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1
Birch, William D. "Mineralogy of the Silver King deposit, Omeo, Victoria." Proceedings of the Royal Society of Victoria 129, no. 1 (2017): 41. http://dx.doi.org/10.1071/rs17004.
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The Silver King mine (also known as Forsyths) operated very intermittently between about 1911 and the late 1940s on Livingstone Creek, near Omeo, in northeastern Victoria. The deposit consists of six thin and discontinuous quartz lodes that are variably mineralised. Assays of up to 410 ounces of silver per ton were obtained but there are only a few recorded production figures. Examination of representative ore samples shows that the main silver-bearing minerals in the primary ore are pyrargyrite, freibergite, andorite and the rare sulphosalt zoubekite, which occur irregularly with pyrite, arsenopyrite, galena and sphalerite. Phase assemblage data indicate that crystallisation occurred over an interval from about 450°C to less than 250°C, with the silver-bearing minerals crystallising at the lowest temperatures. The lodes were formed by the emplacement of hydrothermal solutions into fractures within the Ensay Shear Zone during the Early Devonian Bindian Orogeny. There are similarities in mineralisation and timing of emplacement between the Silver King lodes and the quartz-reef-hosted Glen Wills and Sunnyside goldfields 35‒40 km north of Omeo.
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Mykhailov, V., and А. Tots. "A NEW GOLD ORE REGION IN TANZANIA." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 3 (82) (2018): 55–59. http://dx.doi.org/10.17721/1728-2713.82.07.
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Tanzania is one of the leading gold mining countries in the world and the discovery of new gold resources on its territory is an actual task. Known gold deposits are concentrated mainly in the northwest of the country, in the metallogenic zone of Lake Victoria, where they are associated with the Archean greenstone belts, and to a lesser extent – in the southwest, in the ore regions of Lupa and Mpanda, confined to the Ubendian Paleoproterozoic mobile belt. With regard to the eastern regions of Tanzania, where the Proterozoic structures of the Uzagaran mobile belt are developed, until recently in this region any significant manifestations of gold mineralization were not known. As a result of our research in the northern part of the Morogoro province of the Republic of Tanzania, a new previously unknown gold deposit Mananila was discovered. It is represented by a large volume, up to 400–450 m long, up to 60–80 m thick, mineralized shear zone over intensely leached and schistosed migmatites, gneisses, amphibolites, penetrated by echelon systems of quartz veins and veinlet, steeply dipping bodies of quartz breccia up to 1.0–1.5 m thick. Gold contents range from 0.61 to 8.11 g/t, the average zone content is 2.5–3.0 g/t. Parallel to the main zone, similar structures are developed on the site, although they are of lower thickness. The forecast resources of the deposit are estimated at 20 tons of gold. 2.8 km to the east from the Mananila field, the recently discovered Mazizi gold deposit is located, and a number of small occurrences of gold are also known in the region. All these objects are located within a large shear zone of the northeastern strike, up to 4–5 km width, over 20 km in length. This serves as the basis for the identification of a new gold ore region in the northern part of the Morogoro province of the United Republic of Tanzania, within the Proterozoic mobile belt of Usagaran, the possible gold content of which has never been previously discussed in geological literature.
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Sidorov, A. A. "Xenothermal ore deposits of Northeastern Russia." Doklady Earth Sciences 433, no. 1 (July 2010): 861–65. http://dx.doi.org/10.1134/s1028334x10070032.
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Ju, Nan, Sen Zhang, Lin-Lin Kou, Hai-Po Wang, Di Zhang, Yu-Chao Gu, and Tong Wu. "Source and Tectonic Setting of Porphyry Mo Deposits in Shulan, Jilin Province, China." Minerals 9, no. 11 (October 26, 2019): 657. http://dx.doi.org/10.3390/min9110657.
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The Shulan area in Jilin Province is a part of the Lesser Xing’an–Zhangguangcai Range polymetallic ore belt, which is an important Cu–Mo ore region of northeast China. The discovery of three large Mo ore deposits (Fu’anbu, Chang’anbu, and Jidetun) highlights its potential for porphyry Mo ore deposits. Here we investigated the tectonic setting and mineralization of Mo ore deposits in the Shulan area, based on comparative study of the Fu’anbu, Chang’anbu, and Jidetun deposits. The ore-controlling structures are NE–SW- and NW–SE-trending faults. The main ore mineral in all three deposits is molybdenite. The ore bodies are all hosted in granites, have a stratiform or lenticular shape, and have strongly altered wall rocks. These observations indicate the Mo deposits in the Shulan area are typical porphyry Mo deposits. All were formed during the early Yanshanian (199.6–133.9 Ma). Biotite adamellites from the Chang’anbu deposit yield a U–Pb age of 182.10 ± 1.20 Ma. Molybdenites from the Fu’anbu and Jidetun deposits have Re–Os isochron ages of 166.9 ± 6.7 and 169.1 ± 1.8 Ma, respectively. Quartz and ore minerals were analysed for H–O and S–Pb isotopes, respectively. The results suggest the ore-forming materials were predominantly of upper-mantle origin, with secondary contributions from the lower crust. The ore-hosting granites have high concentrations of SiO2 (66.67–75.43 wt.%) and Al2O3 (12.91–16.44 wt.%), low concentrations of MgO (0.09–1.54 wt.%), and Ritman index (σ = K2O + Na2O)2/(SiO2 − 43)) ratios of 2.09–2.57. The granites are enriched in large-ion lithophile elements and depleted in high-field-strength elements, and have negative Eu anomalies. The ore-hosting rocks are geochemically similar to granites in northeastern China that were generated in a collisional orogeny. We conclude that early Yanshanian (199.6–133.9 Ma) mantle–crust-derived magmatism caused by the subduction of the Palaeo-Pacific Plate was the main source of Mo deposits in the Shulan area.
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Yang, Guang Shu, Yong Feng Yan, Peng Yu Feng, and Jun Wei Zhang. "Metallogenic Geological Conditions and Prospecting Indicators of the Carbonate-Hosted Pb-Zn Deposits in Northeastern Yunnan Province, China." Advanced Materials Research 962-965 (June 2014): 296–99. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.296.
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Based on large scale geological mapping, geological-section, tectonic and geochemical studies on the carbonate-hosted Pb-Zn deposits in NE Yunnan, the metallogenic geological conditions are discussed, and the ore-prospecting indicators are summarized. The Pb-Zn deposits have many common features, which are mainly controlled by the thrust fault-fold structures and lithological conditions. The ore-forming mechanism of them is similar to the MVT Pb-Zn deposit. The combination of thrust fault-fold structures and altered carbonate rocks with geochemical anomalies are good indicators for prospecting.
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Rich, Thomas H., Li Xiao-bo, and Patricia Vickers-Rich. "A potential Gondwanan polar Jehol Biota lookalike in Victoria, Australia." Proceedings of the Royal Society of Victoria 121, no. 2 (2009): v. http://dx.doi.org/10.1071/rs09300.
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The Early Cretaceous Jehol Biota from northeastern China has produced an abundance of well preserved birds, mammals and feathered dinosaurs, amongst other fossils. The similarities in the nature of the deposits producing these fossils to the lacustrine facies of the Strzelecki Group of southwest Gippsland, Victoria, Australia suggests that a prolonged, systematic search of those rocks in Australia could yield fossils of similar quality.
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Ganzha, О. A., Yu V. Kroshko, and H. O. Kuzmanenko. "ORE-BEARING OF THE LIVOBEREZHNY ZIRCON-RUTILE-ILMENITE PLACER DISTRICT." Geological Journal, no. 4 (December 28, 2022): 83–100. http://dx.doi.org/10.30836/igs.1025-6814.2022.4.255682.
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The relevance of the presented publication is due to the need to highlight the current state of zirconium-titanium specialization objects, the need to modernize and unify geological information, due to the significant increase in the world community’s interest in minerals that belong to the group of critical raw materials. The article presents generalized data on the ore-bearing zircon-rutile-ilmenite deposits of the Livoberezhniy placer district of the Ukrainian placer province. This area has unique paragenetic characteristics, as it is located in the junction zone of three geostructural units: the Dnipro-Donetsk depression, the northeastern slope of the Ukrainian crystalline shield, and the Kalmius-Toretsk depression of Donbas. The Livoberezhniy placer district includes the Vovchansk, Voskresenivsk, Southern, Nova-Mykolaivka, North-Samarsk, Yuriivsk and Petropavlivsk zircon-rutile-ilmenite deposits. These deposits are located in the sediments of the Bereka and Novi Petrivtsi suites. The Petropavlivsk and Yuriivsk deposits have a two-layer structure, the rest is belongs to the deposits of the only Novi Petrivtsi suite. The genesis of deposits is buried coastal-marine placers. All deposits have a slight dip of the ore sand layers in a north-east direction, which outlines the general slope of the water basin floor. Today, the Vovchansk zircon-ilmenite-rutile deposit is being developed by DEMURINSKY GZK LLC. On the basis of the results of geological prospecting and geological exploration conducted in the 60s and 70s of the last century, maps of the strength of the ore stratum and the distribution of ore components (ilmenite, rutile, zircon) were constructed. The visualization data was built for the Voskresenivsk, Southern, Nova-Mykolaivka, North-Samarsk, Yuriivsk and Petropavlivsk deposits. An analysis of the obtained data was carried out and a number of conclusions were drawn regarding the distribution of ore components for each of the deposits.
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Mykhailov, V. "ORE-MAGMATIC SYSTEM SUKUMALAND (TANZANIA)." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 1 (84) (2019): 34–41. http://dx.doi.org/10.17721/1728-2713.84.05.
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The overwhelming part of the gold ore potential of the United Republic of Tanzania is confined to the systems of the Neoarchaean greenstone belts (GSB) of the metallogenic province of Lake Victoria in the northwestern part of the country. Based on the interpretation of space imagery, in the western part of the province the Sukumaland ore-magmatic system of concentric-zonal structure has been distinguished. It is formed by a group of arched greenstone belts and associated gold deposits. They form two arcuate branches: the internal and external branch, differing in their composition and structure. The internal arc is represented by the Rwamagaza and Kahama GSB with gold deposits of Tulawaka, Buckreef, Mawe-Meru, Tembo, and Bulyanhulu. The external arc is represented by Geita and Mabale-Buhungurica GSB with gold deposits of Ridge-8, Nyankanga, Geita, Matandani, Kukuluma, Nyanzaga, Kitongo, Golden Ridge, Nyakafuru, and Miabu. Their huge gold potential (over 50 million ounces of gold) stipulates for the urgency of the study of this gigantic structure. GSB of the inner arc (Rwamagaza and Kahama) are characterized by a predominance of basic volcanic rocks, and GSB of the external arc (Geita and Mabale-Buhungurica) – by sedimentary and volcanic-sedimentary formations, in particular, banded ironstone formations (BIF). Accordingly, gold deposits of the inner arc are mainly associated with basic volcanic rocks (Tulawaka, Buckreef, Mawe-Meru, Bulyanhulu, Tembo) while gold deposits of the external arc – with BIF (Geita, Nyankanga, Kukuluma, Matandani). The nuclear part of the ore-magmatic system is of special interest, although manifestations of volcanism are absent there and gold or other mineral deposits are unknown yet, but a tectonic pattern of its structural elements indicates its significant ore potential. In particular, the presence of numerous spatially close systems of radial-circular faults attests to the presence of weakened zones in the space above the core of a hypothetical magma chamber. Gold deposits of different geological and industrial types, yet undiscovered, as well as manifestations of diatreme magmatism may be associated with these weakened zones. In particular, one cannot exclude the possible presence of diamond-bearing volcanic pipes. It is assumed that the ore-magmatic system has originated and evolved in the course of a complex multi-stage ore-magmatic process under the influence of ascending flows of depth fluids due to the long-term functioning of a zone with anomalously heated mantle in that area. During further geological exploration it is recommended to take into account the predictable availability of a single integrated ore-magmatic system of longdevelopment and its structural features.
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Milovsky, G. A., E. M. Shemyakina, and A. A. Belyakov. "Application of remote sensing for detection of zones of cataclastic and metasomatic rocks on the area of the Uvatsky ore cluster (Eastern Sayan)." Исследования Земли из Космоса, no. 1 (March 24, 2019): 47–54. http://dx.doi.org/10.31857/s0205-96142019147-54.
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Interpretation materials of the Russian space survey «Resource-P» (Geotone) in the visible and infrared bands made it possible to identify crush belts and faults of the northeastern, sublatitudinal and submeridional strike that determine the structural position of uranium mineralization within the Uvat ore cluster in the East Sayan. The principal possibility of using a high-resolution multi-zone space survey (3 m) for detecting metasomatically altered ore-bearing rocks of the Lower Proterozoic and Riphean-Paleozoic carbonate-terrigenous deposits was determined.
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Ouyang, Hegen, Jingwen Mao, and Ruizhong Hu. "Geochemistry and Crystallization Conditions of Magmas Related to Porphyry Mo Mineralization in Northeastern China." Economic Geology 115, no. 1 (January 1, 2020): 79–100. http://dx.doi.org/10.5382/econgeo.4694.
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Abstract To better understand processes leading to porphyry Mo deposit formation, the metal content, volatile content, and crystallization conditions of melt inclusions from pre- and synmineralization intrusions in six porphyry(-skarn) Mo deposits of northeastern China (Aolunhua, Hashitu, Lanjiagou, Songbei, Wanbaoyuan, and Yangjiazhangzi) were investigated by means of laser ablation-inductively coupled plasma-mass spectrometry and electron microprobe analysis. The ore-forming silicate melts were one to four times more evolved than average granite with 1 to 7 ppm Mo. The ore-related intrusions crystallized predominantly at 760° to 690°C and 3.7 to 1.0 kbar, except for the one at Hashitu, which crystallized at 770° to 740°C and lower pressures (2.0–1.0 kbar). Fertile silicate melts at Hashitu contain up to 0.4 wt % F, 0.03 to 0.09 wt % Cl, 5.0 to 7.0 wt % H2O, 10 to 24 ppm Cs, and 200 to 500 ppm Rb, whereas those at Yangjiazhangzi and Wanbaoyuan contain less Cs (3–6 ppm and 5–7 ppm, respectively), less Rb (180–220 ppm and 200–240 ppm, respectively), and negligible F (<0.15 wt %) but have similar Cl (0.03–0.05 wt %) and H2O (5.3–6.5 wt % and 4.0–5.2 wt %, respectively) contents. Calculated melt viscosities in fertile magmas (log η = 4.3–6.1 Pa s) are at the lower end of the values reported for felsic melts at the same temperature. Comparison between syn- and premineralization intrusions in individual deposits reveals that the ore-related intrusions were similarly evolved and had similar Mo contents and crystallization conditions as the nonmineralizing intrusions. The only difference is that the premineralization intrusions tend to occur as batholiths. The key to porphyry Mo mineralization lies in the focusing of fluid into and through a small rock volume on the top of the intrusion. For the studied porphyry Mo deposits, the mineralizing magmas are all Mo poor, indicating Mo enrichment is not required to form porphyry Mo deposits. Metal endowments in porphyry Mo deposits have no direct relationship with the composition and crystallization condition of mineralizing melts but are linked with the fluid flux released from the underlying magma chamber through a cupola.
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Lashko, Serhii. "Northeastern part of the Bilanivske ferruginousquartzite quarry: Risks of mining allotment." Mining of Mineral Deposits 15, no. 3 (September 2021): 54–61. http://dx.doi.org/10.33271/mining15.03.054.
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Purpose.Substantiation of the managerial decisions to minimize the risks of mining the Bilanivske ferruginous quartzite quarry on its northeastern margin. Methods. The legislative, methodological, cartographic and literary materials on the topic, as well as the area of survey have been analyzed. The necessary cartographic plotting and calculations have been performed. An abstract-logical method is used to formulate conclusions and theoretical generalizations. Findings. The ecological risks of the Bilanivske quarry northeastern margin have been substantiated: presence of uranium ore deposits and a radioactive anomaly; geochemical pollution of groundwater; a depression cone, large in area and in depth, can be formed in the region; a probability of using explosives when mining the field; use of the Bilanivske quarry eastern side for laying mine shafts and adits. The question is raised about the expected expansion of the Bilanivske quarry boundaries to the east during its mining, as well as falling into the sanitary protection zone boundaries of the northwestern residential community of the Nova Haleshchyna urban-type settlement. It is recommended, when mining the Bilanivske and Kremenchuk (Haleshchynske) iron ore deposits, to develop for them a unified draft Environmental Impact Assessment (EIA) and a unified draft of sanitary protection zone, taking into account the fact of their mutual influence on the environment. Originality.For the first time, based on a combination of geological, mining, technological and spatial factors, a site (zone) of mutual risks has been identified in the Bilanivske and Kremenchuk (Haleshchynske) iron ore deposits development. The site has an area of 165 ha, bounded by the northeastern side of the Bilanivske quarry and the southern boundary of the planned Haleshchynske mine. Practical implications.The research results can substantiate the need to resettle the residents from the northwestern residential community of the Nova Haleshchyna urban-type settlement, taking into account the Bilanivske field development by the open-pit method. In addition, they also can serve as a basis for resolving disputes between these residents and the administration of Ferrexpo Belanovo Mining LLC (Bilanivske Mining Plant).
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Pan, Zongdong, Hesheng Hou, Wei Fu, Xiaofan Deng, Jiaduo Zhang, and Hengcheng Ying. "Velocity Structure and Cu-Au Mineralization of the Duobaoshan Ore District, NE China: Constrained by First-Arrival Seismic Tomography." Minerals 12, no. 8 (July 28, 2022): 959. http://dx.doi.org/10.3390/min12080959.
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The genesis of deeply buried deposits in the Duobaoshan ore district, the largest porphyry-related Cu-Mo-Au ore field in northeastern China, is not well understood and their exploration is lacking because the fine velocity structure of this region is not comprehensively understood. Herein, first-arrival seismic travel times were picked along a deep seismic reflection profile and inverted using the tomographic method to obtain a detailed velocity profile of the upper 2900 m of the crust beneath this region. The profile showed that the velocity varied from 1900 to 6100 m/s and that the crust was subdivided into five parts by two low-velocity (2500–4000 m/s) blocks. Based on previous studies, the boundaries between the high-speed and low-speed bodies were interpreted as hidden fractures, and the 5000–6100 m/s parts were interpreted as concealed granite bodies in these sections. Porphyry copper deposits in the Duobaoshan ore district were related to the occulted granite bodies, and epithermal Au deposits were associated with the occulted fracture zones. Comprehensive evaluation of hydrothermal activity, regional magnetic anomalies, and deposit distribution indicated that the hidden fractures served as channels for ore-related magmas. Combining previous research on the Duobaoshan ore district with our results of the high-velocity interface, we infer that the prospecting range of the Tongshan deposit is below the depth of 1000 m.
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Savchuk, Yu S., A. V. Volkov, A. L. Galyamov, V. V. Aristov, I. A. Chizhova, and K. Yu Murashov. "Geological position of the gold-sulfide-quartz deposits of the Chilean active margin." LITHOSPHERE (Russia) 21, no. 2 (April 26, 2021): 222–38. http://dx.doi.org/10.24930/1681-9004-2021-21-2-222-238.
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Research subject. The gold-sulphide-quartz deposits of Central Chile are typical prospecting objects, having small ore intervals (from the first tens of centimetres to 1 m), intermittent and nested ore distribution and extremely uneven gold contents.Materials and methods. The patterns of ore mineralization distribution are considered against the background of the results of modern geophysical studies of the lithosphere: the Moho surface, density and thermal regime of the upper mantle. Detailed studies were conducted on the Yapin ore field.Results. It was shown that the faults controlling gold-sulphidequartz mineralization are derivatives of shear tectonics under the conditions of a transpression regime along the Chilean active margin. At an early stage, these faults developed in a right-shift environment, which was accompanied by the introduction of diabase dikes into the northeastern faults, and gold-sulfide-quartz mineralization superimposed on the dikes was deposited during the left-shift stage. The geological structure of the deposits in the ore field Yapin was characterized. It was shown that a diverse mineralization is developed in the ore field - copper-porphyry, IOCG-type and gold-sulphide-quartz. According to geochemical data, the latter is characterized by a clear enrichment of chalcophilic elements (Au, As, Ag, Cd, Cu, Bi, Pb, Zn, Te, Co). The marked enrichment of Bi, Te and Co ores indicates the participation of magmatic fluid in ore formation and the similarity of the mineralization of the Escondida deposit with the type of gold deposits associated with granitoid intrusions. According to geochemical features, gold-sulphide-quartz mineralization in the general zoning pattern occupies a boundary position between IOCG-type objects and copper-porphyry deposits.Conclusions. The conclusion is drawn about the independence of gold-sulphide-quartz mineralization and its difference from epithermal gold deposits. It is noted that, in the volcanic belts of the North-East of Russia, the prospects for discovering unconventional gold-sulphidequartz deposits similar to those of Central Chile are rather real.
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Yarboboev, T., Sh Sultanov, and I. Ochilov. "Main Dike Swarm of the Northern Part of the Chakylkalyan Megablock and Their Potential Ore Content (On the Example of the Yakhton Dike Swarm, Southern Uzbekistan)." Bulletin of Science and Practice 6, no. 11 (November 15, 2020): 104–16. http://dx.doi.org/10.33619/2414-2948/60/10.
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The study of mineralogical and geochemical properties of gold deposits is an urgent task for the geological industry, especially in the new areas under study. Without reliable information about the geological factors that lead to the formation of ore deposits and the mechanisms of deposit accumulation, it is impossible to ensure reliable scientific forecasting of the mineral potential of the regions, the effective creation of mineral resources of enterprises and mining, the stable operation of the mining industry. Our study of gold deposits was aimed at understanding these important issues of the ore formation problem. This is the urgency of the case. The role of the dictators of the Yakhton ore deposit as important structural material and mineral components of the leading types of ore-magmatic systems is being assessed. A peculiar feature of the geological structure of the ore area is the close paragenetic relationship of mineralization by rocks of the dike kids complex. Mineralization is localized in two stages and has bimetallic properties (gold, tungsten). The mineralization in the upper layer is localized in the corpus carbonate rocks of Yakhton (mainly garnet-pyroxene content). In the lower stage, mineralization is governed by a northeastern tectonic attenuation zone, which includes area concentrations of Au and W and areal mineralized zones that are part of the dike of the Yakhton region. Determining the spatial, age, and genetic relationships of mineralization with magmatism is a major problem of metallogeny.
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Serov, Pavel A. "Paleoproterozoic Pt-Pd Fedorovo-Pansky and Cu-Ni-Cr Monchegorsk Ore Complexes: Age, Metamorphism, and Crustal Contamination According to Sm-Nd Data." Minerals 11, no. 12 (December 13, 2021): 1410. http://dx.doi.org/10.3390/min11121410.
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This paper continues the Sm-Nd isotope geochronological research carried out at the two largest Paleoproterozoic ore complexes of the northeastern Baltic Shield, i.e., the Cu-Ni-Cr Monchegorsk and the Pt-Pd Fedorovo-Pansky intrusions. These economically significant deposits are examples of layered complexes in the northeastern part of the Fennoscandian Shield. Understanding the stages of their formation and transformation helps in the reconstruction of the long-term evolution of ore-forming systems. This knowledge is necessary for subsequent critical metallogenic and geodynamic conclusions. We applied the Sm-Nd method of comprehensive age determination to define the main age ranges of intrusion. Syngenetic ore genesis occurred 2.53–2.85 Ga; hydrothermal metasomatic ore formation took place 2.70 Ga; and the injection of additional magma batches occurred 2.44–2.50 Ga. The rock transformation and redeposited ore formation at 2.0–1.9 Ga corresponded to the beginning of the Svecofennian events, widely presented on the Fennoscandian Shield. According to geochronological and Nd-Sr isotope data, rocks of the Monchegorsk and the Fedorovo-Pansky complexes seemed to have an anomalous mantle source in common with Paleoproterozoic layered intrusions of the Fennoscandian Shield (enriched with lithophile elements, εNd values vary from −3.0 to +2.5 and ISr 0.702–0.705). The data obtained comply with the known isotope-geochemical and geochronological characteristics of ore-bearing layered intrusions in the northeastern Baltic Shield. An interaction model of parental melts of the Fennoscandian layered intrusions and crustal matter shows a small level of contamination within the usual range of 5–10%. However, the margins of the Monchetundra massif indicate a much higher level of crustal contamination caused by active interaction of parental magmas and host rock.
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Takagi, T., S. M. Koh, M. S. Song, M. Itoh, and K. Mogi. "Geology and properties of the Kawasaki and Dobuyama bentonite deposits of Zao region in northeastern Japan." Clay Minerals 40, no. 3 (September 2005): 333–50. http://dx.doi.org/10.1180/0009855054030177.
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AbstractThe Kawasaki and Dobuyama bentonite deposits in northeastern Japan show contrasting properties even though they are only 5 km apart in a sequence of Neogene sedimentary and pyroclastic rocks. The Kawasaki deposit consists of stratiform bentonite layers up to >50 m thick, and its wall rocks are unaltered shallow marine sedimentary rocks. In contrast, the Dobuyama deposit consists of a funnel-shaped ore body 200 m across, and its wall rocks are hydrothermally altered terrestrial rhyolitic pyroclastic rocks. The Kawasaki and Dobuyama bentonites mainly consist of Na-Ca smectite and Ca smectite, respectively, with subordinate opal-CT, quartz and zeolite. The geological occurrences of the deposits and wall-rock properties suggest that the Kawasaki and Dobuyama deposits were probably formed by diagenesis and low-temperature hydrothermal alteration, respectively. The difference in exchangeable cation ratios of the smectite between the two deposits is attributable to the difference in their sedimentary environments and/or burial depth.
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Milovsky, G. A., and A. A. Belyakov. "Application of remote sensing for detection of tectonic structures and localisation of ore deposits within Biryusinsky and Krepsky-Tumanshetsky ore clusters (Eastern Sayan)." Исследования Земли из Космоса, no. 3 (June 20, 2019): 55–65. http://dx.doi.org/10.31857/s0205-96142019355-65.
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As a result of decoding of the materials of the Russian space survey “Resource-P” (ShMSA) on Biryusinskaya area, the features of the tectonic structure of the horst-anticlinal uplifts and the graben-synclines separating them were determined, the large role of sublatitudinal disjunctions was shown in the structural diagram of the area under study, ore prospective sites were isolated. The study of the Krepsko-Tumanshetskaya area was carried out using space multispectral and panchromatic high-resolution surveys “Resource-P” (Geoton), which made it possible to determine the structural position of the ore deposits. On the Krepsko-Tumanshetskaya area, the ore-controlling structures are small along the length of sublatitudinal strike faults and the nodes of their intersection with the northwestern and northeastern disjunctions.
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Fluet, D. W., A. Changkakoti, R. D. Morton, J. Gray, and H. R. Krouse. "The genesis of the Deer Trail Zn–Pb–Ag vein deposits, northeast Washington, U.S.A.: evidence from fluid-inclusion and stable-isotope studies." Canadian Journal of Earth Sciences 24, no. 8 (August 1, 1987): 1715–26. http://dx.doi.org/10.1139/e87-164.
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The Zn–Pb–Ag-bearing vein deposits of the Deer Trail mine, northeastern Washington, U.S.A., are hosted by Beltian metasediments that have been intruded by the Jurassic–Cretaceous Loon Lake granitoid batholith.Vein infilling took place in three stages: pre-ore, ore, and post-ore. Fluid-inclusion studies revealed homogenization temperatures and salinities of approximately 300 °C and 6.5–8.5 wt. % NaCl equivalent, respectively, for the pre-ore stage; 250–150 °C and 4–7.5 wt. % NaCl equivalent for the ore stage; and less than 150 °C and 3 wt. % NaCl equivlent for the post-ore stage. The calculated δ18O values of the hydrothermal fluids and δD values of fluid inclusion waters were +8 to +11‰ (SMOW) and −128 to −134‰ (SMOW), respectively, for the pre-ore stage; 0 to +10‰ and −89 to −143‰ for the ore stage; and 0 to −5‰ and −139‰ for the post-ore stage. The δ34S(ΣS) of the hydrothermal fluids was approximately +10‰(CDT).The results provide insight into the evolution of a geothermal system dominated by meteoric waters and driven thermally by the cooling batholith. The chemical and isotopic compositions of the veins were influenced by chemical reactions and isotope exchange of the hydrothermal fluids with the Precambrian metasedimentary rocks.
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Bierlein, F. P., and N. J. McNaughton. "Pb isotope fingerprinting of mesothermal gold deposits from central Victoria, Australia: implications for ore genesis." Mineralium Deposita 33, no. 6 (October 1, 1998): 633–38. http://dx.doi.org/10.1007/s001260050178.
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Serov, Pavel A. "Selective Neodymium Enrichment of Sulfides as a “Fingerprint” of Late Processes of Ore-Formation: Insight into Sm-Nd Isotopes for Sulfides from Magmatic Cu-Ni-PGE Complexes and Hydrothermal Pb-Zn, Au-Mo, and Gold Deposits." Minerals 12, no. 12 (December 19, 2022): 1634. http://dx.doi.org/10.3390/min12121634.
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The effect of enrichment with Nd in sulfides from magmatic Cu-Ni-PGE complexes and sulfide ores from hydrothermal Pb-Zn, Au-Mo, and gold deposits was found and characterized. This paper concerns the report and analysis of isotopic geochemical data on the sulfide ores from the large Paleoproterozoic mafic–ultramafic magmatic Cu-Ni-PGE complexes of Fennoscandia and the literature data on sulfide ores from the Qingchengzi Pb-Zn deposit (northeastern China), Tokuzbay gold deposit (southern Altai, northwestern China), and Dahu Au-Mo deposit (central China). The mineral/rock partition coefficients for Nd and Sm (the DNd/DSm ratio) are defined as a prospective tool for the reconstruction of the sulfide mineral formation and geochemical substantiation of possible sources of ore-forming fluids for deposits of various genetic types. The observed selective Nd accumulation indicates either hydrothermal or metamorphic (metasomatic) impact, which is associated with increased Nd mobility and its migration or diffusion. Due to this process, there is a relative Nd accumulation in comparison with Sm and a consequent increase in the DNd/DSm ratio. At the isotopic system level, this leads to a sufficient decrease in the Sm/Nd ratio for the secondary sulfides of such kind. The revealed effect may serve as an isotopic geochemical marker of recent processes. These processes are quite frequently associated with the most important ore formation stages, which bear the commercially valuable concentrations of ore components. Sulfides from magmatic Cu-Ni-PGE complexes are more characterized by the selective accumulation of Nd in the sequential sulfide mineral formation. For sulfides from hydrothermal deposits, the effect of Nd enrichment is more intense and closely related to ore-forming fluids, under the influence of which sulfide mineralization is formed in multiple stages. The study aims at expanding the knowledge about fractionation and the behavior of lanthanides in ore-forming processes and allows the development of additional criteria for the evaluation of the ore potential of deposits with different geneses, ages, and formation conditions.
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Naranjo Sierra, Edwin. "Ore-controlling structures and geostatistical determination of ore-shoots in shear zone hosted lode gold type deposits, El Bagre-Antioquia, Colombia." Earth Sciences Research Journal 26, no. 1 (May 11, 2022): 47–54. http://dx.doi.org/10.15446/esrj.v26n1.92419.
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Shear zone hosted lode gold type deposits at the El Bagre in the northeastern zone of Antioquia department of Colombia, are the only evidence of Permian gold mineralization to date in Colombia Andes. Orebodies at the El Bagre are structurally controlled and are considered as the product of ore-forming fluids derived from at least two episodes of fluid flow between the shear zones, thus different fluid flow could lead to orebodies and ore shoots plunge in different directions. The La Ye orebodies tend to strike to the NNW-NS and plunge to the SW, Mangos orebodies tend to strike (as a whole) to the NS-NNE and plunge to the NE and Cordero orebodies tend to strike (as a whole) to the NNW-NS and plunge to the NE. The ellipses determined by variogram modelling for these orebodies, reveal the anisotropy of gold mineralization and therefore the orientation of ore-shoots. The long axes of the anisotropy ellipses trend SSE. These high grades distributions are related to sinistral shearing and NNW-SSE faulting during D3 deformation event. This study exemplifies a simple and effective tool for exploration strategies regarding of orebodies, ore-shoots and ore-controlling structures relationships
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Khuong, Hung The, Ta Dinh Tung, Do Quoc Binh, Pham Nhu Sang, Nguyen Thi Cuc, Nguyen Thi Hoang Linh, and Quach Duc Tin. "Sulfur and lead isotope geochemical characteristics of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam, and their significance." Geology, Geophysics and Environment 47, no. 3 (December 1, 2021): 143–57. http://dx.doi.org/10.7494/geol.2021.47.3.143.
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In northeastern Vietnam, the Khau Loc zone is considered to have high potential for lead-zinc mineralization. The lead isotope data for 18 galena samples and 18 ones of δ34S isotope data (including galena and pyrite samples) were collected from lead-zinc ore deposits in some areas in the Khau Loc zone, including Phia Dam, Khuoi Man, Ban Lin, Lung Dam, and Ta Pan. These were employed to investigate the sulfur and lead isotope geochemical characteristics of Pb-Zn deposits and their significance in this study. The samples were analyzed using the LA-ICP-MS to show that the Pb isotopic ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in the galena samples range from 17.8908 to 18.6012, 15.5794 to 16.1025, 38.4420 to 39.2118, with the average values of 18.296, 15.749, and 38.812, respectively. The pyrite and galena samples had the δ34S isotope, ranging from 9.0 to 15.106. The sulfur isotope systematics implies that most of the lead-zinc ore formations originated from marine sedimentary evaporation deposits and magmatic intrusion-volcanic eruption sources rich in silica. The distribution of lead isotopic ratios had a well-defined cluster for each deposit, indicating the formation of lead-zinc deposits and lower crust and orogen trends. In addition, these findings of lead isotopic ratios and δ 34S isotopes proved that the Khau Loc zone is an activated structure with continuous growth in continental crust thickness during the early Proterozoic and Cenozoic periods. Furthermore, the study results also presented the evolution of material sources involved in the formation of lead-zinc ores in the Khau Loc zone.
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Hou, Dongzhuang, Shu Lin, Lang Liu, Chao Huan, Huafu Qiu, and Bingbing Tu. "Metal Source and Fluid Evolution in Xiaojiashan Gold Deposit in Northeastern Hunan, China: Implications of Rare Earth Elements, Fluid Inclusions, and Pyrite S Isotopic Compositions." Minerals 13, no. 1 (January 13, 2023): 121. http://dx.doi.org/10.3390/min13010121.
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The material source and the evolution of ore-forming hydrothermal fluids of Xiaojiashan gold deposits remain controversial. We carried out a mineralogical characteristics analysis, trace elements analysis, sulfur isotope composition analysis, and fluid inclusion microthermometry in order to explore the ore-forming sources, conditions, and process of this deposit. Gold mineralization can be divided into three stages: the quartz-pyrite stage, the quartz-polymetallic sulfide stage, and the quartz-ankerite stage. This gold deposit was probably formed under the following conditions: temperature of 122–343 °C and salinity of 0.8–11.4 wt% (NaCl). It was inferred that the ore-forming hydrothermal fluids were early metamorphic–hydrothermal (Stage I) and late magmatic–hydrothermal (Stages II and III), and were characterized by medium–low temperature and medium–low salinity based on fluid inclusion microthermometry and S isotope composition. The temperature and salinity of the ore-forming fluid decreased during mineralization, which was caused by the involvement of groundwater. The chondrite-normalized trace element patterns of the gold ores are similar to the host rocks of the Lengjiaxi Formation, indicating that the ore-forming materials were sourced from the Lengjiaxi Formation. The S isotopes indicated that the magmatic components also provided the ore-forming materials during Stages II and III.
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Zhai, Degao, Anthony E. Williams-Jones, Jiajun Liu, David Selby, Panagiotis C. Voudouris, Stylianos Tombros, Kuan Li, Peilin Li, and Hongjun Sun. "The Genesis of the Giant Shuangjianzishan Epithermal Ag-Pb-Zn Deposit, Inner Mongolia, Northeastern China." Economic Geology 115, no. 1 (January 1, 2020): 101–28. http://dx.doi.org/10.5382/econgeo.4695.
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Abstract The newly discovered Shuangjianzishan Ag-Pb-Zn deposit, with 145 Mt of ore grading 128.5 g/t Ag (locally up to 32,000 g/t) and 2.2 wt % Pb + Zn, is located in the Great Hinggan Range metallogenic belt, northeastern China, and is currently the largest Ag deposit in Asia. The Ag-Pb-Zn orebodies occur as veins and are hosted primarily by a Permian slate. Recent drilling and core logging have identified a partially Mo mineralized granite porphyry intrusion adjacent to the Ag-Pb-Zn mineralized veins. This well-preserved magmatic-hydrothermal system therefore offers an excellent opportunity to evaluate the possible temporal and genetic relationship between Mo-mineralized porphyry intrusions and Ag-Pb-Zn veins. Three primary paragenetic stages of veining have been recognized: (I) early pyrite + quartz ± K-feldspar, (II) main ore sulfide + sulfosalt + quartz + calcite + sericite + chlorite ± epidote, and (III) post-ore quartz. The silver mineralization occurs mainly in the late paragenetic part of Stage II, in which canfieldite (Ag8SnS6), argentite (Ag2S) and freibergite [(Ag, Cu)12Sb4S13] are the dominant Ag-bearing ore minerals. A combination of ore mineral chemical and sulfur isotope geothermometers and physicochemical calculations suggest that the Ag-Pb-Zn mineralization took place at a temperature of 250° to 200°C, a pH of 6.7 to 5.6, and a Δlogfo2 (HM) of –2.4 to –8.7. A conspicuous enrichment of Sn and Se in the ore, which is represented by minerals containing the metal suite Ag-Pb-Zn-(Cu-Sn-Se-Sb), likely reflects a close genetic association between the base metal mineralization and a magma. In situ analyses show that the δ34S values of the sulfides and Ag-bearing sulfosalts from the Ag-Pb-Zn mineralized veins vary from –4.67 to +2.44‰; the mean value is –2.11 ± 1.49‰ (n = 77). The calculated mean δ34SH2S value of the ore-forming fluid is –1.65 ± 0.83‰, which is indicative of a magmatic sulfur source. In situ Pb isotope analyses of the ore minerals yielded a narrow range of values (206Pb/204Pb of 18.243–18.310, 207Pb/204Pb of 15.503–15.563 and 208Pb/204Pb of 38.053–38.203, n = 59). Comparisons to corresponding isotopic data for the various rock units in the area and sulfides from nearby ore deposits indicate that there were substantial contributions of Pb and other metals (e.g., Ag and Zn) to the Shuangjianzishan deposit from a Mesozoic granitic source. Diorite-granodiorite dikes and dacite are crosscut by the Ag-Pb-Zn veins, and therefore, predate ore formation. These rock units have zircon U-Pb ages of 250.2 ± 2.0 and 133.9 ± 1.4 Ma, respectively. A concealed, weakly Mo mineralized granite porphyry intrusion proximal to the Ag-Pb-Zn mineralized vein system yielded zircon U-Pb ages of 134.4 ± 1.0 (MSWD = 0.1) and 134.4 ± 1.0 Ma (MSWD = 0.2), for coarse- and fine-grained facies, respectively. These ages are indistinguishable within the uncertainty from the zircon ages for the dacite and a granite intrusion ~2 km north of the mineralized veins, which has a weighted mean zircon U-Pb age of 135.2 ± 1.4 Ma (MSWD = 0.78). Molybdenite from three quartz vein/veinlet samples hosted by slate immediately above the porphyry intrusion yielded Re-Os model ages from 136.3 ± 0.9 to 133.7 ± 1.2 Ma and a weighted mean Re-Os age of 134.9 ± 3.4 Ma. Finally, three pyrite samples separated from the Ag-Pb-Zn mineralized veins have a weighted mean Re-Os model age of 135.0 ± 0.6 Ma. The very similar zircon U-Pb ages for the Mo-mineralized granite porphyry and dacite, and Re-Os ages for molybdenite and pyrite in the Shuangjianzishan ore district indicate that the Mesozoic magmatic-hydrothermal activity was restricted to a relatively short time interval (~136–133 Ma). They also suggest that the weakly Mo mineralized granite porphyry was likely the source of the fluids and metals that produced the Ag-Pb-Zn mineralization. Based on our geological observations and an extensive analytical database, a model is proposed for the genesis of the giant Shuangjianzishan Ag-Pb-Zn deposit in which the ore-forming fluid and its metals (i.e., Ag, Pb, and Zn) were exsolved during crystallization of the final phase of a composite granite porphyry intrusion. This fluid transported metals to the distal parts of the system, where they were deposited in preexisting faults or fractures created by the withdrawal of magma during the waning stages of the magmatic-hydrothermal event. The present study of the Shuangjianzishan Ag-Pb-Zn deposit and those of other magmatic-hydrothermal ore deposits in the region provide compelling evidence that the widespread Mesozoic felsic magmatism and Ag-Pb-Zn mineralization in the southern Great Hinggan Range took place in an intracontinental extensional tectonic setting, which was synchronous with, and spatially associated to, Paleo-Pacific slab rollback and lithospheric delamination and thinning.
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YANG, Guangshu, Hanjie WEN, Yongfeng YAN, Pengyu FENG, and Junwei ZHANG. "Ore-Forming Age and Geodynamical Settings of the Carbonate-Hosted Pb-Zn Deposits in Northeastern Yunnan, China." Acta Geologica Sinica - English Edition 88, s2 (December 2014): 233–34. http://dx.doi.org/10.1111/1755-6724.12369_43.
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Karpov, I. K., R. G. Kravtsova, K. V. Chudnenko, and M. V. Artimenko. "A physicochemical model for the volcanic hydrothermal ore-forming system of epithermal gold–silver deposits, Northeastern Russia." Journal of Geochemical Exploration 69-70 (June 2000): 323–25. http://dx.doi.org/10.1016/s0375-6742(00)00133-3.
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Kuleshov, V. N., A. I. Brusnitsyn, and E. V. Starikova. "Manganese deposits in northeastern European Russia and the Urals: Isotope geochemistry, genesis, and evolution of ore formation." Geology of Ore Deposits 56, no. 5 (September 2014): 380–94. http://dx.doi.org/10.1134/s1075701514050067.
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Zhang, Yong, Jing-Gui Sun, Shu-Wen Xing, and Zeng-Jie Zhang. "Geochronology and geochemistry of the Cuihongshan Fe-polymetallic deposit, northeastern China: implications for ore genesis and tectonic setting." Canadian Journal of Earth Sciences 55, no. 5 (May 2018): 475–89. http://dx.doi.org/10.1139/cjes-2017-0178.
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The Lesser Xing’an Range is located in the eastern segment of the Central Asian Orogenic Belt. It hosts an important polymetallic metallogenic belt that contains more than 20 large- to small-scale porphyry Mo, epithermal Au, and skarn Fe-polymetallic deposits. The Cuihongshan Fe-polymetallic deposit is one of the largest polymetallic deposits in northeastern China. To better understand the formation of the Cuihongshan Fe-polymetallic deposit, we investigated the geological characteristics of the Cuihongshan deposit and applied geochemistry and geochronology to constrain the timing of the mineralization, and characteristics of the magmas. Zircon U–Pb dating of the alkali-feldspar granite and monzogranite yielded weighted mean 206Pb/238U ages of 495 ± 1.6 and 203 ± 1 Ma, respectively. Re–Os dating on molybdenite yielded an isochron age of 203.2 ± 1.4 Ma, and 40Ar/39Ar dating on phlogopite yielded an age of 203.4 ± 1.3 Ma. These data suggest that mineralization occurred during the Late Triassic, and is closely related with the monzogranite emplacement. These rocks belong to the high-K calc-alkaline and subalkaline series, are enriched in Rb, U, and Th, are depleted in Nb, Ta, and Ti, and show strong Eu anomalies, implying that they are A-type post-orogenic rocks. The Cuihongshan Fe-polymetallic formation is possibly related to an extensional environment resulting from the final closure of the Paleo-Asian Ocean.
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Fridovsky, Valery Y., and Maxim Kudrin. "Ore Geology, RE–OS Isotope Geochemistry of the Au and Au-Sb Mineralizations, Kular–Nera Terrane, Northeast Asia: Implications for Time of Formation and Ore Genesis." IOP Conference Series: Earth and Environmental Science 906, no. 1 (November 1, 2021): 012011. http://dx.doi.org/10.1088/1755-1315/906/1/012011.
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Abstract The paper presents the first results of investigation of the Re–Os isotope system of native gold from the Malo-Tarynskoe, Khangalas, Bazovskoe, and chalcopyrite from the Dvoinoe orogenic gold deposits and stibnite from the Maltan Au-Sb depositin the Kular–Nera terrane, Northeast Asia. The deposits are spatially related to NW-trending lithospheric-scale major brittle faults or controlled by subsidiary faults and fracture zones. Such zones served as pathways for fluids rising from below the crust, and they have a long tectonic and reactivation history. The Kular–Nera terrane consists of Upper Permian, Triassic, and Lower Jurassic clastic sedimentary-rock sequences, metamorphosed to initial stages of greenschist facies. Magmatism is manifested by Kimmeridgian–Berriasian S- and I-types granitoids and mafic dikes of the Tas–Kystabyt magmatic belt. Re concentration in gold varies from 0.168 to 6.997 ppb, and that of osmium – from 0.068 to 1.443 ppb. Chalcopyrite from the Dvoinoe deposit occurrence contains 0.1522 ppb Re and 0.499 ppb Os. Stibnite from the Maltan Au-Sb depositoccurrence contains 0. 236 ppb Re and 0.903 ppb Os. The Re–Os ages of gold from the Malo-Tarynskoe (147.8 ± 3.8 Ma) and Bazovskoe (147.2 ± 1.8 Ma) and Khangalas (137.1 ± 7.6 Ma) orogenic deposits and the Maltan Au-Sb deposits (69.7±1.9 Ma) are determined. Malo-Tarynskoe and Bazovskoe represent the earliest known orogenic gold mineralization in the Kular–Nera terrane. The data obtained permit us to correlate the initiation of orogenic gold-ore systems with the completion of the formation at the end of the Late Jurassic Uyandina–Yasachnaya volcanic belt, crystallization and subsequent cooling in the Late Jurassic–early Early Cretaceous of granitoid massifs of the Tas-Kystabyt magmatic belt, and subduction–accretionary events at the northeastern active continental margin of the Siberian craton. Maltan Au-Sb deposit is related to completion of the formation of the Albian-Late Cretaceous Okhotsk–Chukotka volcano-plutonic belt. Contrasting mantle and/or crustal sources of ore-forming material are established. The osmium initial isotopic ratio in gold 187Os/188Os = 0.2210-0.4275 and antimonite (0,2543-0,2976) is typical for the ore-forming material from the fertile mantle reservoir, and for chalcopyrite (3.1904) – from the crust.
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Gauthier, Michel, and Francis Chartrand. "Metallogeny of the Grenville Province revisited." Canadian Journal of Earth Sciences 42, no. 10 (October 1, 2005): 1719–34. http://dx.doi.org/10.1139/e05-051.
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Four new petrogenetic and metallogenic models are proposed herein to explain the formation of important mineral deposits in the Grenville Province, providing a framework from which to reappraise Grenvillian mineral potential. Recognition of a high-pressure metamorphic belt within the Grenville Province suggests a potential for eclogite-hosted rutile deposits, an important and much-sought commodity. A recently developed Norwegian model proposes that anorthosite genesis occurred through lower crust underplating and coeval partial melting, rather than by plume magmatism. Applied to the Grenville Province, the new petrogenetic model may provide insight into the widespread occurrence of platinum group element (PGE) poor nickel showings and the distribution of chromite, Ti-rich, and low-Ti iron-oxide deposits within the Grenville and adjacent terranes. A new type of sedimentaryexhalative (SEDEX) mineralization formed by oxidized brines has been defined following the discovery of new deposits in Australia. Applied to the Grenville Province, it provides a possible explanation for two long-recognized features of marble-hosted zinc deposits: (i) the presence of meta-siderite beds occurring as distal haloes around SEDEX zinc deposits, and (ii) the mutually exclusive division of these SEDEX deposits into massive sulphide and nonsulphide groups. The discovery of the giant Olympic Dam iron-oxide coppergold (IOCG) deposit in Australia renewed the interest in magmatic low-Ti iron-oxide deposits in the Grenville Province that have been known and mined since early colonial times. Subsequent exploration in the northeastern part of the Grenville Province revealed the presence of breccia-hosted CuAuU rare-earth element (REE)-bearing iron-oxide mineralization. This deposit and other low-Ti iron-oxide deposits in the southwestern Grenville Province have a previously undocumented close spatial and temporal association with Ti-rich iron-oxide deposits. These examples demonstrate how new petrogenetic, tectonic, and ore deposit models developed in unmetamorphosed rocks can be successfully adapted to high-grade terranes, where they stimulate mineral exploration in these challenging conditions. Furthermore, by tracking the formation of ore deposits in the lower crust, the existence of unsuspected metallogenic associations in the higher crust, such as the low-Ti and high-Ti iron-oxide association observed in the Grenville Province, may be revealed.
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Rubtsov, Yury, Aleksandr Lavrov, Aleksandr Petukhov, Mikhail Kostromin, and Aleksandra Lavrik. "Test laboratory studies of refractory gold-bearing ores of Magadan Region from the standpoint of their processing by heap leaching." E3S Web of Conferences 192 (2020): 02015. http://dx.doi.org/10.1051/e3sconf/202019202015.
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The main prospects for the development of gold mining in the Kolyma area are associated with the development of ore deposits. In the southwestern part of the Tenkinsk District and in Susuman District, there are gold deposits (Pavlik, Natalka and Degdekan), which belong to the low-sulfide formation. There are some areas of poor oxidized and low-sulphide ores, the concentration of which by gravity and flotation methods becomes ineffective. At present, at the level of laboratory research and experimental field tests, some low-cost technologies for rapid and activated heap leaching of gold from poor oxidized and low sulfide ores have been developed, and they are capable to be implemented in the harsh conditions of Magadan Region. This paper describes laboratory tests of 2 types of ores from deposits in the northeastern part of Magadan Region, carried out to develop an effective cyanide technology for gold heap leaching. The studies were carried out in the laboratory of the Insitute of Mining of FarEastern Branch of the Russian Academy of Sciences and Transbaikal State University.
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Aliyev, Anvar. "Technogenic wastes and ecological problems." Scientific Bulletin 3 (2020): 61–65. http://dx.doi.org/10.54414/qmce3105.
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The northeastern part of the Lesser Caucasus encompasses the western part of the Republic of Azerbaijan and is characterized with a prevalence of unique flora and fauna and the availability of rich natural resources, particularly metals. It is known that the long-term exploitation of these resources by surface mining has led to technogenic contamination in the area. Exploitation of ore deposits is associated with the origination of huge hills of waste which cause heavy degradation of pastures, forests, and croplands. A significant part of widely degraded areas in the northeastern Lesser Caucasus is found in the territory of the Gedabek administrative district. This paper deals with the problem of restoration for contaminated lands formed due to raw material extraction on territory of valuable mountain forests and meadows over a long historical period as well as the use of collected technogenic wastes for different purposes (e.g. in land reclamation, construction of motorways etc.).
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WANG, Zhilin, Deru XU, Teng DENG, Junling ZHANG, Juntao NING, and Guocheng HU. "Geological Characteristics and Metallogenesis of the Co-Cu Ore Deposits in the Northeastern Hunan Province of South China." Acta Geologica Sinica - English Edition 88, s2 (December 2014): 1677–78. http://dx.doi.org/10.1111/1755-6724.12385_37.
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García-Alonso, Donají, Carles Canet, Eduardo González-Partida, Ruth Esther Villanueva-Estrada, Rosa María Prol-Ledesma, Pura Alfonso, Juan Antonio Caballero-Martínez, and Rufino Lozano-Santa Cruz. "The Cretaceous sediment-hosted copper deposits of San Marcos (Coahuila, Northeastern Mexico): An approach to ore-forming processes." Journal of South American Earth Sciences 31, no. 4 (April 2011): 432–43. http://dx.doi.org/10.1016/j.jsames.2011.02.012.
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Chugaev, A. V., A. A. Nosova, S. S. Abramov, I. V. Chernyshev, N. S. Bortnikov, Yu O. Larionova, Yu V. Goltsman, G. V. Moralev, and A. A. Volfson. "Early Permian stage of formation of gold-ore deposits of northeastern Transbaikalia: Isotope-geochronological (Rb-Sr and 39Ar-40Ar) data for the Uryakh ore field." Doklady Earth Sciences 463, no. 2 (August 2015): 855–59. http://dx.doi.org/10.1134/s1028334x1508019x.
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Tolstov, Alexander, Vladimir Cherenkov, and Leonid Baranov. "GENESIS AND AGE OF THE TOMTOR Nb AND RARE-EARTH DEPOSIT ORE SEQUENCE, NORTHEASTERN SIBERIAN PLATFORM." Ores and metals, no. 4 (February 2, 2021): 32–44. http://dx.doi.org/10.47765/0869-5997-2020-10026.
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The northeastern Siberian platform (Republic of Sakha, Yakutia) hosts the Udzhinskaya province of alkaline ultrabasic massifs with carbonatites as final phases of magmatic system evolution; they form i ts central carbonatite core and are characterized by elevated Fe, Al and P concentrations. They also contain a complex of rare and rare-earth elements. Crust of laterite weathering of up to 400 m thick is present within the massifs. Phosphate, Nb, Y, Sc and TR content in crust of carbonatite weathering is much higher compared to unaltered rock differences. Their maximum values are in the sequence of specific sedimentary deposits f ormed a s denudation products of ore-bearing carbonatite crust precipitated in minor lake depressions and due to their intensive chemogenic transformation in hot humid climate. They are unique high-grade ores, with no world analogs in terms of mineral potential. Sometimes, these rocks are their natural concentrates averaging (in weight %) 7,21 Nb2O5, 0,578 Y2O3, 0,045 Sc2O3 and 10,16 TR2O3. The rocks composing the ore-bearing sequence show distinct evidence of sedimentary genesis: well-pronounced layered texture and facial zoning, presence of carbonized vegetable detrite and bacteriomorphic aggregates. Therefore, it is reasonable to regard a set of these formations as an independent stratigraphic unit, Tomtor sequence. Geological data suggest that it formed 340-280 Ma. Tomtor sequence can be an important prospecting criteria in prospecting for rare and rare-earth elements.
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Andrews, A. J., L. Owsiacki, R. Kerrich, and D. F. Strong. "The silver deposits at Cobalt and Gowganda, Ontario. I: Geology, petrography, and whole-rock geochemistry." Canadian Journal of Earth Sciences 23, no. 10 (October 1, 1986): 1480–506. http://dx.doi.org/10.1139/e86-143.
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The Ag–sulpharsenide vein deposits of northeastern Ontario occur along the north and northeastern margins of the Cobalt Embayment, a large irregular domain of Huronian-age clastic sediments intruded by Nipissing diabase sills and crosscut by regional-scale fault systems. The vein systems are mostly fault controlled, with mineralization always occurring adjacent to or within the diabase sills. Many of the mineralized structures crosscut the sills. All the economically productive deposits occur in close proximity to the Huronian–Archean unconformity where diabase sills and steeply dipping Archean volcanic sequences coincide.The vein systems show remarkable consistencies in their mineralogy, textures, and paragenesis. Their formation involved the precipitation of silicates (mainly quartz, chlorite, actinolite ± K-feldspar) during initial, limited dilation; this was followed by the introduction of significant quantities of carbonate (mainly calcite ± dolomite) during subsequent dilatant episodes. Most of the ore was precipitated during the silicate to carbonate transition. Wall-rock alteration haloes exhibit a silicate to carbonate paragenesis similar to that evident in the veins. Feldspathization is an important consequence of the alteration process, manifesting in the ubiquitous occurrence of albite in Nipissing diabase wall rocks and sporadic occurrences of K-feldspar in Archean basalt wall rocks.The mineralogy and chemistry of the veins and altered wall rocks indicate that CO2, Ca, Na, K, Ag, As, Co, Pb, rare earth elements, and in some cases Hg and Au were among the components introduced with the hydrothermal fluids. This was accompanied by significant net loss of Si, Fe, Mg, Zn, B, Li, and Sc from the wall rocks. The nature of the wall-rock alteration suggests that the mineralizing fluids were of high alkalinity and relatively low [Formula: see text]. They were not derived through lateral secretion but were introduced from a source remote from the immediate environment of ore deposition.Wall-rock alteration postdates the establishment of a low-temperature, regional alteration of the diabases and a chlorite spotting alteration in the Huronian sediments; the latter is a contact metamorphic effect accompanying diabase intrusion. These data indicate that Ag–sulpharsenide vein formation postdated intrusion of the diabases and much (possibly all) of their cooling histories.Collectively, our data discourage the theory that the Nipissing diabase sills acted purely as a heat and (or) fluid source in vein formation. A structural model is proposed in which the diabase sills acted as mechanically favourable sites for fracture generation during regional fault activity. This factor, together with the advent of boiling and (or) degassing of the mineralizing fluids at these specific sites are viewed as possible critical parameters mediating the localization and deposition of Ag–sulpharsenide ore. This model provides a reasonable explanation for the local and regional distribution of the deposits and appears to best satisfy all the geological, petrographic, and geochemical criteria.
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McNicoll, Vicki, Gerry Squires, Andrew Kerr, and Paul Moore. "The Duck Pond and Boundary Cu–Zn deposits, Newfoundland: new insights into the ages of host rocks and the timing of VHMS mineralization." Canadian Journal of Earth Sciences 47, no. 12 (December 2010): 1481–506. http://dx.doi.org/10.1139/e10-075.
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The Duck Pond Cu–Zn–Pb–Ag–Au deposit in Newfoundland is hosted by volcanic rocks of the Cambrian Tally Pond group in the Victoria Lake supergroup. In conjunction with the nearby Boundary deposit, it contains 4.1 million tonnes of ore at 3.3% Cu, 5.7% Zn, 0.9% Pb, 59 g/t Ag, and 0.9 g/t Au. The deposits are hosted by altered felsic flows, tuffs, and volcaniclastic sedimentary rocks, and the sulphide ores formed in part by pervasive replacement of unconsolidated host rocks. U–Pb geochronological studies confirm a long-suspected correlation between the Duck Pond and Boundary deposits, which appear to be structurally displaced portions of a much larger mineralizing system developed at 509 ± 3 Ma. Altered aphyric flows in the immediate footwall of the Duck Pond deposit contained no zircon for dating, but footwall stringer-style and disseminated mineralization affects rocks as old as 514 ± 3 Ma at greater depths below the ore sequence. Unaltered mafic to felsic volcanic rocks that occur structurally above the orebodies were dated at 514 ± 2 Ma, and hypabyssal intrusive rocks that cut these were dated at 512 ± 2 Ma. Some felsic samples contain inherited (xenocrystic) zircons with ages of ca. 563 Ma. In conjunction with Sm–Nd isotopic data, these results suggest that the Tally Pond group was developed upon older continental or thickened arc crust, rather than in the ensimatic (oceanic) setting suggested by previous studies.
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Souza Neto, J. A. "Geochemistry of the Ore Fluids in the Bonfim and Itajubatiba Gold Skarn Deposits, Northeastern Brazil: A PIXE Method Study." Mineralogical Magazine 62A, no. 3 (1998): 1432–33. http://dx.doi.org/10.1180/minmag.1998.62a.3.84.
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Zhai, Degao, Anthony E. Williams-Jones, Jiajun Liu, David Selby, Chao Li, Xiao-Wen Huang, Liang Qi, and Donghang Guo. "Evaluating the Use of the Molybdenite Re-Os Chronometer in Dating Gold Mineralization: Evidence from the Haigou Deposit, Northeastern China." Economic Geology 114, no. 5 (August 1, 2019): 897–915. http://dx.doi.org/10.5382/econgeo.2019.4667.
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Abstract The Haigou lode gold deposit (>40 tons [t] at 3.4 g/t), which is located near the eastern boundary of the Central Asian orogenic belt and the North China craton, is one of the largest gold deposits in northeastern China. Native gold is intergrown with molybdenite and pyrite in auriferous quartz veins hosted by a monzogranite-monzonite stock and locally by Proterozoic gneiss, thereby offering an excellent opportunity to directly date the mineralizing event. Uranium-Pb age determinations for zircon yielded ages for the monzogranite and monzonite of 327.1 ± 1.1 and 329.5 ± 1.0 Ma, respectively. Numerous mafic to felsic dikes, which are crosscut by ore veins (pre-ore), parallel to these veins (possibly synore), or crosscut by them (post-ore), were carefully examined and dated. Their zircon 206Pb/238U ages are 318.3 ± 1.0, 310.9 ± 1.1, and 134.9 ± 0.4 Ma, respectively, thereby placing the timing of gold mineralization within the relatively large interval of 318.3 ± 1.0 to 134.9 ± 0.4 Ma. The age of mineralization was determined directly using the Re-Os method applied to molybdenite. A total of 19 molybdenite samples separated from auriferous quartz veins yielded widely differing Re-Os model ages of 467 to 155 Ma, and replicate analyses of individual samples also yielded widely differing ages. Significantly, the wide range is attributable entirely to the results obtained for some coarse-grained molybdenite samples and is interpreted to be due to Re and Os isotope decoupling, the considerable spatial Re heterogeneity, the analytical procedure (e.g., use of small sample aliquots), and the post-ore deformation. Nine of the samples, which are all fine grained, yielded a robust weighted mean model age of 310 ± 3 Ma and an isochron age of 309 ± 8 Ma. Thus, the molybdenite Re-Os ages are identical, within uncertainty, to those of the dikes that are parallel to the ore veins, indicating that these dikes were emplaced contemporaneously with the ore and that they and the Haigou gold mineralization are of late Paleozoic age (ca. 310 Ma). Finally, a sericite sample obtained from an auriferous vein returned a 40Ar/39Ar plateau age of 165.3 ± 1.2 Ma, which is much younger than the age of the mineralization constrained by Re-Os age determinations of molybdenite. This indicates that the 40Ar/39Ar isotope system was reset by post-ore thermal events. Our new geochronological data provide evidence for late Paleozoic gold mineralization in Haigou, which makes it the oldest known lode gold deposit in the easternmost Central Asian orogenic belt, a finding that has important implications for precious metal mineral exploration in the eastern part of the Solonker-Xar Moron-Changchun-Yanji suture zone between the Central Asian orogenic belt and the North China craton. This study also indicates that accurate and reproducible molybdenite Re-Os ages representing the true timing of ore deposition need an integrated combination of careful petrography, proper sampling procedures, sufficiently large analyzed aliquots, multiple analyses of individual samples, and multiple dating methods.
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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.
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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.
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James, Eric W., and Christopher D. Henry. "Pb isotopes of ore deposits in Trans-Pecos Texas and northeastern Chihuahua, Mexico; basement, igneous, and sedimentary sources of metals." Economic Geology 88, no. 4 (July 1, 1993): 934–47. http://dx.doi.org/10.2113/gsecongeo.88.4.934.
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Figura, L. A., and M. S. Kovalchuk. "Ore-bearing of the osynova area of the Mezhyrichne deposit of titanium ores." Geochemistry and ore formation, no. 43 (2022): 59–73. http://dx.doi.org/10.15407/gof.2022.43.059.
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Information on the geological structure and ore bearing of the Osynova area of the Mezhyrich deposit of titanium ores, which is located in the northeastern part of the Volodar-Volyn massif of the Korosten pluton and is part of one of the most promising Volyn zirconium-titanium ore districts, is presented. It was found out that the ore-bearing potential of the Osynova area is determined by a spatially and paragenetically connected ore system, which is composed of titanium-bearing rocks of the crystalline basement of the Volodarsk-Volyn complex, their weathering crusts, continental (irshan suite, apt-albian) and marine (moshno-rudnyan suite, turon) by products of erosion and redeposition of eluvium. Based on the coordinates of the wells, their description, and test results, a target database was created, which became the basis for cartographic constructions. Maps of the relief of the top, bottom and the thickness of mesozoic-cennozoic eluvial kaolins were created; redeposited kaolins and apt-albian sands; sand-silica horizon of turon. It was found that in most cases there is a direct correlation between the relief of the bottom and the top of the ore-bearing deposits. As a rule, there is an inverse correlation between the thickness of deposits and the relief of their bottom and top. A set of maps was created showing the lateral distribution of average ilmenite contents in eluvial kaolins, continental and marine aptian-albian and turonian sediments. The lateral distribution of the average ilmenite contents in the sedimentary cover formations of different ages and genetics is uneven and characterized by significant contrasts (in eluvium — 0.4-57.2 kg/m3; in apt-albian sands — 1.0-162.58 kg/m3; in re-deposited apt-albian kaolins — 1.5-125.48 kg/m3; in sand-silica horizon of the turonian — 0.6-45.57 kg/m3). The best correlation exists between weathering crust formations and aptian-albian alluvial deposits. In the deposits lying above the geological section, the correlation with the eluvium is lost. The study of the distribution of the ilmenite content in the vertical cross-section of the wells showed that the ilmenite content in the sands is uneven with one or several levels of maximum enrichment. For example, in the vertical section of the sands (from bottom to top) there are layers with different contents (kg/m3) of ilmenite: 53.0-57.0; 27.0-37.0; 39.0-41.0; 10.0-23.0; 5.2-13.3; 27.0-68.2; 7.6-9.9; 49.0-56.0. On the other hand, in redeposited kaolins, the content of ilmenite in the vertical section is mostly uniform; sometimes one distinct level of maximal enrichment is present (rarely two such levels are present). For example, with a predominant ilmenite content of 27.0-32.0 kg/m3, in the lower and upper parts there are layers with a content of 48.0-63.0 kg/m3 and 42.0-68.0 kg/m3, and in the middle part of the formation, the content is 193.0-199.6 kg/m3.In Turonian sand-silica rocks, the maximum ilmenite content is located in the lower part of marine sediments.
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Syasko, A. A., N. N. Grib, V. S. Imaev, L. P. Imaeva, and I. I. Kolodeznikov. "Detailed airborne geophysical survey of complexly dislocated strata in the Sutam terrane (Aldan shield) during studies of iron-ore deposits." Geodynamics & Tectonophysics 11, no. 1 (March 19, 2020): 141–50. http://dx.doi.org/10.5800/gt-2020-11-1-0468.
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Magnetic exploration is the most informational and economical method of prospecting and exploration of iron-ore deposits. In rough-terrain and remote areas without any infrastructure, problems associated with ground-based methods can be avoided by using modern unmanned technologies that allow conducting geophysical surveys in a more efficient way. An unmanned aeromagnetic survey complex (aerial vehicle, UAV) Geoscan 401 was used to assess the possibility of using UAVs for aeromagnetic surveying of iron-ore deposits. Our experimental study was conducted in the well-studied area of the largest iron-ore deposit of South Yakutia. The UAV capacities were confirmed by comparing the aeromagnetic survey data with the available data obtained by ground magnetic exploration of the study area. By analysing magnetic fields, we established that the anomalies detected by the ground and aeromagnetic surveys were fully identical. Furthermore, a weak anomaly was discovered in the northeastern part of the study area (it was not reflected in the magnetic field from the ground survey data). Recalculation of the vertical gradient of the magnetic field shows that the anomaly is caused by a blind ore body. Its upper edge is located at a depth of 200–250 m from the day surface. In calculations for a data array without gradient intervals, a mean square error (MSE) amounts to 1.01 nT. An absolute error in the heights of the working and control flights did not exceed 1.5 m. Both the preliminary and control measurements were performed very efficiently. Profiles for UAV surveys were spaced by 100 m. A 1.0 km2 site was covered by one flight within approximately 20 minutes. The Geoskan-401 UAV is useful for obtaining orthophotos, topographic maps and 3D models of the surveyed territory as required for further studies consistent with the magnetic surveys. The aeromagnetic surveys were followed by trenching to verify the newly discovered anomalies. Based on the results of this experimental study, the forecast resources of the Sutam deposit should be increased by almost 250–350 million tons, i.e. plus 15 % to the previously explored and approved reserves of the Sutam field.
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Voisey, Christopher R., David Willis, Andrew G. Tomkins, Christopher J. L. Wilson, Steven Micklethwaite, Filomena Salvemini, Jeremy Bougoure, and William D. A. Rickard. "Aseismic Refinement of Orogenic Gold Systems." Economic Geology 115, no. 1 (January 1, 2020): 33–50. http://dx.doi.org/10.5382/econgeo.4692.
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Abstract Orogenic Au deposits have contributed the majority of Au recovered globally throughout history. However, the mechanism that concentrates Au to extremely high bonanza grades in small domains within these deposits remains enigmatic. The volume of fluid required to provide extreme Au endowments in localized occurrences is not reflected in field observations (e.g., in the extent of quartz veining or hydrothermal alteration). Detailed optical, scanning and transmission electron microscopy, nanoscale secondary ion mass spectrometry, and 3-D neutron tomography have been used to investigate the processes responsible for development of anomalously high grade ore (upward of 3% Au) found in quartz veins at Fosterville gold mine (Victoria, Australia). Distinct textural settings of visible Au include (1) Au concentrated along pressure solution seams associated with wall-rock selvages, (2) as nano- to microscale dusty Au seams parallel to pressure solution seams, and (3) in microscale tension fractures perpendicular to stylolitic seams. The distribution of Au in arsenopyrite and pyrite hosted within pressure solution seams changes as a function of the extent of deformation. Sulfides in highly deformed pressure solution seams exclusively host Au as nano- to micrometer-sized clusters within features associated with corrosion and brittle failure, whereas sulfides in mildly deformed pressure solution seams have Au bound in the crystal structure. It is proposed that Au supersaturation in fluids introduced during seismic periods led to the deposition of abundant Au nanoparticles in quartz-carbonate veins. Subsequent pressure dissolution of vein quartz and carbonate during interseismic intervals allowed for episodic increase in the Au/quartz ratio and permitted liberation and migration of Au nanoparticles, promoting Au grain growth in favorable textural settings. Galvanic corrosion and brittle fracturing of auriferous sulfides during the interseismic period allowed additional remobilization and/or enrichment of sulfide-hosted Au. Repetition of this mechanism over the time scale of deposit formation acted to concentrate Au within the lodes. This Au ore upgrading model, referred to as “aseismic refinement,” provides a new insight for the genesis of ultrarich Au mineralization and, based on textures reported from many Au deposits, may be a globally significant component in the formation of orogenic Au deposits.
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Phan, T. H., A. V. Petrov, M. Ph Do, M. G. Lai, and T. L. Nguyen. "Geological structure of central Vietnam by interpretation processing of gravitational survey data using the “COSCAD 3D” computer technology." Proceedings of higher educational establishments. Geology and Exploration 63, no. 5 (August 30, 2021): 77–90. http://dx.doi.org/10.32454/0016-7762-2020-63-5-77-90.
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Background. The central regions of Vietnam are of strategic importance for the Republic, being, in fact, the gateway to the ASEAN countries. Investing in the exploration and evaluation of mineral resources, in particular ore minerals hidden at great depths, is a specific and necessary task for the country.Aim. To clarify the structural-tectonic scheme of the analysed area and to identify the main fault systems and zoning of the Central Vietnam area by the gravitational field based on classification algorithms.Materials and methods. The objectives were achieved by assessing the total gradient of the gravitational field, analysing the distribution of the field variance and the results of tracing the axes of the gravitational field anomaly. Interpretation processing of gravity data was carried out using the “COSCAD 3D” computer technology of statistical and spectral correlation data analysis.Results. The defined fault systems, which play an important role in the processes of mineral formation, have a northwestern, northeastern and latitudinal strike. The zoning of the study area according to the gravitational field, its characteristics and available geological information made it possible to identify 13 homogeneous areas. Each area is characterised by a certain level of gravitational field, the values of dispersion and total field gradient, as well as correlations between attributes. The classification results confirms the complexity of the geological structure of the area under study and the presence of three main strikes of the systems of tectonic dislocations – northwestern, northeastern and latitudinal.Conclusions. A large number of tectonic dislocations of various strikes and intensities, revealed using the methods of the probabilistic-statistical approach, implemented in the “COSCAD 3D” computer technology, indicates that the area under study is promising in terms of ore deposits.
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Serebryakov, Evgenii, and Andrei Gladkov. "Geological and structural characteristics of deep-level rock mass of the Udachnaya pipe deposit." Записки Горного института 250 (September 29, 2021): 512–25. http://dx.doi.org/10.31897/pmi.2021.4.4.
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For hard rock massifs, structural disturbance is a key indicator of mining structure stability. The presence of intersecting structural elements in the massif reduces rock strength and leads to formation of potential collapse structures. In addition to that, disjunctive deformations that penetrate rock strata serve as channels for fluid migration and connect aquifers into a single system. It was established that the largest of them –faults of east-northeastern, northeastern and northwestern directions – form the kimberlite-bearing junction of the Udachnaya pipe. These faults represent zones of increased fracturing, brecciation and tectonic foliation, distinguished from adjacent areas by increased destruction of the rock mass. Specifics of tectonic fracture distribution within structural and lithological domains are determined by the presence of multidirectional prevailing systems of tectonic fracturing, as well as by differences in their quantitative characteristics. With some exceptions, the main systems form a diagonal network of fractures (northeastern – northwestern orientation), which is typical for larger structural forms – faults. Despite the differences in dip orientation of the systems, most of them correspond to identified directions, which is typical for both kimberlites and sedimentary strata. Overall disturbance of the massif, expressed in terms of elementary block volume, reaches its peak in the western ore body. For such type of deposits, friction properties of fracture structures have average values. Consideration of geological and structural data in the design and development of new levels of the deposit will allow to maintain the necessary balance between efficiency and safety of performed operations.
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Menez, J., and N. F. Botelho. "Ore characterization and textural relationships among gold, selenides, platinum-group minerals and uraninite at the granite-related Buraco do Ouro gold mine, Cavalcante, Central Brazil." Mineralogical Magazine 81, no. 3 (June 2017): 463–75. http://dx.doi.org/10.1180/minmag.2016.080.101.
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AbstractGold occurrences have been reported in the northeastern part of Goiás State since the beginning of the 18th Century. The main mineralization is associated with Paleoproterozoic peraluminous, syntectonic granites of the Aurumina Suite and associated metasedimentary,graphite-bearing country rocks of the Ticunzal Formation. In the Buraco do Ouro gold mine, the mineralization is hosted in muscovite-quartz mylonite in a silicified shear zone near the contact between biotite-muscovite granite and paragneiss of the Ticunzal Formation. The ore mineralogy consistsof gold, paraguanajuatite (Bi2Se3), kalungaite (PdAsSe), isomertieite [Pd11Sb2As2], mertieite II [Pd8(Sb,As)3], sperrylite (PtAs2), padmaite (PdBiSe), bohdanowiczite (AgBiSe2), clausthalite (PbSe),krutaite (CuSe2), ferroselite (FeSe2), uraninite (UO2) and unnamed Ag-Pb-Bi-Se minerals. Local magnetite concentrations and rare chalcopyrite and pyrite are also associated with both mineralized and barren mylonites in a gangue consisting of muscovite, quartzand rare tourmaline. High TiO2 muscovite clasts in the ore are interpreted as the magmatic muscovite of the original granite, and the mineralization is considered to be synchronous with the syntectonic granite intrusion during syn-emplacement shearing and alteration. The associationbetween granitic rocks and platinum-group element (PGE)-bearing gold mineralization observed in the Buraco do Ouro mine is uncommon and unique in the context of the Aurumina Suite and the Ticunzal Formation, where gold deposits and occurrences are gold-only. The chemical data suggest the possibilityof a solid solution between paraguanajuatite and bohdanowiczite. In addition, a complex intergrowth occurs between paraguanajuatite, clausthalite and Ag-Pb-Bi-Se phases, one of which, a Pb-Bi-Se phase could represent a new mineral. Uraninite is identified for the first time in this mineralassemblage and its concentration in the ore seems important, as revealed by high gamma spectrometric measurements in the samples collected in the mine. The association between gold and uranium constitutes a regional signature, observed in both gold and uranium deposits in the Cavalcante region.
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Ouyang, Hegen, Jingwen Mao, Ruizhong Hu, John Caulfield, and Zhenhua Zhou. "CONTROLS ON THE METAL ENDOWMENT OF PORPHYRY Mo DEPOSITS: INSIGHTS FROM THE LUMING PORPHYRY Mo DEPOSIT, NORTHEASTERN CHINA." Economic Geology 116, no. 7 (November 1, 2021): 1711–35. http://dx.doi.org/10.5382/econgeo.4850.
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Abstract Processes controlling the metal endowment of arc-related porphyry Mo deposits are not well understood. Located in northeastern China, the arc-related Luming porphyry Mo deposit has a proven reserve of 0.75 Mt Mo at an average grade of 0.092 wt % and is characterized by multiple pulses of alteration and mineralization. These features make this deposit an ideal location to investigate the role of multiple pulses of magmatism and fluid release in the evolution and formation of an arc-related porphyry Mo deposit. Molybdenum mineralization at Luming is typically observed as a series of molybdenite-bearing veins hosted within a composite intrusive complex, referred to as the Luming Intrusive Suite. Crosscutting relationships between intrusive units and offset veins indicate that the Luming Intrusive Suite is composed of five major, successive granitic intrusions: the premineralization plutonic biotite monzogranite and monzogranite units, and the synmineralization stock- and dike-like porphyritic monzogranite, granite porphyry, and syenogranite units. Each synmineralization unit is associated with similar vein sequences that comply with the general form of early EB-type biotite veins, through A-type quartz ± biotite and B-type quartz-molybdenite veins, to late D-type quartz-molybdenite ± pyrite ± chalcopyrite, molybdenite, quartz-pyrite ± calcite, and calcite ± clays veins. The intensity and volume of alteration and mineralization within a given synmineralization unit decrease from early- through inter- to late-mineralization units. Although minor Mo mineralization is associated with potassic alteration along B-type veins, the majority of the ore is associated with D-type quartz-molybdenite-pyrite and molybdenite veins rimmed by sericite-chlorite-pyrite alteration, which are primarily hosted in the two premineralization units. A combination of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb and hydrothermal biotite 40Ar/39Ar studies, together with available isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS) molybdenite Re-Os data, has resulted in a substantial reappraisal of the timing of magmatism and its association with molybdenite mineralization at Luming. The volumetrically dominant premineralization intrusive units have indistinguishable zircon U-Pb weighted mean 206Pb/238U ages ranging from 187.5 ± 2.8 to 186.5 ± 3.6 Ma (2σ), whereas the synmineralization units yield weighted mean 206Pb/238U ages from 178.6 ± 2.2 to 175.6 ± 3.0 Ma (2σ). The zircon U-Pb weighted mean 206Pb/238U ages of the synmineralization units are indistinguishable from the mean molybdenite Re-Os model (178.1 ± 2.7; 2σ) and hydrothermal biotite 40Ar/39Ar plateau (174.7 ± 1.1 Ma; 2σ) ages within uncertainty, confirming a genetic link with mineralization. Melt inclusion data show that the synmineralization intrusions were Mo poor, with Mo concentrations <4 ppm. The data presented here suggest that molybdenite mineralization at Luming was most likely accomplished through three discrete magmatic-hydrothermal events during assembly of the Mo-poor synmineralization intrusive complex. The giant Luming deposit appears to be related to multiple pulses of magmatic-hydrothermal activities, resulting in the superposition of temporally distinct mineralization events. Our results suggest that pulsed release of ore-forming magmas and fluids, which are channeled along focusing structures like small porphyry fingers within a focused area, from a large magma chamber at depth may play a major role in the formation of large to giant porphyry Mo deposits of both the arc-related and Climax types. This conclusion is in line with field observations of a number of large to giant porphyry Mo deposits, which commonly show reversals in magmatic-hydrothermal evolutionary trend and are associated with multiple pulses of small stocks and dikes that are separate in time and space.
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Luong, Khang Quang, Hung The Khuong, Dung Tien Vo, and Tuyen Danh Nguyen. "Mineralogical and geological characteristics of the Nui Phao tungsten deposit and its resource in the Dai Tu area, northeastern Vietnam." Journal of Mining and Earth Sciences 63, no. 6 (December 31, 2022): 1–11. http://dx.doi.org/10.46326/jmes.2022.63(6).01.
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Typically, granitic intrusions that document the lengthy and intricate history of the magmatic-hydrothermal system are linked to tungsten deposits. Uncertainty persists about the genetic relationship between tungsten mineralization and magmatic-hydrothermal development. The primary tungsten deposit in the Dai Tu region, known as the Nui Phao deposit, has been the subject of a petrographical and microscopic examination. Tungsten mineralization in the Dai Tu area often occurs in association with the formation of skarn and greisen bodies, and it has drawn much attention from geoscientists. Based on microscopic observations, tungsten ores can be divided into three mineralization stages, namely skarnisation, greisenization, and hydrothermal stage. To examine the geochemical features of the tungsten ores, the SEM-EDS and Microscope analytical methods were performed in this study. Research results indicate that the Nui Phao tungsten deposit was formed due to different tectonic and magmatism episodes. Accordingly, the Nui Phao tungsten deposit is relatively complicated with the multi-sources of ore components. Most of the tungsten ore was accumulated in association with the metasomatism between the Ordovician-Silurian carbonate-terrigenous sedimentary rocks of the Phu Ngu formation and the Cretaceous two-mica granite of the Pia Oac complex. The research results indicate that tungsten resources obtained at levels 122 and 333 are about 227.6 thousand tons. Moreover, the hydrothermal alteration and metasomatism in the study area are influenced by at least three metasomatic episodes, including skarnisation, greisenisation, and the late hydrothermal alteration of medium to a low temperature that is genetically related to fluorite-polymetallic mineralization.