To see the other types of publications on this topic, follow the link: Intermediate sulfidation epithermal deposits.
Journal articles on the topic 'Intermediate sulfidation epithermal deposits'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Intermediate sulfidation epithermal deposits.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Tămaș, Călin Gabriel, Mădălina Paula Andrii, Réka Kovács, Sergiu Drăgușanu, and Béatrice Cauuet. "Sphalerite Composition in Low- and Intermediate-Sulfidation Epithermal Ore Bodies from the Roșia Montană Au-Ag Ore Deposit, Apuseni Mountains, Romania." Minerals 11, no. 6 (June 15, 2021): 634. http://dx.doi.org/10.3390/min11060634.
Full textAbstract:
We evaluated the significance of the iron and manganese content in sphalerite as a tool for distinguishing between low-sulfidation and intermediate-sulfidation epithermal deposits on the basis of new and previously published electron probe microanalyses data on the Roșia Montană epithermal ore deposit and available microchemical data from the Neogene epithermal ore deposits located in the Apuseni Mountains and Baia Mare region, Romania. Two compositional trends of the Fe vs. Mn content in sphalerite were delineated, a Fe-dominant and a Mn-dominant, which are poor in Mn and Fe, respectively. The overlapping compositional range of Fe and Mn in sphalerite in low-sulfidation and intermediate-sulfidation ores suggests that these microchemical parameters are not a reliable tool for distinguishing these epithermal mineralization styles.
2
Baker, T. "Gold ± Copper Endowment and Deposit Diversity in the Western Tethyan Magmatic Belt, Southeast Europe: Implications for Exploration." Economic Geology 114, no. 7 (November 1, 2019): 1237–50. http://dx.doi.org/10.5382/econgeo.4643.
Full textAbstract:
Abstract Major Au and Cu deposits in the Western Tethyan magmatic belt formed during two main periods of Cretaceous and Cenozoic magmatism. The Cretaceous deposits are dominantly Cu-Au porphyry, high-sulfidation epithermal, and volcanic massive sulfide deposits, whereas in the Cenozoic Cu is significant only in porphyry systems. However, the Cenozoic contains approximately three times greater total Au endowment (for Au deposits >0.5 million ounces), and also has a greater deposit diversity, including porphyry Au-Cu and Au-only deposits, high-, intermediate-, and low-sulfidation epithermal Au systems, and Au-rich carbonate replacement and sediment-hosted styles. The differences in endowment and deposit styles likely reflect regional-scale tectono-magmatic processes as well as local preservation and emplacement levels. The Cu ± Au endowment of the Cretaceous is consistent with typical subduction-related arc environments and generation of calc-alkaline porphyry to high-sulfidation epithermal systems, whereas Au enrichment related to Cenozoic magmatism appears to be related to high-K calc-alkalic to shoshonitic compositions. In many of the Au-rich Cenozoic magmatic belts, there is geochemical evidence for sourcing subcontinental lithospheric mantle that was previously enriched by Cretaceous subduction-related metasomatism. Additional differences in Au endowment may reflect the preservation of shallow-level systems in the Cenozoic, particularly for the Au-rich Miocene porphyry deposits such as Kışladağ and Bierly Vrch and the Apuseni porphyry Au-Cu deposits. However, in both the Cretaceous and Cenozoic, crustal exposure levels vary across the belt and cannot explain all the differences in Cu and Au endowment. A compilation of exploration discovery methods highlights the importance of historic workings in addition to geochemistry and geology as an initial vector, whereas geophysics has had limited involvement in direct discovery, primarily due to its limited application historically. Geologic models for well-understood systems such as porphyry and proximal epithermal systems provide excellent guides for explorers; however, more distal deposits such as Au-rich carbonate replacement deposits and deposits with poorly constrained models such as sedimentary rock-hosted and intermediate-sulfidation deposits are more challenging for exploration.
3
Michael, C. "EPITHERMAL SYSTEMS AND GOLD MINERALIZATION IN WESTERN THRACE (NORTHERN GREECE)." Bulletin of the Geological Society of Greece 36, no. 1 (January 1, 2004): 416. http://dx.doi.org/10.12681/bgsg.16727.
Full textAbstract:
Extensive epithermal systems occur within the Tertiary volcanosedimentary basins of western Thrace northern Greece. Gold deposits or perspective gold districts, related to the above epithermal systems have been recently found in the area. The gold mineralization is of the high – sulfidation type and is associated to a diversity in composition and style volcanic activity. Sappes epithermal system is the most important (Saint Demetrios and Viper deposits) and has developed in volcanic "ocks of intermediate composition accompanied by subvolcanic intrusives (dacite - andésites) and plutonio rocks (quartz - monzodiorites). Saint Demetrios and Viper gold deposits are flat lying and of high sulfidation type mineralizations hosted in hydrothermal breccia zones. Petrota epithermal system has developed in volcanoclastic and epiclastic rocks (Perama Hill gold deposit), in rhyolites (location Othontoto) and within hyaloclastites and crystal tuffs (location Mavrokoryfi). The mineralized epithermal zones have strong structural control. Perama gold deposit occurs at the intersection of NS and NW trending epithermal zones. These structures represent the higher grade "feeder" system. Pefka epithermal system is hosted in more acid volcanic vocks (dacites, rhyodacites) and at its southern part (Pasa lofos area) the system is associated with a more alkaline suit (shoshonitic rocks). The mineralized silicifid zones at Pefka mine would correspond to concentric fractures (sheeted fracturing) parallel to the margin of the breccia pipe. The gold mineralization occurs in veins. In general gold occurs in the form of native gold, gold tellurides or it is associated with enargite, luzonite, tetrahedhte. Advanced argillic alteration and intense silicification are very important for the epithermal systems in western Thrace. A unique low - sulfidation occurrence was found at the central and southern part of Sappes area. Adularla was found in veinlets overlapping argillic alteration zones of high - sulfidation system.
4
Wang, Le, Ke-Zhang Qin, Guo-Xue Song, and Guang-Ming Li. "A review of intermediate sulfidation epithermal deposits and subclassification." Ore Geology Reviews 107 (April 2019): 434–56. http://dx.doi.org/10.1016/j.oregeorev.2019.02.023.
Full text
5
Juliani, Caetano, Rafael Rodrigues de Assis, Lena Virgínia Soares Monteiro, Carlos Marcello Dias Fernandes, José Eduardo Zimmermann da Silva Martins, and Jhoseph Ricardo Costa e Costa. "Gold in Paleoproterozoic (2.1 to 1.77 Ga) Continental Magmatic Arcs at the Tapajós and Juruena Mineral Provinces (Amazonian Craton, Brazil): A New Frontier for the Exploration of Epithermal–Porphyry and Related Deposits." Minerals 11, no. 7 (July 1, 2021): 714. http://dx.doi.org/10.3390/min11070714.
Full textAbstract:
This review paper aims to integrate geological, tectonic and metallogenetic data, including new data, and propose a regional model for the gold (and base metal) mineralization in the south Amazonian Craton to support the mineral exploration concerning magmatic–hydrothermal deposits. The Proterozoic evolution of the Amazonian Craton comprises the accretion of terrains to the Archean Carajás Mineral Province. In the Tapajós and Juruena mineral provinces, located at the south part of the Amazonian craton, a long-lived ocean–continent subduction event produced ca. 2.0 to 1.77 Ga continental magmatic arcs. Extensive lava flows, volcaniclastic, sedimentary, and plutonic rocks were originated during at least four major orogenic magmatic events (ca. 2.1, 1.9, 1.88, and 1.80 Ga) and two post- to anorogenic events (ca. 1.87 and 1.77 Ga). Gold mineralization occurs in: (i) alluvial/colluvial occurrences, (ii) orogenic carbonate–sulfide-rich quartz veins in shear zones, (iii) stockworks, veins, and dissemination in granites, (iv) contact of basic dikes, (v) well-preserved high-, intermediate- and low-sulfidation epithermal mineralization, and (vi) porphyry-like and intrusion-related gold systems associated with late- to post-orogenic epizonal granites. The estimated historical gold production, mainly in secondary deposits, is over 27 Moz at the Tapajós and 6 Moz at the Juruena provinces. A total resource of over 5 Moz Au is currently defined in several small to large primary gold deposits. Andesite to rhyolite, volcaniclastic, and clastic sedimentary rocks (1.96–1.88 Ga) host epithermal (high-, intermediate-, and low-sulfidation) Au–(Ag–Pb–Zn) mineralization, whereas Au–Cu and Cu–M–Au mineralization is hosted in sub-volcanic tonalitic to granitic plutons. Advanced argillic alteration (alunite, pyrophyllite, enargite) associated with high-sulfidation mineralization occurs in ring volcanoes around nested volcanic calderas. This zone grades outward to propylitic or chlorite alteration, often covered by silica caps with vuggy silica. Lava flows and volcaniclastic rocks within faults or associated with volcanic edifices and rhyolitic domes host low- and intermediate-sulfidation mineralization. Low-sulfidation alteration zones typically have adularia and illite or sericite. Chalcopyrite, sphalerite, galena, pyrite, digenite, and manganiferous calcite are related to intermediate-sulfidation gold mineralization. Late- to post-orogenic evolved oxidized I-type granitoids host alkalic-type epithermal and porphyry-like gold mineralization. Porphyry-style hydrothermal alteration is analogous to those of modern systems, with inner sodic and potassic (potassic feldspar ± biotite or biotite) alterations grading to propylitic, muscovite-sericite, chlorite–sericite, and chlorite alterations. Potassic alteration zones are the locus of Cu–Mo mineralization, and gold-rich zones occur in muscovite/sericite–quartz–pyrite alteration. The Paleoproterozoic epithermal and porphyry-like mineralization in these large provinces defines a new frontier for the exploration of world-class gold deposits in the worldwide Proterozoic arc-related magmatic terrains.
6
Bortnikov, N. S., A. V. Volkov, N. E. Savva, V. Yu Prokofiev, E. E. Kolova, A. A. Dolomanova-Topol’, A. L. Galyamov, and K. Yu Murashov. "Epithermal Au–Ag–Se–Te Deposits of the Chukchi Peninsula (Arctic Zone of Russia): Metallogeny, Mineral Assemblages, and Fluid Regime." Russian Geology and Geophysics 63, no. 4 (April 1, 2022): 435–57. http://dx.doi.org/10.2113/rgg20214425.
Full textAbstract:
Abstract Numerous epithermal Au–Ag deposits and ore occurrences of the Chukchi Peninsula are localized in the Cretaceous Okhotsk–Chukotka (OCVB) continent-marginal and Late Jurassic–Early Cretaceous Oloi (OVB) island arc volcanic belts and in Early Cretaceous postcollisional volcanic troughs. Volcanotectonic depressions, calderas, and volcanic domes control the location of the deposits. The orebodies of the deposits are quartz–adularia veins, sometimes en-echelon ones forming extending vein zones, as well as isometric and linear stockworks. The auriferous veins of most deposits display complex breccia–crustification structures. The vein ores have rhythmically and colloform–banded structures, with a predominantly fine distribution of ore mineral grains, often with banded clusters of ore minerals (ginguro). Native gold is of low fineness; the dispersion of this index varies from low to high. Acanthite is widespread in the ores. Its highest contents are specific to deposits with the repeated redistribution of substance (Kupol, Corrida, and Valunistoe). Based on the results of mineralogical studies, most of the epithermal Au–Ag deposits of the Chukchi Peninsula can be assigned to the Se type. The ores of some deposits (Valunistoe, Dvoinoe, etc.) contain both Se and Te minerals. The telluride-richest sites of the Sentyabr’skoe and Televeem deposits are far from the main orebodies. Most of the Chukchi epithermal Au–Ag deposits have many common characteristics (low and moderate temperatures of fluids, low fluid salinity, domination of carbon dioxide over methane, etc.) typical of low-sulfidation deposits. The maximum temperatures and salinity are specific to fluids in the Central Chukchi sector of the OCVB and in the Baimka zone of the OVB, and the minimum ones are typical of fluids in the East Chukchi flank zone and inner zone of the OCVB. The average salinity of mineral-forming fluids in the inner zone of the OCVB is half as high as the salinity of fluids in the East Chukchi flank zone of this belt, although the sulfate content is higher. At the same time, the fluids in the inner zone of the OCVB are richer in carbon dioxide and bicarbonate ion than the fluids in the East Chukchi flank zone of this belt. The fluid inclusion data permit the Vesennee deposit (Baimka zone) to be regarded as an intermediate-sulfidation one and suggest the presence of epithermal high-sulfidation deposits in the inner zone of the OCVB.
7
Sahlström, Fredrik, Antonio Arribas, Paul Dirks, Isaac Corral, and Zhaoshan Chang. "Mineralogical Distribution of Germanium, Gallium and Indium at the Mt Carlton High-Sulfidation Epithermal Deposit, NE Australia, and Comparison with Similar Deposits Worldwide." Minerals 7, no. 11 (November 5, 2017): 213. http://dx.doi.org/10.3390/min7110213.
Full textAbstract:
Germanium, gallium and indium are in high demand due to their growing usage in high-tech and green-tech applications. However, the mineralogy and the mechanisms of concentration of these critical elements in different types of hydrothermal ore deposits remain poorly constrained. We investigated the mineralogical distribution of Ge, Ga and In at the Mt Carlton high-sulfidation epithermal deposit in NE Australia, using electron probe microanalysis and laser ablation inductively-coupled plasma mass spectrometry. Parageneses from which selected minerals were analyzed include: Stage 1 acid sulfate alteration (alunite), Stage 2A high-sulfidation enargite mineralization (enargite, argyrodite, sphalerite, pyrite, barite), Stage 2B intermediate-sulfidation sphalerite mineralization (sphalerite, pyrite, galena) and Stage 3 hydrothermal void fill (dickite). Moderate to locally high concentrations of Ga were measured in Stage 1 alunite (up to 339 ppm) and in Stage 3 dickite (up to 150 ppm). The Stage 2A ores show enrichment in Ge, which is primarily associated with argyrodite (up to 6.95 wt % Ge) and Ge-bearing enargite (up to 2189 ppm Ge). Co-existing sphalerite has comparatively low Ge content (up to 143 ppm), while Ga (up to 1181 ppm) and In (up to 571 ppm) are higher. Sphalerite in Stage 2B contains up to 611 ppm Ge, 2829 ppm Ga and 2169 ppm In, and locally exhibits fine colloform bands of an uncharacterized Zn-In mineral with compositions close to CuZn2(In,Ga)S4. Barite, pyrite and galena which occur in association with Stage 2 mineralization were found to play negligible roles as carriers of Ge, Ga and In at Mt Carlton. Analyzed reference samples of enargite from seven similar deposits worldwide have average Ge concentrations ranging from 12 to 717 ppm (maximum 2679 ppm). The deposits from which samples showed high enrichment in critical elements in this study are all hosted in stratigraphic sequences that locally contain carbonaceous sedimentary rocks. In addition to magmatic-hydrothermal processes, such rocks could potentially be important for the concentration of critical elements in high-sulfidation epithermal deposits.
8
Purwanto, Heru Sigit, and Sari Bahagiarti Kusumayudha. "Type of Gold Deposit in Arinem Cisewu and Its Surrounding Garut Regency, West Java, Indonesia." International Journal of Geology and Earth Sciences 6, no. 4 (December 2020): 39–43. http://dx.doi.org/10.18178/ijges.6.4.39-43.
Full textAbstract:
Gold deposit based on the mineralization of gold and other ore minerals in Arinem area and its surrounding was found in the quartz vein. The research area is in Arinem area and its surrounding, Garut Regency, West Java. Arinem and the vicinity was the location for early stage of research program of mineralization in Papandayan area. This area has good mineralization, and according to previous studies, is a low sulfidation area with the presence of pyrite, chalcopyrite, galena and sphalerite (Antam, 2014). The presence of galena and sphalerite mineral has suggested that instead of low sulfidation, the area may be in intermediate sulfidation zone state supported by other data such as quartz breccia, banded quartz and shear as control structure. Lithology in the area consists of breccia Quaternary and lava unit of Jampang formation in Miocene and unit of andesite and basaltic in Quaternary and intrusion of dacite, andesite and diorite. The alteration and mineralization of research area was classified as propylitic alteration zone with the presence of chlorite, epidote and calcite mineral, argillic alteration zone with montmorillonite, kaolinite mineral, silicic alteration zone with the presence of quartz-sericite, a bit of calcite mineral. The observed ore minerals are pyrite, chalcopyrite, galena, sphalerite. The geological structure was controlled by horizontal fault in almost north-south direction of N 170O-180O E and northeast – southwest horizontal fault in N 40O – 50O E, while the mineralization zone was controlled or following fault pattern of N 170O - 175O E. The epithermal deposit of the study area can be classified as intermediate sulfidation epithermal deposit for zones with galena and sphalerite mineral particularly on several locations near fault zones and brecciated quartz. Meanwhile, the study area is generally low sulfidation epithermal type deposit.
9
Baker, Michael J., Jamie J. Wilkinson, Clara C. Wilkinson, David R. Cooke, and Tim Ireland. "Epidote Trace Element Chemistry as an Exploration Tool in the Collahuasi District, Northern Chile." Economic Geology 115, no. 4 (June 1, 2020): 749–70. http://dx.doi.org/10.5382/econgeo.4739.
Full textAbstract:
Abstract The Collahuasi district of northern Chile hosts several late Eocene-early Oligocene world-class porphyry Cu-Mo deposits, including Rosario, Ujina, and Quebrada Blanca deposits, and associated high-sulfidation epithermal mineralization at La Grande. Mineralization is hosted by intermediate to felsic intrusive and volcanic rocks of the upper Paleozoic to Lower Triassic Collahuasi Group, which experienced lower greenschist facies regional metamorphism prior to mineralization. Extensive hydrothermal alteration zones surround the porphyry and epithermal deposits, associated with hypogene ore-forming processes. However, outside of the observed sulfide halo the limits of geochemical anomalism associated with mineralization are difficult to define due to mineralogical similarities between weak, distal propylitic alteration and regional metamorphism affecting the host rocks. Recent advancements in laser ablation-inductively coupled plasma-mass spectrometry analysis of epidote from hydrothermal alteration zones around porphyry and skarn deposits have shown that low-level hypogene geochemical anomalies can be detected at distances farther from the center of mineralization than by conventional rock chip sampling. Selective analysis of propylitic epidote from the Collahuasi district indicates that anomalous concentrations of distal pathfinder elements in epidote, including As (>50 ppm), Sb (>25 ppm), Pb (>100 ppm), and Mn (>5,000 ppm), were detectable 1.5 to 4.0 km from deposit centers. Significantly, the concentrations of these trace elements in epidote were obtained from samples that contained whole-rock concentrations of <25 ppm As, <2 ppm Sb, <100 ppm Pb, and <5,000 ppm Mn. Systematic increases in Cu, Mo, and Sn concentrations in epidote near deposit centers, and corresponding decreasing As, Sb and Pb concentrations, also provide effective tools for assessing the fertility and locating the centers of porphyry mineralization. In addition, anomalous concentrations in epidote of Cu (up to 1 wt %) and Zn (up to 6,000 ppm) effectively discriminate epidote associated with high-sulfidation epithermal veins in the Collahuasi district (e.g., La Grande, Poderosa-Rosario) from alteration associated with porphyry mineralization.
10
Tuduri, Johann, Alain Chauvet, Luc Barbanson, Jean-Louis Bourdier, Mohamed Labriki, Aomar Ennaciri, Lakhlifi Badra, et al. "The Jbel Saghro Au(–Ag, Cu) and Ag–Hg Metallogenetic Province: Product of a Long-Lived Ediacaran Tectono-Magmatic Evolution in the Moroccan Anti-Atlas." Minerals 8, no. 12 (December 13, 2018): 592. http://dx.doi.org/10.3390/min8120592.
Full textAbstract:
The Jbel Saghro is interpreted as part of a long-lived silicic large igneous province. The area comprises two lithostructural complexes. The Lower Complex consists of folded metagreywackes and N070–090°E dextral shear zones, which roughly results from a NW–SE to NNW–SSE shortening direction related to a D1 transpressive tectonic stage. D1 is also combined with syntectonic plutons emplaced between ca. 615 and 575 Ma. The Upper Complex is defined by ash-flow caldera emplacements, thick and widespread ignimbrites, lavas and volcaniclastic sedimentary rocks with related intrusives that were emplaced in three main magmatic flare ups at ca. 575, 565 and 555 Ma. It lies unconformably on the Lower Complex units and was affected by a D2 trantensive tectonic stage. Between 550 and 540 Ma, the magmatic activity became slightly alkaline and of lower extent. Ore deposits show specific features, but remain controlled by the same structural setting: a NNW–SSE shortening direction related to both D1 and D2 stages. Porphyry Au(–Cu–Mo) and intrusion-related gold deposits were emplaced in an earlier stage between 580 and 565 Ma. Intermediate sulfidation epithermal deposits may have been emplaced during lull periods after the second and (or) the third flare-ups (560–550 Ma). Low sulfidation epithermal deposits were emplaced late during the felsic alkaline magmatic stage (550–520 Ma). The D2 stage, therefore, provided extensional structures that enabled fluid circulations and magmatic-hydrothermal ore forming processes.
11
Sahlström, Fredrik, Zhaoshan Chang, Antonio Arribas, Paul Dirks, Craig A. Johnson, Jan Marten Huizenga, and Isaac Corral. "Reconstruction of an Early Permian, Sublacustrine Magmatic-Hydrothermal System: Mount Carlton Epithermal Au-Ag-Cu Deposit, Northeastern Australia." Economic Geology 115, no. 1 (January 1, 2020): 129–52. http://dx.doi.org/10.5382/econgeo.4696.
Full textAbstract:
Abstract The Mt. Carlton Au-Ag-Cu deposit, northern Bowen basin, northeastern Australia, is an uncommon example of a sublacustrine hydrothermal system containing economic high-sulfidation epithermal mineralization. The deposit formed in the early Permian and comprises vein- and hydrothermal breccia-hosted Au-Cu mineralization within a massive rhyodacite porphyry (V2 open pit) and stratabound Ag-barite mineralization within volcano-lacustrine sedimentary rocks (A39 open pit). These orebodies are all associated with extensive advanced argillic alteration of the volcanic host rocks. Stable isotope data for disseminated alunite (δ34S = 6.3–29.2‰; δ18OSO4 = –0.1 to 9.8‰; δ18OOH = –15.3 to –3.4‰; δD = –102 to –79‰) and pyrite (δ34S = –8.8 to –2.7‰), and void-filling anhydrite (δ34S = 17.2–19.2‰; δ18OSO4 = 1.8–5.7‰), suggest that early advanced argillic alteration formed within a magmatic-hydrothermal system. The ascending magmatic vapor (δ34SΣS ≈ –1.3‰) was absorbed by meteoric water (~50–60% meteoric component), producing an acidic (pH ≈ 1) condensate that formed a silicic → quartz-alunite → quartz-dickite-kaolinite zoned alteration halo with increasing distance from feeder structures. The oxygen and hydrogen isotope compositions of alunite-forming fluids at Mt. Carlton are lighter than those documented at similar deposits elsewhere, probably due to the high paleolatitude (~S60°) of northeastern Australia in the early Permian. Veins of coarse-grained, banded plumose alunite (δ34S = 0.4– 7.0‰; δ18OSO4 = 2.3–6.0‰; δ18OOH = –10.3 to –2.9‰; δD = –106 to –93‰) formed within feeder structures during the final stages of advanced argillic alteration. Epithermal mineralization was deposited subsequently, initially as fracture- and fissure-filling, Au-Cu–rich assemblages within feeder structures at depth. As the mineralizing fluids discharged into lakes, they produced syngenetic Ag-barite ore. Isotope data for ore-related sulfides and sulfosalts (δ34S = –15.0 to –3.0‰) and barite (δ34S = 22.3–23.8‰; δ18OSO4 = –0.2 to 1.3‰), and microthermometric data for primary fluid inclusions in barite (Th = 116°– 233°C; 0.0–1.7 wt % NaCl), are consistent with metal deposition at temperatures of ~200 ± 40°C (for Au-Cu mineralization in V2 pit) and ~150 ± 30°C (Ag mineralization in A39 pit) from a low-salinity, sulfur- and metal-rich magmatic-hydrothermal liquid that mixed with vapor-heated meteoric water. The mineralizing fluids initially had a high-sulfidation state, producing enargite-dominated ore with associated silicification of the early-altered wall rock. With time, the fluids evolved to an intermediate-sulfidation state, depositing sphalerite- and tennantite-dominated ore mineral assemblages. Void-filling massive dickite (δ18O = –1.1 to 2.1‰; δD = –121 to –103‰) with pyrite was deposited from an increasingly diluted magmatic-hydrothermal liquid (≥70% meteoric component) exsolved from a progressively degassed magma. Gypsum (δ34S = 11.4–19.2‰; δ18OSO4 = 0.5–3.4‰) occurs in veins within postmineralization faults and fracture networks, likely derived from early anhydrite that was dissolved by circulating meteoric water during extensional deformation. This process may explain the apparent scarcity of hypogene anhydrite in lithocaps elsewhere. While the Mt. Carlton system is similar to those that form subaerial high-sulfidation epithermal deposits, it also shares several key characteristics with magmatic-hydrothermal systems that form base and precious metal mineralization in shallow-submarine volcanic arc and back-arc settings. The lacustrine paleosurface features documented at Mt. Carlton may be useful as exploration indicators for concealed epithermal mineralization in similar extensional terranes elsewhere.
12
Myaing, Yu Yu, Arifudin Idrus, and Anastasia Dewi Titisari. "Fluid Inclusion Study of The Tumpangpitu High Sulfidation Epithermal Gold Deposit in Banyuwangi District, East Java, Indonesia." Journal of Geoscience, Engineering, Environment, and Technology 3, no. 1 (March 1, 2018): 8. http://dx.doi.org/10.24273/jgeet.2018.3.01.1039.
Full textAbstract:
The Tumpangpitu high sulfidation (HS) epithermal gold deposit is located in the south coast of East Java, Banyuwangi District, East Java Province, Indonesia. This area lies within the central portion of the Cenozoic Sunda‐Banda magmatic arc which trends southeast from northern Sumatra to west Java then eastward through east Java, Bali, Lombok, Sumbawa and terminating at Banda sea. The geology of the Tumpangpitu is predominantly occupied by Late Oligocene to Middle Miocene low-K calc-alkaline to alkaline andesitic volcanic rocks and interbedded with volcaniclastic rock sequences, which are associated with low-K intermediate intrusions. The mineralization style at the Tumpangpitu area is composed of a high‐sulfidation (HS) epithermal gold-copper system which is typically associated with concealed gold-rich porphyry copper system. The HS epithermal mineralization is hosted by volcanic and volcaniclastic rocks in this research area. The mineralization domains are divided into Zone A, Zone B and Zone C which are situated along NW-SE-trending silica ledges zones. The HS epithermal mineralization is texturally occurs as vuggy replacements mineralization as well as stockworks, disseminated forms, fractures and veins. Fluid inclusion study was conducted for 6 quartz vein samples which petrographically entrapped fluid inclusions. Homogenization temperature (Th) and melting temperature (Tm) can microthermometrically be determined by fluid inclusion analysis. The average homogenization temperature (Th) of the fluid inclusions gives 180˚C to 342˚C and melting temperature are from -0.1 ˚C to -1.4˚C. Tm corresponds to the salinities ranging from 0.1 to 4.5 wt% NaCl equivalent. The paleodepth of ore formation can be estimated from the salinity of fluid. Since the deposit was not formed at boiling condition, the minimum paleodepth of ore (quartz) samples taken from both shallow level (53.35 m) and deep level (135.15 m) is determined at 650m and 1,220 m, respectively. The microthermometric data point out that the Tumpangpitu deposit formed at moderate temperature and low salinity by magmatic fluid mixing and dilution by meteoric water during the hydrothermal fluid evolution. On the basis of the fluid inclusion microthermometric data and its other key characteristics, the Tumpangpitu gold mineralization shares some similarities compared to other typical HS-epithermal gold deposits worlwide although it also shares few differences.
13
Olivo, G. R., and K. Gibbs. "Paragenesis and mineral chemistry of alabandite (MnS) from the Ag-rich Santo Toribio epithermal deposit, Northern Peru." Mineralogical Magazine 67, no. 1 (February 2003): 95–102. http://dx.doi.org/10.1180/0026461036710087.
Full textAbstract:
AbstractThe Miocene, epithermal, Ag-rich polymetallic Santo Toribio deposit is hosted by the volcanics of the Quiruvilva-Pierina subbelt, Northern Peru, which also comprises the world-class, high sulphidation Pierina deposit. The Ag-rich, alabandite-bearing veins of the Santo Toribio deposit formed during two major stages. The early stage is characterized by deposition of arsenopyrite, pyrite, quartz, Mn- sphalerite, stannite, alabandite and minor miargyrite. Sphalerite associated with this stage is exceptionally enriched in Mn (up to 14.5 wt.%) and alabandite is optically and mineralogically zoned. Its brown zones have greater Fe+Sb and smaller Mn contents than the green zones and Fe+Sb replaces Mn in its structure. During this early stage, fs2 must have been high to allow the stabilization of alabandite relative to rhodochrosite. In the second stage, the physicochemical conditions changed and the CO2/S ratio increased, causing dissolution of alabandite and the deposition of abundant rhodochrosite and a second generation of arsenopyrite, pyrite and quartz, sphalerite with chalcopyrite inclusions, mirargyrite, ramdohrite, and finally stibnite. This polymetallic ore probably formed due to an abrupt decrease in H+ and/or Cl- concentration caused by boiling or dilution of the high-salinity hydrothermal fluids and constitutes an example of “intermediate sulfidation-state” epithermal deposits.
14
Fuentes-Guzmán, Edith, Antoni Camprubí, Janet Gabites, Eduardo González-Partida, and Vanessa Colás. "The Pliocene Xoconostle high sulfidation epithermal deposit in the Trans-Mexican Volcanic Belt: Preliminary study." Boletín de la Sociedad Geológica Mexicana 72, no. 3 (November 28, 2020): A260520. http://dx.doi.org/10.18268/bsgm2020v72n3a260520.
Full textAbstract:
The Xoconostle prospect in northeastern Michoacán state, south-central Mexico, is constituted by high sulfidation epithermal breccias and stockworks with Au and Hg prospective anomalies. The mineralization is hosted by latest Miocene to Pliocene rocks grouped into the El Terrero ignimbrite and the Siete Cruces dome complex and a stock of intermediate composition and undetermined (Pliocene?) age. Two alunite samples from deep hypogene advanced argillic alteration assemblages within the deposit yielded 40Ar/39Ar ages at 5.57 ± 0.44 (Messinian) and 3.67 ± 0.20 Ma (Zanclean). Such ages are in good agreement with those of volcanic rocks at a semi-regional scale, especially those associated with the nearby Amealco caldera. Assuming that the formation of Xoconostle deposit could be genetically related to any of the eruptive units in this caldera, it would be associated with dacitic-andesitic rocks at ~4.7 Ma or with bimodal andesite-basalt volcanism at ~3.7 Ma, with which rhyolites at the southwest rim of the caldera (nearer to the epithermal deposit) are contemporaneous. The obtained ages are also in good agreement with those determined for the youngest stages in the evolution of the Trans-Mexican Volcanic Belt (TMVB). In addition, such ages compare well with those established for the E-W striking Morelia-Acambay normal fault zone (or Acambay graben). The occurrence of E-W structural features in the study area support their correlation with those in the Acambay graben. Although the metallogenesis of the TMVB needs further endeavours that contribute to its understanding, the Xoconostle prospect adds up to other dated magmatic-hydrothermal deposits that may collectively constitute a Pliocene metallogenic province whose inception was geologically circumscribed to this volcanic arc. However, this and its companion papers in this issue confirm the metallogenic potential of the TMVB in most of its stages of evolution, particularly in the late Miocene-Pliocene stage of acid and bimodal volcanism.
15
Yilmaz, Huseyin, Tolga Oyman, F. Nuran Sonmez, Greg B. Arehart, and Zeki Billor. "Intermediate sulfidation epithermal gold-base metal deposits in Tertiary subaerial volcanic rocks, Sahinli/Tespih Dere (Lapseki/Western Turkey)." Ore Geology Reviews 37, no. 3-4 (June 2010): 236–58. http://dx.doi.org/10.1016/j.oregeorev.2010.04.001.
Full text
16
Abbassi, Bahman, Li Zhen Cheng, Jeremy P. Richards, Juliane Hübert, Jean M. Legault, Mark Rebagliati, and Ken Witherly. "Geophysical properties of an epithermal Au-Ag deposit in British Columbia, Canada." Interpretation 6, no. 4 (November 1, 2018): T907—T918. http://dx.doi.org/10.1190/int-2017-0232.1.
Full textAbstract:
The Newton Au-Ag deposit is an intermediate sulfidation state epithermal system in British Columbia, Canada. Multiple types of geophysical data are interpreted and evaluated with drillcore petrophysical, geochemical, and geologic observations to better understand the geophysical signature of the Newton epithermal system. Airborne [Formula: see text]-ray data sets indicate elevated emission counts of K, eTh, and eU over the Newton epithermal system, which are caused by hydrothermal alteration. Drillcore [Formula: see text]-ray measurements also indicate high potassium concentrations related to the K-rich phyllosilicates in the form of argillic and quartz-sericite alteration assemblages. Magnetization vector inversion (MVI) is used to recover an unconstrained 3D magnetization vector model of the system on regional and deposit scales. The regional MVI has resolved a deep concentric-shaped low magnetic zone that is interpreted as a porphyry system beneath the epithermal deposit. At the deposit scale, 3D direct current (DC) resistivity and induced polarization (IP) inversion, and unconstrained MVI revealed finer details of the epithermal system architecture. Cooperative DC/IP and magnetic inversion, at the deposit scale, constrained the magnetic susceptibility model and recovered a more precise susceptibility image of the epithermal system that is well-matched with borehole geology. The integrated geophysical interpretation helped to resolve several 3D latent geologic features in places without direct access to drillcore samples. We identified four petrophysical domains based on the three cooperatively inverted physical properties, including electrical resistivity, IP chargeability, and magnetic susceptibility. The combined geophysical models differentiated porphyritic intrusions (chargeability/susceptibility lows), disseminated sulfides (resistivity lows and chargeability highs), a Cu-rich zone in mafic volcanic rocks (susceptibility/chargeability highs and resistivity lows), and an Au-Ag-Cu-rich zone with silicification in felsic volcanic rocks (chargeability/susceptibility lows and resistivity highs). These petrophysical domains also provide useful exploration vectors for identification of similar epithermal systems.
17
Papavasiliou, K., P. Voudouris, C. Kanellopoulos, D. Alfieris, and S. Xydous. "THE KONDAROS-KATSIMOUTI INTERMEDIATESULFIDATION EPITHERMAL PB-ZN-AG-MN MINERALIZATION, WESTERN MILOS, GREECE: NEW MINERALOGICAL AND GEOCHEMICAL DATA." Bulletin of the Geological Society of Greece 50, no. 4 (July 28, 2017): 1959. http://dx.doi.org/10.12681/bgsg.14246.
Full textAbstract:
The metallic mineralization in Kontaros-Katsimouti area is an epithermal Pb-Zn Ag mineralization located along the NW-trending Kondaros-Katsimouti-Vani fault, NW Milos Island, Greece. It is hosted within propylitically and argillically altered dacitic flow dome and volcaniclastic sandstone and shows features typical of intermediate sulfidation deposits like colloform banding, cockade breccias and gangue adularia, Mnrich carbonates and amethystine quartz. The Kondaros-Katsimouti system evolves at higher elevation into the Vani Ag-Pb mineralization, which occurs proximal to the Vani manganese deposit. The metallic mineralogical assemblage at Kondaros-Katsimouti includes mainly galena and sphalerite and minor pyrite. Silver is present in the form of Ag-(Cd) rich tetrahedrite (up to 23.1 wt. % Ag) and polybasite included in galena. Bulk ore analyses indicate enrichment in W (up to 424 mg/kg) and Mo (up to 24 mg/kg), similarly to the other neighboring mineralizations in western Milos (e.g. Vani, TriadesGalana). This enrichment suggests a magmatic-hydrothermal contribution to the ore fluids, probably from a buried granitoid at depth. Boiling, in addition to mixing processes between magmatic- and seawater, resulted in pH increase, oxidation and temperature decrease, and resulted into ore deposition.
18
DRĂGUŞANU, Sergiu, Călin TĂMAŞ, and Béatrice CAUUET. "NEW GEOLOGICAL DATA ON ORLEA MINING FIELD, ROŞIA MONTANĂ AU-AG EPITHERMAL DEPOSIT, APUSENI MOUNTAINS, ROMANIA." Carpathian Journal of Earth and Environmental Sciences 17, no. 1 (February 2022): 159–70. http://dx.doi.org/10.26471/cjees/2022/017/210.
Full textAbstract:
New geological data on the Orlea mining field, Roșia Montană ore deposit, Romania were obtained by fieldwork carried out in the underground level +730 m, where three types of mineralized structures hosted by the Vent Breccia formation were studied, i.e., (i) flatly dipping vein with rhodochrosite gangue, (ii) steeply dipping tectonic breccia dyke, and (iii) steeply dipping base metal vein, respectively. The Vent Breccia is a polymictic matrix-supported breccia with sedimentary (clay, sandstone), volcanic (dacite), and metamorphic (quartzite, garnet micaschist) clasts. Four types of hydrothermal alterations were identified, i.e., (i) K-metasomatosis (adularia I); (ii) phyllic alteration (sericite); (iii) silicification; and (iv) potassic alteration (adularia II). The ore mineral assemblage consists of electrum, pyrite, chalcopyrite, sphalerite, galena, and minor arsenopyrite and pyrrhotite. The higher-grade ore body is the intermediate-sulfidation flatly dipping vein with rhodochrosite gangue grading up to 101g/t Au. The tectonic breccia dyke is a low-sulfidation ore body illustrating the evolution from early banded vein structure to late/final open-space clast supported tectonic breccia dyke.
19
Fan, Ming-Sen, Pei Ni, Jun-Yi Pan, Wen-Qing Huang, Su-Ning Li, Jun-Ying Ding, Wen-Sheng Li, Ren-Zhi Zhu, and Tan Bao. "The Maluntou Au deposit: A transitional mineralization type between low- and intermediate-sulfidation epithermal styles." Journal of Geochemical Exploration 242 (November 2022): 107087. http://dx.doi.org/10.1016/j.gexplo.2022.107087.
Full text
20
Wang, Le, Kezhang Qin, Guoxue Song, Xuyong Pang, Guangming Li, and Xinyu Zou. "Geology and genesis of the Early Paleozoic Zhengguang intermediate-sulfidation epithermal Au-Zn deposit, northeast China." Ore Geology Reviews 124 (September 2020): 103602. http://dx.doi.org/10.1016/j.oregeorev.2020.103602.
Full text
21
Mehrabi, Behzad, and Majid Ghasemi Siani. "Intermediate sulfidation epithermal Pb-Zn-Cu (±Ag-Au) mineralization at Cheshmeh Hafez deposit, Semnan province, Iran." Journal of the Geological Society of India 80, no. 4 (October 2012): 563–78. http://dx.doi.org/10.1007/s12594-012-0177-x.
Full text
22
Yusupova, A. V., I. A. Baksheev, and N. N. Koshlyakova. "Hydrothermal alteration and mineralization of the prospects at the northern flank of the Baimka ore zone, Western Chukotka." Proceedings of higher educational establishments. Geology and Exploration 63, no. 4 (October 12, 2021): 62–72. http://dx.doi.org/10.32454/0016-7762-2020-63-4-62-72.
Full textAbstract:
Background. Some papers describing the deposits and prospects in the Baimka ore zone (Baimka Trend), the Chukotka Autonomous Region have been recently published. It should be noted that those publications concern with the large Peschanka porphyry copper-molybdenum-gold deposit and Nakhodka ore field. At the same time, some copper prospects were found at the zone flanks and their nature is not clear. There are no data available in the literature that would clarify the mineralogy of hydrothermal alteration and ores at those prospects, including Top and Luchik located at the northern flank. To understand the nature of these prospects, we studied in depth mineralogy of hydrothermal alteration and ores.Aim. This study aims to describe mineralogy of metasomatic rocks and ores from the Top and Luchik prospects in the northern part of the Baimka zone, Western Chukotka.Materials and methods. Several dozen polished thin sections were microscopic studied at the Department of Mineralogy of Moscow State University using an optical microscope. The chemical composition of minerals was determined using electron microprobe at the Laboratory of Analytical Techniques of High Spatial Resolution, Department of Petrology and Volcanology, Moscow State University.Results. It was found that propylitic is the major hydrothermal alteration at the prospects studied here. Metasomatic rocks are cut by mineralized quartz and carbonate-quartz veins. Chalcopyrite and pyrite are the major ore minerals; galena, sphalerite, pyrite enriched in As and Sb, and marcasite are minor; Hg-bearing tetrahedrite-(Zn), native gold with the fineness of ~830, petzite, hessite, and acanthite are rare.Conclusions. The data obtained suggest that mineralization at the Top and Luchik prospect is attributed to the epithermal intermediate sulfidation type. Considering the occurrence of the epithermal mineralization in the upper part of the hydrothermal column and the porphyry mineralization in the Baimka zone, the porphyry mineralization is possible at depth at the Top and Luchik prospects.
23
Souza, Hugo Paiva Tavares de, Carlos Marcello Dias Fernandes, Ricardo de Freitas Lopes, Stéphane Amireault, and Marcelo Lacerda Vasquez. "Mineralizing Events of the World-Class Volta Grande Gold Deposit, Southeastern Amazonian Craton, Brazil." Environmental Sciences Proceedings 6, no. 1 (April 1, 2021): 19. http://dx.doi.org/10.3390/iecms2021-09537.
Full textAbstract:
The southeastern region of the Amazonian Craton has been the target of several metallogenetic surveys, which recently led to the identification of the world-class Volta Grande gold deposit with gold reserves of ~3.8 Moz at 1.02 g/t. This deposit is located ~60 km southeast of Altamira city, Pará state, and is hosted by the Três Palmeiras intrusive greenstone belt that is located in the northern Bacajá tectonic domain (2.24–2.0 Ga). The mineralization is hosted by a high-level intrusive and mylonitized suite. Local kinematic indicators suggest dip-slip movement in which the greenstone moves up relative to the intrusive rocks. Native gold mostly occurs as isolated grains in centimeter-wide quartz veins and veinlets associated with pervasive carbonate alteration that was synchronous with dynamic metamorphism. Part of the gold is also associated with disseminated sulfides in this generally low-sulfide mineralization. These relationships are compatible with orogenic lode-type gold systems elsewhere. New petrographic studies from core samples along a stratigraphic profile reveal the presence of lava flows and dykes of rhyodacite, rhyolite, and plutonic rocks such as quartz monzonite, granodiorite, monzodiorite, and subordinate microgranite crosscutting an earlier style of mineralization. These rocks are characterized by potassic, propylitic, intermediate argillic, and/or carbonate hydrothermal alterations in selective, pervasive, or fracture-controlled styles. Within the hydrothermal volcano-plutonic sequence, gold occurs as disseminated isolated grains or replacing sulfides. Both native gold and sulfides are also present in centimetric quartz veinlets. Such features of the deposit are similar to those from porphyry-type and low- to intermediate-sulfidation epithermal systems already identified in the Amazonian Craton. The Volta Grande deposit data suggest a second mineralizing event, common in large-tonnage gold deposits, and can represent a new exploration guide.
24
Mikaeili, Khadijeh, Mohammad Hosseinzadeh, Mohsen Moayyed, and Sajjad Maghfouri. "The Shah-Ali-Beiglou Zn-Pb-Cu (-Ag) Deposit, Iran: An Example of Intermediate Sulfidation Epithermal Type Mineralization." Minerals 8, no. 4 (April 10, 2018): 148. http://dx.doi.org/10.3390/min8040148.
Full text
25
Voudouris, P., I. Psimis, C. Mavrogonatos, C. Kanellopoulos, M. Kati, and E. Chlekou. "Amethyst occurrences in Tertiary volcanic rocks of Greece: mineralogical and genetic implications." Bulletin of the Geological Society of Greece 47, no. 1 (September 5, 2013): 477. http://dx.doi.org/10.12681/bgsg.11026.
Full textAbstract:
Epithermal-altered volcanic rocks in Greece host gem-quality amethyst veins in association with various silicates, carbonates, oxides, sulfides and halides. Host rocks are Oligocene to recent calc-alkaline to shoshonitic lavas and pyroclastics of intermediate- to acid composition. The amethyst-bearing veins occur in the periphery of porphyry-type and/or high-sulfidation epithermal mineralized centers in northern Greece (e.g. Sapes, Kirki, Kornofolia/Soufli, Lesvos island) and on Milos island in the active Aegean Volcanic Arc. Hydrothermal alteration around the quartz veins includes sericitic, K-feldspar (adularia), argillic, propylitic and zeolitic types. Precipitation of amethyst in the northern Greece occurrences, took place during the final stages of the magmatic-hydrothermal activity from near-neutral to alkaline fluids, as indicated by the presence of gangue adularia, calcite, smectite, chlorite, sericite, pyrite, zeolites (laumontite, heulandite, clinoptilolite), analcime and minor amounts of barite, halite, epidote and fluorite in the quartz veins. Amethyst at Milos Island (Chondro Vouno and Kalogries-Vani areas), is accompanied by barite, smectite and lepidocrocite. Colloform-crustiform banding with alternations of amethyst, chalcedony and/or carbonates is a common characteristic of the studied amethyst-bearing veins. Fluid inclusion- and mineralogical data suggest that the studied amethyst were formed at: 174-246 °C (Sapes area), 100-175 °C (Kirki and Kornofolia areas) and 223-234°C (Lesvos island). The amethyst formation requires oxidizing conditions and is probably the result of mixing between meteoric or seawater with upwelling hydrothermal fluids. The involvement of seawater in the studied mineralization is supported by the presence of halite and abundant barite in the veins. Finally, the studied amethyst deposits should be evaluated as potential gemstone sources in Greece.
26
Galanopoulos, Evangelos, Panagiotis Voudouris, Constantinos Mavrogonatos, Paul Spry, Craig Hart, Vasilios Melfos, Federica Zaccarini, and Dimitrios Alfieris. "A New Porphyry Mo Mineralization at Aisymi-Leptokarya, South-Eastern Rhodope, North-East Greece: Geological and Mineralogical Constraints." Geosciences 8, no. 12 (November 24, 2018): 435. http://dx.doi.org/10.3390/geosciences8120435.
Full textAbstract:
A new porphyry Mo prospect has been discovered in the Aisymi-Leptokarya area, along the southern margin of the Byala Reka–Kechros metamorphic dome, south-eastern (SE) Rhodope metallogenic zone. The study area is dominated by an Oligocene felsic dike complex, which hosts the porphyry Mo mineralization and intrudes into upper Eocene sandstones-marls and the Leptokarya monzodiorite pluton. The Aisymi-Leptokarya felsic dike complex displays a rhyodacitic to dacitic composition with post-collisional affinities. The porphyry Mo mineralization occurs in the form of porphyry-style quartz stockworks in the felsic dike complex associated with potassic alteration characterized by hydrothermal K-feldspar. The ore minerals consist mainly of pyrite, molybdenite, kesterite, bismuthinite and galena within both the stockwork and the rock matrix. Bulk ore analyses indicate enrichment in Mo (up to 215 ppm), Se (up to 29 ppm), Bi (up to 8 ppm) and Sn (up to 14 ppm) in the porphyry quartz veins. Late-stage, north-east (NE-) and north-west (NW-)trending milky quartz intermediate-sulfidation epithermal veins with base metals, crosscut previous vein generations and are characterized by Ag, Sn and Te anomalies. The Aisymi-Leptokarya porphyry Mo prospect is set in a back-arc geotectonic regime and shares similarities to other post-subduction porphyry molybdenum deposits elsewhere.
27
Song, Guoxue, Nigel J. Cook, Le Wang, Kezhang Qin, Cristiana L. Ciobanu, and Guangming Li. "Gold behavior in intermediate sulfidation epithermal systems: A case study from the Zhengguang gold deposit, Heilongjiang Province, NE-China." Ore Geology Reviews 106 (March 2019): 446–62. http://dx.doi.org/10.1016/j.oregeorev.2019.02.001.
Full text
28
Ajalli, N., A. Torkian, and E. Tale Fazel. "Intermediate sulfidation epithermal Cu±Au deposit of RashtAbad (North of Zanjan): evidence of mineralization, fluid inclusions and C-O stable isotope." Iranian Journal of Crystallography and Mineralogy 29, no. 1 (March 1, 2021): 207–20. http://dx.doi.org/10.52547/ijcm.29.1.207.
Full text
29
Wang, Le, Kezhang Qin, Guoxue Song, Xuyong Pang, Zhenzhen Li, Chao Zhao, Luying Jin, Xinyu Zou, and Guangming Li. "Volcanic-subvolcanic rocks and tectonic setting of the Zhengguang intermediate sulfidation epithermal Au-Zn deposit, eastern Central Asian Orogenic Belt, NE China." Journal of Asian Earth Sciences 165 (October 2018): 328–51. http://dx.doi.org/10.1016/j.jseaes.2018.07.023.
Full text
30
Verdiansyah, Okki, Arifudin Idrus, Lucas Donny Setijadji, Bronto Sutopo, and I. Gde Sukadana. "Mineralogy of hydrothermal breccia cement of Humpa Leu East porphyry copper-gold prospect, Sumbawa Island, Indonesia." E3S Web of Conferences 325 (2021): 04008. http://dx.doi.org/10.1051/e3sconf/202132504008.
Full textAbstract:
Indonesia is a country that has several world-class copper-gold deposits, particularly in eastern Sunda arc. The Hu’u complex has several prospects in the surface as lithocap of extensive epithermal style alteration, but some were detected associated with porphyry beneath the surface. The study focuses on hydrothermal breccia cement as a factor influencing the porphyry system in the Hu’u district. The methods used is mineralogical analysis with petrography and μ-XRF elemental mapping on hydrothermal breccia samples. The Hu’u district is interpreted as a paleo-volcano; a member of the Old Volcanics Rocks Formation. The Humpa Leu East lithology consists of pre-volcanics unit (lava and pyroclastics), diorite, andesite-μ-diorite, and tonalitic intrusion at the depth. Hydrothermal alteration evolved from tonalite body to outward, consist of potassic, inner propyllitic and overprinted by phyllic and advanced argillic. Several phases of hydrothermal activities occur in this system, including the hydrothermal breccia phase associated with complex fluids. The hydrothermal cement of Humpa Leu East porphyry at least have three phases of mineralogical assemblages and possibly influencing the mineralization. The mineralogical assemblage of hydrothermal cement in HLE consists of quartz-feldspar-plagioclase-biotite as a high-temperature phase; then followed by epidote-sericite-chlorites-anhydrite-carbonates in medium temperature; there are aluminum-rich clay minerals interpreted as gibbsite. Mineralization occurs in three phases including chalcopyrite-magnetite, bornite-chalcopyrite and chalcopyrite-sphalerite phases. The occurrences of chalcopyrite at all phases indicate the stability of intermediate sulfidation proses in Humpa Leu and as a possible factor to answer the abundant copper in the Hu’u hydrothermal fluid system
31
Liu, Lijuan, Jeremy P. Richards, S. Andrew DuFrane, and Mark Rebagliati. "Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia." Canadian Journal of Earth Sciences 53, no. 1 (January 2016): 10–33. http://dx.doi.org/10.1139/cjes-2015-0068.
Full textAbstract:
Newton is an intermediate-sulfidation epithermal gold deposit related to Late Cretaceous continental-arc magmatism in south-central British Columbia. Disseminated gold mineralization occurs in quartz–sericite-altered Late Cretaceous felsic volcanic rocks, and feldspar–quartz–hornblende porphyry and quartz–feldspar porphyry intrusions. The mineralization can be divided into three stages: (1) disseminated pyrite with microscopic gold inclusions, and sparse quartz–pyrite ± molybdenite veins; (2) disseminated marcasite with microscopic gold inclusions and minor base-metal sulfides; and (3) polymetallic veins of pyrite–chalcopyrite–sphalerite–arsenopyrite. Re–Os dating of molybdenite from a stage 1 vein yielded an age of 72.1 ± 0.3 Ma (published by McClenaghan in 2013). The age of the host rocks has been constrained by U–Pb dating of zircon: Late Cretaceous felsic volcanic rocks, 72.1 ± 0.6 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013); feldspar–quartz–hornblende porphyry, 72.1 ± 0.5 Ma; quartz–feldspar porphyry, 70.9 ± 0.5 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013). The mineralized rocks are intruded by a barren diorite, with an age of 69.3 ± 0.4 Ma. Fluid inclusions in quartz–pyrite ± molybdenite ± gold veins yielded an average homogenization temperature of 313 ± 51 °C (number of samples, n = 82) and salinity of 4.8 ± 0.9 wt.% NaCl equiv. (n = 46), suggesting that a relatively hot and saline fluid likely of magmatic origin was responsible for the first stage of mineralization. Some evidence for boiling was also observed in the veins. However, the bulk of the gold mineralization occurs as disseminations in the wall rocks, suggesting that wall-rock reactions were the main control on ore deposition.
32
Reich, Martin, Nelson Román, Fernando Barra, and Diego Morata. "Silver-Rich Chalcopyrite from the Active Cerro Pabellón Geothermal System, Northern Chile." Minerals 10, no. 2 (January 28, 2020): 113. http://dx.doi.org/10.3390/min10020113.
Full textAbstract:
Active subaerial geothermal systems are regarded as modern analogues of low- to intermediate-sulfidation epithermal Au–Ag deposits, where minor amounts of Cu are mostly present as chalcopyrite. Although trace element data concerning sulfides are scarce in active geothermal systems at convergent settings, studies in several other environments have demonstrated that chalcopyrite is a relevant host of Ag and other trace elements. Here, we focus on the active Cerro Pabellón geothermal system in the Altiplano of northern Chile, where chalcopyrite-bearing samples were retrieved from a 561 m drill core that crosscuts the high-enthalpy geothermal reservoir at depth. A combination of EMPA and LA-ICP-MS data shows that chalcopyrite from Cerro Pabellón is silver-rich (Ag > 1000 ppm) and hosts a wide range of trace elements, most notably Se, Te, Zn, Sb, As, and Ni, which can reach 100 s of ppm. Other elements detected include Co, Pb, Cr, Ga, Ge, Sn, Cd, and Hg but are often present in low concentrations (<100 ppm), whereas Au, Bi, Tl, and In are generally below 1 ppm. Chalcopyrite shows a distinct geochemical signature with depth, with significantly higher Ag concentrations in the shallow sample (494 m) and increasing Cd and In contents towards the bottom of the studied drill core (549 m). These differences in the trace element contents of chalcopyrite are interpreted as related to temperature gradients during the waning stages of boiling at Cerro Pabellón, although further studies are still needed to assess the precise partitioning controls. Our data provide evidence that chalcopyrite may play a relevant role as a scavenger of certain metals and a monitor of fluid changes in hydrothermal systems.
33
Zhao, Zi-Hao, Pei Ni, Zhong-Lie Sheng, Bao-Zhang Dai, Guo-Guang Wang, Jun-Ying Ding, Bo-Hua Wang, Huai-Dong Zhang, Jun-Yi Pan, and Su-Ning Li. "Thermal regime reconstruction and fluid inclusion LA–ICP–MS analysis on intermediate-sulfidation epithermal Pb–Zn veins: Implications for porphyry Cu deposits exploration in the Xianhualing District, Anhui, China." Ore Geology Reviews 124 (September 2020): 103658. http://dx.doi.org/10.1016/j.oregeorev.2020.103658.
Full text
34
Sabeva, Ralica, Vassilka Mladenova, and Aberra Mogessie. "Ore petrology, hydrothermal alteration, fluid inclusions, and sulfur stable isotopes of the Milin Kamak intermediate sulfidation epithermal Au-Ag deposit in Western Srednogorie, Bulgaria." Ore Geology Reviews 88 (August 2017): 400–415. http://dx.doi.org/10.1016/j.oregeorev.2017.05.013.
Full text
35
Chen, Xinglin, Yongjun Shao, Chunkit Lai, and Cheng Wang. "Genesis of the Longmendian Ag–Pb–Zn Deposit in Henan (Central China): Constraints from Fluid Inclusions and H–C–O–S–Pb Isotopes." Geofluids 2020 (July 13, 2020): 1–21. http://dx.doi.org/10.1155/2020/7352821.
Full textAbstract:
The Longmendian Ag–Pb–Zn deposit is located in the southern margin of the North China Craton, and the mineralization occurs mainly in quartz veins, altered gneissic wallrocks, and minor fault breccias in the Taihua Group. Based on vein crosscutting relations, mineral assemblages, and paragenesis, the mineralization can be divided into three stages: (1) quartz–pyrite, (2) quartz–polymetallic sulfides, and (3) quartz–carbonate–polymetallic sulfides. Wallrock alteration can be divided into three zones, i.e., chlorite–sericite, quartz–carbonate–sericite, and silicate. Fluid inclusions in all Stage 1 to 3 quartz are dominated by vapor-liquid two-phase aqueous type (W-type). Petrographic and microthermometric analyses of the fluid inclusions indicate that the homogenization temperatures of Stages 1, 2, and 3 are 198–332°C, 132–260°C, and 97–166°C, with salinities of 4.0–13.3, 1.1–13.1, and 1.9–7.6 wt% NaCleqv, respectively. The vapor comprises primarily H2O, with some CO2, H2, CO, N2, and CH4. The liquid phase contains Ca2+, Na+, K+, SO42−, Cl−, and F−. The sulfides have δ34S=–1.42 to +2.35‰ and 208Pb/204Pb=37.771 to 38.795, 207Pb/204Pb=15.388 to 15.686, and 206Pb/204Pb=17.660 to 18.101. The H–C–O–S–Pb isotope compositions indicate that the ore-forming materials may have been derived from the Taihua Group and the granitic magma. The fluid boiling and cooling and mixing with meteoric water may have been critical for the Ag–Pb–Zn ore precipitation. Geological and geochemical characteristics of the Longmendian deposit indicate that the deposit is best classified as medium- to low-temperature intermediate-sulfidation (LS/IS) epithermal-type, related to Cretaceous crustal-extension-related granitic magmatism.
36
Slater, Evan, Jacob Hanley, Thomas Mulja, Marcos Zentilli, and Corwin Trottier. "Epithermal Mineralization in the Busang Southeast Zone, Indonesia: New Insight into the Au Prospect at the Center of the Bre-X Fraud." Minerals 10, no. 8 (August 6, 2020): 698. http://dx.doi.org/10.3390/min10080698.
Full textAbstract:
The Busang mineral prospect in Kalimantan, Indonesia, was reported to host a large Au resource until 1997 when it was revealed that drill core samples had been deliberately and systematically contaminated (“salted”) with extraneous Au to falsify resource estimates. One month before the fraud was uncovered, Dr. G. Milligan, then professor emeritus of geology, visited the site to collect a suite of core samples for academic study that was deemed representative of the host rocks, alteration, and mineralization of the Busang Southeast Zone. These samples were re-examined here by optical microscopy, electron microprobe (EMPA), whole-rock geochemistry, and fluid inclusion microthermometry to characterize the subsurface geology and hydrothermal mineralization, and to assess reasons why the system is of uneconomic character. The host rocks were variably altered calc-alkaline porphyritic subvolcanic diorites, typical of the lithological units along the mineralized trend in the Kalimantan Gold Belt. Early hydrothermal mineralization with quartz-sulfide (pyrite, chalcopyrite, Cu-sulfosalts) stockwork veinlets associated with pervasive phyllic and propylitic alteration was overprinted by crudely banded quartz-carbonate-sulfide/sulfosalt (pyrite, sphalerite, chalcopyrite, galena, tennantite-tetrahedrite, bournonite-seligmannite) veins. The stockwork veins were associated with up to 140 ppb bulk rock Au, some of which was hosted by Cu-sulfosalts. Microthermometry on quartz-hosted aqueous fluid inclusion assemblages (FIA; n = 13) and single inclusions (non-FIA; n = 20) in quartz-carbonate-sulfide/sulfosalt veins yielded an overall range in homogenization temperatures (Th) between 179 °C and 366 °C and bulk salinities between 1.1 wt.% to 8.6 wt.% NaCl equivalent, with much smaller data ranges for individual FIA (e.g., FIA 3; 239.1 °C to 240.5 °C and 0.5 wt.% to 1.4 wt.% NaCl equivalent). Primary FIA along growth zones in quartz were identified, providing constraints on fluid characteristics at the time of quartz growth. Carbonate-hosted FIA (n = 3) and single inclusions (non-FIA; n = 3) in the same veins yielded Th between 254 °C and 343 °C and bulk salinities of 1.1 wt.% to 11.6 wt.% NaCl equivalent. Likewise, data ranges for individual FIA were much smaller. Many of the geological characteristics of the Busang Southeast Zone were compatible with a telescoped, intermediate-sulfidation epithermal system, having formed from diluted magmatic fluids that precipitated weak base metal mineralization. However, the system was unproductive with respect to Au and Ag, at least within the studied area. Of note, vein textures and fluid inclusion characteristics indicative of boiling or efficient fluid mixing—processes both considered critical for the formation of economic lode gold deposits—were absent in the samples.
37
Cabello, José. "Gold Deposits in Chile." Andean Geology 48, no. 1 (January 29, 2021): 1. http://dx.doi.org/10.5027/andgeov48n1-3294.
Full textAbstract:
A review of gold and gold bearing base metals deposits in Chile, indicate the existence of at least six different type of ore deposits, most largely formed during the Cenozoic with predominance in the Miocene. Mesozoic deposits are common but less relevant regarding their size and gold content. These hydrothermal ore deposits are genetically associated with subduction related Andean arc magmatism. Due to its relationship with episodic magmatism migrating eastward, there is a tendency for the deposits to be in distinct, north-south trending, belts with a progressive west to east decrease in mineralization age. After analysing 82 cases in total, main gold concentration can be assigned to high-sulfidation epithermal and porphyry type deposits. Low-sulfidation epithermal, IOCG and mesothermal type appears as less relevant. Gold bearing copper deposits constitute an important part of Chile’s total gold production. Both IOCG type but especially porphyry copper deposits are and will remain as a substantial source to supplement the future output of the gold in the country. The 82 deposits with their tonnage and grade studied, represent a total gold content of 11,662 t equivalent to 375 Moz, excluding past production for those exploited. A number of probable gold bearing base metals high tonnage deposits (IOCG and porphyry copper) do not include their gold content in public format, hence the number delivered could be estimated conservative. Methodical geochronological, ore types and zonation studies are required to better appreciate this metallogenic setting widening current understanding and future exploration results.
38
Setianto, A., G. Yugamaris, I. W. Warmada, and P. Bangun. "Geological structures control on the streamflow orientation pattern in the Cijulang area and its surroundings, Garut, West Java, Indonesia." IOP Conference Series: Earth and Environmental Science 851, no. 1 (October 1, 2021): 012009. http://dx.doi.org/10.1088/1755-1315/851/1/012009.
Full textAbstract:
Abstract The Cijulang area is one of the deposits included in the high sulfidation epithermal deposits in Garut Regency, West Java Province. Ore mineralization in high sulfidation epithermal deposits is closely related to the geological structure. The existence of streamflows can be used as a fundamental basis for identifying geological structures. Geological structure identification is done by classifying the orientation angle interval class in stream segments. Each grid unit in the orientation angle interval class stream segment which has the same pattern is controlled by geological factors, including geological structures or the constituent rocks. By utilizing streamflow data, Digital Elevation Model (DEM), and secondary data (e.g., geological features such as structure geology and lithology from previous research data), geological structures can be identified. Faults that can be identified are the Cikahuripan fault, Citando fault, Cisuren fault, and Cibuni fault. These faults affect streamflow by 44.54% in the research area while lithology affects 35.12% of it. The influence of lithology will be greater in lower-order stream segments and the effect of faults will be greater in high order stream segments.
39
Morishita, Yuichi, Napoleon Q. Hammond, Kazunori Momii, Rimi Konagaya, Yuji Sano, Naoto Takahata, and Hirotomo Ueno. "Invisible Gold in Pyrite from Epithermal, Banded-Iron-Formation-Hosted, and Sedimentary Gold Deposits: Evidence of Hydrothermal Influence." Minerals 9, no. 7 (July 19, 2019): 447. http://dx.doi.org/10.3390/min9070447.
Full textAbstract:
“Invisible gold” in pyrite is defined as an Au solid solution of the pyrite lattice, sub-microscopic Au nanoparticles (NPs) in the pyrite, or other chemisorption complexes of Au. Because the relationship between the Au and As concentrations in pyrite could indicate the genesis of the deposit, the purpose of this study is to assess the micro-analytical characteristics of the Au–As relationship in pyrite from epithermal and hydrothermally affected sedimentary Au deposits by secondary ion mass spectrometry. The Au and As concentrations in pyrite vary from 0.04 to 30 ppm and from 1 to 1000 ppm, respectively, in the high-sulfidation Nansatsu-type epithermal deposits; these concentrations are both lower than those of the low-sulfidation epithermal Hishikari deposit. The Au concentrations in pyrrhotite and pyrite reach 6 and 0.3 ppm, respectively, in the Kalahari Goldridge banded-iron-formation-hosted gold deposit, and Au in pyrrhotite may sometimes exist as NPs, whereas As concentrations in pyrrhotite and pyrite are both low and lie in a narrow range from 6 to 22 ppm. Whether Au is present as NPs is important in ore dressing. The Au and As concentrations in pyrite from the Witwatersrand gold field range from 0.02 to 1.1 ppm and from 8 to 4000 ppm, respectively. The shape of the pyrite grains might prove to be an indicator of the hydrothermal influence on deposits of sedimentary origin, which implies the genesis of the deposits.
40
Muhammad Muhsin Al Hakim, Arifudin Idrus, and Wiwit Suryanto. "GEOLOGY AND ORE CHARACTERISTICS OF LOW SULFIDATION EPITHERMAL GOLD MINERALIZATION AT TAMBANG SAWAH, LEBONG, BENGKULU PROVINCE." KURVATEK 7, no. 2 (November 18, 2022): 81–92. http://dx.doi.org/10.33579/krvtk.v7i2.3185.
Full textAbstract:
Abstract –– Tambang Sawah Area, Lebong Regency, Bengkulu Province, is geologically located in the Barisan mountains and Sumatra fault zone. The prospect of Tambang Sawah area lies in the physiography of the central Sumatran mountains ranges composed by the igneous rocks of the Sunda – Banda magmatic arc. This study is aimed to understand the deposit geology and ore characteristics of the gold deposit at the study area. Quartz vein mineralization of Tambang Sawah occurred in granite rock intruded into andesitic breccia rocks, with the geological structure of mineralization control in the form of joint, breccia, dike, and fault, namely the Ketahun fault that forms extentional fracture zones which were filled by hydrothermal fluid in form of quartz veins. Hydrothermal alterations that appear at the study site are typical types of alterations found in epithermal gold deposits, namely, argillic, silicified and propylitic. Sulfide minerals markers of low sulfidation epithermal type gold deposits found, namely, pyrite, calcopyrite, covelite, sphalerite and galena with colloform vein texture, cockade-crustiform, moss, and brecciated texture. Gold is interpreted to be derived from the deposition of sulfide minerals and the deposition of quartz veins, the level of gold in rocks and veins varies greatly with an average 4,8 ppm. Based on the results of ore geochemical analysis of positively correlated gold with elements Ag, Cu, Pb and Zn.
Keywords: Mineralization, low sulfidation epithermal gold, Tambang Sawah, Lebong, Bengkulu.
41
Volkov, A. V., V. Yu Prokofiev, A. A. Sidorov, S. F. Vinokurov, A. A. Elmanov, K. Yu Murashov, and N. V. Sidorova. "The conditions of formation of Au–Ag epithermal mineralization of the Amguemo-Kanchalan volcanic field (Eastern Chukotka)." Вулканология и сейсмология, no. 5 (August 15, 2019): 68–80. http://dx.doi.org/10.31857/s0203-03062019568-80.
Full textAbstract:
The article considers the conditions of formation of Au–Ag epithermal mineralization of the Amguemo-Kanchalan volcanic field (AKVP), located on the Western closure of the East Chukchi flank zone of the Okhotsk-Chukchi volcanic belt (OCHVB). In the AKVP potentially large Au–Ag Valunisty mine and several perspective deposits and ore occurrences (Zhilnoye, Shah, Gornoye, Ognennoye and Osennee) are localized. The results of thermo- and cryometric studies of fluid inclusions in quartz and calcite of epithermal veins showed that the solutions was dominated by chlorides Na and K. Epithermal mineralization was deposited by heterogeneous hydrothermal fluids with low salt concentrations (0.2–3.6 wt. % equiv. NaCl, in medium-temperature conditions – 174–354°C). The fluid pressure reached 30–160 bar, which corresponds to the formation depth of 0.1–0.6 km, under hydrostatic conditions. The obtained results allow us to attribute the studied epithermal mineralization to the low sulfidation class. The magmatic hearth of andesitic magmas and meteoric waters are the most probable sources of ore-forming fluids. The information given in the article is of practical importance for regional forecast-metallogenic constructions, prospecting and evaluation of epithermal Au–Ag deposits.
42
Gurin, G. V. "Geophysical prospecting for epithermal gold deposits (a case study from the Maletoivayam gold ore field, Kamchatka Peninsula)." LITHOSPHERE (Russia) 21, no. 1 (March 4, 2021): 116–32. http://dx.doi.org/10.24930/1681-9004-2021-21-1-116-132.
Full textAbstract:
Research subject. The high-sulfidation (HS-type) epithermal gold deposits of the Maletoyvayam ore field, which is located in the volcanic belts of the Kamchatka Peninsula. Materials and methods. The paper presents the results of geophysical and petrophysical studies carried out by “NPP VIRG-Rudgeofizika” (2016–2017 years) in the central part of the Maletoyvayam ore field hosting HS-type gold deposits. Results. The presented case study shows the potential of geophysical prospecting for HS-type epithermal gold deposits located within altered rock areas. On the basis of the conducted magnetic surveys, fragments of a ring structure broken by faults and the hydrothermally altered bodies within the Neogene volcanogenic-sedimentary sequence of the andesite composition were identified. Using the 3D inversion of magnetic data, the shape, size and structure of the hydrothermally altered bodies were estimated. The electrical survey data allowed the hydrothermally altered areas to be differentiated in terms of composition. As a result, zoning of hydrothermally altered areas was conducted, and ore-bearing sites and gold-bearing bodies of monoquartzites in the plan and cross-section were determined. Conclusions. Geophysical techniques for prospecting HS-type epithermal gold deposits are effective in distinguishing important gold-related features within the altered zone thereby facilitating identification of specific drill targets.
43
SHATWELL, D., J. A. CLIFFORD, D. ECHAVARRÍA, G. IRUSTA, and D. LOPEZ. "Discoveries of Low-Sulfidation Epithermal Au-Ag Veins at Cerro Negro, Deseado Massif, Argentina." SEG Discovery, no. 85 (April 1, 2011): 1–23. http://dx.doi.org/10.5382/segnews.2011-85.fea.
Full textAbstract:
ABSTRACT Exploration by Andean Resources Ltd. in the Cerro Negro district of southern Argentina between March 2005 and July 2010 delineated resources of 2.54 Moz gold and 23.5 Moz silver in three low-sulfidation epithermal vein deposits. Two of these, Eureka West and Bajo Negro, are new discoveries; the third deposit, Vein Zone, had been explored previously. Additional measured and indicated resources of 2.7 Moz Au have been estimated by current owners Goldcorp Inc. for three other discoveries at Cerro Negro: San Marcos, Mariana Norte, and Mariana Central. The total gold resource for the project is 5.3 Moz Au measured and indicated, plus 1.24 Moz inferred. Andean completed a positive feasibility study into an underground and open pit mining operation in July 2010, based on reserves of 2.07 Moz Au and 20.6 Moz Ag at Eureka, Bajo Negro, and Vein Zone. The study concluded that these deposits can produce an average of 200,000 oz of gold and 1.8 Moz of silver per year for 10 years, which would make Cerro Negro the largest gold producer in the Deseado Massif without considering resources or production from the other three deposits. The deposits are hosted by Late Jurassic volcanic and probable intrusive rocks of the Deseado Massif in which Triassic-Cretaceous extension created the structures which control the precious metal vein deposits. Four of the five new discoveries were found through geologic mapping, but pioneering work by previous explorers also contributed; the two most recent discoveries do not crop out. Geophysical studies helped to define drill targets and are likely to be increasingly important in future exploration. A key ingredient in Andean’s success was a willingness to drill test targets identified by a skilled and dedicated, largely Argentine, exploration team, supported by Australian and North American-based management.
44
Turner, William A., Larry M. Heaman, and Robert A. Creaser. "SmNd fluorite dating of Proterozoic low-sulfidation epithermal AuAg deposits and UPb zircon dating of host rocks at Mallery Lake, Nunavut, Canada." Canadian Journal of Earth Sciences 40, no. 12 (December 1, 2003): 1789–804. http://dx.doi.org/10.1139/e03-061.
Full textAbstract:
The Mallery Lake area contains precious metal-bearing quartzchalcedony stockworks that are pristine examples of ancient low-sulfidation epithermal deposits. Fluorite extracted from these epithermal deposits define a SmNd errorchron age of 1434 ± 23 Ma mean square of weighted deviates (MSWD) = 4.8. This date is interpreted to have age significance because (1) a simple linear trend does not exist between the 143Nd/144Nd ratios of the fluorite with respect to their 1/Nd concentrations as would be expected for mixing of two geochemical end members; (2) microthermometric studies indicate that the fluorite analysed in this study has an intimate association with a single high-salinity, calcic brinal fluid; and (3) the age determined from seven fluorite samples extracted from a single outcrop location yielded an identical age result (1434 ± 60 Ma; MSWD = 5.5) compared to the fluorite composite. Rhyodacites of the Pitz Formation and syenites from the Nueltin suite (intrusive equivalent to the rhyodacites) are the youngest volcanicplutonic rocks that are observed in outcrop in the Mallery Lake area, and they were dated by UPb zircon analysis at 1760 ± 43 Ma and 1755.4 ± 1.8 Ma, respectively. The ~320 million year age difference between the epithermal deposits and the hosting rhyodacitic flows suggests that the epithermal stockworks may have formed by a regional hydrothermal event unrelated to this earlier Paleoproterozoic volcanic activity. Uranium deposits in the Thelon and Athabasca basins, to the northwest and south of the Baker Lake Basin, were determined to have similar ore emplacement ages with no evident heat source.
45
Ernawati, Rika, Arifudin Idrus, and 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, no. 3 (September 21, 2019): 198. http://dx.doi.org/10.25299/jgeet.2019.4.3.1653.
Full textAbstract:
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.
46
Andini, D. E., and R. S. Gautama. "Prediction Potential Acid Mine Drainage of Epithermal High Sulfidation Deposits using Static Test." IOP Conference Series: Earth and Environmental Science 353 (October 31, 2019): 012023. http://dx.doi.org/10.1088/1755-1315/353/1/012023.
Full text
47
Abbasnia, Hosain, Mohammadhasan Karimpour, and Azadeh Malekzadeh Shafaroudi. "Damanghor intermediate sulfidation epithermal Au mineralization, Northern Bardaskan: geology, alteration, mineralization, and geochemistry." Iranian Journal of Crystallography and Mineralogy 27, no. 3 (October 1, 2019): 621–34. http://dx.doi.org/10.29252/ijcm.27.3.621.
Full text
48
Titisari, Anastasia Dewi, Septyo Uji Pratomo, and Arifudin Idrus. "Hydrothermal Alteration of High Sulfidation Epithermal Deposits in Secang Area, Tulungagung, East Java, Indonesia." Journal of Applied Geology 5, no. 2 (January 18, 2021): 73. http://dx.doi.org/10.22146/jag.55235.
Full textAbstract:
This research aims to determine geological condition and alteration in an epithermal high sulfidation mineralization as an initial guide for further exploration stages. Detailed geological mapping with scale of 1:12,500 is conducted to identify geological aspects and distribution of alteration zones. Selected rocks samples were prepared for laboratory analysis which are petrography, XRD (X-Ray Diffraction), and FA-AAS (Fire Assay-Atomic Absorption Spectrometry) analyse. Geological condition of the study area consists of six rock units including andesite lava, andesite breccia, diorite intrusion, polymict breccia, limestone, and alluvial deposit. Geological structures found are left strike-slip fault with right strike-slip fault as accompany. Result of XRD analysis shows the presence of clay minerals group: smectite, kaolinite, illite, diaspore, alunite, and pyrophillite. The alteration zones of study area are propylitic, argillic, advance argillic, and silisification zones. The further exploration stage is recommended to focus at the southwest and northeast of study area.
49
THOMPSON, ANNE J. B., PHOEBE L. HAUFF, and AUDREY J. ROBITAILLE. "Alteration Mapping in Exploration: Application of Short-Wave Infrared (SWIR) Spectroscopy." SEG Discovery, no. 39 (October 1, 1999): 1–27. http://dx.doi.org/10.5382/segnews.1999-39.fea.
Full textAbstract:
ABSTRACT Alteration mineral assemblages are important to the understanding of and exploration for hydrothermal ore deposits. Conventional mapping tools may not identify fine-grained minerals or define important compositional variations. Field portable short-wave infrared (SWIR) spectrometers solve some of these problems and provide a valuable tool for evaluating the distribution of alteration assemblages. Spectrometers such as the PIMA-II allow rapid identification of minerals and mineral-specific variations at a field base. Mineral assemblages, integrated with other exploration data, are then used to target drill holes and guide regional exploration programs. Data collection must be systematically organized and carried out by a trained operator. Analysis of data sets requires the use of spectral reference libraries from different geological environments and may be aided in some cases by computer data processing packages. Integration of results with field observations, petrography, and X-ray diffraction analysis is necessary for complete evaluation. The PIMA (portable infrared mineral analyzer) has been used successfully in the high-sulfidation epithermal, low-sulfidation epithermal, volcanogenic massive sulfide (VMS) and intrusion-related environments. Case studies from these systems demonstrate the ability to rapidly acquire and process SWIR data and produce drill logs and maps. The resulting information is critical for targeting.
50
Melfos, Vasilios, Panagiotis Voudouris, Todor Serafimovski, and Goran Tasev. "Fluid Inclusions at the Plavica Au-Ag-Cu Telescoped Porphyry–Epithermal System, Former Yugoslavian Republic of Macedonia (FYROM)." Geosciences 9, no. 2 (February 14, 2019): 88. http://dx.doi.org/10.3390/geosciences9020088.
Full textAbstract:
The Plavica Au-Ag-Cu porphyry and high sulfidation (HS) epithermal deposit is located at the Kratovo–Zlatovo volcanic field in Eastern Former Yugoslavian Republic of Macedonia. In this study, new fluid inclusions data provide additional evidence of the presence of a porphyry style mineralization which is associated with an overlain HS epithermal deposit. The Oligocene–Miocene magmatic rocks have a calc–alkaline to high-K calc–alkaline affinity and consist of sub-volcanic intrusions and volcanic rocks. Previous studies distinguished four alteration types: (a) Sericitic, (b) advanced argillic, (c) silicification, and (d) propylitic alteration. Fluid inclusions showed an early magmatic brine in porphyry style veins with high salinity (33–57 wt% NaCl equiv.), which coexists with a vapor rich fluid with lower salinity (14–20 wt% NaCl equiv.), at temperatures 380–500 °C, under boiling conditions. At shallower depths, the fluid inclusions demonstrate various HS–epithermal deposits which were formed by moderate to low salinity (3–14 wt% NaCl equiv.) hydrothermal fluids at lower temperatures from 200 to 300 °C.