Letteratura scientifica selezionata sul tema "Gold mineral system"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Gold mineral system".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Articoli di riviste sul tema "Gold mineral system":
1
Cai, Liu Lu, Shuang Liu, Wen Juan Li, Cheng Ying Zhou, Wei Qu e Yong Sheng Song. "Process Mineralogy of Jinshan Gold Ore Based on Mineral Liberation Analysis System". Advanced Materials Research 1010-1012 (agosto 2014): 1613–17. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.1613.
Abstract (sommario):
Traditional measurement and modern SEM-based mineral liberation analysis (MLA) system were employed to obtain the process mineralogy characteristic of Jinshan gold ore which had high Au (6.20g/t) and low sulfide (0.25%). XBSE, XBSE_STD and SPL_Lt MLA modes are used in this case, which make the results timely, reliable and quantitative. The gold behaves irregular granular native gold or silver-bearing native gold of which the Au content ranging from 93%to 100%. Gold mainly occurred as liberated or in gold-carrying gangue minerals, such as quartz and biotite,rarely in pyrite in the form of fissure gold, inter-crystalline gold or inclusion gold . The particle size of the Gold minerals range from 0.001mm to 0.010mm , which is too fine to recover from beneficiating method. Combined process should be adopted.
2
Ji, Qiang, Guangsheng Li, Xingfu Zhu, Tengyue Gao, Guanglin Qin, Chao Xu, Mingming Cai et al. "Process Mineralogy Automatic Detection System in Research of a Gold Polymetallic Mine". Journal of Physics: Conference Series 2428, n. 1 (1 febbraio 2023): 012009. http://dx.doi.org/10.1088/1742-6596/2428/1/012009.
Abstract (sommario):
Abstract Automatic process mineralogy detection system has been widely used in beneficiation process parameters detection, cause finding, and defect diagnosis in concentrators. A gold ore composition in Shandong is more complex, and recovery is difficult. To clarify the ore properties, mineral composition, main minerals, embedded characteristics, and monomer dissociation characteristics, the scanning electron microscope, BPMA, and energy spectrometer are used for the ore sample process mineralogy research to provide a reliable basis for the study of the selection process. The research shows that the main valuable elements in the ore are gold and copper, copper and gold symbiotic ore. Meanwhile, the gold, copper, and iron-containing minerals are closely embedded, pyrite and magnetite are the main minerals for sulfur recovery, and magnetite and limonite are the main minerals for producing iron concentrate. Automatic process mineralogy has played an important role in determining the selectability research and beneficiation process of the polymetallic gold ore.
3
D’yachkov, Boris A., Ainel Y. Bissatova, Marina A. Mizernaya, Sergey V. Khromykh, Tatiana A. Oitseva, Oxana N. Kuzmina, Natalya A. Zimanovskaya e Saltanat S. Aitbayeva. "Mineralogical Tracers of Gold and Rare-Metal Mineralization in Eastern Kazakhstan". Minerals 11, n. 3 (28 febbraio 2021): 253. http://dx.doi.org/10.3390/min11030253.
Abstract (sommario):
Replenishment of mineral resources, especially gold and rare metals, is critical for progress in the mining and metallurgical industry of Eastern Kazakhstan. To substantiate the scientific background for mineral exploration, we study microinclusions in minerals from gold and rare-metal fields, as well as trace-element patterns in ores and their hosts that may mark gold and rare-metal mineralization. The revealed compositions of gold-bearing sulfide ores and a number of typical minerals (magnetite, goethite, arsenopyrite, antimonite, gold and silver) and elements (Fe, Mn, Cu, Pb, Zn, As, and Sb) can serve as exploration guides. The analyzed samples contain rare micrometer lead (alamosite, kentrolite, melanotekite, cotunnite) and nickel (bunsenite, trevorite, gersdorffite) phases and accessory cassiterite, wolframite, scheelite, and microlite. The ores bear native gold (with Ag and Pt impurities) amenable to concentration by gravity and flotation methods. Multistage rare-metal pegmatite mineralization can be predicted from the presence of mineral assemblages including cleavelandite, muscovite, lepidolite, spodumene, pollucite, tantalite, microlite, etc. and such elements as Ta, Nb, Be, Li, Cs, and Sn. Pegmatite veins bear diverse Ta minerals (columbite, tantalite-columbite, manganotantalite, ixiolite, and microlite) that accumulated rare metals late during the evolution of the pegmatite magmatic system. The discovered mineralogical and geochemical criteria are useful for exploration purposes.
4
Safronov, P. P., e I. V. Kuznetsova. "AUTIGENIC MINERAL FORMATION AS AN OBJECTIVE FACTOR OF TRANSFORMATION OF TECHNOGENIC PLACERS". Geology and mineral resources of Siberia, n. 3 (2021): 83–93. http://dx.doi.org/10.20403/2078-0575-2021-3-83-93.
Abstract (sommario):
The paper presents the data of analytical scanning electron microscopy and mineralogical methods for studying the morphology and chemical composition of spiral man-induced products, metal spheroids and native gold from the alluvial mining waste. In all samples, including the tungsten “spiral”, mercurous gold was found. The spheroids were diagnosed as lead ones with a fine impregnation of alumina-silicate substance, antimony and copper ones with autigenic isometric and xenomorphic mineral deposits on the surface, etc. The inclusion of carbon in many newly formed minerals confirms the leading role of this element in the process of technogenic mineral formation as a reducing agent. The identified chemical diversity of numerous ore and rock phases is explained by complex physico-chemical processes occurring in the technogenic system, in which not only the residual gold is transformed, but also new ore-mineral complexes, including gold-containing ones, arise.
5
Mykhailov, V., S. Vyzhva e S. Paiuk. "SYSTEM ANALYSIS OF THE MINERAL RAW MATERIAL BASE OF STRATEGIC MINERALS OF UKRAINE". Visnyk of Taras Shevchenko National University of Kyiv. Geology, n. 4 (99) (2022): 36–44. http://dx.doi.org/10.17721/1728-2713.99.05.
Abstract (sommario):
A systematic analysis of the mineral resource base (MRB) of strategically important minerals for the Ukrainian economy is carried out. Four categories of strategic minerals from the point of view of their investment attractiveness are identified: traditional (iron, manganese, titanium, uranium, kaolin, sand molding, building stones, quartz raw materials, refractory clay); highly promising (rare earths, zirconium and hafnium, lithium, scandium, germanium, graphite, potassium salts, abrasive raw materials, piezooptical raw materials); promising (nickel, cobalt, chromium, aluminum, copper, tantalum and niobium, beryllium, gold, phosphorite, apatite, fluorspar, glauconite, limestones for sugar industry, flux limestones and dolomites, bentonite clays, feldspar, rough semi-precious stones); with unclear prospects (vanadium, lead and zinc, tungsten, molybdenum, platinum minerals, strontium, magnesium, arsenic, rubidium, cesium, barite, boron, dawsonite, bromine and iodine, mineral sorbents, high alumina raw materials, raw materials for mineral production of paints, fluorine, sulfur). Factors and criteria of investment attractiveness are determined and its expert assessment for deposits of metallic and industrial minerals and rocks of Ukraine is carried out, ways of creation of harmoniously developed balanced MRB of strategic minerals are shown.
6
Tsikon, Serhii, e Uliana Lushchak. "Research and evaluation criteria of hydrothermal oregination of rakhiv gold ore region (Transcarpathia)". Visnyk of the Lviv University. Geology Series 35, n. 35 (2021): 10–25. http://dx.doi.org/10.30970/vgl.35.02.
Abstract (sommario):
Complex of the searching-valuation criterions of the Rakhiv ore region gold mineralization have been elaborated. The main amongst them are mineralogy-genetic, geology-structural, thermobarogeochemical and mineralogy-physical ones. The main favorable criteria for gold are: the spread of productive mineral associations and syngeneic fluid inclusions with them; carbon dioxide-water composition of mineral-forming fluids, inclusions in minerals, the density of which does not exceed 0.5 g/cm3; medium temperature conditions of mineral formation (280–120 °С); distribution and sequence (from {100} + {210} to {210}) of crystallization of combined forms of pyrite, which are characterized by: mainly np- and p-conductivity and numerical vectors (in the coordinate system RV – average), oriented towards higher values hole conductivity; the presence of galena, the value of thermoelectric force which is more than 800 μV/deg. Based on the developed criteria, we offered a number of specific recommendations on the prospects of the studied ore occurrences, Saulyak deposit and Rakhiv gold ore district in general.
7
Ernawati, Rika, Arifudin Idrus e Himawan Tri Bayu Murti Petrus. "Mineralogy and Geochemistry of Gold Ore Low Sulfidation -Epithermal at Lamuntet, Brang Rea, West Sumbawa District, West Nusa Tenggara Province". Journal of Geoscience, Engineering, Environment, and Technology 4, n. 3 (21 settembre 2019): 198. http://dx.doi.org/10.25299/jgeet.2019.4.3.1653.
Abstract (sommario):
There are two Artisanal Small scale Gold Mining (ASGM) location in Lamuntet, Brang Rea Subdistrict, West Nusa Tenggara Regency, namely Nglampar and Song location. Nglampar and Song location are included in the low sulfidation epithermal gold deposit system. The research purposes to analyze mineralogy and geochemistry of gold vein deposits and determine system of low sulfidation gold ore in Nglampar, Lamuntet Village. The methods used to determine the mineralogy of gold vein deposits are petrography, mineragraphy and X-ray diffractometer (XRD) analysis, while geochemical analysis using Scanning Electron Microscope (SEM) with Energy Dispersive X-Ray Spectroscopy (EDS), Fire Assay (FA) and Atomic Absorption Spectrophotometry (AAS). The results showed that the minerals contained were quartz (Qz), sericite (Ser), Chalcedon (Chc), chlorite (Chl), pyrite (Py), sphalerite (Sph), galena (Gn) , gold (Au), chalcopyrite (Cp), argentite (Ag), arsenopyrite (Apy), Azurit (Az), Malakit (Mal) and bornite (Bn). Abundant mineral availability such as sphalerite, galena, chalcopyrite and arsenopyrite are characterized by high levels of Zn, Pb, Cu and As the metal in vein deposits. This can be seen on the chemical content of ore in gold vein deposits ie Au 0.1 ppm -27.8 ppm, Ag 3 ppm-185 ppm, Pb 101 ppm - 35,800 ppm, Zn 73 ppm-60,200 ppm, Cu 26 ppm - 1,740 ppm, and As 150 ppm - 6,530 ppm. Based on the results of SEM-EDS analysis shows that the type of gold mineral is the electrum because of the content of Ag> 20%. Based on those characteristics of the mineralogy and geochemistry in this study showed that low sulfidation gold ore in this area is categorized as polymetallic gold-silver system.
8
Zar, Aung Tay, I. Wayan Warmada, Lucas Donny Setijadji e Koichiro Watanabe. "Geochemical Characteristics of Metamorphic Rock-Hosted Gold Deposit At Onzon-Kanbani Area, Central Myanmar". Journal of Geoscience, Engineering, Environment, and Technology 2, n. 3 (1 settembre 2017): 191. http://dx.doi.org/10.24273/jgeet.2017.2.3.410.
Abstract (sommario):
Gold and associated base metal mineralization of Onzon-Kabani area located in the western border of generally N-S trending Mogoke Metamorphic Belt where well-known Sagaing fault is served as a western boundary of this area. In this research area, many artisanal and small-scale gold mines were noted in last three decades. Gold mineralization is hosted in marble and gneiss unit of research area but most common in marble unit. Variety of igneous intrusions are also observed in research area. Mineralizations are observed as fissure filling veins as well as lesser amount of disseminated nature in marble unit. Mineralogically, gold are associated with other base metal such as pyrite, galena, sphalerite, chalcopyrite, marcasite and arsenopyrite. Hydrothermal alteration halos are developed in peripheral of hydrothermal conduits or mineralization veins from proximal to distal such as 1) silicic, 2) sericite-illite, and 3) propylitic alteration. Most of hydrothermal minerals from each altered zones showed that near neutral condition of pH (e.g. adularia, calcite, illite, sericite and chlorite). Alternatively, hydrothermal alteration zones that show with ore minerals such as native gold, electrum, sphalerite, galena, chalcopyrite, arsenopyrite and marcasite which mostly observed in silicic alteration zone. Typical boiling characters of vein textures and fluid inclusion petrography are observed in hydrothermal system of research area. Boiling, cooling and mixing are possiblily responsible for gold deposition in hydrothermal system. In this paper, authors are documented to clarify the type of mineralization based on hydrothermal alterations, ore and gangue mineral assemblages and fluid inclusion study. All of these data can describe and play an important role for both with respect to understanding deposit genesis and in mineral exploration.
9
Zar, Aung Tay, I. Wayan Warmada, Lucas Donny Setijadji e Koichiro Watanabe. "ALTERATION, VEIN TEXTURES AND FLUID INCLUSION PETROGRAPHY OF METAMORPHIC ROCK-HOSTED GOLD DEPOSIT AT ONZONKANBANI AREA, CENTRAL MYANMAR: IMPLICATION FOR ITS GENESIS". ASEAN Engineering Journal 8, n. 2 (1 dicembre 2018): 48–63. http://dx.doi.org/10.11113/aej.v8.15502.
Abstract (sommario):
Gold and base metal mineralization of Onzon-Kabani area is located at the western part of Mogok Metamorphic Belt in central Myanmar, where the well-known Sagaing Fault serves as its western boundary. Artisanal and small-scale gold operations started here three decades ago on gold mineralization hosted in marble and gneiss. Mineralization occurs as fracture-filling veins of several types: gold-bearing quartz vein, base metal quartz-carbonate vein, and carbonate base metal sulfides vein. Three types of hydrothermal alteration zones develop from the proximal to distal zone of hydrothermal conduit: silicic, sericite-illite and propylitic alteration. Alteration mineral assemblages consist of quartz, calcite, sericite, adularia, epidote, chlorite, illite and smectite which are typical of neutral pH hydrothermal fluid. The presence of adularia and calcite within veins indicate boiling event of near-neutral pH condition. Common vein textures of quartz and calcite are banded, crustiform, bladed calcite, lattice, mosaic or jigsaw, cockade, comb and zonal. Boiling-related mineral textures (e.g. banded, bladed and lattice) and fluid inclusion characteristics of coexisting liquid-rich and vapor-rich fluid inclusions have been identified in mineralized samples. Common ore minerals are pyrite, sphalerite, galena, chalcopyrite and minor marcasite, electrum and native gold. Gold is mostly associated with quartz gangue, pyrite, sphalerite and galena. Fluid-inclusion study suggests the presence of liquid-rich and vapor-rich fluid inclusions which were trapped in boiling fluid at homogenization temperature of 159 to 315°C and moderate salinity of 0.88 to 12.51 wt.% NaCl equivalent. It is concluded that despite mesothermal gold system is more typical style of gold mineralization in the Mogok Metamorphic Belt, it is not the type of mineralization in the Onzon-Kanbani area. Instead, a low-sulfidation epithermal system is more characteristic to be present here. The knowledge generated from this study can serve as a guide in understanding new deposit type as well as mineral exploration in the region.
10
FERNANDES, CARLOS JOSÉ, GÊNOVA MARIA PULZ, ALESSANDRO SILVA OLIVEIRA, MARIA DO CARMO LIMA E CUNHA, ELZIO SILVA BARBOZA, FRANCISCO EGIDIO PINHO e ÁLVARO PIZZATO QUADROS. "Diferenças Químicas e Texturais entre os Veios de Quartzo Férteis e Estéreis no Depósito Aurífero Pau-a-Pique (Grupo Aguapeí, Estado de Mato Grosso)". Pesquisas em Geociências 26, n. 2 (31 dicembre 1999): 91. http://dx.doi.org/10.22456/1807-9806.21128.
Abstract (sommario):
The quartz veins in the Pau-a-Pique gold deposit hosted in Aguapeí Group metassediments have textural, paragenetic and chemical characteristics that provide prospectives criteria for gold. Gold disseminations occur in the quartz vein system and in the hydrothermal halo. The highest gold grades are within quartz veins that have comb, saccaroidal and replacement textures. The barren veins show ribbon and buck textures. Both fertile and barren veins exhibit a lack of correlation between gold grades and of the other elements (As, Fe, Sc and Ta). This behavior indicates that gold grades might be adequate chemical criteria for distinction between barren and the fertile veins. Gold grains appear associated to martite and oxihydroxides pseudomorphs that replace the ore minerals in veins. The mineral assemblage and textures of the quartz veins, suggest a gold remobilization due to Eh-pH fluctuations related to interaction between the ore and the meteoric solutions.
Tesi sul tema "Gold mineral system":
1
Claypoole, Micah N. "Mineral Ridge| A Late Cretaceous Orogenic Gold System in the Miocene Silver Peak-Lone Mountain Metamorphic Core Complex". Thesis, University of Nevada, Reno, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10821834.
Abstract (sommario):
Gold deposits in rocks of the Silver Peak metamorphic core complex in west-central Nevada are contained in highly deformed, sheeted milky quartz veins that cut Neoproterozoic metasedimentary rocks and Cretaceous peraluminous granite and migmatite. Gold production at Mineral Ridge since discovery in 1864 has been approximately 1 million oz. Gold-bearing veins are concentrated in a major low-angle ductile shear system active during the Late Cretaceous. However, a broadly coincident brittle detachment cuts the ductile shear, separating metasedimentary and foliated granitic rocks from overlying non-metamorphosed Cambrian carbonates and Cenozoic volcanics. The Mineral Ridge biotite-muscovite granite pluton bounds the ductile shear along its roof, defining a wedge of prospective metamorphic rocks generally <50-m-thick. Zones of intense shearing generally correspond to highest vein density and therefore, gold grades, and such zones are overprinted with strong but narrowly defined quartz-sericite-pyrite-carbonate alteration. Vein boudins are subparallel to the strong planar to anastomosing shear fabric best developed over 1-10 meter thicknesses at contacts between muscovite schist and/or marble, and foliated granite. Goldbearing veins contain Au:Ag of ≥4, zoned base metals, low As, Sb, and Hg, but high Bi, the latter correlating with gold.
Vein-bearing granites at Mineral Ridge yield U/Pb zircon ages of 91.7+/-0.3 Ma and 89.9+/-0.5 Ma and likely derive from crustal melts during peak metamorphism. Hydrothermal monazite in goldbearing quartz veins yielded a U/Pb age of 76.0+/-1.8 Ma, indicating veins are unrelated to granites and formed during retrograde greenschist conditions. Previous cooling ages on mica in granites of ∼42 and 53 Ma further define the cooling path to ∼300°C. Mineral Ridge is interpreted as an orogenic gold system associated with a brittle-ductile shear that formed at depths as much as 11-20 km during the waning stages of Late Cretaceous Sevier contraction. Major exhumation occurred in the late Miocene in association with detachment and transtension in the Walker Lane deformation belt.
2
Adelman, Jessica. "Mineral interactions in a gold mining environment: change in oxidation rate of stibnite as affected by the addition of varying amounts of pyrite in an oxygenated flow through system". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92390.
Abstract (sommario):
It is thought that a significant mechanism of stibnite (Sb2S3) oxidation in mine wastes is through contact with a mineral of greater rest potential (whereby the outer valence shell electrons operate at a higher energy level), such as pyrite (FeS2). The goal of this research is to determine if the oxidation of stibnite in an oxygenated flow through system was increased through contact with minerals of greater rest potential such as pyrite and arsenopyrite (FeAsS) and whether this electro-chemical reaction was affected by various ratios of stibnite to pyrite (or arsenopyrite) and slightly acidic (pH 5) to alkaline (7.5) pH conditions. Four column leaching experiments were carried out using various ratios of stibnite and pyrite (or arsenopyrite). When the two minerals were mixed in columns and leached with water, the treatment with the greatest amount of pyrite and least amount of stibnite (95% pyrite) had the highest cumulative amount of dissolved Sb (Exp #2- 16 730 mg Sb/kg stibnite). X-ray absorption near-edge structure (XANES) analysis of the solid phase revealed that the 95% pyrite treatment had the highest proportion of total Sb as Sb(V)-O species compared to all other mixed treatments and 100% stibnite. These results indicate that galvanic interactions had occurred between stibnite and pyrite. Using a solution buffered to pH 7.5, it was possible to determine the effect of a high pH environment on these galvanic interactions between stibnite and pyrite. Under slightly alkaline pH conditions, the 95% pyrite treatment had the highest cumulative amount of dissolved Sb (Exp #3- 18 090 mg Sb/kg stibnite) and this amount was similar to the 95% pyrite treatment in experiment #2. XANES analysis revealed a smaller proportion of total Sb as oxide species in this experiment compared to experiment #2, possibly due to the formation of a soluble Sb complex with HCO3-. In Experiment #4, the leaching with deionized water of a mixed system containing stibnite and arsenopyriteOn croit qu'un des mécanismes importants de dissolution de la stibnite (Sb₂S₃) dans les résidus miniers est par contact avec un minéral ayant un plus fort potentiel électrique, tel que la pyrite (FeS₂). L'objectif de la recherche était de déterminer l'impact du ratio stibnite vs. pyrite et l'effet du pH sur le taux de dissolution de la stibnite. Quatre essais de lessivage en colonnes ont été réalisés. Les deux premiers essais de lessivage avec de l'eau déionisée ont montré que le traitement contenant la plus forte proportion de pyrite (95% pyrite) a résulté en la plus grand quantité cumulative de Sb dissous (Exp #2-16730 mg Sb/kg stibnite). L'analyse spectroscopique par absorption des rayons-X (XANES) de la phase solide a révélé que la proportion de Sb total sous forme Sb(V)-O était plus importante dans le traitement 95% pyrite comparé à tous les autres traitements mixtes et au traitement contrôle de 100% stibnite. Ces observations indiquent que des interactions galvaniques ont eu lieu entre la stibnite et la pyrite. En utilisant une solution tamponnée à pH 7.5, il fut possible de déterminer l'effet d'un pH légèrement alcalin sur ces interactions entre la stibnite et la pyrite. Dans ces conditions, la quantité maximale de Sb dissous a été atteinte dans le traitement 95% pyrite (Exp #3-18090 mg Sb/kg stibnite), ce qui est comparable au traitement 95% pyrite dans l'expérience #2 de lessivage à l'eau. Cependant, l'analyse XANES a révélé une proportion moindre du Sb total sous forme d'oxide dans l'essai de lessivage à pH 7.5, possiblement en raison de la formation d'un complexe soluble entre Sb et HCO₃-. L'expérience #4 a testé l'impact de l'arsenopyrite sur la dissolution de la stibnite lors d'un lessivage à l'eau. Dans ce cas, le traitement 95% arsenopyrite (Exp #4-10311 mg Sb/kg stibnite) a libéré moins de Sb en solution comparé au traitement 95% pyrite de l'expérience #2, et ce résultat s'explique par la plus p
3
Perret, Julien. "Répartition spatio-temporelle du système métallogénique de l’or panafricain au sein du bouclier arabo-nubien : étude multiscalaire le long de la suture de Keraf (Soudan)". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0117.
Abstract (sommario):
La compréhension des mécanismes permettant le transfert de l’or depuis les enveloppes internes de la Terre vers son écorce passe par l’étude de l’évolution géodynamique des segments de croûte dite juvénile, i.e., dérivée de matériel extrait directement du manteau. Le système métallogénique de l’or s’intéresse donc (i) à l’environnement géodynamique favorable à la fertilisation crustale en or et (ii) aux contextes tectono-métamorphiques ayant permis la remobilisation de ce réservoir et sa concentration. Cette démarche est appliquée aux sutures de Keraf et d’Atmur-Delgo au sein du bouclier arabo-nubien, le plus grand segment au monde de croûte juvénile néoprotérozoïque et l’une des principales provinces aurifères panafricaines, mis en place lors de la formation du supercontinent Gondwana. Deux pics d’activité magmatique à signatures isotopiques Hf et Nd suprachondritiques enregistrent la formation et la maturation de différents arcs insulaires entre 840-810 Ma et 760-655 Ma. La fertilisation crustale en or à l’échelle régionale résulterait de la longue durée de vie de l’arc insulaire de Keraf et de sa nature juvénile prédominante. La première phase de croissance crustale est associée à un événement aurifère mineur de nature magmato-hydrothermale au sein de l’arc de Keraf. La seconde période d’activité magmatique est enregistrée par les arcs insulaires de Keraf et d’Atmur-Delgo. Le couplage d’observations et de mesures réalisées du terrain au laboratoire illustre la continuité spatiale du contrôle structural des minéralisations postérieures. D’une part, un épisode minéralisateur a lieu vers 755-725 Ma, lors d’un continuum de déformation au faciès amphibolite inférieur attribué à l’accrétion tectonique dans le prisme sédimentaire en avant de l’arc d’Atmur-Delgo. À l’échelle microscopique, la minéralisation résulte de la remobilisation syn-métamorphique du stock d’or contenu par les sulfures préexistant. D’autre part, plusieurs gisements d’or orogénique sont exprimés sous forme de veines d’extension recoupant des corps intrusifs. Les veines minéralisées sont formées selon le mécanisme de faille-valve, en réponse à la réactivation épisodique et localisée de décrochements crustaux jusqu’à 550 Ma au sein de la suture de Keraf. Il s’agit des événements minéralisateurs exprimés par des veines aurifères les plus ancien et jeune décrits à ce jour au sein du bouclier arabo-nubien. L’application du système métallogénique permet de définir des clés d’exploration à l’échelle du district qui traduisent des processus magmatiques et contextes tectono-métamorphiques (e.g., reliques d’arc insulaire, prisme d’accrétion, décrochements tardi-orogéniques) contrôlant des minéralisations aurifères aux caractéristiques structurales, géochimiques et chronologiques distinctes dans la zone d’étude. Cette stratégie diffère singulièrement de l’approche typologique dont l’efficacité se limite à (i) un unique type de minéralisation et à (ii) la prospection à l’échelle du gisementThe understanding of mechanisms leading to the transfer of gold transfer from the Earth’s mantle and core towards the crust requires the study of the geodynamical evolution of juvenile crust portions, i.e., crystallized from melt directly extracted from the mantle. The gold mineral system thus combines the deciphering of crustal fertilization geodynamical processes and subsequent transient tectono-metamorphic settings favorable for remobilization of this metal-enriched reservoir and formation of mineralized occurrences. This approach is applied to the Keraf and Atmur-Delgo sutures which are part of the Arabian-Nubian shield, the world-largest track of Neoproterozoic juvenile crust and one of the main Pan-African gold provinces, resulting from the assembly of Gondwana. We report the existence of two magmatic events with suprachondritic Hf and Nd signals, recording the build-up and maturation of island arcs along these suture zones between 840-810 Ma and 760-655 Ma. The ~185 Myr-long lifespan of the Keraf island arc and its predominant juvenile nature likely accounted for crustal gold fertilization at the regional scale. The earliest crustal growth stage, only recorded along the Keraf suture, is coeval to minor magmatic-hydrothermal gold event. Both the Keraf and Atmur-Delgo sutures keep record of the second island arc magmatic event. The matching between field and laboratory data exemplifies the district- to microscopic-scale spatial continuity of structural control on later gold-bearing structures. On one hand, a gold event occurred between 755-725 Ma, coeval with high-strain progressive deformation under lower amphibolite facies metamorphism related to tectonic accretion of the sedimentary wedge at the Atmur-Delgo intra-oceanic subduction site. At the microscopic scale, the ore formation involved the syn-metamorphic remobilization of the preexisting gold budget in sulfides. On another hand, several orogenic gold deposits display intrusion-hosted mineralized extension veins. The fault-valve mechanism induced the formation of mineralized veins, triggered by episodic and localized reactivation of crustal strike-slip shears within the Keraf suture zone until 550 Ma. These two gold events are the oldest and youngest vein-type gold episodes reported throughout the Arabian-Nubian shield to this day, respectively. The mineral system approach therefore enables district-scale ore targeting by translating magmatic processes and tectono-metamorphic settings into environments and geological features (e.g., relics of an island arc and/or an accretionary wedge, presence of late collisional strike-slip shears) favoring the formation of gold occurrences with very distinct structural, geochemical and timing characteristics in the western Arabian-Nubian shield. This alternative view of ore deposits contrasts sharply with the typological strategy which targets a single class of ore occurrence with an effectiveness limited to the deposit scale
4
Gelber, Benjamin D. J. "A mineral systems approach to the development of structural targeting criteria for orogenic gold deposits in the Asankrangwa gold belt of the Kumasi Basin, South-west Ghana". Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/63143.
Abstract (sommario):
The Kumasi Basin in South-west Ghana lies at the centre of the best-endowed Paleoproterozoic gold province in the world. The Kumasi Basin and margins of the adjacent volcanic belts are host to six world class gold camps: (1) 62 Moz Obuasi camp, (2) 22 Moz Prestea-Bogoso camp, (3) 11 Moz Asanko Gold Mine camp, (4) 9 Moz Edikan camp, (5) 7 Moz Bibiani camp, (6) 5 Moz Chirano camp, as well as several additional minor gold camps and many more prospects. Cumulatively these camps account for>116 Moz of endowment and contribute to making south-west Ghana the greatest Paleoproterozoic gold province in the world. Gold deposits in the Kumasi Basin are shear zone hosted and mineralisation ranges from disseminated to massive sulphide refractory deposits, to free milling quartz vein style deposits. Structural relationships and age dating indicate that most deposits are genetically related and were formed during a single episode of gold mineralisation during the D4 NNW-SSE crustal shortening deformation event of the Eburnean Orogeny (2125 – 1980 Ma). The understanding of structural controls on mineralisation is critical for exploration success as it allows exploration to focus on areas where these structural controls exist. This study uses a mineral systems approach to understand the relationship between the geodynamic history and structural controls on gold mineralisation in the Kumasi Basin at various scales, and define targeting criteria which can be applied for the purpose of developing predictive exploration models for making new discoveries in the Asanko Gold Mine camp located in the Asankrangwa Belt. The study used a quantitative analysis to establish residual endowment potential in the Asankrangwa Belt, providing the basis for a business model and resulting exploration strategy. Once established, a Fry autocorrelation analysis was applied to identify trends in deposit and camp spatial distribution to which critical geological processes were ascribed. Observed trends were mapped from multi-scale geophysical data sets and through interpretation of existing geophysical structure models, and structural criteria for targeting orogenic gold deposits at the regional and camp scales were developed. Results show that different structural controls on mineralisation act at the regional and camp scale. At the regional scale the distribution of gold camps was found to be controlled by fundamental N-S and NW-SE basement structures with gold camps forming where they intersect NE-SW first and second order structural corridors. At the Asanko Gold Mine camp scale, deposit distribution was found to be related to the intersection between major second order D3 NE-SW shear zones, minor third order D4 NNE-SSW brittle faults, and cryptic NW-SE upward propagating basement structures. In addition to these structural criteria, deposits in the Asanko Gold Mine camp were found to be aligned along a NNE-SSW lineament caused by the interaction between the N-S basement structure and the NE-SW trending Asankrangwa Belt shear corridor.
5
Hardardóttir, Vigdís. "Metal-rich Scales in the Reykjanes Geothermal System, SW Iceland: Sulfide Minerals in a Seawater-dominated Hydrothermal Environment". Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19925.
Abstract (sommario):
Downhole sampling of unboiled liquid at 1350 and 1500 m depth in the seawater-dominated Reykjanes high-temperature geothermal system in Iceland shows that metal concentrations measured at surface are minimum values due to mineral precipitation in the wells; by analogy of similar tectonic setting, host rocks and fluid composition, the metal concentrations measured in many black smoker vents at the seafloor are also minima. Fluids in the Reykjanes geothermal system react with mid-ocean ridge basalt at temperatures as high as 346°C and contain Fe 9-140 ppm, Cu 14-17 ppm, Zn 5-27 ppm, Pb 120-290 ppb, 1-6 ppb Au, and 28-107 ppb Ag. Fluids discharged at surface from the same wells have orders of magnitude lower metal concentrations due to precipitation caused by boiling and vapor loss during depressurization. Upstream of the orifice plate at high pressure (40 bar, 252°C) the precipitates consist mainly of sphalerite and chalcopyrite with a trace of galena and bornite. At the orifice plate of old wells, the pressure decreased sharply to 11 bar (188°C), resulting in abundant deposition of amorphous silica together with minor sphalerite and traces of chalcopyrite. In new wells the pressure at the orifice plate decreases to 22 bar (220°C); this pressure decrease and concomitant boiling causes deposition of fine-grained bornite-digenite solid solution together with sphalerite and galena on the fluid flow control valve. In high-pressure wells (average wellhead pressure 45-35 bar) most metals (mainly as sphalerite) are deposited downstream of the orifice plate, with up to 950 ppm Au and 2.5 wt.% Ag. Bulk concentrations in the scales vary between 15-60 wt.% upstream and downstream of the orifice plate and diminish from there. Iron increases up well from 8 to ~20 wt.% and decreases downstream of the orifice plate from 6 to 2 wt.% at the separation station; Cu downhole is ~3 wt.% but increases to 25 wt.% on the fluid flow control valve and then decreases; Pb downhole 100s ppm but at the wellhead is ~3 wt.%, increasing to 15 wt.% at the fluid flow control valve, then decreasing sharply from there.
6
Cadenillas, Luna Hernán Ulises, Llontop Marco Antonio Manay e Salinas Walter Felipe Rodríguez. "Variabilidad en el Sistema de Medición de los Contenidos de Cobre y Oro en el Concentrado, entre el almacén de acopio y el punto de despacho y su posible impacto económico - Caso de estudio compañía minera en el norte del Perú". Master's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/652613.
Abstract (sommario):
El presente trabajo de investigación propone determinar el rango aceptable de variabilidad en el sistema de medición de los contenidos de cobre y oro en el concentrado, entre el almacén de acopio en puerto y el punto de despacho en mina, mediante la realización de una serie de análisis de las variables dentro del proceso de estudio a nivel de toma de muestras, preparación de la muestra, análisis en laboratorio y métodos estadísticos empleados, con la finalidad de determinar si el impacto económico para la empresa es significativo. Para lo cual se ha descrito el análisis económico del sector minero a nivel nacional e internacional. He allí de donde viene la importancia de las diferencias de los contenidos de cobre y oro entre los puntos de despacho y acopio de una unidad minera. Es decir, si no se tiene identificado cuales son las variables o rangos aceptables de las diferencias de cobre y oro no se podrá determinar cuál es el impacto económico real en la compañía.
El presente trabajo ha utilizado el método estadístico Anova y la pruebas de hipótesis t , así como análisis del sistema de medición MSA (Measurement System Analysis) usando Gage R & R, lo que nos ha permitido determinar que los sistemas de medición en ambos lugares (mina y almacén de acopio) se tiene que mejorar a través de estandarización de procesos: procedimientos de muestreo, capacitación a operarios, implementación y calibración de equipos similares, balances semanales entre ambos puntos. Esto nos permitirá disminuir la variabilidad entre los resultados de cobre y oro tanto en mina como en el almacén de acopio.The present research work proposes to determine the acceptable range of variability in the measurement system of the copper and gold contents in the concentrate, between the storage warehouse in port and the point of dispatch in the mine, by carrying out a series of analysis of variables within the study process at the level of sampling, sample preparation, laboratory analysis and statistical methods used, with the determination to determine if the economic impact for the company is significant. For which the economic analysis of the mining sector at national and international level has been described. This is where the importance of the differences in copper and gold content between the dispatch and storage points of a mining unit comes from. In other words, if the acceptable variables or ranges of the copper and gold differences are not identified, the real economic impact on the company cannot be determined. The present work has used the Anova statistical method and the hypothesis T tests, as well as analysis of the measurement system MSA (Measurement System Analysis) using Gage R&R, which has allowed us to determine that the measurement systems in both places (mine and storage warehouse) have to improve through the standardization of processes: sampling procedures, operator training, implementation and calibration of similar equipment, weekly balances between both points. This allows us to decrease the variability between copper and gold results both in the mine and in the storage warehouse.
Trabajo de investigación
7
Magalhães, Luciola Alves 1981. "Integração e analise espacial de dados para a geração de modelos prospectivos de mineralizações auriferas na região de Amapari - Amapa". [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287198.
Abstract (sommario):
Orientadores: Carlos Roberto de Souza Filho, Adalene Moreira SilvaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
Made available in DSpace on 2018-08-11T04:31:13Z (GMT). No. of bitstreams: 1 Magalhaes_LuciolaAlves_M.pdf: 40248865 bytes, checksum: 334d3cf05db7133f70c68a2eaba439fc (MD5) Previous issue date: 2008
Resumo: A área de estudo, compreendida nesta investigação, situa-se no estado do Amapá e possui uma importância especial visto que se trata de uma das últimas fronteiras exploratórias do país, onde grande parte do estado é protegida por parques nacionais e reservas indígenas. Inserida na Província Maroni-Itaicaiúnas, palco de uma variedade de mineralizações como ferro, manganês, cromita, ouro, diamante, bauxita, caolim e cassiterita, na área são reconhecidos terrenos do embasamento Arqueano, seqüências do tipo greenstone-belts (Província Vila Nova) e suítes intrusivas, coletivamente de evolução geológica complexa e com amplo potencial metalogenético. O Depósito Amapari é caracterizado como um depósito do tipo lode orogenético, onde os maiores teores de ouro são associados às zonas mais deformadas, encaixadas em um sistema de veios sulfetados, principalmente pirrotita. O objetivo desta dissertação compreendeu a investigação de métodos de análise e modelagem espacial guiada pelos dados e pelo conhecimento, visando o mapeamento de áreas com favorabilidade mineral para ouro na região do depósito Amapari. À etapa de modelagem precedeu-se o processamento e a interpretação dos dados aerogeofísicos (magnetometria e gamaespectrometria) de alta resolução espacial e densidade de amostragem (Projeto Rio Araguari-CPRM), visando a geração de produtos para o mapeamento geológico e exploração mineral na porção centro-sul do estado do Amapá. Com base no processamento dos dados aerogeofísicos, foram gerados mapas de domínios e lineamentos magnéticos e domínios gamaespectrométricos, a partir dos quais novas unidades litogeofísicas foram reconhecidas, assim como redefinida, com grande precisão, a extensão de unidades previamente mapeadas (e.g., corpos enderbíticos, complexos máficos ultramáficos e intrusivas graníticas). As estruturas magnéticas são multi-orientadas. O extenso lineamento denominado Cupixi Alto Jari aparece com destaque nos mapas aerogeofísicos, separando o Terreno Cinturão Jari e o Terreno Antigo Cupixi- Tartarugal Grande. As estruturas de direção NNW são predominantes e se associam, com maior freqüência, às mineralizações auríferas da região. Dados geológicos (1:100.000), dados aerogeofísicos e análises de ouro em amostras de sedimentos de corrente foram utilizados para a geração de modelos de favorabilidade. Os mapas gerados pelos métodos de pesos de evidência, lógica fuzzy e redes neurais artificiais, destacaram a área do depósito Amapari como um sítio altamente favorável à ocorrência de ouro, condição necessária para que o resultado fosse coerente com a premissa dos modelos, além de indicarem novos alvos potenciais à mineralização. Estes novos alvos foram validados no campo e através de mapas de detalhe de anomalias geoquímicas de Au contido no solo, gerados pela MPBA. As áreas identificadas pela modelagem espacial estão em franca concordância com as principais anomalias geoquímicas, demonstrando, desta forma, que a determinação de alvos exploratórios mais favoráveis baseada em métodos indiretos é coerente com a prospecção através de métodos diretos
Abstract: The study area is situated in the Amapá State and has a special interest since it comprises one of the last exploration frontiers in Brazil, where much of the state is protected by national parks and indigenous reserves. It is placed within the Maroni-Itacaiunas Province, where a variety of mineralizations as iron, manganese, chromite, gold, diamond, bauxite, kaolin and cassiterite have been described. The area hosts in the area are recognized Archaean basements, greenstone belts (Province Vila Nova) and intrusive rocks that collectively show a complex geological evolution and with an ample metallogenic potential. The Amapari deposit is characterized as an orogenic-type gold mineralization, where the highest contents of gold are associated with the most deformed rocks in a system of sulfide veins, mainly composed of pyrrhotite. This research is focused in the investigation of spatial data modelling by data-driven and knowledge-driven predictive methods, aiming the identification of potential areas for gold mineralization in the proximities of Amapari region. High spatial resolution airborne geophysical data (magnetometry and gama-spectrometry) (Project Rio Araguari-CPRM) was processed and interpreted, aiming to provide products for geologic mapping and mineral exploration for a large area in the central-south portion of the Amapa State, Brazil. The processing of the geophysical data yielded maps of magnetic lineaments and magnetic and gamma-spectrometric domains, from which new litho-geophysical units were recognized and previously mapped units were redefined (e.g., enderbitic bodies, mafic-ultramafic complexes and granitic intrusives). The magnetic structures are multi-oriented. The extensive Alto Cupixi Jari lineament shows prominently in the magnetic maps, separating the Cinturao Jari and the Atingo-Cupixi-Tartarugal Grande terranes. The NNW-trending structures appear ubiquitously in these maps and are often associated to gold mineralizations in the region. The inputs maps for the modelling process were geological and airbone geophysical data and gold in stream sediments. The results, using weights of evidence, artificial neural networks and fuzzy logic, show that Amapari deposits were classified as a hight potential site as expected and, most importantly, new targets with similar signatures were identified throughout the area. These new targets were validated in the field and using maps of detail geochemical anomalies for Au in the soil, generated by the MPBA. The areas identified by the spatial modeling methods are in agreement with the main geochemical anomalies, demonstrating that the determination of new potential targets based on indirect methods is consistent with the prospecting through direct methods
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências
8
Chanderman, Lisa. "Application of stochastic orebody simulation techniques to assess geological volume and grade uncertainty for gold reef deposits". Thesis, 2017. http://hdl.handle.net/10539/23453.
Abstract (sommario):
A Dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the Degree of Masters in Engineering by research only and to the Stochastic Mine Planning Laboratory, McGill University as part of the COSMO scholarship in Mine Planning under uncertainty
Johannesburg, 2017This dissertation discusses the use of stochastic orebody modelling techniques for assessing geological uncertainty associated with gold mineralisation at Geita Gold Mine in Tanzania, and proposes a practical methodology that can be applied to similar studies. As part of the pre-feasibility stage studies for underground mining at Geita, stochastic simulations were required to assess the geological uncertainty associated with isolating (modelled) high grade lenses that occur within the known low grade mineralisation currently targeted for underground mining. Two different simulation techniques are applied in this research: Sequential Indicator Simulation to generate lithofacies realisations from which to assess ore category boundaries and shapes for use in quantifying volumetric uncertainty; and Direct Block Simulations to simulate gold grade realisations from which to assess grade uncertainty. This study identified potential upside and downside mine planning scenarios for volumes and total metal content from the ore category and grade simulations respectively. The findings of the results demonstrated that the high grade zones are much more broken up and discontinuous than the currently modelled high grade shape. The current business case uses a probabilistic high grade shape based on a single grade indicator and a probability choice of 50 percent as the threshold for high grade. The results of the study consider a simulation of possible outcomes based on the same threshold grade indicator and hence quantify the uncertainty or total geological risk. This geological risk may be introduced to mine designs, production schedules and NPV predictions The stochastic workflow developed can be applied to analogous deposit types to assess the risk related to geological uncertainty. The work includes a description of practical considerations to be accounted for when applying the techniques.
MT 2017
9
Ismail, Roniza. "Spatial-temporal evolution of skarn alteration in IOCG systems: evidence from petrography, mineral trace element signatures and fluid inclusion studies at Hillside, Yorke Peninsula, South Australia". Thesis, 2016. http://hdl.handle.net/2440/112582.
Abstract (sommario):
Hillside is a newly-discovered, undeveloped copper resource related to Mesoproterozoic Hiltaba Suite intrusives along the crustal-scale Pine Point fault on the eastern margin of the Yorke Peninsula, South Australia. Mineralogical and petrographic study was undertaken on ~100 samples representative of all lithologies, parts of the deposit, and evolution from magmatic through prograde and retrograde skarn to late-stage hydrothermal overprint. Emphasis was placed on distributions of REE+Y and other trace elements in main minerals, and on the constraints these patterns provide for processes associated with alteration and mineralization. Alteration at Hillside is defined by diverse skarn assemblages. Most are readily interpreted as exoskarns formed onto (Moonta-Wallaroo Group) sedimentary protoliths. Two granitoids and associated pegmatites are indicative of composite (multiphase?) felsic magmatism. Granitoid emplacement and alkali-metasomatism pre-date skarn formation; the same initial alteration is recorded in coeval gabbros. The main prograde and retrograde associations [garnetite, garnet-(epidote-allanite-(Ce)) skarn, garnet-feldspar skarn and (pyroxenedominant) multi-component skarn] are defined by mineral associations and replacement relationships among calc-silicates and replacement of calc-silicates by secondary calcite±quartz±chlorite assemblages. Andradite-dominant garnet and diopside-dominant pyroxene are prograde minerals in this (magnetite-pyrite stable) association. Clinozoisite and amphibole are retrograde and co-exist with sulphides. Hematite-chalcopyrite+pyrite assemblages and advanced replacement of skarn minerals by calcite+quartz are associated with the late-retrograde stage. Skarnoid, at the skarn margin, contains the main skarn minerals, feldspars, grossular-rich garnet and minor wollastonite. LA-ICP-MS trace element datasets show that skarn minerals are rich in REY, Sn, HFSE and incompatible elements. Temporal (prograde-to-retrograde) evolution is recognised in terms of chondrite-normalised REY fractionation trends for garnet, with predictable patterns from sample to sample. Trace element concentrations in garnet represent the best guide to deposit-scale zonation patterns: Sn increases in garnet from N to S, and ΣREY increases from E to W. Trends for retrograde garnet are more varied, attributable to cycles of replacement, overgrowth and recrystallization. Nanoscale FIB-SEM-TEM investigation of feldspar and garnet allows distinction of whether key trace elements are lattice-bound or occur as nanoscale mineral inclusions. Preliminary fluid inclusion data provide evidence for early high-T, high-salinity fluids (~23 wt.% NaCl equiv., ~600 ºC, ~2 kbar) and the destructive influence of retrogression and reaction with later fluids tied to skarn collapse during uplift/fault reactivation (~1 wt.% NaCl equiv., <300 ºC, ~0.15 kbar). The study shows the potential value of LA-ICP-MS trace element signatures in garnet and accessories as petrogenetic tools and, potentially, as exploration vectors. The extraordinary petrographic and geochemical complexity implies that routine application of these patterns as an exploration tool is dependent upon recognition of underlying trends specific to protolith and spatial-temporal evolution. Hillside is defined as a Fe-Cu-(Au)-skarn that includes key features of an IOCG system. The deposit formed in a deep skarn setting (~6 km) and records a late-stage overprint during uplift and fault reactivation. The data can underpin sustainable genetic models for the Hillside deposit and contribute towards a metallogenic framework for the Olympic Cu-Au province, particularly with respect to the diversity of mineralization styles as an expression of ore formation at different crustal levels.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2016.
10
Downes, Peter M. "Sulfur- and lead-isotope signatures of selected middle Silurian to Carboniferous mineral systems of the Lachlan Orogen, eastern New South Wales - implications for metallogenesis". Thesis, 2009. http://hdl.handle.net/1959.13/916207.
Abstract (sommario):
Research Doctorate - Doctor of Philosophy (PhD)Sulfur- and lead-isotope signatures for 64 deposits/systems located in the Central and Easternn Subprovinces of the Lachlan Orogen in eastern New South Wales were characterised in the present study. Here are presented four new ⁴⁰Ar/³⁹Ar dates, 644 new sulfur- and 105 new leadisotope analyses, plus a collation of 386 unpublished and 277 published sulfur isotope and over 560 unpublished and published lead isotope analyses for middle Silurian to Early Carboniferous mineralisation. Measured δ³⁴S values for 22 VHMS deposits range between -7.4‰ to 38.3‰. S-isotope values for Currawang East, Lewis Ponds, Mount Bulga, Belara and Accost (Group 1) range from - 1.7‰ to 5.9‰ with the ore-forming fluids for this group of deposits likely to have been reducing and sulfur derived largely from magmatic sources. By contrast, S-isotope signatures for sulfides from Black Springs, Calula, Captains Flat, Commonwealth, Cordillera, Gurrundah, Kempfield, Peelwood mine, Sunny Corner, The Glen, Wet Lagoon and Woodlawn (Group 2) have average δ³⁴S values between 5.4‰ and 8.1‰. These deposits appear to have formed from ore fluids that were more oxidising than those for Group 1 deposits, representing a mixed contribution of sulfur derived from partial reduction of seawater sulfate, in addition to sulfur from other sources. Four deposits, Elsinora, John Fardy, Mount Costigan and Stringers, have heavier average δ³⁴S signatures (10.1‰ to 13.2‰) than Group 2 deposits, suggesting that these deposits included a greater component of sulfur of seawater origin. The S-isotope data for barite from Black Springs, Commonwealth, Stringers, Gurrundah, Kempfield and Woodlawn range from 12.6‰ to 38.3‰. Over 80% of the δ³⁴S values are between 23.4‰ and 30.9‰, close to the previously published estimates for the composition of seawater sulfate during Late Silurian to earliest Devonian times, providing supporting evidence that these deposits formed concurrently with a Late Silurian volcanic event. New Pb isotope data for eleven VHMS deposits included in the present study support earlier Pb-isotope studies which indicate that lead was largely sourced from the host sequence. However, the data for Black Springs, Elsinora and Commonwealth indicate that some lead, included in these deposits, was sourced from units forming basement to the Silurian troughs. Sulfur isotope values for thirteen orogenic gold systems range between -7.5‰ and 16.1‰ (excluding outliers). The Wyoming One–Myall United system has an average δ³⁴S value of -5.5‰ and a primitive mantle-derived lead isotope signature implying that sulfur and gold were sourced from a fractionated mantle-derived intrusion. The δ-isotope data for Adelong, Bodangora, Calarie, Hargraves, Hill End, London–Victoria, Sebastopol, Sofala–Wattle Flat and Stuart Town are all very similar with average δ³⁴S values close to 0‰ (range -2.8 to 3.4‰). Sulfur in these deposits was derived from reduced fluids, sources from magmatic reservoirs either as a direct input or through dissolution and recycling of rock sulfide. For deposits hosted by the northern HET it is suggested that sulfur and gold were sourced from mantle-derived units located beneath the HET rather than the siliclastic fill of the trough itself. Windeyer and Napoleon Reefs have heavier S-isotope signatures suggesting a greater contribution of sulfur derived from reduced seawater sulfate reservoirs. Springfield, located adjacent to the northern HET, has the heaviest S-isotope signature (15.4 δ³⁴S‰) for orogenic gold deposits included in the present study. For this deposit it is suggested that HET-derived basinal fluids containing reduced seawater sulfate migrated along faults and leached gold from Ordovician mantle-derived units forming basement to that area. Seven sulfide-rich orogenic base metal deposits were included in the present study. Average δ³⁴S values for Currawang South, Frogmore, Montrose, Ruby Creek, Wallah Wallah vary between 3.5‰ and 6.0‰ (Group 1), with Kangiara, and Lucky Hit–Merrilla, having heavier average δ³⁴S values (10.0‰ and 8.2‰ respectively — Group 2). Group 1 deposits are small, and S-isotope signatures suggest significant sulfur was sourced from magmatic reservoirs; whereas, Group 2 deposits are larger and δ³⁴S signatures indicate a larger component of sulfur was derived from reduced seawater sulfate reservoirs. The Pb-isotope data for these deposits suggest that the majority of the lead was derived from older Ordovician and Silurian crustal reservoirs. The data for Mount Werong and Merrilla support a Middle Devonian Pb-model age; whereas, those for Wallah Wallah point to an Early Carboniferous Pb-model age. Browns Reef, in the Central Subprovince, is now interpreted to be a syn-deformational orogenic base metal deposit, for which the S-isotope data are similar to Group 2 orogenic base metal deposits and Pb-isotope data suggest lead was sourced from the fill of the Rast Trough. Five epithermal systems were included in the present study. Bauloora, Bowdens and those in the Yerranderie district are intermediate-sulfidation epithermal systems; whereas, Yalwal and Pambula are low sulfidation epithermal systems. Yerranderie, Yalwal, Pambula and Bauloora have δ³⁴S values close to 0‰. Sulfur in these deposits was derived largely from a magmatic reservoir. The Yerranderie system is zoned with respect to S-isotope distribution and shows mineralogical zonation along the Yerranderie Fault. Yalwal is zoned with 0‰ S-isotope values correlating with sericitic alteration assemblages and heavier S-isotope values (up to 17.9 δ³⁴S‰) correlating with assemblages that include minerals characteristic of argillic alteration. Sixteen middle Silurian to Early Devonian intrusion-related deposits were included in the present study. Collector, Dargues Reef, Mayfield, Ryans, Tallawang, Whipstick and Yambulla are located east of the I–S granite line, with Dargues Reef, Majors Creek, Mayfield, Whipstick and Yambulla hosted by or adjacent to their causative intrusion. These deposits have S-isotope signatures close to 0‰ (range -3.6‰ to 3.0‰) similar to that for granites east of the I–S line (range -1.5‰ to 4.9‰). The Pb-isotope data for these deposits includes both crustal- and mantle-derived lead. Deposits distal to their causative intrusions (Collector and Ryans) have heavier S-isotope signatures (7.7‰ and 4.3‰ respectively) indicating that some sulfur was probably sourced from the host sequence. The majority of lead, for these deposits, was sourced from the host sequence and/or older reservoirs. The S-isotope data for Tallawang suggest that the sulfur was largely sourced from the host sequence. Eight deposits are located to the west of the I–S line. Nasdaq, Phoenix, Tara, Rye Park and Mineral Hill have heavier S-isotope signatures (range: 2.6‰ to 7.3‰) which overlap with the range of values typical of granites located to the west of the I–S line (1.9 to 9.6‰) supporting the interpretation that the majority of sulfur was derived from the causative intrusion. The Pb-isotope data for Nasdaq, Mineral Hill and Tara suggest that lead originated from the host sequence or from older lead reservoirs; whereas, at Rye Park and Phoenix lead was probably sourced from the causative intrusion. Ardlethan and Browns Creek deposits have near 0‰ S-isotope signatures, lower than the range of δ³⁴S values for granites west of the I–S line which is accounted for by mantle-derived volatiles and a possible biogenic sulfur component. The Pb-isotope data for these two deposits are consistent with a lead sourced largely from the causative intrusion; although, some mantlederived lead is probably present. Red Hill has the highest S-isotope signature (13.7‰) indicating that the majority of sulfur was sourced from a seawater sulfate reservoir. ⁴⁰Ar/³⁹Ar dating showed that intrusion-related mineralisation at Tara formed at 420 ± 2 Ma; VHMS-related mineralisation at The Glen (Glen E deposit) formed at 418.2 ± 2.2 Ma; and that the Yerranderie and Bauloora intermediate sulfidation epithermal systems formed at 372.1 ± 1.9 Ma and 371 ± 13 Ma (respectively). New dating plus a review of timing constraints to Tabberabberan and Kanimblan cycle-related mineralisation highlighted metallogenic events at ~430 Ma (intrusion-related), ~420 Ma (intrusion- and VHMS-related) and a mid Devonian epithermal event. The timing of orogenic-related mineralisation is diachronous across the study area with the majority of orogenic gold systems in the west forming during the Middle Devonian Tabberabberan Orogeny; whereas, similar mineralisation in the northern HET formed during the Early Carboniferous Kanimblan Orogeny.
Libri sul tema "Gold mineral system":
1
K, Foley N., a cura di. Mineralogy, mineral chemistry, and paragenesis of gold, silver, and base-metal ores of the North Amethyst vein system, San Juan Mountains, Mineral County, Colorado. Washington: U.S. G.P.O., 1993.
2
R, Brooks R., a cura di. Noble metals and biological systems: Their role in medicine, mineral exploration, and the environment. Boca Raton: CRC Press, 1992.
3
V, Tingley Joseph, e Bonham H. F, a cura di. Precious-metal mineralization in hot springs systems, Nevada-California. Reno, Nev: University of Nevada-Reno, Mackay School of Mines, 1986.
4
Brooks, Robert R. Noble Metals and Biological Systems: Their Role in Medicine, Mineral Exploration, and the Environment. CRC, 1992.
5
Levy, Norman. Foundations of the South African Cheap Labour System. Taylor & Francis Group, 2022.
6
Levy, Norman. Foundations of the South African Cheap Labour System. Taylor & Francis Group, 2022.
7
Contrasting styles of intrusion-associated hydrothermal systems. Littleton, CO: Society of Economic Geologists, 2000.
8
Levy, Norman. Foundations of the South African Cheap Labour System. Routledge, Chapman & Hall, Incorporated, 2022.
9
Levy, Norman. Foundations of the South African Cheap Labour System. Taylor & Francis Group, 2022.
10
Dilles, J. H. Guidebook 32: Part I. Contrasting Styles of Intrusion: Associated Hydrothermal Systems; Part II. Geology and Gold Deposits of the Getchell Region. Economic Geology Pub Co, 2004.
Capitoli di libri sul tema "Gold mineral system":
1
Espi, Joseph O., Ken-ichiro Hayashi, Kosei Komuro, Yoshimichi Kajiwara e Hiroyasu Murakami. "The Bilimoia gold deposit, Kainantu, Papua New Guinea: A fault-controlled, lode-type, synorogenic tellurium-rich quartz-gold vein system". In Mineral Deposit Research: Meeting the Global Challenge, 941–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_240.
2
Chelle-Michou, Cyril, e Urs Schaltegger. "U–Pb Dating of Mineral Deposits: From Age Constraints to Ore-Forming Processes". In Isotopes in Economic Geology, Metallogenesis and Exploration, 37–87. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_3.
Abstract (sommario):
AbstractThe timing and duration of ore-forming processes are amongst the key parameters required in the study of mineral systems. After more than a century of technical developments, innovations and investigation, the U–Pb system arguably is the most mature radioisotopic system in our possession to conduct absolute dating of a wide range of minerals across geological environments and metallogenic processes. Here, we review the basics of U–Pb geochronology, the key historic developments of the method, and the most commonly used analytical techniques (including data reduction, Pb-correction, uncertainty propagation and data presentation) and minerals while pointing out their respective advantages, weaknesses and potential pitfalls. We also highlight critical aspects that need to be considered when interpreting a date into the age of a geological process (including field and petrographic constraints, open-system behavior, handling and interpretation of uncertainties). While U–Pb geochronology is strongly biased toward zircon dating, we strive to highlight the great diversity of minerals amenable to U–Pb dating (more than 16 mineral species) in the context of mineral systems, and the variety of geological events they can potentially date (magmatism, hydrothermal activity, ore-formation, cooling, etc.). Finally, through two case studies we show (1) how multi-mineral geochronological studies have been used to bracket and decipher the age of multiple geological events associated with the world-class Witwatersrand gold province, and (2) how rather than the absolute age, the duration and rate of the mineralizing event at porphyry copper deposits opens new avenues to understand ore-forming processes and the main controls on the size of such deposits. The improving precision, accuracy and spatial resolution of analyses in tandem with high-quality field and petrographic observations, numerical modelling and geochemical data, will continue to challenge paradigms of ore-forming processes and contribute significant breakthroughs in ore deposit research and potentially to the development of new exploration tools.
3
Zeng, Q. D., J. M. Liu, H. T. Liu, G. M. Li, T. B. Liu, C. M. Yu, P. Shen e J. Ye. "Application of the EH4 image system to the detection of blind gold deposits, China". In Mineral Deposit Research: Meeting the Global Challenge, 1505–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_383.
4
Vos, I. M. A., e F. P. Bierlein. "Gold systems in northeastern Queensland: A key to tectonic evolution of the northern Tasman Fold Belt System, Australia". In Mineral Deposit Research: Meeting the Global Challenge, 593–96. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_152.
5
Drahota, P., e Z. Pertold. "Fluxes of arsenic in soil-water system in the Celina-Mokrsko gold district, Bohemian Massif". In Mineral Deposit Research: Meeting the Global Challenge, 927–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_236.
6
Bouabdellah, M., F. Chekroun, A. Alansari e D. Margoum. "The Granitoid-Related Tiouit Gold Deposit, Saghro Inlier, Eastern Anti-Atlas (Morocco): Neoproterozoic Mineralization by a Polyphase Late-Magmatic to Hydrothermal System". In Mineral Deposits of North Africa, 405–14. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31733-5_16.
7
Quesnel, Benoît, Christophe Scheffer e Georges Beaudoin. "The Light Stable Isotope (Hydrogen, Boron, Carbon, Nitrogen, Oxygen, Silicon, Sulfur) Composition of Orogenic Gold Deposits". In Isotopes in Economic Geology, Metallogenesis and Exploration, 283–328. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_10.
Abstract (sommario):
AbstractOrogenic gold deposits formed in various terranes of most ages since the Paleoarchean and generally consist of quartz veins hosted in shear zones formed at the ductile brittle transition under greenschist to lower amphibolite metamorphic conditions. Vein mineralogy is dominated by quartz with various amounts of silicates, carbonates, phyllosilicates, borates, tungstates, sulfides, and oxides. The isotopic composition of these minerals and fluid inclusions has been investigated since the 1960s to constrain the characteristics of orogenic fluid systems involved in the formation of gold deposits worldwide. This review is based on 8580 stable isotope analyses, including δ18O, δD, δ13C, δ34S δ15N, δ11B, and δ30Si values, from 5478 samples from 558 orogenic gold deposits reported in the literature from 1960 to 2010. This contribution describes the variability of the light stable isotopic systems as function of the minerals, the age of the deposits, their regional setting, and their country rocks. The temperature of isotopic equilibrium of orogenic gold veins is estimated from mineral pairs for oxygen and sulfur isotopes. Based on these temperatures, and on fractionation between mineral and fluid components (H2O, CO2 and H2S), the isotopic composition of fluids is estimated to better constrain the main parameters shared by most of auriferous orogenic fluid systems. Orogenic gold deposits display similar isotopic features through time, suggesting that fluid conditions and sources leading to the formation of orogenic gold deposits did not change significantly from the Archean to the Cenozoic. No consistent secular variations of mineral isotope composition for oxygen (−8.1‰ ≤ δ18O ≤ 33‰, n = 4011), hydrogen (−187‰ ≤ δD ≤ −4‰, n = 246), carbon (−26.7‰ ≤ δ13C ≤ 12.3‰, n = 1179), boron (−21.6‰ ≤ δ11B ≤ 9‰, n = 119), and silicon (−0.5‰ ≤ δ30Si ≤ 0.8‰, n = 33) are documented. Only nitrogen (1.6‰ ≤ δ15N ≤ 23.7‰, n = 258) and sulfide sulfur from deposits hosted in sedimentary rocks (−27.2‰ ≤ δ34S ≤ 25‰, n = 717) display secular variations. For nitrogen, the change in composition is interpreted to record the variation of δ15N values of sediments devolatilized during metamorphism. For sulfur, secular variations reflect incorporation of local sedimentary sulfur of ultimate seawater origin. No significant variation of temperature of vein formation is documented for orogenic gold deposits of different ages. Quartz-silicate, quartz-carbonate and sulfide-sulfide mineral pairs display consistent temperatures of 360 ± 76 °C (1σ; n = 332), in agreement with the more common greenschist facies hostrocks and fluid inclusion microthermometry. Fluid sources for orogenic gold deposits are complex but the isotopic systems (hydrogen, boron, carbon, nitrogen, oxygen, sulfur) are most consistent with contributions from metamorphic fluids released by devolatilization of igneous, volcano-sedimentary and/or sedimentary rocks. The contribution of magmatic water exsolved from magma during crystallization is not a necessary component, even if permissible in specific cases. Isotopic data arrays can be interpreted as the result of fluid mixing between a high T (~550 °C)—high δ18O (~10‰)—low δD (~−60‰) deep-seated (metamorphic) fluid reservoir and a low T (~200 °C)—low δ18O (~2‰)—high δD (~0‰) upper crustal fluid reservoir in a number of orogenic gold deposits. The origin of the upper crustal fluid is most likely sea- or meteoric water filling the host rock porosity, with a long history of water–rock isotope exchange. Mixing of deep-seated and upper crustal fluids also explains the large variation of tourmaline δ11B values from orogenic gold veins. Regional spatial variations of oxygen and hydrogen isotope compositions of deep-seated fluid reservoirs are documented between orogenic gold districts. This is the case for the Val-d’Or (Abitibi), Coolgardie and Kalgoorlie (Yilgarn) where the oxygen isotope composition of the deep-seated fluid end-member is 4‰ lower compared to that from the Timmins, Larder Lake, and Kirkland Lake districts (Abitibi). However, both mixing trends converge towards a common, low δ18O upper crustal fluid end-member. Such variations cannot be related to fluid buffering at the site of deposition and suggest provinciality of the fluid source. The contribution of meteoric water is mainly recorded by fluid inclusions from Mesozoic and Cenozoic age deposits, but micas are not systematically in isotopic equilibrium with fluid inclusions trapped in quartz from the same vein. This suggests late involvement of meteoric water unrelated to deposit formation. Yet, a number of deposits with low δD mica may record infiltration of meteoric water in orogenic gold deposits. Isotope exchange between mineralizing fluid and country rocks is documented for oxygen, carbon, sulfur and silicon isotopes. Large variations (> 10‰) of sulfide δ34S values at the deposit scale are likely related to evolving redox conditions of the mineralizing fluid during reaction with country rocks. Deposits hosted in sedimentary rocks show a shift to higher δ18O values as a result of fluid/rock oxygen exchange with the regional sedimentary country rocks.
8
McCulloch, Jock, e Pavla Miller. "Conclusion: Records, Bodies and Contested Justice". In Mining Gold and Manufacturing Ignorance, 403–28. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8327-6_15.
Abstract (sommario):
AbstractThe conclusion draws together the main themes of the book and brings the story of the miners’ class action up to date.For most of the twentieth century, gold mining dominated South Africa’s economy. Through their extensive use of migrant labour, the industry helped shape the economies—and populations—of the southern half of the continent. The mines led the world in the use of science, provisions for compensating occupational injury and state oversight of the industry. Yet their reputation for excellence was undeserved. Rather, the collusion between the state and the industry in suppressing the knowledge of risk, the publication of misleading data and the use of publicity is best characterised as the manufacture of ignorance. In particular, the systematic failure to collect health statistics and employment records impeded the accumulation of comparable data, prevented the consolidation of epidemiological evidence and so played a significant part in hiding an epidemic of occupational lung disease.In the first half of the twentieth century, the South African gold mining industry helped shape and consolidate apartheid. The gradual dismantling of this system in the 1990s presented both the industry and social justice advocates with far-reaching challenges. The recent settlement of the miners’ class action and establishment of the Tshiamiso Trust coincided with sharp decline of the gold mining industry and struggling ODMWA compensation system. Lack of administrative capacity, patchy employment records, difficulties in diagnosing silicosis and TB and shortages of medical staff have been exacerbated by the COVID pandemic. These and other issues have become the focus of a Justice for Miners campaign. The chapter concludes by noting that those who support miners injured in South Africa’s process of wealth accumulation—propose solutions to practical problems, conduct research into occupational diseases and mobilise local communities—make a double contribution to social justice. They assist miners and their families receive compensation, and help heal longstanding injuries to the region’s civil society.
9
Baker, T., e C. Ryan. "PIXE analysis of contrasting fluid inclusion types in intrusion-related gold systems of the Tintina Gold Province, Yukon, Alaska". In Mineral Deposit Research: Meeting the Global Challenge, 877–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27946-6_223.
10
McCulloch, Jock, e Pavla Miller. "Identifying Risk and Compensating Tuberculosis: 1916–1957". In Mining Gold and Manufacturing Ignorance, 83–110. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8327-6_4.
Abstract (sommario):
AbstractDriven by concerns of the white Mine Workers Union, South Africa was the first state to compensate for silicosis and tuberculosis as occupational diseases. The Acts were woven around the binary pairing of miners (whites) and native labourers (blacks). That device enabled legislators to racialise the labour laws without mentioning race. This chapter traces the development of thorough medical examinations, comprehensive health care and a generous compensation system for whites, alongside a system designed to prevent the employment of men who already developed lung disease and to minimise compensation for the (black) majority of the workforce. Having reluctantly agreed to compensate tuberculosis, the Chamber of Mines was relentless in opposing the many critics who argued that the mines were a source of infection. As the critics reiterated, dust exposure created a pool of infected men who were repatriated to rural areas where little or no biomedical care was available. The low wages offered by the mines impoverished labour-sending communities, and this in turn created the ideal social setting for infection to take hold and to spread. Finally, because most infected miners did not receive compensation, their home communities were further impoverished by having to care for men who were no longer able to work.
Atti di convegni sul tema "Gold mineral system":
1
Hancock, Elena. "Microstructure of gold as a record of mineral system evolution". In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.10091.
2
Fadillah, Taruna, Sugiyanto, Abdurrahman Nasrudin e Satria Rum Syachran. "Optimizing maximum unsupported span value by Q - system to enhance production in mining operation, case study Antam Pongkor underground gold mine". In 2ND INTERNATIONAL CONFERENCE ON EARTH SCIENCE, MINERAL, AND ENERGY. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0006844.
3
Batugina, N. S., e E. A. Khoiutanov. "NORTH EASTERN YAKUTIA GOLD MINERAL RAW MATERIAL BASE: ANALYSIS, EVALUATION AND PROSPECTS". In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s03.45.
Abstract (sommario):
The paper presents a detailed review of ore and alluvial gold mineral raw material base of North East of Yakutia and estimates the economic efficiency of development of gold deposits not involved in the exploitation. Research methods: analysis and comparison, qualitative and quantitative features of the mineral raw material base of Yakutia, formed and replenished databases on a number of deposits of the region; methods of analogy, economic-statistical, methods of system analysis and decision support, evaluation of efficiency of development of deposits. The article provides a detailed analysis of the distributed and undistributed fund of ore and placer gold deposits and shows that the level of the distributed fund is quite high. It is noted that there are certain reserves of a promising and developed gold raw material base in the North-East of Yakutia. The authors identify factors that reduce the efficiency of development of the mineral resource base of gold in the North-East of Yakutia: territorial separation, location in areas with weak or absent infrastructure, availability, for the most part, of small and medium-sized stocks at high levels. The article shows that objects of ore and placer gold due to the complexity of geological and industrial types of objects have increased operating and capital costs and infrastructure limitations. This article presents the authors' developed set of geotechnological and economic measures that can increase the efficiency of the exploited deposits, involve in the development of small and medium-sized gold ore objects. The article provides the calculations which show that the mineral raw material base of ore and placer gold of the North-Aast of the Republic of Sakha (Yakutia) is sufficient to maintain the annual metal production at more than 20 tons per year, and the raw material potential of this region enhances to increase this level for a long time with appropriate investments in geological exploration. The assessment of economic efficiency confirms that the introduction of gold ore and placer deposits in the North-East of Yakutia to the economic circulation generates substantial income to investors and create new jobs.
4
Espinasse, Philippe. "Deepsea Pilot SMS Mining System for Harsh Environments". In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20477.
Abstract (sommario):
Following the trend of oil and gas production in deep waters, ore mining is about to start in the deep waters of the Pacific Ocean. If the first system will most probably be installed in the quiet though deep waters of Papua New Guinea, other prospects lie in the more turbulent areas of New Zealand and the Tongas. The ore accumulations to be mined are high grade hydrothermal mineral deposits rich in copper, gold, zinc, lead and silver located directly on the seabed. However, the excavation techniques need to be quite different from what had been envisaged for manganese nodules due to the morphology of the deposits. Based on its deep water construction experience, Genesis France, a company of the Technip Group has been contracted to perform a screening study of the various technologies to be applied to cut, crush, lift to the surface and pre-process the massive seabed sulphide deposits in a safe, efficient and profitable manner while minimizing the environmental impact of such work. This paper presents the conceptual screening study, the systems that have been evaluated, the selection criteria and the resulting operating system.
5
McConnell, D. R. "Prospects for Marine Minerals in the US Pacific OCS and EEZ". In Offshore Technology Conference. OTC, 2024. http://dx.doi.org/10.4043/35266-ms.
Abstract (sommario):
Abstract The seafloor in the US Pacific OCS and EEZ is enriched to varying degrees in critical and economically important minerals such as nickel, manganese, cobalt, copper, zinc, REY (rare earth elements plus yttrium), titanium, vanadium, antimony, gold, and silver. These mineral deposits take the form of polymetallic nodules on the seabed, cobalt rich ferromanganese crusts on seamounts and ridges swept clean of sediment accumulation, and seafloor massive sulfides formed by hydrothermal systems at geologic plate spreading centers and volcanic margins. Each of these mineral deposits form on or near the deep ocean seafloor where water depths are typically 4000 m to 5500 m and on the seamounts and volcanic arcs that rise from these depths. Commercial interest in deep sea mineral deposits and the potential for collecting or mining them began in earnest in the 1970s but has been heightened in the last 20 years as the international framework for developing these minerals in International Waters has matured that has coincided with forecasted rapid rising demand for minerals to supply energy and manufacturing needs for the green economy. Compilation reports published by academia, government, and private companies are reviewed to assemble data and assess the prospects for deep sea marine minerals in the US Pacific OCS and EEZ. Key compilations were made by the Circum-Pacific Council and USGS in the 1980s and 1990s. These, together with recent (2023) efforts by USGS to compile geochemical data from USGS affiliated marine research sampling cruises from the 1980s and 1990s, historical data maintained by NOAA National Centers for Environmental Information (NCEI), and recent publicly disclosed results from ISA contractors are used to inform the known occurrence and prospectivity for polymetallic nodules, cobalt-rich ferromanganese crusts, and seafloor massive sulfides in the US Pacific OCS and EEZ.
6
Okada, K., Y. Minami e M. Ono. "Microtremor Survey for Exploration Targetting Epithermal Vein Systems at the Hishikari Gold Mine, Kagoshima, Japan". In 2nd Conference on Geophysics for Mineral Exploration and Mining. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201802740.
7
Umarbekova, Z. �., A. A. Antonenko, M. A. ��shrapova, Sh D. �iniskul e D. Shamsutdin. "DYNAMICS OF ORE-FORMING PROCESSES IN CASE OF KAZAKHSTAN�s GOLD ORE DEPOSITS". In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s01.03.
Abstract (sommario):
The paper considers processes of ore formation. This concerns complex dynamic natural objects, depending on polygenic geological phenomena, mutually interacting and forming a single mineral formation environment. Development of ore-forming systems is connected not only with the natural evolution of thermodynamic parameters, but also with physical-chemical properties and composition of ore-bearing deposits, state and character of manifestation of tectonic structures, such as field strength, degree of tectonic transformation of rocks, dynamometamorphism and others. Influence of postmagmatic fluids and other factors on the process of mineral formation is also considered. Mineral formation at gold deposits is the result of the interaction of various polygenic geological processes that ultimately determine the character of mineralisation at the deposits. Experimental studies cannot fully reconstruct the conditions of ore formation. Therefore, it is necessary to apply the method of recalculation of thermodynamic constants.
8
Danyushevsky, L., P. Farias, J, Whelan, B. Reno, A. Cross, D. Huston, R. Maas e T. Mernagh. "Base Metal Mineralisation of the Rover Field, Northern Territory". In Central Australian Basins Symposium IV. Petroleum Exploration Society of Australia (PESA), 2022. http://dx.doi.org/10.36404/jpgc5409.
Abstract (sommario):
The Warramunga Province of the Palaeoproterozoic North Australian Craton, in the central Northern Territory, represents a prospective terrane for mineral exploration. A well-known example is the Tennant Creek mineral field, which has a rich history of gold, copper, bismuth, silver, and selenium production. Some 80 km southwest of the Tennant Creek mineral field is the entirely undercover Rover field, which hosts base and precious metal deposits with established mineral resources (JORC). Despite this, the geological framework, nature and timing of mineral systems remains poorly understood.
9
Stanišić, Tijana, Nataša Karić, Milica Karanac, Maja Đolić, Mirjana Ristić e Aleksandra Perić-Grujić. "Natural Adsorbents Based on Metal Oxide Structures for Removal of Lead And Arsene Ions from Aqueous Solution". In 34th International Congress on Process Industry. SMEITS, 2021. http://dx.doi.org/10.24094/ptk.021.34.1.43.
Abstract (sommario):
The aim of this research is to examine the efficiency of raw mineral materials that possess good adsorption and techno-economic properties applicable in real systems for the removal of heavy metal ions, primarily lead and arsenic. The adsorption studies were conducted in batch system. To determine the optimal conditions, the adsorption efficiency of the selected ions was tested by variation of the adsorbents mass (5, 7.5, 10 and 20 mg). The materials used in the experimental work are of mineral origin, whose composition consists mainly of SiO2, Al2O3 and Fe2O3. The characterization of analyzed materials was performed using X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). The maximum removal efficiency of lead ions is 94.8 %, on the material predominantly composed of loam, while for arsenic it is 47.5 % on material based on sandy loam.
10
Bondaryeva, Аnna, Maryna Zhaldak, Оlena Mokrousova e Olena Okhmat. "Nanopigments for Leather Finishing Coatings". In The 9th International Conference on Advanced Materials and Systems. INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania, 2022. http://dx.doi.org/10.24264/icams-2022.i.4.
Abstract (sommario):
The work is focused on obtaining nanopigments by adsorption of anionic dyes on positively charged montmorillonite. The effect of sequential modification of aqueous dispersions of montmorillonite with cationic and anionic compounds on the structural and charge characteristics of mineral dispersions was studied. The effect of chemical dispersion of agglomerates of aqueous montmorillonite dispersions after adding carbonate solutions was shown. The treatment of dispersions of original montmorillonite with sodium carbonate provides maximum dispersion of mineral aggregates by penetrating into the interstructural space of aluminosilicate packets, moving them apart and separating them. It was found that the modification of montmorillonite dispersed by sodium carbonate by adding basic chromium sulfate is accompanied by a change in the surface chemistry of the mineral and structural transformations. Structural changes are manifested by the formation of a developed structure of cationic montmorillonite. The cationic surface charge of montmorillonite and high specific surface of montmorillonite are important factors for ensuring effective adsorption of anionic dyes on the surface of the mineral. The efficiency of adsorption of anionic dyes on cationic montmorillonite is investigated. It was shown that the adsorption of dyes depended on the pH of the medium. The scheme of obtaining nanopigments, which were characterized by good сovering power, saturated and intense colour was proposed.
Rapporti di organizzazioni sul tema "Gold mineral system":
1
Corriveau, L., e E. G. Potter. Advancing exploration for iron oxide-copper-gold and affiliated deposits in Canada: context, scientific overview, outcomes, and impacts. Natural Resources Canada/CMSS/Information Management, 2024. http://dx.doi.org/10.4095/332495.
Abstract (sommario):
The Geo-mapping for Energy and Minerals (GEM) and Targeted Geoscience Initiative (TGI) programs conducted extensive collaborative research on mineral systems with iron oxide-copper-gold (IOCG) and affiliated deposits in prospective settings of Canada. Regional alteration mapping as well as geochemical and geophysical modelling undertaken under the GEM program documented the evolution of polymetallic metasomatic systems with iron-oxide and alkali-calcic alteration and led to an increased recognition of the mineral potential of poorly explored areas and historic deposits of the Great Bear magmatic zone in the Northwest Territories, thus providing a solid framework for exploration. Early and barren albitite corridors form across the mineral systems and locally host uranium mineralization associated with telescoping of alteration facies by tectonic activity during the metasomatic growth of the systems. Subsequent to albitization, high-temperature Ca-Fe and Ca-K-Fe alteration form iron oxide-apatite (± rare-earth element) mineralization and IOCG variants rich in cobalt and other critical metals, respectively. Systems that further mature to K-Fe alteration form IOCG mineralization and can evolve to mineralized near-surface phyllic alteration and epithermal caps. Transitional facies also host polymetallic skarn mineralization. Rare-earth element enrichments within iron oxide-apatite zones are strongest where remobilization has occurred, particularly along deformation zones. The TGI projects documented the pertinence for a GEM activity in the Great Bear magmatic zone and subsequently synthesized GEM geoscientific data into a system-scale, ore-deposit model, and outlined criteria for mineral resource assessment. This model, and newly developed field-mapping and lithogeochemical tools were shown to be efficient mineral exploration and regional mapping methods in Canada and were also applied to the archetype IOCG deposit, Olympic Dam, and other deposits in the Olympic Cu-Au metallogenic province of Australia. Case examples also include the Romanet Horst in the Trans-Hudson Orogen (second phase of GEM), the Central Mineral Belt in Labrador (TGI), the Wanapitei Lake district in Ontario (private sector exploration results used by TGI), and the Bondy gneiss complex in Quebec (TGI).
2
Corriveau, L., J. F. Montreuil, O. Blein, E. Potter, M. Ansari, J. Craven, R. Enkin et al. Metasomatic iron and alkali calcic (MIAC) system frameworks: a TGI-6 task force to help de-risk exploration for IOCG, IOA and affiliated primary critical metal deposits. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329093.
Abstract (sommario):
Australia's and China's resources (e.g. Olympic Dam Cu-U-Au-Ag and Bayan Obo REE deposits) highlight how discovery and mining of iron oxide copper-gold (IOCG), iron oxide±apatite (IOA) and affiliated primary critical metal deposits in metasomatic iron and alkali-calcic (MIAC) mineral systems can secure a long-term supply of critical metals for Canada and its partners. In Canada, MIAC systems comprise a wide range of undeveloped primary critical metal deposits (e.g. NWT NICO Au-Co-Bi-Cu and Québec HREE-rich Josette deposits). Underexplored settings are parts of metallogenic belts that extend into Australia and the USA. Some settings, such as the Camsell River district explored by the Dene First Nations in the NWT, have infrastructures and 100s of km of historic drill cores. Yet vocabularies for mapping MIAC systems are scanty. Ability to identify metasomatic vectors to ore is fledging. Deposit models based on host rock types, structural controls or metal associations underpin the identification of MIAC-affinities, assessment of systems' full mineral potential and development of robust mineral exploration strategies. This workshop presentation reviews public geoscience research and tools developed by the Targeted Geoscience Initiative to establish the MIAC frameworks of prospective Canadian settings and global mining districts and help de-risk exploration for IOCG, IOA and affiliated primary critical metal deposits. The knowledge also supports fundamental research, environmental baseline assessment and societal decisions. It fulfills objectives of the Canadian Mineral and Metal Plan and the Critical Mineral Mapping Initiative among others. The GSC-led MIAC research team comprises members of the academic, private and public sectors from Canada, Australia, Europe, USA, China and Dene First Nations. The team's novel alteration mapping protocols, geological, mineralogical, geochemical and geophysical framework tools, and holistic mineral systems and petrophysics models mitigate and solve some of the exploration and geosciences challenges posed by the intricacies of MIAC systems. The group pioneers the use of discriminant alteration diagrams and barcodes, the assembly of a vocab for mapping and core logging, and the provision of field short courses, atlas, photo collections and system-scale field, geochemical, rock physical properties and geophysical datasets are in progress to synthesize shared signatures of Canadian settings and global MIAC mining districts. Research on a metamorphosed MIAC system and metamorphic phase equilibria modelling of alteration facies will provide a foundation for framework mapping and exploration of high-grade metamorphic terranes where surface and near surface resources are still to be discovered and mined as are those of non-metamorphosed MIAC systems.
3
Neyedley, K., J. J. Hanley, Z. Zajacz e M. Fayek. Accessory mineral thermobarometry, trace element chemistry, and stable O isotope systematics, Mooshla Intrusive Complex (MIC), Doyon-Bousquet-LaRonde mining camp, Abitibi greenstone belt, Québec. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328986.
Abstract (sommario):
The Mooshla Intrusive Complex (MIC) is an Archean polyphase magmatic body located in the Doyon-Bousquet-LaRonde (DBL) mining camp of the Abitibi greenstone belt, Québec, that is spatially associated with numerous gold (Au)-rich VMS, epizonal 'intrusion-related' Au-Cu vein systems, and shear zone-hosted (orogenic?) Au deposits. To elucidate the P-T conditions of crystallization, and oxidation state of the MIC magmas, accessory minerals (zircon, rutile, titanite) have been characterized using a variety of analytical techniques (e.g., trace element thermobarometry). The resulting trace element and oxythermobarometric database for accessory minerals in the MIC represents the first examination of such parameters in an Archean magmatic complex in a world-class mineralized district. Mineral thermobarometry yields P-T constraints on accessory mineral crystallization consistent with the expected conditions of tonalite-trondhjemite-granite (TTG) magma genesis, well above peak metamorphic conditions in the DBL camp. Together with textural observations, and mineral trace element data, the P-T estimates reassert that the studied minerals are of magmatic origin and not a product of metamorphism. Oxygen fugacity constraints indicate that while the magmas are relatively oxidizing (as indicated by the presence of magmatic epidote, titanite, and anhydrite), zircon trace element systematics indicate that the magmas were not as oxidized as arc magmas in younger (post-Archean) porphyry environments. The data presented provides first constraints on the depth and other conditions of melt generation and crystallization of the MIC. The P-T estimates and qualitative fO2 constraints have significant implications for the overall model for formation (crystallization, emplacement) of the MIC and potentially related mineral deposits.
4
Neyedley, K., J. J. Hanley, P. Mercier-Langevin e M. Fayek. Ore mineralogy, pyrite chemistry, and S isotope systematics of magmatic-hydrothermal Au mineralization associated with the Mooshla Intrusive Complex (MIC), Doyon-Bousquet-LaRonde mining camp, Abitibi greenstone belt, Québec. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328985.
Abstract (sommario):
The Mooshla Intrusive Complex (MIC) is an Archean polyphase magmatic body located in the Doyon-Bousquet-LaRonde (DBL) mining camp of the Abitibi greenstone belt, Québec. The MIC is spatially associated with numerous gold (Au)-rich VMS, epizonal 'intrusion-related' Au-Cu vein systems, and shear zone-hosted (orogenic?) Au deposits. To elucidate genetic links between deposits and the MIC, mineralized samples from two of the epizonal 'intrusion-related' Au-Cu vein systems (Doyon and Grand Duc Au-Cu) have been characterized using a variety of analytical techniques. Preliminary results indicate gold (as electrum) from both deposits occurs relatively late in the systems as it is primarily observed along fractures in pyrite and gangue minerals. At Grand Duc gold appears to have formed syn- to post-crystallization relative to base metal sulphides (e.g. chalcopyrite, sphalerite, pyrrhotite), whereas base metal sulphides at Doyon are relatively rare. The accessory ore mineral assemblage at Doyon is relatively simple compared to Grand Duc, consisting of petzite (Ag3AuTe2), calaverite (AuTe2), and hessite (Ag2Te), while accessory ore minerals at Grand Duc are comprised of tellurobismuthite (Bi2Te3), volynskite (AgBiTe2), native Te, tsumoite (BiTe) or tetradymite (Bi2Te2S), altaite (PbTe), petzite, calaverite, and hessite. Pyrite trace element distribution maps from representative pyrite grains from Doyon and Grand Duc were collected and confirm petrographic observations that Au occurs relatively late. Pyrite from Doyon appears to have been initially trace-element poor, then became enriched in As, followed by the ore metal stage consisting of Au-Ag-Te-Bi-Pb-Cu enrichment and lastly a Co-Ni-Se(?) stage enrichment. Grand Duc pyrite is more complex with initial enrichments in Co-Se-As (Stage 1) followed by an increase in As-Co(?) concentrations (Stage 2). The ore metal stage (Stage 3) is indicated by another increase in As coupled with Au-Ag-Bi-Te-Sb-Pb-Ni-Cu-Zn-Sn-Cd-In enrichment. The final stage of pyrite growth (Stage 4) is represented by the same element assemblage as Stage 3 but at lower concentrations. Preliminary sulphur isotope data from Grand Duc indicates pyrite, pyrrhotite, and chalcopyrite all have similar delta-34S values (~1.5 � 1 permille) with no core-to-rim variations. Pyrite from Doyon has slightly higher delta-34S values (~2.5 � 1 permille) compared to Grand Duc but similarly does not show much core-to-rim variation. At Grand Duc, the occurrence of Au concentrating along the rim of pyrite grains and associated with an enrichment in As and other metals (Sb-Ag-Bi-Te) shares similarities with porphyry and epithermal deposits, and the overall metal association of Au with Te and Bi is a hallmark of other intrusion-related gold systems. The occurrence of the ore metal-rich rims on pyrite from Grand Duc could be related to fluid boiling which results in the destabilization of gold-bearing aqueous complexes. Pyrite from Doyon does not show this inferred boiling texture but shares characteristics of dissolution-reprecipitation processes, where metals in the pyrite lattice are dissolved and then reconcentrated into discrete mineral phases that commonly precipitate in voids and fractures created during pyrite dissolution.
5
Armistead, S. E., R. G. Skirrow, G. L. Fraser, D. L. Huston, D. C. Champion e M. D. Norman. Gold and intrusion-related Mo-W mineral systems in the southern Thomson Orogen, New South Wales. Geoscience Australia, 2017. http://dx.doi.org/10.11636/record.2017.005.
6
Rahmé, Marianne, e Alex Walsh. Corruption Challenges and Responses in the Democratic Republic of Congo. Institute of Development Studies, gennaio 2022. http://dx.doi.org/10.19088/k4d.2022.093.
Abstract (sommario):
The Democratic Republic of the Congo (DRC) consistently scores in the lowest rungs of global indexes on corruption, integrity and wider governance standards. Indeed, corruption of different sorts pervades public and corporate life, with strong ramifications for human development. Although the DRC is one of the richest countries in the world in terms of natural resources, its people are among the globe’s poorest.Corruption in the extractive industries (minerals and oil) is particularly problematic in terms of scale and its centrality to a political economy that maintains elites and preserves the highly inequitable outcomes for the majority. The politico-economic elites of the DRC, such as former President Joseph Kabila, are reportedly significant perpetrators but multinationals seeking valuable minerals or offering financial services are also allegedly deeply involved. Corruption is therefore a problem with national and international roots.Despite national and international initiatives, levels of corruption have proven very stubborn for at least the last 20 years, for various reasons. It is a structural and not just a legal issue. It is deeply entrenched in the country’s political economy and is driven both by domestic clientelism and the fact that multinationals buy into corrupt deals. This rapid review therefore seeks to find out the Corruption challenges and responses in the Democratic Republic of Congo.Grand level corruption shades down into the meso-level, where for instance, mineral laden trucks are systematically under-weighted with the collusion of state officials. With severe shortfalls in public funding, certain public services, such as education, are supported by informal payments. Other instances of petty corruption facilitate daily access to goods and services. At this level, there are arguments against counting such practices as forms of corruption and instead as necessary survival practices.To address the challenge of corruption, the DRC is equipped with a legal system that is of mixed strengths and an institutional arsenal that has made limited progress. International programming in integrity and anti-corruption represents a significant proportion of support to the DRC but much less than humanitarian and governance sectors. The leading international partners in this regard are the EU, US, UNDP, UK, African Development Bank, Germany and Sweden. These partners conduct integrity programming in general governance issues, as well as in the mineral and forest sectors.The sources used in this rapid review are gender blind and converge on a very negative picture The literature ranges from the academic and practitioner to the journalistic and investigative, and taken as a whole, is of good quality, drawing on different types of evidence including perceptions and qualitative in-country research. The sources are mostly in English with two in French.
7
Price, Roz. Taxation and Public Financial Management of Mining Revenue in the Democratic Republic of Congo. Institute of Development Studies (IDS), ottobre 2021. http://dx.doi.org/10.19088/k4d.2021.144.
Abstract (sommario):
This rapid review provides a summary of the evidence on the taxation and public financial management of mining revenues in the Democratic Republic of Congo (DRC). This is a very complex topic, with a large and growing literature base, a huge interest by donors, non-governmental organisations and businesses, with some conflicting information at times. In particular, specific data on provincial budgets and spending was not identified during this review. No specific information on public financial management in either of these provinces was identified during the course of this review. Given the burgeoning size of the literature base and the complexity of the mining sector in the DRC, this rapid review only provides a snapshot of the literature. It draws on academic, grey and donor literature sources. Some papers for further reading are highlighted. The report first provides a brief background discussion of general taxation in the DRC, the decentralisation process, and provincial public revenue management. The next section provides general information on the mining sector in the DRC, including the regulatory system and official duties, royalties and tax provisions. Section 4 goes into more detail about taxation and rent-seeking in the mining sector, touching on both large-scale mining (LSM) and artisanal and small-scale mining (ASM). The next section looks at smuggling of minerals in the DRC, with a focus on gold. Finally, some specific lessons learned were drawn from two World Bank projects and highlighted in the final section. Lessons and experiences from other mining-related projects are also highlighted throughout the report. Literature in French was not included in this rapid review, which may mean that some key documents were omitted.
8
Geochemistry, geochronology, mineralogy, and geology suggest sources of and controls on mineral systems in the southern Toquima Range, Nye County, Nevada; with geochemistry maps of gold, silver, mercury, arsenic, antimony, zinc, copper, lead, molybdenum, bismuth, iron, titanium, vanadium, cobalt, beryllium, boron, fluorine, and sulfur; and with a section on lead associations, mineralogy and paragenesis, and isotopes. US Geological Survey, 2003. http://dx.doi.org/10.3133/mf2327c.