉积无关,具岩浆源或深部源的特点。 相似文献
12.
Hydrothermal activity in the Obiro deposit embedded in the Tagawa acidic rocks,Uetsu region,NE Japan
The Obiro deposit is located in the Tagawa Acidic Rocks (AR), Uetsu region, NE Japan. The Tagawa AR is composed of a volcanic phase of dacitic welded tuff and a plutonic phase of porphyritic granodiorite. Drill core and ore samples were collected from the deposit and examined by XRD, EPMA, and microthermometry. The drill core samples have suffered pervasively from sericite (illite) alteration, whereas pinkish K‐feldspar alteration halo occur close to veins. The results of EPMA and microthermometry is interpreted as that the magnatic‐hydrothermal fluids has changed as follows; the granodioritic magma intruded at about 1.0 kb and 700°C near the water‐saturated granite solidus; after cooling to about 500°C the fluids boiled according to a change in the pressure regime from lithostatic to hydrostatic; mixing with meteoric water led to sulfide mineralization at around 400°C or less. The main reasons for the mineralization in the Obiro deposit are as follows; the oxidized magma intruded at a shallower level, and thereafter hydrothermal fluids were boiled, resulting in a saline fluid. The saline fluid then dissolved metals such as Pb, Zn, Cu, and Bi, and these metals precipitated during cooling accompanied by dilution of the meteoric water and increasing pH, resulting in decreasing solubility. 相似文献
13.
李梅锌矿床地质特征及其成因 总被引：15，自引：0，他引：15
李梅锌矿床是渔塘超大型铅锌矿床的重要组成部分，是近年运用地洼学说预测，经初步验证查明的大型矿床。主要组分锌＞５％，铅很低。矿体主要赋存于下寒武统清虚洞组台地边缘藻礁灰岩相中，为同生构造组合、穹窿、北北东和北西西向地洼构造所控。属多因复成矿床，地台阶段主要是矿源层经压溶作用形成构造压溶热液成矿，在地洼阶段可能是渗流热液成矿，铅锌等成矿物质来自寒武纪碳酸盐围岩，主要成于低温。 相似文献
14.
西太平洋冲绳海槽烟囱硫化物矿床矿石化学特征与分带型式 总被引：12，自引：0，他引：12
西太平洋冲绳海槽烟囱式硫化物矿床分布于琉球弧后扩张盆地、产于尹是名洼陷盆地（深１４００ｍ），其特征与日本黑矿类似。硫化物矿石及烟囱主要有３种化学类型：Ｐｂ－Ｚｎ－Ｂａ型、Ｚｎ－Ｐｂ型和Ｃｕ－Ｚｎ型，三者分别代表温度不断升高的热液体系的早、中、晚３个成矿阶段产物，其中，Ｐｂ－Ｚｎ－Ｂａ矿石及烟囱形成于高ｆｏ２环境和高流速、低温、富Ｐｂ、Ｚｎ、Ｂａ热液体系，Ｃｕ－Ｚｎ矿石及烟囱形成于低流速、高温、富Ｃｕ热液体系，Ｚｎ－Ｐｂ矿石则介于其间。硫化物烟囱显示明显的矿物－化学分带。在Ｐｂ－Ｚｎ－Ｂａ矿石（烟囱），Ｚｎ、Ｃｄ集中于烟囱中央，Ｂａ、Ｆｅ、Ａｓ、Ｓｂ、Ａｇ、Ｐｂ集中于烟囱外带，Ｃｕ则富集于烟囱中外部。在Ｃｕ－Ｚｎ矿石，Ａｓ、Ｓｂ、Ｆｅ、Ａｇ、Ａｕ仍富集于烟囱外带，Ｃｕ、Ｚｎ、Ｐｂ则在烟囱中央富集。依此元素化学分带型式，建立了古代黑矿硫化物矿体分带与硫化物堆积模式。 相似文献
15.
《Resource Geology》2018,68(3):258-274
The Dabaoshan deposit in Northern Guangdong Province, South China, is a Cu–Mo–W–Pb–Zn polymetallic deposit, located in the southern part of the Qin–Hang porphyry–skarn Cu–Mo ore belt. The deposit mainly comprises porphyry Mo and stratiform skarn Cu ore deposits. The genesis of the Cu ore deposit has been ascribed to a typical skarn ore deposit formed by the metasomatism of Devonian carbonate rock layers or to a volcanic rock‐hosted massive sulfide deposit formed by marine exhalation. In this paper, we report on the homogenization temperatures and salinities of fluid inclusions and C, H, O, S, and Pb isotopic compositions of fluids and minerals in this deposit. Homogenization temperatures and salinities of fluid inclusions in garnet, diopside, quartz, and calcite provide information on the skarnification, mineralization, and postmineralization stages. The data show that ore‐forming fluids experienced a continuous transition from high temperatures and salinities to low temperatures and salinities over the entire period of mineralization. C, H, and O isotopic compositions indicate that ore‐forming fluids were derived mainly from magmatic water. O isotopic compositions indicate that ore‐forming fluids mingled with atmospheric water during the last stage of mineralization. Sulfur in the ore came mainly from deep magmatic sources. Pb isotopic compositions in the orebody show that almost all the lead in the ore was derived from magma with a crustal source. Combined geological, geophysical, and geochemical data were achieved before we proposed that the Dabaoshan porphyry–skarn Cu–Mo–W–Pb–Zn deposit, as one member of the Qin–Hang porphyry–skarn Cu–Mo ore belt, formed during the Jurassic subduction of the paleo‐Pacific plate beneath the Eurasian continent at quite low angle. NE‐ and EW‐trending structures controlled the emplacement of magmatic rocks in the South China region. In the mining area, the Xiangguanping Fault and its branches were the main conduits for magmatic crystallization and mineralization. The many subfaults, folds, and interlayer fracture zones on both sides of the main fault provided the requisite space for the ore and, together, were the controlling structures of the orebody. 相似文献
16.
The geodynamic evolution, deep structure, and metallogenic regionalization of the Rudny Altai are considered in terms of plate tectonics. The base-metal massive sulfide deposits are genetically related to the group of basalt-andesite-rhyolite sequences formed in rift or island-arc geodynamic setting in the Devonian at the early stage of Hercynian tectogenesis. Taking into account economic reserves of ore and major metals (Cu, Pb, Zn, Au, Ag), as well as lateral and vertical regional metallogenic zoning of the Rudny Altai, the localization of massive sulfide mineralization in ore-bearing structural elements and particular deposits has been specified. The ore productivity of ore-bearing geochronological levels for base metals and the contribution of these levels to the total reserves of the region are characterized in detail. The Rudny Altai basemetal belt is regarded as a continuous ore-bearing structural unit situated in Russia and Kazakhstan. 相似文献
17.
云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带 总被引：10，自引：3，他引：10
通过研究白秧坪、富隆厂、吴底厂、麻栗坪、金满、科登涧等矿床和矿点的矿化脉体中黝铜矿等矿物的铅同位素组成及黝铜矿和白云石的特征元素组成，进一步探讨了成矿流体与矿化分带的关系。结果表明，黝铜矿中Cu分别与As、Sb之间的正、负相关性，白云石中Sr含量与矿床之间相对距离间正相关关系，指示成矿流体由西向东流动；矿石与盆地的中新生界沉积岩系的铅同位素组成相似。不同矿化部位矿石的铅同位素组成与逆冲推覆构造断裂主要围岩铅同位素组成之间的对应关系指示，金属组分可能主要源自盆地中的中新生界沉积岩系，成矿流体与不同围岩之间的相互作用是造成不同部位矿石铅同位素组成不同的主要原因之一。成矿流体的形成、流动和沉淀源自和发生在该区地壳浅部范围。喜马拉雅期青藏高原的隆升，造成了盆地地形西高东低，有利于形成水力梯度，驱动流体由西向东流动。流体以逆冲推覆构造断裂系统作为通道流动，有效地在更大范围内、长期或周期性地从所流经的各种岩石中萃取和迁移金属组分到合适部位富集。 相似文献
18.
Laila Salama El Mostafa Mouguina Essaid El Bachari Larbi Rddad Mohamed Outhounjite Mohamed Essaoudi Lhou Maacha Mohamed Zouhair 《Arabian Journal of Geosciences》2018,11(24):785
Draa Sfar is a polymetallic (Zn–Pb–Cu) volcanogenic massive sulfide deposit with an actual resource of 13 Mt at 4.0% Zn and 1.3% Pb. It is part of the central Jbilets area known for its several Cu–Zn ore deposits. The ore is hosted in the upper Visean-Namurien sedimentary formation. Owing to the complexity of the geology of the ore deposits, numerical simulation approach was attempted to shed light into the temperature distribution, the circulation of the hydrothermal fluid and the genesis of massive sulfide ore bodies by evaluating the permeability, porosity, and thermal conductivity. On the basis of this simulation approach, the ore is predicted to be deposited at a temperature ranging between 230 and 290 °C. This temperature range is dependent on the pre-existing temperature of the discharge area where a metal-rich fluid precipitated the ore. The duration of the Draa Sfar ore body formation is predicted to be 15, 000 to 50, 000 years. Based on geological studies of Draa Sfar deposit together with the aforementioned results of the simulation approach, an ore genetic model for the massive sulfide ore bodies is proposed. In this model, the supply of ore-forming fluids is ensured by the combination of seawater and magmatic waters. Magma that generated rhyodacite dome acted as the heat source that remobilized the circulation of these ore-bearing fluids. The NW-SE trending faults acted as potential pathways for both the downward and upward migration of the ore-forming fluids. Due to their high permeability, the ignimbritic facies, host rocks of Draa Sfar ore bodies, have favored the circulation of the fluids. The mixing between the ore-forming fluids of magmatic origin and the descending seawaters and/or in situ pore waters led to the formation the ore bodies in 35,000 years. The position and size of the ore body, determined by the simulation approach, is consistent with the actual field geological data. 相似文献
19.
The problem of using surface geochemical exploration techniques in areas of very thick and electrically conductive weathering residuum is common to much of Australia. At the Elura deposit (New South Wales) a distinct electrogeochemical H+ anomaly can be detected in the top few cm of residual soil above about 100 m of conductive residual overburden. In the present paper the results of an investigation of the much more difficult problem of detecting sulfide mineralization beneath thick conductive transported overburden are described.The objective of the study was to demonstrate that sulfide mineralization beneath thick transported overburden can be detected by geochemical patterns in surface soils in the context of an electrogeochemical model of dispersion.The Thalanga massive sulfide deposit in northeast Queensland has at least 4 million tonnes of 15% combined Zn, Pb and Cu. The mineralized horizon lies at the contact between rhyolitic and dacitic rocks of the Cambro-Ordovician Mt. Windsor Volcanics. The deposit is covered by transported cemented Tertiary terrigenous clayey sandstones and grits; these are electrically conductive and vary in thickness from 0 to 70 m.Near-surface soil samples were collected along five traverses normal to the strike of mineralization. The traverses were located to give 0 m, 1 m, 30 m, 50 m, and 70 m overburden thicknesses; there is no known significant mineralization along the last traverse which is assumed to be background, and there is a small gossan where the overburden is absent.Dispersion patterns influenced by electrogeochemical processes should result in relatively low values for ions over massive sulfides with lateral peaks; this has been termed a “rabbit-ear” anomaly. “Rabbit-ear” anomalies in surface soils for H+, Cu, and Zn occur over the sulfide zone. The H+ pattern is better defined where there is a significant depth of overburden (where the anomaly is about 500 m wide). The Cu anomaly is 300–600 m wide, and the Zn anomaly is 450–675 m wide.Even where the overburden is 50 m thick, anomalous “rabbit-ear” anomalies for H+ and Zn are clearly identifiable, but the anomaly for Cu is a single peak of 20 ppm over the hanging wall. It is suggested that the results of this work convincingly demonstrate that at Thalanga surface soil samples may reliably be used to detect massive sulfide deposits - even where they are effectively blind beneath a considerable thickness of transported and conductive overburden. The processes of dispersion are speculated to be diffusion, and it is argued that the pattern-controlling mechanism is electrochemical. 相似文献
20.
激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)是一种固体微区分析新技术。用该技术来分析矿床中硫化物的微量元素组成可以为研究成矿流体特征、矿床成因及找矿勘探提供有关的科学信息。文中以安徽铜陵矿集区内新桥Cu-Au-S矿床中的黄铁矿为研究对象,在详细的野外观察和室内鉴定的基础上,将矿床中的黄铁矿分为具有沉积特征的胶状黄铁矿(PyⅠ)、具有变形重结晶和热液叠加作用特征的细粒他形黄铁矿(PyⅡ)和具热液成因特征的中—粗粒自形黄铁矿(PyⅢ)3种类型。LA-ICP-MS原位微量元素测定结果显示,PyⅠ中相对富含Ti、Co、Ni、As、Se、Te;PyⅡ继承了PyⅠ中富含Ti、Co、Ni、As、Se、Te、Bi的特征,同时还含有不均匀分布的少量成矿元素(Cu、Pb、Zn、Au、Ag);PyⅢ中成矿元素Cu、Pb、Zn、Ag、Au以及Bi元素的含量较高,Co、Ni、As的含量较低。在元素赋存状态方面,Co、Ni、As、Se和Te均以类质同象的形式进入到了黄铁矿的晶格中;Bi在PyⅡ中主要以含Bi矿物的微细包裹体形式存在,而在PyⅢ中的Bi还部分取代了Fe而占据了晶格;Cu、Pb、Zn、Au、Ag这些成矿元素中,Cu和Zn分别以黄铜矿和闪锌矿的矿物包裹体存在于黄铁矿中;PyⅡ中所含的少量Au、Ag,可能分别以自然金和自然银的形式存在,而在PyⅢ中Au可能主要以银金矿的形式存在,Ag除了以银金矿的形式存在以外还可能赋存于黄铁矿中含铋的矿物包裹体内;Pb主要赋存于黄铁矿中的方铅矿或含铋矿物的包裹体中。在综合分析黄铁矿的结构形态和微量元素组成特征的基础上认为,PyⅠ型黄铁矿可能形成于前人提出的晚古生代海底沉积或喷流沉积环境,PyⅡ和PyⅢ型黄铁矿分别形成于中生代区域构造变形-热液叠加改造的过渡环境和热液环境,PyⅡ和PyⅢ的形成时间相近。新桥矿床的形成可能经历了晚古生代海底沉积或喷流沉积期和燕山期热液期,胶黄铁矿主要形成于沉积成矿期,而矿床中成矿物质Cu、Pb、Zn、Au、Ag等主要来自燕山期岩浆侵入作用形成的热液成矿系统。 相似文献