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The paper presents the first isotopic U–Pb study data (LA–ICP–MS method) of zircon from intrusive rocks of the Molo-Sarychat pluton situated along the deep-seated fault system of the "Nikolaev Line" in the eastern Kyrgyzstan. The intrusive rocks from this pluton belong to the high-potassic calc-alkaline to shoshonitic series. Intense Mo(–W–Cu–Au) (mainly molybdenum-porphyry) mineralization is spatially and genetically associated with this pluton. Together with the other Au, W and Cu deposits and occurrences, this mineralization is part of the extended metallogenic belt of Tien Shan; however, occurrences of molybdenum-porphyry mineralization are still rare in this belt. The concordant isotopic U–Pb ages of zircon autocrysts indicate the crystallization of quartz monzonite (293.3 ± 4.2 Ma) and monzogranite (286.6 ± 2.4 Ma) in the Early Permian. Zircon antecrysts dated at 306–320 Ma are also present. The crystallization age obtained corresponds to a post-collisional epoch of the development of this territory but the presence of the antecrysts expands the pluton emplacement to the Late Carboniferous-Early Permian, which, as a result, spanned over initially subduction-related and then post-collisional tectonic settings. Correspondingly, a post-collisional setting of the Mo(–W–Cu–Au) (molybdenum-porphyry) mineralization is established; it is related to the pluton studied and was formed after the emplacement of quartz monzonite (early stage) and monzogranite (late stage). Significant enrichment in Mo can be related to its progressing accumulation during magmatic differentiation causing the emplacement of quartz monzonite and especially monzogranite. These processes occurred under the more mature post-collisional tectonic regime, with possible formation of intermediate magma chambers in the Paleoproterozoic metamorphic rocks and ancient granitoids. The age dates determined for rocks from the Molo-Sarychat pluton are similar to those identified for the igneous and metasomatic rocks of the large Kumtor gold deposit that is also associated with the "Nikolaev Line." [ABSTRACT FROM AUTHOR]

The increased attention given to batteries has given rise to apprehensions regarding their availability; they have thus been categorized as essential commodities. Cobalt (Co), copper (Cu), lithium (Li), nickel (Ni), and molybdenum (Mo) are frequently selected as the primary metallic elements in lithium-ion batteries. The principal aim of this study was to develop a computational algorithm that integrates geostatistical methods and machine learning techniques to assess the resources of critical battery elements within a copper porphyry deposit. By employing a hierarchical/stepwise cosimulation methodology, the algorithm detailed in this research paper successfully represents both soft and hard boundaries in the simulation results. The methodology is evaluated using several global and local statistical studies. The findings indicate that the proposed algorithm outperforms the conventional approach in estimating these five elements, specifically when utilizing a stepwise estimation strategy known as cascade modeling. The proposed algorithm is also validated against true values by using a jackknife method, and it is shown that the method is precise and unbiased in the prediction of critical battery elements. [ABSTRACT FROM AUTHOR]

We present coupled textural, elemental, and boron isotopic data of tourmaline from the large Zhunuo–Beimulang collision-related porphyry copper deposits (PCDs) located within the western Gangdese, Tibet. Based on morphology and high-resolution mapping, the tourmaline is classified into three paragenetic generations. The first generation of schorlitic Tur-1 occurs in the monzogranite porphyry as disseminations intergrown with porphyritic K-feldspar and plagioclase. It shows decreasing Fe and Ca and increasing Mg and Al contents from core to rim and has relatively homogeneous δ11B values (− 9.9 to − 8.6‰); low Fe3+/(Fe2+ + Fe3+), Cu, F, H2O, and Sr/Y ratios; and high rare earth elements. These features indicate Tur-1 formed in a low fO2 and metal-poor granitic magma during the pre-mineralization stage. The second generation of porphyritic euhedral Tur-2 is hosted in diorite porphyry enclaves and dikes, where it is intergrown with plagioclase and biotite. It forms part of the schorl-dravite solid solution, with high Fe3+/(Fe2+ + Fe3+), Cu, F, H2O, Sr/Y, and δ11B (− 9.7 to − 5.1‰) values. These features indicate it crystallized from a hydrous, oxidized, metal-, and volatile-rich diorite magma. The third generation of Tur-3 is the most volumetrically important and occurs as veinlets and disseminations in the porphyry, or around Tur-1 and Tur-2. It shows radial and oscillatory zoning and is locally intergrown with chalcopyrite and pyrite within the main mineralization assemblage. It has δ11B values (− 10.5 to − 6.0‰) that overlap with Tur-1 and Tur-2 values. Tur-3 also has variable Fe3+/(Fe2+ + Fe3+), Cu, and volatiles (F and H2O), indicating it crystallized from oxidized to relatively reducing metal- and volatile-rich hydrothermal fluids. Overall, the three generations of tourmaline show a narrow range of δ11B values between − 10.5 and − 5.1‰ that are indicative of a single magmatic source. The high Cu, ferric iron, volatiles, and δ11B values in Tur-2 are interpreted to reflect injection of diorite magma into an open crustal magma storage system that led to the formation of an oxidizing and metal-volatile-rich porphyry system. The three stages of tourmaline formation reflect evolution of the magmatic–hydrothermal system from low fO2 conditions towards more oxidizing, volatile-rich conditions and then a return to more reducing conditions that accompanied Cu precipitation. Overall, the injection of oxidized metal-rich magma into a long-lived magma reservoir is a critical driving force for the development of collision-related PCDs. [ABSTRACT FROM AUTHOR]

The East Qinling Molybdenum Belt (EQMB), which is located on the southern margin of the North China Craton (NCC), is the largest Mo province in the world. This belt hosts a significant number of Mesozoic magmatic-hydrothermal Mo deposits and a small portion of pre-Mesozoic Mo deposits. Understanding the mineralization timing and mechanism of the unique pre-Mesozoic Mo deposits is essential to comprehend the evolution of the EQMB, the pre-Mesozoic Mo enrichment, and the Mesozoic Mo mineralization event. The recently discovered Zhaiwa deposit is a porphyry Mo deposit located in the Xiong'er Terrane of the EQMB. In this study, five molybdenite samples from the Mo-bearing quartz veins were analyzed for Re-Os isotopes composition. These samples yield an isochron age of 1794 ± 45 Ma, which represents the age of mineralization. The mineralization is mostly hosted within the biotite-amphibole plagiogneiss and granite porphyry. LA-ICP-MS U-Pb data of zircons constrain the crystallization age of the granite porphyry to be at 1791 ± 16 Ma. The close spatial and temporal association suggests that the granite porphyry is the causative rocks of the Mo mineralization. The δ34S values of pyrite vary from 5.3 to 6.8‰, suggesting that the S was mainly derived from magmatic source. The intrusion of magmas and associated Mo mineralization are contemporaneous to the regional Xiong'er volcanism that occurred during the late Paleoproterozoic. The Xiong'er volcanism was triggered by partial melting of lithospheric mantle in an extensional setting. The results of our study provide robust evidence for a late Paleoproterozoic Mo metallogenic event along the southern margin of the NCC. Future exploration should also consider the potential of late Paleoproterozoic porphyry Mo mineralization existing in the EQMB, which is closely associated with the Xiong'er volcanism. [ABSTRACT FROM AUTHOR]

Porphyry-type molybdenum deposits, many of which are in China, supply most of the World's molybdenum. Of particular importance are the molybdenum deposits located in the Qinling-Dabie region that are responsible for more than half of China's molybdenum production. A feature that distinguishes this suite of deposits from the better-known Climax and Endako sub-types of porphyry molybdenum deposits is their formation from CO2-rich magmatic-hydrothermal fluids. The role of CO2, if any, in the transport of molybdenum by these fluids, however, is poorly understood. We conducted experiments on the partitioning of molybdenum between H2O-CO2, H2O-NaCl, and H2O-NaCl-CO2 fluids and a felsic melt at 850 °C and 100 and 200 MPa. Here we show that the exsolution of separate (immiscible) brine and vapor leads to the very high brine DMo values needed for efficient extraction of Mo from the magmas forming Dabie-type porphyry molybdenum deposits. Direct exsolution of immiscible CO2 vapour and brine from magma greatly enriches the brine in molybdenum, a likely factor in the genesis of the Dabie-type porphyry deposits that supply much of the World's molybdenum [ABSTRACT FROM AUTHOR]

The evolution of the magmatic-hydrothermal system that formed the Triassic Erdenetiin Ovoo porphyry Cu-Mo deposit, northern Mongolia, is reconstructed through the study of the sequence of stockwork veining and the petrographic characteristics of the veins, as well as the cathodoluminescence and fluid inclusion characteristics of the vein quartz. Early A veins associated with potassic alteration formed at temperatures ≳ 500 °C under lithostatic pressures. The quartz in these veins shows a blue cathodoluminescence emission and is extensively recrystallized. Subhedral to euhedral quartz crystals contained in AB veins precipitated at the ductile to brittle transition at ~ 400–450 °C. The quartz crystals have cores showing a long-lived purple cathodoluminescence color with well-developed growth zoning, whereas the rims of the crystals lack growth banding and have a brownish-red cathodoluminescence emission. Fluid inclusions in the A and AB veins show elevated CO2 concentrations but show no evidence for immiscibility, implying that Erdenetiin Ovoo formed at ≳ 5 km below paleosurface. Quartz in the A and AB veins is crosscut by molybdenite ribbons. The presence of encapsulated molybdenite and sericite grains along growth zones in the quartz rims of the subhedral to euhedral quartz crystals constrains the timing of Mo introduction and suggests an association with the sericite alteration of the host rocks, which affected 50–60% of the deposit. Elevated Cu grades at Erdenetiin Ovoo are linked to the occurrence of C veins, which consist primarily of chalcopyrite and pyrite. These veins surrounded by halos of sericite-chlorite alteration lack quartz as a gangue mineral, suggesting formation at conditions of retrograde quartz solubility at ~ 400 °C and hydrostatic pressures. Late D veins formed at ≲ 375 °C and hydrostatic conditions. The veins consist primarily of pyrite and are associated with texturally destructive sericite alteration of the host rocks. The study demonstrates that hypogene Cu mineralization at Erdenetiin Ovoo was predated and post-dated by sericite alteration, which has important implications to alteration vectoring in porphyry exploration worldwide. [ABSTRACT FROM AUTHOR]

The Kirazlı deposit is located at the center of the Biga Peninsula metallogenic province, in a geological setting characterized by an extensional tectonic environment. A NNW-SSE trending high-sulfidation (HS) orebody with a total reserve of 33.86 Mt @ 0.69 g/t Au and 9.42 g/t Ag lies beneath the Kirazlı Main zone. A porphyry Cu orebody hosted by Eocene intrusive and volcanic rocks has been intersected by drilling within its vicinity. The HS epithermal deposit is hosted by a partly silicified and brecciated Oligocene volcanic and volcaniclastic sequence consisting mainly of basaltic andesite lava flow and lithic/crystal tuff. Lithogeochemistry and zircon U-Pb radiometric ages allow us to distinguish three distinct high-K calc-alkaline magmatic events at ca. 41, 38, and 32 Ma, sourced by metasomatized mantle melts, which have interacted with the crust during their ascent. Porphyry Cu mineralization took place at 36.7 ± 0.4 Ma (muscovite 40Ar/39Ar age) with subsequent re-opening and base metal deposition. Crosscutting quartz-pyrite-molybdenite veins were emplaced at 33.6 ± 0.2 Ma (molybdenite Re-Os age), and followed by the HS epithermal Au-Ag event at ca. 31 Ma, based on a previous study. Our radiometric data indicate that the Kirazlı deposit has recorded a long-lasting Cenozoic magmatic and metallogenic evolution during about 10 Myr. Our study demonstrates that successive, independent, and overprinting, but genetically unrelated, HS epithermal precious metal, hydrothermal Mo, base metal, and porphyry Cu systems have been active at the same location during protracted extensional tectonics of the Biga Peninsula. [ABSTRACT FROM AUTHOR]

The Gangdese belt in Xizang has experienced both Jurassic subduction and Cenozoic continental collision processes, making it a globally renowned region for magmatic rocks and porphyry copper deposits. Numerous Jurassic intrusions have been identified in the belt. Apart from the quartz diorite porphyry in the large Xietongmen deposit, the Cu mineralization potential of other Jurassic intrusions in this belt remains unclear. This study presents zircon U–Pb dating and trace elements, apatite major and trace elements as well as published whole-rock geochemical and isotopic data of the Dongga tonalite in the central part of the Gangdese belt, aiming to reveal the petrogenesis, oxidation state, volatile content, and Cu mineralization potential of this intrusion. The Dongga tonalite has a zircon U–Pb age of 179.4 ± 0.9 Ma. It exhibits high whole-rock V/Sc values (8.76–14.6), relatively low apatite CeN/CeN* ratios (1.04–1.28), elevated zircon (Eu/Eu*)N values (an average of 0.44), high Ce4+/Ce3+ values (205–1896), and high ∆FMQ values (1.3–3.7), collectively suggesting a high magmatic oxygen fugacity. The Dongga tonalite features amphibole phenocrysts, relatively high whole-rock Sr/Y ratios (20.3–58.9), and lower zircon Ti temperatures (502–740 °C), reflecting a high magmatic water content. Estimation of magmatic sulfur content (0.002–0.024 wt%) based on apatite SO3 contents indicates an enriched magma sulfur content. Combined with previous studies and the collected Sr–Nd–Hf isotopes, the Dongga tonalite is derived from juvenile lower crust related with subduction of the NeoTethys oceanic slab. When compared with Xietongmen ore-bearing porphyries, the Dongga tonalite exhibits remarkable similarities with the Xietongmen ore-bearing porphyries in terms of magma source, tectonic background, magmatic redox state, and volatile components, which indicates that the Dongga tonalite has a high porphyry Cu mineralization potential, and therefore, provides important guidance for the future mineralization exploration. [ABSTRACT FROM AUTHOR]

Paleoproterozoic A-type granites are widely distributed in the southern margin of the North China Craton (SNCC), providing important information for understanding the Paleoproterozoic tectonic regimes in this area. This paper reports newly obtained whole-rock compositions and zircon U-Pb ages for the Tieluping syenogranite porphyry (TLP) and Huoshenmiao alkali granite porphyry (HSM) in the SNCC. Zircons from the TLP and HSM have U-Pb ages of 1 805 ± 12 and 1 792 ± 14 Ma, respectively. These ages are taken to date the emplacement of these intrusions. They had high total alkali contents (K2O + Na2O > 7.13 wt.%), with high 10 000 × Ga/Al ratios (3.06–3.41) and Zr + Y + Nb + Ce values (709 ppm–910 ppm) as well as high zircon saturation temperatures (864–970 °C), indicative of A-type granite affinities. High Y/Nb (1.75–3.32), Ce/Nb (7.72–9.72), and Yb/Ta (2.89–5.60) ratios suggested that TLP and HSM belonged to the A2-type granite. The negative whole rock εNd(t) values (−8.4 to −6.6) and negative zircon εHf(t) values (−15.9 to −6.3) confirmed that TLP and HSM were likely generated by the partial melting of an ancient continental crust. The εHf(t) (−7.4 to +4.0) values of inherited zircons in the TLP suggested that they were derived from the partial melting of Archean basement rocks. Considering the geochemical similarity of the 1.80 Ga A-type granitoids in the SNCC, we propose that the TLP and HSM were formed in a post-collisional regime that was likely associated with the break-off of the Paleoproterozoic subducted slab. Upwelling of the asthenosphere provided huge heat to generate the regional 1.80 Ga A-type granite in the SNCC. [ABSTRACT FROM AUTHOR]

Metamorphosed dacitic porphyry dikes were first found in the western part of the Vorontsovka terrane, which is located in the Paleoproterozoic Volga–Don orogen at the margin of Archean Sarmatia and Volga–Ural cratons. The magmatic protolith age for the metadacites is ca. 2.07 Ga. These are ferrous, metaluminous calc-alkali I-type granitoids. The sodium specialization of the rocks and their low concentrations of Mg, Cr, Ni, and incompatible elements, with significant REE fractionation, the absence of Eu* anomalies, high Sr/Y ratio, remarkably high (Gd/Yb)n values (>10), and the radiogenic Nd isotopic composition indicate that the dacitic melts were derived from a juvenile mafic source. According to petrogenetic estimations, such conditions could be caused by the partial melting of depleted N-MORB basites in equilibrium with an eclogitic residue. The dacitic magmas were likely generated by the partial melting of mafic rocks at lower levels of the significantly thickened crust (>60 km) in relation to collision processes. [ABSTRACT FROM AUTHOR]

Delineation of hydrothermal alteration zoning is important for exploration vectoring toward mineralization centers in porphyry systems, and shortwave infrared (SWIR) spectroscopy is widely used to map hydrothermal minerals distribution for porphyry Cu exploration. However, the SWIR method cannot effectively detect anhydrous alteration minerals (e.g., K-feldspar) in the potassic zone. Magnetite can be formed by potassic alteration and destroyed by phyllic (quartz-sericite-pyrite) alteration. The relative intensity of these two alteration types can be quantified by magnetic susceptibility. Here, we integrate the SWIR and magnetic susceptibility measurements to map hydrothermal alteration zones at the Pulang porphyry Cu-Au deposit in northwestern Yunnan, one of the largest porphyry deposits in the SW China-mainland SE Asia region. White mica, chlorite, and montmorillonite + kaolinite were identified in ~ 60%, ~ 30%, and ~ 15% of the analyzed samples from the Pulang deposit, respectively. Volumetric bulk magnetic susceptibility (Kbulk) values are high in the potassic-altered rocks, but low in phyllic-altered rocks. Using white mica as a proxy for sericite alteration, white mica-chlorite assemblage for chlorite-sericite alteration, chlorite-epidote-actinolite assemblage for propylitic alteration, montmorillonite-kaolinite-dickite assemblage for argillic alteration, and Kbulk (> 0.5 × 10–3 SI) for potassic alteration, we delineate the alteration zoning at Pulang. From the causative porphyry center outward, four alteration zones are delineated (potassic → chlorite-sericite → sericite → argillic). The ore-distal propylitic alteration was developed both in the shallow and deeper levels of the hydrothermal system, resembling typical porphyry-style alteration zoning patterns. Our work shows that high Kbulk value is a useful vector toward Cu mineralization at Pulang, whereas illite crystallinity (SWIR-IC), white mica Al–OH spectral absorption peak, and chlorite Fe-OH spectral absorption peak are less effective. We highlight that magnetic susceptibility measurement is an effective alteration-mapping method when mineralization is developed in the potassic zone (with largely aspectral minerals such as quartz, K-feldspar, and magnetite), while SWIR scalars are more useful when mineralization is developed in the phyllic and/or propylitic zones. [ABSTRACT FROM AUTHOR]

Volcaniclastic deposits are cynosures for reconstructing volcanic archives and evaluating the tectonic imprints of the study area. This paper presents an elaborate geological field litholog, petrography and geochemistry of ~1.2 km thick sequence of the quartz-feldspar porphyry (QFP) and rhyolites in the Kadiri–Hindupur section of the Kadiri Greenstone belt from Eastern Dharwar Craton (EDC). The QFP exhibits primary stratification; the thickness of the beds varies from very thin to thick (3–8 cm) and shows large-scale tabular cross-bedding in the lower half of the section. The bedding surfaces of QFPs are marked by current crescent-shaped marks (long axis: 5–25 cm, short axis: 2–8 cm), speculated as possible remnants of volcanic bombs and pyroclastic debris during the explosive volcanism. Petrographically, these QFPs are characterised by spectacular blue opalescent quartz grains with embayed grain boundaries, anhedral feldspar with sieved texture, fractured plagioclase and polycrystalline groundmass suggesting a volcaniclastic origin. They are also endowed with significant post-depositional textures such as domino-listric faulting and sigma-shaped porphyroblasts. Geochemically, QFPs are unaltered with trachyte-trachy dacite compositions showing high-potash, calc-alkaline nature displaying shoschonitic affinity. The primitive mantle normalised trace and rare earth elements are marked by an enriched LREE-LILE pattern coupled by negative zircon–hafnium, niobium–tantalum and titanium anomalies affirming their common genetic link to a prominent island arc–back-arc system where explosive volcanism produced the felsic crystal tuffs that were deposited and preserved as volcaniclastic QFP. The associated blocks and bombs produced the current crescent-shaped marks preserved on the bedding surfaces of QFPs. Research highlights: Research Highlights Quartz-feldspar porphyry (~1.2 km thick) occurs in the Kadiri Greenstone Belt, Eastern Dharwar Craton. Blue opalescent quartz and deformed plagioclase porphyry indicate volcaniclastic origin. Enigmatic current crescent-shaped marks represent remnants of volcanic bombs and pyroclastic debris. The primitive mantle normalised REE diagram is characterised by LREE-LILE enrichment. They represent Neoarchean pyroclastic volcanism and sedimentation in an island arc–back-arc setup. [ABSTRACT FROM AUTHOR]

The genetic link between subduction- and collision-related porphyry Cu deposits (PCD) is still not well understood. The Gangdese porphyry Cu belt (GPCB) in southern Tibet hosts two parallel E–W-oriented metallogenic subbelts, including a southern Jurassic subduction-related and a northern Miocene post-collision PCD subbelt. In this study, we combine new and published whole-rock major and trace element data, Cu isotopic compositions and zircon trace element data of Jurassic magmatic rocks from the GPCB. Combined Sr/Y and La/Yb crustal thickness proxies confirm the south to north geometry of the Jurassic arc-back-arc system across the GPCB. The southern Jurassic magmatic arc rocks have systematically higher whole-rock V/Yb ratios, δ65Cu values and zircon Eu/Eu* ratios compared to those of the northern back-arc region. This suggests that Jurassic southern arc magmas had higher oxygen fugacity and H2O concentration than the contemporaneous northern back-arc magmas, which was controlled by a steep subduction geometry of the Neo-Tethyan oceanic slab. Hydrous and oxidized magmas resulted in Cu enrichment during magma evolution and generation of Jurassic PCD in the southern magmatic arc by inhibiting early sulfide saturation at deep crustal levels. In contrast, the northern back-arc magmas were less oxidized and less hydrous, which triggered early sulfide saturation, resulting in segregation of Cu-bearing sulfides in lower crustal cumulates that provided a favorable metal source for later Miocene PCD in the northern subbelt. Our study indicates that the Jurassic subduction geometry controlled the formation and distribution of Jurassic subduction-related and Miocene post-collision-related PCD in the GPCB. [ABSTRACT FROM AUTHOR]

The Yidun Terrane hosts huge amounts of Late Triassic granitic plutons. While the southern Yidun Terrane, also referred to as the Zhongdian arc, mainly includes Late Triassic porphyry and related porphyry Cu-Au deposits, rare mineralization was found related to the contemporary granitic batholiths in the northern Yidun terrane (NYT). This paper has explored the chemical compositions of the apatite from these intrusions, which provide insights into the petrogenesis and the mineralization potential. The higher Mg and V concentrations and La/Sm ratios of the Zhongdian apatite than the Cuojiaoma and Daocheng apatite in the NYT suggestes that the Zhongdian porphyries were derived from a mixed source with both mantle and crustal contributions, while the Cuojiaoma and Daocheng granites are dominantly crustal derived. Compared with the Cuojiaoma and Daocheng apatite, the Zhongdian apatite are characterized by higher Sr, Eu/Eu* [EuN/(SmN×GdN)0.5], S and Cl, and low Mn and Y concentrations with adakitic affinity, indicating an environment with high oxygen fugacity and S and Cl contents for their parental magmas, which is favorable for the formation of porphyry Cu-Au deposits. By comparing the chemical characteristics of apatite from the ore-bearing porphyries and ore-barren granites in the Yidun Terrane, this study proposes that the apatite from the ore-bearing rocks commonly has relatively high Sr, S and Fe concentrations and low Mn, Y and Si/S ratio. These geochemical characteristics can be good indicators for predicting the metallogenic potential of the rocks. [ABSTRACT FROM AUTHOR]

This paper presents new petrogeochemical data concerning rocks sampled on the Outer Islands in the Gulf of Finland. Earlier, quartz porphyries on Hogland Island were regarded as the standard for volcanic comagmates of rapakivi granites in the Wyborg massif. Sommers Island was found to contain two effusive rock sequences. The "southern" sequence is composed of quartz porphyries whose isotopic age is 1.66 Ga, so they can be regarded as the earliest manifestations of Riphean magmatic activity in the area. The "northern" rock sequence contains, apart from quartz porphyries, also trachybasalts, basaltic andesites, and dacites; the sequence has an isotopic age is 1.59‒1.57 Ga, which is inconsistent with the figures for the adjacent Wyborg massif (1.65‒1.63 Ga). For this reason, in spite of the fact that quartz porphyries and rapakive granites have similar compositions, the volcanics did not result from differentiation of the magma that has produced the granites, but were formed independently of these from a source of the same type which however was in a slightly different structural setting that allowed their free supply onto the ground surface. [ABSTRACT FROM AUTHOR]

The southern margin of the North China Craton (SNCC) contains 8 giant (> 0.5 Mt Mo resources), 4 large (0.1–0.5 Mt Mo resources) and many small (< 0.1 Mt Mo resources) porphyry Mo deposits. Their magmatism ages are concentrated within 150–131 Ma, but it is unclear what determines the size of porphyry Mo systems. Herein, we synthesize new and existing data for the Mo-bearing intrusions in the SNCC to investigate the optimal conditions for giant deposit formation. These intrusions share similar whole-rock geochemistry characteristics and highly differentiated features, with SiO2 and K2O contents ranging from 68.55 to 79.13 wt.% and 2.63 to 11.18 wt.%, respectively. They share similar lower crustal sources with a variable input of mantle materials. Their εNd(t) and εHf(t) values range from -19.1 to -12.7 and -29.5 to -9.3, respectively, and indicate no relationship with metal fertility. The similar ΔFMQ values calculated from zircon geochemistry also suggest that the porphyry Mo deposit size is unrelated to magma redox conditions. High magmatic water contents and high differentiation features (SiO2 > 73 wt.%) exhibit significant positive correlations with the deposit size. Therefore, we propose that magma with a high water content triggered by intensive fractional crystallization is the fundamental requirement to produce large Mo endowment in the SNCC. This conclusion is consistent with the criteria that pulsed release of mineralizing fluids from a large magma chamber through fractional crystallization play an important role in the formation of giant porphyry Mo deposits in other molybdenum belts in the world. [ABSTRACT FROM AUTHOR]

Porphyry copper ore-forming magmas worldwide are chemically distinguished from ordinary arc granitoids by lower Zr and by higher Sr/Zr ratios at equivalent SiO2 contents. Low ppm Zr in zircon-saturated melts and high whole-rock Sr/Zr in granitoid samples retaining igneous plagioclase are useful discriminants of Cu-fertile intrusive complexes. These and other chemical discriminants of porphyry-copper-forming melts of tonalite-granodiorite-adamellite composition cannot develop during crystallisation-differentiation at upper-crustal pressures. They indicate unusually high dissolved H2O (≥ 9 wt%) in residual melts at depths near the base of the crust. We compare Zr behaviour during mafic-to-felsic magmatic differentiation in orogenically deforming, copper-mineralised arc segments with behaviour during differentiation in non-orogenic, unmineralised arc segments laterally adjacent along the same subduction zones. In orogenically deforming segments, horizontal compressive stress provides resistance to opening of tensile dyke fractures and promotes entrapment of mantle-derived basaltic melts in magma chambers embedded in hot country rock at Moho-vicinity depths, where magmas cool slowly and residual melts tend to last long enough to experience intermittent chamber replenishment by basaltic melts from the deeper mantle. Over several cycles of replenishment and fractional crystallisation, residual melts acquire high concentrations of inherited chemical components that were largely excluded from cumulus minerals—H2O, Cl, CO2, SO3, etc. Accumulating H2O re-orders the high-pressure crystallisation sequence of igneous minerals in successive cycles and leads to early and prolific production of hornblende and early zircon saturation in mafic melts (< 60 wt% SiO2) of later cycles and leads to low Zr contents of zircon-saturated intermediate-composition residual melts. [ABSTRACT FROM AUTHOR]

The Urumieh-Dokhtar magmatic arc (UDMA), Iran, hosts giant to small porphyry Cu ± Au deposits associated with Miocene post-collisional magmatism. Previous studies suggested that the ore-bearing suites are derived from chalcophile element-rich juvenile lower crustal igneous rocks, and that metal contents in the magmas play an important role in the formation of porphyry Cu ± Au deposits in this region. This study investigates the whole-rock major, trace, and platinum group element (PGE) geochemistry, as well as zircon trace element geochemistry, of six porphyry Cu ± Au ore-bearing suites and three barren suites in the central and southeastern UDMA. The aim is to revisit their petrogenesis and understand the factors controlling the formation of post-collisional porphyry Cu ± Au deposits. The high Mg# and Cr and Ni contents of the most mafic variants of ore-bearing and barren rocks suggest that they are primarily derived from the mantle. However, the ore-bearing magmas from the small Dalli Cu–Au porphyry and barren magmas from central to southeastern UDMA experienced substantial crustal assimilation during evolution. The evolved ore-bearing magmas exhibit high La/Yb and Sr/Y ratios, along with concave upward chondrite-normalized REE patterns and high zircon Ce/Nd and Eu/Eu* values, suggesting that they have undergone amphibole dominant differentiation under hydrous and oxidized conditions. In contrast, the barren magmas are characterized by lower whole-rock La/Yb and Sr/Y and zircon Ce/Nd and Eu/Eu* values with flatter REE patterns, implying plagioclase dominant differentiation. The ore-bearing suites, except for the Dalli suite, have systematically higher Pd and Pt contents than barren suites with highly fractionated PGE patterns (high Pd/Ir). The chalcophile element fertility of the ore-bearing suites, as indicated by high Pd/MgO and Pd/Pt ratios, is comparable to that observed in porphyry Cu deposits found elsewhere. This similarity suggests that the Cu contents of the magma likely played acrucial role in the formation of the porphyry Cu deposits in the central and southeastern UDMA. Late sulfide saturation or small amounts of sulfide segregation may have led to the high Cu and moderate Pd contents of the ore-bearing magmas until the late stage of differentiation. In contrast, early sulfide saturation resulted in significant depletion in all PGE and Cu in the barren magma. The fractionated PGE patterns of the ore-bearing magmas could have arisen due to two potential processes. Firstly, they may have resulted from fractional crystallization of Cr-spinel in the early sulfide undersaturated differentiation. Secondly, the patterns might have been inherited from partial melting of metasomatized lithospheric mantle. The systematic geochemical differences between ore-bearing and barren suites suggest that the more hydrous and oxidized nature and higher Cu contents of the ore-bearing magmas substantially increase the porphyry Cu ore potential in the central and southeastern UDMA. [ABSTRACT FROM AUTHOR]

The results of petro- and paleomagnetic studies of phase-I gabbrodiorites from the Lower Amur Complex of the Zhuravlevka-Amur terrane (Poni massif, Poni-Mulinsky ore cluster) are presented. They were used to determine that during the formation of the Lower Amur intrusive complex (Cenomanian-Turonian) the Amur River zone was located approximately 10° north of its current position between the Central Sikhote-Alin fault in the east and the Priamursky fault in the west. It is shown that starting from the middle of the Cenomanian there were no latitudinal movements of the Amur River zone of the Zhuravlevka-Amur terrane relative to the Eurasian continent. However, a more than 20°-counterclockwise rotation of the zone relative to the continent was recorded, which is easily explained within the ball-bearing tectonic model under the impact of the Amur and Central Sikhote-Alin en echelon left-lateral strike-slip faults. The left-lateral strike-slip fault systems were likely to be the channels for mantle material supply during the formation of the largest Malmyzh porphyry copper deposit, which, along with the Poni-Mulinsky ore cluster, is part of the Lower Amur mineragenic zone. [ABSTRACT FROM AUTHOR]

Although porphyry systems like metallo-phthalocynine are recognized as promising molecular models for electrocatalytic oxygen reduction reaction (ORR), their poor durability and methanol tolerance are still challenges and need improvement before being considered for practical applications. Herein, we successfully designed and constructed a Fe-phthalocyanine-derived highly conjugated 2D covalent organic framework (2D FePc-COF), using octa-amino-Fe-phthalocyanine (OA-FePc) and cyclohexanone as precursors. The prepared 2D FePc-COF was characterized via multiple analytic techniques. The electrochemical studies indicated that prepared 2D FePc-COF was far more superior to OA-FePc and 20% Pt/C, displaying anodic shift of 100 and 50 mV (vs RHE) in formal potential, respectively. Moreover, this catalyst also demonstrated excellent methanol tolerance and durability (over 10,000 CV cycles). Theoretical investigations revealed that due to extended conjugation and elimination of electron donating groups (-NH2), the shifting of dz2-orbital (Fe) energy took nearer to π*-orbital (O2), allowing optimum coupling of both the orbitals, thereby enhancing 4e− ORR. This work demonstrates the art of molecular design, aiming at improving catalytic activity of macrocyclic molecular systems towards ORR. [ABSTRACT FROM AUTHOR]

The Kighal porphyry Cu deposit, in the Arasbaran magmatic belt (AMB), is hosted by Late Eocene to Oligocene volcanic rocks and Miocene high–K calc–alkaline subvolcanic intrusions. The Miocene quartz monzonite stocks host porphyry–style Cu mineralization characterized by potassic, phyllic, argillic, and propylitic alteration zones and an advanced argillic lithocap. The Ar–Ar dating of secondary biotite from the potassic alteration and alunite from the lithocap yields precise ages of 20.10 ± 0.18 Ma and 19.15 ± 0.21 Ma, respectively, documenting the evolution of the hydrothermal system over ~ 1 Myr. Hydrothermal rutile occurs in the deposit from the proximal potassic to distal propylitic alteration zones, and their Ti–Fe–Cr–V–W contents can be used as a fertility indicator which suggests a decrease from the proximal zones towards the distal zones. The geochemical fingerprints of the Kighal (and in general the AMB) igneous rocks reflect a post–collisional arc setting. Their distinctly high Th/Yb and Ta/Yb ratios are typical of high–K calc–alkaline intrusions, suggesting that their parental melts were derived from an enriched upper mantle source modified by slab–derived components. Their 87Sr/86Sr(i) (0.70427 to 0.70452) and 143Nd/144Nd(i) (0.512712 to 0.512754) ratios reveal that the magmas experienced moderate crustal assimilation during their magmatic evolution, also supported by increasing Th/La and 87Sr/86Sr(i) and decreasing εNd(i) values with increasing SiO2 content. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the intrusions (18.67 to 18.84, 15.60 to 15.66, and 38.83 to 39.06, respectively) reveal a crustal origin. Hence, a post–collisional arc setting is proposed for NW Iran, in which mantle–derived mafic melts underwent a MASH process and ascended into shallow magma chambers in the upper crust associated with moderate crustal contamination, which account for the formation of large–scale porphyry Cu mineralization in the AMB. [ABSTRACT FROM AUTHOR]

Oxygen fugacity (fO2) is a critical factor that controls the formation mechanisms of the porphyry Cu deposits. However, the differentiation of the fO2 in post-collisional Au-mineralized and Cu-mineralized porphyry intrusions remains unclear. The post-collisional Jinshajiang–Ailaoshan metallogenic belt hosts several Eocene Cu–Au–Mo porphyry systems including the Yulong Cu, Machangqing Cu, Chang'anchong Cu, and Beiya Au deposits and contains several barren porphyry intrusions, such as the Jianchuan, Putaishan, and Bailiancun granite porphyries. This study compares the zircon chemistry, magmatic fO2, and petrogenesis among the Cu-mineralized, Au-mineralized, and ore-barren porphyries. Our results show that the fO2 of the Cu- and Au-porphyry systems (average ΔFMQ = + 1.59 ± 0.77) is higher than that of the ore-barren (average ΔFMQ = − 0.43 ± 0.91) granite porphyry. Notably, compared to the Au-mineralized porphyries (average ΔFMQ = + 0.99 ± 0.70), the Cu-mineralized porphyries crystallized from more oxidized magma (average ΔFMQ = + 1.89 ± 0.60). All the Cu-mineralized, Au-mineralized, and ore-barren porphyry intrusions originated from partial melting of a thickened lower crust with minor input from the enriched lithospheric mantle-derived melts. The lithosphere of the Au-mineralized and ore-barren porphyry intrusions was influenced mainly by the slab-derived fluids, whereas the lithosphere of the Cu-mineralized porphyry intrusions was metasomatized by slab-derived melts. Therefore, we propose that the parental magmas for the Cu–mineralized porphyry possibly inherited the high oxidation state of the slab-derived melts and then contributed to the high fO2 of the Cu-mineralized granite porphyries. Collectively, the magmatic processes at deep levels played an essential role in determining the fO2 of the granite porphyry, thus controlling the mineralization diversity. [ABSTRACT FROM AUTHOR]

Whole-rock geochemical signals of porphyry intrusions can provide clues for key metallogenetic processes and the potential for porphyry Cu deposits (PCDs). However, it cannot be guaranteed that these signals are the best choices, because they are proposed more based on the individual experience of researchers or some local and limited research data. In this study, it was found that the fertility potential for contemporaneous porphyry intrusions from different locations (fertility field) could be identified according to the composition statistics of the porphyry intrusions in the southern Sanjiang Tethyan Orogen. Therefore, a crucial signal-ranking Monte Carlo-based framework was implemented using the feature importance acquired from a random forest machine learning method. The first six crucial variables among 31 oxides and elements for fertile magma identification were then grouped into three sets using principal component analysis and hierarchical cluster analysis. Several optimal two-dimensional discrimination plots were built based on the k-nearest neighbor classification method according to the three sets of oxides and elements. The results indicate that the fertile magmas have signatures of high Sr, Ba, and P2O5 and low heavy rare earth elements (REEs) and SiO2. These signatures indicate that hydrous, oxidized, and volatile-rich Cu-fertile magmas originated from a thick arc crustal environment and underwent amphibole and garnet fractionation in the deep crust and the subsequent addition of mafic melt in shallow chambers. The application of these discrimination plots in the Paleo-Tethyan shows that the Zhongdian Triassic–Jurassic PCDs that developed in the sub-Paleo-Tethyan subduction zones are special cases. [ABSTRACT FROM AUTHOR]

Large volume, intermediate-felsic magma reservoirs are the source of melt and mineralising fluids which generate porphyry copper deposits. Cooling and crystallisation of hydrous magmas drives the exsolution and expulsion of a magmatic volatile phase—a process which remains challenging to constrain in porphyry Cu systems where the record of magma volatile compositions is rarely preserved. Here, we use the halogen compositions of apatite inclusions shielded as inclusions within zircon to constrain volatile evolution in magma reservoirs which pre-date and are synchronous with porphyry Cu mineralisation at Quellaveco, Southern Peru. Geochemical and textural data confirm that the zircon-included apatites escaped re-equilibration with hydrothermal fluids, unlike apatites found in the groundmass of the same rocks. We, therefore, recommend that future studies attempting to reconcile magmatic volatile budgets using apatite in porphyry Cu systems should focus on apatite inclusions in zircon. By combining the apatite inclusion data with numerical modelling, we find evidence that the magma reservoir sourcing porphyry Cu mineralisation remained fluid-saturated for the entire period recorded by apatite crystallisation. By contrast, the pre-mineralisation batholith shows more variable, potentially fluid-undersaturated behaviour. Our modelling suggests that in order to attain the porphyry melt volatile compositions inferred from apatite, the magma reservoir must have exsolved a large proportion of its volatile budget, consistent with having been held at high crystallinity (40–60% crystals). This crystallisation interval coincides with peak chlorine and copper extraction from intermediate-felsic magmas, and would have permitted efficient fluid migration and accumulation at the roof of the system. We suggest that the storage of large-volume, long-lived, crystal-rich magma reservoirs in magmatic arcs may be a critical step in generating world-class porphyry copper deposits. [ABSTRACT FROM AUTHOR]

The Yangchuling porphyry W–Mo deposit is an oxidized tungsten deposit in the Jiangnan tungsten belt, which is the largest tungsten belt in the world. Both W- and Mo-mineralization predominantly occur in the cupola of a monzogranite porphyry with abundant mafic dikes and microgranular mafic enclaves (MMEs). Acicular apatite in MMEs and similar SIMS U–Pb zircon ages of the monzogranite porphyry (149.7 ± 1.1 Ma) and MMEs (148.7 ± 1.3 Ma) suggesting mixing of mafic and felsic melts. Plagioclase phenocrysts are oscillatory zoned with An-rich and An-poor zones with lower 87Sr/86Srinitial values and higher contents of Mg, Ti, and Sr in the An-rich zones and resorption surfaces in An-poor bands. These textures reflect multiple injection of mafic magma into the magma system responsible for the formation of the Yangchuling deposit. Whole rock Sr–Nd isotope data and zircon Hf–O isotope data indicate 60–70% contribution from the enriched mantle and 30–40% from the crust to the ore-forming granitic rocks. The W and Mo endowments of the Yangchuling deposit and other W-Mo deposits in the Jiangnan tungsten belt have different sources. Whereas W is derived from the melting of supracrustal metasedimentary rocks, Mo is contributed by mafic magmas. The latter is inferred from (i) the close relationship of Mo mineralization with mafic dikes and MMEs rather than the more evolved monzogranite porphyry and (ii) higher Mo concentrations in scheelite from MMEs (3020–3406 ppm) than in scheelite from the host monzogranitic porphyry (540–1886 ppm). On the scale of the whole Jiangnan tungsten belt, granitic rocks with more intense Mo mineralization have higher εHf zircon values that demonstrate higher input of mantle material to the deposit-forming granites. [ABSTRACT FROM AUTHOR]

The Wangjiadashan area in Suizhou-Zaoyang region of Hubei Province in the Tongbai-Dabie orogenic belt hosts important copper-gold deposits and contains a large number of quartz syenite porphyry dykes, occurring mostly along the NEE-trend faults. In this study, we used LA-ICP-MS zircon U-Pb dating method and obtained an age of 143.6 ± 1.4 Ma, which represents the emplacement of these quartz syenite porphyry dykes was at the Yanshanian, but it was slightly earlier than the previously reported ages (139–135 Ma) for granites widespreading in Suizao area. The geochemical data of the Wangjiadashan quartz syenite porphyry show high K2O, CaO, Na2O and Al2O3 contents but extremely low MgO contents (0.01 wt.%–0.46 wt.%). The geochemical characteristics indicate that these quartz syenite porphyry dykes belong to the typical C-type adakite and were possibly formed in the post-collisional environment. Multi-isotopic (Sr-Nd-Pb-Hf) analyses indicate that these quartz syenite porphyry dykes were originated from crust without distinct mantle materials involved. It is suggested that the Wangjiadashan quartz syenite porphyry was generated from partial melting of the thickened lower continental crust, and garnet but no plagioclase was left as residual phase. Compared with the widespread granites of the Tongbai area, the Wangjiadashan quartz syenite porphyry formed earlier and derived from more juvenile and K-rich lower crust, while they all belong to intensive magmatism concentrated during the Early Cretaceous epoch in the Tongbai area. [ABSTRACT FROM AUTHOR]

This comprehensive research has been conducted to consider the distribution of PTEs in the surface sediments of a recently developed Dar-e-Allo copper mine in dependence on the potential ecological and human health risks. Field sampling was carried out discreetly at preselected sampling spots including the natural background, the streams around the mine, waste rock drainages, evaporative deposits, sediments containing Fe oxy-hydroxides and secondary phases. Distribution of target elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Se, and Zn) showed high levels of crustal elements. As regards, Fe, Al, and S are identified to exist as the most copious elements in the earth's crust, so have the major portion of potentially toxic elements (PTEs) in the sediment concentrations. Evaluating environmental indices reflected that in general, Cu, S, and Mo have a higher quota of contamination in sedimentary systems. the pollution load index (PLI), modified contamination degree (mCd), Contamination factor (Cf), Sediment potential index (SPI), Geo-accumulation index (Igeo) and Contamination degree (Cd) confirm that sedimentary systems of mining area are heavily contaminated by PTEs and were not found within the guideline acceptable values. The potential ecological risk index (PERI) displayed a high or severe risk level for Cu with a peak in green–blue sediments containing secondary minerals. The results of total carcinogenic risk (TCRs) show that As has high toxicity level and carries a risk of carcinogenicity among children and adults. The TCRs for Cd, Cr, Ni, and Pb with carcinogenic potential are found only in children and they are classified as the prime concern elements that have serious dangers to children's public health. The results of contamination source presumed that the sources of PTEs contamination were principally geogenic along with the anthropogenic sources in the study area. Therefore, the present study has highlighted the implication of human health risks of PTEs in sedimentary systems of copper mining, also will grant advice for prime stakeholders, including mine managers, Environmental Protection Agency, the government and public organizations in connection to protecting the environment, aquatic biota and consumer's health. [ABSTRACT FROM AUTHOR]

An essential part of the world's remaining mineral resources is expected to reside deep in the crust or under post-mineralization cover. For porphyry copper deposits, the world's primary source of Cu, Mo, and Re, identifying the dynamic processes that control their emplacement in the upper crust can guide future exploration. Seismic tomography can constrain these processes through imaging deep-seated structures at the regional scale. Here we construct a three-dimensional model of the Vp/Vs ratio, based on arrival times of P and S seismic waves, beneath the Cerro Colorado porphyry Cu–(Mo) deposit in northern Chile. Our images show that low Vp/Vs (~ 1.55–1.65) anomalies, extending to ~ 5–15 km depth, coincide with the surface expression of known porphyry copper deposits and prospects, as well as delimit structures that host orebodies and related hydrothermal alteration zones. Medium Vp/Vs (~ 1.68–1.74) and high Vp/Vs (Vp/Vs ~ 1.85) bodies correspond to intermediate-felsic plutonic precursors for porphyry intrusions and mafic magma reservoirs that underlie shallower orebodies, respectively. Imaging these precursor and parental plutons is crucial to the identification of orebodies as they act as the source of fluids for porphyry copper generation. This study demonstrates the potential of local earthquake tomography as a tool to identify future deep mineral resources with minimal environmental impact. [ABSTRACT FROM AUTHOR]

The Dexing porphyry deposit is the largest porphyry Cu–Mo–Au deposit in South China. Biotite composition can record the physicochemical conditions and evolution history of magmatic-hydrothermal system. Biotite from the Dexing porphyry deposit could be divided to three types: primary magmatic biotite (Bi-M), hydrothermal altered magmatic biotite (Bi-A) and hydrothermal biotite (Bi-H). The temperature of Bi-M and Bi-H range from 719 to 767 °C and 690 to 727 °C, respectively. Both magmatic and hydrothermal biotite have high Fe3+/Fe2+ ratios (from 0.18 to 0.24) and XMg values (from 0.57 to 0.66), indicating a high oxygen fugacity. Bi-M has F lower than Bi-A and Bi-H (up to 0.26 wt%), but has Cl (Cl = 0.18–0.30 wt%) similar to Bi-A and Bi-H (Cl = 0.21–0.35 wt%), suggesting that high Cl/F ratios of early hydrothermal fluid may result from the exsolution from high Cl magma. From potassic alteration zone to phyllic and propylitic alteration zones, Cl decreases with increasing Cu, whereas F increases roughly. Therefore, Cl mostly originate from magma, but enrichment of F possibly results from reaction of fluids and Neoproterozoic strata. Negative correlation between Cl and Cu indicates that Cl might act as an important catalyst during Cu mineralization process. Biotite from Dexing has similar halogen compositions to other porphyry Cu-/Mo deposits in the world. Chlorine contents of hydrothermal fluid may be critical for Cu transportation and enrichment, while consumption of Cl would promote Cu deposition. [ABSTRACT FROM AUTHOR]

Obtaining spatial correlation between estimated physical parameters and corresponding lithological features is always challenging in geophysical exploration. This research provides various estimated geophysical models at two porphyry centers in the Dalli Cu–Au deposit in central Iran to characterize hydrothermal alteration zones, host lithologies, and mineralization. The dataset used in this research consists of ground magnetic and direct current electrical resistivity and induced polarization data and core drilling geochemical analyses. Constraints such as appropriate depth weighting via calculation of the power spectrum and Euler deconvolution of the magnetic data were used to relieve the non-uniqueness nature of magnetic data inversion. The resulting estimated models from 3D inversion of magnetic data to 2D inversion of direct current electrical resistivity and induced polarization data inversion indicated that higher chargeability zones and strong copper and Au mineralization zones are spatially associated with a significant modulus of magnetic susceptibility gradient. The models also confirm the presence of a U-shape pyrite shell at the Dalli porphyry deposit. Overlaying the geochemical drilling data on this shell showed that the inner boundaries correspond well with the zones of significant Cu–Au mineralization. Comparing the geophysical models with the host lithologies indicated that the inner part of the primary quartz diorite porphyry as the host rock dominantly has potassic alteration, with lower Cu–Au grades, higher magnetic susceptibility, and lower resistivity. In contrast, the main Cu–Au mineralization concentration occurs between the quartz diorite intrusion and the pyrite shell that is located mainly in the wall rock andesite porphyries, where magnetic susceptibility is decreased. [ABSTRACT FROM AUTHOR]

The world's largest current Cu resource is volcanic arc-hosted, porphyry copper deposits. Whether unusual parental magmas or fortuitous combinations of processes accompanying emplacement of common parental arc magmas (e.g., basalt) is required for ore deposit formation, remains unclear. Spatial and tectonic associations of adakite (andesite with high La/Yb, Sr/Y) with porphyries exist, but genetic links are debated. Delayed saturation with Cu-bearing sulfides consequent to elevated redox state seems essential for late-stage exsolution of Cu-bearing hydrothermal fluids. Partial melting of igneous layers of subducted, hydrothermally altered oceanic crust in the eclogite stability field are invoked to account for andesitic compositions, residual garnet signatures, and the putative oxidised character of adakites. Alternative petrogeneses include partial melting of lower crustal, garnet-bearing sources and extensive intra-crustal amphibole fractionation. Here we demonstrate mineral-hosted, adakite glass (formerly melt) inclusions in lavas erupted subaqueously in the New Hebrides arc are oxidised relative to island arc (and mid-ocean ridge) basalts, are H2O-S-Cl-rich, and moderately enriched in Cu. Polynomial fitting of chondrite-normalised, rare earth element abundance patterns shows the precursors of these erupted adakites were unequivocally derived from partial melting of subducted slab, and represent optimal porphyry copper progenitors. [ABSTRACT FROM AUTHOR]

Most porphyry Cu deposits are formed in magmatic arc settings, but some occur in non-arc environments, such as intracontinental settings. The petrogenesis of fertile magmas for porphyry Cu deposits formed in intracontinental settings is still ambiguous. To address this issue, we performed an integrated study of the late Mesozoic porphyry Cu deposits in the South Qinling Orogenic Belt. Zircon U–Pb ages indicate that these late Mesozoic porphyry Cu deposits were formed at 149–142 Ma, in a postcollisional intracontinental setting. εNd(t) (− 4.5 to − 2.7), initial 87Sr/86Sr (0.7046 to 0.7084), and zircon εHf(t) values (− 3.8 to + 2.2) of the late Mesozoic ore-forming and barren rocks suggest that both originate from Meso-Neoproterozoic juvenile lower crust. Whole-rock geochemical and isotopic characteristics indicate that the ore-forming rocks could be formed by the delamination of thickened juvenile lower crust or by the reaction of mantle with normal juvenile lower crust. The barren rocks could be formed by the partial melting of thickened or normal juvenile lower crust. Whole-rock petrochemistry and reversed anorthite contents and Sr isotope data of zoned plagioclase crystals indicate that the mafic magma was recharged into the ore-forming magma chamber. Due to the injection of mafic magma, the ore-forming rocks obtained higher oxygen fugacity, volatiles, water, sulfur, and Cu contents than the barren rocks. According to the regional tectonic evolution, the late Mesozoic porphyry Cu deposits in the South Qinling Orogenic Belt were formed in an extensional environment due to transformation of the tectonic regime. Large-scale lithospheric extension caused asthenospheric mantle upwelling and crust-mantle interaction, providing the crucial metallogenic conditions. Moreover, the injection of mantle-derived mafic magma into the normal magma is a key factor in the formation of the late Mesozoic porphyry Cu deposits in the SQB and similar porphyry systems in an intracontinental setting. [ABSTRACT FROM AUTHOR]

The Wulong gold deposit (> 80 t Au) is located at the northeastern margin of the North China Craton (NCC). Gold in the most economically important quartz veins (Stages 2 and 3) is associated with a varied assemblage of Bi and Te minerals. Stage 2 is characterized by, in a temporal order, native gold-native bismuth-maldonite-hedleyite, bismuthinite-Bi-sulfotellurides, electrum-hessite-Bi-Pb-Ag sulfosalts, Bi-Pb sulfosalts, and Bi-Pb-sulfotellurides. All of these minerals except maldonite, electrum, hessite, and Bi-sulfosalts are present in Stage 3 veins, which also contain jonassonite and unnamed minerals with stoichiometry of Bi8Te3 and Bi5Te3. These complex Bi mineral assemblages resulted from changes in Pb, Ag, Te and Bi concentrations in reduced hydrothermal fluids both locally and temporally, from Stage 2 to 3. Texturally, approximately 85% of the gold grains are associated with almost all Bi minerals in each main-stage mineralization. Quartz-vein ores from Stages 2 and 3 have high Bi concentrations (up to 7332 ppm) and show a positive correlation between Bi and Au, with Bi/Au ratios > 10. These textural and geochemical associations, together with the occurrence of numerous droplet-like blebs and small inclusion trails of native bismuth and Bi-tellurides with native gold, maldonite, or jonassonite, suggest that Bi-rich melts may have formed from the hydrothermal fluids of Stages 2 and 3, and acted as an Au scavenger in a complex Bi-Au-Pb-Ag-Te system. Hence, the intimate association of Bi and Au at Wulong is the result of Au enrichment via the liquid bismuth collector mechanism. Unlike Wulong, however, other deposits in the NCC, such as Yangzhaiyu (Xiaoqinling district), Guilaizhuang (Jiaodong district) and Dongping (Jidong district), are characterized by low Bi concentrations, and are much richer in Te than Bi, so these systems could not generate low-melting point Bi-rich polymetallic melts. The low-sulfur Bi-Au-Pb-Ag-Te association at Wulong is consistent with that observed in reduced intrusion-related gold systems elsewhere and suggests that hydrothermal fluids may have been derived from the co-located Early Cretaceous diorite-granite porphyry dyke swarm. [ABSTRACT FROM AUTHOR]

Magmatic sources of porphyry deposits in postcollisional settings remain controversial. We have used new and published petrological and geochemical data for the Eocene–Oligocene porphyry Cu ± Mo ± Au deposits in the Sanjiang region, SW China, to address this outstanding issue. New data for three deposits (Machangqing, Tongchang, and Beiya) in the Ailaoshan–Red River porphyry Au-Cu-Mo belt (southern part of the Sanjiang region) suggest that ore-forming porphyries were emplaced at ~ 35 Ma, have high (87Sr/86Sr)i (0.7068–0.7071) and negative εNd(t) (− 6.9 to − 5.0), low zircon εHf(t) (− 5.3 to 4.5), and relatively high δ18O (5.9–9.0‰). Magmatic amphibole phenocryst compositions indicate that the parental magmas are all relatively oxidized (ΔFMQ = 1.7 ± 0.6), and H2O-rich (3.8 ± 0.3 wt% H2O). These results are consistent with those estimated from zircon compositions (ΔFMQ = 1.8 ± 0.8) and high whole-rock Sr/Y ratios (75 ± 31), respectively. Based on the new and published data, we suggest that the parental magmas for the Ailaoshan–Red River porphyry Au-Cu-Mo belt were derived from a preserved juvenile arc lower-crust and the underlying metasomatized subcontinental lithospheric mantle (SCLM) attributed to a Neoproterozoic subduction event, whereas the parental magmas for the Yulong porphyry Cu-Mo belt (northern part of the Sanjiang region) originated from the Permian–Triassic juvenile arc lower-crust and metasomatized SCLM. Additionally, parental magmas for these porphyry deposits are all oxidized and H2O-rich, and we attribute such characteristics to inheritance from mixed mantle-crust sources that were modified by previous oceanic slab subduction. [ABSTRACT FROM AUTHOR]

Delimiting mineralization targets executing various exploratory data is a challenging issue especially in deposit scale studies. Deposit scale studies need reliable mineral potential map (MPM) as drilling guidance which be contained all mineralization zones with the least errors. This scope is not feasible by applying an integration method alone. Furthermore, applying more than one integration method and using some MPM separately will be confusing and cannot be eventuated to a successful drilling in mineral exploration. Therefore, integrating some reliable MPMs with presenting uncertainty map (hybrid technique) is the best procedure which has high confidence level for exploration of a mineralization deposit. In this regard, exploratory data comprising geochemical and geological evidence layers were integrated using well-known integration methods such as the technique for order preference by similarity to ideal solution (TOPSIS) and VIKOR. Then, their MPMs were incorporated employing evidential belief functions (EBFs) method which can produce quadruplet maps and even clear uncertainty degree. The proposed hybrid approach was evaluated through P-A plots and field checking for confirming its power and accuracy in detecting mineralization outcrops from Zafarqand porphyry Cu-Mo deposit which is located in the central region of the Urumieh-Dokhtar Volcanic Arc (UDVA) in Iran. [ABSTRACT FROM AUTHOR]

The controversial topic of genetic relationships of shallow magmatogenic ore deposits with associated complexes of small intrusive bodies or separate syn-ore bodies is discussed in this article. Materials of the field study by the authors of four epithermal gold deposits of the Amur region are used. These materials are supplemented by an analysis of published data on the conditions and geological settings of the localization of a number of other epithermal and shallow Cu-Mo-porphyry deposits in various regions of Russia and other countries. The active thermal participation signs of syn-ore stocks and sill in retraction to intrusions and initiation of near-intrusive convection of deep-seated fluids during ore formation at epithermal gold deposits of the Amur region (Pokrovskoe, Pioner, Zheltunak, Bamskoe, and Mnogovershinnoe) have been established and confirmed by model experiments. These signs and zoning of metal deposition are also established at epithermal and porphyry deposits in other regions of Russia (Ural, Transbaikalia, and Kamchatka) and in other countries. Favorable conditions for ore accumulations have been identified. These conditions are associated with shallow syn-ore small intrusions and magma chambers at 11 characteristic deposits, including large and unique ones (Pioner, Mnogovershinnoe, Bingham, and Klaimax). [ABSTRACT FROM AUTHOR]

Trace elements in quartz reflect the physio-chemical conditions of growth of the mineral and are also capable of tracing the evolution history of the associated ore-forming fluid, and are therefore a potential discrimination signature for different styles of ore genesis. In this study, we compile data on quartz trace elements from 25 porphyry, pegmatitic, greisen, skarn, epithermal, Carlin and Mississippi Valley type (MVT) deposits. Trace elements that relate to the Si4+ substitution types and precipitation conditions of quartz, such as Li, Al, Na, P, K, Ti, Fe and Ge, have been chosen to plot different geochemical diagrams. The quartz Ti vs. Al/Ti, Al vs. Al/Ti and Ti–10Ge–Al/50 diagrams reveal the evolution of the hydrothermal fluids in different types of ore deposits. The results confirm that Ti4+ incorporation into quartz is generally related to temperature variation, whereas Al3+ incorporation is more likely controlled by pH fluctuation. The trace element compositions of quartz from porphyry, greisen, pegmatitic, skarn, epithermal, Carlin and MVT deposits are distributed along a C-shape curve in the Ti–10Ge–Al/50 diagram, which is consistent with temperature decrease. In addition, there are different independent partitions in the Ti–P–Na geochemical source discrimination diagrams, which potentially discriminate the quartz from porphyry, pegmatitic, greisen, skarn, epithermal and Carlin type of deposits. This study shows that quartz trace elements can be used as a useful proxy for tracing the evolution of the hydrothermal fluids in different types of ore deposits and are also a useful auxiliary tool to discriminate different modes of ore genesis. [ABSTRACT FROM AUTHOR]

The chemical compositions of zircons have been used as magma fertility indicators for porphyry copper mineralization potential. Here, we trained and tested two machine learning (ML) models: support vector machines and random forest to classify the metallogenic fertility (fertile vs. unfertile) based on igneous zircon chemistry. Both models achieved good classification accuracy (~ 93%) against the testing dataset, suggesting the feasibility and effectiveness of using the ML methods to discriminate whether zircons are from fertile or unfertile magmas. The feature importance analysis of the RF classifiers identified that the most important parameters of fertile magma are Eu, Ce, and Dy, further validating previous studies of the genesis of porphyry copper deposit-related magma. As a case study, we predicted the metallogenic fertility of the detrital zircons in the eastern Gangdese belt in southern Tibet by applying the ML models trained by igneous zircon labeled data. Our ML models suggest that the magmas that formed after 50 Ma, especially from 30 to 10 Ma, have higher fertile percentages. Taking this together with the local singularity analysis of detrital zircon U–Pb ages, we suggest that magmatic flare-ups with high FP and singularity index values are more favorable for porphyry copper formation. Our ML models and defined FP may help reveal temporal variation of the favorability for porphyry copper formation. [ABSTRACT FROM AUTHOR]

Incorrect estimation of grade values is a major problem in the Sungun copper mine of Iran that the kriging estimates and blast hole data show inconsistencies due to biased estimates of kriging in this case. Therefore, re-evaluation of mineable reserve of the Sungun mine was considered through spatial copula because of its advantages over kriging. Spatial dependence of variable under study was analyzed through the calculation of empirical copulas and variograms. A Jackknife test was implemented by dividing the observed values into data and validation sets. Validation sets were estimated through Archimedean copulas and ordinary kriging methods, and the estimated values were compared to the real ones. Copula showed better accuracy and precision than ordinary kriging due to better reproduction of mean values and having lower mean square errors. Moreover, cumulative distribution functions of the copula estimates were closer to those of observations. Ordinary kriging showed biased estimates, especially for highly skewed data with extreme values. The copula method showed higher local precision due to having smaller estimation errors. Based on the estimated values and their confidence intervals, the blocks were classified as A, B, C1, C2, and C3 categories. The copula method showed its superiority over ordinary kriging by giving higher number of blocks categorized as A and B. Moreover, the average Cu value of the mineable blocks, which is 0.62% in the blast hole data, was respectively calculated through copula and ordinary kriging to be 0.69% and 0.88%. [ABSTRACT FROM AUTHOR]

This study was planned with the aim of identifying the nature and circumstances of the high-graded central core and increasing trend of copper content through depth of 1000 m in Miduk PCD. Mechanisms of high-grading, refer to hypogene enrichment (HE), in PCDs poorly understood. Two main hypotheses for hypogene enrichment formation assumed addition of extra copper to the system, alternatively hypogene leaching and enrichment. In order to obtain alteration-mineralization-geochemical pattern both horizontally and vertically, all macroscopic data extracted from relogging of 6800 m' drill core along an east–west profile, compiled with microscopic observations from studying of 550 thin-polished sections and copper grades of 3400 samples analyzed by XRF and ICP-OES. Our findings proved hypogene enrichment events at deposit. HE evidences in macroscopic and microscopic scales identified almost as various replacement textures between Fe-Cu sulphides and also vein-reopening by later Cu-mineralization and new generation of disseminated or vein type mineralization. In addition, appearance of dark halo, as consuming intermediate chalcocite phase, around pyrite and chalcopyrite which gradually evolves as bornite, also extruding extra iron as fibrous hematite at the outer edge of bornite product replaced chalcopyrite, partially replacement of bornite and chalcopyrite to hypogene chalcocite and covellite-digenite in deep potassic are other HE evidences in the case study. Here, we draw on microscopic observations and SEM-BSE-EDS results, secondary hypogene genesis for some of bornite and chalcopyrite as a hypogene enrichment evidence. Observations from relogging show that potassic alteration has a relatively good preservation in the center of the deposit from depth to surface, but affected by intense overprinting of subsequent alterations towards margins. Evident function of ore-leaching at margins, also elevated copper grades in central parts of the deposit strongly suggest leaching-fixation mechanism. Where buffer potential of the rock is preserved copper fixation and where it totally eliminated almost complete leaching of copper happened. Consequently, we introduce leaching-fixation as index processes in hypogene enrichment at the case study. We suggest that identifying the nature of hypogene enrichment processes and its characterizations not only improve understanding about PCD's hydrothermal evolution, but also achieve exploration indicators, furthermore, industrial benefits in the production line. [ABSTRACT FROM AUTHOR]

Porphyry-type deposits are a vital source of green technology metals such as copper and molybdenum. They typically form in subduction-related settings from large, long-lived magmatic systems. The most widely accepted model for their formation requires that mantle-derived magmas undergo an increase in volatiles and ore-forming constituents in mid- to lower crustal reservoirs over millions of years, however, this is mostly based on observations from shallow, sporadically exposed parts of porphyry systems. To examine this paradigm, we have evaluated the timeframe and geochemical signatures of magmatism in a ~ 8 km palaeodepth cross-section through plutonic and volcanic rocks of the classic Yerington magmatic system, Nevada. We show that the magmas in the upper parts of the system (< 8 km) underwent a major and rapid change in chemistry over a period of < 200 kyrs that is coincident with the initiation of ore formation. We attribute this change to a shift from extraction of quartz monzodiorite and quartz monzonite magmas evolving in mid-crustal reservoirs, and that had relatively poor ore-forming potential, to extraction of volatile-rich granitic magmas from greater (~ 30 km) depths. As the granites crystallised, late stage melts were intruded through the carapace as aplite dykes which contain traceable expressions of the porphyry deposit-forming fluids. The rapid nature of the shift in ore-forming potential narrows the temporal-geochemical footprint of magmas associated with porphyry mineralisation and provides new constraints for exploration models. [ABSTRACT FROM AUTHOR]

A current mineral exploration focus is the development of tools to identify magmatic districts predisposed to host porphyry copper deposits. In this paper, we train and test four, common, supervised machine learning algorithms: logistic regression, support vector machines, artificial neural networks (ANN) and Random Forest to classify metallogenic 'fertility' in arc magmas based on whole-rock geochemistry. We outline pre-processing steps that can be used to mitigate against the undesirable characteristics of geochemical data (high multicollinearity, sparsity, missing values, class imbalance and compositional data effects) and therefore produce more meaningful results. We evaluate the classification accuracy of each supervised machine learning technique using a tenfold cross-validation technique and by testing the models on deposits unseen during the training process. This yields 81–83% accuracy for all classifiers, and receiver operating characteristic (ROC) curves have mean area under curve (AUC) scores of 87–89% indicating the probability of ranking a 'fertile' rock higher than an 'unfertile' rock. By contrast, bivariate classification schemes show much lower performance, demonstrating the value of classifying geochemical data in high dimension space. Principal component analysis suggests that porphyry-fertile magmas fractionate deep in the arc crust, and that calc-alkaline magmas associated with Cu-rich porphyries evolve deeper in the crust than more alkaline magmas linked with Au-rich porphyries. Feature analysis of the machine learning classifiers suggests that the most important parameters associated with fertile magmas are low Mn, high Al, high Sr, high K and listric REE patterns. These signatures further highlight the association of porphyry Cu deposits with hydrous arc magmas that undergo amphibole fractionation in the deep arc crust. [ABSTRACT FROM AUTHOR]

Porphyry indicator zircons (PIZ) are often used as an exploratory guide to distinguish fertile granitoid-hosted porphyry copper deposits (PCD). Alumina-saturated granitoids with higher zirconium (> 200 ppm) contents are often the hosts of PCD. REE profiling of zircon is used here to evaluate the chemistry of zircon from a blend of I- and A-type granitoids that hosts the ‘Kaziranga’ porphyry copper mineralization in the Karbi Hills of the Shillong Plateau. Zircon Hf(t) (1.69–9.88; av.4.65) and whole rock 87Sr/86Sr (0.703) of the Kaziranga granitoids suggest magma derivation in an intraplate or primitive island arc tectonic setting, in which the active mechanism of magma derivation was partial melting of a metasomatically enriched lithospheric mantle that was probably fertilized by an intraplate mantle plume. The fertility indicators with PIZ are grouped with respect to the distribution pattern of normalized REEs, as they exhibit low LREE and enriched HREE, large + Ce, and small -Eu anomalies. The hypogene alteration zones have developed on a regular basis, the potassic alteration zone being close to the central zone around Kuthori in the north Karbi Hills. Although the hosts demonstrate expansion and development of the hypogene alteration zones, the zircons from the mineralized granitoids of Kuthori central zone and granitoids of the nearby Panbari–Dallamara shear zone have similar REE pattern. The target zone’s zircon has higher values of ΣHREE, U, Th, Y, Nb, and Hf. The admissible range of fertile PCD is matched by the cross plots of critical element ratios, demonstrating high calculated Ti in zircon temperature (up to 828 °C).Graphical abstract: Porphyry indicator zircons (PIZ) are often used as an exploratory guide to distinguish fertile granitoid-hosted porphyry copper deposits (PCD). Alumina-saturated granitoids with higher zirconium (> 200 ppm) contents are often the hosts of PCD. REE profiling of zircon is used here to evaluate the chemistry of zircon from a blend of I- and A-type granitoids that hosts the ‘Kaziranga’ porphyry copper mineralization in the Karbi Hills of the Shillong Plateau. Zircon Hf(t) (1.69–9.88; av.4.65) and whole rock 87Sr/86Sr (0.703) of the Kaziranga granitoids suggest magma derivation in an intraplate or primitive island arc tectonic setting, in which the active mechanism of magma derivation was partial melting of a metasomatically enriched lithospheric mantle that was probably fertilized by an intraplate mantle plume. The fertility indicators with PIZ are grouped with respect to the distribution pattern of normalized REEs, as they exhibit low LREE and enriched HREE, large + Ce, and small -Eu anomalies. The hypogene alteration zones have developed on a regular basis, the potassic alteration zone being close to the central zone around Kuthori in the north Karbi Hills. Although the hosts demonstrate expansion and development of the hypogene alteration zones, the zircons from the mineralized granitoids of Kuthori central zone and granitoids of the nearby Panbari–Dallamara shear zone have similar REE pattern. The target zone’s zircon has higher values of ΣHREE, U, Th, Y, Nb, and Hf. The admissible range of fertile PCD is matched by the cross plots of critical element ratios, demonstrating high calculated Ti in zircon temperature (up to 828 °C). [ABSTRACT FROM AUTHOR]

The 18 × 4 km Davenda-Klyuchevskoe cluster in the Mogocha mineral district of the Siberian craton hosts gold, silver, molybdenum and copper in six types of mineralization. The general sulphide zoning at the Sergeevskoe and Klyuchevskoe deposits, the largest in the cluster, is similar to porphyry systems, but the orebodies form 4.5 × 1 km multiple linear sulphide-rich quartz-veinlet swarms, rather than a bulk mineralized envelope. Five types of mineralization formed at 162 − 150 Ma. They are clearly overprinted by northeast-striking epithermal Au-Ag carbonate-quartz veins. All mineralization is genetically linked to the Peak Klyuchi subvolcanic centre of Late Jurassic to Early Cretaceous age (159 − 132 Ma) which is part of the Amudzhikan intrusive complex, consisting of early complexly shaped ENE-striking granodiorite porphyry stock and dykes, intruded by magmatic to hydrothermal breccia and five generations of WNW-trending dykes of dioritic porphyry, hybrid porphyry, rhyolite, and ultimate lamprophyre. The dykes control or parallel five types of megastockwork orebodies within a dextral extensional strike-slip duplex. However, Au-Ag epithermal veins follow late-mineral northeast faults, dividing the megastockwork into several domains. The Davenda-Klyuchevskoe cluster is part of the Shilka Mo-(Au-Ag-Cu) metallogenic belt, striking within the Siberian craton just 25 km north in parallel to the Mongol-Okhotsk suture. Geochronological and petrological data suggest that the intrusive complex and its mineralization formed in relation to northward-dipping subduction prior to scissor-like suturing in this segment of the Mongol-Okhotsk Ocean in response to the northward push by the North China and Yangtze cratons towards Siberia. [ABSTRACT FROM AUTHOR]

Currently, 60% of the world’s copper production comes from porphyry copper deposits, often significantly enriched by surface weathering. This paper uses new global datasets and previous work to review the critical processes required for porphyry copper formation and supergene enrichment. Porphyry copper formation requires a subducting arc to create a source magma which traverses a thickened crust subject to high exhumation rates during formation, ranging from 100’s to 1,000’s m/m.y. High exhumation rates potentially trigger magma decompression, causing fluid release, opening fluid pathways along faults and lineaments and/or facilitating telescoping, whereby early porphyry-style mineralization is overprinted and enriched by high-sulfidation mineralization at shallower crustal levels. Later supergene enrichment of the deposit requires precipitation rates > 120 mm/yr and exhumation rates ranging from 10’s to 100’s m/m.y. This allows copper sulfide sources to be continually refreshed for weathering but restricts the amount of erosion. Using the Central Andes, one of the world’s most critical porphyry copper provinces, the understanding gained from analyzing these global databases can explain the temporal and spatial pattern of known deposits. These constraints were used to inform mappable target criteria and data required for mineral exploration at a range of different scales, from orogen (> 100,000 km2), to terrane (100,000–1,000 km2) to arc (1,000–100 km2). The results can be used to help illustrate and inform global exploration strategies for supergene-enriched porphyry copper deposits. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X24080014 [ABSTRACT FROM AUTHOR]

The Xiaoxi’nancha porphyry Au-Cu deposit is located in Yanbian, Jilin Province, NE China. Gold-Cu mineralization is mainly associated with chlorite-sericite alteration. The 40Ar/39Ar age of pre-mineralization hydrothermal biotite in potassic alteration defines a relatively well-defined cluster at ~ 111 Ma to 114 Ma with a total fusion age of 112.0 ± 0.3 Ma. In-situ secondary-ion mass spectrometry U-Pb dating of hydrothermal titanite occurring with chalcopyrite yielded an intercept age of 109.0 ± 2.4 Ma. The similarity between the biotite and titanite formation ages suggests a mineralization age of ~ 110 Ma. Chlorite, quartz and apatite coexist in equilibrium and are closely related to mineralization. The Al-in-chlorite geothermometer indicates a formation temperature of 236–351℃ (mean 309℃), and the quartz-apatite pair yielded an average formation temperature of 306℃. The in-situ δ34S compositions of sulfide have restricted and slightly positive values (pyrite 2.3 to 3.9‰, chalcopyrite 1.6 to 3.8‰ and molybdenite 2.3 to 3.7‰). The fluid δ18O values, calculated assuming quartz-fluid equilibrium, vary from 2.4 to 5.5‰ (average = 4.0‰). Therefore, the ore-forming hydrothermal fluids were of moderate-temperature with predominantly magmatic characteristics. Apatite exhibits distinct variations in structure and composition, and slight variations in oxygen isotopic composition. The areas in apatite with dark BSE textures are characterized by lower δ18O values, Cl contents and temperatures and higher F contents, consistent with the result of water–rock interaction rather than mixing with meteoric water. The water–rock interaction and its resulting cooling, can reduce the metal solubility, likely triggering mineralization at Xiaoxi’nancha. [ABSTRACT FROM AUTHOR]

The paper presents new data on the trace-element (REE, Y, and Sr) composition of calcite from stockwork Au–Cu porphyry ores and host rocks of the Kutuevsky occurrence, South Urals. Trace elements were analyzed by LA–ICP–MS in calcite and by ICP-MS in intrusive rocks and ophicalcite. We established that REE amounts and patterns of the calcite significantly varied and depend on the ore mineralization location in the metasomatic aureole. The ores in chlorite–sericite–quartz metasomatites in the central part of the gabbro-diorite and diorite intrusion are dominated by calcite, whose REE amounts and patterns are comparable to those of the intrusive rocks. We suggest that REE in the crystallized calcite were borrowed by fluid mainly from the intrusive rocks. Calcite in the ores hosted by biotite–epidote–chlorite–sericite–quartz metasomatites in the eastern inner-contact zone of the intrusive massif contains abnormally low REE amounts. The most likely REE source for this calcite is assumed to be the carbonate cement of the ophicalcites. REE fractionation was largely controlled by fluid temperature. When the calcite crystallized, the mineral-forming temperature exceeded 250°C, and therefore, Eu2+ dominated in the fluid, and the regime was reducing. [ABSTRACT FROM AUTHOR]