Ore Potential Research Articles

Petrology and geochemistry of Permian mafic–ultramafic intrusions in the Emeishan large igneous province, SW China: Insight into the ore potential

Mafic–ultramafic layered intrusions constitute important components in the western part of the Emeishan large igneous province (LIP) in SW China. Here we present zircon U–Pb geochronology, geochemistry and Sr–Nd isotopic data from four representative barren mafic–ultramafic intrusions in Wupodan (WPD), Shangyi (SY), Louyi (LY) and Xiayi (XY). All these four intrusions were emplaced during the Late Permian, coeval with the formation of Emeishan flood basalts and associated mineralized intrusions. All rocks from the four intrusions exhibit mineralogical homogeneity, in the absence of any associated intermediate-felsic plutons. Chondrite-normalized REE patterns of LY, SY and WPD intrusions exhibit moderately fractionated patterns with (La/Yb)N of 3.55–5.12, whereas the XY intrusion shows pronounced LREE enrichment with (La/Yb)N of 11.61–12.94. Samples from the four intrusions lack any significant Eu anomalies, and have low εNd(t) values of −3.0 to −1.9 and variable initial 87Sr/86Sr ratios of 0.7057–0.7074, overlapping with the field defined by Permian Emeishan basalts and the related mineralized mafic–ultramafic intrusions. Clinopyroxenes from the SY, WPD and LY intrusions show relatively high equilibrium temperatures ranging from ~1300°C to ~1400°C, which can be regarded as a signature of plume-related origin. Although the clinopyroxenes from the XY intrusion exhibit a relatively lower equilibrium temperature (~1200°C), the geochemical signature resembling OIB suggests a plume-related origin. Thus, these intrusions appear to be part of the Emeishan LIP. These features, combined with moderate to pronounced depletion of HFSE (e.g. Nb, Ta and Ti) and enrichment of LILE (e.g. Rb, Ba, K), correlate the LY, SY and WPD intrusions to the interaction between mantle plume and subcontinental lithospheric mantle that had been previously modified by subduction-related materials. In contrast, the XY intrusion was derived from the plume source contaminated by subcontinental lithospheric mantle. We also attempt a comparison between the unmineralized and mineralized intrusions in terms of their parental magmas, crystallization history, nature of the mantle source, degrees of partial melting of source and the extent of crustal contamination. Some geochemical criteria that may be useful in discriminating between mineralized and unmineralized mafic–ultramafic intrusions are summarized, and insights into the ore potential of the four barren intrusions are addressed.

How Mineralogy and Geochemistry Can Improve the Significance of Pb Isotopes in Metal Provenance Studies

Lead isotopes combined with trace element data represent a powerful tool for non‐ferrous metal provenance studies. Nevertheless, unconsidered geological factors and archaeological data, as well as ignored analytical procedures, may substantially modify the interpretation of the isotopic and trace element signature obtained as a potential ore candidate. Three archaeological examples, accompanied by high‐resolution lead isotopic measurements (MC–ICP–MS), are presented here to discuss the above‐mentioned criticisms and to propose some solutions. The first example deals with prehistoric/historical gold/silver‐mining activity from Romania (the Baia Borşa and Roşia Montană ore deposits). The second one regards the lead/silver metallurgical activity from the Mont‐Lozère massif (France) during medieval times. The third example focuses on the comparison between two batches of lead isotope data gathered on Roman lead ingots from Saintes‐Maries‐de‐la‐Mer, using different SRM 981 Pb values.

Genesis of massive sulfide deposits in the Verkhneural’sk ore district, the South Urals, Russia: Evidence for magmatic contribution of metals and fluids

Melt inclusions and aqueous fluid inclusions in quartz phenocrysts from host felsic volcanics, as well as fluid inclusions in minerals of ores and wall rocks were studied at the Cu-Zn massive sulfide deposits in the Verkhneural’sk ore district, the South Urals. The high-temperature (850–1210°C) magmatic melts of volcanic rocks are normal in alkalinity and correspond to rhyolites of the tholeiitic series. The groups of predominant K-Na-type (K2O/Na2O = 0.3–1.0), less abundant Na-type (K2O/Na2O = 0.15–0.3), and K-type (K2O/Na2O = 1.9–9.3) rhyolites are distinguished. The average concentrations (wt %) of volatile components in the melts are as follows: 2.9 H2O (up to 6.5), 0.13 Cl (up to 0.28), and 0.09 F (up to 0.42). When quartz was crystallizing, the melt was heterogeneous, contained magnetite crystals and sulfide globules (pyrrhotite, pentlandite, chalcopyrite, bornite). High-density aqueous fluid inclusions, which were identified for the first time in quartz phenocrysts from felsic volcanics of the South Urals, provide evidence for real participation of magmatic water in hydrothermal ore formation. The fluids were homogenized at 124–245°C in the liquid phase; the salinity of the aqueous solution is 1.2–6.2 wt % NaCl equiv. The calculated fluid pressure is very high: 7.0–8.7 kbar at 850°C and 5.1–6.8 kbar at 700°C. The LA-ICP-MS analysis of melt and aqueous fluid inclusions in quartz phenocrysts shows a high saturation of primary magmatic fluid and melt with metals. This indicates ore potential of island-arc volcanic complexes spatially associated with massive sulfide deposits. The systematic study of fluid inclusions in minerals of ores and wall rocks at five massive sulfide deposits of the Verkhneural’sk district furnished evidence that ore-forming fluids had temperature of 375–115°C, pressure up to 1.0–0.5 kbar, chloride composition, and salinity of 0.8–11.2 (occasionally up to 22.8) wt % NaCl equiv. The H and O isotopic compositions of sericite from host metasomatic rocks suggest a substantial contribution of seawater to the composition of mineral-forming fluids. The role of magmatic water increases in the central zones of the feeding conduit and with depth. The dual nature of fluids with the prevalence of their magmatic source is supported by S, C, O, and Sr isotopic compositions. The TC parameters of the formation of massive sulfide deposits are consistent with the data on fluid inclusions from contemporary sulfide mounds on the oceanic bottom.

The Talazhin plagiodunite–troctolite–anorthosite–gabbro massif (East Sayan): petrogeochemistry and ore potential

The petrology and ore potential of the Talazhin massif located in northwestern East Sayan are studied. The internal structure of the intrusion, the petrographic composition of its rocks, and their metallogenic, petrostructural, and petrogeochemical features are considered. The probable temperature and chemical composition of the parental magma of the pluton were computed using the KOMAGMAT-3.52 program on the modeling of equilibrium crystallization. The obtained data indicate that the Talazhin massif is a rhythmically layered plagiodunite–troctolite– anorthosite–gabbro intrusion formed from low-Ti high-alumina olivine–basalt melt. It is promising for Cu–Ni–PGE mineralization.

Potential Indonesia Ores as Raw Material for Producing Iron Nugget

Indonesia due its archipelago has so many kinds of rocks which contain ores. With the finding in technology iron source is not iron ore alone like it use to be in the past. This research is conducted to see availability of mineral rocks in Indonesia as iron source. Four different kinds of mineral rocks are used. They are: limonite, saprolite, malachite, and chalcopyrite. Separation of limonite is done by magnetic separation process while saprolite, malachite, and chalcopyrite are done by washing separation methods. Analysis on Fe content is done at origin and roasting condition for all rocks. The results show that other mineral rocks can become iron source, separation will enhance Fe content, and lateritic nickel rocks especially limonite can be new other iron source.

Some Notes on the Lugiin Gol, Mushgai Khudag and Bayan Khoshuu Alkaline Complexes, Southern Mongolia

Volcanic-plutonic alkaline complexes from Lugiin Gol, Mushgai Khudag and Bayan Khoshuu, southern Mongolia (244, 139 and 131 Ma, respectively) occur within grabens in E-W lineaments. They are represented by syenitic rock-types (silica undersaturated to slightly silica oversaturated) potassic rocks and are associated to stockworks of carbonatitic veins, dykes and so on. Geochemical characteristics and isotope systematics point to a veined mantle source particularly enriched in LILE and LREE. The carbonatitic veins show high contents of Ba, Sr, Th and REE and are suitable as potential ore deposits.

High-resolution 2D seismic imaging and forward modeling of a polymetallic sulfide deposit at Garpenberg, central Sweden

We acquired a high-resolution 2D seismic profile to test the capability of the seismic method in imaging a sulfide ore body at Garpenberg, central Sweden. Delineation of the geologic structures, which surround and host the ore body, is another goal of the survey. Due to the 3D geology of the structures, a cross-dip correction performed to image out-of-the-plane reflections, resulting in a clear high amplitude anomaly at a time and location to that to be expected from near the top of the ore body. Furthermore, DMO processing and migration are applied to the data, providing images of four main reflection groups. The reflections have been interpreted as corresponding to geologic rock units in the area that partly interfere with the potential ore body signal. To further investigate the seismic response of the ore body, forward modeling by ray-tracing is applied using the ore body geometry as mapped by drilling. We use two ray-tracing approaches: standard 3D ray-tracing and an exploding reflector approach. Seven representative samples from the mine area are used to determine P-wave velocities. The measurements show a considerable contrast between the ore body and host rock. By comparing the modeled and observed data, we find that the high amplitude signal in the real seismic section most likely emanates from near the top of one concentrated ore which lies inside the larger mapped ore body that has been modeled as a resource. The base of the ore body is only observed on the synthetic data whereas a signal penetration analysis suggests that the seismic signal penetrated efficiently along the entire survey line. Presence of disseminated ore and lower fold toward the northern end of the profile could be combined reasons that make imaging the base of the ore body difficult.

Spinifex biogeochemistry across arid Australia: Mineral exploration potential and chromium accumulation

Spinifex (Triodia spp.) grasslands cover vast areas of arid Australia, across a variety of soils and landscapes. These grasses are deep rooted and long lived, hence have great potential as a biogeochemical sampling medium for mineral exploration. This study discusses the results of analyses of Triodia pungens and Triodia scariosa from field sites over buried Au mineralisation (Coyote, Oberon and Tunkillia Prospects). At each site there is a multi-element anomaly in the vegetation over the projected mineralisation, the haloes are of different scales depending on the local landscape setting and dispersion potential of each element associated with mineralisation. The magnitude of the anomalies is similar for each site independent of underlying substrate. Overall, spinifex chemical composition has the potential to act as a point indicator of substrate geochemistry with very minimal dispersion (hundreds of metres only) that can delineate the extent of a potential ore deposit.This study also discusses the Cr accumulation potential of T. pungens and T. scariosa, discovered during the mineral exploration studies, from several field sites (Coyote, Oberon, Tunkillia and North Miitel Prospects). Triodia species are shown to be able to accumulate Cr up to potentially toxic levels independent of substrate concentration. This could be due to accumulation (active transport) or the lack of a barrier mechanism (passive uptake) within the plant.

The Early Paleoproterozoic Monchegorsk layered mafite-ultramafite massif in the Kola Peninsula: Geology, petrology, and ore potential

The Early Paleoproterozoic Monchegorsk Complex is exposed over an area of 550 km2 and comprises two layered mafite-ultramafite intrusions of different age: the Monchegorsk pluton of ultramafic and mafic rocks and the predominantly gabbroid Main Range Massif (also referred to as the Moncha-Chuna-Volch’i Tundras Massif), which are separated by a fault. Both massifs consists of intercalating cumulates (first of all, Ol ± Crt, Ol + Opx ± Crt, Opx, Opx + Pl ± Cpx, and Pl), they were produced by similar melts of siliceous high-Mg series but differ in the stratigraphy of their cumulates: while the Monchegorsk pluton is dominated by ultramafites, the Main Range Massif consists mostly of gabbroids, first of all, of gabbronorites. The complex is accompanied by PGE-Cu-Ni ore mineralization, low-sulfide Pt-Pd mineralization, and chromite mineralization. Judging from geological data and isotopic dates, the Monchegorsk Complex is a long-lived magmatic center, which evolved over a time span of 50 Myr at 2.50–2.46 Ga. The Main Range Massif is younger and likely truncates the western continuation of the Monchegorsk pluton. The complex is spatially restricted to the zone of the Middle Paleoproterozoic regional Central Kola Fault and is now tectonic collage whose rocks were variably affected by overprinted metamorphism in the course of deformations. These processes most significantly affected rocks along the peripheries of the Monchegorsk pluton in the south. These rocks were completely transformed under greenschist-facies conditions but often preserved their primary textures and structures. The processes overprinted both the marginal portions of the pluton itself and the rocks of its second phase, which are accompanied by economic low-sulfide PGE deposits. The PGE-Cu-Ni ore mineralization of the Monchegorsk Complex is genetically related to two distinct evolutionary episodes with a quiescence period in between: (1) The emplacement of large layered mafite-ultramafite intrusions at 2.5–2.45 Ga. Economic deposits of sulfide Cu-Ni ores with subordinate PGE mineralization occur within the Monchegorsk pluton, and the moderate-grade low-sulfide PGE ores are related to its second evolutionary phase (in the foothills of Vuruchuaivench and in the Moroshkovoe Lake, and Southern Sopcha areas). The primary magmatic ore mineralization is predominantly Cu-Fe-Ni sulfide with PGE bismuthides-tellurides. (2) The Monchegorsk Complex was involved in the zone of the Central Kola Fault at 2.0–1.9 Ga and was broken in a collage of tectonic blocks. The rocks were sheared along the boundaries of the blocks and were affected by overprinted metamorphism, which proceeded under greenschist-facies conditions in the structures surrounding the Monchegorsk pluton in the south. Thereby the primary PGE-Cu-Ni ore mineralization underwent metamorphic processes was recrystallized with the formation of Pt-Pd arsenides, stannides, antimonides, selenides, etc. This processes was associated with the partial redistribution of PGE with their local accumulation (up to economic concentrations), and the orebodies themselves acquired diffuse outlines. In other words, the second episode was marked by the transformation of the older primary magmatic ore mineralization.

Red Mud Characterization Using Atomic and Nuclear Analytical Techniques

Red mud is a toxic waste left as a byproduct in aluminum production Bayer process. Since it contains significant concentrations of other chemical elements interesting for industry, including Rare Earths Elements (REEs), it is also potential secondary ore source. Recent events in some countries have shown that red mud presents a serious environmental hazard if not properly stored. The subject of our study is evaluation of the red mud elemental composition, especially yttrium, scandium, gallium and REEs, from an ex-aluminum plant in Obrovac, Croatia, left from the processing of bauxite mined during late 70's and early 80's at the eastern Adriatic coast and stored in open concrete basins for more than 30 years since then.

Metallogenic Prognosis Significance of Circular Structures in Porphyry Copper Deposits: A Case Study of Yulong-Malasongduo Area

Porphyry is an important basis for delineating the smallest prospecting area in resource potential evaluation of the porphyry copper deposit.Studies show that many remote sensing circular structures have a relationship with the magmatic activity(including porphyry).In order to evaluate ore potential of the porphyry copper deposit rapidly,the authors made ore prognosis in the Yulong-Malasongduo porphyry copper ore district by using remote sensing technique.Firstly,on the basis of ETM+ images,the circular structure indicators were established.Then,the circular structures in the study area were interpreted,the distribution characteristics of circular structures were summarized,and the deductive indicators of porphyry from circular structures were determined.The results show that circular structures can offer an important clue to delineating the smallest prospecting area of the porphyry copper deposit.

Direct data on the ore potential of acid magmas of the Uzel’ginskoe ore field (Southern Urals, Russia)

Direct data on the ore potential of acid magmas of the Uzel’ginskoe ore field (Southern Urals, Russia)

Geophysical modelling of the central Skellefte district, Northern Sweden; an integrated model based on the electrical, potential field and petrophysical data

Abstract The central Skellefte district (CSD) is a part of a major ore-bearing district in northern Sweden. Studying the depth and patterns of the contact relationship between the two major stratigraphic units of the CSD, the Skellefte Group and the Vargfors Group, is a key issue to understand the geometry and structure of the area and to guide exploration of base metals. In this study, we interpret geoelectrical data collected along two profiles and magnetic and gravity data obtained from the database of the Swedish Geological Survey (SGU) and Boliden Mineral, to reveal contact relationship and depth extension of the major geological structures. Petrophysical analyses of the different lithologies were conducted on samples from the database of the SGU. Electric resistivity, induced polarisation (IP), magnetic susceptibility and density were determined on 154 core samples representing the different lithologies of the area. The resistivity/IP data were acquired to define structural relations down to a maximum depth of ~ 430 m. The major contact between sediments of the Vargfors basin and volcanic rocks of the Skellefte Group were outlined from the inversion of the resistivity/IP sections, suggesting a synform boundary between the Vargfors Group and Skellefte Group. The contact relationship between the felsic and mafic volcanic rocks of the Skellefte Group is also understood with the help of the resistivity/IP data. The resistivity models were tested using the magnetic data and magnetic susceptibility inferred on the resistivity bodies. The result suggests a good correlation between the initial resistivity model and the magnetic and gravity field calculated from that model. The integration and interpretation of geological and geophysical data improved the basic understanding of the geometry of CSD. Based on previous geological investigations, the potential ore deposits are believed to be found along the volcano-sedimentary contact. The result from this study can thus be used for the base metal exploration, finding the locations of potential sulphide deposits and give a better understanding about spatial relationship between different geology structures in the CSD.

Chromitites from the Braszowice-brzeźnica Massif, Lower Silesia - Potential Chromium Source for Industry?

Chromium ore is treated as an important strategic raw material. It is used by many branches of the industry. The most important applications are metallurgical, refractory and chemical. Unfortunately, no chromium ore deposits have been found in Poland until now, with the exception of two chromium ore sites described in the Lower Silesia region. These concentrations are formed by chromitite, which is rock consisting mainly of chromian spinel. They are localized within so called SudeticOphiolite rocks along the edge of the GorySowie Massif. They form typical podiform deposits, which are characterized by the high Al content of the rock. The first locality, near Tąpadla village (the Gogolow-Jordanow Massif), is better known. The ore was exploited here at the turn of the 19th century and at the beginning of the 20th century. According to the literature, 3500 tons of the ore was obtained - all the resources at this location. The second locality, situated at the Braszowice-Brzeźnica Massif, was never studied and described properly, falling into obscurity since the 19th century. During the fieldwork at the Braszowice-Brzeźnica Massif, the author has found numerous chromium ore fragments among the debris. The rising prices of chromium on the world's markets suggest that it is reasonable to study the ore quality and overall resource potential of this deposit. The preliminary studies have shown that chromitities from Braszowice are typical ores of the podiform variety, the majority texturally massive and nodular. The chemical analyses of the primary chromianspinels grains revealed that they could be treated as refractory chromite (38% wt. of Cr2O3, lower than 30% wt. of Al2O3, and Cr/Fe ratio about 3:1). However, the metamorphic processes modified the primary chemical composition of the studied ore. They caused enrichment in Fe and Cr, and a decrease in Al in comparison to the primary ore. Moreover, the whole rock chemical analyses revealed that the content of the main elements is insufficient to use the ore without enrichment processes. Furthermore, the size and number of the potential ore bodies are presumably small. Consequently, both the chemical composition and the resources of the chromium ores from the Braszowice—-Brzeźnica Massif are insufficient to allow for profitable exploitation, despite the high price of chromium.

Volcanogenic belts of the marginal sea lithosphere in the Russian Northeast and their ore potential

According to the concepts of accretionary tectonics, the region of interest was a dynamically evolving active continental margin during Mesozoic/Cenozoic time; this is reflected in the generation of nine volcano-plutonic belts that successively evolved from northwest to southeast. Most of these evolved in parallel with the present-day location of the Kuril-Kamchatka deep-sea trench: the Late Jurassic/Early Cretaceous Uda-Murgali belt (UMVB) the Uyandina-Yasachnaya (UYVB), the Oloi belt (OVB), the Late Cretaceous/Paleogene Okhotsk-Chukchi belt (OChVB), the Late Cretaceous/Paleogene East-Sikhote-Alin’ belt (ESVB), the Eocene/Oligocene Koryak-West-Kamchatka belt (KWKVB), the Oligocene/Quaternary Central Kamchatka belt (CKVB), and the Pliocene/Quaternary East Kamchatka belt (EKVB). The successively younger age of the volcanic belts since the Early Cretaceous is in correspondence with the displacement of the volcanic arc-trench system toward the Pacific Ocean. Apart from the above-mentioned volcanogenic belts, the Omolon craton terrane also contains the pre-accretionary Devonian Kedon marginal volcanogenic belt (KVB). All the volcanogenic belts and the surrounding perivolcanic zones of tectono-magmatic activation (TMA) form the world-largest metallogenic province with a polychronous volcanogenic-plutonogenic metallization of various compositions.

Conditions for the formation and ore potential of the fluid-explosive formations of gold deposits in the Eastern Transbaikalian region

In the Eastern Transbaikalian region, fluidexplo� sive formations (FEFs) occur in many gold, molybde� num, and rear metal ore deposits (13). They have been identified in the Darasun (11), Baleiskoe (8), Ilinskoe (14), and Klyuchevsk gold deposits and the Zhireken, Shakhtaminskoe molybdenum, and Sherlova Gora tinore polymetallic deposits. This work is aimed to establish the geodynamic environments of the forma� tion of the fluidexplosive formations in gold deposits of the Eastern Transbaikalian region, to define their petrochemical and geochemical specialization and features of the gold mineralization localization. This work is based on actual material, collected during thematic works, carried out by the Institute of Natural Resources, Ecology, and Cryology at the Del'machik, Ilinskoe, Andryushkinskoe, and Klyu� chevsk gold deposits.

Formation Conditions and ore potential of black shales of the Udokan Group, East Siberia

Peculiarities of formation and ore potential of black shales of the Paleoproterozoic Udokan Group are considered. They are compared to the stratotype (Khokholma Formation, Sukhoi Log gold deposit). The black shales are confined to lower parts of the Paleoproterozoic sequence of the Udokan Group. They are observed in sections of the Chitkanda, Inyr, Ayan, and Ikab’ya formations. The black shale complex of the Udokan Group is divided into three levels of Au concentration. The first level with background Au contents is typical of barren shales; the second level is confined to sulfidized rocks; and the third level is related to sulfide-quartz veins in the black shales. The average Au content is 0.12 g/t in the sulfidized shales and 0.28 g/t in the sulfide-quartz veins. Black shales of the Udokan Group and Khokholma Formation were formed in a relatively deep shelf zone, while those of the Shaman Formation precipitated in a shallow zone. Protoliths of black shales of the Udokan Group contained graywackes, diorites, syenites, basic rocks, and tuffites. Protoliths of black shales of the Khokholma Formation were produced by the intense weathering of basic and ultrabasic rocks.

Dualistic distribution coefficients of elements in the system mineral-hydrothermal solution. I. Gold accumulation in pyrite

The use of trace elements (TE) as geochemical indicators is complicated by the dualism of their distribution coefficients D due to the additional (i.e., above the concentrations of an isomorphic component) incorporation of elements at structural defects of various nature (including the surface of the crystal). A pressing problem in this situation is to determine the true D values that pertain to the structural component of an admixture Dstr and evaluate effects of other modes of TE occurrence. Only upon distinguishing Dstr in the bulk coefficient Dbulk it is possible to evaluate the ore potential of fluid in terms of certain TE from the composition of a mineral containing the TE. Pyrite synthesized in solutions of variable pH at 450°C and 1 kbar (100 MPa) at fluid portions sampled in a trap is utilized to demonstrate the role of a surface nonautonomous phase (NP) in the incorporation of gold in this mineral. The distribution coefficient of gold between pyrite and hydrothermal solution is 0.14 for “pure” pyrite and 0.05 for As-bearing pyrite (containing 0.02–0.05 wt % As), and these coefficients for NP are 310 and 170, respectively. This increases the Dbulk for evenly distributed (“invisible”) gold by factors of four and nine. In contrast to the results of earlier studies conducted at room temperature and pressure or parameters close to them, our data demonstrate that the accumulation of “invisible” Au in pyrite is controlled not only by reducing adsorption with the development of Au(0) particles and films but also by Au incorporation in NP developing in the surface layer of the crystal approximately 500 nm thick as chemically bound Au [most likely as Au(I)]. The possible reason for the high absorption capacity of NP is the defect (pyrrhotite-like) structure, which is not saturated with bonds of excess S and sulfoxi onions.

Redox problems in the “metallogenic specialization” of magmatic rocks and the genesis of hydrothermal ore mineralization

Considering the history and current state of the problem of the so-called metallogenic specialization of magmatic rocks, the paper places emphasis onto various aspects of the genesis of ore mineralization depending on the redox state of magmas (as a logical continuation of S. Ishihara’s works), fluids, and host rocks. These problems were inadequately poorly explored and discussed by researchers dealing with ore deposits. Various possible variants of ore-forming redox processes for different types of mineral deposits, with ore mineralization affiliated to granites (Ta, Sn, W, Mo, and Be) and mafic magmas (Au, Ag, U, Cu, Zn, Pb, As, Sb, and Hg) and, accordingly, to crustal and mantle origin, are discussed. On the basis of analyzed geological data, including those published over the past three decades, it is shown that the redox state of ore-producing magmas commonly significantly impacted not only the ore potential of magmatic complexes but also the genetic type of the ore mineralization. The redox state of the fluids predetermined the transport and precipitation speciation of metals. Influence mechanisms of hydrocarbons from sedimentary country rocks and gaseous products of their pyrolysis on ore deposition of various metals are considered. Understanding these mechanisms can be helpful for predicting the possible precipitation sites of ore mineralization of noble, radioactive, and chalcophile metals.

Worldwide potential for ex-situ mineral carbonation

World data on (i) CO2-emission sites and (ii) ore deposits in mafic/ultramafic (M/UM) rock contexts have been crossed through a GIS (under ArcGIS) in order to identify sites of potential interest for implementing the ex-situ carbonation method. Applying relevant criteria, such as the nature and quantity of mining waste, volumes of CO2 e mission, distance between mine and emission sites, and adding mining data from the literature, has led to a selection of eight potential ore deposits in an ultramafic rock context. These are located in Botswana, South Africa, China, Russia and Kazakhstan, and all lie within a 300 km radius of coal-fired industrial plants emitting >1 Mt/year CO2. This approach is but a first level of reflective thinking that could be complemented by applying hydrographic, topographic, chemical and mineralogical, economic, and even political criteria.