Researches in Earth Sciences

Researches in Earth Sciences

Geology, alteration, mineralization, and fluid inclusions of the Majidabad iron deposit, Ardabil province

Document Type : Original Article

Authors
1 Department of Mining Engineering, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
2 Department of Geology, Faculty of Basic Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
Abstract
Introduction
The Majidabad area is located approximately 20 km southwest of Nir city, Ardabil Province, northwestern of Iran. Based on the division of sedimentary-structural zones of Iran (Nabavi, 1976), this area is considered a part of the Alborz-Azarbaidjan zone. In Azarbaidjan, deposits of lead, zinc, iron, copper, and molybdenum are known to be among the most important ore minerals. The metallogenic zones of Takab, Ahar-Arasbaran, and Tarom-Hashtjin can be identified in Azarbaidjan. The Majidabad area is located in eastern part of Azarbaidjan. Among the research works carried out in the Majidabad area, one can mention the exploration operations such as geological, geophysical and geochemical studies by the Industry, Mining, and Trade Organization of Ardabil Province (IMTOAP, 2012). Based on these studies, the highest and lowest amounts of iron oxide (magnetite) in this area were determined to be about 93.29 and 27.3%, respectively, with an approximate average of 54.47%. However, no detailed and scientific study has been conducted so far regarding the characteristics of alteration and mineralization zones and the characteristics of hydrothermal fluids in this area. In this study, an attempt is made to investigate the geological, alteration, mineralization, and fluid inclusions characteristics in the Majidabad area. This research also attempts to discuss the physiochemical properties and conditions governing the ore-forming fluid using the results of fluid inclusions studies. The results of this research can play an effective role in the exploration and identification of ore-bearing zones in other similar areas in the country.
Materials and Methods
This research was conducted in two stages: field and laboratory studies. In the field stage, a field visit to the area was first conducted to identify rock units, alteration and mineralization zones, and the relationship of ore-bearing veins to host rocks. Then, 75 samples were taken from rock units and alteration and mineralization zones. In the laboratory stage, 10 thin-section samples and 20 thin-polished sections were prepared and studied. Microthermometry studies of fluid media were conducted at Tarbiat Modares University, Tehran, using a Linkam model THMSG600 device mounted on a ZEISS microscope. This device has the ability to change temperatures from +600 to -200°C. Calibration of the device was performed during the heating stage (with an accuracy of 0.6°C) using a cesium nitrate standard with a melting point of +414°C and during the cooling stage (with an accuracy of 0.2°C) using an n-hexane standard with a melting point of -94.3°C.
Results and Discussion
Based on its geological location, the Majidabad area is located on the 1:100000 Sarab geological map (Behrouzi and Amini Azar, 1992). The oldest exposed unit in this area is related to Eocene volcanic and pyroclastic rocks, including tuff, volcanic breccias, and andesitic and rhyolitic tuffs along with basaltic lavas and basaltic andesite, which are covered by the Oligocene marl and conglomerate unit and then by Miocene andesitic eruptions (in the form of tuff and lava). All of these volcanic-pyroclastic complexes are cut by post-Miocene subvolcanic bodies, dykes, and diorite stocks. Based on field and microscopic studies conducted in the Majidabad area, types of silicic, sericitic, argillic, and propylitic alterations have developed in this area. These alterations have mostly affected Eocene rock units. According to field studies conducted in the Majidabad area, mineralization in this area has occurred mainly in the form of magnetite veins. Magnetite veins are often hosted by Eocene tuff units and their thickness usually varies from a few centimeters to several meters. These veins are mostly in the form of masses and mainly have a north-south trend. Based on field and microscopic studies conducted in the Majidabad area, mineralization in this area occurred in two stages: hypogene and supergene. During the hypogene stage, as a result of the activity of hydrothermal fluids, magnetite veins and veinlets were formed in the area, and various types of hydrothermal alterations (silicic, sericitic, argillic, and propylitic) developed around the ore-bearing veins. Ore minerals such as magnetite, pyrite, and chalcopyrite formed during this stage of mineralization within the ore-bearing veins. During the supergene stage, the reaction of descending surface fluids with primary minerals (magnetite, pyrite, and chalcopyrite) in the area has caused the formation of secondary minerals, including iron oxides and hydroxides (goethite, hematite, and jarosite) and secondary copper sulfides (bornite, chalcocite, covellite, and digenite). According to field and microscopic studies, the most important gangue mineral in this area is calcite. On the basis of content of the main phases and the classifications provided (Shepherd et al., 1985), types of mono-phase vapor (V), liquid-rich two-phase (LV) and vapor-rich two-phase (VL) fluid inclusions were identified in the investigated inclusions. The melting temperature of the first piece of ice in the fluid inclusions of the study area was obtained in the range of -26 to -28 °C. These melting temperatures of the first ice fragments indicate that the ore-forming fluid of the Majidabad area contained amounts of KCl and MgCl2 in addition to NaCl (Goldstein, 2003; Prokofiev et al, 2010). The melting temperature of the last ice pieces (Tmice) in the fluid inclusions was measured in the temperature range between -1.2 and -4.8 °C. According to the equation proposed by Bodnar (2003) and according to the melting temperature of the last ice pieces (Tmice), the salinity values ​​of the fluid inclusions of the Majidabad area were determined to be in the range of 2.07 to 7.59 wt% NaCl eq; however, the highest frequency is related to the range of 2 to 3 wt% NaCl eq. The homogenization temperatures of fluid inclusions in the study area vary in the temperature range between 123 and 235 °C; however, the highest frequency belongs to the temperature range between 120 and 140 °C. The coexistence of mono-phase vapor, liquid-rich two-phase, and vapor-rich two-phase fluid inclusions in samples from the Majidabad area indicates the occurrence of ore-forming fluid boiling in this area (Albinson et al, 2001; Moncada et al, 2017; Simmons et al, 2005). In addition, the presence of plumose and comb textures in ore-bearing veins and veinlets may indicate the occurrence of boiling of the ore-forming fluid in the study area during mineralization (Hedenquist et al, 2000; Moncada et al, 2012). Therefore, considering the occurrence of ore-forming fluid boiling in the area, the homogenization temperatures of fluid inclusions do not require pressure correction (Simeone and Simmons, 1999); because in this case, the ore-forming fluid was most likely experiencing hydrostatic pressure at the time of trapping. Therefore, the homogenization temperature of fluid inclusions can be approximately equivalent to their entrapment temperature (Roedder and Bodnar, 1980; Simmons et al, 2005; Simeone and Simmons, 1999). Hydrostatic pressure values ​​for the hydrothermal fluid of the Majidabad area were estimated to be less than 50 bar. These hydrostatic pressure values ​​can be equivalent to depths of less than 500 meters below the water table. To determine the depth of mineralization in the study area, the homogenization temperature versus depth diagram (Haas, 1971) was also used. Considering the highest homogenization temperature (235 °C) and highest salinity (7.59 wt% NaCl eq) of the fluid inclusions, the approximate depth of mineralization in this area was determined to be about 300 m. To determine the evolutionary trends of the ore-forming fluid in the Majidabad area, the salinity versus homogenization diagram of fluid inclusions (Shepherd et al, 1985; Wilkinson, 2001) was used. According to this diagram, the fluid inclusions of the study area indicate two evolutionary processes of
boiling and dilution by surface waters, as the most important mechanisms for the deposition of ore metals in the study area. The density of the fluid inclusions in the study area can be determined using the homogenization temperature versus salinity diagram (Wilkinson, 2001) without considering their trapping conditions. According to this diagram, the density of ore-forming fluids in the Majidabad area mainly varies between 0.88 and 0.97 g/cm3. The salinity versus homogenization temperature diagram (Pirajno, 2009) was used to determine the type of effective complexes in transporting ore metals in the study area. According to this diagram, sulfide complexes have played an important role in transporting ore metals in the Majidabad area.
Conclusion
The most important rock units in the Majidabad area include Eocene to Oligocene volcanic-pyroclastic rocks, which are cut by post-Miocene diorite bodies. The most important alterations in this area are silicic, sericitic, argillic, and propylitic alterations. Mineralization in this area has often occurred in the form of magnetite veins hosted by Eocene pyroclastic units. Mineralization in this area has occurred in two stages: hypogene and supergene. In the hypogene stage, the primary minerals magnetite, pyrite, and chalcopyrite are formed. Secondary minerals such as iron oxides and hydroxides (goethite, hematite, and jarosite) and secondary copper sulfides (bornite, chalcocite, covellite, and digenite) were formed during the supergene stage. Calcite is the most important gangue mineral in this area. The salinity values ​​of fluid inclusions in the Majidabad area vary between 2.07 and 7.59 wt% NaCl eq. The homogenization temperatures of the fluid inclusions in the study area were measured in the temperature range between 123 and 235 °C. The approximate depth of mineralization in this area was determined to be about 300 m. Boiling and dilution processes by surface waters are the most important mechanisms for the deposition of ore metals in the study area. The density of ore-forming fluids in the Majidabad area mostly varies between 0.88 and 0.97 g/cm3. Sulfide complexes have played an effective role in transporting ore metals in the Majidabad area. Considering the geological, alteration, mineralization, mineralogy, and texture characteristics, as well as the characteristics of the ore-forming fluid in the Majidabad area, mineralization in this area can be considered hydrothermal (vein).
Keywords
Subjects

Adeli, Z., Rassa, I. and Darvishzadeh, A., 2014. Geochemistry and origin of Haftcheshmeh Cu-porphyry deposit magma, East-Azerbaijan, Iran. Scientific Quarterly Journal of Geosciences, v. 23(90), p. 197-208 (In Persian) https://doi.org/10.22071/gsj.2014.43996
Aghaei, M., Rastad, E., Shamanian, G.H. and Madanipour, S., 2023. Characteristics of the gold-bearing and barren quartz veins at the Zaylik-Sarilar epithermal deposit, Ahar-Arasbaran zone, NW Iran: Evidence from mineralogy, alteration, texture and fluid inclusion. Ore Geology Reviews, v. 154, 105341. https://doi.org/10.1016/j.oregeorev.2023.105341
Aghazadeh, M., Hou, Z., Badrzadeh, Z. and Zhou, L., 2015. Temporal-spatial distribution and tectonic setting of porphyry copper deposits in Iran: constraints from zircon U-Pb and molybdenite Re-Os geochronology. Ore geology reviews, v. 70, p. 385-406. https://doi.org/10.1016/j.oregeorev.2015.03.003
Albinson, T., Norman, D.I., Cole, D. and Chomiak, B., 2001. Controls on formation of low-sulfidation epithermal deposits in Mexico: Constraints from fluid inclusion and stable isotope data. In: Albinson, T., Nelson, C.E. (Eds.), New Mines and Discoveries in Mexico and Central America. Society of Economic Geologists, Littleton, p. 1-32. https://doi.org/10.5382/SP.08.01
Asadi, H.H., Voncken, J.H.L., Kühnel, R.A. and Hale, M., 2000. Petrography, mineralogy and geochemistry of the Zarshuran Carlin-like gold deposit, northwest Iran. Mineralium Deposita, v. 35(7), p. 656-671. https://doi.org/10.1007/s001260050269
Atalou, S., Nazafati, N., Lotfi, M. and Aghazadeh, M., 2017. Fluid inclusion investigations of the Masjed Daghi copper-gold porphyry-epithermal mineralization, East Azerbaijan Province, NW Iran. Open Journal of Geology, v. 7(8), p. 1110-1127. https://doi.org/10.4236/ojg.2017.78074
Behrouzi, A. and Amini Azar, R., 1992. Geological map of Sarab, scale 1:100000. Geological Survey and Mineral Exploration of Iran (In Persian).
Bodnar, R.J., 2003. Introduction to aqueous-electrolyte fluid inclusions. In: Samson, I., Anderson, A., Marshal, D. (Eds.), Fluid inclusions: Analysis and interpretation. Mineralogical Association of Canada, Vancouver, p. 81-100. https://doi.org/10.3749/9780921294672.ch04
Boni, M., Gilg, H.A., Balassone, G., Schneider, J., Allen, C.R. and Moore, F., 2007. Hypogene Zn carbonate ores in the Angouran deposit, NW Iran. Mineralium Deposita, v. 42, p. 799-820. https://doi.org/10.1007/s00126-007-0144-4
Calagari, A.A., 2004. Fluid inclusion studies in quartz veinlets in the porphyry copper deposit at Sungun, East Azarbaidjan, and Iran. Journal of Asian Earth Sciences, v. 23(2), p. 179-189. https://doi.org/10.1016/S1367-9120(03)00085-3
Calagari, A.A. and Hosseinzadeh, M.R., 2006. The mineralogy of copper-bearing skarn to the east of the Sungun-Chay River, East-Azarbaidjan, Iran. Journal of Asian Earth Sciences, v. 28(4-6), p. 423-438. https://doi.org/10.1016/j.jseaes.2005.11.009
Daliran, F., 2008. The carbonate rock-hosted epithermal gold deposit of Agdarreh, Takab geothermal field, NW Iran, hydrothermal alteration and mineralisation. Mineralium Deposita, v. 43, p. 383-404. https://doi.org/10.1007/s00126-007-0167-x
Daliran, F., Pride, K., Walther, J., Berner, Z.A. and Bakker, R.J., 2013. The Angouran Zn (Pb) deposit, NW Iran: evidence for a two stage, hypogene zinc sulfide-zinc carbonate mineralization. Ore Geology Reviews, v. 53, p. 373-402. https://doi.org/10.1016/j.oregeorev.2013.02.002
Ebrahimi, S., Pan, Y., Alirezaei, S. and Mehrpartou, M., 2009. Fluid inclusion and mineralogical studies of the Sharafabad epithermal gold deposit, NW Iran. Scientific Quarterly Journal of Geosciences, v. 18(71), p. 149-154 (In Persian). https://doi.org/10.22071/gsj.2010.57004
Ebrahimi, S., Alirezaei, S., Pan, Y. and Mohammadi, B., 2017. Geology, mineralogy and ore fluid characteristics of the Masjed Daghi gold bearing veins system, NW Iran. Journal of Economic Geology, v. 9(2), p. 561-586 (In Persian). https://doi.org/10.22067/econg.v9i2.51493
Ebrahimi, S., Pan, Y. and Rezaeian, M., 2021. Origin and evolution of the Masjed Daghi Cu-Au-Mo porphyry and gold epithermal vein system, NW Iran: constraints from fluid inclusions and sulfur isotope studies. Mineralogy and Petrology, v. 115, p. 643-662. https://doi.org/10.1007/s00710-021-00761-z
Ferdowsi, R., Calagari, A.A., Simmonds, V. and Miranvari, A., 2021. Evolution of the gold (copper) mineralization in the porphyry stock and the related skarn zones and epithermal veins in the Astarghan area, NW Iran: Evidence from fluid inclusion, mineral chemistry and sulfur isotope analyses. Ore Geology Reviews, v. 136, 104196. https://doi.org/10.1016/j.oregeorev.2021.104196
Gharesi, M., Rassa, I. and Yazdi, M., 2018. Investigation of Mazraeh Skarn mineralization, North of Ahar, with an emphasis on fluid inclusion studies. Iranian Journal of Crystallography and Mineralogy, v. 26(1), p. 229-244. (In Persian) https://doi.org/10.29252/ijcm.26.1.229
Ghasemi Siani, M., Mehrabi, B., Nazarian, M., Lotfi, M. and Corfu, F., 2022. Geology and genesis of the Chomalu polymetallic deposit, NW Iran. Ore Geology Reviews, v. 143, 104763. https://doi.org/10.1016/j.oregeorev.2022.104763
Goldstein, R.H., 2003. Petrographic analysis of fluid inclusions. In: Samson, I., Anderson, A., Marshall, D. (Eds.), Fluid Inclusions: Analysis and Interpretation. Mineral Associated of Canada, Vancouver, p. 9-53. https://doi.org/10.3749/9780921294672.ch02
Haas, J.L., 1971. The effect of salinity on the maximum thermal gradient of a hydrothermal system at hydrostatic pressure. Economic Geology, v. 66(6), p. 940-946. https://doi.org/10.2113/gsecongeo.66.6.940
Hedenquist, J.W., Arribas, A.R. and Gonzalez-Urien, E., 2000. Exploration for epithermal gold deposits. In: Hagemann, S.G., Brown, P.E. (Eds.), Gold in 2000. Society of Economic Geologists, Littleton, p. 245-277. https://doi.org/10.5382/Rev.13.07
Heidari, S.M., Daliran, F., Paquette, J.L. and Gasquet, D., 2015. Geology, timing, and genesis of the high sulfidation Au (-Cu) deposit of Touzlar, NW Iran. Ore Geology Reviews, v. 65, p. 460-486. https://doi.org/10.1016/j.oregeorev.2014.05.013
Hosseinzadeh, M.R., Calagari, A.A., Moayyed, M., Hadj-Alilu, B. and Moazzen, M., 2010. Study of hypogen alteration and copper mineralization in Sonajil area (east of Herris, East Azarbaidjan). Scientific Quarterly Journal of Geosciences, v. 19(74), p. 3-12 (In Persian). https://doi.org/10.22071/gsj.2010.57312
IMTOAP, 2012. Final report on the exploration of Soganlou magnetite iron ore. Industry, Mining, and Trade Organization of Ardabil Province, Iran, 145 p. (In Persian).
Jamali, H. and Mehrabi, B., 2015. Relationships between arc maturity and Cu-Mo-Au porphyry and related epithermal mineralization at the Cenozoic Arasbaran magmatic belt. Ore Geology Reviews, v. 65(2), p. 487-501. https://doi.org/10.1016/j.oregeorev.2014.06.017
Jamali, H., Dilek, Y., Daliran, F., Yaghubpur, A. and Mehrabi, B., 2010. Metallogeny and tectonic evolution of the Cenozoic Ahar-Arasbaran volcanic belt, northern Iran. International Geology Review, v. 52(4-6), p. 608-630. https://doi.org/10.1080/00206810903416323
Kouhestani, H., Azimzadeh, A.M., Mokhtari, M.A.A. and Ebrahimi, M. 2017. Mineralization and fluid evolution of epithermal base metal veins from the Aqkand deposit, NW Iran. Neues Jahrbuch für Mineralogie-Abhandlungen, v. 194(2), p. 139-155. https://doi.org/10.1127/njma/2017/0036
Kouhestani, H., Mokhtari, M.A.A., Qin, K.Z. and Zhao, J.X., 2019a. Fluid inclusion and stable isotope constraints on ore Genesis of the Zajkan epithermal base metal deposit, Tarom-Hashtjin metallogenic belt, NW Iran. Ore Geology Reviews, v. 109, p. 564-584. https://doi.org/10.1016/j.oregeorev.2019.05.014
Kouhestani, H., Mokhtari, M.A.A., Qin, K.Z. and Zhao, J.X., 2019b. Origin and evolution of hydrothermal fluids in the Marshoun epithermal Pb-Zn-Cu (Ag) deposit, Tarom-Hashtjin metallogenic belt, NW Iran. Ore Geology Reviews, v. 113, 103087. https://doi.org/10.1016/j.oregeorev.2019.103087
Kouhestani, H., Mokhtari, M.A.A., Qin, K.Z. and Zhang, X.N., 2020. Genesis of the Abbasabad epithermal base metal deposit, NW Iran: Evidences from ore geology, fluid inclusion and O-S isotopes. Ore Geology Reviews, v. 126, 103752. https://doi.org/10.1016/j.oregeorev.2020.103752
Lotfi, M. and Karimi, M., 2004. Mineralogy and ore genesis of Bayche - Bagh five elemen (Ag-Ni-Co-As-Bi) vein deposit (NW Zanjan, Iran). Scientific Quarterly Journal of Geosciences, v. 14(53), p. 40-55 (In Persian).
Mehrabi, B., Ghasemi Siani, M., Goldfarb, R., Azizi, H., Ganerod, M. and Marsh, E.E., 2016. Mineral assemblages, fluid evolution and Genesis of polymetallic epithermal veins, Gulojeh district, NW Iran. Ore Geology Reviews, v. 78, p. 41-57. https://doi.org/10.1016/j.oregeorev.2016.03.016
Mohammadi Niaei, R.M., Daliran, F., Nezafati, N., Ghorbani, M., Zakariaei, J.S. and Kouhestani, H., 2015. The Ay Qalasi deposit: an epithermal Pb-Zn (Ag) mineralization in the Urumieh-Dokhtar volcanic belt of northwestern Iran. Neues Jahrbuch für Mineralogie Abhandlungen, v. 192, p. 263-274. https://doi.org/10.1127/njma/2015/0284
Moncada, D., Mutchler, S., Nieto, A., Reynolds, T.J., Rimstidt, J.D. and Bodnar, R.J., 2012. Mineral textures and fluid inclusion petrography of the epithermal Ag-Au deposits at Guanajuato, Mexico: application to exploration. Journal of Geochemical Exploration, v. 114, p. 20-35. https://doi.org/10.1016/j.gexplo.2011.12.001
Moncada, D., Baker, D. and Bodnar, R.J., 2017. Mineralogical, petrographic and fluid inclusion evidence for the link between boiling and epithermal Ag-Au mineralization in the La Luz area, Guanajuato Mining District, Mexico. Ore Geology Reviews, v. 89, p. 143-170. https://doi.org/10.1016/j.oregeorev.2017.05.024
Nabavi, M., 1976. An Introduction to the Geology of Iran. Geological Survey of Iran Publication, Tehran, 109 p. (In Persian).
Najafzadeh, M., Ebrahimi, M., Mokhtari, M.A.A. and Kouhestani, H., 2016. The Arabshah occurrence: an epithermal Au-As-Sb carlin type mineralization in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, Western Azerbaijan. Advanced Applied Geology, v. 6(4), p. 62-77 (In Persian). https://doi.org/10.22055/aag.2016.12709
Pirajno, F., 2009. Hydrothermal processes and mineral systems. Springer, Berlin, 1250 p.
Prokofiev, V.Y., Garofalo, P.S., Bortnikov, N.S., Kovalenker, V.A., Zorina, L.D., Grichuk, D.V. and Selektor, S.L., 2010. Fluid inclusion constraints on the genesis of gold in the Darasun district (eastern Transbaikalia). Russia, Economic Geology, v. 105(2), p. 395-416. https://doi.org/10.2113/gsecongeo.105.2.395
Rezazadeh, S., Hosseinzadeh, M.R., Raith, J.G. and Moayyed, M., 2020. Mineral chemistry and phase relations of Co-Ni arsenides and sulfarsenides from the Baycheh-Bagh deposit, Zanjan province, Iran. Ore geology reviews, v. 127, 103836. https://doi.org/10.1016/j.oregeorev.2020.103836
Roedder, E., 1984. Fluid inclusions. Mineralogical Society of America, Virginia, 644 p.
Roedder, E. and Bodnar, R.J., 1980. Geologic pressure determinations from fluid inclusion studies. Annual Review of Earth and Planetary Sciences, v. 8, p. 263-301. https://doi.org/10.1146/annurev.ea.08.050180.001403
Shahbazi, S., Ghaderi, M. and Alfonso, P., 2019. Mineralogy, alteration, and sulfur isotope geochemistry of the Zehabad intermediate-sulfidation epithermal deposit, NW Iran. Turkish journal of earth sciences, v. 28, p. 882-901. https://doi.org/10.3906/yer-1902-1
Shepherd, T.J., Ranbin, A.H. and Alderton, D.H.M., 1985. A practical guide to fluid inclusion studies. Blackie, Glasgow, 223 p.
Simeone, R. and Simmons, S.F., 1999. Mineralogical and fluid inclusion studies of low sulfidation epithermal veins at Osilo (Sardinia), Italy. Mineralium Deposita, v. 34(7), p. 705-717. https://doi.org/10.1007/s001260050229
Simmons, S.F., White, N.C. and John, D.A., 2005. Geological characteristics of epithermal precious and base metal deposits. In: Hedenquist, J.W., Thompson, J.F.H., Goldfarb, J.R., Richards, J.P. (Eds.), One Hundredth Anniversary Volume. Society of Economic Geologists, Littleton, p. 485-522. https://doi.org/10.5382/AV100.16
Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American mineralogist, v. 95(1), p. 185-187. https://doi.org/10.2138/am.2010.3371
Wilkinson, J.J., 2001. Fluid inclusions in hydrothermal ore deposits. Lithos, v. 55(1-4), p. 229-272. https://doi.org/10.1016/S0024-4937(00)00047-5
Zamanian, H., Rahmani, S. and Zareisahameih, R., 2019. Fluid inclusion and stable isotope study of the Lubin-Zardeh epithermal Cu-Au deposit in Zanjan Province, NW Iran: Implications for ore genesis. Ore Geology Reviews, v. 112, 103014. https://doi.org/10.1016/j.oregeorev.2019.103014