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Es-Sbikhat- El-Mahmel, basin, located at the southeastern piedmont of Aures massif (Northeasten Algeria), is an area with a semi-arid climate. 39 samples were collected during May 2015, for physicochemical analysis. The interpretation of analysis data has shown a chemical facies evolution from bicarbonate-calcium waters into chloride-calcium waters, going through a transition facies marked by sulfate-calcium to sulfate-magnesium waters. The principal component analysis showed that the percentage of the variances expressed is 52.70% for the factor 1, 14.73% for the factor 2 and 11.44 for the factor 3. The binary diagrams and thermodynamic analysis corroborated that interaction water-rock is responsible for the mineralization through the geochemical process of mineral dissolution-precipitation, cationic exchange and anthropogenic pollution.

This fifth paper on Scottish mineral Geological Conservation Review (GCR) sites details sites of highest conservation value for hydrothermal veins and associated mineral assemblages. The GCR sites are both large and small reflecting variations in past economic mining and extraction history. During the long mining histories, and after, the sites have yielded new mineral species and a new metal. From the largest ore field for lead, zinc and copper 80 or so minerals have been recognised, including nine new species, one of which was established as the first sulphite, scotlandite. Elsewhere gold and silver were also extracted. For some veins the country rocks were analysed to determine whether they provided the vein elements for primary and secondary minerals, and sometimes dated. Two sites exhibit polymetallic mineralization, i.e., five elements in the mineral assemblages. In one site veins in close proximity to a sanukitoid pluton received signature elements from the intrusion. Veins in various areas formed in faults, fractures and shears which became conduits for ground waters reacting with vein minerals. Oxygen in the water reacted with lead, zinc and copper minerals and in the presence of CO2 and SO4 supergene mineral assemblages formed in appropriate alkalinities. It is therefore possible to establish paragenetic sequences and calculate stability fields for specific assemblages. Alkalinities and formation temperatures may also be obtained through fluid inclusions studies and isotope analysis.

This, the fourth paper on Scottish Mineral GCR sites, deals with minerals produced during the late stages of granitic rocks creation. Five sites are described and interpreted, encompassing both minerals within intrusive rocks and those which formed in the adjacent country rocks. The former range from previously-mined, porphyry-style copper-molybdnum sulphide concentrations to one of the few Scottish occurrences of tungsten mineralization. Mineral deposits formed in mostly calcareous country rocks by the exchange of elements between granitic bodies and them are generally referred to as skarns. They are geographically more widespread than the within-granite bodies, and comprise calc-silicate minerals such as diopside, grossular garnet, wollastonite and, more rarely vesuvianite. In one instance, the skarns contain a wide range of mineral assemblages including some with boron fluoride minerals and mineable concentrations of iron ore. Probably the most enigmatic of these is an apparent exoskarn type assemblage but is devoid of an associated granite.

The Westwood deposit, located in the Archean Doyon-Bousquet-LaRonde mining camp in the southern Archean Abitibi greenstone belt, contains 4.5 Moz (140 metric t) of gold. The deposit is hosted in the 2699–2695 Ma submarine, tholeiitic to calc-alkaline volcanic, volcaniclastic, and intrusive rocks of the Bousquet Formation. The deposit is located near the synvolcanic (ca. 2699–2696 Ma) Mooshla Intrusive Complex that hosts the Doyon epizonal intrusion-related Au ± Cu deposit, whereas several Au-rich volcanogenic massive sulfide (VMS) deposits are present east of the Westwood deposit. The Westwood deposit consists of stratigraphically stacked, contrasting, and overprinting mineralization styles that share analogies with both the intrusion-related and VMS deposits of the camp. The ore zones form three distinct, slightly discordant to stratabound corridors that are, from north (base) to south (top), the Zone 2 Extension, the North Corridor, and the Westwood Corridor. Syn- to late-main regional deformation and upper greenschist to lower amphibolite facies regional metamorphism affect the ore zones, alteration assemblages, and host rocks. The Zone 2 Extension consists of Au ± Cu sulfide (pyrite-chalcopyrite)-quartz veins and zones of disseminated to semimassive sulfides. The ore zones are spatially associated with a series of calc-alkaline felsic sills and dikes that crosscut the mafic to intermediate, tholeiitic to transitional, lower Bousquet Formation volcanic rocks. The metamorphosed proximal alteration consists of muscovite-quartz-pyrite ± gypsum-andalusite-kyanite-pyrophyllite argillic to advanced argillic-style tabular envelope that is up to a few tens of meters thick. The North Corridor consists of auriferous semimassive to massive sulfide veins, zones of sulfide stringers, and disseminated sulfides that are hosted in intermediate volcaniclastic rocks at the base of the upper Bousquet Formation. The Westwood Corridor consists of semimassive to massive sulfide lenses, veins, zones of sulfide stringers, and disseminated sulfides that are located higher in the stratigraphic sequence, at or near the contact between calc-alkaline dacite domes and overlying calc-alkaline rhyodacite of the upper Bousquet Formation. A large, semiconformable distal alteration zone that encompasses the North Corridor is present in the footwall and vicinity of the Westwood Corridor. This metamorphosed alteration zone consists of an assemblage of biotite-Mn garnet-chlorite-carbonate ± muscovite-albite. A proximal muscovite-quartz-chlorite-pyrite argillic-style alteration assemblage is associated with both corridors. The Zone 2 Extension ore zones and associated alteration are considered synvolcanic based on crosscutting relationships and U-Pb geochronology and are interpreted as being the distal expression of an epizonal magmatic-hydrothermal system that is centered on the upper part of the synvolcanic Mooshla Intrusive Complex. The North and Westwood corridors consist of bimodal-felsic Au-rich VMS-type mineralization and alteration produced by the convective circulation of modified seawater that included a magmatic contribution from the coeval epizonal Zone 2 Extension magmatic-hydrothermal system. The Westwood Au deposit represents one of the very few documented examples of an Archean magmatic-hydrothermal system—or at least of such systems formed in a subaqueous environment. The study of the Westwood deposit resulted in a better understanding of the critical role of magmatic fluid input toward the formation of Archean epizonal intrusion-related Au ± Cu and seafloor/subseafloor Au-rich VMS-type mineralization.

Iron oxide copper-gold (IOCG) deposits are major sources of Cu, contain abundant Fe oxides, and may contain Au, Ag, Co, rare earth elements (REEs), U, and other metals as economically important byproducts in some deposits. They form by hydrothermal processes, but the source of the metals and ore fluid(s) is still debated. We investigated the geochemistry of magnetite from the hydrothermal unit and manto orebodies at the Mina Justa IOCG deposit in Peru to assess the source of the iron oxides and their relationship with the economic Cu mineralization. We identified three types of magnetite: magnetite with inclusions (type I) is only found in the manto, is the richest in trace elements, and crystallized between 459° and 707°C; type Dark (D) has no visible inclusions and formed at around 543°C; and type Bright (B) has no inclusions, has the highest Fe content, and formed at around 443°C. Temperatures were estimated using the Mg content in magnetite. Magnetite samples from Mina Justa yielded an average δ56Fe ± 2σ value of 0.28 ± 0.05‰ (n = 9), an average δ18O ± 2σ value of 2.19 ± 0.45‰ (n = 9), and Δ’17O values that range between –0.075 and –0.047‰. Sulfide separates yielded δ65Cu values that range from –0.32 to –0.09‰. The trace element compositions and textures of magnetite, along with temperature estimations for magnetite crystallization, are consistent with the manto magnetite belonging to an iron oxide-apatite (IOA) style mineralization that was overprinted by a younger, structurally controlled IOCG event that formed the hydrothermal unit orebody. Altogether, the stable isotopic data fingerprint a magmatic-hydrothermal source for the ore fluids carrying the Fe and Cu at Mina Justa and preclude significant input from meteoric water and basinal brines.

The Wujiaping Sn deposit is located at the northern Dayishan ore field, South China, whose ore veins are mainly hosted in the Dayishan pluton. LA–ICP–MS zircon U–Pb dating for the medium-fine grained- and medium-coarse grained-biotite monzogranite of Dayishan pluton yields emplacement ages of 154.5 ± 1.6 Ma (MSWD = 2.0) and 155.5 ± 0.5 Ma (MSWD = 1.9), respectively, which are consistent with the muscovite 40Ar-39Ar plateau age of 150.4 ± 0.9 Ma for the quartz vein type ore veins. It is indicated that the Sn mineralization in the Wujiaping deposit is related to the Late Jurassic granitic magmatism. These granites show the geochemical features of highly fractionated S-type granite: 1) low Zr + Nb + Ce + Y contents ( 1.1); 3) low crystallization temperature (mean = 688 °C); 4) high Rb/Sr ratios (mostly > 48); 5) high differentiation index (DI > 90); and 6) low CaO, P2O5, Sr, and Eu contents. Whole rocks isotopes show that these granites shows variable initial 87Sr/86Sr ratios (0.70251–0.71208), negative eNd(t) values (−7.94–5.62) and old two stage Nd model ages of 1491–1563 Ma. LA–MC–ICP–MS zircon Lu–Hf isotopes show that the medium-fine-grained monzogranite have positive eHf(t) values of 0.37–8.5 and two stage Hf model ages of 662–1180 Ma, whereas the medium-coarse grained-biotite monzogranite have negative eHf(t) values of −6.42–3.55 and two stage Hf model ages of 1431–1599 Ma. It is proposed of that these granites are originated from melts mixed by crustal- and mantle-constituents and are formed in an extensional setting caused by the subduction of the Palaeo-pacific plate. The low LogfO2 values calculated through zircons (−21.2–13.1) and high F contents (3630–5120 ppm) indicate the granites derived from reduced and F-rich melts. Therefore, the reduced melt is highly fractionated and enriched in Sn and F, resulting in the large scale Sn mineralization in the Dayishan ore field.

Discovering ore deposits is becoming increasingly difficult, and this is particularly true in areas of glaciated terrains. As a potential exploration tool for such terrains, we test the vectoring capacities of trace element and sulfur isotope characteristics of pyrite, combined with quantitative statistical methods of whole-rock geochemical datasets. Our target is the Rajapalot gold–cobalt project in northern Finland, where metamorphosed Paleoproterozoic volcanic and sedimentary rocks of the Peräpohja belt host recently discovered gold prospects, which also have significant cobalt enrichment. The focus is particularly put on a single gold–cobalt prospect, known as Raja, an excellent example of this unusual cobalt-enriched gold deposit, common in the metamorphosed terranes of northern Finland. The major lithologies at Rajapalot comprise amphibolite facies metamorphosed and polydeformed calcsilicate rocks that alternate with albitic units, mafic volcanic rocks, mica schist and quartzite. Mineralization at Rajapalot prospects is characterized by an older Co-mineralizing event and a younger high-grade Au mineralization with re-mobilization and re-deposition of Co. Detailed in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful technique that produces robust trace element and sulfur isotope databases from paragenetically and texturally well-characterized pyrite from the Raja prospect. The results are treated with appropriate log-ratio transformations and used for multivariate statistical data analysis, such as the computation of principal components. Application of these methods revealed that elements such as Co, Ni, Cu, Au, As, Ag, Mo, Bi, Te, Se, Sn, U, Tl and W have high vectoring capacities to discriminate between Co-only and Au–Co zones, as well as between mineralization stages. The systematic pyrite study suggests that homogenous sulfur isotopic characteristics (+1.3 ‰ to +5.9 ‰) and positive loadings of Co, Se, As, Te, Bi and Au onto PC1 are reflective of an early stage of Co mineralization, while the opposing negative loadings of Mo, Ni, W, Tl, Cu and Ag along PC1 are associated with pyrites from the Au-mineralizing event. The sulfur isotopic signature of the latter pyrite type is between −1.2 ‰ and +7.4 ‰. Subtle patterns recognized from the whole-rock geochemistry favor an As–Au–Se–Te–W–U signature along the positive axis of PC1 for the localization of high-grade Au–Co zones, whereas the element group Ni, Cu, Co, Te, Se and As, which has negative loadings onto PC2, will predict Co-only zones. This study shows the efficiency of trace element geochemistry in mineral exploration targeting, which has the capacity to define future targets by characterizing the metallogenic potential of a host rock, as well as distinguishing various stages of mineralization.

The Qin–Hang suture belt in South China formed during the Neoproterozoic amalgamation between the Cathaysia and Yangtze blocks. There are several Jurassic porphyry–skarn Cu deposits in this region, and the factors controlling the mineralization potential remain unclear. This study reports geochemical data for the Tongshan skarn deposit and zircon trace element data for five porphyry- or skarn-type Cu deposits in this region, in order to identify geochemical indexes for the mineralization potential of the ore-related intrusions. A garnet U–Pb age (170 Ma) for the Tongshan skarn indicates that Cu mineralization occurred in the Middle Jurassic, which is consistent with the zircon U–Pb ages (173 Ma–171 Ma) of the host granodiorite porphyries. Granodiorite porphyry samples from the Tongshan deposit have moderately high SiO2 contents (64.4–65.0 wt%), low MgO contents (1.39–1.47 wt%), and high (La/Yb)N ratios (14.7–16.8), typical of low-Mg adakitic rocks. The whole-rock geochemistry, bulk Earth-like eNd (t) values (–1.5 to –1.6) and positive zircon eHf(t) values (+2.7 to +6.0), corresponding to two-stage Hf model ages of 1014–832 Ma, suggest the porphyries were derived from thickened juvenile lower crust initially generated during Neoproterozoic amalgamation. In addition, the porphyry samples have arc-like geochemical characteristics (Nb–Ta–Ti depletion), low Th/Yb ratios (average = 4.7), high Ba/Th ratios (average = 346), zircon Eu/Eu* values (average = 0.71) and 10000×(Eu/Eu*)/Y values (average = 6.80), and moderate zircon Ce/Ce* values (average = 705) and Ce/Nd ratios (average = 17.1). These features demonstrate that the parental magmas of the porphyries were formed by melting of a mantle wedge. That had been metasomatized by moderately oxidized slab-derived fluid near a Neoproterozoic subduction zone. Previous studies suggest porphyries from large to giant deposit (e.g., Dexing and Yinshan) have similar two-stage Hf model ages and were derived from Neoproterozoic juvenile crust. But these porphyries have higher whole–rock Th/Yb ratios and zircon Ce/Ce* and Ce/Nd values than those of intrusions from medium-sized deposits (e.g., Tongshan, Chuankeng and Jiande). This indicates that the magma source of the former may have been distant from the trench in the Neoproterozoic, and formed by melting of a mantle wedge that had been metasomatized by highly oxidized slab-derived melt. Our results and previously published data indicate that the Neoproterozoic two-stage Hf model ages of the intrusions are positive indicators of Jurassic Cu mineralization, and granitoids with relatively high Th/Yb ratios and zircon Ce/Ce* and Ce/Nd values likely have more potential to form large to giant Cu deposits.

The first record of the carbonate-hosted Pb-Zn deposits in Turkey dates back to the Roman period. The carbonate-hosted Pb-Zn deposits in Turkey are economically important and found in the Aladaglar - Zamanti Province. Mineral exploration and geological mapping through the utilization of the traditional geological method still remain very challenging in many high terrains (High mountains). In this study, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data were used for mapping the carbonate-hosted Pb-Zn deposits in the Yahyali region of Turkey. The Band Ratio (BR), Least square fitting methοd (Ls–fit), Band Ratio Color Composite (BRCC), and Principal Cοmpοnent Analysis (PCA) were used tο map the Pb-Zn mineralization zone. The results of this investigation show the spatial distribution of Fe-Mg – OH/CO3, hydroxyl-bearing and iron oxide minerals. Field work and laboratory analysis were carried out to verify the occurrence of alteration zones and highly prospective locations and to confirm the availability of alteration and potential zones of carbonate-hosted Pb-Zn mineralization in the study area. Spatial correlation and distribution were observed between the previous geological map, active and abandoned mines, and the result obtained from the remote sensing data. Different techniques applied to the Aster data image in this study are recommended fοr carbonate-hosted Pb-Zn and lithological mapping in hostile terrains.

Remote sensing methods are a vital alternative for regional exploration surveys. Many ore deposits (e.g., epithermal, porphyry-related, volcanogenic massive sulphides, etc.) have distinct distribution patterns of alteration zones that can be used for recognizing this mineralization. Several known goldfields are distributed within the basement rocks of western Nigeria. The area of interest, Malumfashi Schist Belt, is located in North-Western Nigeria and is characterized by gneisses and metasediments that were intruded by Pan-African granitoids. Gold mineralization occurs as veins and veinlets that are associated with hydrothermal alteration zones (i.e., argillic, phyllic, and propylitic). Hence, the discrimination of these alteration zones is one of the key indicators for new prospective zones of gold mineralization in this metallogenic belt. In the present study, Landsat Enhanced Thematic Mapper+ (Landsat-7 ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were processed and integrated with the aim to identify possible locations for gold mineralization within the Malumfashi Schist Belt. For this purpose, the band ratio techniques and Principal Component Analysis (PCA) were applied to identify, enhance and map the different alteration types, while fractal analysis was utilized to quantify the degree of alteration within each processed image. Using the multi-criteria evaluation method, the discretized images obtained from the fractal analysis were weighted and integrated into an enhanced possible location for gold occurrences. A receiver operating curve/Area under curve analysis was then used to evaluate the reliability of the predictive model. Both spatial and GIS analyses indicate that gold mineralization displays a proximal relationship to hydrothermal alteration data. We can map sets of alteration minerals which mainly represent new and good ore prospects for the investigated area. A sensitivity analysis points out a predictive accuracy of 78%, which suggests the model is capable of predicting gold occurrences within the study region. Besides, the results showed that the prospective zones of gold accumulations mainly occur within metasedimentary units. It is recommended that the studied dataset provide a potential tool for mapping alteration minerals related to gold deposits that can be applied in other regions with analogous geological setting.

Haerdaban is a newly discovered Zn–Pb deposit (0.64 Mt at 6.19 wt% Zn and 1.09 wt% Pb) in the Western Tianshan, NW China. Sulfide mineralization mainly occurs as veins, breccias, and semi-massive ores within the dolomitic limestone and calcareous slate. Here we use Rb–Sr sphalerite and SHRIMP U–Pb zircon geochronology to place constraints on the age and formation of the deposit. Rb–Sr dating of sphalerite gives an isochron age of 432 ± 45 Ma (n = 6; 87Sr/86Sri = 0.7102 ± 0.0020), providing a direct age constraint for the main mineralization. SHRIMP U–Pb data for detrital zircon from three samples of host siliceous dolomite have relatively similar age modes with prominent age peaks at 1576 Ma, 1781 Ma, and 1848 Ma, and a smaller peak at 1375 Ma. The maximum depositional age for the host dolomite is constrained at 1099 ± 21 Ma by the weighted mean age of the four youngest detrital zircons. These results demonstrate that the main mineralization clearly postdates the host sedimentary rocks. Zircons from two diorite samples and one granite sample yield overlapping 206Pb/238U ages with a weighted mean of 394.5 ± 1.5 Ma. This age is slightly younger but within analytical uncertainty of the 432 ± 45 Ma for the ores, implying a possible temporal relationship between intrusions and main mineralization. The igneous intrusions could provide the heat to drive the hydrothermal system responsible for main-stage mineralization. Haerdaban is interpreted to be a metamorphosed SEDEX Zn–Pb deposit that has been remobilized by subsequent hydrothermal activity.

Late-stage metamorphic (ca. 2.64 Ga) and punctuated magmatic-hydrothermal mineralization models (2.67–2.64 Ga) are proposed for gold mineralization in the Kalgoorlie gold camp (~ 2300 t Au; Archean Yilgarn craton, Western Australia). We present structural, whole-rock geochemical, pyrite trace element, and multiple sulfur isotope data to evaluate these models. Both the Fimiston and Hidden Secret lodes were emplaced in ca. 2675 Ma D2b transtensional settings as releasing bends developed along the Golden Mile and Towns faults, respectively, and are related to the ingress of a H2O-CO2-Au-Te-As-S-K-Rb-Ba fluid concomitant with the intrusion of andesitic dikes. In the Hidden Secret orebody, this magmatic-hydrothermal fluid evolved from an early, As-enriched, greenstone-buffered fluid during the formation of disseminated pyrite mineralization (δ34Spyrite = 3.42 to 3.85‰; Δ33Spyrite = 0.25 to 0.43‰) to an Ag-Cu-Pb-Sb-Te-Tl-V-Zn–enriched fluid during the development of banded quartz-carbonate-sericite-pyrite veins (δ34Spyrite = - 10.74 to - 0.17‰; Δ33Spyrite = 0.06 to 0.19‰). Oroya gold-telluride lode mineralization formed during later, ca. 2660 Ma D2c transpression from a V-S–Au-Ag-Hg-Te–enriched magmatic-hydrothermal fluid represented by δ34Spyrite = - 11.56‰ to - 4.96 and Δ33Spyrite = 0.08 to 0.17‰. The Fimiston/Hidden Secret and Oroya mineralization events record oxidized magmatic-hydrothermal fluids represented by δ34Spyrite ≤ 0‰ and Δ33Spyrite ~ 0.0 to 0.2‰. These oxidized magmatic-hydrothermal fluids interacted with surrounding wall rock, which lowered fluid fO2 and buffered δ34Spyrite/Δ33Spyrite values to δ34Spyrite = ~ 1 to 5‰/Δ33Spyrite = ~ 0.2 to 0.7‰ in greenstone rock environments and to δ34Spyrite = ~ 1 to 5‰/Δ33Spyrite = ~ ≤ 0.3‰ and ≥ 0.7‰ in black shale environments. Anomalous Δ33S values in ore-stage sulfides formed locally due to the incorporation of sulfur during fluid-wall rock interaction. The early, magmatic-hydrothermal Fimiston/Hidden Secret and Oroya gold-telluride lodes differ texturally, geochemically, and mineralogically from the D3 Mt. Charlotte stockwork veins, which formed subsequent to ca. 2650 Ma and better adhere to a late-stage metamorphic devolatilization model.

The Baiyinnuo’er deposit in northern China is located in the south section of the Great Xing’an Range, and it is the largest skarn Zn–Pb deposit in the region. Skarn and Zn–Pb orebodies mainly occur between the different units of the Permian Huanggangliang Formation, or within the contact zone between the intrusive rocks and the marble. Although Baiyinnuo’er has been well investigated previously, the timing of the Zn–Pb mineralization is still controversial, largely due to the lack of appropriate ore or alteration minerals that could be directly used for isotopic dating. In this study, we report the results of Rb–Sr isotopic analysis for sphalerite and pyrite samples from the Baiyinnuo’er orebodies, which yielded two isochron ages of 137.4 ± 3.4 and 140.0 ± 7.8 Ma, respectively, constraining the Zn–Pb mineralization time of the deposit as the Early Cretaceous. The data are also consistent with the age of the granitoids in the mining area, indicating a potential genetic relationship between the Early Cretaceous magmatism and mineralization. Many other intrusion-related hydrothermal deposits (including the two typical skarns, Huanggang and Haobugao) in the southern Great Xing’an Range also share similar mineralization ages (i.e., 140–130 Ma). Together, these data suggest an Early Cretaceous mineralization event in this region, and this large-scale mineralization could be related to the regional tectonic regime transition from compression to extension as a result of the rollback of the subducted Paleo-Pacific plate. The initial 87Sr/86Sr ratios of the sphalerite and pyrite samples are 0.70569 and 0.70616, respectively, implying that the ore-forming material could have a significant contribution from the mantle components. The current study shows that sulfide Rb–Sr dating could be used in deciphering the timing of skarn deposit formation.

The Guanting Pb–Zn deposits in the Jianshui area, southern Yunnan Province, SW China, are located in the conjunction of the Yangtze Block, Cathaysian Block and Sanjiang Block, and they belong to part of the Sichuan-Yunnan-Guizhou (SYG) Pb–Zn metallogenic province. The Pb–Zn orebodies occur in basaltic and limestone breccia at the interfaces between the Maokou limestone and Emeishan basalt. Here, we use zircon U–Pb dating, Rb–Sr dating, trace elements and S isotope data of sulfides to constrain the ages and genesis of deposits. Petrological investigations reveal two main stages of mineralization. Early-stage sphalerites yield a Rb–Sr age of 251.1 ± 8.5 Ma, and it is contemporaneous with the Guanting basalt within the range of error, which has a concordant age of 247.3 ± 4.2 Ma. This metallogenic age indicates that early-stage mineralization may be related to Emeishan volcanic hydrothermal activity. Initial value of 87Sr/86Sr (0.709) and rare earth elements (REE) patterns of minerals suggest that ore-forming materials were likely derived from mixed mantle-crust sources, and paleo-seawater participated in deposition of Pb–Zn ore. There are two peaks of sulfur isotope (δ34S) in the Huangtian and Xinzhai deposits. The δ34S of early-stage sulfide is concentrated at + 1.1‰ VCDT to + 3.9‰ VCDT, suggesting that the sulfur was directly supplied by basaltic volcanic activity. Late-stage colloidal sulfides have δ34S ranging from + 6‰ VCDT to + 9‰ VCDT, suggesting marine sulfur origin, and that reduced sulfur derived from carbonate strata by thermochemical sulfate reduction (TSR). According to the geochemical characteristics, geochronology and regional geodynamic setting, we assume that early-stage mineralization in the Guanting Pb–Zn deposits is Emeishan volcanic hydrothermal mineralization, and late-stage mineralization is similar with Mississippi Valley-type (MVT) deposit. Our results provide new evidence for understanding hydrothermal mineralization associated with the Emeishan flood basalts in the SYG area.

Nitrate deposits are rare worldwide, especially potassium nitrate deposits; furthermore, their genesis remains disputed. There is a rare salt-lake type potassium nitrate deposit in the Dawadi area of Lop Nor at the eastern margin of the Tarim Basin, and the ore bodies show coexisting solid and liquid phases. Additionally, there are large sulphate-type potash deposits in the adjoining Luobei Depression, south of the Dawadi area. To determine why there are two different types of potash deposits in adjacent depressions with similar climates, field geological surveys were conducted and samples collected. It was found that the Tertiary clastic layer at the periphery of the Dawadi deposit was rich in high-salinity brine, with nitrate contents of up to 495–16,719 mg/L, much higher than those in the Luobei Depression, 1–35 mg/L. Additionally, a type of deep hydrothermal (Ca–Cl) brine was found in the fault zones, with nitrate contents of up to 8044 mg/L, dozens of times greater than that of ordinary groundwater. Using comprehensive analysis and research, we concluded that the Dawadi and Luobei depressions belong to different hydrological systems with no connection between them; thus, the two deposits belong to different metallogenic systems. Furthermore, groundwater played an important role in the mineralization of the potassium nitrate deposit, and a deep source may have been an important source of the ore-forming materials. The fault system widely developed in Lop Nor provides favorable channels for deep hydrothermal recharge, and the groundwater and deep hydrothermal brine could provide the source for the nitrate mineralization in the Dawadi Depression through water–rock reactions.

Although forming one unified class, orogenic gold deposits may be associated with a range of ore mineral assemblages controlled by a variety of gold deposition processes that have a direct impact on gold grade. Whereas, a better understanding of the deposition process may be critical for effective targeting of highly-endowed gold deposits, it is challenging to establish a direct comparison between mineral systems formed under different conditions. Accordingly our ability to predict whether contrasted mineral associations may be more or less prospective for high grade mineralization remains poor. In this paper, we compare fluid-rock interaction processes that led to the coeval formation of two contrasting gold mineral assemblages within the world-class Callie orogenic gold deposit. Stratabound and vein-hosted lodes formed within the same structural framework but with contrasting grades (∼3 g/t Au and ∼8 g/t Au, respectively). The stratabound mineralization consists of bedding-parallel sulfides in which gold is preserved in arsenopyrite micro-fractures. The vein-hosted mineralization consists of locally very high-grade (up to 10,000 ppm Au) visible gold concentrated in quartz veins. Both mineralization styles are hosted within different metasedimentary stratigraphic horizons with contrasting compositions. The stratabound mineralization occurs in iron-oxide rich siltstones whereas the vein-hosted mineralization occurs in carbonaceous siltstones. We investigate the fluid-rock interaction mechanisms of the two styles of mineralization at the Callie deposit by combining petrographic observation with whole-rock geochemistry, quantitative chlorite and gold analyses and thermodynamic modeling. Our results show that the stratabound mineralization occurred in response to sulfidation of the host-rock whereas decarbonation alteration, associated with the vein-hosted mineralization, records oxidation of the host-rock. Our investigation shows that gold deposition induced by oxidation of the host-rock produces the valuable, locally very-high grade visible gold mineralization whereas the sulfidation process lead to the formation of lower grade gold mineralization disseminated within the sulphide ore assemblage. We conclude that the nature of the host-rock applies a first-order control on the gold deposition efficiency in metasedimentary-hosted gold deposits.

As an important post-collisional magmatic product in the orogenic belt, the Himalayan leucogranites are the critical host rocks for a number of rare-metal mineralization (such as Li, Be, Cs, Rb, Nb, Ta, and Sn). However, there is still a lack of good understanding on the formation and evolution of the leucogranites. Particularly, the role of the magmatic fluids in transporting and enriching the rare elements is not clear. Here we measure Ba isotope compositions for leucogranites from the Kampa Dome of the Himalayan belt to understand the fluid activity and behavior of fluid-mobile elements during leucogranite formation. Our results show that the δ138/134Ba of leucogranites range from −1.32‰ to +0.12‰, much lower than the literature values for S-type granites and various sedimentary materials, suggesting that the Ba isotope compositions of the leucogranites does not reflect the sedimentary source signatures. Instead, their low δ138/134Ba is accompanied by non-charge-and-radius-controlled (CHARAC) twin-element (such as Nb/Ta) behaviors, clearly showing the involvement of magmatic fluids during magma evolution. Experimental studies suggest that the low δ138/134Ba of the magmatic fluids most likely results from exsolution from a large deep magma reservoir. Such fluids not only modified Ba isotope compositions of the leucogranites, but also transported many fluid-mobile metal elements which may help form the rare metal ore deposits. Therefore, Ba isotope data provide new insights into formation and evolution of magmatic fluids and exploration of the rare-metal mineralization.

Precambrian iron oxide copper-gold (IOCG) deposits are generally encountered with multistage hydrothermal overprints and hence have complex isotopic records. Precise dating of ore-forming and overprinting events and assessment of time-resolved metal sources are fundamental for understanding ore genesis. Here, we quantify the evolution history by integrating in situ U-Pb dating of texturally constrained allanite and Sm-Nd isotope data of ores and major rare earth element (REE) minerals in the breccia-hosted Lanniping Fe-Cu deposit in Kangdian region, southwestern China. The economically mineralized breccia in Lanniping Fe-Cu deposit is characterized by pervasive and texturally destructive replacement of polymictic clasts, including host metasedimentary packages, the intruded dolerite, and pre-ore halokinetic breccia. Ore minerals in cements are mainly composed of magnetite, chalcopyrite, bornite, and variable amounts of REE-rich minerals (e.g., apatite and allanite/epidote). Two types of allanite were identified in ores. Type I prismatic allanite texturally intergrown with magnetite has a SHRIMP U-Pb age of 1728 ± 20 Ma (1σ), which matches a zircon U-Pb age of 1713 ± 14 Ma (2σ) for the dolerite clasts and provides the direct age constraint on the Fe-Cu mineralization event. Type II anhedral allanite shows complex zoning and is spatially associated with, but texturally later than, magnetite, apatite, and chalcopyrite. This type of allanite yields significantly younger SHRIMP dates of 1015 ± 33 (1σ) and 800 ± 16 Ma (1σ) for cores and rims, respectively, which correspond to discrete regional magmatic events and hence record hydrothermal overprint/remobilization events of ore minerals in the deposit. Integrated Sm-Nd isotope compositions of type I allanite, apatite, and whole ores generally align along the reference Sm-Nd isochron of 1728 Ma, further confirming the primary ore formation at ~1.7 Ga. Corresponding εNd(1728 Ma) values ranging from –2.8 to 0.3 are significantly higher than those of the host metasedimentary rocks (–9.5 to –6.2) but comparable to those of contemporaneous igneous intrusions (–0.3 to 5.3) in the region, demonstrating that REE components of the primary ores were dominantly sourced from rocks of mantle-derived affinity. Both cores and rims of the younger type II allanite grains have Nd isotope compositions consistent with the unique time-evolved line of the ~1.7 Ga ores, implying that REEs incorporated into type II allanite were ultimately sourced from the primary ores in this deposit. The combined texture, chemical, U-Pb, and Sm-Nd isotope data thus demonstrate that REE remobilization was localized during post-ore hydrothermal overprint with negligible external inputs of REEs to the primary ores in the Lanniping deposit. In this contribution, we not only date primary ore formation but also recognize several younger allanite generations that record internal metal redistributions in response to post-ore tectonothermal events. Our study highlights the potential of ore-associated REE minerals such as allanite for resolving the age of multiple stages of hydrothermal events in complex ore deposits by ion probe, provided that careful examination of textural and paragenetic relationship of ores is conducted. Our finding of these younger allanite generations also exemplifies the significance of evaluation on time-resolved metal input for better characterizing the evolution history of the IOCG deposits.

Platinum-group elements (PGEs) occur in ophiolitic chromitite in the Dominican Republic as platinum-group minerals (PGMs) in spatial association with hydrothermal uvarovite and chromian clinochlore. Bulk-rock total PGE content in a single analyzed chromitite sample is of 6.54 g/t. Three main PGM types are distinguished: euhedral magmatic laurite completely encased in chromite, subhedral to euhedral Ru-Os-Fe-(Ir) compounds partially encased in chromite, and anhedral Pt-Fe–Ni-rich grains exclusively embedded in uvarovite or chromian clinochlore. The Ru-Os-Fe-(Ir) compounds are interpreted as magmatic Ru-Os sulfides that experienced desulfurization during hydrothermal alteration of the chromitites, whereas the Pt-Fe–Ni-rich grains are hydrothermal in origin. We propose a model in which the Pt-Fe–Ni-rich PGMs formed via the accumulation of nanoparticles directly precipitated from the hydrothermal fluids. An estimation of the temperature of crystallization of uvarovite and chromian clinochlore suggests hydrothermal alteration of the chromitite within the thermal range of 150–350 °C. Thermodynamic modeling shows that, within this range of temperature, Pt could be mobilized as aqueous bisulfide complexes (HS−) by S-poor, highly reducing hydrothermal fluids originated during serpentinization of the host chromitite rock. The crystallization of Ni sulfides in the chromitite would drop the S concentration of the fluid, causing the precipitation of Pt as native element. Ultimately, this process contributes to constrain the conditions for the genesis of hydrothermal PGE mineralizations in ophiolitic chromitites.

Carbonatite-related rare earth element (REE) deposits are major hosts of REE resources. REE mineralization in these deposits is generally associated with hydrothermal systems at late stages of carbonatite evolution, but the nature of ore-forming fluids and their role in concentrating REEs are not well understood. In this study, we quantified the nature of ore-forming fluids by conducting a detailed investigation on the fluid inclusions of the Dalucao carbonatite–related REE deposit, Southwest China. Based on the phases present at room temperature, three types of fluid inclusions, namely, high-density, CO2-rich inclusions, solid-bearing brine inclusions, and aqueous liquid inclusions, have been distinguished in the deposit. High-resolution Raman mapping reveals that the daughter minerals in the earliest brine inclusions are dominantly composed of sulfate (average mass proportion of 92.3%) with minor chloride (3.1%), carbonate (4.4%), and silicate (0.2%). In addition, a Raman peak of SO42– has been detected in the liquid phase of the aqueous inclusions. These new results suggest that the early, high-temperature ore-forming fluids are unique for containing extremely high concentrations of sulfate. Such sulfate-rich fluids are confirmed to be responsible for transporting appreciable amounts of REEs in the forms of REE-sulfate complexes. We further propose that deposition of REE minerals was mainly triggered by decreasing temperatures, which, as a result, reduced the solubility of sulfate in the fluids. Our new findings highlight the fact that sulfate-rich fluids tend to be more common in carbonatite-related REE deposits and play key roles in REE mineralization.

The purpose of this review is to shed light on copper deposits found in different regions of Pakistan. The geological attributes of copper deposits have been considered with their tectonic context. The porphyry copper deposits can be traced in Pakistan from the north through Kohistan Island Arc (KIA) up to the south to Chaghi Magmatic Arc (CMA). These deposits are mainly found in and around the Late Tertiary–Early Tertiary Himalayan Belt, Kohistan magmatic arc, Karakorum Block Foreland fold and thrust belt, Ophiolite Thrust belt, Suture zone and Chaghi Magmatic Arc. These deposits in Pakistan are chiefly established in different episodes of tectonic regimes, including subduction processes, oceanic island arc, continental arc, along with Chaman- OrnachNal Fault system and post-collisional settings.

The paper reports on the results of studies of ore-bearing rocks of the Ugakhan gold deposit (Bodaybo district): metasandstones, metasiltstones and carbonaceous shales. The rocks consist of quartz, feldspar (albite, orthoclase), Fe-Mg chlorite, mica (muscovite, sericite) and carbonates (calcite, dolomite, anker-ite) and accessory titanite, rutile, tourmaline, zircon and apatite. All rocks contain fragments of microfossils exhibiting striking concentric zonation with alternated dark (carbonaceous matter) and light (carbonate-mica material) layers. In a range from metasandstones to carbonaceous shales, the rocks exhibit an increase in mica amount and the content (up to 3%) of carbonaceous matter, as well as the formation of regeneration rims around relict tourmaline and zircon. The REE mineralization includes silicates (REE-bearing epidote, thorite), fuorocarbonates (bastnesite) and phosphates (monazite, xenotime, ankylite), which are closely related to U minerals (uraninite, cofnite). Bastnesite, ankylite and thorite formed due to the decomposition of earlier REE-bearing epidote, whereas monazite and xenotime are the products of decomposition of apatite. Uraninite formed during lithifcation of matrix of carbon-bearing rocks and is replaced by cofnite. The thermal analysis of carbonaceous matter and the formation temperature of chlorite calculated using chlorite geothermometer (296–371 °С) indicate the transformation of rocks under conditions of sericite-chlorite subfacies of greenschist facies of metamorphism.

This study investigated the geochemistry, mineralogy, fluid inclusion, trace and rare earth element (REE) contents and Pb, O and S isotope results of the barites formed together with Pb-Zn deposits in the region. The Buyukkizilcik barite mineralization is located in the west part of Afsin, Turkey and it can be traced through 14 kilometers in NE-SW direction within the Yoncayolu and Cayderesi Formation. The thickness of these mineralized areas reaches 7-8 m, especially in the middle and eastern part of the ore zone. Mineralization is represented by barite-antimonite-fluorite in the western part, pyrite-chalcopyrite in the middle part and galena-sphalerite in the eastern part of the mineralized zone. Fluid inclusion studies indicate that these mineralizations are formed in the epithermal phase of hydrothermal period, with liquids having 4.5 to 2% NaCl salinity values and temperatures of 105 °C to 121 °C. The barite samples were collected from Buyukkizilcik mineralization area for analysis of major oxides, trace elements, and rare earth elements (REEs) using inductively coupled plasma mass spectrometry (ICP-MS). According to the results of the analysis, it is seen that total trace element contents change from 163 to 20458 ppm and ∑REE contents are between 4.31 and 14.4 ppm. The chondrite- normalized REE patterns of the studied barites exhibit trends decrease from LREE towards HREE and have negative Ce and negative Eu anomalies. The 206Pb/204Pb; 207Pb/204Pb and 208Pb/204Pb isotope values of galena vary between 17.20 and 19.96%o; 14.1 and 16.2%; and 35.4 and 41.9%, respectively. These isotope results show that these mineralizations were originated from upper crust materials. The δ34S values in Buyukkizilcik mineralizations range from 8.2 to 14.4‰. The barite mineralization was formed by hydrothermal activity and that the δ34S values indicate an epithermal phase. The δ18O values of barites are between 17.0 and 18.5‰ and these δ18O values show that the origin of the water displayed in the hydrothermal activity is magmatic and/or magmatic mixed with meteoric water. All results indicate that the barite mineralization was deposited as vein-type by hydrothermal solutions that are transported along fractures and fault zones within the Malatya Metamorphic complexes.

Remote sensing and aeromagnetic data analyses were conducted for the characterization of basement structural elements that influence iron ore deposits and other mineralization over kabba and its surroundings. Spectral analysis suggests depth to magnetic sources range from deep, intermediate, and shallow with depths (i.e., 2.8 km, 1.5 km, and 0.3 km respectively). Three lithological zones were revealed on the Analytic Signal (AS) image which includes Meta-Sedimentary Complex, migmatite-gneiss-quartzite complexes, and undifferentiated schist and metavolcanic rocks. Structures interpreted based on first vertical derivatives (FVD), total horizontal derivatives (THD), and AS of the aeromagnetic images enabled delineation of long, deep, regional, inter-terrain linear structural features that are different f rom shallow, relatively short local intra-terrain structures. Typical potential mineralized zones are regions where the delineated structures on the AS coincide with FVD anomalies vis-a-vis zones exhibiting THD peak anomalies and high magnetic susceptibility. These characterized zones also coincide with the location of known geologically deposits of iron - ore and marble. Mineral deposits tend to be dominated regionally by the dominant structural patterns (NE-SW to ENE-WSW, NW-SE to WNW-ESE, and E-W) delineated from SRTM and aeromagnetic analysis.

The Xiadian orogenic deposit with ~ 100 t of gold resources, located in the Jiaodong Peninsula, Eastern China, shows an economically attractive gold mineralization that is spatially associated with the Zhaoping detachment fault. This study presents a combination of field investigation, 3D modeling, spatial analysis of models, and prospectivity modeling using a multi-layer perceptron deep neural network to understand the association between gold mineralization and structural deformation and to identify targets for deep exploration. The principal gold mineralization at Xiadian occurs as disseminated ore associated with strongly fractured rocks. Spatial analysis determined that gold mineralization is located primarily in convex segments (0–50 m) of the fault footwall within 150 m of the fault buffer where the dip is gentle (~ 35° to 55°). Sulfide vein ore with high Au grades is, by contrast, typically sited within steeply dipping fracture-fill distal to the Zhaoping detachment (150–250 m), consistently in areas with NE-strike and associated with steep segments of the detachment fault. The distribution of the orebodies is attributed to brittle–ductile deformation proximal to the detachment and distal brittle extension. Given the characteristics of syn-deformation mineralization and the stress regime (NW σ3, NE σ2, and vertical σ1), the NE-plunging ore shoots were interpreted as the result of auriferous fluid flow into oblique dilation zones formed by the coupled normal and dextral strike-slip movement of the Zhaoping fault. Six potential gold targets were identified sub-horizontal to, and NE-trending from, known orebodies. This study highlights the utility of 3D prospectivity modeling as a robust tool for understanding orogenic gold spatial distribution and related structural controls.

The geological and structural position of the Pepenveem and Korrida Au-Ag ore occurrences situated in the East-Chukotka segment of the Okhotsk-Chukotka Volcanogenic Belt (OCVB) was studied. The Pepenveem ore occurrence was characterized by one (volcanogenic) mineralization stage. It is localized within a graben-like monocline composed of Late Cretaceous volcanics. A relatively stable tectonic regime caused rather low temperature and pressure gradients during the ore formation and, consequently, simple mineral composition of the ores and absence of advanced argillic alteration. In contrast, the Korrida ore occurrence was characterized by two (volcanogenic and plutonogenic) mineralization stages. It is localized within a plutonogenic uplift complicated by a regional fault zone. Here, the basement of the volcano-structure, composed of island-arc volcano-sedimentary rocks, was uplifted to the surface by numerous high-angle faults. The here observed extensive development of zoned metasomatic haloes (including advanced argillic alterations), abundance of mineral species, and sharp temperature and pressure gradients could resulted from tectonic activity in a zone of interaction between the plutonic dome and deep-seated regional fault.

Iron ore is the second most abundant metal on earth. The characteristics of this iron ore usually consist of iron ore carrier minerals associated with other minerals. One area that has iron ore prospects is the Tanjung area, Bontocani District, Bone Regency. The purpose of this study was to determine the types of iron ore carrier minerals and their associations, mineralization characteristics and paragenesis of iron ore carrier minerals. The data collection technique is carried out directly in the field by taking random samples in the field according to field conditions. Laboratory analysis uses mineragraphic analysis to determine iron ore carrier minerals and their associated minerals and X-Ray Diffraction analysis to determine iron ore carrier minerals that are not identified by mineragraphic analysis. From the results of the study found iron ore carrier minerals magnetite, goethite and hematite and their associated minerals in the form of sulfide minerals in the form of pyrite, covelite and braunite. The iron ore textures found are replacement and intergrowth textures. Paragenesis of mineral deposits formed successively are magnetite, hematite, pyrite, cuprite, braunite and goethite.

Unravelling the genesis of metamorphosed mineral deposits can be complicated due to difficulties in separating between primary features and features that formed during the metamorphic overprint. Such uncertainty exists for stratabound and dolomite- and skarn-hosted Zn-Pb-Ag sulfide deposits in 1.89 Ga rocks in the Bergslagen lithotectonic unit (BLU) of Sweden, where a metasomatic vs. regional metamorphic origin for skarns has long been discussed. By integrating geological mapping with new lithogeochemical, mineralogical, and stable isotope data (C, O, S), we show that complexly zoned garnet and clinopyroxene skarns in the Sala area of the central BLU predate mineralization. Sphalerite-galena mineralization formed after the deposition of a younger, more Mn-rich ferroan diopside and andradite-grossular garnet, and is associated with phlogopite, tremolite-actinolite, chlorite, serpentine, and calcite. Mineralization in conjunction with a transition from high-T metasomatism to hydrolytic alteration is inferred. An average δ34SV-CDT of 1.6 ± 1.9‰ in sulfides is consistent with a primordial sulfur source. Trends defined by negative shifts in δ18OV-SMOW and δ13CV-PDB in dolomite and calcite are consistent with fluid infiltration at 300–500 °C. The alteration system is sharply truncated by unaltered, c. 1.89 Ga calc-alkaline granite and porphyritic intrusions, which along with F1 folding of the alteration zones and mineralization suggest that mineralization predate regional metamorphism. The Sala deposits are interpreted as Zn skarn deposits formed in conjunction with the emplacement of intrusions into penecontemporaneous marine volcanic and dolomitized limestone strata. The unusually Mg-rich mineralogy in relation to Zn skarns worldwide most likely reflects the dolomitic precursor.

—We present data on dispersed gold and associated disseminated mineralization of leucogranites controlling the location of the Dukat epithermal Au–Ag deposit. The data suggest the formation and burial of small portions of oversaturated gold-bearing fluids in hypabyssal magmatic bodies. The lower (relative to silver) contents of gold in the deposit ores and the high Ag/Au ratios (350–550) are due to the limited occurrence of oxidized gold-bearing fractions of magmatogene fluids. This limitation is explained by the active interaction of late magmatic portions of fluids and the material of the host carbonaceous volcanosedimentary unit and by the formation of an environment favorable for the concentration, migration, and deposition of manganese, silver, and nonferrous-metal compounds.

—We present results of petrographic, mineralogical, and geochemical study of all types of rocks of a multiphase pluton and consider the chemical evolution of igneous and metasomatic rocks of the Baga Gazriin Chuluu pluton, based on new precise analytical data. At the early stage of their formation, the pluton granites were already enriched in many trace elements (Li, Rb, Cs, Be, Nb, Ta, Th, and U), F, and HREE relative to the upper continental crust. They show strong negative Ba, Sr, La, and Eu anomalies, which is typical of rare-metal Li–F granites. The geochemical evolution of the Baga Gazriin Chuluu multiphase pluton at the postmagmatic stage was marked by the most intense enrichment of greisens and microclinites with lithophile and ore elements (Sn, W, and Zn) and the formation of ore mineralization. In the permeable rift zone where the Baga Gazriin Chuluu pluton is located, the fluid–magma interaction took place under the impact of a mantle plume. High-temperature mantle fluids caused melting of the crustal substratum, which determined the geochemical specifics of Li–F granite intrusions. Genesis of granitic magma enriched in Li, F, Rb, Sn, and Ta is possible at the low degrees of melting of the lower crustal substratum. The Baga Gazriin Chuluu pluton formed in the upper horizons of the Earth’s crust, where magma undergoes strong differentiation and the saturation of fluids with volatiles can lead to the postmagmatic formation of metasomatites of varying alkalinity (zwitters (greisens), microclinites, and albitites) producing rare-metal mineralization. By the example of the early Mesozoic magmatism area of Mongolia, it is shown that the formation of granites and associated rare-metal minerals is due to the interaction of mantle fluids with the crustal material and the subsequent evolution of granitic magmas.

This article investigates the effect of material size on the efficiency of flotation concentration of gold-copperarsenic ores of the Taror deposit (Republic of Tajikistan) and studies the dependence of gold recovery on the duration of the process with the purpose of developing an alternative technological scheme for processing this ore type. According to X-ray phase analysis, Taror ore samples consist of rock-forming minerals by 92%. Ore mineralization is represented by sulphide minerals, mainly arsenopyrite, chalcopyrite and pyrite, in the total amount of 8%. Ore-forming elements include iron, sulphur, arsenic and copper with the mass fraction of 6.02%, 3.26%, 1.52% and 0.82%, respectively. Gold and silver are contained in the ore in the amount of 7.35 g/t and 20.28 g/t, respectively. The oxidation state of the ore calculated by iron comprises 51.3%. According to this indicator, this ore type can be distinguished as mixed, close to the primary type. According to the conducted chemical phase analysis of gold, this ore type belongs to the category of refractory ores. Flotation concentration experiments showed that grinding the original ore to a size of 95%–71 microns increases the recovery of gold in the concentrate by 10%, compared to grinding to a particle size of 80%–71 microns. The effect of the flotation process duration on gold recovery was also studied. To achieve the maximum gold recovery in the flotation concentrate, the duration of the main flotation and control flotation should be taken equal to 14 and 12 minutes, respectively. As a result of the experiments, a relatively simple technological solution was proposed for flotation concentration of the Taror ore, which includes the main, control and cleaning stages of flotation.

Al-Gor area is a part of Southwestern Sinai of Egypt. It is considered as one of the most promising areas for mineralization in Egypt, being rich in many mineral deposits of: manganese, iron, copper, zinc, lead, cobalt, nickel, silver, gibbsite, and uranium. Besides, some industrial ore minerals such as kaolin and glass sand,… etc. are also found in this area. The area was studied by Gama-ray spectrometry to trace the radioactive anomalies, their concentrations and their relationship to the existing rocks, and by magnetic survey to study the relationship of radioactive anomalies and their trends with the trends of geological structures. The gamma-ray spectrometric maps show different levels over the surveyed area, which reflect contrasting radioelement contents for the exposed various rock types. The highest radiospectrometric levels are located in the northwest southeast direction and some scattered parts all over the study area. They are mainly associated with Um-Bogma Formation, bearing gibbsite. The study area possesses radiospectrometric ranging between 0.6 and 110.9 Ur as a total-count, 0.1 to 1.8 % for K, 0.1 to 99 ppm for eU and 0.1 to 23 ppm for eTh. The qualitative analyses of magnetic data show the existences of a number of different magnetic anomalies, with different amplitudes and frequencies as well as trends. From the application of spectral analyses of magnetic data, the regional and residual depths of magnetic anomalies can be computed. The first depth represents the regional (deep-seated) anomalies, at about 75 m and the residual (shallow-seated) anomalies, at about 20 m. The trends of the structures as derived from the spectrometric and ratio maps correspond to those inferred from the residual-component magnetic map, which reflects the effect of structures on the concentration of radioactive elements and, consequently mineralization.

The I-type Pan-African Misajé granites, situated in the Western domain of the Central African Fold Belt are among the late-to post tectonic granites that intruded the ante-Pan-African country rocks. In this study, magnetic susceptibility and geochemistry data are integrated to evaluate the productive and non-productive metal potential of these I-type plutonic granites, which comprise Leucocratic granite, Biotite granite, Biotite-hornblende granite, and granodiorites. The magnetic susceptibility of the representative rock samples of the Misajé pluton ranges from 0.001 × 10−3 SI to 33.2 × 10−3 SI. These values indicate the coexistence of both magnetite and ilmenite-series. The magnetite-series (>3 × 10−3 SI; oxidized type) constitute about 32 vol.% while the ilmenite-series ( 1) grains sizes. The Misajé plutonics are high potentially productive in Zn, Th, ilmenite, and magnetite and low productive in Sn, W and Cu though their extension remains limited, probably due to the remobilization of the ancient Paleoproterozoic crust that would have contributed to the dispersing of pre-Pan-African metal deposits.

The Helukou deposit, with proven reserves of 33 752 t WO3, is one of the newly exploited medium-scale tungsten (W) deposits in the Guposhan ore field, Nanling Range of South China. Skarn-type and less abundant altered granite-type tungsten orebodies were identified in this deposit. The ore mineralization in this district was a product of two-stage magmatism, as shown by LA-ICP-MS U-Pb dating of zircons and Re-Os dating of molybdenite. The former yielded U-Pb ages of 184.0 ± 3.6 Ma (MSWD = 0.15) and 163.8 ± 1.5 Ma (MSWD = 0.41) for fine-grained biotite granite and muscovite granite, respectively, as well as a U-Pb age of 181.5 ± 2.1 Ma (MSWD = 0.75) for zircon grains from altered granite-type tungsten ore. The latter yielded molybdenite Re-Os ages of 183.5 ± 2.8 Ma (without MSWD owing to a limited number of samples) and 163.4 ± 2.8 Ma (MSWD = 0.71) for altered granite-type and skarn-type tungsten deposits, respectively. Thus, two separate tungsten mineralization events occurred during the Early Jurassic and Middle Jurassic. Trace-element compositions suggest that scheelite I was controlled by the coupled substitution reactions of 2Ca2+ = Na+ + REE3+ and Ca2+ + W6+ = Nb5+ + REE3+, whereas scheelite II was controlled by the coupled reactions of 2Ca2+ = Na+ + REE3+ and 3Ca2+ = ☐Ca + 2REE3+ (where ☐ is a site vacancy). High Mo and low Ce contents suggest that both scheelite I and scheelite II were precipitated from oxidizing magmatic-hydrothermal fluids. Based on the mineral assemblage of the altered granite-type ores and geochemical characteristics of scheelite I [i.e., negative Eu anomalies (0.02–0.05; mean = 0.03 and STD = 0.01), and high 87Sr/86Sr ratios (0.70939–0.71932; mean = 0.71345 and STD = 0.00245)], we infer that fluid-rock interaction played an important role in modifying Early Jurassic ore-forming fluids. Scheelite II exhibits a geo-chemical composition [i.e., 87Sr/86Sr ratios (0.70277–0.71471; mean = 0.70940 and STD = 0.00190), Eu anomalies (0.14–0.55; mean = 0.26 and STD = 0.09), and Y/Ho ratios (16.1–33.7; mean = 27.9 and STD = 2.91)] similar to that of the Middle Jurassic Guposhan granites, suggesting inheritance of these features from granite-related magmatic-hydrothermal fluids. These results provide new insights into the two-stage magmatic and metallogenic history of the Nanling Range during the Jurassic Period.

Precambrian banded iron formations (BIFs) of Singhbhum-Keonjhar-Bonai iron ore belt in eastern India host several high grade iron ore deposits. The deposits have been formed due to supergene enrichment of parent BIFs by gradual removal of SiO2 and Al2O3 under continuous process of leaching. With intensity of leaching differing spatially, the deposits exhibit variation in Fegrade both laterally and vertically. The extent of such variation in space is a function of the scale at which observations are made. Modelling of spatial variabilities at observation scale provides an appropriate means to estimate spatially distributed block values. The present study focusses on spatial variability analysis, ordinary kriging (OK) and sequential Gaussian simulation (SGS) for Fegrade modelling using drill-hole exploration data of a high grade iron ore deposit located in the Singhbhum-Keonjhar-Bonai iron ore belt. Classical statistical modelling revealed a three-parameter lognormal fit to the negatively skewed Fe distribution, and a two-parameter lognormal fit to the positively skewed SiO2 and Al2O3 distributions. Spatial variability modelling revealed a spherical model fit in respect of Fe, SiO2 and Al2O3. A moderately high ratio of nugget-to-sill variance reflect intrinsic characteristic of banded nature of Fe mineralization as evident in BIFs with varying proportions of iron, alumina and silica. Blocks of 15m × 15m × 10m size equalling the dimension of a mining unit configured within a 3D volume bounded vertically between 875 mRL and 705 mRL and laterally between 310W to 540E and 260S to 1600N have been evaluated employing OK. Stacking of altogether seventeen horizontal slices vertically down from 870 mRL to 710 mRL led to an estimate of iron ore inventory as 124.48 mt with overall mean kriged estimate as 63.93% and mean kriging variance as 2.83 (%)2. Statistical regression analysis of OK estimates and original sample values provided a regression slope of 1.03, thereby qualifying the conditional unbiasedness of the OK estimates. SGS study provided multiple equi-probable realisations with histogram and spatial variability closely approximating to that of the original sample values.

The Golden Mile fault zone is a key controlling structure to the estimated 75 Moz gold endowment of the Kalgoorlie gold camp in the Yilgarn craton of Western Australia. The earliest structures in the fault are F1 folds that developed during D1 recumbent-fold and thrust deformation (

The Xing-Meng Orogenic Belt is characterized by intense and widespread Mesozoic granitic magmatism related to large-scale W mineralization. Three periods of W-mineralized granitic magmatism can be ...

Research subject. The Verkhoyano-Kolymsky areal of ore mineralization in the Far East of Russia.Data and methods. We used the state metallogenic map of Russia, Sc. 1: 2 500 000 (2000) and the gravity map of Russia Sc. 1: 2 500 000 (2001). Modeling was conducted by studying the deep structure of the earth’s crust and upper mantle from the anomalies of the density contrast of geological media in the intervals between the centers of density inhomogeneities and the surfaces of equivalent spheres.Results. 3D-distributions of density contrast (µz-parameter) in the crust and upper mantle of the Verkhoyano-Kolymsky region related to the rheological properties of geological media were analyzed. In the gravity models designed without attraction of external information, the structures of thrust, splitting, stretching, as well as the structures of central type (CTS) of the plume nature, were identified. In the regional stretching zone, at the border of lithospheric segments, the revealed Indigiro-Kolymsky and Verkhoyansk CTSs were described in 3D space. These structures are characterized by a mushroom-like upwelling of the asthenosphere, associated with heat flow anomalies. The identified structures differ in terms of asthenosphere depth, age and ore mineralization. The location of ore clusters and regions in the zones of CTS obeys concentric ore-magmatic zoning, typical for this type of structures. The central (trunk-like) zone of Indigiro-Kolymsky CTS features mainly high-temperature gold-quarts mineralization. On the periphery, along with gold areas, there are tin-tungsten, tin and complex ore mineralization areas. The majority of gold fields with low-temperature gold-sulfide, tin and polymetallic mineralization are attributed to the flanks of Indigiro-Kolymsky CTS. In the Verkhoyanska CTS, the majority of ore regions are characterized by multi-formation ore mineralization. In the central part of this structure, areas with mainly low-temperature tin, mercury-antimony and gold-silver ore mineralization are located. On the flanks, gold mineralization is either absent or subsidiary.Conclusions. As a result of a simple procedure, implying generalization of multiple decisions of the elementary inverse problem of gravity potential, main features of the deep structure of the Verkhyano-Kolima region were defined. In the regional stretch zone, at the boundary of lithospheric segments, the Indigiro-Kolimskaya and Verkhoyanskaya CTSs of the plume nature that control the location of ore deposits were identified and described in 3D space.

Penelitian ini bertujuan untuk mengetahui evolusi hidrotermal dari fluida pembawa mineralisasi yang terdapat di Pit Ramba Joring, meliputi temperatur, tekanan, densitas dan kedalaman pembentukan mineralisasi. Penelitian ini menggunakan analisis inklusi fluida. Sampel yang dianalisis merupakan sampel yang terindikasi terbentuk bersamaan dengan mineralisasi bijih (syngenetik), pada dua tekstur utama bijih yaitu batuan dengan tekstur silica vuggy yang terbentuk pada kisaran Th 331ºC hingga 394ºC, Tm -15,19ºC hingga -12,94ºC dengan salinitas 14,42 wt% hingga 14,89 wt%. NaCl equivalent dan batuan dengan tekstur brecciated terbentuk pada kisaran Th 287,8°C hingga 398,2°C, Tm -14,89°C hingga -11,76ºC serta salinitas 13,91 wt% hingga 4,87 wt%. NaCl equivalent. Korelasi positif antara temperatur homogenisasi pembentukan mineralisasi dengan salinitas larutan menandakan bahwa proses leaching yang membentuk rongga pada batuan terjadi pada stage awal proses alterasi hidrotermal yang diawali dengan proses leaching membentuk rongga (vuggy silica) yang diikuti proses silisifikasi dengan tekstur brecciated, pada fase ini berlangsung pengendapan mineralisasi. Asal larutan yang menjadi larutan pembentuk endapan hidrotermal merupakan jenis larutan basinal water-seawater dalam bentuk connate water yang masih dipengaruhi oleh air permukaan/meteoric water yang menunjukkan adanya indikasi hubungan dengan magmatic water. Densitas fluida pembentuk bijih logam berkisar pada 0,8 gr/cm3 sampai dengan 0,9 gr/cm3 sedangkan proses pembentukan bijih pada Pit Ramba Joring termasuk dalam isothermal mixing dengan sedikit pengaruh pemanasan/boiling.

The Masjed Daghi porphyry-epithermal Cu-Au-Mo deposit in the northern Arabian-Eurasian collision zone of the Alborz Magmatic Assemblage, NW Iran, is hosted by an early Miocene quartz monzodiorite to diorite intrusion that intruded Eocene volcanic rocks. Potassic, phyllic, argillic, and propylitic alterations associated with four stages of porphyry mineralization (I to IV) are distinguished. Late high-sulfidation epithermal veins of mainly quartz or quartz-barite are enclosed in concentric zones of advanced argillic, argillic, silicic, and propylitic alterations. Poly-phase brine inclusions from the stage ΙΙ porphyry mineralization have homogenization temperatures (Th) between 305 and 600 oC, with salinity from 30.2 to 73.9 wt% NaCl equivalent. Brines inclusions of stages ΙΙΙ and ΙV have Th from 192 to 466 oC and salinity from 20.6 to 59.2 wt% NaCl equivalent. These brine inclusions were trapped with vapor-rich inclusions, which have Th from 122 to 318 oC and low-moderate salinity of 0.3 to 22.3 wt% NaCl equivalent. Fluid inclusions from quartz and sphalerite in epithermal veins yielded Th ranges of 123–298 °C and 121–218 °C, and salinity ranges of 1.9–12.8 and 1.9–11.2 wt% NaCl equivalent, respectively. The δ34S values of sulfide minerals from stages ΙΙ and ΙΙΙ porphyry mineralization vary from + 0.9 to + 2.3‰, whereas the δ34S values of sulfides from the late epithermal veins range from + 1.2 to -1.1‰. These characteristics are consistent with a similar magmatic source for both the fluids of porphyry mineralization and subsequent high-sulfidation epithermal veins. The Masjed Daghi deposit that represents a telescoped porphyry-epithermal system of copper–gold mineralization in the center and peripherals of the early Miocene intrusive stocks shows both similarities and differences to other Tethyan deposits in the Alpine-Himalayan orogenic belt.

The world-class McArthur River Zn-Pb-Ag deposit is the type example of stratiform sediment-hosted deposits found in the Proterozoic basins of northern Australia. However, the McArthur River deposit is enigmatic in that, aside from a few sub-economic deposits within the same camp, other deposits of this type have not been discovered regionally. Understanding the key components of McArthur River-type mineral systems and the regional distribution of these components is crucial to further discovery. The recent discovery of the similar but pyrite-dominated system at Rosie ~ 90 km north of the McArthur River Mine sheds new light on the formation of this deposit class and provides a counterpoint to compare and contrast with the high base metal endowment at McArthur River. Stratiform pyrite mineralization at Rosie is finely laminated and is affected by erosional sedimentary processes superficially indicating it formed during sedimentation to early diagenesis and at or near the sediment–water interface. The conventional ore horizon in the McArthur River camp is the HYC Pyritic Shale Member in the lower Barney Creek Formation (~ 1640 Ma) within sub-basin architecture. Rosie is contained within a similar sub-basin architecture, but it occurs in the upper Barney Creek Formation. The absence of mineralization in the lower Barney Creek Formation at Rosie is attributed in part to prohibitive tectono-sedimentary conditions during early sub-basin development. The HYC Pyritic Shale Member equivalent is relatively thin beneath the Rosie mineralization and is only weakly enriched in hydrothermal elements. Its deposition was abruptly superseded by infill of the sub-basin by a thick barren sequence of fine turbidites. The fine turbidites were a rapid phase of accommodation space fill that diluted brines entering the sediment pile and effectively precluded hydrothermal sulfide mineralization as well as low temperature alkali metasomatism. Permissible tectono-sedimentary conditions did not return until late in sub-basin development, and by this time, sub-basin geometry had broadened and shallowed, and the hydrothermal fluid had evolved. Rosie mineralization is subsequently poorly focused and base metal deficient. The observation that sedimentation rate may play a role in mineralization is a significant addition to the field of basin-hosted mineral systems.

How to more effectively perform anomaly detection of combination information has always been an important issue for the scholars in various fields. In order to identify and extract the geochemical anomaly information related to polymetallic mineralization in the Hunjiang area, this article uses the hybrid method that combines multivariate canonical harmonic trend analysis (MCHTA), singularity analysis with radius-areal metal amount and improved adaptive fuzzy self-organizing map (IAFSOM). First, multiple sets of combination feature information with multi-dimensional variables will be obtained through the MCHTA method, which information is considered as the initial information for the subsequent analysis. Next, the singularity analysis method is used to process the combination concentration value to calculate the singularity indexes. Finally, the singularity indexes are classified by the IAFSOM method, and nine groups of sample data are obtained. The analysis results found that the samples information in fourth group covered most of the low α-values. The main conclusions in this study are as follows: (1) The MCHTA method can effectively detect the combination information related to geochemical anomaly; (2) The application of singularity analysis method with radius-areal metal amount can reveal the significant characteristics of mineralization combination elements; (3) IAFSOM can be used as an effective tool for the classification and identification of geochemical anomaly with combination information; (4) the hybrid method that combines MCHTA method, singularity analysis and IAFSOM model has a good indication significance in the prospecting of geochemical anomalies, and could provide a good method for geochemical prospecting.

The Xuancheng ore district is a newly discovered ore district within the Middle-Lower Yangtze River Metallogenic Belt (MYRMB) of Eastern China. Here we investigated the major and trace element concentrations of apatite crystallizes in ore-related intrusions from three skarn deposits with distinctive metal endowments in this region to further reveal their implications for petrogenesis, metallogenesis, and potential for polymetallic mineralization. The studied apatite samples identified as fluorapatite, display identical contents of F (2.04–3.25 wt%), whereas distinctive variations of Cl (0.04–1.42 wt%). The different correlations between Sr contents and (La/ Yb)N, (La/Sm)N, and (Sm/Yb)N reflect the differentiation process of the magma evolution in the Xuancheng area. Furthermore, the negative Eu/Eu* and Ce/Ce* correlation, and high log fO2 values (−10.02 to −17.40) of apatite studied, further indicate more oxidized and moderate oxidized environments. Apatite chemistry is characterized by LREE enriched patterns and has high (La/Yb)N ratios with a moderate negative Eu anomaly, suggesting that these plutons originated from enriched mantle mixing with various degrees of crustal components. Meanwhile, the visible differences in apatites among skarn Cu fertile, Cu-Mo fertile, and Cu-W fertile plutons were attributed to distinctive source affinities that ultimately control their metal endowments. Also, our study demonstrates that the Cl, F/Cl, and Eu/Eu* ratios in apatite can act as powerful pointers for ore varieties and mineral exploration.

Palladium mineralization was registered in the Kola superdeep borehole (SG-3) for the first time in samples from deep horizons (in the fault zone at ~10 km). A proper palladium mineral (merenskyite) with the formula Pd1.00(Te1.21Bi0.79)2.00 was detected using the analytical electron microscopy and EBSD methods. The unusually high content of bismuth in the discovered merenskyite crystal most likely indicates the lower temperatures of its formation from a bismuth-rich fluid. This is supported by numerous finds of associated bismuth minerals (native and intermetallic minerals, sulfides, tellurides, and sulfotellurides) as well. A close geochemical association of noble and rare elements was revealed in the composition of the rich and diverse ore mineralization in the samples studied. It can be argued that a new type of mineralization was discovered for the SG-3 rocks: noble metal (Au–Ag–Pd) rare-element (Bi–Te).

In the central Taupo Volcanic Zone, extensive zeolite (mordenite ± clinoptilolite) alteration occurs in late Quaternary rhyolitic vitric tuffs that were deposited in a lake formed by caldera collapse following the ~290 ka Ohakuri ignimbrite eruptions. Glass shards in lacustrine vitric tuffs of the Ngakuru Formation and in the underlying Ohakuri Formation ignimbrite are replaced by mordenite ± clinoptilolite, along with hydrothermal adularia, opal-A, opal-CT, and cristobalite. This mineral assemblage is also found in the outer alteration zones of the nearby Ohakuri and Tahunaatara epithermal gold prospects. Evaluation of whole-rock chemical analyses indicates that the zeolitized vitric tuffs show a slight gain in K, and Na, Ca loss relative to unaltered Ohakuri Formation pumice, which is reflected in the presence of hydrothermal adularia in the alteration assemblage. The mordenite ± clinoptilolite alteration is associated with siliceous sinters and hydrothermal eruption breccias that were formed in recently active (39–1.5 ka) geothermal systems. By analogy with geothermal systems elsewhere in the Taupo Volcanic Zone at Wairakei and Ohaaki, the mordenite ± clinoptilolite alteration was formed from dilute alkali-chloride aqueous liquid at 60° to 150°C. Based on the close association of the mordenite ± clinoptilolite alteration with siliceous sinters and hydrothermal eruption breccias in the central Taupo Volcanic Zone, it is classified as shallow, low-temperature, epithermal alteration. Mordenite ± clinoptilolite alteration has also been identified in Quaternary rhyolitic caldera settings in Japan and the United States, where it is termed “caldera-type zeolitization.” In exploration for epithermal Au-Ag deposits in rifted arc settings, such alteration may be overlooked, given its subtle appearance and distal location relative to veins that mark upflow areas.