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Carlin-type gold deposits are among the most important gold-bearing hydrothermal ore systems and are mainly located in Nevada, USA, and southwestern China. However, the source and evolution of the ore-forming fluids for these deposits remain controversial, especially those found within China. In this study, lithium and oxygen isotopic analyses of quartz-hosted fluid inclusions are used to elucidate the source and evolution of the giant Shuiyindong Carlin-type gold deposit. Fluid inclusions trapped in quartz of three distinct genetic stages have low salinity (0.8–6.3wt% NaCl equiv.) and moderate temperature (154–343 °C), but display variable Li and O isotope signatures. The Li and O isotopes of stage I fluids (δ7Li values from + 5.1 to + 9.1‰; δ18O values from + 6.3 to + 10.0‰) indicate predominantly a magmatic source for the initial ore-forming fluids. The large variations of Li and O isotopes of stage II fluids (δ7Li values from + 9.3 to + 16.0‰; δ18O values from + 0.1 to + 7.7‰) suggest that the fluids are controlled by mixing of magmatic fluids and meteoric water, which in turn triggered the precipitation of gold-bearing sulfides. The isotopic compositions of stage III fluids (δ7Li values from + 15.5 to + 22.8‰; δ18O values from − 5.4 to − 2.8‰) confirm that the final fluids are dominated by meteoric water. Furthermore, this work demonstrates that the combined Li–O isotopic analysis of fluid inclusions is a powerful tracer to decode the source and evolution of ore-forming fluids in hydrothermal mineralizing systems. [ABSTRACT FROM AUTHOR]

The formation of Carlin-type gold deposits is poorly constrained, mainly due to the lack of accurate ages for gold mineralization. The Youjiang basin, SW China, represents the world's second-largest Carlin-type gold province after NV, USA. In this paper, we use hydrothermal apatite U–Th–Pb dating to systemically determine the mineralization ages of five Carlin-type gold deposits, namely, Shuiyindong, Jinfeng, Zimudang, Linwang, and Jinya, in the Youjiang basin. The hydrothermal apatite is characterized by intimate intergrowth with gold-bearing sulfides, presence of primary fluid inclusions, irregular morphology and cathodoluminescence zoning, and MREE-enriched composition patterns, indicating that it is clearly associated and coeval with gold mineralization. The concentrations of lattice-bound U and Th in the apatite are highly variable, making it suitable for in situ secondary ion mass spectrometry (SIMS) U–Th–Pb dating. The dating results of hydrothermal apatite from the five deposits show that they formed at ca. 150–140 Ma, contemporary with the widespread felsic magmatism and associated W–Sn mineralization to the east of the Youjiang basin, probably in response to slab breakup of the Paleo-Pacific oceanic plate beneath the South China continental plate. Our case story suggests that hydrothermal apatite could be a robust chronometer for age dating of sedimentary rock-hosted gold mineralization worldwide. [ABSTRACT FROM AUTHOR]

Gold in Carlin-type gold ores is commonly hosted in the arsenian pyrite rim, but the formation of arsenian pyrite and its contribution to Au adsorption are poorly understood. Based on our previous NanoSIMS Au mapping, we conducted SEM and HR-TEM analyses to examine the Au deportment and nanoscale texture of individual auriferous arsenian pyrite grains from the giant Carlin-type Lannigou gold deposit, SW China. The results indicate that the arsenian pyrite rim is composed of numerous nanoparticulate pyrite grains (rather than a single crystal), and gold nanoparticles (Au0) occur mainly in sub-rim with the highest Au content, which are porous and have lower degrees of order. We propose that nanoparticulate arsenian pyrite attachment and aggregation is the main mechanism for the arsenian pyrite rim growth, and such mechanism is crucial for the Au efficient enrichment for this giant gold deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple (Fe, Mn) or coupled (Cu, Ag coupled with In, Sb, Ga, Ge, Sn) substitution for Zn was observed in sphalerite. • The Zhaxikang is a magmatism-related medium to low-temperature hydrothermal vein deposit. • The sulfur in the Zhaxikang deposit is predominantly sourced from Jurassic marine sulfate or evaporite rocks. • The metals for the Zhaxikang deposit primarily originated from the basement metamorphic rocks (gneiss) of the Greater Himalayan Crystalline complex. The metallogenesis of collisional orogen has been a significant research topic for comprehending the linkage between magmatism, metamorphism, hydrothermalism and ore deposition. In Southern Tibet, the Zhaxikang deposit is a super-large Pb-Zn-Sb-Ag polymetallic deposit with metal reserves of 2.367 Mt Zn + Pb (average grade of 6.43 %), 0.2552 Mt Sb (average grade of 1.14 %), and 2960.6 t Ag (average grade of 101.64 g/t), constituting the largest deposit within North Himalayan Metallogenic Belt. However, the metal sources of the ore-forming material and mineralization process in this deposit remain a subject of controversy due to previous studies primarily relying on a bulk analysis of sulfides, which record the mixed results of multistage mineralization and intergrown minerals of different stages. The objective of this study is to constrain the sources and mineralization process of the Zhaxikang deposit through in-situ analyses of trace elements and sulfur isotopes in sphalerite. Based on ore textures and mineral paragenesis, four mineralization stages and three generations of sphalerite deposited respectively in stage 1 (Sp1), stage 2 (Sp2), and stage 4 (Sp3), were identified. The Pb and Zn mineralization mainly occurred in stage 2, while Sb and Ag were dominantly in stage 4. The trace elements characteristics (Cd, Fe, In, Ga, Ag, Cu, Co, and Mn) observed in sphalerite indicate that the Zhaxikang deposit could be a hydrothermal vein-type deposit associated with magmatism. The δ34S values of sulfides (7.7–18.4 ‰) in the deposit generally exhibit a slight elevation compared to those (4.1–12.9 ‰) of the Jurassic Ridang Formation slate, indicating that the sulfur of the deposit primarily originated from seawater sulfate in the slate through thermochemical sulfate reduction, although a small amount of contribution from mafic rocks also existed in stage 4. The Pb isotopes in stage 2 range from 19.662 to 19.705, 15.852 to 15.865, and 40.214 to 40.283 for the ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb, respectively, indicating that the metals primarily from the Greater Himalayan Crystalline complex (GHC) with a minor contribution from host rocks. While, the Pb isotopes in stage 4 range from 19.687 to 19.849 for 206Pb/204Pb, from 15.86022 to 15.885 for 207Pb/204Pb, and from 40.261 to 40.414 for 208Pb/204Pb, respectively, indicating that the metals originated from sulfides in the earlier stage as well as the more radiogenic GHC. [ABSTRACT FROM AUTHOR]

The reduced nature of the subducting slab has been used to explain the relatively poor endowment of economic porphyry copper deposits in Paleo-Tethyan arc systems. The presence of numerous porphyry Cu deposits in the southern Yidun terrane potentially challenges this model, because these deposits are thought to be the product of Paleo-Tethyan subduction. To investigate this, two representative deposits (i.e., Pulang and Songnuo porphyry Cu deposits) from the southern Yidun terrane have been studied. Zircon U-Pb ages of pre- and syn-mineral porphyries in Pulang are 221 ± 2 Ma (MSWD = 0.89) and 215 ± 2 Ma (MSWD = 1.50), respectively. Zircon and garnet U-Pb ages of the Songnuo syn-mineral porphyry are 217 ± 2 Ma (MSWD = 1.15) and 223 ± 5 Ma (MSWD = 0.97), respectively. The Pulang and Songnuo porphyries both have high whole-rock Sr/Y ratios with minor or no negative Eu anomalies, consistent with derivation from hydrous magmas that underwent minor early plagioclase crystallization but abundant amphibole fractionation. The two porphyry intrusions are characterized by high large-ion-lithophile elements (LILE: Th, U, Ba, Rb) abundances, and low concentrations of high-field-strength elements (HFSE: Nb, Ta, Ti, Zr, Hf). They have similar initial Sr isotope ratios from 0.7055 to 0.7073, ƐNd (t) values from − 4.3 to − 1.6 and zircon ƐHf (t) values of − 1.81 ± 1.34 (n = 47) that are distinct from published results for the Permian–Early Triassic Paleo-Tethyan arc granitoids in the Sanjiang region but similar to the Neoproterozoic arc intrusions in the nearby western Yangtze craton. The Pulang and Songnuo porphyries have relatively high zircon EuN/EuN* ratios (0.59 ± 0.04, n = 52) and calculated Δ log fO2 (FMQ) values (1.61 ± 0.23, n = 52), consistent with relatively oxidized magmas. This feature is similar to the published data for the Neoproterozoic arc intrusions (EuN/EuN* = 0.55 ± 0.08; Δ log fO2 (FMQ) = 2.14 ± 0.60), but distinct from the published data for the reduced normal Paleo-Tethyan arc magmas (EuN/EuN* = 0.29 ± 0.10; Δ log fO2 (FMQ) = − 0.68 ± 0.88). Given that the most recent tectonic reconstruction models suggest that the Paleo-Tethys Ocean closed before ~ 220 Ma, we propose that the Pulang and Songnuo porphyries Cu deposits were formed in a postsubduction setting from oxidized melts generated by reactivating the Neoproterozoic arc root, unrelated to Paleo-Tethyan subduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Jinding deposit contains high content of associated critical metal Cd, Tl, Ag. • The enrichment of Fe assists incorporation of components Ge + Mn + Pb + As + Tl. • The enrichment of Cd assists incorporation of components Cu + Ag + Sb. • Cd and Fe zonation at sphalerite indicate a potential exploration deposit. The Jinding deposit is well-known to contain high concentrations of metals Zn, Pb, Cd, Tl, Ag, etc. in the world. The associated critical metals and their substitution mechanisms were wildly concerned. This study investigated and compared sphalerites using a combination of textural, trace element, and sulfur isotopic analyses to give insights into element substitution mechanisms and possible sources of ore-forming fluids and to constrain processes involved in ore genesis of the world-class Jinding sediment-hosted Zn-Pb deposit. LA-ICP-MS analyses reveal chemical zoning in the sphalerites together with the coupling of two main groups of trace elements substitution mechanisms: one is Fe + Ge + Mn + Pb + As + Tl and vacancies to substitute Zn, and the other is Cd + Cu + Ag + Sb to substitute Zn. The incorporation of trace elements is facilitated by the replacement of Zn by Cd and Fe. These two group elements have distinct color oscillatory zonation and are intertwined in the trace element LA-ICP-MS element maps. The sulfur isotopic values show high isotope fractionation in the sphalerite from −28.4 to −0.5 ‰, suggesting a bacteriogenic sulfur origin at Jinding. Sphalerite sample has observed that sulfur isotope is correlated with Fe concentration and anti-correlated with Cd concentration. These variations in isotope fractionation and trace element disequilibrium partitioning were interpreted as the effects of temperature and pH with less influence from sulfur activity. These variability zones of sphalerite alternately enriched in Cd- and Fe-related elements suggested that ore fluids may flow from metal-fertile sedimentary/basement sequences during their ascent, and colloform sphalerite was likely formed by a high degree of supercooling, over-saturation, and rapid mixing between bacteriogenic sulfur and metal-rich in spaces of collapse dome. Based on our observations, we suggested that these variability zones of layered sphalerite alternately enriched in Cd and Fe would likely provide useful insight for a potential economic Zn-Pb and associated critical metals mineral exploration deposit. [ABSTRACT FROM AUTHOR]

The Paleo-Tethyan arc belt is host to a small number of porphyry Cu deposits the key controls on which remains poorly understood. It has been hypothesized that the Paleo-Tethyan arc magmas were reduced and therefore less fertile for porphyry Cu formation but few studies have been conducted to directly assess the magmatic oxygen fugacity. We investigate the magma fertility of eastern Paleo-Tethyan arc igneous rocks in the Sanjiang region, SW China, represented by the Maoding (268.3 ± 2.3 Ma), Suwalong (275.6 ± 1.4 Ma to 264.7 ± 1.4 Ma) and Baimaxueshan (255.7 ± 1.5 Ma to 249.3 ± 1.1 Ma) granitoids. They have geochemical features consistent with typical continental arc rocks, formed from partial melting of the mantle wedge, with increasing contamination of crust-derived melts over time. The presence of amphibole, high Sr/Y ratios (35 ± 20, n = 17), and lack of negative Eu anomalies (Eu N /Eu N ⁎ = 1.04 ± 0.3, n = 17) are consistent with derivation from hydrous magmas. Zircons from the intrusive rocks have relatively low Eu N /Eu N ⁎ (mostly <0.4) ratios and calculated ΔFMQ values (−2.1 ± 1.2, n = 86). Combined with apatite microphenocrysts with extremely low sulfur contents (< 0.12 wt% SO 3), it suggests that the intrusions originated from water-rich but reduced arc magmas, that were less fertile for porphyry Cu formation. Our study highlights that magmatic f O 2 is probably a critical control on the prospectivity of arc systems and confirms that zircon and apatite compositions can be used to evaluate porphyry Cu fertility. • The Paleo-Tethyan arc igneous rocks were dated from ~275 to 249 Ma. • They were derived from partial melting of mantle wedge during MASH processes. • These arc magmas were reduced and less fertile for porphyry Cu formation. • Zircon and apatite compositions can be used to evaluate porphyry Cu fertility. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrite of Carlin-type Au deposits in the Youjiang Basin were analyzed by Nano-SIMS. • The δ34S values Au-bearing pyrite of Linwang vary inversely with Au concentrations. • Initial auriferous fluids of Linwang were sourced from magmatic-hydrothermal systems. • Reduced sulfur in ore-forming fluids of Badu was dominated by sedimentary sulfur. • Sedimentary sulfur contamination result in variable δ34S values of Au-bearing pyrite. The Youjiang Basin in Southwest China is the world's second largest Carlin-type gold (Au)-producing region. However, the source of reduced sulfur that accounts for Au transport in ore-forming fluids remains controversial. Finely characterizing the sulfur isotopic compositions (δ34S values) in micron-scale zonation of Au-bearing pyrite is the key to clearly identify sulfur source. Here, we used high-resolution nanoscale secondary ion mass spectrometry (Nano-SIMS) to characterize the temporal variation in δ34S values and its relationship with metal contents across Au-bearing pyrite from the Linwang and Badu deposits in the Youjiang Basin, with the aim of monitoring the source and evolution of reduced sulfur in auriferous fluids. The Au-bearing pyrite rims in the Linwang deposit contain three growth stages that record episodic injections of Au- and As-rich fluids. Within these rims, the δ34S values vary inversely with Au concentrations. The inner rims with the high Au contents have δ34S values of −1.7‰ to +3.3‰ that are comparable to those of magmatic sulfur. The outer rims with decreasing Au contents have δ34S values of +1.3‰ to +15.7‰ that gradually approach those of pre-ore pyrite in the host rock. Such a variation indicates that the reduced sulfur in the initial Au-bearing ore-forming fluids was primarily originated from deep magmatic-hydrothermal systems while the host rock-derived 34S-enriched sulfur increasingly dominated through fluid-rock interactions during mineralization. In contrast, Au-bearing pyrite from the Badu deposit has positive δ34S values ranging from +9.0‰ to +25.8‰, which overlap those of diagenetic pyrite in the Devonian sedimentary rocks. Combining the intimate spatial association between Au mineralization and the Devonian strata, we propose that the initial ore-forming fluids have leached substantial sulfur from the Devonian strata. Significant contaminations of sedimentary sulfur erased the primary sulfur isotopic signals of the initial auriferous fluids. Our interpretations of these two deposits may also apply to other Carlin-type Au deposits in the Youjiang Basin, where δ34S values of Au-bearing pyrite show host rock-dependent variations. This study demonstrates that high-resolution Nano-SIMS sulfur isotope and elemental analysis of Au-bearing pyrite is a potent tool for tracing the source and evolution of reduced sulfur in ore-forming fluids for sedimentary-host Au deposits worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] • The differences in mineral composition were related to temperature, alteration and hydrothermal fluid. • Ag ranges n*103 ∼ n*104 ppm in galena, n*10 ~ n*103 ppm in sphalerite and pyrite. Sphalerite has higher Au and Ag. • Silver occurs as a solid solution in samples with massive textures and as micro-inclusions in alteration samples. • The minor and trace elements are typical characteristics of massive sulfide deposits in the LSKD. Sphalerite, pyrite and galena are common sulfide minerals in Zn–Pb–(Ag) deposits, containing minor and trace elements that can be used to constrain the ore-forming processes. The Lengshuikeng Ag–Pb–Zn deposit (LSKD) is one of the largest silver deposits in China. The mode of silver occurrence in sulfides remains unclear except for individual silver minerals. In this study, we analyzed the minor and trace element contents of sulfide minerals from massive, vein, and veinlet-disseminated ores by in-situ laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS). The elemental compositions of sulfide minerals are variable. Combining petrographic observations and previous studies, we suggest that the sulfide minerals from two types of mineralization (porphyry and strata-bound types) were formed in a same hydrothermal system, and their content of minor and trace elements mainly is influenced by temperature, alteration of wall rocks and composition change of hydrothermal fluid. The Ag content in galena ranges n*103 ∼ n*104 ppm, whereas that in both sphalerite and pyrite ranges from n*10 ∼ n*103 ppm. Except for galena, a higher content of gold (mean = 0.76 ppm) and silver (mean = 151 ppm) occurs in sphalerite compared with the content of gold (mean = 0.26 ppm) and silver (mean = 69.9 ppm) in pyrite. Generally, altered samples display higher Ag and Au contents in pyrite and sphalerite. Silver occurs in the form of a solid solution in sulfides from samples with massive textures, and as micro-inclusions in sulfides from altered samples. The contents of minor and trace elements (e.g. Cd and In) and their ratios (Ga/In, Zn/Cd and Cd/Fe) are not always sensitive to the temperature and processes of deposit formation. We suggest that sulfides from samples with massive texture and limited alteration are suitable for determining the genetic type of the deposit. Our results show that the hydrothermal fluid is a magmatic fluid related to porphyry granite in the LSKD. [ABSTRACT FROM AUTHOR]

[Display omitted] • The magmatic-hydrothermal system of Yangla skarn Cu deposit is relatively reduced. • The barren quartz porphyry was also originated from reduced magmas and thus less fertile for porphyry Cu formation. • Intense fluid-carbonate rocks interaction and fluid focusing could be the key to formation of the reduced Yangla Cu deposit. In the Paleo-Tethyan orogenic belt, reduced mineralization systems result in extensive saturation and segregation of magmatic sulfide phases, which in turn leads to the loss of chalcophile elements and hinders the precipitation of large amounts of copper. As a result, porphyry Cu deposits are rare within the belt. In this contribution, we investigate the composition of zircons from the granodiorite, fluid inclusions and hydrothermal scheelite from orebodies of the Yangla Skarn Cu deposit, and assess the magmatic-hydrothermal redox state of the system. The igneous zircons from ore-causative granodiorite have negative Eu anomalies (Eu N /Eu N * = 0.27 ± 0.03, n = 11) and the calculated ΔFMQ values are -0.23 ± 0.31 (n = 11). The ore-forming fluids in the pre-ore stage was rich in CH 4 , and precipitating hydrothermal scheelite in the syn -ore stage with low Mo contents (Mo = 17.4 to 149 ppm, mean 57.7 ppm) and positive Ce anomalies (Ce N /Ce N * = 1.14 ± 0.06, n = 29). The geochemistry suggests that the magmatic-hydrothermal system at Yangla is relatively reduced, consistent with the abundant development of pyrrhotite in the ore body. In addition, we have carried out zircon SIMS U-Pb dating and trace analysis of the barren quartz porphyry in the Yangla ore field, which gives an emplacement age of 227 Ma and is also derived from reduced magmas (ΔFMQ = -1.27 ± 0.55; Eu N /Eu N * = 0.32 ± 0.10, n = 7) that were less fertile for porphyry Cu formation. By comparing with the barren quartz porphyry, we suggest that the key control of the skarn ore body may have been that the low-permeability of carbonate units seal the mineralizing fluids, enhancing fluid-carbonate reactions and concentrating the sulfides in a relatively small area. Without these processes, it can only form barren porphyry system. We highlight that, unlike typical porphyry Cu deposits, intense fluid-carbonate rocks interaction and fluid focusing could result in skarn Cu formation, even though in relatively reduced magmatic-hydrothermal conditions. [ABSTRACT FROM AUTHOR]

The genesis of the giant Ag-Cu-Pb-Zn polymetallic mineralization in the northern Lanping basin, Southwest China, remains controversial. To address the sources of metals, a systematic study on Hg isotope compositions was conducted for the Cu-dominated deposit at Baiyangping and the Pb-Zn-dominated deposits at Fulongchang and Liziping. The Cu deposit shows positive Δ199Hg signatures (0.14 ± 0.13‰), in contrast to the Δ199Hg of the Pb-Zn deposits (− 0.09 ± 0.06‰). As positive Δ199Hg values are commonly observed in marine sediments and the Lanping Triassic marine sedimentary rocks show exclusively positive Δ199Hg signals (0.03 ± 0.07‰), the Hg in Cu ores was mainly sourced from the Triassic strata. The negative Δ199Hg signals observed in the Pb-Zn deposits, typical of terrestrial Hg, agree roughly with those of the Jurassic to Paleocene terrestrial sedimentary rocks (− 0.05 ± 0.08 ‰), indicating that the terrestrial strata provided the Hg in Pb-Zn ores. Compared to the source rocks, the Cu deposit shows isotopically lighter Hg enrichments (δ202Hg = − 2.30 ± 0.35‰), possibly resulting from fractionations induced by Hg2+ sorption, organic complexation, and precipitation of Hg-bearing sulfides. The Pb-Zn deposits show comparable or slightly heavier δ202Hg (− 0.56 ± 0.48‰); moreover, δ202Hg values of late-stage sulfides are higher than early-stage δ202Hg values, suggesting that the δ202Hg variation was primarily caused by sulfide precipitation. Thus, Hg isotope data indicate that separate hydrothermal events resulted in Cu and Pb-Zn mineralization. More importantly, this study reveals the great potential of Hg isotopes to discriminate sedimentary sources of metals for low-temperature hydrothermal deposits. [ABSTRACT FROM AUTHOR]

The late Mesozoic antimony (Sb) mineralization belt in South China hosts a large portion of the world's Sb reserves. However, the source and mineralization processes of these Sb deposits remain controversial. Here, we measured mercury (Hg) concentrations and isotopic compositions of stibnite in the Banpo Sb-only and Woxi Sb-polymetallic ore deposits, as well as associated rocks in the Yangtze Block in order to constrain the metal sources and ore formation processes in the South China Sb mineralization belt. Stibnite samples from both deposits exhibit significant enrichment in Hg (4.23–50.6 ppm) and have higher δ202Hg values (−0.47‰ to 2.03‰) than the studied Precambrian basement rocks (−1.42‰ to 0.59‰), Paleozoic sedimentary rocks (−2.40‰ to −0.32‰), and other natural Hg reserves (e.g., marine and continental systems). This indicates that significant mass-dependent fractionation of Hg isotopes occurred during hydrothermal processes. Negative to slightly positive Δ199Hg values of −0.17‰ to 0.02‰ were obtained for stibnite from the studied deposits, similar to values for the Precambrian basement rocks, but different from those of the Paleozoic sedimentary rocks and data previously reported for mantle materials. This suggests that Precambrian basement rocks were the source of Hg and associated metals. Our data and the tectonic evolution of South China indicate that late Mesozoic asthenospheric upwelling, in response to the Paleo-Pacific oceanic slab foundering, generated heat that drove the circulation of fluids in the basement and crustal basinal rocks. These fluids leached Sb, Hg, and other metals from the Precambrian basement rocks and formed the world-class Sb mineralization belt in South China. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sphalerite chemistry combined with ML methods were used to classify deposit types. • KNN, NN, and RF algorithms are more efficient than other ML methods in the classification tasks. • Ge, Sn, Co, Mn, Ga, and In in sphalerite are the most important discriminant elements. • Binary discrimination diagrams based on PCA and PLS-DA are provided. Sphalerite can form in different geological environments and is the main ore mineral of most Pb-Zn deposits. Trace elements in sphalerite combined with machine learning (ML) methods have been used for deposit type discrimination. However, the performance of different multivariate and ML methods is not systematically compared. Here more than four thousand laser ablation inductively coupled plasma mass spectrometry data from more than one hundred deposits were compiled and investigated by different multivariate and ML methods. Unsupervised multivariate and ML methods including principal component analysis (PCA) and t -distributed stochastic neighbor embedding (t -SNE), and supervised multivariate and ML methods including partial least squares-discriminant analysis (PLS-DA), logistic regression (LR), support vector machine (SVM), K-nearest neighbors (KNN), random forest (RF), naïve Bayes (NB), and neural network (NN) are used to classify deposit types. The models are constructed for five deposit types, Mississippi Valley-type (MVT), Volcanogenic Massive Sulfide (VMS), sedimentary exhalative (SEDEX), Epithermal, and Skarn deposits, based on twelve elements in sphalerite, Fe, Pb, Mn, Co, Cu, Ga, Ge, Ag, Cd, In, Sn, and Sb. The PCA and PLS-DA methods show similar clustering results, where Epithermal, MVT, SEDEX, and Skarn deposits can be separated from other deposit types. The t -SNE method is only efficient in discriminating MVT, SEDEX, and Epithermal deposits. The KNN, RF, and NN methods show better performance than LR, SVM, and NB in terms of average accuracy and precision. The PCA, t -SNE, and PLS-DA methods have advantages in data visualization, whereas KNN, NN, and RF methods are more suitable for classification tasks. Feature importance analyses of the PLS-DA and RF methods show that the most important discriminant elements in the classification are Ge, Mn, In, Sn, Ga, and Sb. The models based on PCA, PLS-DA, KNN, NN, and RF are used to predict sphalerite samples with uncertain origins. All the models give similar classification results for deposit types, which are consistent with the ore-forming geological setting. The multivariate and ML models, including discrimination diagrams of PCA and PLS-DA, can be used as the first screening for the type of Pb-Zn mineralization in mineral exploration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal zircons intergrown with gold-related minerals and containing primary fluids inclusions were identified from the Badu gold deposit in the Youjiang basin, SW China. • The hydrothermal zircons display high LREE contents and relatively flat light rare-earth element patterns, consistent with hydrothermal zircon reported worldwide. • In-situ SIMS and LA-ICP-MS U-Pb datings on the hydrothermal zircons reveal that the Badu deposit formed at ca. 140 Ma, probably in response to the Early Cretaceous large-scale lithospheric extension of South China. Selecting a robust chronometer is crucial to determine the primary mineralization age of the deposits that have witnessed multiple hydrothermal events. The Youjiang basin of South China hosts the world's second-largest Carlin-type gold province. However, the age of the Carlin-type gold mineralization remains highly debated, partly due to the presence of multiple hydrothermal events that may have disturbed the primary isotopic system with low durability. Hydrothermal zircon is a robust chronometer that can survive multiple hydrothermal events. To this end, in this study, we report in-situ secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb dating results of hydrothermal zircon identified in carbonate–sericite–sulfide–altered dolerite from the Badu Carlin-type gold deposit to constrain the timing of gold mineralization. The hydrothermal zircons exhibit subhedral to anhedral morphologies, sector cathodoluminescence zonings, and contain gold-related mineral assemblages of arsenian pyrite, quartz, sericite, and carbonate. Primary two-phase fluid inclusions also commonly occur in the hydrothermal zircons. Compositionally, these zircons feature relatively flat light rare-earth element (REE) patterns, high La contents, low (Sm/La) N values, and small Eu and Ce anomalies, which are different from the magmatic counterparts of the Badu pluton but consistent with those of hydrothermal zircons reported worldwide. These features indicate that the hydrothermal zircons are probably paragenetically associated with the gold mineralization. Consequently, the U–Pb ages of ca. 140 Ma of these zircons, which are much younger than those of the magmatic zircon in the fresh dolerite, can represent the timing of primary gold mineralization of Badu. Our new data suggests that there truly was an episode of gold mineralization during the Early Cretaceous in the Youjiang basin, which may have been driven by large-scale lithospheric extension in the interior of South China. This study demonstrates that hydrothermal zircon could be a robust clock for investigating the timing of magmatic rock-hosted Carlin-type gold deposits. [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]

B Retraction Note to b : B Mineralium Deposita (2022) 57:399-415 b https://doi.org/10.1007/s00126-021-01070-3 The Editors-in-Chief have retracted this article because Table 2 contains data used in a previously published article (Liu et al. [1]). All authors agree to this retraction and to the wording of this retraction notice. [Extracted from the article]

Porphyry Mo deposits have traditionally been classified into two major classes, arc-related and Climax-type, based on the tectonic setting and chemistry of associated intrusions. Although there is a consensus that porphyry Mo systems were formed by the optimal coincidence of geological processes operating at different scales, it is unclear what key parameter(s) render systems productive and whether the two classes of porphyry Mo deposits are unique in their mode of formation, or if they share fundamentally similar geological processes. These questions are important as a clearer understanding of the optimum conditions for the formation of porphyry Mo deposits is a prerequisite for more efficient exploration. This contribution presents a detailed assessment of the factors affecting the formation of porphyry Mo deposits through the investigation of barren and mineralized intrusions from the arc-related Songbei-Yangjiazhangzi-Lanjiagou (SYL) ore zone and the Climax-type Hashitu deposit of northeastern China. Our results show that the syn-mineralization intrusions from the SYL ore zone are quite evolved (SiO2 ~ 75 wt%; Na2O+K2O ~ 8.7 wt%) and are characterized by apparent light rare earth element (LREE) enrichments (LaN/YbN = 2.7–33.1) and moderate negative Eu anomalies (Eu/Eu* = 0.4–0.7). They show enriched zircon Hf isotopic compositions [εHf(t) = –11.9 to –4.8], indicating their parental magmas were likely derived from an ancient crustal source. Melt inclusions from the SYL syn-mineralization intrusions contain negligible F and Cl. In contrast, Hashitu syn-mineralization intrusions are characterized by weak LREE enrichments (LaN/YbN = 2.2–6.9) and strong negative Eu anomalies (Eu/Eu* = 0.02–0.10), with SiO2 and Na2O+K2O contents similar to the SYL syn-mineralization intrusions. They show depleted zircon Hf isotopic compositions [εHf(t) = 3.1–5.0], indicating their parental magmas were likely derived from a juvenile crustal source. Melt inclusions from the Hashitu syn-mineralization intrusions contain up to 0.4 wt% F and 0.03 to 0.09 wt% Cl. However, in both cases, the syn-mineralization intrusions are Mo-poor (1–7 ppm Mo), oxidized (above the quartz-fayalite-magnetite buffer), water-saturated (4.4–7.8 wt% H2O), and were emplaced at palaeodepths of 3.3 to 8.3 km. These data imply that magma source composition is not a key factor in the formation of porphyry Mo deposits. In contrast, magma oxygen fugacity, water content, and emplacement depth appear to play fundamental roles in the formation of porphyry Mo deposits of both arc-related and Climax-type. Within individual deposits, no systematic differences between pre- and syn-mineralization intrusions are observed in terms of magma source, fractionation degree, oxygen fugacity, emplacement depth, and volatile and Mo contents. Instead, a crucial apparent difference lies in the geometry of the intrusions, i.e., pre-mineralization intrusions generally occur as flat, ponded bodies, whereas syn-mineralization intrusions commonly develop as small stocks or dikes. Our results, in combination with an examination of other porphyry Mo systems, suggest that the sudden depressurization of magma chambers and subsequent venting of voluminous fluids along focusing structures (such as small stocks or dikes) most likely plays a critical role in the formation of porphyry Mo deposits of both arc-related and Climax-type. The findings of this study indicate that fluid processes in the shallow crust are pivotal for the formation of porphyry Mo deposits and that settings with ideal magmatic-hydrothermal architectures are most likely to develop into productive porphyry Mo systems. [ABSTRACT FROM AUTHOR]

The Baiyangping Cu–Ag polymetallic ore district is located in the northern part of the Lanping-Simao foreland fold belt, between the Jinshajiang-Ailaoshan and Lancangjiang faults, and the deposit can be divided into eastern and western ore zones. Based upon microscope observation of ore minerals and analysis of zinc, copper, and strontium isotope composition, we conclude that: (1) the zinc isotopic compositions of sphalerite from the eastern and western ore belt of the Baiyangping polymetallic ore deposits are enriched in both the heavy (− 0.09‰ to + 0.15‰) and light (− 0.19‰ to − 0.01‰) zinc isotopes. Rayleigh fractionation is likely the additional factor controlling the observed temporal and spatial variations in zinc isotopes in the two studied ore zones. The zinc isotopic composition in the Baiyangping polymetallic Pb–Zn deposits may have the same fractionation as that of magmatic-hydrothermal, VHMS, SEDEX, and MVT deposits, as demonstrated by geological and other geochemical evidence; (2) the range of δ65Cu in massive tetrahedrite is from − 0.06‰ to + 0.12 ‰ that relates to the early stages of ore-formation, which are higher than that of venial chalcopyrite (from − 0.72‰ to − 0.07‰) formed at a late ore-forming stage in the western ore belt. Different ore-forming stages and alteration or leaching processes are likely the main factors controlling the observed variations in copper isotopes in the western ore zone; (3) the 87Sr/86Sr value of hydrothermal calcite in eastern (0.7080–0.7093) and western (0.7085–0.7113) ore belt suggested that mineralization of early calcite, with 87Sr/86Sr values much higher than in ancient Late Triassic seawater, may be related to recrystallization from a radiogenic Sr-rich or silicifying fluid, either from the strata that the ore-forming fluid flows through or from other fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ge is mainly coupled with Cu in sphalerite, locally associated with Pb, Ag, and Mn. • The substitution mechanism of Ge will vary with textures and color of sphalerite. • Crystal structure or planes, texture, and temperature affect Ge, Ga, In contents. • Ge, Ga, and In behave differently during sphalerite precipitation. The low-medium temperature Zn-Pb deposits in the Sichuan-Yunnan-Guizhou (SYG) metallogenic region contain not only Pb and Zn but also abundant critical metals such as Ge, Ga, and In. The majority of previous studies focus on the genesis of Pb and Zn metals, and the research on Ge, Ga and In in the SYG region has become a topic in recent years due to economic importance of these metals. In this review, the distribution, occurrence, and enrichment mechanism of Ge, Ga, and In in Zn-Pb deposits in the SYG region is summarized. Sphalerite is the main host mineral of Ge, Ga, and In, with contents of up to ∼1300 ppm, ∼600 ppm, and ∼1191 ppm, respectively. Pyrite from the Fule Zn-Pb deposit is also rich in Ge (up to 340 ppm), which may be due to involvement of magmatic components in the ore-forming fluids. Germanium, Ga, and In mainly appear in the form of isomorphism in sphalerite. Independent minerals of Ge such as ruizhongite (Ag 2 □)Pb 3 Ge 2 S 8), are only found in the Wusihe Zn-Pb deposit. Copper is the main coupling ions for substitution of Ge, Ga, and In in sphalerite. However, the positive correlation of Ge with Pb, Mn and Ag in the sphalerite of Huodehong, Shaojiwan, Shanshulin, and Qingshan Zn-Pb deposits may indicate other means of substitution or existence of nanometer Ge minerals with similar composition to the ruizhongite. The substitution mechanisms of Ge and Ga vary with layers in the zoned sphalerite from the Nayongzhi Zn-Pb deposit, possibly indicating that physical or chemical variations in fluids will affect the substitution ways of Ge and Ga in sphalerite. The growth direction and crystal structure of ZnS also exert control over the contents of Ge, Ga, and In. The enrichment degree of Ge, Ga, and In changes between (1 1 0) and (1 1 1) crystal planes, and the wurtzite structure is beneficial to the infiltration of large ions (Ge, Ga, and In). Compared to sphalerite with euhedral texture, colloform sphalerite is conducive to the enrichment of Ge. For zoned sphalerite such as the rhythmic banding and the conventional zone, the former lacks zoning of Ge, Ga and In but the latter shows elemental zonation and Ge is enriched in the black domains. The correlation between the contents of Ge, Ga, and possible In in sphalerite and Pb or Zn isotopes of sulfides indicates the significant contribution of basement rocks for the enrichment of these metals. During the mineralization process, Ge tends to be enriched in dark or early sphalerite, including the Daliangzi, Tianbaoshan, Huize, Nayongzhi, Fule, Fuli, Wusihe, and Maoping deposits, which may be due to the variations in temperature or fluid evolution. The opposite variation trend of Ge and Ga with sphalerite color or stage in the Daliangzi, Nayongzhi, Maoping, Shaojiwan, and Wusihe Zn-Pb deposits indicates that Ge and Ga may behave differently during precipitation of sphalerite. [ABSTRACT FROM AUTHOR]

The Sanjiang base metal metallogenic belt (SMB) in southwestern China is characteristic of composite mineralization during the India-Asia continental collision. However, the geodynamic settings of the composite processes of this belt are poorly understood. The Lanuoma deposit, located in the Changdu Basin in the central segment of the SMB, is a Zn-Pb-Sb polymetallic deposit. The cross-cutting relationships and paragenetic mineral associations suggest the superimposition of a late Sb-Pb mineralization event over an early Zn-dominant mineralization event. Calcite is the main gangue mineral, intergrown with late Sb-Pb minerals (e.g., boulangerite, zinkenite, sorbyite and plagionite). In situ U-Pb dating by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) was successfully carried out on calcite from this deposit, and restricts the Sb-Pb mineralization to 19.7 ± 1.6 Ma, with a mean square weighted deviation (MSWD) of 1.2. This age is approximately synchronous with that of strike-slip shearing-related leucogranites in the marginal orogens; together with previous data, this result suggests that the contemporaneous magmatism significantly contributed to the ore-forming fluids associated with the Sb-Pb mineralization. Overprinting of the Miocene Sb-Pb event in a transtensional regime on the Oligocene transpression-driven Zn mineralization resulted in the characteristic Zn-Pb-Sb assemblage at Lanuoma. Moreover, this study indicates that the SMB holds great exploration potential for Sb(-Pb) resources. [Display omitted] • In situ U-Pb dating of calcite suggests an ~20 Ma Sb-Pb mineralization at Lanuoma. • The Sb-Pb mineralization was related to the contemporary magmatism induced by shearing. • Great exploration potential for Sb-Pb resources is suggested in Sanjiang region. [ABSTRACT FROM AUTHOR]

Magmatic rocks from intra-oceanic arcs are critical for understanding the formation of continental crust and tectonic evolution. The early tectonic evolution of the Neo-Tethyan Ocean before the final Indo-Asia collision remains mysterious, and the geodynamic processes that triggered the Cretaceous magmatism in central Myanmar is still debated. The Cretaceous magmatic complex in the Banmauk-Kawlin area (BKC), west Myanmar terrane (WMT) is composed of the Kanza Chaung granitoid batholith, the Mawgyi Volcanic rocks, and the Pinhinga plutonic complex. Zircon U-Pb dating results of various rocks from the Kanza Chaung batholith suggest magmatism lasted from ca. 110 to ca. 94 Ma, roughly overlapping with new geochronological data for the Mawgyi Volcanics. Mafic rocks, including basalts from the Mawgyi Volcanics and gabbros from the Kanza Chaung Batholith, have geochemical features resembling intra-oceanic arc magmas, characterized by high large-ion-lithophile elements (LILEs) and low high-field-strength elements (HFSEs) and flat trace element patterns. They have depleted Sr (initial 87Sr/86Sr = 0.7035–0.7054) and Nd (εNd(t) = 0.39–6.71) isotopic compositions, with zircon εHf(t) values ranging from +5.8 to +16.1, probably derived from partial melting of the mantle wedge. Diorites formed by differentiation of basaltic magma have similar trace element patterns and Sr-Nd isotopes. The granitic rocks were likely originated from partial melting of juvenile arc lower-crust, indicated by their high SiO 2 (>65.0 wt%), low MgO (<2.50 wt%) and depleted Nd and zircon Hf isotopes. The εNd(t) values of the BKC shift markedly (from ~ + 7 to 0) from 105 to 94 Ma, which correlates with a temporal increase of Th/Nb, La/Ta, and La/Sm. Given the juvenile characteristics of the WMT crust, this can be explained by exotic isotopically enriched crustal components subducted into the mantle source, rather than steady-state sediment subduction and crustal contamination. Given the Albian unconformity in the WMT and recent paleomagnetic data, such continent crustal components were likely introduced by collision followed by subduction of Greater India-derived continental sliver beneath the WMT. Thus crust with an Indian continent affinity was possibly accreted to an intra-oceanic arc (WMT) during the mid-Cretaceous. • The Cretaceous Banmauk-Kawlin igneous complex (BKC) was in an intra-oceanic arc setting. • Lowering of the BKC εNd(t) values could result from exotic crustal component. • Continental ribbon collided with an intra-oceanic arc occurs at ca. 105 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pulang composite intrusion defined a magmatic duration of 10 m.y. from ∼226 Ma to ∼216 Ma. • Six porphyry phases (i.e., premineralized and synmineralized porphyries) at Pulang were all derived from relatively oxidized and hydrous magmas. • The synmineralized porphyries showed higher magmatic sulfur and chlorine contents than those for the premineralized porphyry phases. • Magmatic sulfur and chlorine contents might be important for Pulang porphyry Cu-Au formation. The giant Pulang porphyry Cu-Au district (446.8 million tonnes at 0.52% Cu and 0.18 g/t Au) is located in the southern Yidun terrane of the Sanjiang (Three-river) region, southwest China. It has six phases of porphyry intrusions: premineralized fine-grained quartz diorite (FQD) and coarse-grained quartz diorite porphyry (CQD), the main synmineralized quartz monzonite porphyry (QMP), and late synmineralized granodiorite porphyry (GP), diorite porphyry (DP), and aplite. New zircon U-Pb ages for the premineralized FQD and late synmineralized GP, DP, and aplite are 226.3 ± 2.6 Ma (MSWD = 1.9), 216.4 ± 1.0 Ma (MSWD = 2.0), 216.0 ± 1.1 Ma (MSWD = 1.7), and 216.0 ± 1.5 Ma (MSWD = 1.7), respectively. All Pulang porphyry rocks have high whole-rock Sr/Y ratios (37.8–184) with minor or no negative Eu anomalies (0.73–1.04), and are characterized by high large-ion-lithophile-element (LILE: Th, U, Ba, Rb) abundances and low high-field-strength-element (HFSE: Nb, Ta, Ti, Zr, Hf). Zircons from premineralized FQD and synmineralized GP, DP, and aplite rocks have consistently high Eu N /Eu N * ratios (mostly > 0.4). The magmatic oxygen fugacity calculated from zircon compositions, show that the FQD (ΔFMQ = 1.59 ± 0.43), GP (ΔFMQ = 1.52 ± 0.18), DP (ΔFMQ = 1.52 ± 0.30), and aplite (ΔFMQ = 1.75 ± 0.60) were all derived from moderately oxidized magmas. Magmatic water contents estimated from amphibole compositions and the extensive presence of amphibole phenocrysts suggest that H 2 O contents are >4 wt%. Together with the published results for premineralized CQD and main synmineralized QMP, it is concluded the causative magmas for the six porphyry phases at Pulang were all relatively oxidized and hydrous. The difference between premineralized FQD and CQD and synmineralized QMP, GP, and DP are reflected in magmatic chlorine and sulfur contents. To minimize the effect of hydrothermal alteration, the apatite microphenocrysts enclosed by least altered phenocrysts were selected for analyses. The Cl contents of magmatic apatite microphenocrysts from the synmineralized QMP (avg = 0.340 ± 0.192, n = 26), GP (avg = 0.317 ± 0.151, n = 21), and DP (avg = 0.179 ± 0.112, n = 18) are significantly higher than those from the premineralized FQD (avg = 0.046 ± 0.032, n = 9) and CQD (avg = 0.043 ± 0.034, n = 13). Similarly, the SO 3 contents of igneous apatite microphenocrysts from the synmineralized QMP (avg = 0.259 ± 0.156, n = 25), GP (avg = 0.203 ± 0.163, n = 20), and DP (avg = 0.306 ± 0.173, n = 18) are higher than those from the premineralized FQD (avg = 0.181 ± 0.136, n = 10) and CQD (avg = 0.085 ± 0.068, n = 6). The S-Cl contents of synmineralized melts estimated from apatite S-Cl compositions are higher than those of premineralized magmas, suggesting that the elevated magmatic S-Cl contents in the synmineralized porphyries might have been important for Cu-Au mineralization. This was likely due to S-Cl rich mafic magma recharge, supported by the presence of abundant mafic magmatic enclaves in the synmineralized QMP. [ABSTRACT FROM AUTHOR]