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1.
Gold mineralization at Kundarkocha, India, is hosted in sheared gray quartz veins that were emplaced in carbonaceous pyritic phyllite. Gold occurs as enclosed grains within sulfides and free grains in quartz. Based on characteristic textural and chemical features, documented by X-ray element imaging, electron probe microanalysis and laser-ablation inductively-coupled plasma mass spectrometry analyses, four pyrite types were identified in carbonaceous phyllites and auriferous veins. Rock-hosted fine-grained syn-sedimentary to early diagenetic pyrite framboids (PyI) have lower contents of Co and As but consistently high gold values. Pyrite of the next generation (PyII) has numerous silicate and rare sulfide inclusions; lower contents of Co and Ni, moderate As values; the highest mean value of invisible gold and maximum concentrations of trace elements such as Li, Ti, Zn, Rb, Sr, Y, Zr, Nb, La, Ce, Ta, Th, U and Cr. Pyrite of the third generation (PyIII) shows evidence of overgrowth over PyII, contains both silicate and sulfide inclusions, and are characterized by moderate contents of Co, high Ni and low Au values and higher concentrations of large ion lithophile elements, but lesser amount of high field strength elements. Pyrites of the latest type (PyIV) occur as polycrystalline aggregates that contain inclusions of gold, sulfides and rare silicates, show oscillatory zoning of Co and As and the lowest concentrations of all other trace elements. Successive decrease in contents of majority of trace elements from PyII to PyIV is attributed to fluid-assisted recrystallization during diagenesis and low grade metamorphism.Later generation pyrites (PyII through PyIV) exhibit higher Au contents regardless of their As values, indicating occurrence of invisible gold mostly as nanoparticles, at times reaching up to 500 ppm. Unlike the majority of trace elements that underwent large-scale remobilizations, gold was somehow locked up in pyrite resulting in a rather lean deposit at Kundarkocha. 相似文献
2.
Pyrite textures in five stratiform lead-zinc deposits from lower to upper greenschist facies environment of the Canadian Cordillera
are described and discussed in terms of deposition/early diagenesis, deformation, metamorphism and hydrothermal alteration
processes. Overgrowth is an important process during both diagenesis and deformation. Diagenetic and deformational overgrowths
can be distinguished. Diffusive mass transfer, involving pressure solution and oriented overgrowth of pyrite is the main deformation
mechanism in pyrite deposits at low metamorphic grades. Although diffusive mass transfer favours fine-grained mineral aggregates,
its effect on coarse pyrite grains has also been identified. Ore minerals dissolved by pressure solution may be transported,
with the assistance of pore fluids within fractures and grain boundaries, over distances significantly greater than the scale
of individual grains to give a range of pressure solution/overgrowth textures. The textural modification of pyritic ores from
the early stages of diagnesis, through metamorphism and deformation, to post deformation thermal annealing, has important
implications for the distribution of trace elements and isotopic compositions in pyritic ores. 相似文献
3.
The ～200-km-long intensely deformed Singhbhum Shear Zone (SSZ) in eastern India hosts India’s largest U and Cu deposits and related Fe mineralization. The SSZ separates an Archaean cratonic nucleus to the south from a Mesoproterozoic fold belt in the North and has a complex geologic history that obscures the origin of the contained iron-oxide-rich mineral deposits. This study investigates aspects of the history of mineralization in the SSZ by utilizing new petrographic and electron microprobe observations of pyrite textures and zoning in the Turamdih U–Cu(–Fe) deposit. Mineralization at Turamdih is hosted in intensively deformed quartz–chlorite schist. Sulfides and oxides include, in inferred order of development: (a) magmatic Fe(–Ti–Cr) oxide and Fe–Cu(–Ni) sulfide minerals inferred to be magmatic (?) in origin; followed by (b) uranium, Fe-oxide, and Fe–Cu(–Co) sulfide minerals that predate most or all ductile deformation, and are inferred to be of hydrothermal origin; and (c) Fe–Cu sulfides that were generated during and postdating ductile deformation. These features are associated with the formation of three compositionally and texturally distinct pyrites. Pyrite (type-A), typically in globular–semiglobular composite inclusions of pyrite plus chalcopyrite in magnetite, is characterized by very high Ni content (up to 30,700 ppm) and low Co to Ni ratios (0.01–0.61). The textural and compositional characteristics of associated chalcopyrite and rare pyrrhotite suggest that this pyrite could be linked to the magmatic event via selective replacement of magmatic pyrrhotite. Alternatively, this pyrite and associated sulfide inclusions might be cogenetic with hydrothermal Fe-oxide. Type-B pyrite that forms elongate grains and irregular relics and cores of pyrite with high Co contents (up to 23,630 ppm) and high Co to Ni ratios (7.2–140.9) are interpreted to be related to hydrothermal mineralization predating ductile deformation. A third generation of pyrite (type C) with low Co, low Ni, and moderate Co to Ni ratios (0.19–13.93) formed during and postdating the ductile deformation stage overgrowing, replacing, and surrounding type-B pyrite. The textural evolution of pyrite parallels the tectonometamorphic evolution of the shear zone demonstrating grain elongation during progressive ductile deformation and prograde metamorphism, annealing at the peak metamorphic condition, porphyroblastic growth at the retrograde path and cataclasis following porphyroblastic growth. Compositional characteristics of hydrothermal pyrite and available geological information suggest that the U–Cu(–Fe) deposit at Turamdih might be a variant of the Fe oxide (–Cu–U–rare earth elements) family of deposits. 相似文献
4.
Sulfide minerals in coal bed III at the Chinook Mine, Indiana, are pyrite, marcasite, and rarely sphalerite. Pyrite occurs as framboids concentrated mainly in exinite, as bands or lenses in vitrinite and clay partings, as cell fillings in fusinite, and in cleats. Marcasite normally occurs in association with clusters of pyrite framboids within micro-organic remains. Sphalerite occurs exclusively in fusinite associated with cleat pyrite. The iron sulfides, which are of authigenic origin, were formed during the biochemical stage of coalification during the accumulation and compaction of peat. The factor that limited their formation in such an environment was the availability and reactivity of iron. Chemical heterogeneity in the peat swamps where the sulfides formed existed even on a microscopic scale. The iron sulfides were commonly precipitated in localized micro-environments that were favorable for their formation. The metamorphic stage of coalification did not affect the iron sulfides significantly, although it may have been responsible for the recrystallization of pyrite framboids and minor deformation of pyrite in fusinite and its local mobilisation. 相似文献
5.
I. V. Vikentyev 《Mineralogy and Petrology》2006,87(3-4):305-326
Summary The study focuses on the mode of occurrence of Au, Ag and Te in ores of the Gaisk, Safyanovsk, Uzelginsk and other volcanic-hosted
massive sulfide (VHMS) deposits in the Russian Urals. Minerals containing these elements routinely form fine inclusions within
common sulfides (pyrite, chalcopyrite and sphalerite). Gold is mostly concentrated as ‘invisible’ gold within pyrite and chalcopyrite
at concentrations of 1–20 ppm. Silver mainly occurs substituted in tennantite (0.1–6 wt.% Ag). In the early stages of mineralization,
gold is concentrated into solid solution within the sulfides and does not form discrete minerals. Mineral parageneses identified
in the VHMS deposits that contain discrete gold- and gold-bearing minerals, including native gold, other native elements,
various tellurides and tennantite, were formed only in the latest stages of mineralization. Secondary hydrothermal stages
and local metamorphism of sulfide ores resulted in redistribution of base and precious metals, refining of the common sulfides,
the appearance of submicroscopic and microscopic inclusions of Au–Ag alloys (fineness 0.440–0.975) and segregation of trace
elements into new, discrete minerals. The latter include Au and Ag compounds combined with Te, Se, Bi and S. Numerous tellurides
(altaite, hessite, stützite, petzite, krennerite etc.) are found in the massive sulfide ores of the Urals and appear to be
major carriers of gold and PGE in VHMS ores. 相似文献
6.
I. S. McCallum M. W. Thurber H. E. O'Brien B. K. Nelson 《Contributions to Mineralogy and Petrology》1999,137(3):206-219
Isotopic ratios of Pb in sulfide minerals (primarily pyrrhotite, chalcopyrite, and pentlandite) from a suite of samples from
the platiniferous J-M Reef of the Stillwater Complex were measured to elucidate the temporal and genetic relationship between
sulfides and host silicate minerals. Results indicate that sulfides and coexisting plagioclases are generally not in isotopic
equilibrium, that both sulfides and feldspars record highly radiogenic initial ratios at 2.7 Ga, and that a component of “post-emplacement”
radiogenic Pb has mixed with common Pb in the sulfides. A model involving introduction of radiogenic Pb carried by fluids
derived from sources external to the complex is favored. Analyses of the lead isotopic composition of sulfides in veins which
cut the complex indicate that a significant fraction of the radiogenic lead which was added to the sulfides was externally
derived during an extensive hydrothermal episode, associated with Proterozoic regional metamorphism around 1.7 Ga. The possibility
that some fractions of the radiogenic Pb may have been derived from primary minerals altered during the low-grade metamorphism
cannot be discounted. The amount of radiogenic lead added is variable and in some cases negligible. There is a good correlation
between the lead isotope composition and the nature of the secondary mineral assemblage. Sulfides and plagioclases in samples
that show little or no alteration of the primary minerals are generally in isotopic equilibrium and preserve isotope ratios
consistent with magmatic crystallization at 2.7 Ga. Samples with the most radiogenic sulfides contain abundant secondary minerals
(serpentine, talc, actinolite, chlorite and zoisite) associated with greenschist facies metamorphism. Some of the radiogenic
Pb in the sulfides can be removed by progressive stepwise leaching. However, in most samples recrystallization of sulfides
during metamorphism has mixed common Pb and radiogenic Pb throughout the crystal structure such that, in these samples, stepwise
leaching does not recover initial Pb isotopic ratios. Plagioclases are much more resistant to low temperature recrystallization
and in almost all cases, stepwise leaching reveals the initial lead isotopic composition. The reactivity of sulfides over
a wide temperature range enhances their utility in understanding not only the processes involved in their formation at the
time of magmatic emplacement but also postmagmatic processes which were important in the redistribution and enrichment of
platinum group elements (PGE) within the ore zone.
Received: 30 December 1998 / Accepted: 16 June 1999 相似文献
7.
黄铁矿载金的原因和特征 总被引：21，自引：0，他引：21
对102个金矿床载金矿物的统计表明,黄铁矿是最普遍最重要的载金矿物。造成黄铁矿成为主要载金矿物的原因,有三个矿物学方面的因素,即结构因素、成核因素和电化学因素。结构因素表现在黄铁矿晶体结构中存在对硫 ［S2］2－,对硫 形成过程中对金离子具还原效应。成核因素表现在自然金成核常选择原子排布与之最接近的黄铁矿表面为衬底,以降低成核能。电化学因素表现在黄铁矿的热电性导致金离子在其表面发生电化学反应而沉淀结晶。对黄铁矿载金能力的分析表明,细粒、它形、裂隙发育程度高、As和Sb含量高以及P型的黄铁矿载金能力高,自形黄铁矿中的{210}、S面{100}及其聚形晶的载金能力高。 相似文献
8.
The Central Asian Orogenic Belt,as one of world-class gold economic belts,preserves a number of giant,large black shale-hosted gold deposits,while it is still debated for origin of sulfides and gold mainly due to lack of identification for multiple stages of sulfides.The Haoyaoerhudong gold deposit is hosted in a sequence of Mesoproterozoic carbonaceous and pyritic slate,phyllite,and schist that form a tight syncline along the north margin of the North China Craton.Detailed petrography of the host rocks and mineralization have defined five stages of pyrites.The earliest form of pyrite(Py1)occurs as fine-grained dispersed pyrite in black carbonaceous slate and medium-to coarse-grained disseminated pyrite in pyrite-rich layers,contains relative low gold and high arsenic content,indicating a syn-sedimentary or diagenetic in origin.Stage Ⅱ pyrite(Py2)occurs with garnet and quartz inclusions and Py3 occurs as pyrite veins,contains higher gold and lower As content,and are interpreted to have formed from the dissolution-reprecipitation of Py1 during the peak metamorphism or post-peak metamorphism.Stage Ⅳ pyrite(Py4)from the pyrite-quartz veins crosscut the metamorphic garnet,contains the highest gold concentrations and other trace elements,and is considered to have formed post-peak metamorphism.Abundant native gold,electrum,and maldonite occur as inclusions within Py4 and monazite and in fractures that crosscut garnet.While,Py5 with typical remobilized feature is thought to be a product of melting of former pyrites(Py1 to Py4)triggered by the large-scale Hercynian magmatism.The sedimentary/diagenetic Py1 have δ34S values that range from +12.4‰to +16.2‰.Later generations of sulfides,including Py2 to Py5,and Ccp2 to Ccp3,have δ34S values from +9.5‰to +12.7‰.Monazite with maldonite inclusions from quartz-pyrite veins yielded an intercept age of 341.3±6.6 Ma,while coarse grained monazite associated biotite along fractures in the reefs yielded an intercept age of 254.6±8.2 Ma.The paragenetic,textural,chemical,and isotopic data suggest three distinct gold producing episodes at Haoyaoerhudong gold deposit.Gold and arsenic were clearly initially concentrated in organic muds,and enriched along the structures of diagenetic arsenic-rich pyrite.Subsequently,accompanying metamorphism and deformation,gold was liberated from the dissolution of diagenetic pyrites to form the pyrite veins.Finally,accompanying transformation of pyrite into pyrrhotite,gold was released into the metamorphic fluids to become concentrated as native gold,electrum,and maldonite in pyrite-quart veins.Monazite with age of 341 Ma from quartz-pyrite veins suggests that the third major gold mineralizing event in Haoyaoerhudong occurred before the Hercynian magmatism,suggesting that the Haoyaoerhudong deposit is a typical orogenic gold deposit rather than intrusion-related deposit. 相似文献
9.
In unaltered volcanogenic massive sulfide (VMS) ore deposits, variable Rb/Sr ratios in the ore mineral permits application
of the Rb-Sr isotopic method to directly date the time of ore formation. In contrast, post-crystallization deformation and
metamorphism would open the system to metamorphic fluids that would alter elemental ratios. To test whether the Rb-Sr isotopic
systematics in the ore minerals had preserved the formation time in the ∼800 Ma metamorphosed VMS ores within the ∼1 Ga Ambaji-Sendra
arc terrain, Rajasthan, NW India, common sulfides, pyrite and sphalerite from the Pipela Cu-Zn prospect, were analyzed for
their geochemistry and Rb-Sr isotopic systematics. Trace and rare earth elements in these minerals are resident probably at
crystal defects, whereas all inclusions (including those from metamorphic fluids) were removed by a simple crush leach method.
Results of direct dating by the Rb-Sr method to the hydrothermal pyrite yielded an isochron age of 1025±76 Ma with an initial
Sr ratio of 0.7051±0.0006, similar to previously determined zircon U-Pb age of 987 Ma from associated rhyolites. This suggests
the applicability of the crush leach method to date formation time of metamorphosed pyrite ores. 相似文献
10.
Yuanchuan ZHENG Lianxing GU Xiaoqian TANG Zijiang WANG Changzhi WU Wenlan ZHANG Xueyi WU 《Resource Geology》2012,62(2):174-186
We conducted experiments to simulate sulfide remobilisation from sulfide ore. The starting material was from the Hongtoushan massive sulfide deposit, NE China, and is composed of pyrite, pyrrhotite, chalcopyrite, sphalerite, quartz, and silicate minerals. The ore was immersed in a solution of 20 wt.% NaCl for 260 h, and then was mounted in a Changjiang 500 triaxial rock stress machine. After the experiments were performed for 13 h at temperatures of 362, 464, 556 and 682°C, with corresponding confining and axial pressures, the samples were cooled at room temperatures. Our results from all the runs indicate that sulfides can be remobilised both mechanically and chemically, and that remobilisation is enhanced at higher temperatures. Mechanical remobilisation can only take place over limited distances and results in minor differentiation between various sulfide minerals. Distant external remobilisation to form new orebodies is most likely caused by chemical remobilisation. In contrast to plastically deformed areas, space resulting from cataclastic deformation could provide conduits for fluid transport and space for metal precipitation. Remobilised iron sulfides will precipitate as pyrrhotite at high temperatures, but as pyrite when temperature decreases. Furthermore, chalcopyrite is more easily remobilised than sphalerite under the conditions of the present experiments. Remobilisation accompanying deformation and metamorphism may add epigenetic features to syngenetic deposits. 相似文献
11.
12.
黄铁矿是沉积物中较为常见的矿物之一,而草莓状黄铁矿是由等粒度的亚微米级黄铁矿晶体或微晶体紧密堆积而成。基于已有的草莓状黄铁矿相关研究成果,本文综述了草莓状黄铁矿的形成机制,阐述了其对古环境恢复的意义。目前普遍认为草莓状黄铁矿的成因主要有两种,即有机成因和无机成因,前者认为有机质或细菌参与草莓状黄铁矿形成;而后者主要认为过饱和的黄铁矿浓度是微球粒草莓状黄铁矿形成的必备条件。草莓状黄铁矿粒径的大小是其古沉积环境的直接反映,被作为比较可靠的古氧化还原条件判别指标,已被广泛应用于古代及现代海洋沉积物的古环境恢复。目前,虽然草莓状黄铁矿粒径判别古环境的大小及分布范围还不统一,但普遍认为封闭的水体环境（硫化环境）草莓状黄铁矿粒径较小且变化不大,且随着含氧程度增加,草莓状黄铁矿的粒径大小增大且分布范围趋于加宽。 相似文献
13.
Cobalt-bearing pyrite (0.5?C2.0?wt.% Co) is abnormally abundant (up to 35?vol.% of the total volume of the sulfide phase) in some eastern Pyrenean peridotite massifs, compared to pieces of subcontinental mantle studied so far for sulfides. Pyrite occurs as vermicular intergrowths inside pentlandite and/or chalcopyrite or as coarser, blocky grains in the intergranular pores of host peridotites. Those different pyrites are characterized by different platinum-group element systematics (measured by laser ablation microprobe and ICP-MS). Vermicular pyrite intergrown with pentlandite displays Os-, Ir-, Ru- and Rh-enriched chondrite normalized PGE patterns of Monosulfide solid solution (Mss). In contrast, coarse-grained intergranular (??blocky??) pyrites, are PGE-poor. Chalcophile trace elements (i.e. Zn, Pb, Ag, Au) that are not usually concentrated in mantle-derived sulfides were commonly detected. By contrast, selenium contents are generally low, yielding thus pyrite with high S/Se ratio (>105), consistent with a sedimentary sulfur source. Pyrite microtextures and chalcophile trace element contents support a process of assimilation of crustal sulfur from the metamorphosed sedimentary country rocks. These latter generated highly reactive CO2-S fluids, which were injected into structural discontinuities of the lherzolitic bodies. Sulfur has reacted at T?=?300?C550°C with pre-existing, mantle-derived, metal-rich sulfide assemblages (pentlandite-chalcopyrite). Addition of crustal sulfur did produce Mss which, on cooling, exsolved the Os-rich pyrite in addition to pentlandite. The coarse-grained pyrite types have crystallized directly from S-rich fluids. 相似文献
14.
纳米金的迁移富集与黄铁矿富金关系 总被引：5，自引：0，他引：5
黄铁矿是金矿床中常见的矿物,也是重要的载金矿物之一,有的黄铁矿富金,有的黄铁矿不含金或含微量金。为什么黄铁矿对纳米金的吸附作用强？讨论了纳米微粒金与黄铁矿的关系后指出,半导体型黄铁矿有Ｎ型和Ｐ型两种。前者具负热电动势、带负电;后者具正电位带正电荷。当其与ＳｉＯ２水溶液迁移时,若与带正电荷的Ｐ型黄铁矿相遇,即被Ｐ型黄铁矿吸附沉淀成矿。带负电荷的黄铁矿不能吸附带负电荷的纳米金,因而不能成矿。 相似文献
15.
通过对湖南沃溪矿床的宏观至微观尺度上的矿石组构学研究，揭示出矿床系同生热水沉积成因。层状矿体、细脉状矿化以及围岩蚀变之间的空间关系，指示了矿石与其所赋存的围岩同时形成。矿床形成后的变质—变形作用，主要使矿物发生重结晶、碎裂、位错以及小范围的再活化等。 相似文献
16.
滇黔桂“金三角”卡林型金矿含砷黄铁矿和毒砂的矿物学研究 总被引：21，自引：5，他引：16
滇黔桂"金三角"卡林型金矿不同矿床亚类的典型矿床硫化物显微镜下观察和电子探针显微分析(EP-MA)表明,含砷黄铁矿和毒砂是主要的载金矿物.载金黄铁矿主要以环带状含砷黄铁矿、细粒自形含砷黄铁矿为主.环带状黄铁矿核部贫As、Au,富S、Fe,而环带则相反,且Au与As具有正相关关系.核部贫As的黄铁矿成因复杂,既有成矿早阶段的热液成因,又有受热液蚀变交代的沉积成因.核部和环带是不同成矿阶段的产物.元素的相关关系表明环带中As主要取代S的位置.多环带的特点还表明,热液活动是脉动式的,含矿流体化学成分也是在不断变化的.不论是核部还是环带,均有Au含量高出检出限的测点,但环带是主要的载金部位.细粒含砷黄铁矿为均质结构,具有高As、Au,低S、Fe的特点,类似环带状黄铁矿的环带特征,推测与富砷环带是同期热液活动形成的.毒砂-黄铁矿集合体中的黄铁矿分为环带结构和均质结构2种,并分别具有上述2种黄铁矿的特点.载金毒砂可以细分为3个世代,具均质结构,热液成因.各世代毒砂Au含量均有高出检出限的测点,同时Au、As、S、Fe的含量变化不大,均为主成矿阶段的产物.载金矿物的结晶顺序为:贫砷的沉积成因或早阶段热液成因黄铁矿→富砷的细粒黄铁矿颗粒和富砷黄铁矿环带→毒砂.黄铁矿和毒砂中的Au在EPMA微束的分辨率下均显示分布是不均匀的,环带状黄铁矿中Au元素图出现的均匀结构可能为一种假象,说明金主要以"不可见"的纳米级超显微包裹金形式存在,少量为"不可见"晶格金和微米级显微"可见金".整个滇黔桂"金三角"卡林型金矿不同亚类矿床之间的载金矿物特征和金的赋存状态没有本质区别,说明它们具有相同的成矿作用过程和成矿背景. 相似文献
17.
辽宁红透山铜锌块状硫化物矿床的变质变形和成矿组分再活化 总被引：9，自引：5，他引：9
辽宁红透山铜-锌块状硫化物产在太古宙绿岩带中，矿床形成后经历了强烈的变形和变质，变质程度达高级角闪岩相。野外和显微镜研究表明，矿石在进变质过程中发生过强烈的机械再活化和重结晶，但各种进变质结构大部分已被变质峰期的全面重结晶所清除，目前保存着的结构主要是变质峰期和退变质过程的产物。退变质过程以黄铁矿变斑晶生长、矿石糜棱岩的形成、二次退火和化学再活化为特征。矿床中高度富集铜和金的矿石是韧性剪切形成的矿石糜棱岩受退变质流体叠加而成。磁黄铁矿主要是同生沉积后重结晶的产物，另有一部分由退变质热液形成，而黄铁矿变斑晶则有沉积一重结晶、磁黄铁矿退变质脱硫和热液叠加多种成因。世界各地块状硫化物矿床中的磁黄铁矿和黄铁矿各有三种成因类型。磁黄铁矿的类型有：同生沉积．变质重结晶、同生沉积黄铁矿变质和退变质热液充填或交代；黄铁矿的类型有：同生沉积-变质重结晶、磁黄铁矿退变质脱硫和退变质热液充填或交代。红透山矿区的退变质流体具有从早到晚氧逸度升高的趋势。 相似文献
18.
峨口铁矿中硫化物的特征与成因研究 总被引：1，自引：0，他引：1
硫是铁矿中的有害元素。峨口铁矿中硫主要以磁黄铁矿和黄铁矿两种形式存在。本区硫化物有三个形成期次。第五期为变质作用形成的星点状硫化物；第二期为变质后热液阶段形成的脉状硫化物；第三期为后期热液阶段形成的裂隙充填式硫化物。 相似文献
19.
云南富乐铅锌矿床黄铁矿微量(稀散)元素组成及成因信息:LA-ICPMS研究 总被引：2，自引：2，他引：0
川滇黔铅锌矿集区是华南大面积低温成矿域的重要组成部分,区内铅锌矿床是否属于MVT型矿床长期存在争议。该区铅锌矿床以富集Ge等稀散元素为特征,闪锌矿是其主要载体矿物,但稀散元素在黄铁矿中是否富集、赋存状态及微量元素组成特征等研究基本属于空白。本文通过LA-ICPMS研究富乐黄铁矿中微量元素(尤其是稀散元素)的富集特征,发现黄铁矿中也相对富集Ge。本研究样品选自富乐矿床的富乐和富盛两个矿段,包括1350、1410和1536三个中段(由深到浅),LAICPMS分析结果表明,该矿床黄铁矿以富集Cu、As、Co、Ni为特征,局部富集Pb(Sb)和Zn(以方铅矿和闪锌矿显微包裹体形式赋存于黄铁矿中),该类黄铁矿富集的稀散元素主要为Se、Ge及少量Tl、Te,而Cd和In以类质同象形式赋存于含Zn的显微包裹体(闪锌矿)中,类质同象是其余稀散元素主要赋存形式,且黄铁矿中Ge与Cu存在较好相关关系,可能存在Cu~(2+)+Ge~(2+)?2Fe~(2+)耦合置换方式。此外,黄铁矿中稀散元素的富集与成矿元素(特别是Cu)的富集密切相关,随着成矿作用的进行,从矿体深部到浅部,成矿温度逐渐降低,Se/Te比值逐渐升高,且稀散元素与成矿元素呈逐渐增加趋势。研究表明,该矿床黄铁矿的Co/Ni比值基本都小于1. 00,暗示其属于沉积改造型黄铁矿,在Co-Ni和稀散元素Se-Tl含量投影图上,富乐矿床黄铁矿的投影点与MVT型矿床投影区基本一致,而明显有别于SEDEX、VMS和矽卡岩型矿床中黄铁矿的投影区,结合富乐矿床类似于MVT型的地质特征,我们认为富乐矿床属于MVT型铅锌矿床。 相似文献
20.
秦岭卡林型金矿床金、砷地球化学探讨 总被引：16，自引：0，他引：16
讨论了秦岭卡林型金矿床中Ａｕ 、Ａｓ 的元素地球化学、矿物学特征。在含矿岩系中获得的Ａｕ、Ａｓ 等成矿元素初始含量较高,且主要集中在成岩黄铁矿中。在矿石样品中对含砷硫化物矿物的研究表明,Ａｕ 、Ａｓ 在矿物显微结构中具有强的正相关性。在大量金进入到硫化物结构之前,就已有［ＡｓＳ］３ － 的存在。在含砷硫化物矿物中,金多半以一种带电类型（Ａｕ３ ＋） 存在, 它很可能替代铁位置上的过剩砷, 以固溶体方式沉淀于硫化物矿物中。此时, 黄铁矿构成（Ａｕ３ ＋ ,Ｆｅ２ ＋）（［ＡｓＳ］３ － ［Ｓ２］２ － ）,毒砂构成（Ａｕ３ ＋ ,Ｆｅ２ ＋）（［ＡｓＳ］３ － ［ＡｓＳ］３ －） 。通过电子探针（ＥＭＰ） 和透射电镜（ＴＥＭ） 对秦岭卡林型金矿含砷硫化物矿物中金的赋存状态的研究表明,在金的成矿作用早期阶段, 金主要以固溶体形式优先富集于含砷黄铁矿和毒砂及砷黝铜矿之中,并且认为是以金的氧化和砷的还原的共沉淀方式发生的。在此之后的金成矿作用晚期阶段,由于热液蚀变和结晶作用程度的增高,寄主矿物耐熔性质相对降低,加之金本身的聚集能力,和因过量砷加入而造成的含砷硫化物矿物的晶格缺陷,致使已形成的固溶体金以“出溶”形式发生再分布,赋存于硫化物矿物晶粒 相似文献