Pressure Solution of Sulphides in Some Massive Sulphide Zinc—lead Deposits of Western Canada：Its Significance in Mobilization of Ore—forming Materials

Pressure solution is a common phenomenon in massive sulphide zinc-lead deposits of western Canada and may have been an important factor leading to the mobilization of ore-forming materials during diagenesis, deformation and metamorphism of sedimentary ores.The control of ductile shear zones over gold mineralization could be explained in view of pressure solution of gold-bearing miner-als under shearing stress and the tesultant mobilization of this metal.     

Pyrite: physical and chemical textures

Pyrite may crystallize initially in forms as diverse as framboids or cubes depending upon the temperatures and pressures. Fluid-rich diagenesis or low-grade metamorphism clearly results in thorough recrystallization and the common formation of cubes. Once these have formed, the pyrite becomes much more refractory and retains many characteristics even in deposits which have undergone penetrative deformation. This is in strong contrast to the behavior of most of the accompanying sulfides, which often undergo ductile deformation, solid state or chemical remobilization, and annealing. Pyrite deforms sparingly until there is brittle failure; however, there may be significant pyrite corrosion and regrowth during metamorphism as the result of sulfur exchange with other minerals, especially pyrrhotite. Pyrite fabrics may also be significantly modified by pressure solution or Coble creep. Optical microscopic examination and electron microprobe chemical mapping of pyrites from a variety of mineral deposits, including several high-grade metamorphic ones, reveals that the pyrites frequently contain both physical and chemical textures that may be interpreted in terms of the depositional and the post-depositional history of the deposits. Inclusions of sulfides or other minerals reveal information on the timing of the crystallization or recrystallization of the pyrite; chemical mapping of elements such as Ni, Co, and As reveals information on the relative time of transport of these elements in the ore fluids. Received: 19 March 1997 / Accepted: 14 May 1998     

安徽铜陵冬瓜山铜矿床的叠加改造成矿机制：来自矿石结构的证据

长江中、下游地区块状硫化物矿床普遍受到燕山期岩浆及其热液的改造与叠加.本文以铜陵冬瓜山矿床为例,探讨这类矿床的成矿机制.该矿床主要由层状硫化物矿体组成,伴有矽卡岩型和斑岩型矿体.野外地质观察及室内矿相学的研究表明,冬瓜山层状矿体中矿石遭受了强烈的热变质作用及热液交代作用.进变质过程中形成的结构主要为黄铁矿受燕山期岩浆侵...     

Palaeoenvironmental significance of rounded pyrite in siliciclastic sequences of the Late Archaean Witwatersrand Basin: oxygen‐deficient atmosphere or hydrothermal alteration?

Petrographic and sulphur isotope studies support the long‐held contention that rounded grains of pyrite in siliciclastic sequences of the Late Archaean Witwatersrand Supergroup originated as placer grains. The grains are concentrated at sites where detrital heavy minerals are abundant within quartz‐pebble conglomerates and quartzose sandstones. Depositional sites with abundant pyrite are: (1) within the matrix of bar‐type, clast‐supported conglomerates; (2) on scoured or winnowed surfaces; and (3) on stratification planes. The grains are internally compact or porous, with truncation of internal structure at outer margins indicating fragmentation and rounding of pyritic source‐rocks during erosion and sediment transport. A large range in textures reflects source‐rock lithologies, with known varieties linked to sedimentary‐hosted diagenetic pyrite, volcanic‐hosted massive sulphide deposits and hydrothermal pyrite. Laser ablation sulphur isotope analysis of pyrite reveals a broader range in δ³⁴S values (? 5·3 to + 6·7‰) than that of previously reported conventional bulk‐grain analyses (? 1 to + 4‰). Rounded pyrite from the Steyn Reef has significant variation in δ³⁴S values (? 4·7 to + 6·7‰) that establishes heterogeneous sulphur compositions, with even adjacent grains having diverse isotopic signatures. The heterogeneity supports a placer origin for rounded pyrite. Euhedral pyrite and pyrite overgrowths which are undoubtedly authigenic have restricted δ³⁴S values (? 0·5 to + 2·5‰), are chemically distinct from rounded pyrite and are probably the products of metamorphism or hydrothermal alteration. The placer origin of rounded pyrite indicates that pyrite was a stable heavy mineral during erosion and transport in the early atmosphere. Its distribution in three sequences (Witwatersrand Supergroup, Ventersdorp Contact Reef and Black Reef), and in other sequences not linked to Witwatersrand‐type Au‐U ore deposits, implies deposition of redox‐sensitive detrital heavy minerals during the Late Archaean. Consequently, rounded grains of detrital pyrite are strong indicators of an oxygen‐poor atmosphere. While not confirming a placer origin for gold in Witwatersrand Au‐U ore deposits, the palaeoenvironmental significance of rounded pyrite negates its link to hydrothermal mineralization.     

Multi-stage growth and invisible gold distribution in pyrite from the Kundarkocha sediment-hosted gold deposit,eastern India

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.     

Fabrics of deformed sulphides

Determination of preferred orientations in sulphide ores is an important facet in the analysis of the deformation and metamorphism in ore deposits. The methodology and problems of texture determinations in deformed sulphides are briefly reviewed. Deformation mechanisms and texture development in the common sulphide minerals are summarised. Axi-symmetric experimental deformation of galena, sphalerite and chalcopyrite produces similar pole figures with the (110) planes aligned normal to the compression axis. Deformation textures in naturally deformed sulphides however are best preserved in monomineralic ores which have undergone simple shear deformation. These textures can be correlated with the microstructures found in the sulphides. Computer simulations of deformation textures arising from dislocation mechanisms can be used to interpret the textures but the results to date are preliminary. These theoretical models emphasize the importance of the symmetry of the kinematic axes of the deformation, the operative glide systems and the strain history and the deformation path. Little is known, however, of the influence of static and dynamic recrystallisation on sulphide preferred orientations.     

安徽铜陵冬瓜山矿床中磁黄铁矿矿石结构特征及其成因意义

安徽铜陵冬瓜山矿床是长江中下游地区具有代表性的大型层状硫化物矿床,磁黄铁矿为矿床中的主要硫化物矿物.该矿床主要由层状硫化物矿体组成,伴有矽卡岩型和斑岩型矿体.在层状矿体上部,磁黄铁矿主要为块状构造,而层状矿体下部,磁黄铁矿多为层纹状、条带状构造,具有显著的沉积结构构造特征.野外地质观察及室内矿相学研究表明,层状矿体中磁黄铁矿矿石遭受了强烈的变质作用及热液交代作用.进变质过程中形成的结构主要为胶黄铁矿转变为黄铁矿以及进一步变质转变为磁黄铁矿、磁铁矿时形成的交代残留结构.退变质过程则以磁黄铁矿的退火、黄铁矿变斑晶的生长和单纯六方磁黄铁矿的形成为特征.岩浆热液对单纯六方磁黄铁矿的交代作用形成了单斜和六方磁黄铁矿的交生结构.这些结构特征表明层状矿体中的磁黄铁矿并不是岩浆热液成因,而主要为石炭纪同生沉积胶黄铁矿、黄铁矿在燕山期岩浆侵入所引起的热变质作用下脱硫所形成,并在热变质作用之后又受到岩浆热液的叠加交代.磁黄铁矿的结构特征显示冬瓜山矿床的形成经历了同生沉积、热变质、热液交代等多个阶段,支持其为同生沉积-叠加改造型矿床.     

安徽铜陵冬瓜山层控矽卡岩铜矿床形成过程——来自磁黄铁矿的证据

冬瓜山铜矿床是安徽铜陵地区代表性的层控矽卡岩型铜矿床之一,磁黄铁矿是冬瓜山铜矿床中广泛分布的矿石矿物。野外调研与矿相学观察显示,该矿床中的磁黄铁矿矿石具有沉积、热变质和热液交代结构构造。矿物学研究表明,不同矿石中的磁黄铁矿成分差异较大,其Fe含量变化于57.78%～60.67%之间,分属高温六方相和低温单斜相,主要由黄铁矿变质脱硫而成。冬瓜山铜矿的形成可能经历了早期沉积作用、中期热变质作用和晚期岩浆热液交代作用等复杂成矿过程。     

Ore textures and remobilization mechanisms of the Hongtoushan copper–zinc deposit,Liaoning, China

The Hongtoushan copper–zinc deposit is a volcanic-associated massive sulfide deposit in the Archean greenstone belt in Liaoning, China. Polymetamorphism has resulted in changes to the composition and textures of minerals in the deposit, along with remobilization. During metamorphism, the original alteration minerals that formed with the ore minerals, such as chlorite and sericite, were transformed into cordierite, anthophyllite, and phlogopite. After further remobilization, new minerals, such as gahnite and actinolite, were formed. In this process, the original textures were destroyed and new textures were formed, including recrystallization and growth textures, brittle and ductile deformation textures, durchbewegung textures, replacement textures, chalcopyrite disease, and retrograde textures. The ore-forming components underwent two periods of remobilization. In the first (early) stage, mechanical remobilization was important, and formed a high grade Cu–Zn–Au–Ag “ore pillar” along the vertical hinge of a synformal fold. In the second (late) stage, the mixed hydrothermal–mechanical remobilization affected the ores, and was typically characterized by matrix sulfides, together with silicate minerals, moving from the matrix into individual fractured pyrite metablasts and replacing them to varying degrees.     

Windows of metamorphic sulfur liberation in the crust: Implications for gold deposit genesis

Understanding the source of metamorphic sulfur is critical to clarifying the complete cycle of ore genesis, from source to sink, for several mineral deposit types. In this study, a mass balance approach and the thermodynamic computer programs Thermocalc and PerpleX were used to constrain the P-T range of pyrite breakdown to pyrrhotite (which liberates sulfur) in common metamorphic lithologies. The results suggest that most of the continental crust’s metamorphic sulfur is liberated in a relatively narrow temperature-pressure window corresponding to the terminal breakdown of chlorite at moderate to low pressures. This is because pyrite stability is controlled partly by temperature and pressure, and partly by the amount of H₂O present. During prograde metamorphism from the greenschist to the amphibolite facies, metamorphic H₂O is produced primarily through chlorite breakdown in mafic to pelitic bulk compositions. As temperature increases, more sulfur is required from pyrite to maintain equilibrium proportions of H₂O, H₂S and SO₂ in the fluid, and in addition, progressively more sulfur is required at lower pressures. At low temperatures, little sulfur is required by metamorphic fluid released during initial chlorite breakdown, whereas at higher temperatures coinciding with the terminal breakdown of chlorite, not only is more fluid present, but the fluid’s sulfur requirement has also increased dramatically. In this way, metamorphic dehydration drives pyrite breakdown and generation of sulfur-rich hydrothermal fluids at mesothermal conditions. Beyond the chlorite stability field there is minimal metamorphic fluid production, except at low pressures and high temperatures where muscovite can break down without causing melting; conditions that are a long way from typical crustal geotherms. However, deformation also plays a key role in pyrite breakdown. Without deformation, small amounts of fluid in chemical communication with individual pyrite grains will quickly acquire equilibrium concentrations of the sulfur species and minimal pyrite breakdown is necessary. Whereas during deformation, there may be a continuous fluid flux past pyrite grains, promoting ongoing sulfur liberation. In this way, periods of deformation may be the major sulfur-liberating episodes during a metamorphic cycle. Since hydrothermal fluids are inherently buoyant and consequently tend to migrate upwards and towards cooler temperatures through the crust, these results imply that orogenic gold deposits are most likely to form at lower-amphibolite to prehnite-pumpellyite facies conditions, and unlikely to form at higher temperatures. The pressure constraint on metamorphic sulfur liberation implies that tectonic settings that allow prograde metamorphism to follow low pressure P-T-t paths in an occasionally compressional or transpressional environment are necessary. Settings that promote extensive injection of felsic magma into a mid-crust that contains a significant proportion of pyritic carbonaceous metasediment are shown to be ideal for orogenic gold deposit genesis. Inverted back-arc basins are interpreted to be the most favourable of these.     

黔东南坑头金矿床热液蚀变特征及成矿过程研究

黔东南金成矿区位于江南造山带金成矿省的西南端,成矿条件优越。坑头金矿床是黔东南金成矿区的一个中型矿床,在其深部找矿中,发现除石英脉型矿体外,还存在蚀变岩型矿体。然而,这种蚀变岩型矿体的构造形态、蚀变类型、与石英脉型矿体之间关系和金的赋存状态尚不清楚。本研究与当前的勘查工作紧密结合,围绕石英脉型矿体和新发现的蚀变岩型矿体为研究切入点,借助微区分析技术(扫描电镜和电子探针)进行系统的“流体-蚀变-成矿”研究。蚀变矿物金红石矿物化学显示为热液成因,具有典型造山型金矿床的金红石标型特征。围岩的沉积-成岩过程(包括低级变质作用过程),主要形成了草莓状黄铁矿和含铁碳酸盐岩,为后期含金硫化物(黄铁矿和毒砂)的形成提供物质基础(如Fe)。金的成矿富集过程主要经历了绢云母+毒砂+黄铁矿+石英(Ser+Apy+Py+Qtz)阶段、黄铁矿+毒砂+石英(Py+Apy+Qtz)阶段和自然金+石英(Au⁰+Qtz)阶段。在Ser+Apy+Py+Qtz阶段,主要表现为含矿流体与围岩的初级交代,形成大量浸染状黄铁矿+毒砂的硫化带;Py+Apy+Qtz阶段主要为流体沿着剪切带再交代,形成蚀变岩型矿...     

Syngenetic origin for the sediment-hosted disseminated gold deposits in NW Sichuan,China: ore fabric evidence

Sediment-hosted disseminated gold deposits in NW Sichuan China have many features in common with the well-known Carlin-type deposits in the western United States. They are hosted by Middle–Upper Triassic turbidites composed of 1300–4300 m of rhythmically interbedded, slightly metamorphosed calcareous sandstone, siltstone, and slate. The ore bodies are typically layer- or lens-like in shape and generally extend parallel to the stratification of the host sedimentary rocks, with a strike length of tens to several hundreds of meters. The immediate host rocks consist mainly of calcareous slate and siltstone characterized by high contents of organic matter and diagenetic pyrite. The main primary ore minerals associated with gold mineralization include pyrite, arsenopyrite, realgar, and stibnite. Gangue minerals comprise mostly quartz, calcite and dolomite. Gold is extremely fine-grained, usually less than 1 μm, and cannot be seen with an electron microscope.Two types of ore mineralization have been recognized in the deposits. The stratiform ores are composed of rhythmical interbeds of sulfides (e.g., pyrite, arsenopyrite, realgar, stibnite) interpreted to be authigenic and detrital quartz, quartzite, sericite, and graphite of allogenic origin. They were folded and deformed concordantly with host rocks, and grade both vertically and laterally into normal country rocks. Another type of ore forms a network of numerous gold-bearing veins and veinlets of quartz–calcite–sulfides of millimeter-, centimeter-, decimeter-, and even meter-scale in width. The network ore randomly fills fissures, microfissures, and cleavages, but still is stratabound in character. Detailed studies on ore fabrics show abundant evidence for synsedimentary origins, although subsequent diagenesis, metamorphism, tectonic deformation, and epigenetic hydrothermal activity have significantly remolded the primary fabrics. Primary fabrics are shown either by rhythmical interbeds of different mineral components parallel to the bedding, or by the change of grain size of the same minerals such as pyrite, realgar, and stibnite. The layer inhomogeneity of the stratiform ore is clarified by parallel overprints of later schistosity planes, resulting in distinct grain orientation and elongation, aggregate polarization, and undulating extinction of ore minerals, especially of mechanically and chemically extremely mobile ones, such as realgar and stibnite.It is proposed that the stratiform ores in these Chinese deposits were most probably formed concurrently with their host Middle–Upper Triassic turbidites in submarine, hot spring environments, while the network mineralization was formed as a result of complicated processes such as diagenesis, weak metamorphism, tectonic deformation, and epigenetic hydrothermal activity, responsible for the remobilization or reworking of the pre-existing stratiform ores. Geochemical data also support this genetic model.     

湖南沃溪钨-锑-金矿床的矿石组构学特征及其成因意义

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。     

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

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。     

安徽青阳峙门口层状硫铁矿矿床地质特征及成因研究

青阳峙门口层状硫铁矿矿床赋存于石炭纪地层中,矿体主要呈似层状、透镜状;尽管经历了热变质与接触变质作用,但矿体中仍残留胶黄铁矿和菱铁矿,矿石中不仅可以见到交代残余结构,还可见到草莓结构和微层理构造.黄铁矿中砷的质量分数和S/Se,Co/Ni比值显示火山热水沉积特征.同位素分析显示,矿石中硫化物的硫同位素组成表现出火山热水沉积和热液改造特征;矿石中铅同位素组成则显示,黄铁矿中铅以上地壳铅为主,混有少量地幔铅.上述研究表明峙门口层状硫铁矿矿床是由石炭纪喷流沉积形成的层状矿床或矿胚层,经燕山期岩浆热液和构造作用改造所形成.     

青海驼路沟钴(金)矿床形成的构造环境及钴富集成矿机制

驼路沟矿床是近年在青海东昆仑造山带内发现的首例独立大型钴(金)矿床。文章在详细解剖该矿床地质特征的基础上,通过主元素和微量元素地球化学、流体包裹体及氢、氧同位素等研究,重点探讨其形成的地质构造环境及钴的富集成矿机制。该矿床整合产于浅变质火山-沉积岩系中,发育高度富钠的热水沉积岩和典型的热水沉积矿石组构。沉积岩的主元素和特征微量元素地球化学研究表明,该矿床形成于活动大陆边缘的局限裂陷海盆环境。喷气岩和诸类型矿石的稀土元素分布模式与地层围岩相似,均以显著富集轻稀土元素、具明显负铕异常为特征,表明是由在赋矿岩系中深循环的大气降水喷出后在距喷口位置较远处沉积而成。钴成矿流体为NaCl-H2O体系,伴生金矿化流体为NaCl-CO2-H2O-N2体系。钴主要分布在硫化物(如黄铁矿)相中,而钴的进一步富集、钴矿物的出现及增多,与变质程度紧密正相关。驼路沟矿床与世界其他典型层控Co-Cu-Au矿床具有十分相似的特征和钴成矿作用方式,均为同生喷流热水沉积成因。     

拉拉铜矿黄铁矿微量元素地球化学特征及其成因意义

四川会理拉拉铜矿床是我国著名大型富铜矿床,针对该矿床中黄铁矿的微量元素、稀土元素地球化学分析表明:拉拉铜矿经历了早期火山喷发成岩成矿和晚期变质成岩成矿作用.条带状矿石中的黄铁矿Co/Ni比值集中于4.92～79.2之间,落入火山成因黄铁矿区,稀土元素分布具有Eu正异常和轻稀土富集的特征,反映矿床具有伴随河口群火山喷流沉积成岩过程的同生沉积成矿作用.脉状矿石中的黄铁矿Co/Ni比值集中于1.10～3.45,落在热液成因黄铁矿区,稀土元素较河口群岩石及其他典型块状硫化物矿床矿石稀土元素更加富集轻稀土元素,稀土含量变化范围更大,显著的负Eu异常,则又说明,矿床形成的主要成矿作用是伴随新元古代晋宁运动而发生的大规模的变质作用.     

Correlation between distribution and shape of VMS deposits and regional deformation patterns,Skellefte district,northern Sweden

The Skellefte district in northern Sweden is host to abundant volcanogenic massive sulphide (VMS) deposits comprising pyritic, massive, semi-massive and disseminated Zn–Cu–Au ± Pb ores surrounded by disseminated pyrite and with or without stockwork mineralisation. The VMS deposits are associated with Palaeoproterozoic upper crustal extension (D₁) that resulted in the development of normal faults and related transfer faults. The VMS ores formed as sub-seafloor replacement in both felsic volcaniclastic and sedimentary rocks and partly as exhalative deposits within the uppermost part of the volcanic stratigraphy. Subsequently, the district was subjected to deformation (D₂) during crustal shortening. Comparing the distribution of VMS deposits with the regional fault pattern reveals a close spatial relationship of VMS deposits to the faults that formed during crustal extension (D₁) utilising the syn-extensional faults as fluid conduits. Analysing the shape and orientation of VMS ore bodies shows how their deformation pattern mimics those of the hosting structures and results from the overprinting D₂ deformation. Furthermore, regional structural transitions are imitated in the deformation patterns of the ore bodies. Plotting the aspect ratios of VMS ore bodies and the comparison with undeformed equivalents in the Hokuroko district, Japan allow an estimation of apparent strain and show correlation with the D₂ deformation intensity of the certain structural domains. A comparison of the size of VMS deposits with their location shows that the smallest deposits are not related to known high-strain zones and the largest deposits are associated with regional-scale high-strain zones. The comparison of distribution and size with the pattern of high-strain zones provides an important tool for regional-scale mineral exploration in the Skellefte district, whereas the analysis of ore body shape and orientation can aid near-mine exploration activities.     

铜陵包村金(铜)矿床中胶状黄铁矿矿物学及成因解析

黄铁矿是安徽铜陵包村金(铜)矿床中主要硫化物,对热液成因的显晶质黄铁矿已有大量研究,而胶状黄铁矿研究较少且成因存在争议.本文以粉晶X射线衍射、扫描电镜(SEM)、透射电镜(TEM)以及拉曼光谱(RS)为主要研究方法和手段,对包村金(铜)矿床中胶状黄铁矿的矿物组成和微结构进行研究.包村胶状黄铁矿主要由黄铁矿组成,含有白铁...     

块状硫化物矿石中硫化物的压溶和增生及成矿意义——以加拿大西部矿床为例

加拿大西部块状硫化物矿石普遍地发生过硫化物的压溶和增生。增生作用根据增生体的成分可以分为同质增生和异质增生，根据动力环境可以分为静态增生和动态增生。三晶嵌接结构可以是静态增生的产物。压溶和增生是块状硫化物矿床成岩和变质过程中的重要作用。脉石矿物的压溶可使原生矿石就地加富，硫化物的压溶可使成矿物质发生再活化。增生可促进矿质沉淀。富含硫化物的地层之所以能成为地球化学障而有利于后期热液叠加和层控矿床的形成，硫化物晶芽的增生是一种重要机制。