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1
Magnall, Joseph M., Sarah A. Gleeson, and Suzanne Paradis. "A NEW SUBSEAFLOOR REPLACEMENT MODEL FOR THE MACMILLAN PASS CLASTIC-DOMINANT Zn-Pb ± Ba DEPOSITS (YUKON, CANADA)." Economic Geology 115, no. 5 (August 1, 2020): 953–59. http://dx.doi.org/10.5382/econgeo.4719.
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Abstract Sedimentary exhalative (SEDEX) deposits are a subset of sediment-hosted massive sulfide deposits and provide our dominant resource of Zn. In the SEDEX model, base metals (Zn, Pb, Fe) are hydrothermally vented into sulfidic (euxinic) seawater and deposited coevally with the organic-rich mudstone host rock, resulting in laterally extensive layered mineralization. In the Selwyn Basin (Canada) at Macmillan Pass, two deposits (Tom, Jason) are well preserved in a succession of Upper Devonian mudstones and are considered type-characteristic examples of the SEDEX deposit model. As with a number of SEDEX deposits, at Macmillan Pass barite is abundant in the succession hosting hydrothermal mineralization. Early work presented a hydrothermal model for barite formation, in which barite coprecipitated with base metal sulfides in a redox-stratified water column. Recently, however, studies have both proposed an alternative diagenetic model for barite formation and provided more precise constraints on the chemistry of the hydrothermal fluid that entered the vent complexes. Here, we present a new model for Macmillan Pass in which sulfide mineralization occurred entirely within the subsurface. The introduction of hot (300°C) hydrothermal fluids into the shallow subsurface (<1-km depth) resulted in the thermal degradation of organic matter and generated CO2; this promoted barite dissolution, which both provided a source of sulfate for thermochemical sulfate reduction and increased the porosity and permeability within the system. Importantly, there was clear potential for the development of positive feedbacks and self-organization between diagenetic and hydrothermal processes, resulting in highly efficient ore-forming systems. In contrast to the SEDEX model, alteration footprints will be controlled by the mass transfer involved in (barite) replacement reactions rather than hydrothermal venting, and exploration criteria at a district scale should strongly favor highly productive continental margins.
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Tang, Pan, Juxing Tang, Xinghai Lang, Bin Lin, Fuwei Xie, Miao Sun, Faqiao Li, et al. "Biotite Geochemistry and Its Implication for the Difference in Mineralization in the Xiongcun Porphyry Cu–Au Ore District, Tibet." Minerals 13, no. 7 (June 29, 2023): 876. http://dx.doi.org/10.3390/min13070876.
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The Xiongcun Cu–Au ore district is in the southern middle Gangdese Metallogenic Belt, Tibet, and formed during Neo-Tethyan oceanic subduction. The Xiongcun ore district mainly comprises two deposits, the No. I and No. II deposits, which were formed by two individual mineralization events according to deposit geology and Re–Os isotopic dating of molybdenite. The No. I deposit is similar to a reduced porphyry copper–gold deposit, given the widespread occurrence of primary and/or hydrothermal pyrrhotite and common CH4-rich and rare N2-rich fluid inclusions. The No. II deposit, similar to classic oxidized porphyry copper–gold deposits, contains highly oxidized minerals, including magnetite, anhydrite, and hematite. The halogen chemistry of the ore-forming fluid from the No. I and No. II deposits is still unclear. Biotite geochemistry with halogen contents was used to investigate the differences in ore-forming fluid between the No. I and No. II deposits. Hydrothermal biotite from the No. I deposit, usually intergrown with sphalerite, is Mg-rich and classified as phlogopite and Mg-biotite, and hydrothermal biotite from the No. II deposit is classified as Mg-biotite. Hydrothermal biotite from the No. I deposit has significantly higher SiO2, MnO, MgO, F, Li, Sc, Zn, Rb, Tl, and Pb contents and lower Al2O3, FeOtot, Cl, Ba, Cr, V, Co, Ni, Y, Sr, Zr, Th, and Cu contents than the biotite from the No. II deposit. Hydrothermal biotites from the No. I and No. II deposits yield temperatures ranging from 230 °C to 593 °C and 212 °C to 306 °C, respectively. The calculated oxygen fugacity and fugacity ratios indicate that the hydrothermal fluid of the No. I deposit has a higher F content, oxygen fugacity, and log(fHF/fHCl) value and a lower log(fH2O/fHF) value than the hydrothermal fluid from the No. II deposit. The biotite geochemistry shows that the No. I and No. II deposits formed from different hydrothermal fluids. The hydrothermal fluid of the No. I deposit was mixed with meteoric waters containing organic matter, resulting in a decrease in oxygen fugacity and more efficient precipitation of gold. The No. I and No. II deposits were formed by a Cl-rich hydrothermal system conducive to transporting Cu and Au. The decreasing Cl, oxygen fugacity, and temperature may be the key factors in Cu and Au precipitation. Biotite geochemistry allows a more detailed evaluation of the halogen chemistry of hydrothermal fluids and their evolution within porphyry Cu systems.
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Pei, Dian Fei, Sheng Jun Miao, Guan Lin Huang, and Han Chen. "Study on Lognormal Distribution Characteristics of a Hydrothermal Gold Deposit Mineralization in Jiaodong Peninsula, China." Advanced Materials Research 803 (September 2013): 289–94. http://dx.doi.org/10.4028/www.scientific.net/amr.803.289.
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As one of the most important type of gold deposits, hydrothermal gold deposit has become the hot research area of mineral deposits at present and for a long time to come because of its great economic value and ore-prospecting potentials. Mathematical statistics on mineralization abundance, including grade and linear productivity, of a hydrothermal gold deposit in Jiaodong Peninsula, were done. The results show that mineralization abundance of the hydrothermal gold deposit follows lognormal distribution which is consistent with traditional research findings, which have academic significance for further studies on hydrothermal gold mineralization characteristics and deposition mechanism.
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Camprubí, Antoni, Eduardo González-Partida, Antonin Richard, Marie-Christine Boiron, Luis González-Ruiz, César Aguilar-Ramírez, Edith Fuentes-Guzmán, Daniel González-Ruiz, and Claire Legouix. "MVT-Like Fluorite Deposits and Oligocene Magmatic-Hydrothermal Fluorite–Be–U–Mo–P–V Overprints in Northern Coahuila, Mexico." Minerals 9, no. 1 (January 18, 2019): 58. http://dx.doi.org/10.3390/min9010058.
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The formation of most fluorite deposits in northern Coahuila (NE Mexico) is explained by MVT models, and is a part of the metallogenic province of northeastern Mexico. However, fluorite skarn deposits also occur in the same region, and there is evidence for late hydrothermal manifestations with no clear origin and evolution. The latter are the main focus of this study; in particular, F–Be–U–Mo–V–P stringers in the Aguachile-Cuatro Palmas area that overprint preexisting fluorite mantos. The region experienced the emplacement of several intrusives during the Eocene and the Oligocene that are collectively grouped into the East Mexico Alkaline Province (EMAP) and postdate MVT-like deposits. Some of these intrusives have associated skarn deposits; most of them are polymetallic, but the unusual El Pilote deposit contains fluorite mineralisation that was remobilised from MVT-like deposits. The formation of the Aguachile deposit (and, collectively, part of the Cuatro Palmas deposit) has been attributed to a shallow retrograde skarn model. The Cuatro Palmas and Las Alicias fluorite deposits consist of MVT-like deposits overprinted by late hydrothermal fluorite mineralisation rich in Be–U–Mo–V–P, and the Aguachile deposit consists entirely of the latter type. The systematic fluid inclusion study of MVT-like, skarn, and late hydrothermal fluorite deposits reveals a very different distribution of temperature and salinity data that allows the discrimination of mineralising fluids for the type of deposit. MVT-like deposits were formed by fluids with temperatures of homogenisation that range between 50 °C and 152 °C and salinities between 5 and 15.5 wt.% NaCl equivalent. The El Pilote fluorite skarn was formed by fluids with temperatures of homogenisation that range between 78 °C and 394 °C and salinities between 5 and 34 wt.% NaCl equivalent, and include CaCl2-rich brines with salinities that range between 24.5 and 29.1 wt.% CaCl2. Late shallow fluorite–Be–U–Mo–V–P hydrothermal deposits were formed by fluids with temperatures of homogenisation that range between 70 °C and 180 °C and salinities between 0.9 and 3.4 wt.% NaCl equivalent; the sole exception to the above is the La Fácil deposit, with salinities that range between 7.9 and 8.8 wt.% NaCl equivalent. While temperatures of homogenisation are similar between MVT-like and late hydrothermal deposits, and both even have hydrocarbon-rich fluid inclusion associations, the salinity of late deposits is similar to that of retrograde skarn fluids, although further diluted. However, homogenisation temperatures tend to be higher in late hydrothermal than in MVT-like deposits, thus making them more similar to retrograde skarn fluids. Although this characteristic cannot solely establish a genetic link between a retrograde skarn model and late hydrothermal deposits in the study area, the characteristics of fluids associated with the latter separate these deposits from those ascribed to an MVT-like model. Assuming that mineralising fluids for late fluorite–Be–U–Mo–V–P hydrothermal deposits may correspond to a retrograde skarn (or “epithermal”) deposit, the source for fluorine may be either from (A) the dissolution of earlier formed MVT-like deposits, (B) the entrainment of remaining F-rich basinal brines, or (C) hydrothermal fluids exsolved from highly evolved magmas. Possibilities A and B are feasible due to a hypothetical situation similar to the El Pilote skarn, and due to the occurrence of hydrocarbon-rich fluid inclusions at the La Fácil deposit. Possibility C is feasible because intrusive bodies related to highly evolved magmas would have provided other highly lithophile elements like Be, U and Mo upon the exsolution of their hydrothermal fluids. Such intrusive bodies occur in both study areas, and are particularly conspicuous at the Aguachile collapse structure.
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Fox, David C. M., Samuel C. Spinks, Milo Barham, Christopher L. Kirkland, Mark A. Pearce, Mehrooz Aspandiar, Renee Birchall, and Ed Mead. "Working up an Apatite: Enigmatic Mesoarchean Hydrothermal Cu-Co-Au Mineralization in the Pilbara Craton." Economic Geology 116, no. 7 (November 1, 2021): 1561–73. http://dx.doi.org/10.5382/econgeo.4842.
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Abstract Globally, significant examples of hydrothermal Cu-Co mineralization are rare within Archean greenstone belts, especially relative to the endowment of these terranes with other world-class hydrothermal ore deposits, particularly Au deposits. Using U-Pb geochronology of hydrothermal apatite, this study provides the first absolute age constraints on the timing of mineralization for the Carlow Castle Cu-Co-Au deposit. Carlow Castle is a complex, shear zone-hosted, veined Cu-Co-Au mineral system situated within the Paleo-Mesoarchean Roebourne greenstone belt of the Pilbara craton of northwestern Western Australia. Although U-Pb geochronology of this deposit is challenging due to low levels of radiogenic Pb in synmineralization apatite, mineralization is best estimated at 2957 ± 67 Ma (n = 61). Additionally, analysis of alteration phases associated with Carlow Castle mineralization suggests that it is dominated by a propylitic assemblage that is characteristic of alkaline fluid chemistry and peak temperatures >300°C. Within proximal portions of the northwest Pilbara craton, the period of Carlow Castle’s formation constrained here is associated with significant base-metal volcanogenic massive sulfide mineralization and magmatic activity related to back-arc rifting. This rifting and associated magmatic activity are the most likely source of Carlow Castle’s unique Cu-Co-Au mineralization. Carlow Castle’s Mesoarchean mineralization age makes it among the oldest discovered Cu-Co-Au deposits globally, and unique in the broader context of hydrothermal Cu-Co-Au deposits. Globally, hydrothermal Cu-Co mineralization occurs almost exclusively as Proterozoic and Phanerozoic stratiform sediment-hosted Cu-Co deposits due to the necessity of meteorically derived oxidized ore fluids in their formation. This research therefore has implications for exploration for atypical Cu-Co deposits and Cu-Co metallogenesis through recognition of comparably uncommon magmatic-hydrothermal Cu-Co-Au ore-forming processes and, consequently, the potential for analogous Cu-Co-Au mineralization in other Archean greenstone belts.
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Li, Jinwei, Lichuan Pan, Yitong Guo, and Shunfu Lu. "Multi-Isotopic Compositions of Ores from the Shizishan Cu–Au–Mo Orefield in the Tongling Region, Eastern China: Implications for Ore Genesis." Minerals 13, no. 7 (July 24, 2023): 985. http://dx.doi.org/10.3390/min13070985.
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The Middle–Lower Yangtze Metallogenic Belt (MLYMB) hosts abundant porphyry–skarn–stratabound-type Cu–Au–Mo deposits. Despite extensive research, the origin of the stratabound-type deposits, which developed at the unconformity interface between the Devonian and Carboniferous strata in the MLYMB, remains controversial. The primary debate centers on whether these deposits are the result of Carboniferous sedimentary exhalative mineralization or Mesozoic magmatic–hydrothermal mineralization. In this paper, we examine three representative deposits in the Shizishan orefield: the Chaoshan skarn-type Au deposit, the Hucun porphyry–skarn-type Cu–Mo deposit, and the Dongguashan Cu–(Au) deposit, which has a disputed genesis of its stratiform orebodies. Economically important ore minerals, such as chalcopyrite, molybdenite, and pyrrhotite, and their associated quartz and calcite, were focused on, rather than the extensively studied pyrite in the Tongling region. The ore genesis and sources of mineralized elements in the Shizishan orefield were investigated using H, O, C, S, Pb, and Cu isotopes. The H–O isotopic compositions of hydrothermal quartz from the Chaoshan, Dongguashan, and Hucun deposits indicate that the ore-forming fluids were mainly magmatic water with some meteoric water input. The C–O isotopic compositions of calcite show a large difference from the local sedimentary carbonates. The S isotopic compositions of sulfides reveal a magmatic sulfur signature. The Pb isotopic compositions in the three deposits are similar to those of the Shizishan intrusions, suggesting a magmatic source for Pb. The Cu isotopic compositions of chalcopyrite and pyrrhotite demonstrate that Cu, the primary ore-forming element, was mainly derived from magmatic–hydrothermal fluids. The stratiform orebodies display H–O–C–S–Pb–Cu isotopes consistent with the porphyry orebodies in the Dongguashan deposit, as well as in the Chaoshan and Hucun deposits, indicating a common ore genesis. From these, we conclude that the porphyry–skarn–stratabound-type Cu–Au–Mo deposits in the Shizishan orefield can be classified as a unified Mesozoic magmatic–hydrothermal metallogenic system. The stratabound-type copper sulfide deposits and the porphyry–skarn-type copper deposits in the MLYMB have a strong similarity in the source and genesis of their ore-forming elements.
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Lotfi, Mohammad, Mansoureh Shirnavard Shirazi, Nima Nezafati, and Arash Gourabjeripour. "MINERALOGY AND GEOCHEMISTRY STUDY OF REE MINERALS IN HOST ROCKS IN IIC IRON DEPOSIT, BAFGH MINERAL AREA, CENTRAL IRAN." Geosaberes 11 (January 8, 2020): 51. http://dx.doi.org/10.26895/geosaberes.v11i0.909.
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The IIC deposit area to the east of the Bafq region exposes rocks that comprise the part of the Central Iran continental terrane. The IIC deposit iron orebodies are magmatic-related hydrothermal deposits that, when considered collectively display a vertical zonation from high-temperature, magmatic ± hydrothermal deposits emplaced at moderate depths (~1–2 km) to magnetite-dominant IOCG deposits emplaced at an even shallower subvolcanic level. The shallowest parts of these systems include near-surface, iron oxide-only replacement deposits, surficial epithermal sediment-hosted replacement deposits, and synsedimentary (exhalative) ironstone deposits. Alteration associated with the IOCG mineralizing system within the host volcanic, plutonic, and sedimentary rocks dominantly produced potassic with lesser amounts of calcic- and sodic-rich mineral assemblages. Our data suggest that hydrothermal magmatic fluids contributed to formation of the primary sodic and calcic alterations. The aim of this study is to delineate and recognize the different iron mineralized zones, based on surface and subsurface study. However, the data do not discriminate between a magmatic-hydrothermal source fluids resolved from Fe-rich immiscible liquid or Fe-rich silicate magma. Iron ores, occurring as massive-type and vein-type bodies are chemically different. Minor pyrite occurs as a late phase in the iron ores. The REE patterns of the mineralized metasomatites show LREE enrichment and strong Eu negative anomalies. The strong negative Eu anomaly probably indicates near-surface fractionation of alkali rhyolites involving feldspars. Field observations, ore mineral and alteration assemblages, coupled with lithogeochemical data suggest that an evolving fluid from magmatic dominated to surficial brine-rich fluid has contributed to the formation of the IIC deposit.
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Huang, Xiao-Wen, Anne-Aurélie Sappin, Émilie Boutroy, Georges Beaudoin, and Sheida Makvandi. "Trace Element Composition of Igneous and Hydrothermal Magnetite from Porphyry Deposits: Relationship to Deposit Subtypes and Magmatic Affinity." Economic Geology 114, no. 5 (August 1, 2019): 917–52. http://dx.doi.org/10.5382/econgeo.4648.
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Abstract The trace element composition of igneous and hydrothermal magnetite from 19 well-studied porphyry Cu ± Au ± Mo, Mo, and W-Mo deposits was measured by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and then classified by partial least squares-discriminant analysis (PLS-DA) to constrain the factors explaining the relationships between the chemical composition of magnetite and the magmatic affinity and porphyry deposit subtypes. Igneous magnetite can be discriminated by relatively high P, Ti, V, Mn, Zr, Nb, Hf, and Ta contents but low Mg, Si, Co, Ni, Ge, Sb, W, and Pb contents, in contrast to hydrothermal magnetite. Compositional differences between igneous and hydrothermal magnetite are mainly controlled by the temperature, oxygen fugacity, cocrystallized sulfides, and element solubility/mobility that significantly affect the partition coefficients between magnetite and melt/fluids. Binary diagrams based on Ti, V, and Cr contents are not enough to discriminate igneous and hydrothermal magnetite in porphyry deposits. Relatively high Si and Al contents discriminate porphyry W-Mo hydrothermal magnetite, probably reflecting the control by high-Si, highly differentiated, granitic intrusions for this deposit type. Relatively high Mg, Mn, Zr, Nb, Sn, and Hf but low Ti and V contents discriminate porphyry Au-Cu hydrothermal magnetite, most likely resulting from a combination of mafic to intermediate intrusion composition, high chlorine in fluids, relatively high oxygen fugacity, and low-temperature conditions. Igneous or hydrothermal magnetite from Cu-Mo, Cu-Au, and Cu-Mo-Au deposits cannot be discriminated from each other, probably due to similar intermediate to felsic intrusion composition, melt/fluid composition, and conditions such as temperature and oxygen fugacity for the formation of these deposits. The magmatic affinity of porphyritic intrusions exerts some control on the chemical composition of igneous and hydrothermal magnetite in porphyry systems. Igneous and hydrothermal magnetite related to alkaline magma is relatively rich in Mg, Mn, Co, Mo, Sn, and high field strength elements (HFSEs), perhaps due to high concentrations of chlorine and fluorine in magma and exsolved fluids, whereas those related to calc-alkaline magma are relatively rich in Ca but depleted in HFSEs, consistent with the high Ca but low HFSE magma composition. Igneous and hydrothermal magnetite related to high-K calc-alkaline magma is relatively rich in Al, Ti, Sc, and Ta, due to a higher temperature of formation or enrichment of these elements in melt/fluids. Partial least squares-discriminant analysis on hydrothermal magnetite compositions from porphyry Cu, iron oxide copper-gold (IOCG), Kiruna-type iron oxide-apatite (IOA), and skarn deposits around the world identify important discriminant elements for these deposit types. Magnetite from porphyry Cu deposits is characterized by relatively high Ti, V, Zn, and Al contents, whereas that from IOCG deposits can be discriminated from other types of magnetite by its relatively high V, Ni, Ti, and Al contents. IOA magnetite is discriminated by higher V, Ti, and Mg but lower Al contents, whereas skarn magnetite can be separated from magnetite from other deposit types by higher Mn, Mg, Ca, and Zn contents. Decreased Ti and V contents in hydrothermal magnetite from porphyry Cu and IOA, to IOCG, and to skarn deposits may be related to decreasing temperature and increasing oxygen fugacity. The relative depletion of Al in IOA magnetite is due to its low magnetite-silicate melt partition coefficient, immobility of Al in fluids, and earlier, higher-temperature magmatic or magmatic-hydrothermal formation of IOA deposits. The relative enrichment of Ni in IOCG magnetite reflects more mafic magmatic composition and less competition with sulfide, whereas elevated Mn, Mg, Ca, and Zn in skarn magnetite results from enrichment of these elements in fluids via more intensive fluid-carbonate rock interaction.
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Takagi, T., S. M. Koh, M. S. Song, M. Itoh, and K. Mogi. "Geology and properties of the Kawasaki and Dobuyama bentonite deposits of Zao region in northeastern Japan." Clay Minerals 40, no. 3 (September 2005): 333–50. http://dx.doi.org/10.1180/0009855054030177.
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AbstractThe Kawasaki and Dobuyama bentonite deposits in northeastern Japan show contrasting properties even though they are only 5 km apart in a sequence of Neogene sedimentary and pyroclastic rocks. The Kawasaki deposit consists of stratiform bentonite layers up to >50 m thick, and its wall rocks are unaltered shallow marine sedimentary rocks. In contrast, the Dobuyama deposit consists of a funnel-shaped ore body 200 m across, and its wall rocks are hydrothermally altered terrestrial rhyolitic pyroclastic rocks. The Kawasaki and Dobuyama bentonites mainly consist of Na-Ca smectite and Ca smectite, respectively, with subordinate opal-CT, quartz and zeolite. The geological occurrences of the deposits and wall-rock properties suggest that the Kawasaki and Dobuyama deposits were probably formed by diagenesis and low-temperature hydrothermal alteration, respectively. The difference in exchangeable cation ratios of the smectite between the two deposits is attributable to the difference in their sedimentary environments and/or burial depth.
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Wang, Zhen-Yu, Hong-Rui Fan, Lingli Zhou, Kui-Feng Yang, and Hai-Dong She. "Carbonatite-Related REE Deposits: An Overview." Minerals 10, no. 11 (October 28, 2020): 965. http://dx.doi.org/10.3390/min10110965.
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The rare earth elements (REEs) have unique and diverse properties that make them function as an “industrial vitamin” and thus, many countries consider them as strategically important resources. China, responsible for more than 60% of the world’s REE production, is one of the REE-rich countries in the world. Most REE (especially light rare earth elements (LREE)) deposits are closely related to carbonatite in China. Such a type of deposit may also contain appreciable amounts of industrially critical metals, such as Nb, Th and Sc. According to the genesis, the carbonatite-related REE deposits can be divided into three types: primary magmatic type, hydrothermal type and carbonatite weathering-crust type. This paper provides an overview of the carbonatite-related endogenetic REE deposits, i.e., primary magmatic type and hydrothermal type. The carbonatite-related endogenetic REE deposits are mainly distributed in continental margin depression or rift belts, e.g., Bayan Obo REE-Nb-Fe deposit, and orogenic belts on the margin of craton such as the Miaoya Nb-REE deposit. The genesis of carbonatite-related endogenetic REE deposits is still debated. It is generally believed that the carbonatite magma is originated from the low-degree partial melting of the mantle. During the evolution process, the carbonatite rocks or dykes rich in REE were formed through the immiscibility of carbonate-silicate magma and fractional crystallization of carbonate minerals from carbonatite magma. The ore-forming elements are mainly sourced from primitive mantle, with possible contribution of crustal materials that carry a large amount of REE. In the magmatic-hydrothermal system, REEs migrate in the form of complexes, and precipitate corresponding to changes of temperature, pressure, pH and composition of the fluids. A simple magmatic evolution process cannot ensure massive enrichment of REE to economic values. Fractional crystallization of carbonate minerals and immiscibility of melts and hydrothermal fluids in the hydrothermal evolution stage play an important role in upgrading the REE mineralization. Future work of experimental petrology will be fundamental to understand the partitioning behaviors of REE in magmatic-hydrothermal system through simulation of the metallogenic geological environment. Applying “comparative metallogeny” methods to investigate both REE fertile and barren carbonatites will enhance the understanding of factors controlling the fertility.
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Jiang, Shao-Yong, M. R. Palmer, Yan-He Li, and Chun-Ji Xue. "Ba-rich micas from the Yindongzi-Daxigou Pb-Zn-Ag and Fe deposits, Qinling, northwestern China." Mineralogical Magazine 60, no. 400 (June 1996): 433–45. http://dx.doi.org/10.1180/minmag.1996.060.400.05.
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AbstractElectron-microprobe analyses of muscovite, biotite, and feldspar are reported for the stratiform Yindongzi—Daxigou Pb—Zn—Ag and Fe deposits of Qinling, northwestern China. The micas are characterized by high Ba levels in banded albite-carbonate rocks that host the deposits. The biotite is also rich in Cl, as is biotite in the nearby Tongmugou Pb-Zn deposit, although biotite and muscovite from this deposit lack Ba enrichment. It is likely that the Ba-rich micas in the Yindongzi-Daxigou deposits formed contemporaneously from the diagenesis and/or regional metamorphism of hydrothermally altered clay minerals, with the barium being derived from entrained pore fluids that may represent relict hydrothermal fluids associated with ore deposition. During the formation of coexisting muscovite and biotite, barium is preferentially partitioned into muscovite and chloride into biotite. Together with the presence of baryte rocks in the bedded ores, these data suggest that ore deposition in the Yindongzi—Daxigou deposits took place in a more oxidising environment than in the nearby Tongmugou deposit. This difference is attributed to the contrasting sedimentary environments of the two deposits, with the Yindongzi—Daxigou deposits having formed under shallow, oxic conditions and the Tongmugou deposit under deeper, anoxic conditions.
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Д., Доржготов, and Тамир Б. "Монгол орны холимог металын металлогений асуудалд." Геологийн асуудлууд 21, no. 02 (October 31, 2022): 190–200. http://dx.doi.org/10.22353/.v21i02.1260.
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In Mongolia, around 40 deposits of polymetals and 250 occurrences about have been identifie, and they are very different from each other in terms of origin, geological formation, ore composition, and geological and mineralogical characteristics. This of types skarn polymetal, plutonogenic hydrothermal polymetal, volcanogenic hydrothermal massiv sulfide polymetal, volcanogenic hydrothermal massiv sulfide copper-zinc and volcanogenic hydrothermal massiv sulfide lead-silver five production types and one auxiliary type of zinc-lead stratiform are covered. Those kind of deposits and production type of polymetal production were formed during six periods of intense rejuvenated metallogenic from west to east during the period from Proterozoic to Mesozoic, and more than 80% of industrial reserves are estimated in Mesozoic deposits. The distribution and location of polymetals in Mongolia is defined by six metallogenic regions, 13 regions, and 24 districts, which differ in parameters such as tectonic structure type, geological formation, deposit type, etc.
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Gao, Wei, Ruizhong Hu, Albert H. Hofstra, Qiuli Li, Jingjing Zhu, Keqiang Peng, Lan Mu, Yong Huang, Jianwen Ma, and Qiang Zhao. "U-Pb Dating on Hydrothermal Rutile and Monazite from the Badu Gold Deposit Supports an Early Cretaceous Age for Carlin-Type Gold Mineralization in the Youjiang Basin, Southwestern China." Economic Geology 116, no. 6 (September 1, 2021): 1355–85. http://dx.doi.org/10.5382/econgeo.4824.
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Abstract The Youjiang basin on the southwestern margin of the Yangtze block in southwestern China is the world’s second largest Carlin-type gold province after Nevada, USA. The lack of precise age determinations on gold deposits in this province has hindered understanding of their genesis and relation to the geodynamic setting. Although most Carlin-type gold deposits in the basin are hosted in calcareous sedimentary rocks, ~70% of the ore in the Badu Carlin-type gold deposit is hosted by altered and sulfidized dolerite. Although in most respects Badu is similar to other Carlin-type gold deposits in the province, alteration of the unusual dolerite host produced hydrothermal rutile and monazite that can be dated. Field observations show that gold mineralization is spatially associated with, but temporally later than, dolerite. In situ secondary ion mass spectrometry (SIMS) U-Pb dating on magmatic zircon from the least altered dolerite yielded a robust emplacement age of 212.2 ± 1.9 Ma (2σ, mean square of weighted deviates [MSWD] = 0.55), providing a maximum age constraint on gold mineralization. The U-Th/He ages of detrital zircons from hydrothermally mineralized sedimentary host rocks at Badu and four other Carlin-type gold deposits yielded consistent weighted mean ages of 146 to 130 Ma that record cooling from a temperature over 180° to 200°C and place a lower limit on the age of gold mineralization in the basin. Hydrothermal rutile and monazite that are coeval with gold mineralization have been identified in the mineralized dolerite. Rutile is closely associated with hydrothermal ankerite, sericite, and gold-bearing pyrite. It has high concentrations of W, Fe, V, Cr, and Nb, as well as growth zones that are variably enriched in W, Fe, Nb, and U. Monazite contains primary two-phase fluid inclusions and is intergrown with gold-bearing pyrite and hydrothermal minerals. In situ SIMS U-Pb dating of rutile yielded a Tera-Wasserburg lower intercept age of 141.7 ± 5.8 Ma (2σ, MSWD = 1.04) that is within error of the in situ SIMS Th-Pb age of 143.5 ± 1.4 Ma (2σ, MSWD = 1.5) on monazite. These ages are ~70 m.y. younger than magmatic zircons in the host dolerite and are similar to the aforementioned U-Th/He cooling ages on detrital zircons from hydrothermally mineralized sedimentary host rocks. We, therefore, conclude that the Badu Carlin-type gold deposit formed at ca. 144 Ma. The agreement of the rutile and monazite ages with the U-Th-He cooling ages of Badu and four other Carlin-type gold deposits in the Youjiang basin suggests that ca. 144 Ma is representative of a regional Early Cretaceous Carlin-type hydrothermal event formed during back-arc extension.
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Vikentye, I. V., B. B. Damdinov, O. R. Minina, A. V. Spirina, and L. B. Damdinova. "Classification of Polymetallic Ore-Forming Processes and Transitional VMS–SEDEX–MV-type: the Example of the Giant Ozernoe Deposit in Transbaikalia, Russia." Геология рудных месторождений 65, no. 3 (May 1, 2023): 201–36. http://dx.doi.org/10.31857/s001677702303005x.
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This article discusses the general classification approaches and key features of different families of polymetallic deposits, with particular attention to the largest in Eurasia Ozernoe polymetallic deposit located in Western Transbaikalia and thoroughly explored 50 years ago. The main groups (or families) of polymetallic deposits in the English-language literature are identified by brief names: volcanogenic massive sulphide (VMS), sedimentary exhalative (SEDEX), and Mississippi Valley type (MVT). Within these three families of deposits, there are many additional types/subtypes, a large number of which are mostly due to the incompleteness and inconsistency of accumulated knowledge on the genesis of polymetallic deposits. Overall, all Pb–Zn(Ag,Cu) deposits—both those that are considered syngenetic, forming on and near the seafloor (VMS and SEDEX), and epigenetic low-temperature ones (MVT)—demonstrate a wide range of features that distinguish and bring together these families. This also applies to the types and subtypes of mineral deposits identified within them. One of the most complex objects for geological–genetic classification is the Ozernoe deposit studied by the authors, which, in terms of the nature of the host rocks, is intermediate between the end members of all three families: SEDEX, VMS and MVT. The deposit is localized in volcanic–carbonate–terrigenous rocks of the Cambrian Oldynda formation, but the age and stratigraphic affiliation of the ore-bearing series remain a matter of debate. The Ozernoe deposit is a combination of massive sulfide and siderite ore beds, ore breccia horizons, low-carbonate aleuropelite members, limestones, fine detrital tuffites, lavas, and tuffs. The sulfide bodies are confined to several stratigraphic levels, and the main productive unit thickness reaches 230 m. The thickness is comprised of 12 mineral lodes, a series of stratified ore bodies separated by gangue layers of sedimentary and volcaniclastic rocks. The primary ore minerals are pyrite, sphalerite, and galena, while the minor minerals include magnetite, chalcopyrite, marcasite, tetrahedrite, and arsenopyrite. There are two main theories regarding the origin of the ore: volcanogenic–sedimentary and hydrothermal–metasomatic. The hydrothermal–sedimentary theory remains the prevailing hypothesis, but there are many indications that epigenetic hydrothermal–metasomatic and dynamic metamorphic processes have contributed to the formation of the deposit. These include the appearance of sulfide–quartz and quartz–carbonate–sulfide veins and vein zones in fine-grained “layered” ores, with large crystalline sphalerite and galena; multiple signs of ore recrystallization, including the formation of pyrite porphyroblasts and arsenopyrite metacrystals; and the formation of solid pyrrhotite and pyrrhotite–magnetite ores with a lenticular-striped, gneissic structure. These observations suggest that different processes, both hydrothermal–sedimentary and metamorphogenetic–metasomatic, were involved in the formation of the Ozernoe deposit. In other words, primary hydrothermal–sedimentary ores were redeposited by late hydrothermal solutions. Nevertheless, many issues concerning the genesis of the Ozernoe deposit remain unresolved.
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Han, Shili, Sheng Wang, Xianzhe Duan, M. Santosh, Sai Li, Haoran Sun, Zhenping Tang, et al. "Metallogenic Material Source and Genesis of the Jilinbaolige Pb-Zn-Ag Deposit, the Great Xing’an Range, China: Constraints from Mineralogical, S Isotopic, and Pb Isotopic Studies of Sulfide Ores." Minerals 12, no. 12 (November 27, 2022): 1512. http://dx.doi.org/10.3390/min12121512.
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The Jilinbaolige Pb-Zn-Ag polymetallic deposit is located in the eastern part of Inner Mongolia and in the central-southern part of the Great Xing’an Range, in which several large-sized Pb-Zn-Ag deposits have been found. The Jilinbaolige deposit, which occurs mainly at the contact zone between Yanshanian granite intrusion and sedimentary strata, shows strong NE-to-NNE structural control. The deposit includes three ore-forming stages: (1) the arsenopyrite–pyrite–chalcopyrite–sphalerite stage, (2) the galena–sphalerite–quartz stage, and (3) the pyrite–calcite–quartz stage. In this study, we present a systematic study on the mineralogical and geochemical characteristics (including major elements, S isotopes, and Pb isotopes) of the main sulfide ore minerals in the Jilinbaolige Pb-Zn-Ag deposit in order to evaluate the metallogenic environment, ore-forming material source, and genesis of this polymetallic deposit. The sulfide typomorphic characteristics, ore fabric, and thermometry suggest that the genesis of sulfides in the deposit is closely related to magmatic-hydrothermal activity. The early stage of mineralization might have evolved from a high-temperature hydrothermal environment. The sulfur isotopic results show that the δ34S values in the Jilinbaolige deposit range from 2.3‰ to 6.1‰, with an average value of 3.98‰, indicating that the sulfur originated from magmas with both mantle and crustal components. The Pb isotopic compositions (206Pb/204Pb = 18.214–18.330, 207Pb/204Pb = 15.478–15.615, 208Pb/204Pb = 37.957–38.292, μ = 9.24–9.50, ω = 34.49–36.49) of the sulfide ores suggest that that the lead is of crust-mantle mixed origin. The comparison between the S and Pb isotopic compositions of the Jilinbaolige deposit and the polymetallic deposits from the central-southern parts of the Great Xing’an Range suggests that these deposits have a similar metallogenic source, which is closely related to the Yanshanian granite and medium-temperature hydrothermal fluids. These ore-bearing hydrothermal fluids that evolved from deep magmatic sources migrated along the contact and fracture zones and during the subsequent gradual decrease in temperature, and the metallogenic components were deposited in the relatively open fracture and fissure space. Our results provide insights for further mineral prospecting in the south-central part of the Great Xing’an Range.
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Chubenko, Eugene, Alexey Klyshko, Vitaly Bondarenko, Marco Balucani, Anatoly I. Belous, and Victor Malyshev. "ZnO Films and Crystals on Bulk Silicon and SOI Wafers: Formation, Properties and Applications." Advanced Materials Research 276 (July 2011): 3–19. http://dx.doi.org/10.4028/www.scientific.net/amr.276.3.
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In present work the investigation of the electrochemical and chemical hydrothermal deposition processes of ZnO on silicon is presented. The influence of the electrochemical process parameters on the characteristics and morphology of the ZnO deposits is analyzed. Electrochemical deposition from non aqueous DMSO solutions on porous silicon buffer layer is also discussed. The details of the chemical hydrothermal deposition from the nitrate bath of high-quality ZnO crystals on silicon substrate are presented. It was shown that morphology and size of synthesized ZnO crystals depends on the temperature of the deposition bath. Differences between photoluminescence of electrochemically deposited ZnO thin films and hydrothermally synthesized crystals are shown. Electrochemically deposited ZnO films demonstrate defect-caused luminescence and hydrothermally grown ZnO crystals shows intensive exciton luminescence band in UV region. Hydrothermal deposition of high-quality ZnO crystals on the surface of electrochemically deposited ZnO seed layer with porous silicon buffer improves photoluminescence properties of the structure which is useful for optoelectronics applications. Possible applications of ZnO as gas sensors and photovoltaic devices are considered. Aspects of ZnO electrochemical deposition on bulk silicon and silicon-on-isolator wafers for integration purposes are discussed.
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Zhu, Bin, Hongfu Zhang, M. Santosh, Benxun Su, Pengfei Zhang, Chunming Han, and Yongsheng He. "Iron Isotopes Constrain the Metal Sources of Skarn Deposits: A Case Study from the Han-Xing Fe Deposit, China." Minerals 10, no. 11 (October 26, 2020): 951. http://dx.doi.org/10.3390/min10110951.
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Magmatic fluids and leaching of rocks are regarded as the two sources of magmatic hydrothermal deposits, but their relative contributions to the metals in the deposits are still unclear. In this study, we combine major elements and Fe isotopes in two sets of rocks from the Han-Xing iron skarn deposit in China to constrain the iron sources. The positive correlation between the δ56Fe and ∑Fe2O3/TiO2 of altered diorites (∑Fe2O3 refers to the total iron) demonstrates that heavy Fe isotopes are preferentially leached from diorites during hydrothermal alteration. However, except for the pyrite, all the rocks and minerals formed in the skarn deposit are enriched in the light Fe isotope relative to the fresh/less altered diorites. Therefore, besides the leaching of rocks, the Fe isotopically light magmatic fluid also provides a large quantity of iron for this deposit. Based on the mass balance calculation, we conclude that iron from magmatic fluid is almost 2.6 times as large as that from the leaching of rocks. This is the first study to estimate the relative proportions of iron sources for Fe deposits by using Fe isotopes. Here, we propose that the high δ56Fe of magmatic intrusions combining the positive correlation between their ∑Fe2O3/TiO2 and δ56Fe could be taken as a fingerprint of exsolution or interaction with magmatic fluids, which contributes to the exploration of magmatic hydrothermal ore deposits.
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Meng, Wuyi, Jiajun Liu, Huanhuan Wu, Zhen Zhang, Weidong Tang, Yongbao Gao, Liyong Wei, Bin Jia, Xin Zheng, and Ningbo Liu. "Metallogenic Mechanism of Carlin-Type Gold Deposit in Zhen’an-Xunyang Basin, in the South Qinling of China: Constraints of In Situ Trace Elements and S Isotopes from Newly Discovered Wangzhuang Gold Deposit." Minerals 13, no. 11 (November 20, 2023): 1459. http://dx.doi.org/10.3390/min13111459.
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The Zhen’an-Xunyang Basin is a late Paleozoic rifted basin with a series of Au-Hg-Sb deposits that have been found, mostly along the Nanyangshan fault. Recently discovered large- and medium-sized gold deposits such as the Xiaohe and Wangzhuang deposits exhibit typical characteristics of Carlin-type gold deposits. Therefore, it is imperative to select a typical deposit for an in-depth study of its metallogenic mechanism to support future prospecting efforts targeting the Carlin-type gold deposits within the area. Based on detailed field investigation and microphotographic observation, four ore-forming stages are identified: I, low-sulfide quartz stage, characterized by euhedral, subhedral pyrite, and fine veins of quartz injected parallel to the strata; II, arsenopyrite–arsenian pyrite–quartz stage, the main mineralization stage characterized by strongly silicified zones of reticulated quartz, disseminated arsenopyrite, fine-grained pyrite; III, low-sulfide quartz stage, characterized by large quartz veins cutting through the ore body or fine veins of quartz; Ⅳ, carbonate–quartz stage, characterized by the appearance of a large number of calcite veins. In situ analysis of trace elements and S isotopes of typical metal sulfides was carried out. The results show significant variations in the trace element compositions of metal sulfides in different stages, among which the main mineralization stage differs notably from those of the Au- and As-low surrounding strata. In situ S isotope analysis reveals δ34S values ranging from 15.78‰ to 28.71‰ for stage I metal sulfides, 5.52‰ to 11.22‰ for stage II, and 0.3‰ to 5.25‰ for stage III, respectively, revealing a gradual decrease in S isotopic values from the pre-mineralization stage to post-mineralization stage, similar to those observed in the Xiaohe gold deposit. These features indicate a distinct injection of relatively low 34S hydrothermal fluids during the mineralization process. The element anomalies of the 1:50,000 stream sediment in the region revealed ore-forming element zonation changing in W→Au (W)→Hg, Sb (Au) anomalies from west to east, manifested by the discovery of tungsten, gold, and mercury–antimony deposits in the area. Moreover, conspicuous Cr-Ni-Ti-Co-Mo anomalies were observed on the western side of the Wangzhuang and Xiaohe gold deposits, indicating a potential concealed pluton related to these deposits. These lines of evidence point to a magmatic–hydrothermal origin for the Carlin-type gold deposits in this area. Furthermore, hydrothermal tungsten deposits, Carlin-type gold deposits, and low-temperature hydrothermal mercury–antimony deposits in this region are probably controlled by the same magma–hydrothermal system.
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Zheng, Jiahao, Bin Chen, Shuaijie Liu, and Chuang Bao. "A TRIASSIC OROGENIC GOLD MINERALIZATION EVENT IN THE PALEOPROTEROZOIC METAMORPHIC ROCKS: EVIDENCE FROM TWO TYPES OF RUTILE IN THE BAIYUN GOLD DEPOSIT, LIAODONG PENINSULA, NORTH CHINA CRATON." Economic Geology 117, no. 7 (November 1, 2022): 1657–73. http://dx.doi.org/10.5382/econgeo.4945.
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Abstract Rutile grains often occur in different types of gold deposits, and their U-Pb ages have been widely used to determine the formation time of gold mineralization. However, the origin of rutile grains in the gold deposits remains controversial. In this paper, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of U-Pb ages and trace elements on rutile grains were applied to investigate the metamorphic and hydrothermal processes of the Baiyun gold deposit (70 t Au, avg grade: 3 g/t) in the Liaodong Peninsula in the northeastern part of the North China craton. Rutile grains in the hydrothermal altered gold schist from the Baiyun deposit yielded two group ages of 1924 ± 18 and 237.0 ± 1.8 Ma, respectively. Combined with our systematic U-Pb zircon geochronological results of the ore-hosting schists and post-ore dikes, we suggest these rutile ages record a Paleoproterozoic metamorphic event and a Triassic hydrothermal gold mineralization event, respectively. The metamorphic and hydrothermal rutile grains have no obvious textural differences, but they show distinct trace element contents of Zr, W, Nb, and Ta. Combined with previous published data, we propose that high W (>1,000 ppm) and low Zr (<200 ppm) contents in rutile can be used to distinguish hydrothermal rutile from metamorphic and magmatic rutile. The newly identified ca. 237 Ma hydrothermal event is much older than the ca. 227 to 210 Ma Triassic magmatic rocks in the region, which precludes a temporal and genetic link between the Baiyun gold mineralization and the regional Mesozoic magmatism. Rather, the ca. 237 Ma gold mineralization may be associated with the Triassic orogenic metamorphism, and Baiyun is an orogenic gold deposit. The Triassic gold deposits in the northern margin of the North China craton formed by orogenesis between the Siberian craton and the North China craton. After a hiatus, the large-scale gold deposits formed during the Early Cretaceous in the North China craton due to a westward subduction of the paleo-Pacific plate beneath the craton since the Early Jurassic. Our study highlights that rutile in gold deposits may be inherited from the host rocks and/or formed by hydrothermal fluids. Distinguishing between these two different rutile generations requires a combination of in situ age dating and trace element geochemistry in petrogenetic context.
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Groves, David I., Liang Zhang, and M. Santosh. "Subduction, mantle metasomatism, and gold: A dynamic and genetic conjunction." GSA Bulletin 132, no. 7-8 (November 4, 2019): 1419–26. http://dx.doi.org/10.1130/b35379.1.
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Abstract Global gold deposit classes are enigmatic in relation to first-order tectonic scale, leading to controversial genetic models and exploration strategies. Traditionally, hydrothermal gold deposits that formed through transport and deposition from auriferous ore fluids are grouped into specific deposit types such as porphyry, skarn, high- and low-sulfidation–type epithermal, gold-rich volcanogenic massive sulfide (VMS), Carlin-type, orogenic, and iron-oxide copper-gold (IOCG), and intrusion-related gold deposits (IRGDs). District-scale mineral system approaches propose interrelated groups such as porphyry Cu-Au, skarn Cu-Au-Ag, and high-sulfidation Au-Ag. In this study, the temporal evolution of subduction-related processes in convergent margins was evaluated to propose a continuum of genetic models that unify the various types of gold deposits. At the tectonic scale of mineral systems, all hydrothermal gold deposits are interrelated in that they formed progressively during the evolution of direct or indirect subduction-related processes along convergent margins. Porphyry-related systems formed initially from magmatic-hydrothermal fluids related to melting of fertile mantle to initiate calc-alkaline to high-K felsic magmatism in volcanic arcs directly related to subduction. Formation of gold-rich VMS systems was related to hydrothermal circulation driven by magmatic activity during rifting of oceanic arcs. Orogenic gold deposits formed largely through fluids derived from devolatilization of the downgoing slab and overlying sediment wedge during late transpression in the orogenic cycle. Carlin-type deposits, IRGDs, and some continental-arc porphyry systems formed during the early stages of orogenic collapse via fluids directly or indirectly related to hybrid magmatism from melting of lithosphere that was metasomatized and gold-fertilized by earlier fluid release from subduction zones near margins of continental blocks. The IOCGs were formed during postorogenic asthenosphere upwelling beneath such subduction-related metasomatized and fertilized lithospheric blocks via fluid release and explosive emplacement of volatile-rich melts. Thus, importantly, subduction is clearly recognized as the key unifying dynamic factor in gold metallogenesis, with subduction-related fluids or melts providing the critical ore components for a wide variety of gold-rich deposit types.
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Zarasvandi, Alireza, Mohsen Rezaei, Martiya Sadeghi, Houshang Pourkaseb, and Masoume Sepahvand. "Rare-earth element distribution and genesis of manganese ores associated with Tethyan ophiolites, Iran: A review." Mineralogical Magazine 80, no. 1 (February 2016): 127–42. http://dx.doi.org/10.1180/minmag.2016.080.054.
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AbstractThe Zagros orogenic and metallogenic belt is characterized by the widespread occurrence of manganese and ferromanganese deposits. These deposits are spatially associated with radiolarian cherts and basaltic rocks, which cap the ophiolite sequences. The present work provides a review on the rare-earth element (REE) geochemistry coupled with major- and trace-element geochemical characteristics of the Nasirabad and Abadeh Tashk manganese deposits (associated with the Neyriz ophiolite), and Sorkhvand manganese deposit (associated with the Kermanshah ophiolite). These data are used to gain an insight into the primary ore-forming processes that control the deposition of manganese ores. All of the selected manganese deposits have consistently high Ba contents and low concentrations of trace elements (Co, Cu and Ni) with high Mn/Fe ratios typical of hydrothermal activity. A relatively low REE abundance, Lan/Ndn ratios (>3), and position on a Lan/Cen vs. Al2O3/(Al2O3 + Fe2O3) discrimination plot indicate a distal hydrothermal source for almost all of the selected manganese deposits. Most of the deposits are characterized by Ceanom < –0.1 which reflects the prevailing oxidative conditions during the deposition of manganese ores. Importantly, this is consistent with the occurrence of non-sulfide oxic Mn mineralization in all the manganese deposits of the Zagros orogeny. The comparison of the Sorkhvand, Abadeh Tashk and Nasirabad manganese deposits with other manganese deposits elsewhere in the world indicates that major- and trace-element characteristics, as well as the REE composition of the Zagros manganese deposits are analogous to those typical of hydrothermal deposits.
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Xia, Guoti, Jianbo Yang, Ligang Fan, and Chaoyong Wang. "A Study on The Tectonic Control and Metallogenic Regularity of The Sanjiang Sanjiang Metallogenic Belt Cobalt Deposit in Yunnan Province." Highlights in Science, Engineering and Technology 67 (September 21, 2023): 341–45. http://dx.doi.org/10.54097/hset.v67i.12058.
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The Sanjiang region of Yunnan is rich in minerals, especially known for gold, copper, lead zinc, and iron ore deposits. There are many genetic types of ore deposits, and most of the ore deposits (points) and anomalies are controlled by the northwest north-south structural belt. The regional tectonic activity is strong and the metallogenic conditions are superior. In this paper, the structural ore-controlling effect and metallogenic regularity of Sanjiang Metallogenic Belt cobalt deposit in Yunnan Province are further studied. The mineralization of the ore belt is most closely related to the Caledonian submarine hydrothermal sedimentation, and after mineralization, it was obviously transformed by Indosinian metamorphism and hydrothermal superposition. Some scholars have carried out relevant research on the geological and geochemical characteristics and genesis of the deposit, and think that the deposit is stratabound-reformed, jet sedimentary, hydrothermal sedimentary-tectonic reformed, etc. However, the chemical properties of ductile rocks are inactive and the permeability is poor, which makes the ore-forming fluid difficult to lose, which is beneficial to the full water-rock reaction between minerals in hydrothermal solution and surrounding rocks flowing through carbonate rocks, resulting in a large number of minerals precipitation and enrichment. When the soft and hard rocks alternate with each other, it is beneficial to form bedding detachment structure to become ore storage space, and it is also beneficial to the precipitation of minerals along the chemical interface and the enrichment of minerals.
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Leonova, L. V., A. A. Galeev, and A. A. Galeev. "Microfossils in bottom-hydrothermal sediments of the Saf'yanovskoe Cu-Zn deposit (Middle Urals)." LITHOSPHERE (Russia) 22, no. 3 (July 2, 2022): 376–90. http://dx.doi.org/10.24930/1681-9004-2022-22-3-376-390.
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Research subject. Framboidal pyrites and sulfide micro-concretions in carbonaceous-siliceous and ore rocks of the Safyanovskoye deposit (Middle Urals). Aim. To identify the signs of vital activity of microbial communities in bottomhydrothermal deposits using the example of the Safyanovskoye sulfide deposit. The methods. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Results. TThe analyzed ore and carbonaceous-siliceous rock samples showed the presence of mineralized silicon dioxide films covering framboidal pyrites. Micro-concretions were found to consist of microfossils of filamentous organisms and framboids. Pyrite samples included the remains of tubular casts of sulfidized vestimentifera and polychaetes, associated with framboids. The possibility of using fossilized remains of microbial communities for distinguishing bottom-hydrothermal facies among pyrite deposits was confirmed. Conclusions. Hydrothermal-sedimentary deposits are characterized by the traces of specific microbial communities, since prokaryotic organisms were pioneers in hydrothermal oases. Their long active existence created a basis for the second trophic link, i.e. filter feeding macrofauna and endosymbiotrophs. These organisms, in turn, formed another level in the food chain of the trophic pyramid. It is believed that micro-concretions and framboidal pyrites are indicators of the vital activity of microbial communities.
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Li, Gen, Guicong Fang, Zuohai Feng, Cheng Xu, Zhennan Huang, and Chunzeng Wang. "Genetic Relationship between Granite and Fluorite Mineralization in the Shuanghuajiang Fluorite Deposit, Northern Guangxi, South China: Evidence from Geochronology, REE, and Fluid Geochemistry." Minerals 12, no. 9 (August 30, 2022): 1102. http://dx.doi.org/10.3390/min12091102.
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Hydrothermal vein-type fluorite deposits are the most important metallogenic type of fluorite deposits in South China, most of which are closely related to granitoid in space; however, the genetic relationship between granitoid and fluorite mineralization remains controversial. The Shuanghuajiang fluorite deposit in northern Guangxi of South China is a typical vein-type fluorite deposit hosted in a granite pluton, with the orebodies occurring within brittle faults. Zircon U-Pb dating of the hosting Xiangcaoping granite yields an emplacement age of 228.04 ± 0.76 Ma (MSWD = 0.072). Fluorite Sm-Nd dating yields an isochron age of 185 ± 18 Ma. The new age data indicate that the fluorite deposit was precipitated significantly later than the emplacement of the hosting Xiangcaoping granite pluton. The fluorite and granite exhibit similar rare earth element (REE) patterns with negative Eu anomalies, suggesting that fluorine (F) was derived from the granite. The fluorite fluid inclusions show a homogeneous temperature mainly ranging between 165 °C and 180 °C. Salinity is typically less than 1% NaCl eqv, while the δ18OV-SMOW and δDV-SMOW values are between −5.2‰–−6.1‰ and −17.35‰–−23.9‰, respectively. These indicate that the ore-forming fluids were a NaCl-H2O system with medium-low temperature and low salinity, which is typical for meteoric water. Given the combined evidence of geochronology, REE, and fluid geochemistry, the mineralization of the Shuanghuajiang fluorite deposit is unrelated to magmatic-hydrothermal activity but achieved via hydrothermal circulation and leaching mechanisms. Our study presents a genetic relationship between the fluorite deposit and granitoids based on an example of northern Guangxi, providing a better understanding of the genesis of hydrothermal vein-type fluorite deposits in granitoids outcropping areas.
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Courtney-Davies, Liam, Cristiana L. Ciobanu, Simon R. Tapster, Nigel J. Cook, Kathy Ehrig, James L. Crowley, Max R. Verdugo-Ihl, Benjamin P. Wade, and Daniel J. Condon. "OPENING THE MAGMATIC-HYDROTHERMAL WINDOW: HIGH-PRECISION U-Pb GEOCHRONOLOGY OF THE MESOPROTEROZOIC OLYMPIC DAM Cu-U-Au-Ag DEPOSIT, SOUTH AUSTRALIA." Economic Geology 115, no. 8 (August 27, 2020): 1855–70. http://dx.doi.org/10.5382/econgeo.4772.
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Abstract Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic. Unlike accessory minerals routinely used to track hydrothermal mineralization, iron oxides are dominant components of IOCG systems and are therefore pivotal to understanding deposit evolution. The presence of ubiquitous, magmatic-hydrothermal U-(Pb)-W-Sn-Mo–bearing zoned hematite resolves a range of geochronological issues concerning formation of the ~1.6 Ga Olympic Dam IOCG deposit, South Australia, at up to ~0.05% precision (207Pb/206Pb weighted mean; 2σ) using isotope dilution-thermal ionization mass spectrometry (ID-TIMS). Coupled with chemical abrasion-ID-TIMS zircon dates from host granite and volcanic rocks within and enclosing the ore-body, a confident magmatic-hydrothermal chronology is defined. The youngest zircon date from the granite intrusion hosting Olympic Dam indicates magmatism was occurring up until 1593.28 ± 0.26 Ma. The orebody was principally formed during a major mineralizing event following granite uplift and during cupola collapse, whereby the hematite with the oldest age is recorded in the outer shell of the deposit at 1591.27 ± 0.89 Ma, ~2 m.y. later than the youngest documented magmatic zircon. Hematite dates captured throughout major lithologies, different ore zones, and the ~2-km vertical extent of the deposit support ~2 m.y. of hydrothermal activity. New age constraints on the spatial-temporal evolution of the formation of Olympic Dam are considered with respect to a mantle to crustal continuum model. Cyclical tapping of magma reservoirs to maintain crystal mushes for extended time periods and incremental building of batholiths on the million-year scale prior to main mineralization pulses can explain the ~2-m.y. temporal window temporal window inferred from the data. Despite the challenge of reconciling such an extended window with contemporary models for porphyry deposits (≤1 m.y.), formation of Proterozoic ore deposits has been addressed at high-precision and supports the case that giant IOCG deposits may form over millions of years.
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Yildiz, A., and M. Kuscu. "Origin of the Basoren (Kutahya, W Turkey) bentonite deposits." Clay Minerals 39, no. 2 (June 2004): 219–31. http://dx.doi.org/10.1180/0009855043920132.
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AbstractBentonite deposits in Basoren Kutahya, West Anatolia, Turkey formed from alteration of perlite and pyroclastic rocks of Pliocene age. The distribution of bentonite deposits along faults in the study area indicates that the alteration solutions were hydrothermal. Although lateral zonation is observed in bentonite deposits in some regions (i.e. Demirli, Akyokus, Seklice- Sarıokuz, etc.), alteration zones are extremely irregular in the Cayırlık bentonite deposit.X-ray diffraction studies have shown that Basoren bentonites contain dioctahedral Ca-smectite.The Greene-Kelly test (Li-saturation and heating) showed that the Demirli and Akyokus bentonites consist of montmorillonite and that the Cayırlık bentonite consists of montmorillonite and/or beidellite. Spherulitic or hemispherical ‘crystals’ of opal-CT minerals formed from hydrothermal alteration of volcanic glass. The MgO, CaO and total Fe2O3 enrichment in bentonites, compared to parent rocks, is related to the chemical composition of hydrothermal solutions that passed through the ophiolitic rocks such as serpentinite.
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Fontboté, Lluís, Kalin Kouzmanov, Massimo Chiaradia, and Gleb S. Pokrovski. "Sulfide Minerals in Hydrothermal Deposits." Elements 13, no. 2 (April 2017): 97–103. http://dx.doi.org/10.2113/gselements.13.2.97.
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Lykakis, N., and S. P. Kilias. "EPITHERMAL MANGANESE MINERALIZATION, KIMOLOS ISLAND, SOUTH AEGEAN VOLCANIC ARC, GREECE." Bulletin of the Geological Society of Greece 43, no. 5 (July 31, 2017): 2646. http://dx.doi.org/10.12681/bgsg.11672.
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Manganese mineralization is hosted by a marine monomictic, lithic volcaniclastic breccia, possibly an andesitic in situ hyaloclastite, and shallow-marine or subaerial epiclastic conglomerates, in the Korakies area, NE Kimolos, active south Aegean volcanic arc. Old mine workings (in the form of rubble, adit and shaft), and abandoned rail and ship loading facilities, exist in the area. Mineralization occurs as a quartz/chalcedony vein system filling extensional NNE-SSW–trending faults and fractures, of Pliocene age. Maximum vein width reaches 5 m; length may extend to 250 m. The ore shares strong textural analogies with volcanic-hosted epithermal-style deposits, i.e. crustiform banding, vugs, hydrothermal breccias, cockade and comb textures. Vein wall rocks are hydrothermally altered to quartz-adularia±illite, chlorite and barite. Pyrolusite, hollandite, cryptomelane, and coronadite are the main ore minerals, with quartz, chalcedony, jasper and barite gangue. Ore samples contain up to 25.8 % MnO2, 14.7 % FeOTOT, 2860 ppm Zn, 1132 ppm Pb and 136 ppm Cu; Mn and Zn show mutual positive correlation (r2=0.61). Trace element enrichment (i.e. Zn, Pb, and Cu) may suggest a proximal base metal sulfide mineralization. Concentrations of 4.3 % Na, 0.09 % Mg and barite presence may suggest genetic involvement of sea water. The mineralization studied is similar to volcanic-hosted low-sulfidation epithermal ore deposits deposited from neutral pH fluids. This is a rare example of a vein-type epithermal-style hydrothermal manganese deposit formed in a marine environment.
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Yan, Yu Tong, Sheng Rong Li, Bao Jian Jia, Na Zhang, Liang Jiang, and Li Na Yan. "A New Method to Quantify Morphology of Pyrite, and Application to Magmatic-Hydrothermal Gold Deposits in Jiaodong Peninsula, China." Advanced Materials Research 446-449 (January 2012): 2015–27. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2015.
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Morphology of pyrite has been an important indicator of conditions in the ore-forming environment. This study establishes a new pyrite morphology quantification method to characterize different types of magmatic-hydrothermal gold deposits, applying this method to the Linglong, Sanshandao and Xiadian magmatic-hydrothermal gold deposits in Jiaodong peninsula, China. We used K curve and coefficient Y to characterize the Linglong type and Jiaojia type gold deposits. It showed that Linglong type and Jiaojia type gold deposits had different K curves and coefficient Y characteristics. The results showed that this method was proper in magmatic-hydrothermal gold deposits. It is concluded that the K curve and the coefficient Y are important parameters to characterize pyrite morphology in magmatic-hydrothermal gold deposits. This quantification method was called “K curve method”.
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Zoben’ko, O. A., V. M. Okrugin, I. I. Chernev, E. Yu Plutakhina, D. A. Yablokova, and E. V. Kartasheva. "CHEMOGENIC SEDIMENTS OF MUTNOVSKY GEOTHERMAL COMPLEX (SOUTH KAMCHATKA)." Bulletin of Kamchatka Regional Association «Educational-Scientific Center». Earth Sciences, no. 3(51) (2021): 66–76. http://dx.doi.org/10.31431/1816-5524-2022-3-51-66-76.
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By studying the processes taking place at the operating geothermal stations it is possible to model and understand some features of formation of minerals of geothermal origin, processes of transfer by hydrothermal solutions and concentration of some metals by analogy with the ore-forming processes at the formed deposits. During the release of steam-water mixture and outpouring of water from the wells silica gel is deposited, a number of elements (including noble metals) migrate and accumulate in the sediments. A great role during exploitation of wells, operation of turbines, separators and other structural elements of geothermal stations is played by the chemical composition of the coolant. Because of its high mineralization deposition on various units and parts of equipment occurs, what may complicate the operation of a geothermal plant. We describe the composition of chemogenic deposits on various technological elements of the Mutnovskaya geothermal power plant. Data on sediments sampled in boreholes, on turbine blades and separator are presented. We have revealed a wide variety of such deposits, both oxide compounds and ore phases (from magnetite, chalcopyrite, minerals of faint ore group to native gold, tellurides, selenides and sulfides of gold and silver). We suppose that the processes currently taking place at the Mutnovskoye steam hydrothermal field are similar to the hydrothermal processes that contributed to the formation of vein zones of the gold-silver-polymetallic deposit of the same name.
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Zoben’ko, O. A., V. M. Okrugin, I. I. Chernev, E. Yu Plutakhina, D. A. Yablokova, and E. V. Kartasheva. "CHEMOGENIC SEDIMENTS OF MUTNOVSKY GEOTHERMAL COMPLEX (SOUTH KAMCHATKA)." Bulletin of Kamchatka Regional Association «Educational-Scientific Center». Earth Sciences, no. 3(51) (2021): 66–76. http://dx.doi.org/10.31431/1816-5524-2022-3-51-66-76.
Full textAbstract:
By studying the processes taking place at the operating geothermal stations it is possible to model and understand some features of formation of minerals of geothermal origin, processes of transfer by hydrothermal solutions and concentration of some metals by analogy with the ore-forming processes at the formed deposits. During the release of steam-water mixture and outpouring of water from the wells silica gel is deposited, a number of elements (including noble metals) migrate and accumulate in the sediments. A great role during exploitation of wells, operation of turbines, separators and other structural elements of geothermal stations is played by the chemical composition of the coolant. Because of its high mineralization deposition on various units and parts of equipment occurs, what may complicate the operation of a geothermal plant. We describe the composition of chemogenic deposits on various technological elements of the Mutnovskaya geothermal power plant. Data on sediments sampled in boreholes, on turbine blades and separator are presented. We have revealed a wide variety of such deposits, both oxide compounds and ore phases (from magnetite, chalcopyrite, minerals of faint ore group to native gold, tellurides, selenides and sulfides of gold and silver). We suppose that the processes currently taking place at the Mutnovskoye steam hydrothermal field are similar to the hydrothermal processes that contributed to the formation of vein zones of the gold-silver-polymetallic deposit of the same name.
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Dolgushin, S. S., and A. P. Dolgushin. "ROLE OF ORE MAGMAS IN THE FORMATION OF DEPOSITS." Geology and mineral resources of Siberia, no. 2 (2021): 84–91. http://dx.doi.org/10.20403/2078-0575-2021-2-84-91.
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Notions are substantiated that for a certain group of so-called hydrothermal deposits, not regular lowconcentration hydrothermal solutions, including their more concentrated derivatives, colloids, are not of decisive importance in their formation, but highly concentrated magmatic systems – ore magmas forming deposits by intrusive way, at a time when hydrothermal (including gas-hydrothermal) solutions coexisting with them, being more mobile and chemically active, produce only metasomatic changes in the host rocks and wallrock dissemination, masking the magmatic nature of deposits.
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Rodriguez-Mustafa, Maria A., Adam C. Simon, Irene del Real, John F. H. Thompson, Laura D. Bilenker, Fernando Barra, Ilya Bindeman, and David Cadwell. "A Continuum from Iron Oxide Copper-Gold to Iron Oxide-Apatite Deposits: Evidence from Fe and O Stable Isotopes and Trace Element Chemistry of Magnetite." Economic Geology 115, no. 7 (November 1, 2020): 1443–59. http://dx.doi.org/10.5382/econgeo.4752.
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Abstract Iron oxide copper-gold (IOCG) and iron oxide-apatite (IOA) deposits are major sources of Fe, Cu, and Au. Magnetite is the modally dominant and commodity mineral in IOA deposits, whereas magnetite and hematite are predominant in IOCG deposits, with copper sulfides being the primary commodity minerals. It is generally accepted that IOCG deposits formed by hydrothermal processes, but there is a lack of consensus for the source of the ore fluid(s). There are multiple competing hypotheses for the formation of IOA deposits, with models that range from purely magmatic to purely hydrothermal. In the Chilean iron belt, the spatial and temporal association of IOCG and IOA deposits has led to the hypothesis that IOA and IOCG deposits are genetically connected, where S-Cu-Au–poor magnetite-dominated IOA deposits represent the stratigraphically deeper levels of S-Cu-Au–rich magnetite- and hematite-dominated IOCG deposits. Here we report minor element and Fe and O stable isotope abundances for magnetite and H stable isotope abundances for actinolite from the Candelaria IOCG deposit and Quince IOA prospect in the Chilean iron belt. Backscattered electron imaging reveals textures of igneous and magmatic-hydrothermal affinities and the exsolution of Mn-rich ilmenite from magnetite in Quince and deep levels of Candelaria (>500 m below the bottom of the open pit). Trace element concentrations in magnetite systematically increase with depth in both deposits and decrease from core to rim within magnetite grains in shallow samples from Candelaria. These results are consistent with a cooling trend for magnetite growth from deep to shallow levels in both systems. Iron isotope compositions of magnetite range from δ56Fe values of 0.11 ± 0.07 to 0.16 ± 0.05‰ for Quince and between 0.16 ± 0.03 and 0.42 ± 0.04‰ for Candelaria. Oxygen isotope compositions of magnetite range from δ18O values of 2.65 ± 0.07 to 3.33 ± 0.07‰ for Quince and between 1.16 ± 0.07 and 7.80 ± 0.07‰ for Candelaria. For cogenetic actinolite, δD values range from –41.7 ± 2.10 to –39.0 ± 2.10‰ for Quince and from –93.9 ± 2.10 to –54.0 ± 2.10‰ for Candelaria, and δ18O values range between 5.89 ± 0.23 and 6.02 ± 0.23‰ for Quince and between 7.50 ± 0.23 and 7.69 ± 0.23‰ for Candelaria. The paired Fe and O isotope compositions of magnetite and the H isotope signature of actinolite fingerprint a magmatic source reservoir for ore fluids at Candelaria and Quince. Temperature estimates from O isotope thermometry and Fe# of actinolite (Fe# = [molar Fe]/([molar Fe] + [molar Mg])) are consistent with high-temperature mineralization (600°–860°C). The reintegrated composition of primary Ti-rich magnetite is consistent with igneous magnetite and supports magmatic conditions for the formation of magnetite in the Quince prospect and the deep portion of the Candelaria deposit. The trace element variations and zonation in magnetite from shallower levels of Candelaria are consistent with magnetite growth from a cooling magmatic-hydrothermal fluid. The combined chemical and textural data are consistent with a combined igneous and magmatic-hydrothermal origin for Quince and Candelaria, where the deeper portion of Candelaria corresponds to a transitional phase between the shallower IOCG deposit and a deeper IOA system analogous to the Quince IOA prospect, providing evidence for a continuum between both deposit types.
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Hintzen, Robin, Wolfgang Werner, Michael Hauck, Reiner Klemd, and Lennart A. Fischer. "Multistage fluorite mineralization in the southern Black Forest, Germany: evidence from rare earth element (REE) geochemistry." European Journal of Mineralogy 35, no. 3 (June 21, 2023): 403–26. http://dx.doi.org/10.5194/ejm-35-403-2023.
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Abstract. The Black Forest hosts a wide range of hydrothermal mineralization, including fluorite–barite vein deposits. In a detailed investigation of the Finstergrund and Tannenboden deposits in the Wieden mining district (southern Black Forest), the diversity, geochemical evolution and relative chronology of multistage fluorite precipitation is tracked on the basis of rare earth element (REE) geochemistry, geologic field relationships and crystal zoning. Geochemical discrimination and mathematical λ coefficients suggest a total of seven fluorite REE groups, at least three distinguishable post-Variscan fluid mobilization events and independent formation histories for the deposits despite their spatial proximity. Fluorite vein mineralization at the Finstergrund deposit evolved over three fluid generations, was derived from gneissic source aquifers and comprises five distinct fluorite REE groups: the first fluid generation is characterized by fluorite precipitation above 200 ∘C (“group III”), below 200 ∘C (“group I”) and after fractional crystallization (“group IV”); the second generation comprises remobilized fluorite (“group II”); and the third generation revealed fluorite precipitation by meteoric water mixing (“group V”). Fluorite vein formation at the Tannenboden deposit is associated with two distinct fluorite REE patterns derived from the same fluid generation: fluorite precipitation above 200 ∘C (“group VII”) and after cooling below 200 ∘C (“group VI”). Its fluid source aquifer lithology best matches migmatites contrary to previous models that suggest either gneissic or granitic aquifer rocks for fluorite vein precipitation in the Black Forest. The decoupled formation history between the deposits is tectonically controlled as suggested by a new genetic model for the Wieden mining district. The model argues for a change in the local fluid percolation network and the termination of hydrothermal activity at the Tannenboden deposit after the first fluid mobilization event. The geochemical evolution of multistage fluorite mineralization, as exemplified by the Tannenboden and Finstergrund deposits in combination with other fluorite mineralizations in the Black Forest, provides unique insights into the lithospheric origin and precipitation behaviour of fluorite by various fluid–rock interaction processes occurring in large hydrothermal systems. The local diversity of REE patterns emphasizes the need for detailed investigations of individual hydrothermal vein deposits.
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Morishita, Yuichi, Napoleon Q. Hammond, Kazunori Momii, Rimi Konagaya, Yuji Sano, Naoto Takahata, and Hirotomo Ueno. "Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence." Minerals 9, no. 7 (July 19, 2019): 447. http://dx.doi.org/10.3390/min9070447.
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“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.
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Damdinova, Ludmila, and Bulat Damdinov. "Tungsten Ores of the Dzhida W-Mo Ore Field (Southwestern Transbaikalia, Russia): Mineral Composition and Physical-Chemical Conditions of Formation." Minerals 11, no. 7 (July 5, 2021): 725. http://dx.doi.org/10.3390/min11070725.
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This article discusses the peculiarities of mineral composition and a fluid inclusions (FIs further in the text) study of the Kholtoson W and Inkur W deposits located within the Dzhida W-Mo ore field (Southwestern Transbaikalia, Russia). The Mo mineralization spatially coincides with the apical part of the Pervomaisky stock (Pervomaisky deposit), and the W mineralization forms numerous quartz veins in the western part of the ore field (Kholtoson vein deposit) and the stockwork in the central part (Inkur stockwork deposit). The ore mineral composition is similar at both deposits. Quartz is the main gangue mineral; there are also present muscovite, K-feldspar, and carbonates. The main ore mineral of both deposits is hubnerite. In addition to hubnerite, at both deposits, more than 20 mineral species were identified; they include sulfides (pyrite, chalcopyrite, galena, sphalerite, bornite, etc.), sulfosalts (tetrahedrite, aikinite, stannite, etc.), oxides (scheelite, cassiterite), and tellurides (hessite). The results of mineralogical and fluid inclusions studies allowed us to conclude that the Inkur W and the Kholtoson W deposits were formed by the same hydrothermal fluids, related to the same ore-forming system. For both deposits, the fluid inclusion homogenization temperatures varied within the range ~195–344 °C. The presence of cogenetic liquid- and vapor-dominated inclusions in the quartz from the ores of the Kholtoson deposit allowed us to estimate the true temperature range of mineral formation as 413–350 °C. Ore deposition occurred under similar physical-chemical conditions, differing only in pressures of mineral formation. The main factors of hubnerite deposition from hydrothermal fluids were decreases in temperature.
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Paudyal, Kabiraj. "Occurrences of mineral resources in Bandipur Gondrang area of Tanahun district, central Nepal, Lesser Himalaya." Journal of Science and Engineering 2 (January 30, 2014): 24–35. http://dx.doi.org/10.3126/jsce.v2i0.22484.
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A detailed geological investigation was carried out to assess the distribution of minerals and their geological control in Bandipur-Gondrang area of Tanahu district, a part of Lesser Himalaya in central Nepal. The area is found rich in both metallic and non-metallic mineral deposits. The main metallic minerals found are iron in Phalamdada and Labdi Khola, copper in Bhut Khola and poly-metallic deposits including suspected gold in Bhangeri Khola and Jaubari Khola-Bar Khola sections. A large deposit of inorganic carbon is found around the Gondrang-Watak area. Similarly, a good quality of green marble (metabasite) is found as decorative stone in Bagar Khola area and good quality of roofing stone in Bandipur area. In addition to these economic deposits other several sub economic to non-economic mineral are also located in the geological map of the area. Categorization of these mineral deposits is based on the probable reserve and laboratory analysis of related samples. Geological control of mineral deposits is considered to be the stratigraphic, structural, metamorphic and hydrothermal. Iron mineralization of the area is found stratigraphical control, copper deposits by magmatism of basic rocks (amphibolites), and poly-metallic deposits are related to the hydrothermal processes.
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Lopes, Adriana Araújo Castro, and Márcia Abrahão Moura. "The Tocantinzinho Paleoproterozoic Porphyry-Style Gold Deposit, Tapajós Mineral Province (Brazil): Geology, Petrology and Fluid Inclusion Evidence for Ore-Forming Processes." Minerals 9, no. 1 (January 5, 2019): 29. http://dx.doi.org/10.3390/min9010029.
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The Tocantinzinho gold deposit, located in the Tapajós Mineral Province, Amazonia, Brazil, is considered the largest gold deposit in the region. It is a stockwork-disseminated gold deposit, hosted in a 1982 ± 8 Ma hydrothermalized monzogranite of the Creporizão Intrusive Suite, with petrographic and geochemical characteristics of volcanic arc to post-collisional granites. Gold is mainly associated with phyllic alteration. Primary fluid inclusions trapped in the mineralization stages are H2O–NaCl and unsaturated and homogenize either to the vapor or to the liquid with Th(t) of 300–430 °C, salinity of 2–16 wt % NaCl eq. and density from 0.43 to 0.94 g/cm3. At these conditions, Au is expected to be transported as Au(HS)2− complexes and ore is deposited as the result of boiling in the first mineralizing stages and of mixing between magmatic fluid and meteoric water during the phyllic alteration. Compared with other deposits, Tocantinzinho has similarities with magmatic-hydrothermal oxidized calc-alkaline granite-related gold deposits classified as porphyry gold deposits but we classify as a porphyry-style gold deposit, as it lacks some characteristics of the Phanerozoic porphyry-type deposits. The results from this study can be used to elaborate and guide prospection models in Amazonia and in similar Proterozoic terrains.
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Jin, Xiao-Ye, Jian-Xin Zhao, Yue-Xing Feng, Albert H. Hofstra, Xiao-Dong Deng, Xin-Fu Zhao, and Jian-Wei Li. "CALCITE U-Pb DATING UNRAVELS THE AGE AND HYDROTHERMAL HISTORY OF THE GIANT SHUIYINDONG CARLIN-TYPE GOLD DEPOSIT IN THE GOLDEN TRIANGLE, SOUTH CHINA." Economic Geology 116, no. 6 (September 1, 2021): 1253–65. http://dx.doi.org/10.5382/econgeo.4870.
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Abstract The ages of Carlin-type gold deposits in the Golden Triangle of South China have long been questioned due to the general lack of minerals unequivocally linked to gold deposition that can be precisely dated using conventional radiogenic isotope techniques. Recent advances in U-Pb methods show that calcite can be used to constrain the ages of hydrothermal processes, but few studies have been applied to ore deposits. Herein, we show that this approach can be used to constrain the timing of hydrothermal activity that generated and overprinted the giant Shuiyindong Carlin-type gold deposit in the Golden Triangle. Three stages of calcite (Cal-1, Cal-2, and Cal-3) have been recognized in this deposit based on crosscutting relationships, cathodoluminescence colors, and chemical (U, Pb, and rare earth element [REE]) and isotope (C, O, Sr) compositions. Cal-1 is texturally associated with ore-stage jasperoid and disseminated Au-bearing arsenian pyrite in hydrothermally altered carbonate rocks, which suggests it is synmineralization. Cal-2 fills open spaces and has a distinct orange cathodoluminescence, suggesting that it precipitated during a second fluid pulse. Cal-1 and Cal-2 have similar carbonate rock-buffered chemical and isotopic compositions. Cal-3 occurs in veins that often contain realgar and/or orpiment and are chemically (low U, Pb, and REE) and isotopically (higher δ13C, lower δ18O and Sri values) distinct from Cal-1 and Cal-2, suggesting that it formed from a third fluid. U-Pb isotope analyses, by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for U-rich Cal-1 and Cal-2 and by LA-multicollector (MC)-ICP-MS for U-poor Cal-3, yield well-defined age constraints of 204.3 to 202.6, 191.9, and 139.3 to 137.1 Ma for Cal-1, Cal-2, and Cal-3, respectively. These new ages suggest that the Shuiyindong gold deposit formed in the late Triassic and was overprinted by hydrothermal events in the early Jurassic and early Cretaceous. Given the association of Cal-3 with orpiment and realgar, and previous geochronologic studies of several other major gold deposits in the Golden Triangle, we infer that the latest stage of calcite may be associated with an early Cretaceous regional gold metallogenic event. Combined with existing isotopic ages in the region, these new ages lead us to propose that Carlin-type gold deposits in the Golden Triangle formed during two metallogenic episodes in extensional settings, associated with the late Triassic Indochina orogeny and early Cretaceous paleo-Pacific plate subduction. This study shows that the calcite U-Pb method can be used to constrain the timing of Carlin-type gold deposits and successive hydrothermal events.
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Montanaro, Cristian, Shane Cronin, Bettina Scheu, Ben Kennedy, and Bradley Scott. "Complex crater fields formed by steam-driven eruptions: Lake Okaro, New Zealand." GSA Bulletin 132, no. 9-10 (January 22, 2020): 1914–30. http://dx.doi.org/10.1130/b35276.1.
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Abstract Steam-driven eruptions are caused by explosive vaporization of water within the pores and cracks of a host rock, mainly within geothermal or volcanic terrains. Ground or surface water can be heated and pressurized rapidly from below (phreatic explosions), or already hot and pressurized fluids in hydrothermal systems may decompress when host rocks or seals fail (hydrothermal eruptions). Deposit characteristics and crater morphology can be used in combination with knowledge of host-rock lithology to reconstruct the locus, dynamics, and possible triggers of these events. We investigated a complex field of >30 craters formed over three separate episodes of steam-driven eruptions at Lake Okaro within the Taupo volcanic zone, New Zealand. Fresh unaltered rock excavated from initially >70 m depths in the base of phase I breccia deposits showed that eruptions were deep, “bottom-up” explosions formed in the absence of a preexisting hydrothermal system. These phreatic explosions were likely triggered by sudden rise of magmatic fluids/gas to heat groundwater within an ignimbrite 70 m below the surface. Excavation of a linear set of craters and associated fracture development, along with continued heat input, caused posteruptive establishment of a large hydrothermal system within shallow, weakly compacted, and unconsolidated deposits, including the phase I breccia. After enough time for extensive hydrothermal alteration, erosion, and external sediment influx into the area, phase II occurred, possibly triggered by an earthquake or hydrological disruption to a geothermal system. Phase II produced a second network of craters into weakly compacted, altered, and pumice-rich tuff, as well as within deposits from phase I. Phase II breccias display vertical variation in lithology that reflects top-down excavation from shallow levels (10–20 m) to >70 m. After another hiatus, lake levels rose. Phase III hydrothermal explosions were later triggered by a sudden lake-level drop, excavating into deposits from previous eruptions. This case shows that once a hydrothermal system is established, repeated highly hazardous hydrothermal eruptions may follow that are as large as initial phreatic events.
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Gao, Bangfei, Minghua Dong, Hui Xie, Zhiliang Liu, Yihang Li, and Tong Zhou. "Discovery and Exploration of the Luming Porphyry Mo Deposit, Northeastern China: Implications for Regional Prospecting." Minerals 14, no. 7 (July 16, 2024): 718. http://dx.doi.org/10.3390/min14070718.
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Over the past two decades, significant deposit discoveries were made in Northeastern China, including the super-large Chalukou, Daheishan, and Luming porphyry Mo deposits. The discovery of the Luming deposit was accomplished through verification of stream sediment anomalies, with mineralization closely associated with early Jurassic monzogranite and granite porphyry. Previous studies primarily focused on the mineralization mechanisms of these deposits without adequately addressing the exploration methods and prospecting criteria. This study involved a comprehensive re-evaluation of geological observations, analysis of rock primary halo, gravity and magnetic surveys, and induced polarization surveys conducted during exploration campaigns at the Luming porphyry Mo deposit. The results suggest that hydrothermal breccias play a critical role in controlling the mineralization by forming a central low-grade core within the deposit while the Mo mineralization and hydrothermal alteration exhibit a donut-shaped distribution around it. The primary halo shows a distinct metal zonation moving from a central W-Bi-Mo-(Sb) to a peripheral Cu-Co-Ni and a distal Pb-Zn-Ag-In. The mineralization zone exhibits a low Bouguer gravity anomaly, negative magnetic anomaly, medium to low resistivity, and moderate to high chargeability, indicating the effectiveness of geophysical methods in defining the extent of the ore body. The Luming porphyry Mo deposit and distal skarn-epithermal Pb-Zn mineralization are parts of a porphyry-related magmatic-hydrothermal system. The results of this study offer valuable insights into the genesis of porphyry Mo deposits and their implications for prospecting in the forested region of Northeastern China.
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Sciuba, Marjorie, and Georges Beaudoin. "Texture and Trace Element Composition of Rutile in Orogenic Gold Deposits." Economic Geology 116, no. 8 (December 1, 2021): 1865–92. http://dx.doi.org/10.5382/econgeo.4857.
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Abstract Rutile from a wide range of orogenic gold deposits and districts, including representative world-class deposits, was investigated for its texture and trace element composition using scanning electron microscopy, electron probe microanalysis, and laser ablation-inductively coupled plasma-mass spectrometry. Deposits are hosted in various country rocks including felsic to ultramafic igneous rocks and sedimentary rocks, which were metamorphosed from lower greenschist to middle amphibolite facies and with ages of mineralization that range from Archean to Phanerozoic. Rutile presents a wide range of size, texture, and chemical zoning. Rutile is the dominant TiO2 polymorph in orogenic gold mineralization. Elemental plots and partial least square-discriminant analysis suggest that the composition of the country rocks exerts a strong control on concentrations of V, Nb, Ta, and Cr in rutile, whereas the metamorphic facies of the country rocks controls concentrations of V, Zr, Sc, U, rare earth elements, Y, Ca, Th, and Ba in rutile. The trace element composition of rutile in orogenic gold deposits can be distinguished from rutile in other deposit types and geologic settings. Elemental ratios Nb/V, Nb/Sb, and Sn/V differentiate the rutile trace element composition of orogenic gold deposits compared with those from other geologic settings and environments. A binary plot of Nb/V vs. W enables distinction of rutile in metamorphic-hydrothermal and hydrothermal deposits from rutile in magmatic-hydrothermal deposits and magmatic environments. The binary plot Nb/Sb vs. Sn/V distinguishes rutile in orogenic gold deposits from other geologic settings and environments. Results are used to establish geochemical criteria to constrain the source of rutile for indicator mineral surveys and potentially guide mineral exploration.
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North, Jon, and D. H. C. Wilton. "Origins of stratiform and stratabound Fe–Cu–Zn horizons in the Lower Proterozoic Moran Lake Group, Labrador Central Mineral Belt." Canadian Journal of Earth Sciences 29, no. 5 (May 1, 1992): 837–53. http://dx.doi.org/10.1139/e92-072.
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Zn, Cu, and Fe are concentrated as stratiform and stratabound sulphide-rich beds in the Lower Proterozoic Warren Creek Formation, Moran Lake Group, central Labrador. Upper Member sedimentary rocks have a hydrothermal-like Fe enrichment but a dominantly hydrogenous signature as indicated by high Al2O3 relative to SiO2, and high Al and Fe relative to Mn. The Upper Member shales and sulphide-rich beds were deposited as Fe-rich pelagic sediments. The paucity of Mn and abundance of Fe in typical shale samples and lack of Cu, Pb, and Zn fractionation in stratiform massive sulphide beds that contain up to 4702 ppm Zn, 533 ppm Cu, and 15 ppm Pb suggest that deposition occurred in restricted brine pools (i.e., Cu and Zn were precipitated rapidly and were not fractionated). Stratabound sphalerite mineralization containing > 3.7% Zn and 121 ppm Cu (but no Pb) was deposited in a porous lithology at the top of the Warren Creek Formation and represents a unique style of metal concentration.The stratiform deposits probably formed by advection of low-temperature connate waters in a situation typical of sediment-hosted exhalative mineralization (SEDEX). The potential for ore-grade metal concentration is apparently low because metal associations (Fe,Cu,Pb,Zn,Ba) are unlike those of sediment-hosted massive sulphide deposits, the sediments have a dominantly hydrogenous rather than hydrothermal signature, and the absolute grades of known occurrences are very low. The stratabound Zn deposit was probably formed by converting Zn-rich brines (≤ 200 °C) trapped during development of a hydrothermal convection system during a period of increased geothermal gradient. The potential for this type of occurrence in the Warren Creek area to reach economic grade is limited because the convection cells were shallow, ephemeral, and without the metal associations of sediment-hosted massive sulphide deposits.
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Shabaga, Brandi M., Mostafa Fayek, David Quirt, and Patrick Ledru. "Sources of sulphur for the Proterozoic Kiggavik uranium deposit, Nunavut, Canada." Canadian Journal of Earth Sciences 57, no. 11 (November 2020): 1312–23. http://dx.doi.org/10.1139/cjes-2018-0318.
Full textAbstract:
The Thelon Basin is temporally and spatially related to the Athabasca Basin in Saskatchewan, Canada, which hosts the highest-grade unconformity-related uranium deposits in the world. Several uranium deposits occur within the Aberdeen sub-basin of the Thelon Basin, and it has been suggested that they may also be unconformity-related deposits. However, the genesis of the deposits is still debated and the age of the uranium mineralization event remains loosely constrained. In this study, we use secondary ion mass spectrometry to measure three sulphur (S) isotopes in pyrite from the Kiggavik deposit to constrain the sources of sulphur. We use this information to determine whether these sulphides, if dated by the Re–Os method, would provide a better constraint on the timing of uranium mineralization. The Kiggavik deposit comprises three zones (Main, Centre, and East) that formed from ∼200 °C fluids at ∼1600 Ma. Non-hydrothermal pyrite and galena from all three zones have a wide range of δ34S values, from −41.2‰ to +37.4‰. The Δ33S values (>0‰) indicate recycling of mass independent fractionation sulphur, suggesting that pyrite from the Kiggavik deposit derived sulphur from the Neoarchean metagraywacke host rock. The preservation of these anomalous Δ33S values suggests that the pyrite formed from low-temperature processes rather than hydrothermal processes. Low-temperature, high-latitude fluids may have been involved in the formation of the pyrite because some of these sulphides are also associated with uranium minerals that are devoid of Pb and contain corroded calcite. Based on these data, Re–Os geochronology of these sulphides would not yield an age that would constrain the timing of hydrothermal uranium mineralization.
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Ding, Bo, Hongxu Liu, Deru Xu, Linfei Qiu, and Weihong Liu. "Mineralogical Evidence for Hydrothermal Uranium Mineralization: Discovery and Genesis of the Uranyl Carbonate Minerals in the BLS U Deposit, SW Songliao Basin, Northeast China." Minerals 13, no. 3 (February 28, 2023): 339. http://dx.doi.org/10.3390/min13030339.
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Diabase intrusions have been widely found in sandstone-type U deposits of the southwestern Songliao Basin, indicating diabase-related hydrothermal fluids might play an important role in this type of U mineralization. The first discovery of U-bearing carbonate minerals in the BLS U deposit provides an opportunity for understanding hydrothermal U mineralization and its relationship to diabase intrusions. U-bearing carbonate minerals occurred as thin shells generally ringing ankerite and then surrounded by colloidal pyrite through examination of scanning electron microscopy and energy dispersive spectroscopy. They can be interpreted as uranyl carbonate minerals, with the empirical formula of Ca2.7Fe0.9Mg0.4 (UO2) (CO3)5•9.6H2O, based on infrared absorption spectroscopy and electron microprobe. The formation of uranyl carbonate minerals is most likely related to the CO2-rich hydrothermal fluids from diabase intrusions according to its occurrence state, but the key factors are that the Ca-UO2-CO3 ternary complexes should have been produced in ore-forming hydrothermal fluids and adsorption of ankerite on ternary complexes. Thereby, a potential diabase-related hydrothermal U mineralization model for sandstone-type U deposits can be proposed. The ore-forming fluids that originated from diabase-related hydrothermal are formed through continuously extracting the adsorbed U6+ and dissolving the early U minerals. Then, U in the ore-forming hydrothermal fluids was migrated and transported probably either as uranyl carbonate ions or as Ca-UO2-CO3 ternary complexes. The former is easy to precipitate in the form of pitchblende dispersed in the fossil wood cells, ringing pyrite, and occurring along the edge of adsorbents at the site of reducing capacity change, while the latter will extremely inhibit the reduction of U6+, eventually leading to the precipitation of uranyl carbonate minerals ringing ankerite by adsorption. The above research results can provide mineralogical evidence for hydrothermal U mineralization in sandstone-type U deposits of the Songliao Basin.
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Xue, Song, Yaoling Niu, Yanhong Chen, Yining Shi, Boyang Xia, Peiyao Wang, Hongmei Gong, Xiaohong Wang, and Meng Duan. "Iron Isotope Fractionation during Skarn Cu-Fe Mineralization." Minerals 11, no. 5 (April 22, 2021): 444. http://dx.doi.org/10.3390/min11050444.
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Fe isotopes have been applied to the petrogenesis of ore deposits. However, the behavior of iron isotopes in the mineralization of porphyry-skarn deposits is still poorly understood. In this study, we report the Fe isotopes of ore mineral separations (magnetite, pyrite, chalcopyrite and pyrrhotite) from two different skarn deposits, i.e., the Tonglvshan Cu-Fe skarn deposit developed in an oxidized hydrothermal system and the Anqing Cu skarn deposit developed in a reduced hydrothermal system. In both deposits, the Fe isotopes of calculated equilibrium fluids are lighter than those of the intrusions responsible for the skarn and porphyry mineralization, corroborating the “light-Fe fluid” hypothesis. Interestingly, chalcopyrite in the oxidized-Tonglvshan skarn deposit has lighter Fe than chalcopyrite in the reduced-Anqing skarn deposit, which is best understood as the result of the prior precipitation of magnetite (heavy Fe) from the ore fluid in the oxidized-Tonglvshan systems and the prior precipitation of pyrrhotite (light Fe) from the ore fluid in the reduced-Anqing system. The δ56Fe for pyrite shows an inverse correlation with δ56Fe of magnetite in the Tonglvshan. In both deposits, the Fe isotope fractionation between chalcopyrite and pyrite is offset from the equilibrium line at 350 °C and lies between the FeS-chalcopyrite equilibrium line and pyrite-chalcopyrite equilibrium line at 350 °C. These observations are consistent with the FeS pathway towards pyrite formation. That is, Fe isotopes fractionation during pyrite formation depends on a path from the initial FeS-fluid equilibrium towards the pyrite-fluid equilibrium due to the increasing extent of Fe isotopic exchange with fluids. This finding, together with the data from other deposits, allows us to propose that the pathway effect of pyrite formation in the Porphyry-skarn deposit mineralization is the dominant mechanism that controls Fe isotope characteristics.
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Mederer, Johannes, Robert Moritz, Massimo Chiaradia, Richard Spikings, Jorge E. Spangenberg, and David Selby. "Ore Formation During Jurassic Subduction of the Tethys Along the Eurasian Margin: Constraints from the Kapan District, Lesser Caucasus, Southern Armenia." Economic Geology 114, no. 7 (November 1, 2019): 1251–84. http://dx.doi.org/10.5382/econgeo.4640.
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Abstract The Kapan mining district in the southernmost Lesser Caucasus is one of the few locations along the central Tethyan metallogenic belt where ore-forming processes were associated with magmatic arc growth during Jurassic Tethys subduction along the Eurasian margin. Three ore deposits of the Kapan district were investigated in this study: Centralni West, Centralni East, and Shahumyan. The ore deposits are hosted by Middle Jurassic andesitic to dacitic volcanic and volcaniclastic rocks of tholeiitic to transitional affinities below a late Oxfordian unconformity, which is covered by calc-alkaline to transitional Late Jurassic-Early Cretaceous volcanic rocks interlayered with sedimentary rocks. The mineralization consists of veins, subsidiary stockwork, and partial matrix replacement of breccia host rocks, with chalcopyrite, pyrite, tennantite-tetrahedrite, sphalerite, and galena as the main ore minerals. Centralni West is a dominantly Cu deposit, and its host rocks are altered to chlorite, carbonate, epidote, and sericite. At Centralni East, Au is associated with Cu, and the Shahumyan deposit is enriched in Pb and Zn as well as precious metals. Both deposits contain high-sulfidation mineral assemblages with enargite and luzonite. Dickite, sericite, and diaspore prevail in altered host rocks in the Centralni East deposit. At the Shahumyan deposit, phyllic to argillic alteration with sericite, quartz, pyrite, and dickite is dominant with polymetallic veins, and advanced argillic alteration with quartz-alunite ± kaolinite and dickite is locally developed. The lead isotope composition of sulfides and alunite (206Pb/204Pb = 18.17–18.32, 207Pb/204Pb = 15.57–15.61, 208Pb/204Pb = 38.17–38.41) indicates a common metal source for the three deposits and suggests that metals were derived from magmatic fluids that were exsolved upon crystallization of Middle Jurassic intrusive rocks or leached from Middle Jurassic country rocks. The δ18O values of hydrothermal quartz (8.3–16.4‰) and the δ34S values of sulfides (2.0–6.5‰) reveal a dominantly magmatic source at all three deposits. Combined oxygen, carbon, and strontium isotope compositions of hydrothermal calcite (δ18O = 7.7–15.4‰, δ13C = −3.4−+0.7‰, 87Sr/86Sr = 0.70537–0.70586) support mixing of magmatic-derived fluids with seawater during the last stages of ore formation at Shahumyan and Centralni West. 40Ar/39Ar dating of hydrothermal muscovite at Centralni West and of magmatic-hydrothermal alunite at Shahumyan yield, respectively, a robust plateau age of 161.78 ± 0.79 Ma and a disturbed plateau age of 156.14 ± 0.79 Ma. Re-Os dating of pyrite from the Centralni East deposit yields an isochron age of 144.7 ± 4.2 Ma and a weighted average age of the model dates of 146.2 ± 3.4 Ma, which are younger than the age of the immediate host rocks. Two different models are offered, depending on the reliability attributed to the disturbed 40Ar/39Ar alunite age and the young Re-Os age. The preferred interpretation is that the Centralni West Cu deposit is a volcanogenic massive sulfide deposit and the Shahumyan and Centralni East deposits are parts of porphyryepithermal systems, with the three deposits being broadly coeval or formed within a short time interval in a nascent magmatic arc setting, before the late Oxfordian. Alternatively, but less likely, the three deposits could represent different mineralization styles successively emplaced during evolution and growth of a magmatic arc during a longer time frame between the Middle and Late Jurassic.
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Lin, Bing Xia, Ming Guo Deng, and Xu Wen Liang. "Characteristic Analysis of Texture and Structure of Ores and Genesis of Luziyuan Pb-Zn Polimetallic Deposit in Zhenkang, Yunnan, China." Advanced Materials Research 734-737 (August 2013): 311–15. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.311.
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The main ore structure of the deposit include: disseminated structure, emulsion droplet-like structure, banded structure, vein-like structure, the massive structure, brecciated structure, etc.; The main ore texture include: crystalline granular texture, the replacement texture, solid solution separation texture, interstitial texture, etc. According to the ore fabric characteristics and metal minerals and gangue mineral combination, type and shape since the degree and mineral in space analysis of characteristics of the relationship, the mining area can be roughly divided into three periods: sedimentary diagenesis stage, the initial formation of the sources, hydrothermal reformation metallogenic stage and supergene stage. It was considered that Luziyuan Pb-Zn polymetallic deposit is the hydrothermal deposits for early deposition, the late hydrothermal transformation.
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Perry, Emily P., and Alexander P. Gysi. "Rare Earth Elements in Mineral Deposits: Speciation in Hydrothermal Fluids and Partitioning in Calcite." Geofluids 2018 (2018): 1–19. http://dx.doi.org/10.1155/2018/5382480.
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Studying the speciation and mineral-fluid partitioning of the rare earth elements (REE) allows us to delineate the key processes responsible for the formation of economic REE mineral deposits in natural systems. Hydrothermal REE-bearing calcite is typically hosted in carbonatites and alkaline rocks, such as the giant Bayan Obo REE deposit in China and potential REE deposits such as Bear Lodge, WY. The compositions of these hydrothermal veins yield valuable information regarding pressure (P), temperature (T), salinity, and other physicochemical conditions under which the REE can be fractionated and concentrated in crustal fluids. This study presents numerical simulation results of the speciation of REE in aqueous NaCl-H2O-CO2-bearing hydrothermal fluids and a new partitioning model between calcite and fluids at different P-T-x conditions. Results show that, in a high CO2 and low salinity system, bicarbonate/carbonate are the main transporting ligands for the REE, but predominance shifts to chloride complexes in systems with high CO2 and high salinity. Hydroxyl REE complexes may be important for the solubility and transport of the REE in alkaline fluids. These numerical predictions allow us to make quantitative interpretations of hydrothermal processes in REE mineral deposits, particularly in carbonatites, and show where future experimental work will be essential in improving our modeling capabilities for these ore-forming processes.
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Qi, Wufu, Xianfeng Cheng, Qianrui Huang, Yu Liu, Shirong Ran, and Yanqiang Zhang. "Ore Features and Gold Occurrence of the Manlonggou Gold Deposit, Southeast Yunnan Province, China." IOP Conference Series: Earth and Environmental Science 906, no. 1 (November 1, 2021): 012002. http://dx.doi.org/10.1088/1755-1315/906/1/012002.
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Abstract The Yunnan-Guizhou-Guangxi “Golden Triangle” is one of the famous Carlin-type gold deposits in China and even in the world. Manlonggou gold deposit is a newly discovered gold deposit in this area. The host rocks are mainly lithic quartz sandstone, siltstone and silty mudstone above Caledonian unconformity. The main minerals in ores are natural gold, limonite, hematite, pyrite and so on. The occurrence state of gold is fine exposed and semi-exposed natural gold, as well as gold encased by limonite, carbonate, quartz and silicate minerals. The deposit can be a fine grain hydrothermal altered gold deposit with the origin of tectonic-medium-low temperature hydrothermal percolation.