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Here we present our workflow, numerical models and results of the spatial distribution of chalcopyrite mineralization under the different porosity and permeability conditions of the host rocks of the Shaxi deposit. During the numerical modeling research, we tried to coupling heat transfer, fluid flow, material migration, mineralization reaction, and their coupling with porosity and permeability of rock. The results show that the porosity and permeability of the host rocks play a significant role in the mineralization of porphyry-type systems. The chemical properties of the strata restrict significantly on mineralization intensity and spatial extent rather than affecting the depth of mineralization. This paper also indicates that the numerical modeling method employed in this study can be used to predict the mineralization depth and spatial location of deep concealed porphyry-type deposits, aiding research in deep-seated mineral exploration. [Display omitted] • The porosity and permeability of the host rocks play a significant role in the mineralization of Shaxi porphyry-type deposit. • The chemical properties of the strata restrict significantly on mineralization intensity and spatial extent rather than affecting the depth of mineralization. • The numerical modeling may be used to predict the mineralization depth and spatial location of deep concealed porphyry-type deposits. The Shaxi porphyry-type Cu-Au deposit is located in the northwestern outer margin of the Luzong volcanic basin, which is situated in the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB), Eastern China. It is a large porphyry-type Cu-Au deposit with confirmed copper resources exceeding 1 Mt and gold resources exceeding 40 tons. Previous studies have extensively investigated the genesis, controlling structures, geochemical characteristics, fluid evolution, alteration zone, and ages of mineralization and host rocks in this deposit. However, research on the influence of the physical and chemical properties of the host rocks on the mineralizing processes has not been explored in detail. This study employs the finite element method to apply numerical modeling of multiple physical and chemical fields, interlinking heat transfer, fluid flow, material migration, mineralization reaction, and their coupling with porosity and permeability of rock, to investigation of the influence of different porosities, permeabilities, and chemical properties of the host rocks on the mineralizing processes in the Shaxi deposit. The results show that the porosity and permeability of the host rocks play a significant role in the mineralization of porphyry-type systems. The different porosity and permeability of the intrusions and strata control the depth, the mineralization intensity, the morphology of the ore bodies, and the spatial location of the mineralization center. The chemical properties of the strata significantly restrict the mineralization intensity and horizontal spatial rather than affecting the depth of mineralization. Furthermore, the formation of skarn-type deposits may require a longer period of time than that of porphyry-type deposits under the same mineralization conditions and ore grade. This paper also indicates that the numerical modeling method employed in this study can be used to predict the mineralization depth and spatial location of deep concealed porphyry-type deposits, aiding research in deep-seated mineral exploration. [ABSTRACT FROM AUTHOR]

Based on the study of typical sandstone-type uranium deposits in China, the paper summarizes the characteristics of sandstone-type uranium deposits. The metallogenic elements of sandstone-type uranium deposit can be summarized into 5 aspects, which are "Source", "Reservoir", "Barrier", "Migration" and "Accumulation". Based on the research of metallogenic elements, three types of sandstone uranium metallogenic models are established in this paper, including the surficial infiltration fluid metallogenic model (Fig. 1), deep hydrothermal metallogenic model (Fig. 2) and superimposed metallogenic model (Fig. 3). This paper provide a better under-standing of the sandstone-type uranium. Once applied to underground examples, these models may allow the prediction of uranium ore body distribution. [Display omitted] • Distribution of sandstone-type uranium deposits in the world and China. • The elements of sandstone-type uranium metallogenesis are recognized as: source, reservoir, barrier, migration, and accumulation. • The sandstone-type uranium deposits are categorized into three metallogenic models: surficial infiltration fluid metallogenic model, deep hydrothermal metallogenic model, and superimposed metallogenic model. With the rapid development of nuclear power, the world demand for uranium is increasing year by year. Sandstone-type uranium deposits, as the primary target for uranium exploration and mining, have attracted more and more experts and scholars to conduct in-depth research with respect to ore morphology, metallogenic mechanism, metallogenic characteristics, and metallogenic models. In China, a lot of large and ultra-large sandstone-type uranium deposits were initially discovered by learning from international researches. However, these researches could not support operations on the sandstone-type uranium deposits with complex metallogenesis, resulting in no significant uranium breakthroughs in China over the past ten years. It is urgent to understand the metallogenic characteristics and models of sandstone-type uranium deposits. As the most popular deposits in China, sandstone-type uranium deposits are poor in southern China and rich in northern China − 88 % of sandstone-type uranium resources are found in sedimentary basins in northern China, mainly in Jurassic and Cretaceous strata. Five elements of sandstone-type uranium metallogenesis are recognized, i.e., source, reservoir, barrier, migration, and accumulation. Analysis results show that the sandstone-type uranium deposits discovered in China are obviously source-controlled, and mostly distributed 50 km away from their sources. Uranium reservoirs are generally large braided river or large braided river delta deposits, and locally large meandering river and fan delta deposits. They appear evidently in zones, an oxidation zone, a transition zone, and a reduction zone, which are different in color, mineral composition, and element content. Usually, stable barriers are developed at the roofs and floors of uranium reservoirs, and they provide strong supports for the sustainable and steady progress of uranium metallogenesis. Fluids as the carrier for uranium migration can be divided into two types: surficial infiltration fluid and deep upwelling fluid. Uranium metallogenesis is mainly controlled by reductants and adsorbents. Moreover, changes in fluid pH and temperature can lead to changes in uranium solubility in the fluid, allowing uranium to precipitate and accumulate into ore. Uranium generally occurs in three states: uranium mineral, adsorbed uranium, and uraniferous mineral. Based on the style of fluid migration, the metallogenic models of uranium deposits are divided into three types: surficial infiltration fluid, deep hydrothermal metallogenic fluid, and superimposed metallogenic models. The surficial infiltration fluid metallogenic model have two types: phreatic infiltration-type and interlayer oxidation-type. [ABSTRACT FROM AUTHOR]

This paper studies the mineralization process and the ore-forming setting of the Kantian fluorite deposit in South China through the zircon U-Pb chronology, quartz Rb-Sr dating, whole rock geochemistry, H-O isotope and fluid inclusions. A mineralization model for the Kantian fluorite deposit is proposed as follows: The subduction of the Pacific plate during the late mid-Jurassic and late Jurassic led to the formation of several fault zones. As the subduction gradually decelerated and eventually ceased, continental extension and lithosphere thinning occurred, accompanied by upwelling of the asthenosphere. This asthenosphere upwelling facilitated melting of the lithospheric mantle, resulting in the ascent of magma into the lower crust. Consequently, the intrusion of magma into the lower crust caused substantial heat, triggering partial melting of the lower crust. The molten material then ascended along faults, generating a significant quantity of granites. During the Early Cretaceous period, the Yanshan cycle witnessed another notable phase of magmatic activity. The residual magmatic hydrothermal fluid from this period served as a source of heating, while the pre-existing fault structures provided favorable pathways and storage space. Atmospheric precipitation infiltrated into the depth along these faults, and the deep-seated residual magmatic hydrothermal fluid heated the infiltrated atmospheric water, inducing cyclic upwelling. The upward migration of hydrothermal fluid continuously extracted Ca and F elements from the granites. Ongoing interaction between the fluid and the surrounding rocks led to changes in pH, coupled with alterations in temperature and pressure, ultimately resulting in the precipitation of fluorite with associated alteration zones in the surrounding rocks. [Display omitted] • Ca and F element in the fluorite were derived through the surrounding rocks. • The ore-forming fluids belong to the NaCl-H 2 O system and exhibit characteristics of medium–low temperature, low salinity, and low density, and were derived from meteoric water. • The intrusion age of surrounding rock in Kantian fluorite deposit was 159.4 ± 2.2 Ma, and the ore-forming of fluorite was 135.6 ± 0.7 Ma. • The tectonic setting responsible for the diagenesis and mineralization processes is believed to be an intracontinental stretching environment associated with the subduction of the Pacific plate. The Yanshanian events have led to the development of South China as a unique granite province globally. Within South Jiangxi, numerous metallic and non-metallic deposits have a close association with Mesozoic granite formations. The Kantian fluorite deposit, a newly discovered non-metallic deposit in southern Jiangxi Province, is one such deposit that is linked to Mesozoic granites. The orebody at the Kantian fluorite deposit is identified as occurring in veined structures within the silicification fracture zone of Mesozoic granites, with strict control exerted by fault systems. Fluorite ore can be classified into two categories based on the amount of quartz and fluorite. The first category is the fluorite quartz type, which has a higher amount of quartz than fluorite. The second category is quartz fluorite type, which has more fluorite than quartz. Among these two categories, the quartz fluorite type is precipitated during the primary mineralization stage. Through the analysis of fluid inclusions within the fluorite, it was determined that the homogenization temperature is relatively low, ranging from 133 to 236℃. The fluid inclusions also display low salinity (0.18–3.39 wt% NaCl eqv.) and low density (0.75–0.96 g/cm3). Laser Raman spectroscopy revealed that the primary components of the fluid inclusions are H 2 O, with minor C 3 H 6. Isotope analysis indicated δD VSMOW values of fluorite ranging from −61.9 ‰ to −54.8 ‰ (average −59.8 ‰), while δ18O VSMOW values varied from 1.3 ‰ to 3.1 ‰ (average 2.0 ‰). This study presents chronological, petrological and geochemical data that suggest several processes. The metallogenic age is 135.6 ± 0.7 Ma. The mineralizing fluids were identified to the NaCl-H 2 O system, with heated meteoric water identified as the primary source; The ore-forming materials originated from the granite, and water–rock interactions are proposed as the primary mechanism for fluorite precipitation. Based on a tectonic setting characterized by stretching, which is closely linked to the subduction of the Pacific plate, we proposed a model for the Kantian fluorite deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hydrothermal titanite associated with Au mineralization was formed at 130.8 ± 0.63 Ma. • The early Cretaceous Au mineralization overprinted the Triassic and late Jurassic Mo-Pb mineralization in Huangshui'an. • The gold precipitation mechanisms are sulfidation, collection-redissolution by LMCE melt, and changes in f Te 2 and f S 2. Huangshui'an deposit, situated in the Xiong'ershan area of Qinling orogenic belt (QOB) in China, is a globally rare carbonatite-type molybdenum polymetallic deposit that contains economic Mo, Au, Pb, and REE mineralization. The molybdenite Re-Os ages (Ca. 213.5–209.2 Ma) indicates that Huangshui'an Mo mineralization formed at Late Triassic. However, it is still unclear whether the Au mineralization is related to carbonatite dykes, and the formation age and genesis mechanism of Au mineralization remain poorly understood at Huangshui'an. This paper presents a comprehensive investigation of the Au mineralization events at the Huangshui'an deposit, including geology, mineralogy, and geochronology. The aim is to provide insights into its formation and mineralization processes and offer a broader understanding of regional Au metallogeny. Based on petrographic investigations, four stages are identified in the Au mineralization as follows: (I) quartz-K-feldspar stage; (II) quartz-pyrite-gold stage, including (IIA) pyrite-native gold sub-stage and (IIB) gold-tellurite-bismuthide sub-stage; (III) quartz-pyrite-polymetallic sulphide-oxide stage; and (IV) calcite-quartz-chlorite stage. The LA-ICP-MS titanite U-Pb dating yields a weighted mean age of 130.8 ± 0.63 Ma which determined that the Au mineralization at Huangshui'an was in the Early Cretaceous and was an independent mineralization event, which may be related to the lithosphere's destructive effect on the North China Craton (NCC). Combined with mineralography by automatic quantitative mineral analysis and testing system (TIMA), we consider that tellurium-bismuth minerals are closely associated with Au mineralization. The sulfur and tellurium fugacity of the ore-forming fluids in each stage were calculated using metal sulfide-oxides and tellurium-bismuth minerals. It was concluded that the precipitation of Au in the Huangshui'an deposit was mainly due to the combined effects of sulfidation, gold collection-redissolution by the low-melting point chalcophile elements (LMCE) melts, and the variation of sulfur fugacity and tellurium fugacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluid overpressure plays a key important role in the formation of skarn iron deposit. Skarn iron deposits are important resources for iron-rich ores and their genesis has been a topic of debate. The Nanminghe iron deposit is a typical skarn iron deposit in Wu'an, Hebei Province, China which provides a good example to investigate the metallogenic mechanism. In this paper, we present a detailed study of the geology, petrography, and geochemical characteristics of magnetite in the Nanminghe iron deposit. Two types of magnetite can be identified in the massive ores: Mag1 is euhedral with radial cracks developed in the margin. It is a low-Si magnetite, with SiO 2 content ranging from 0.07% to 0.92%, with an average value of 0.49%. The SiO 2 content of Mag2 is from 0.90% to 3.29%, and an average value of 2.03%. The Mag2 is associated with quartz, goethite, and apatite. Geochemical characteristics of Mag1, together with the ore textures suggest its crystallization from an iron magma. There are significant differences in the geochemical characteristics between Mag1 and Mag2. Mag2 is rich in Nb, Ta, high field strength elements, large ion lithophile elements and has higher silica content. The Nb/Ta of Mag2 is higher than that of the original mantle. These characteristics as well as La/Ta vs Th/La, Th/U vs Sm/Nd and Nb/Ta vs Nb features show that Mag2 is formed in the environment of supercritical fluids. The δ56Fe of Mag1 is 0.157‰-0.172‰, with an average value of 0.166‰, and the δ56Fe of Mag2 is 0.119‰-0.160‰, with an average value of 0.139‰. The Fe isotope of Mag2 is lighter than Mag1. There is a negative correlation between δ56Fe and SiO 2 of Mag1 and Mag2, suggesting that the lighter δ56Fe of Mag2 was caused by injection of Si-rich fluids. We propose a genetic model where we envisage that the iron-rich melt formed in the deep magma chamber by reaction of dioritic rocks and carbonates. Mag1 formed by cooling of the iron-rich magma, following which Si-rich supercritical fluid were injected into the deep chamber resulting in fluid overpressure. The iron-bearing melt-fluid migrated upward along the magmatic conduit, when Mag2 formed. Our study provides insights into the formation mechanism of skarn iron deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • The paleoclimatic conditions during deposition control the development of gray sandstone in the red beds. • The uranium mineralization in the red beds exhibits a certain correlation with the inorganic redox reactions involving iron. • Some dark mudstones in the red beds undergo a significant uranium pre-enrichment during deposition. • The climatic alternations lead to a weak reducing capacity in the red beds, with uranium mineralization occurring in the interior of the basin. The search for uranium deposits in the red beds is currently a hotspot in China's sandstone-type uranium exploration efforts. The typical occurrence of uranium deposits is within gray sandstone layers amidst the red beds, where the distribution of these gray sand bodies dictates the presence of uranium deposits. Hence, delving into the genesis of gray sandstone within the red beds proves beneficial for both uranium exploration and unraveling the ore-forming mechanisms. However, there is currently significant controversy surrounding the genesis of gray sandstone in the red beds. This paper focuses on the typical uranium deposit in the red beds—the HLJ-DL uranium deposit in the southwestern part of the Songliao Basin. It investigates the genesis of gray sandstone within uranium-bearing rock series and its relationship with uranium mineralization. The lithology of representative drill cores, including the red sandstone for comparative study, is methodically examined, along with their elemental geochemistry as well as carbon and oxygen isotope characteristics. The petrological characteristics suggest that both the gray and red sandstone share similar compositions of clastic particles, indicating minimal influence of the source rock on the sandstone color. The gray sandstone displays comparable TOC content (averaging around 0.05 %) and δ18O PDB values (averaging around −16 ‰) to the red sandstone. However, it exhibits relatively higher δ13C PDB values (averaging −0.26 ‰), whereas the average δ13C PDB value for the red beds is −1.61 ‰. The data indicate that the gray sandstone is less affected by hydrothermal or hydrocarbon fluids. Compared to the red sandstone, which has relatively higher Cu/Al values (averaging 1.09) and Fe3+/Fe2+ ratios (averaging 3.37), the gray sandstone exhibits low Cu/Al values (averaging 0.44) and a low Fe3+/Fe2+ ratio (averaging 0.36), suggesting its formation in a relatively reducing environment. The reducing conditions necessary for the formation of gray sandstone may stem from the climate becoming relatively warm and humid, irrespective of whether it originates from the original sedimentary environment or is induced by the reducing pore water discharged from dark mudstones. The chemical weathering index of fine-grained sediments indicates that, the gray sandstones were commonly configured in relatively humid-warm climate with fairly low dissolved oxygen content in the bottom water. Additionally, the deposition of the uranium-bearing rock series experienced alternating climatic changes, rather than consistently being in a humid-warm climate. This resulted in the sand bodies with low TOC content, insufficient reducing potential, and uranium mineralization primarily occurring in the interior of the basin. Organic matter has a relatively weak control over uranium mineralization, whereas uranium mineralization shows a certain correlation with iron reduction. The ore-forming fluid was uranium-rich oxygenated atmospheric water. Dark-colored mudstones, formed under humid-warm climatic condition, contain relatively high TOC contents (avg. 0.43 %) and exhibit a strong reducing capacity. The reducing pore water in dark-colored mudstones excreted into the adjacent sandstones under compaction during the early diagenesis, is able to serve as a vital reducing agent in later-stage uranium mineralization. Additionally, certain dark-colored mudstones with high uranium content (up to 944 ppm) undergo significant uranium pre-enrichment, providing a partial uranium source for uranium mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • The study investigates cobalt concentrations in catchment sediments/soils across China, and reveal geochemical baselines of cobalt for the first time. • Correlations are established between cobalt concentrations and different rock types, notably basic and ultrabasic rocks, as well as cobalt concentrations and hydrothermal and laterite cobalt deposits. • The research assesses the effectiveness of low-density geochemical mapping in indicating cobalt mineralization, offering insights into its representativity on a continental scale. • Findings serve as foundational information for further geological studies, mineral exploration, and establishing baselines for cobalt resource exploration and pollution assessment on a continental scale. Cobalt is an essential component of Li-ion batteries. Due to the rapid growth of the electric automobile market in recent years, the global demand for cobalt has surged to an unprecedented level. It is crucial to understand the concentration and distribution of cobalt on a continental scale. The China Geochemical Baselines project, conducted from 2008 to 2012, provides valuable insights into this issue. Catchment sediments/soils were sampled at a density of 1 site per 3000 km2 across most of mainland China, and cobalt concentrations were determined using inductively coupled plasma mass spectrometry. Cobalt concentrations in top sediments/soils (0–25 cm) range from 0.02 μg/g to 77.56 μg/g, with a median value of 10.99 μg/g. In deep sediments/soils (100–150 cm) cobalt concentrations range from 0.91 μg/g to 80.79 μg/g, with a median value of 10.62 μg/g. Cobalt concentrations in top and deep sediments/soils exhibit remarkable similarity, consistently reflecting variations in lithology types of exposed crust. This suggests that the cobalt in catchment sediments/soils is primarily inherited from the rocks. Cobalt distribution patterns in China are consistent with rock types. The conterminous distribution patterns of high background concentrations falling in the Q75-Q85 range are mainly controlled by basic and ultra-basic rocks such as basalts and ophiolites. Sporadic anomalies beyond Q85 strongly correlate with hydrothermal and laterite cobalt deposits, but show weak correlation with magmatic cobalt deposits. This paper provides fundamental continental-scale information for further geological study and mineral exploration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phlogopite 40Ar–39Ar dating constrains the age of the Baijian deposit at ca. 128 Ma. • Magnetite and its equilibrated fluid acquire high δ18O values through fluid-wall rock interaction. • Interaction of magmatic fluids with evaporate-bearing carbonates may play a vital role in the district-wide Fe skarn mineralization. The Handan-Xingtai district, situated in the central part of the North China craton, is one of the most important concentrations of Fe skarns in China. Baijian is the largest Fe skarn deposit in this district with significant Fe reserves being newly identified. This deposit is spatially related with a monzodiorite stock intruding the Middle Ordovician evaporate-bearing marine carbonates, with Fe mineralization occurring in the contact zone or within carbonate wall rocks. This paper conducts a comprehensive investigation encompassing geological, mineralogical, geochronological, and stable isotope analyses of the Baijian deposit. The goal is to provide insights into its formation and mineralization processes and offer a broader understanding of regional Fe metallogeny. The skarn mineralogy in the Baijian deposit is predominantly characterized by Mg-rich minerals such as diopside, tremolite, serpentine, and phlogopite. Magnetite is the dominant metallic mineral, featuring low Ti contents (<0.11 wt%) and high Fe concentrations (>66.59 wt%), indicative of a hydrothermal origin. The majority of the magnetite trace element data are plotted in the skarn field on the Al + Mn versus Ti + V diagram. Pyrite, a notable component in ores, exhibits considerable variations in Co and Ni concentrations, with Co/Ni ratio generally higher than unity. Phlogopite 40Ar–39Ar dating constrains the formation of the Baijian Fe skarn deposit at ca. 128 Ma, aligning with zircon U-Pb ages (128.8 ± 0.9 Ma) of the associated monzodiorite. This temporal congruence suggests a genetic relationship between the magmatism and skarn mineralization. Combined with previous published geochronological data, this study identifies an increasing trend in Fe mineralization intensity within the Handan-Xingtai district, spanning from ca. 137 to 128 Ma. Geological and oxygen isotopic evidence advocates for a magmatic origin of the ore-forming fluids at the Baijian deposit. The δ18O values of these fluids experience elevation through interaction with carbonate wall rocks. The pronouncedly high δ34S values of pyrite (>16.1 ‰) in the Baijian magnetite ores underscore a substantial sulfur contribution from sulfate in evaporate beds. Drawing on geological, mineralogical, and isotopic evidence, the study suggests that the interaction between magmatic fluids and evaporate-bearing carbonate rocks plays an important role in magnetite precipitation at the Baijian deposit. This interaction serves to reduce fluid acidity and facilitate the oxidation of ferrous iron (Fe2+). The Fe skarn deposits in Handan-Xingtai district are mostly hosted in middle Ordovician evaporite-bearing carbonate strata with ore-related sulfides exhibiting strong 34S enrichment (δ34S > 10 ‰). The interaction of magmatic fluids with evaporate-bearing carbonates is likely a common process responsible for magnetite deposition in the Fe skarn deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • The bitumen in wall rocks and the Danzhai paleo-oil reservoir both originate from the Lower Cambrian source rock. • The paleo-oil reservoir and the ore sulfur both derive from seawater sulfate in the strata. The metallogenic metals are mainly sourced from the underlying strata and basement. • Bitumen Re-Os and sphalerite Rb-Sr isotopes yield isochron ages of 424±160 Ma and 398±4.7 Ma, respectively. • Hydrocarbons supply a large amount of reduced sulfur for mineralization through TSR reaction. The Niujiaotang MVT Pb-Zn ore field is located at the southwestern end of the West Hunan-East Guizhou (WHEG) metallogenic belt, which overlaps spatially with the Majiang paleo-oil reservoir. The Pb-Zn mineralization is closely associated with oil-gas accumulation processes. However, the genetic link between the paleo-oil reservoir and the Pb-Zn deposits remains unclear. In this paper, we present new findings of bitumen (paleo-oil reservoir) and its features in the deposits, and apply various isotopic geochemical methods and 2D seismic data to elucidate the source rock and coupling relationship of the paleo-oil reservoir and the Pb-Zn deposits. This study reveals that the ore has a simple mineral composition, mainly comprising sphalerite, pyrite, and dolomite. Solid bitumen occurs widely in the ore and the host dolostone, and coexists with minerals from the mineralization stage. Laser Raman spectroscopy shows that the bitumen in the wall rocks of the Chengong deposit and the Danzhai paleo-oil reservoir are both overmature, and their carbon isotope compositions (δ13C PDB = –29.17 ‰ – –31.20 ‰, average –30.10 ‰, n = 6) and initial 187Os/188Os ratio (1.08±0.19) suggest that they have the Lower Cambrian source rock similar to the Majiang paleo-oil reservoir. The δ34S value of pyrite in the bitumen from the wall rocks in the Chengong deposit ranges from +28.15 ‰ to +44.12 ‰ (average +33.28 ‰, n = 18), which is consistent with the sulfur isotope composition of the ore sulfide reported previously, indicating that they both derived from sulfate in the Middle-Upper Cambrian strata. Bitumen Re-Os and sphalerite Rb-Sr isotopic dating indicate that oil reservoir accumulation in the ore-hosting strata preceded Pb-Zn mineralization, occurring at 424±160 Ma (MSWD = 1.3) and 398±4.7 Ma (MSWD = 0.66), respectively. The initial 87Sr/86Sr ratio of sphalerite is 0.709983±0.000027, which, after comparison and in combination with previous studies, suggests that the metallogenic metals mainly originated from the underlying strata and basement. 2D seismic data show that the Zaolou fault (F 2) that controls the mineralization is a deep fault that extends to the basin basement, and acts as a migration pathway for hydrocarbon fluids and ore-forming materials. We propose that liquid hydrocarbons played a significant role in Pb-Zn mineralization, acting as reductants to reduce sulfate through the thermochemical sulfate reduction (TSR) reaction and provide abundant reduced sulfur (H2S/HS−) for Pb-Zn mineralization. Finally, we present a comprehensive model of hydrocarbon accumulation and mineralization in the Niujiaotang ore field. [ABSTRACT FROM AUTHOR]

[Display omitted] • The volcano-plutonic complex was mainly generated by the partial melting of lower crust. • Mantle delamination generated heterogeneous magma and thus a variety of deposits. • Intracontinental tectonic transformation controlled the porphyry emplacement. The Yao'an Pb–Ag–Au deposit is located far from the present-day margin of the Yangtze Craton, providing an excellent example for studying the genesis of porphyries and associated polymetallic mineralization in intracontinental transpression settings. In situ zircon U–Pb ages and Sr–Nd–Hf–O isotopic data of the Yao'an porphyries in the intracontinental zone, combined with research data published for the Machangqing and Beiya ore-bearing porphyries in the cratonic margin, were used in this paper. Four-phase felsic rocks (∼33 Ma) and later mafic rock (∼31 Ma) were recognized in the Yao'an district. Of these, the third-phase syenite porphyry had a genetic link with Pb–Ag–Au mineralization, which occurred within the second-phase volcanic rocks and Mesozoic strata. In addition, the Yao'an porphyry showed high initial 87Sr/86Sr ratios (0.7087–0.7094) and enriched Nd (ε Nd (t) = −10.53 to −12.60) isotopic composition, with a wide range of zircon Hf (ε Hf (t) = −8.39 to −13.2) and δ 18O values (6.28 ‰–9.20 ‰). These features suggest that the Yao'an porphyries were produced by partial melting of an ancient lower crust mixed with continental lithospheric-mantle-derived melt, which are differed from the magma source of the Beiya and Machangqing porphyries. Given the nature sources of the porphyries, we conclude that the spatial variation of metal associations changing from the Cu ± Au ± Mo system at the cratonic margin to the Pb–Ag–Au deposits in the intracontinental zone in the western Yangtze Craton was likely controlled by different magma sources. The delamination of an overthickened continental lithospheric mantle in an intracontinental transpression setting was a geodynamic trigger for porphyry magma generation, ascent, and emplacement. [ABSTRACT FROM AUTHOR]

[Display omitted] • Early Late Cretaceous Au mineralization in NE China. • Mantle contribution for Early Late Cretaceous Au mineralization. • Driven by the westward subduction of the Paleo-Pacific oceanic slab. The age and petrogenesis of volcanic–subvolcanic rocks associated with Au mineralization of the recently discovered Yidonglinchang Au deposit in the Lesser Xing'an Range provide insights into late Mesozoic Au metallogenesis in NE China. In this paper, we report zircon U–Pb chronological and Hf isotopic, whole–rock geochemical, and Sr–Nd isotopic data of the andesite porphyry and quartz diorite porphyry from the Yidonglinchang Au deposit. Zircon U–Pb dating shows that the andesite porphyry and quartz diorite porphyry associated with Au mineralization were formed at 101 and 99–97 Ma, respectively, suggestive of an early Late Cretaceous Au mineralization event in the Lesser Xing'an Range. Whole–rock geochemical data reveal that they have low SiO 2 contents (59.87–61.48 % and 55.91–63.22 %, respectively) and high Mg# values (41.5–55.4 and 43.2–61.3, respectively). In addition, these rocks are enriched in large–ion lithophile elements (e.g., K, Rb, and Ba) and depleted in high–field–strength elements (e.g., Nb, Ta, P, Ti, Zr, and Hf). The rocks have slightly negative to positive zircon ε Hf (t) values (−2.3 to 5.7) and negative whole–rock ε Nd (t) values (−3.3 to −2.9), indicating a metasomatized mantle source with some contamination by crustal materials. Combined with regional magmatic and metallogenic characteristics, we conclude that the Au mineralization at Yidonglinchang formed as a result of early Late Cretaceous magmatic–hydrothermal activities. Previously obtained data show that the orogenic Au deposits in the northern NE China formed mainly during the Early Cretaceous, earlier than the late Early Cretaceous to Late Cretaceous epithermal Au deposits in the eastern NE China. The formation of the late Mesozoic Au mineralization in the northern and eastern NE China was likely controlled by distinct tectonic settings. During the late Early to early Late Cretaceous, the rollback of Paleo–Pacific oceanic slab beneath eastern NE China generated an extensional setting that led to large–scale magmatism and associated Au mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pianyanzi area in western Sichuan hosts a rare sellaite-bearing orogenic gold deposit. • Gold is mostly present as visible native gold formed in two stages. • Gold precipitation was forced by interaction between auriferous fluids and wall rocks. • Metasomatized mantle lithosphere served a potential source of ore fluids. The Pianyanzi gold deposit is situated at the western margin of the Yangtze Craton, and represents a rare sellaite-bearing orogenic gold deposit. This deposit belongs to the Dauduhe gold belt of southwestern China and remains poorly documented. In this paper we present first petrographic and in-situ geochemistrical and sulfur isotope data from pyrite as well as results of multielement mapping. The deposit is dominated by native gold (average gold fineness = 980.8) filling fractures in minerals (e.g., pyrite, quartz, sellaite and hematite) or also emplaced along the contact interface between mineral grains. Pyrite is the most abundant sulfide mineral of this deposit. We identified five generations of pyrite: Py1, Py2a, Py2b, Py3, and Py4. Gold occurs in sellaite- and hematite-bearing mineral assemblages formed simultaneous with the formation of Py2a&b and Py4, respectively. Py1 formed in the Au-poor ore stage, while Py3 formed during the late galena-dominated sulfide stage. All generations of pyrite exhibit low concentrations of gold with an average value of less than 2 ppm. Py2a&b possess distinctive textures and chemical zonation, with trace elements displaying greater variations compared to Py1, Py3 and Py4. The δ34S values vary from −0.52 ‰ to 7.08 ‰, which is consistent with those of orogenic deposits of the Daduhe gold belt. The deep metasomatized mantle lithosphere acted as a potential source of ore fluids. We conclude that the co-precipitation of native gold and sellaite was triggered by the interaction between auriferous fluids and dolomite. [ABSTRACT FROM AUTHOR]

• Types and temporal-spatial distribution of W and Sn mineralization in South China are summarized based on over 130 major deposits. • Metallogenic models illustrating the combination of diverse mineralization styles or metal assemblages are proposed for W-Sn deposits in South China. • Fluid and melt inclusion compositions are tested as new index to evaluate W and Sn mineralization potential in granitic system. South China is one of the most important tungsten-tin metallogenic areas in the world. Based on the up-to-date geological and chronological data of more than 130 deposits of economic significance, this paper preliminarily summarized the main types and temporal-spatial distribution characteristics of the large-scale tungsten and tin mineralization related to granite in South China. The statistical results show that skarn and quartz-vein types are the most important tungsten metallogenic styles, while skarn and cassiterite-sulfide types are the most important tin metallogenic styles in South China. Tungsten and tin mineralization related to granite in South China are multi-aged, but the largest scale of mineralization is developed within the Yanshanian period. Tungsten mineralization, the majority of which represented by the Nanling and Ganbei metallogenic belts, mainly formed from the Late Jurassic to Early Cretaceous (160 ∼ 120 Ma), while the most important tin mineralization formed in the Late Cretaceous (110 ∼ 80 Ma, peaking at 90 ∼ 80 Ma) and Late Jurassic (160 ∼ 150 Ma) as represented by the Youjiang Basin and Nanling metallogenic belt, respectively. The combined occurrence of different mineralization styles or metal assemblages in individual deposit and sometimes within the same orefield is the most striking feature of granite-related tungsten-tin deposits in South China, and a comprehensive understanding of their patterns are of great significance to guide ore prospecting. To address this issue, this paper proposed several combined metallogenic models and prospecting directions for tungsten-tin mineralization in South China based on recent researches and exploration progresses from typical examples including the Yaogangxian, Chuankou, Maoping, Shizhuyuan, Dachang and Gejiu deposits or orefields. In addition, conventional petrological and mineralogical characteristics that differentiates tungsten and tin granites are summarized, and on this basis the chemical composition of both melt inclusion and early stage fluid inclusion from granitic magmatic-hydrothermal systems were tested as new index to evaluate the tungsten and tin mineralization potential of granitic system. [ABSTRACT FROM AUTHOR]

In recent years, many concealed skarn-type and porphyry-type deposits have been discovered in Chating area, which shows very good prospectivity to host hydrothermal deposits. In this paper, we carried out the 3D mineral prospectivity modeling for porphyry and skarn-type mineralization of the Chating area. During this study, implicit geological modeling and the "total litho-inversion" method were used to build the 3D geological models and optimize the 3D geological models, various 3D predictive maps were generated by multiple 3D methods according to the exploration model. Finally, we use a 3D convolutional neural network (3D CNN) model to integrate all of the 3D predictive maps and delineate the concealed targets. The results show that the high- prospective areas delineated based on the 3DMPM not only include the deposits which are used as training data, but also the deposits that have already been discovered in the study area. It means that the 3DMPM approach used in this paper has good prediction and generalization ability. Compared with the Logistic Regression model (LR), Support Vector Machines (SVM), and Radom Forest (RF) model, the 3D CNN model can efficiently capture the correlation between various deposit types and 3D predictive information, and has better commendable predictive capabilities. The results of this paper can not only provide some new highly prospective areas for further mineral exploration in Chating area but also can promote the research on 3DMPM with deep learning methods. [Display omitted] • 3D Convolutional Neural Network would provide a new and powerful tool for 3D mineral prospectivity modeling. • The "total litho-inversion" method is a viable tool for the optimization of the 3D geological models which can provide more reliable data for 3D mineral prospectivity modeling. • 3D mineral prospectivity modeling can effectively identify not only the known deposits (not training data), but also delineate several new favorable exploration areas within Chating area at depth. The Chating area is situated within the Middle-Lower Yangtze River Metallogenic Belt, China. Several concealed skarn and porphyry-type deposits have been discovered in this area, indicating high potential for hosting hydrothermal deposits. However, due to the complex geological structure, exploration risks significantly increase with increasing depth. To overcome this challenge, three-dimensional mineral prospectivity modeling (3DMPM) has begun to be widely applied for mapping the prospectivity of deep-seated and concealed mineralization. However, most previous studies on 3DMPM were based on shallow supervised machine learning models and dimensionality-reduced 3D predictive maps. Although these models have shown good results, they may lose spatial correlation within the 3D predictive maps and fail to explore nonlinear correlations between the 3D predictive maps and mineralization. Meanwhile, 3D geological models are the most important basis of the 3DMPM, however, in the past, few studies have incorporated the optimization of the 3D geological models into the process of 3DMPM. Therefore, this paper initially builds and optimizes 3D geological models through implicit 3D geological modeling and "total litho-inversion" approach. Subsequently, the 3D predictive maps are generated by employing various 3D methods, which are further integrated using a 3D convolutional neural network (3D CNN) model to identify highly prospective areas for mineralization. The results show that the highly prospective areas identified by the 3DMPM include not only the training data but also other mineral deposits that have previously been discovered within the study area. In addition, compared with the Logistic Regression model (LR), Support Vector Machines (SVM), and Radom Forest (RF), the 3D CNN performs better prediction capabilities due to its enhanced ability to capture the correlations between 3D predictive maps and multiple types of mineral deposits. It suggests that the 3DMPM based on the 3D CNN model has commendable predictive capabilities in identifying prospective mineralization areas, and some new highly prospective areas can be considered as priority areas for future exploration of concealed mineralization within the Chating Area. [ABSTRACT FROM AUTHOR]

[Display omitted] • The granodiorite porphyry in the Xiayi Sn deposit formed at 138 Ma, determined by zircon U-Pb dating. • Cassiterite U-Pb dating indicates a Sn mineralization age of 136 Ma in the Xiayi Sn deposit, which is contemporaneous with the granodiorite porphyry. • Hf isotope analysis of zircon suggests the involvement of mantle materials during the formation of the granodiorite porphyry. • Trace element compositions of cassiterite reveal distinct roles of Ti, W, Fe, V, and Sc in the cathodoluminescence (CL) response. • Our research provides valuable insights into the extension of the southeastern coastal metallogenic Sn belt into western Fujian Province. The Xiayi Sn deposit, located in the Sanming city, southeast China, is the largest Sn deposit in Fujian province. The mineralization mainly consists of cassiterite-bearing veinlets and stockworks, and it is spatially associated with the granodiorite porphyry. Despite its economic significance, few studies have been carried out, and the mineralization age remains unknown. In this paper, we present the first geochronological data on the cassiterite and the associated granodiorite porphyry, Hf isotope of the zircon, and trace element compositions of cassiterite from the Xiayi Sn deposit. These data give precise age of the Sn mineralization and constrain its relationship with the granitic intrusion. Zircon U-Pb dating of the ore-related granodiorite porphyry yielded the age of 138.3 ± 1.8 Ma, which agreed well with the cassiterite U-Pb age of 136.5 ± 1.4 Ma, documenting the genetic link between the Sn mineralization and granitic magmatism. Zircon εHf(t) ranged from −4.5 to −1.8 with a weighted mean of −3.4 and the Hf model ages (TDM2) vary from 1.31 to 1.47 Ga with a mean value of 1.40 Ga. These data indicate that the granodiorite porphyry originates from the partial melting of the crustal materials of Mesoproterozoic basement and show the addition of mantle-derived materials, similar to typical Sn mineralized granite in the southeastern coastal tin belt and Nanling tungsten-tin belt. Besides, cassiterite from Xiayi deposit show clear CL-bright and CL-dark sector zonation in the cathodoluminescence images. LA-ICP-MS trace element analyses of cassiterites indicate a high Ti and Fe but low Nb and Ta contents in both CL-bright and CL-dark sector zones, while the W content is significantly high in the CL-dark zone and low in the CL-bright zone. Cassiterite trace element compositions together with the mineralization pattern and alteration assemblages indicate that Xiayi is a porphyry tin deposit. These results provide proof of the extension of the southeastern coastal Sn metallogenic belt and offer potential breakthroughs in tin deposit exploration in southwestern Fujian Province. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb dating results refine the emplacement age of the Xikeng pluton at 232.2 ± 1.1 Ma. • Cassiterite and wolframite U-Pb dating constrains the timing of W-Sn mineralization from Xigkeng deposit at 228.4 ± 0.90 Ma and 227.8 ± 1.60 Ma, respectively. • Source of magmatic materials was derived from reworking of crustal materials under an extensional setting. The Chongyi–Shangyou–Dayu ore-concentrated district represents one of the most important wolframite production bases in China, and most of the W-Sn deposits formed in the early Yanshanian period. The Xikeng quartz vein-type W-Sn deposit is located spatially not far from the Triassic Keshuling granitic pluton. The deposit contains 43 ore-bearing quartz veins, in which the ore minerals are mainly cassiterite and wolframite. These ore veins are concentrated in the Sinian metasandstone and sandy slate of the Laohutang Formation and extend down to the top of the concealed granite. The concealed intrusion is composed of medium- to fine-grained muscovite granites, which relate to the Indosinian Keshuling granite, according to geophysical data. Zircon grains from the concealed Xikeng granitic intrusion have a concordant U-Pb age of 232.1 ± 1.1 Ma (MSWD = 0.9). The zircon εHf(t) values range from −11.0 to −7.9, indicating primary reworking of the ancient crustal materials. Wolframite and cassiterite grains yield Tera-Wasserburg concordia intercept ages of 228.4 ± 0.9 Ma (MSWD = 1.2) and 227.8 ± 1.6 Ma (MSWD = 0.3) for the Xikeng deposit, respectively. These data demonstrate that the Indosinian W-Sn mineralization events were genetically related to granitic magma activities that share similar magmatic sources with the Yanshanian W-Sn mineralization-associated granitic intrusions. Combined with previous robust granitic and metallogenic ages, this paper identifies a new Indosinian W-Sn mineralization event in southern Jiangxi Province, Nanling Range. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Langwashan iron deposit in submarine volcanic rocks is a Fe-skarn deposit. • Magnetite properties indicate iron mineralization and hydrothermal processes. • Many submarine volcanic iron deposits are likely to be Fe-skarn deposits. Carboniferous submarine volcanic rocks hosting iron deposits are widely distributed in the Tianshan and Beishan orogenic belts. However, the genesis of these deposits remains unresolved, with contrasting magmatic and magmatic-hydrothermal models being proposed. The Langwashan iron deposit (83.18 Mt @ 37% Fe) is one of the largest iron deposits in the Beishan orogenic belt. In this paper, we present detailed textural and trace-elemental properties of magnetite from the Langwashan iron deposit to elucidate the genesis and evolution of iron mineralization hosted in Lower Carboniferous submarine volcanic rocks. The Langwashan iron deposit has various types of iron ore that are closely associated with skarn minerals, including garnet and epidote. Magnetite in these samples can be classified into two distinct types, early-stage mushketovite (Mag1) and late-stage granular magnetite (Mag2), both of which show oscillatory zoning, with low Ti (mean of 0.03–0.07 wt%) and V (mean of 0.03–0.04 wt%) contents, and variable Si contents (mean of 0.74–6.50 wt%). These textural and compositional data classify the Langwashan deposit as a typical Fe-skarn deposit. Results also reveal that iron oxides in the Langwashan deposit underwent a complex evolution comprising three episodes: (1) early-stage influx of low-oxygen-fugacity, calcium-rich hydrothermal fluids, causing the transformation of original hematite to mushketovite (Mag1-1) and the formation of scheelite inclusions; (2) subsequent dissolution–reprecipitation between high-temperature magmatic-hydrothermal fluids and Mag1-1, generating trace-element-rich mushketovite (Mag1-2) and the precipitation of trace-element-rich granular magnetite (Mag2-1) from magmatic-hydrothermal fluids; and (3) final multiple fluid metasomatism under the influence of trace-element-poor hydrothermal fluids, involving dissolution–reprecipitation that produced trace-element-deficient Mag1-3, Mag2-2, and Mag2-3. Results also highlight that the submarine volcanic iron deposits from both the Tianshan and the Beishan orogenic belts were probably formed in a similar geological setting, with similar timing of formation, mechanism of mineralization, and evolution, and they are likely Fe-skarn deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nam Xe REE deposit is of hydrothermal origin. • Nam Xe REE deposit has two episodes of REE mineralization at 45–44 Ma and 35–31 Ma. • Two episodes of REE mineralization coincide with the main- and late-collisional periods of the India-Asia convergence, respectively. Carbonatite-related rare-earth element (REE) deposits are developed in large areas of southwestern China and northwestern Vietnam on the SW margin of the South China block. The ages of REE deposits and their host carbonatite-alkaline rocks in southwestern China have been tightly constrained in the 35–10 Ma interval, but those in northwestern Vietnam remain poorly understood. In this paper, we present new Th–Pb dating results to constrain the timing of mineralization of the Nam Xe REE deposit in northwestern Vietnam, and to reveal its possible relationship to the well-studied REE deposits in southwestern China. The Nam Xe deposit consists of three types of REE ores: Type 1, fine-grained disseminated ores; Type 2, coarse-grained, taxitic ores; and Type 3, REE veinlets. The mineral assemblages and their close relations to hydrothermal alteration, combined with the trace element patterns of the ore minerals, indicate a hydrothermal origin for all the three ore types. Laser ablation-inductively coupled plasma-mass spectrometry Th–Pb dating of monazite yielded weighted-mean Th–Pb ages of 45–44 Ma for type 1 ores and 35–32 Ma for type 2 and 3 varieties, whereas the LA-ICPMS dating of bastnäsite has ages of 35–31 Ma for types 2 and 3, revealing two REE mineralization events at 45–44 and 35–31 Ma in the Nam Xe deposit. The age of type 1 ores overlaps the main-collision period of India-Asia collisional orogeny (65–41 Ma) which confirms carbonatite-related REE mineralization could form in the main-collisional geological setting. The ages of types 2 and 3 ores are consistent with those of the Mianning–Dechang REE metallogenic belt in southwestern China that formed under a late-collision extensional setting (40–26 Ma). Combined with existing geochronological data, results presented here suggest that the Nam Xe REE deposit formed both in the main- and late-collisional settings and represents the southern extension of the Mianning–Dechang REE metallogenic belt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Expression of geological map information in the form of knowledge graphs to shown regional geological characteristics and connections. • Using the knowledge embedding method to embed the geological map knowledge in order to show the mineralization characteristics. • Knowledge and geochemical data was aligned in space by knowledge embedding gridding to realize the forward integration of knowledge and data, and to realize bi-directional knowledge and data-driven mineral prospectivity. The knowledge graph in geological applications is highly regarded, and its usefulness requires the support of geological survey data. Therefore, this paper proposes a mineral prospectivity mapping (MPM) method that integrates geological map knowledge graphs with geochemical data. The geological map knowledge graph is used in the vectorized form as knowledge features in the training of the mineral prediction model. It is also used for knowledge-based ore-forming interpretation of prospective areas, achieving bidirectional application of knowledge in prediction and interpretation of prediction results. Unlike most knowledge graphs, the geological map knowledge graph represents spatial correlations and geological features in the form of "entity-relation-entity" triplets, with geological map units as entities and assigned geological attributes. Based on this, an MPM process driven by knowledge graph and data is proposed: (1) Convert the geological map knowledge graph into low-dimensional vectors using node2VEC. (2) Align geological knowledge with geochemical data spatially through knowledge embedding gridization, achieving a forward fusion of knowledge and data. (3) Collect the integrated data using window sampling as the training dataset for DenseNet to train the mineral prospection model. A case study was conducted to demonstrate the advantages of the method for producing a potential map linked to gold mineralization in the Rao Feng area, Shaanxi Province, China. The results show that the prospective areas with knowledge graph embedding and geochemical data are better and delineate six unmineralized prospective areas. Ore-forming interpretations based on knowledge graph information were conducted on the prospective areas, demonstrating strong consistency between the ore-forming geological features of the prediction areas and known mineral deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Most components of polymetallic deposit occur in the HF-soluble silicate assemblages. • Approximately 89% of Zr is hosted in zircons of varying grain size. • The SCEP results strongly do not support the previous hypothesis that incompatible elements are adsorbed by clay minerals. • The incompatible elements can replace K, and/or Si, and/or Al in the clay crystalline structure. Altered volcanic ash with highly-elevated concentrations of Nb(Ta), Zr(Hf), Ga, and rare earth elements and yttrium (REY) is an untraditional type of critical metal deposit that has been discovered in Yunnan Province, southwest China. Previous studies have briefly described the modes of occurrence of Nb(Ta)-Zr(Hf)-REY-Ga in the ore deposit, showing that Zr and Hf are mostly hosted in zircon; light rare earth elements (LREE) mainly occur in REY-bearing carbonates and phosphates; Nb and Ta are primarily hosted in the former Fe-Ti oxide phases and zircon; and Ga is predominantly associated with clay minerals. However, previous studies of the modes of occurrence of critical metal elements (Nb-Ta-Zr-Hf-REY-Ga) have been limited to qualitative or semi-quantitative studies of individual mineral grains, and quantitative research of the modes of occurrence of these elements in whole rocks is absent. This paper quantifies the modes of occurrence of critical elements (Nb-Ta-Zr-Hf-REY-Ga) using a sequential chemical extraction method. The results show that about 65.3–86.7% Nb is associated with hydrofluoric acid (HF)-soluble aluminosilicates (clays) and 13.3–34.7% in the insoluble phases such as Nb-rutile. Approximately 87.6–90.2% Zr is the primary hosted in zircon and 9.5–12.0% Zr appears to be associated with HF-soluble aluminosilicates in the altered volcanic ash. In felsic altered volcanic ashes (Al 2 O 3 /TiO 2 ratio between 21 and 70), the REY are predominantly in the authigenic minerals such as REY-bearing aluminum phosphates and sulfates of the alunite supergroup (APS minerals), carbonates or fluorocarbonates. About 74.0–89.4% LREE, 26.5–34.2% middle rare earth elements (MREY), and 22.1–24.8% heavy rare earth elements (HREE) occur in HF-soluble aluminosilicates. In intermediate altered volcanic ash samples (Al 2 O 3 /TiO 2 ratio between 8 and 21), 93.0% LREE are associated with insoluble phases such as monazite and zircon. Gallium is predominantly associated with HF-soluble aluminosilicates (73.3–80.5%) in all altered volcanic ash samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Li mostly occurs as adsorption or ion exchange in clay minerals. • The depositional environment of the No. 2 coal alternates between a hydrostatic reducing condition and an anoxic reducing environment. • Multiple geological effects influence the dissolution and migration of element-enriched minerals, resulting in the enrichment of stable components. In order to study the enrichment mechanism and depositional environment of valuable elements, this paper reports new geochemistry and mineralogy data on the No. 2 and No. 5 coals of the Nangou Mine, Ningwu Coalfield. Clay minerals and calcite are the dominant minerals in both the No. 2 and No. 5 coals. Additionally, small amounts of pyrite, quartz, rutile, and zircon are observed under scanning electron microscopy in the No. 5 coal. The studied coals in Nangou Mine are enriched in Li (CC = 8.50 and 5.80, respectively in the No. 2 and No. 5 coal), Zr (CC = 21.87 and 5.53), Nb (CC = 16.97 and 2.54), Hf (CC = 14.00 and 4.19), Ga (CC = 2.56 and 2.41). Li mostly occurs as adsorption or ion exchange in clay minerals, Nb, Zr, Hf, and Ga have organic affinities, rare earth elements and Y are mostly found in residue and organic binding states. The sediment source of the Nangou Mine is characterized by a multi-source area, with the dissolution and migration of element-enriched minerals under the influence of multiple geological effects, leading to the enrichment of valuable elements (Li, Nb, Zr, Ga, and REY). [ABSTRACT FROM AUTHOR]

Due to the strong variations in the distribution of the sedimentary strata, the degree of denudation of carbonate strata is not consistent across the different regions. In the Huanglong ore field, the carbonate strata hosting the Longqiao ore body is relatively stable, and its protolith comprises dolomitic limestone and dolomitic marlstone, whereas the lithology of that hosting the Mabianshan ore body shift from Fe-Mn bearing dolomite and dolomite to dolomitic limestone and marlstone in the extension direction of the ore body. The content of Al, Si, Mg, Mn and Ca in the carbonate strata in Mabianshan varies more greatly in this direction. [Display omitted] • The Mabianshan and Longqiao deposits in Luzong volcanic basin had different heat sources. • The protolith of Mabianshan magnetite ore body varies greatly in the content of Al, Si, Mg, Mn, and Ca. • The complex protolith lithology of magnetite results in tracing fluid source using Si, Al, Mg, and Mn hard to effectively. The composition of host rocks is essential in determining the composition of hydrothermal magnetite formed via fluid-rock interactions in skarn deposits. The HuangLong ore field in the Luzong volcanic basin, Eastern China, hosts several stratabound iron (Fe) skarn deposits, including Mabianshan and Longqiao. In this paper, we analyse the composition of different lithologies of carbonate strata and trace element concentrations in magnetite from Mabianshan, which has complex lithology carbonate strata, and compare it with magnetite from Longqiao, which has uniform lithology carbonate strata. The objective is to investigate the influence of lithology variation on magnetite trace elements and enhance the indicative significance of magnetite trace elements in prospecting and exploration. Our results demonstrate that the lithology of ore-bearing carbonate strata varies greatly due to inversion and different degrees of denudation in the ore field, resulting in variations of Al, Si, Mg, Mn, and Ca in the protolith across different areas. The alteration mineral assemblage of the Mabianshan deposit primarily included epidote, chlorite, and magnetite, while only a few diopside-magnetite relatively high-temperature assemblages developed in the southeastern part of the deposit. Moreover, higher concentrations of Ti and V in magnetite samples from the southeastern area of the deposit suggest that the heat sources related to Fe mineralization may be located there. Compared with the regular spatial variations of Mg, Mn, Al, and Si in the magnetite from Longqiao, the magnetite from Mabianshan does not show evident spatial variations due to the complex lithology of the magnetite protolith in different regions. The protolith lithology of magnetite from Longqiao is relatively stable, mainly dolomitic limestone. However, the protolith lithology of magnetite from Mabianshan is complex and includes dolomitic marlstone, dolomitic limestone, dolomite, and Fe-Mn bearing dolomite, resulting in a significant increase of Si, Al, Mg, and Mn in magnetite. Therefore, it is difficult to effectively trace the temporal-spatial evolution of the hydrothermal fluids using these elements in magnetite. Special attention should be paid to the uniformity of the protolith lithology of the ore when using these elements in magnetite to trace the fluid source. [ABSTRACT FROM AUTHOR]

[Display omitted] • The genesis of the Fenghuangshan gold deposit is considered to be magmatic-hydrothermal. • The Fenghuangshan gold deposit is related to the Paleo-Pacific plate subduction. • The study area is highly prospective for deep-seated gold mineralization. The Jidong area is a vital gold province in North China, including plenty of metamorphic rock-hosted gold deposits. Whether ore-forming fluids are magmatic or metamorphic remains controversial. The genesis for gold mineralization in this gold province is ambiguous. The Fenghuangshan gold deposit lies on the eastern fragment of the Jidong gold province. In this paper, we present a detailed study on ore geology, fluid inclusions, and stable isotopes for the deposit to illustrate the characteristics of ore-forming fluids and ore genesis. The deposit occurs as gold-bearing quartz vein and disseminated- and veinlet-type mineralization. The main orebody named 7# is hosted in migmatitic granite, controlled by NE trending secondary fracture system. Four hydrothermal mineralization stages were identified, including: (Ⅰ) white quartz, (II) pyrite-quartz, (III) quartz-polymetallic sulfide, and (IV) calcite-chlorite-quartz. The Stage II and III belong to main gold mineralization stage. Fluid inclusions from different stages show that a lowering trend of fluid inclusion homogenization temperature was observed. They ranged from 222 °C to 407 °C (early-stage), 144 °C to 375 °C (main-stage), and 86 °C to 174 °C (late-stage), respectively. The salinities of the ore-forming fluids were typically low, ranging from 0.83 to 15.47 wt% NaCl equivalent. On the basis of Laser Raman analysis and fluid inclusion microthermometry, the ore-forming fluids belonged to a low- to moderate-temperature, low-salinity H 2 O-NaCl-CO 2 system. Fluid immiscibility gave rise to rapid gold deposition. The early-stage δD and δ18O H2O values from quartzs ranged from –96.4‰ to –92.5‰ and from 1.74‰ to 2.44‰, whereas main-stage fluids had δ18O H2O values of –4.10‰ to –3.50‰ and δD values of –91.5‰ to –89.5‰. The early- and main-stage sulfide δ34S values varied from –2.0‰ to + 2.2‰, with average values of + 0.4‰. H-O-S-isotope data indicated that the primary ore-forming fluids were magmatic water mixing meteoric water during mineralization, and ore-forming materials were derived from a homogeneous magmatic source. Ore geology, fluid inclusions, and stable isotopes illustrate that the Fenghuangshan gold deposit is a low- to moderate-temperature magmatic-hydrothermal gold deposit. Future deep-seated and surrounding gold exploration should center on this area. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calculate carbon emissions of energy consumption by using annual emission factors of indirect energy. • Put forward quantitative indicators of mine intelligence. • Impact of intelligence on carbon emissions of energy consumption in mining industry. • Prediction of carbon emissions in mining industry based on intelligent scenario analysis. The intelligent construction of the mining industry has become an emerging trend in its future development plans. As a traditional high energy consumption industry, its energy conservation and emissions reduction have become particularly urgent concerns. Therefore, it is of great significance to study the impact of intelligence on the carbon emissions from energy consumption in the mining industry. This paper first uses dynamic indirect energy emissions factors to build an accounting model for carbon emissions from energy consumption in the mining industry and calculates the related carbon emissions from 2001 to 2020 by sector. Then, an expandable stochastic environmental impact assessment (STIRPAT) model is established to analyze the impact of intellectualization on the carbon emissions intensity of China's mining industry. At the same time, many other important factors are included in the model, and the model is fitted using ridge regression. The results show that the order of influence, from large to small, is as follows: energy intensity, industrial output value, per capita output value, the proportion of output value of large and medium-sized enterprises, per capita stock of fixed assets, average enterprise output value, R&D intensity and proportion of indirect energy. Each 1% increase in the above factors will increase the corresponding carbon emissions intensity by 0.2005%, −0.1271%, −0.1207%, 0.7467%, −0.0595%, −0.09813%, 0.1143% and −0.1419%, respectively. Then, the prediction values of the independent variables are obtained by using the scenario analysis method and grey prediction model, and 12 scenarios are set up to predict the carbon emissions intensity of the mining industry energy consumption from 2021 to 2035 by using the expanded STIRPAT model. By analyzing the prediction results, we conclude that Scenario 8, Scenario 9, Scenario 10, Scenario 11 and Scenario 12 can achieve the emissions reduction goals of the mining industry in 2025 and 2030; the optimal path of emissions reduction is given for various scenarios. Finally, a development strategy for emissions reduction in China's mining industry is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • In the case of a small number of known deposits and mineral occurrences, the prospecting prediction model based on the Siamese network can extract effective features without relying on prior knowledge to realize supervised prospecting prediction. • On the basis of sliding window data enhancement, this paper generates paired sample data sets by randomly combining deposit samples and non-deposit samples, which can further enhance the data and improve the generalization ability and prediction accuracy of the model to a certain extent. • Compared with the prediction results of the weight of evidence method and the convolutional neural network, the prediction results of the Siamese network are better, and 7 new gold prospecting areas have been discovered in Zhangjiakou, Hebei Province, China. Supervised neural networks constitute an important research area for the intelligent prediction of locations for prospecting mineral deposits. Accurate training of a supervised neural network requires many training samples, something that is often difficult to obtain. This paper reports the use of geological, geochemical, and geophysical data by a Siamese network to overcome the problem of insufficient training samples, and implements a supervised deep learning prospecting prediction method based on the Siamese network. Intelligent prediction for gold deposits prospecting is carried out for the Chongli mineral concentrate area in Zhangjiakou, Hebei Province, China, and compared with the weight of evidence method and convolutional neural network model. The results show that:(a) the performance of the Siamese network model is no less than that of the convolutional neural network (CNN) model and better than that of the weight of evidence (WOE) method; (b) the gold prospective areas differentiated by the established models are strongly consistent with geological and metallogenic characteristics in the study area. This study suggests Siamese network model as an effective mineral prospectivity modeling tool. This method is also suitable for prospecting prediction using geoscience data in other areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four types of HREE-rich minerals are identified in the giant Bayan Obo deposit. • The identified HREE-minerals were mainly precipitated from carbonatite-relate fluids. • A local physiochemical environment that facilitated the formation of niobium oxides is significant for efficient HREE deposition. The carbonatite-related Bayan Obo deposit, China is the largest REE resource in the world. This deposit has long been a major light REE (LREE) producer, with heavy REE (HREE) rarely exploited. In order to better understand the occurrence of HREE in the deposit, this paper conducts a study of HREE-rich minerals at Bayan Obo. Overall, four types of HREE-rich minerals are identified, including fergusonite-group mineral [(Y, REE)(Nb, Ta, Ti)O 4 ], samarskite-group mineral [(Y, REE, Fe) 2 (Nb, Ta, Ti) 2 O 8 ], aeschynite-group mineral [(Y, REE, Ca, Th, U)(Nb, Ta, Ti) 2 O 6 ], and a type of unknown Pb-rich mineral. These minerals have HREE contents varying from 3.4 wt% to 46.4 wt%, mostly between 19.7 wt% and 34.3 wt%. Yttrium, Dy and Gd are the major REE constitute. Textual relations indicate that the HREE-rich minerals were mainly precipitated from carbonatite-related fluids, with small amounts of grains crystallized from the carbonatitic magma or deposited from post-ore modification fluids. The HREE-rich minerals occur in close temporal and/or spatial association with LREE minerals (e.g., monazite and bastnäsite), so formation of these HREE-minerals does not mean strong LREE-HREE fractionation during the ore-formation or post-ore modification process. Given that certain niobium oxides strongly prefer HREE relative to LREE in the mineral structure, a local physiochemical environment that allowed for the deposition of niobium oxides may be significant for efficient HREE deposition. Although HREE-rich minerals are not widely present in the deposit, they tend to occur as clusters in places. To determine what proportions of HREE can be hosted in the HREE-rich minerals, the weight proportions and REE contents of major REE-bearing minerals were measured in three representative ore samples. The results show that ∼ 25–57 % HREE can be hosted in fergusonite, samarskite, and/or aeschynite. Therefore, the newly identified HREE-rich minerals are non-negligible targets for future exploitation of HREE in the Bayan Obo deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The metallogenic mechanism of ion-adsorption REE deposits is reviewed. • The mineral evolution of clay minerals during deposit formation is discussed. • The REE adsorption mechanism by clay minerals is summarised. • The controlling factors of REE leaching from clay minerals are determined. Ion-adsorption rare earth elements (iREE) deposits are the globally predominant source of heavy rare earth elements (HREE), which are mainly discovered and mined in southern China. This paper reviews the genesis and mining mechanisms of iREE deposits. These deposits are mainly formed in the weathering crust of rare earth elements (REE)-rich granites, volcanic rocks and metamorphic rocks. During the weathering and eluviation, REE are released by the dissolution of REE-bearing minerals, depending on the weathering resistance of such minerals. Then, aqueous REE cations migrate downwards and are adsorbed by clay minerals. The adsorption and fractionation of REE are affected by variations in oxygen, pH and ionic species and strength. REE are mainly adsorbed on clay minerals through ion exchange and surface complexation. The former reaction cannot cause evident REE fractionation, whereas the latter induces an enrichment of HREE over LREE. The enrichment and fractionation characteristics of REE are also constrained by their occurrence states. REE with different occurrence states can be distinguished via sequential extraction, and the micro-occurrence states of REE can be probed using high-sensitivity, high-resolution characterisation. Furthermore, the leaching mechanism of iREE deposits is summarized, where REE are exchanged by foreign cations. Ammonium sulphate is the main leaching agent, but its excessive use can cause serious environmental pollution. Thus, leaching agents with little or no ammonium, such as MgSO 4 and CaCl 2 , have been recommended. The controlling factors of REE leaching are the concentration of leaching agents, pH, temperature and solid/liquid ratio. The above summary deepens the understanding of the formation mechanism of iREE deposits and provides beneficial information for the efficient but green mining of iREE deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • We developed an ensemble mineral prospectivity mapping method based on attention-based convolutional neural network. • The proposed ensemble method improves mineral prospectivity modeling accuracy by learning the key channel feature attentively. • Mineral potential map of W–Sn deposits in Nanling metallogenic belt was produced using the proposed method. Data-driven mineral prospectivity mapping (MPM) based on deep learning methods has become a powerful tool for mineral exploration targeting in the past years. Convolutional neural networks (CNNs) have shown great success in this field because of their powerful ability to capture the complex spatial geo-anomalies related to mineralization. However, the exploration big data applied to MPM mainly relies on the high dimensions of evidence layers (other than spatial dimensions), namely, a large number of channels. This impedes the extraction of key channel features related to mineralization when using traditional CNNs. In this paper, we developed an ensemble MPM method based on CNN and Attention model: the ATT–CNN method. Specifically, a channel attention layer is added after the convolution operation of the CNN to enhance the extraction of key channel features in complex exploration data, thereby improving the feature extraction ability and prediction accuracy of CNN for MPM. A case study of W–Sn mineral prospectivity modeling in the Nanling metallogenic belt in South China was used to verify the proposed method. To alleviate the issue of training sample scarcity, we used data augmentation methods (including sliding window and random zero noise addition) when training CNN models. The results show that the prediction accuracies of the ATT–CNN model (92.949% and 94.872% using sliding window and random zero noise addition, respectively) are higher than those of the traditional CNN (91.667% and 92.308%, respectively). Moreover, the improved areas under the receiver operating characteristic curves (AUC) of ATT–CNN (0.987 and 0.971) compared to those of the CNN (0.970 and 0.964) suggest that the proposed ensemble method improves the geological generalization of CNN. The high agreement with known deposits suggests that the areas targeted in this study can guide future mineral exploration of the W–Sn mineralization in the Nanling range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluid overpressure as well as rapid decompression plays an important role in mineralization and deformation. • Rock deformation reveals the main factor controlling the mineralization and fluid circulation. • There has positive feedback between the fluid overpressure, strain localization and mineralization. Understanding the coupled process of deformed microstructure and fluid evolution of ore veins therefore provides insight into processes that influence mineralization distribution and its mechanism. Gold is often developed in quartz veins in many gold deposits. This paper presents detailed evidence for solid deformation, hydrothermal fluid, and mineralization in a fault-controlled gold-silver-bearing quartz vein from the Yushishan gold deposit, Altyn Mountain, NW China. Macro-and microstructure combined quartz crystal preferred orientation (CPO) unravel the ductile–brittle transition deformation of quartz veins formed at the deep crustal level ca. 9 ∼ 13 km and the deformation temperature ranging between 180 ∼ 381 °C. The homogenization temperatures and salinities of fluid inclusions change slightly, while the trapping pressure of fluid inclusions has a large fluctuation of ca. 125 ∼ 275Mpa. H O isotopes and the composition of fluid inclusions decipher the source of ore-forming fluid mainly related to the regional magmatic-metamorphic event. Combined with the fluid immiscibility that is evidenced by different types of fluid inclusion coexistence characteristics and the pH increase induced by CO 2 degassing in an inhomogeneous fluid system, it is suggested that an obvious fluid overpressure and rapid decompression occur during Au deposition from the quartz vein. The seismically fractured opening and healing of rocks during ductile–brittle deformation controls the formation of the mineralization and fluid circulation. There has positive feedback between the fluid overpressure evolution, strain localization and mineralization through time. The channelized and circulated fluid flow triggered extensive veining, mineral growth, and connections with fluid reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The genetic stage of siderite nodules of Late Paleozoic coal measures in North China epicontinental Sea Basin was identified. • The material source of siderite nodules in the study area was identified. • The genetic mechanism of siderite nodules in the study area was clarified. • The genetic model of siderite nodules in epicontinental sea basin coal measures was established. Siderite is a mineral resource and a climate sensitive mineral. Siderite nodule layers are widely developed in coal measures within the marine-ontinental transitional facies of North China epicontinental sea basin, yet their formation environment and genetic mechanism are poorly understood. In this paper, taking the siderite nodule layers in the coal measures of the Late Paleozoic Taiyuan Formation in Zibo area of North China as an example, the formation environment and genetic mechanism of siderite nodules in the transitional facies of the epicontinental sea basin are studied through detailed petrological, sedimentological and geochemical analysis. It is found that the siderite nodules in the research area were formed in a tidal flat-lagoon environment. The siderite nodules are formed in the synsedimentary stage, the original information of chemical composition and characteristics of the nodules being largely retained. Most of the carbon in the siderite nodules originates from inorganic carbon from marine carbonate rocks, with the remainder originating from inorganic carbon formed by dissimilatory iron reducing bacteria (DIR) degrading organic matter. Meanwhile, most of the iron in the siderite nodules originates from hydrothermal fluids, and the remainder from terrigenous sediments. The content of iron input from hydrothermal fluids and terrestrial sediment represents a trade-off relationship. The two genetic mechanisms of the siderite nodules are as follows: 1) Chemical genetic mechanism: The siderite nodules are mainly formed by the combination of low-valence iron (Fe2+) and inorganic carbon in seawater through reduction with iron input from hydrothermal fluids as the main source. 2) Biochemical genetic mechanism: Some is formed by the combination of low-valence iron (Fe2+) and inorganic carbon with high-valence iron (Fe3+) as an oxidant to degrade the organic matter and convert organic carbon into inorganic carbon through DIR. On this basis, a genetic model of the Late Paleozoic coal measures siderite nodules in the epicontinental sea basin is established. [ABSTRACT FROM AUTHOR]

[Display omitted] • Qingchengzi and adjacent areas at Liaodong have a high exploration potential for concealed gold mineralization. • Gravity and magnetic signatures used to locate faults, basement and Mesozoic intrusions. • Concealed contacts between granites and Precambrian metamorphic rocks are identified. • Gold deposits are controlled by structural intersections and lithological contacts. The eastern block of the North China Craton (NCC) has been completely decratonized and it hosts numerous early Cretaceous gold deposits dated at about 130–120 Ma. The Jiaodong Peninsula in the easternmost NCC is the largest gold producing district in China, and it hosts more than 150 gold deposits with known gold resources of over 5000 tonnes (t). Also located at the eastern margin of NCC, the Liaodong Peninsula is poorly explored at depths greater than 800 m, with no large concealed gold deposit being discovered yet. In this paper, we carefully analyzed the gravity and magnetic characteristics of the ore-controlling structures in both provinces, including faults, Precambrian basement metamorphic rocks and the Mesozoic granitic intrusions. The deep regional faults are characterized by linear gravity gradient zones or elongated positive magnetic anomalies. The Precambrian basement metamorphic rocks usually have large-amplitude gravity and magnetic highs, while the lithological contacts of Mesozoic granite intrusions are commonly defined by gravity lows or narrow magnetic high anomalies. Interpretations from gravity and magnetic signatures predict two concealed lithological contacts between Mesozoic granites and Precambrian metamorphic rocks beneath Liaodong and Jiaodong. The spatial locations of known gold deposits are then correlated with the concealed structures inferred from the gravity and magnetic data in our paper. Their spatial relationship suggests that the gold mineralization is mainly controlled by oblique regional faults along the structural and lithological contacts between Mesozoic granites and Precambrian metamorphic rocks. Additionally, the structural intersections of different ore-controlling faults, especially the hydrothermal alteration zones at the contacts between Precambrian basement metamorphic rocks and the Mesozoic granites, are most favorable for the gold mineralization in the Liaodong and Jiaodong areas. Many large gold deposits are documented along a deep-seated, but concealed, structure beneath the Jiaodong gold district, while the Qingchengzi ore field and its vicinity in the Liaodong Peninsula still remain underexplored, despite of having a very similar structural setting, and deserve further investigation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Songshan tin deposit occurred at the end of Late Cretaceous, not in Triassic as previous suggested. • The end of Late Cretaceous is another important tin metallogenic period in the Lancangjiang tin belt. • The tin mineralization not only can occur in the magmatic arc, but also in the hinterland behind the magmatic arc. The Songshan tin deposit is located in the northern Lincang granitic batholith along the Lancangjiang tin belt, Western Yunnan, southwestern China. The ore bodies mainly occur as tourmaline-quartz veins with NNE- and/or NW-trending in the Triassic Pinghejie granitic pluton, and the schist of the Proterozoic Songshan Formation. The previous study suggested the tin mineralization in the Songshan deposit should occur in the Triassic, but no directed age data support it. This hinders the understanding of the genesis of the Songshan tin deposit, especially the tin mineralization in the Lancangjiang tin belt. Here, we report the zircons U-Pb ages of 222.7 ± 1.6 and 222.0 ± 2.4 Ma for the granodiorite, 215.1 ± 1.5 and 223.0 ± 2.0 Ma for the biotite monzogranite, and 222.3 ± 2.3 Ma for the alter granite from the Pinghejie granitic pluton. The monazite from the monzogranite yields a U-Pb age of 212.8 ± 1.9 Ma. We also obtain two garnet U-Pb ages of 215.1 ± 8.7 Ma and 213.5 ± 7.2 Ma from skarn, and two cassiterite U-Pb ages of 76.6 ± 1.5 Ma and 79.6 ± 3.6 Ma from tin ores. These data suggest that tin mineralization in the Songshan deposit occurred at the end of Late Cretaceous, which is quite different from the ages of the Pinghejie granitic pluton emplaced and the formation of skarn. The zircon Hf isotopes (εHf(t) = –22 ∼ -12) and monazite Nd isotopes (εNd(t) = -13.04 ∼ -11.80) indicate that the Pinghejie granitic pluton was derived from the remelting of Paleoproterozoic crust. The paper concluded that the tin mineralization in the Songshan deposit occurred at the end of Late Cretaceous. It is another important metallogenic period in the Lancangjiang tin belt, which may be related to the subduction of the NeoTethys oceanic crust. The tin mineralization can not only occur in the magmatic arc, but also in the hinterland behind the magmatic arc. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Woxi deposit is an orogenic Au-Sb-W deposit. • U-Pb dating on apatite and wolframite yielded a robust gold mineralization age of ca. 141 Ma. • Pyrite in situ S-Pb isotopic signatures suggest the ore-forming metals and fluids mainly derived from a metasomatized lithospheric mantle. • This study provides a new example of orogenic gold deposit that was controlled by translithospheric processes in a back-arc environment far from the plate subduction zone. The majority of gold mineralization in the Jiangnan Orogenic Belt (JOB) of South China share similarities with the orogenic type, but the nature of mineralization remains controversial, especially in terms of intracrustal versus subcrustal origin of ore fluids and metals and their relationships with the subduction of the Paleo-Pacific plate. This paper reports results of in situ analyses of minerals closely related to gold mineralization, including U-Pb ages of apatite and wolframite, and S-Pb isotopes of pyrite, from the Woxi Au-Sb-W deposit in the western Jiangnan Orogen, and use them to address the above problems. The Woxi deposit, which consists of several auriferous quartz lodes hosted by ductile–brittle shear zones in the Neoproterozoic slate. The hydrothermal mineralization and alteration processes are divided into four stages. Early-ore stage (S1) is characterized by disseminated, euhedral, porous, coarse auriferous pyrite (Py1) with minor amounts of arsenopyrite, siderite, and rutile in the bleached slate. Main-ore stage (S2) is characterized by subhedral to euhedral, auriferous pyrite (Py2) with compositional zoning, with small amounts of wolframite and apatite in quartz veinlets. Late-ore stage (S3) is represented by scheelite and stibnite with minor amounts of native gold and anhedral, dendritic auriferous pyrite (Py3) in quartz veinlets. Post-ore stage (S4) features a quartz-calcite-barite-chlorite mineral assemblage that occurs as veinlets or in pressure shadows of Py1. Apatite and wolframite associated with Py2 yield a consistent U-Pb age of ca. 141 Ma, which is corresponded to a time when the Paleo-Pacific plate started to roll back, and a Basin-and-Range style tectonic regime began to developing in South China. The different stages of pyrite have variable S isotopes, with the δ34S CDT values (mainly between −6‰ and +1 ‰) largely overlapping with those of the metasomatized mantle (−5‰ ∼ + 5 ‰), and Pb isotope ratios between crustal and mantle values. Taking these results together, we proposed that the Woxi deposit and many other gold deposits in the JOB formed from subcrustal processes involving the metasomatized upper mantle above the subduction zone. Given the extended distance from JOB to the Paleo-Pacific plate boundary, the metasomatized mantle underneath the JOB is likely initially formed during the plate subduction leading to the formation of the JOB during the Neoproterozoic, which is further fertilized by upwelling asthenosphere due to rollback of the Paleo-Pacific plate in the Mesozoic. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trace elements in sphalerite and pyrite distributed in the form of solid solutions or micro-inclusions. • The mineralization in the Beishan Pb-Zn ore district was under a low-temperature condition. • The Pb-Zn deposits in the Beishan Pb-Zn ore district are MVT deposits. The Beishan Pb-Zn ore district, located in northern Guangxi, China, is a giant carbonate-hosted Pb-Zn ore district. In-situ trace element analysis was performed using LA-ICP-MS on sphalerite and pyrite from three representative Pb-Zn deposits in the Beishan Pb-Zn ore district. The analysis of these trace elements reveals the trace element compositions of the sulfides, the distributions and the substitution mechanisms of trace elements, physicochemical characteristics of the ore-forming fluids, and ore genesis. Sphalerite is enriched in Mn, Fe, Ge, and Cd, while it is poor in Co, Ni, Ga, As, In. Pyrite is enriched in Co, Ni, As, Tl, Sb, and Pb, but poor in Mn, Ga, Ge, Cd, In, Sn. Mn, Fe, Cd, Ga, Ge, Sb, Ag, and As in sphalerite enter the mineral lattice mainly by simple or coupled substitution mechanisms, while Cu and Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Mn, Co, Ni, As, Tl, and Sb in pyrite substituted Fe2+ by simple or coupled mechanisms, while Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Studies of trace elements related to temperature (e.g., Mn, Fe, Ga, Ge, In) in sphalerite and pyrite indicated that mineralization in the Beishan Pb-Zn ore district occurred under a low-temperature condition. And according to the sphalerite GGIMFis geothermometer, the mineralization temperature of the Beishan Pb-Zn ore district was 55–268 °C (average 153 °C), of which 110–230 °C(average 153 °C) in Duchuan, 92–268 °C (average 149 °C) in Beishan, and 55–243 °C (average 167 °C) in Dongyong. The Mn, Fe, Ga, Ge, and In contents of sphalerite are similar to those of MVT deposits. The combination of some binary pattern diagrams, principal component analysis (PCA), and Co/Ni ratios of pyrite, with the geological features and physicochemical properties of the ore-forming fluids, indicates that the Beishan Pb-Zn ore district is an MVT district. This paper, combined with previous studies, shows that the Co/Ni ratio of pyrite has some guiding significance for mineral exploration of this kind of Pb-Zn deposit, with Co/Ni values around 0.1 indicating that the deposit has a better prospect of developing into a large deposit, and Co/Ni much less than 0.1 indicating that the deposit may not have a good prospect. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Bozhushan batholith consists of metaluminous and peraluminous granites. • The two phases of granites share a common crustal source. • The peraluminous granites were derived by differentiation of metaluminous melts. • Tin enrichment was significantly controlled by the magmatic differentiation. Most primary tin deposits are closely temporally and spatially related to peraluminous granites. These granites usually exhibit highly evolved geochemical characteristics that disguise their specific origin. This paper reports a study of whole-rock geochemistry and Sm–Nd isotopes, zircon U–Pb geochronology and Lu–Hf isotopes, and mineral chemistry of the Bozhushan granitic batholith in the Youjiang basin, South China. The Bozhushan batholith, producing the Bainiuchang large tin–polymetallic deposit, consists of metaluminous tin-barren monzogranites and peraluminous tin-bearing monzogranites. LA-ICP-MS zircon U-Pb dating suggests that the peraluminous rocks were emplaced during the Late Cretaceous (88.5 ± 0.7 Ma), which is largely consistent with the emplacement age of the metaluminous rocks. These granitic rocks have similar Nd-Hf isotopic compositions, supporting a common crustal source. Relative to the metaluminous monzogranites, the peraluminous tin-bearing rocks exhibit more evolved geochemical compositions with higher Si and lower Ca, P, Mg, Fe, and Ti and stronger depletion in Eu, Ba, Sr, Zr, Hf, and rare earth elements. These differing geochemical characteristics can be explained by the differentiation of biotite, plagioclase, zircon and apatite. The extremely low Nb/Ta (<5) and K/Rb (<150) ratios of the peraluminous rocks indicate a fluid exsolution process. We suggest that the peraluminous tin-bearing rocks were derived by magmatic differentiation and fluid exsolution of the metaluminous melts. Combining our new results with previous studies, we conclude that on a worldwide scale some peraluminous granites related to tin mineralization are derived by magmatic differentiation and fluid exsolution of metaluminous melts rather than from metasedimentary rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mineralogy in the Caojiaba is similar to reduced tungsten skarns worldwide. • Wolframite grains yielded 206Pb/238U ages of 212.4 ± 1.0 Ma and 211.8 ± 1.1 Ma. • Reduced tungsten mineralization occurred during the late Triassic in the XZMP. The Caojiaba tungsten deposit (19.03 Mt@ 0.37 wt% WO 3) is hosted in skarn within clastic and carbonate rocks in the Xiangzhong metallogenic province (XZMP), southern China. The deposit is characterized by an early prograde skarn overprinted by a retrograde assemblage, and then by quartz–scheelite–sulfide veins. The Caojiaba skarn is characterized by grossular garnet (Grs 65–85 Adr 7.1–31) and hedenbergitic pyroxene (Hd 63–86 Di 11–33), similar to the well–studied reduced tungsten skarns worldwide. In this paper, we present in-situ laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) analysis of U–Pb isotopes and trace elements of wolframite grains coexisting with scheelite in the quartz–scheelite–sulfide veins. Uranium is correlated positively with Nb5+, tetravalent (Ti4+, Sn4+, Zr4+, Hf4+), and trivalent (Sc3+, V3+, Y3+, REE3+) cations in all wolframite samples, suggesting that the incorporation of U into wolframite is controlled by the coupled substitution mechanisms. Two wolframite samples (CJB–43 and CJB–44) yielded 206Pb/238U ages of 212.4 ± 1.0 Ma (2σ, n = 50, MSWD = 0.92) and 211.8 ± 1.1 Ma (2σ, n = 43, MSWD = 1.4), overlapping with the late Triassic granitic rocks (225.6–204.5 Ma) in the XZMP. Mineralogical and geochronological evidence collectively indicate that Caojiaba is a typical example of the late Triassic reduced tungsten skarn deposits in the XZMP. This study demonstrates the potential of U–Pb dating of wolframite and highlights its importance for directly dating hydrothermal ore–forming processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ore-forming element associations were established by PCA. • Anomaly components were extracted by SVD. • Ore-propecting targets were identified based on the anomaly components. Multi-stage geological processes (i.e. magma and hydrothermal processes) produce generally regional and local element concentration anomalies of ore-forming elements. The Principal Component Analysis (PCA) can be applied to establish various types of ore-forming element associations, which can be further divided into two different anomalous components with the help of the Singular Value Decomposition (SVD). One can be defined as a regional geochemical anomaly generated by geological processes (i.e. magmatism); and the other can be regarded as a local geochemical anomaly created by ore forming events. Three aspects are illustrated in this paper: (a) The ore-forming element associations are established by PCA; (b) The geochemical anomaly components created by both magmatism and hydrothermal ore-forming processes are respectively identified by the SVD from the ore-forming element associations; and (c) The regional and the local geochemical anomalies are delineated using the geochemical anomaly components corresponding to different eigenspaces. The PCA and SVD methods were applied gold polymetallic ore-prospecting target areas and molybdenum polymetallic ore-prospecting target areas in the Jiaodong gold cluster area, China by delineating their regional and local geochemical anomalies. The results show that the SVD can extract not only the regional anomalies associated with magmatism, but also the local anomalies related to the hydrothermal processes from multi-element associations produced by PCA. [ABSTRACT FROM AUTHOR]

• Two mineralization stages are recognized in Yaojialing zinc skarn deposit. Cobalt and tellurium minerals deposited in the early sulfide stage, selenium minerals deposited in the late sulfide stage. • The distribution of critical minerals resources in Yaojialing deposit varies spatially and temporally. Late stage sphalerite is more enrich Cd but exceptionally low in Co and Se than in the early stage. • Early stage pyrite is more enriched Co and Se, Se is also enriched in chalcopyrite, Te only occurs in tellurium minerals. • Temperature is the main factor affecting the distribution of these critical minerals resources. Critical minerals resources are widely used in emerging industries, and their mineralization characteristics and metallogenic regularity are of high importance. Skarn deposits are one of the important sources of critical minerals resources. Yaojialing deposit is a typical large skarn zinc polymetallic deposit in Tongling district of the Middle and Lower Yangtze River metallogenic belt. The ore bodies are mainly lenticular and veined occurrence along the proximal skarn zone and structural or lithologic contacts, respectively. We recognize five hydrothermal stages in the deposit: skarn stage, oxide stage, early sulfide stage, late sulfide stage and carbonate stage. The early and late sulfide stages are the main ore-forming stages. In addition to the production of zinc, gold and copper, the deposit also contains critical element resources such as cadmium, cobalt, selenium, and tellurium. Taking the Yaojialing deposit as an example, this paper shows the occurrence and distribution of critical minerals resources in a typical skarn deposit by using scanning electron microscope, TESCAN integrated mineral analyzer (TIMA), and sulfide LA-ICP MS analysis. Although there are no cadmium minerals in Yaojialing deposit, cadmium can incorporated in the sphalerite lattice, and sphalerite in veins has elevated cadmium content (average 5478.78 ppm). Tellurium content in various sulfides is very low, and it does not enter into the sulfide lattice. It mainly forms tellurobismuthite, hessite and tetradymite, which occur in Cu-Zn ore formed in the early sulfide stage, there are 227 tetradymite grains in a single rock section. Selenium occurs as naumannite in vein ore in the distal of the deposit; selenium can also incorporated the lattice of chalcopyrite and sphalerite, and the selenium content is elevated in sphalerite formed in the early sulfide stage (average 226.80 ppm). The cobalt mineral glaucodot is only found in skarn ore; cobalt easily incorporated the lattice of pyrite and sphalerite, and pyrite and sphalerite formed in the early sulfide stage are enriched in cobalt (average 1962.18 ppm). The characteristics of trace elements in pyrite and sphalerite show that temperature is the main factor affecting the distribution of critical minerals resources, high temperature is conducive to the enrichment of cobalt, selenium and tellurium, while low temperature is conducive to the enrichment of cadmium. Cadmium, cobalt, selenium, and tellurium have high content in specific parts of the deposit, which makes them potentially amenable to recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magmatic and hydrothermally altered titanite were identified in Luming deposit • U-Pb dating and Nd isotope of titanite be used to constrain the source andnature of ore-forming fluids. • Titanite has potential to act as an pathfinder mineral for the formation of porphyry Mo deposits. Northeastern (NE) China is one of the most important regions for Mo resources in China with more than 80 porphyry/skarn Mo deposits, most of which were formed in the Mesozoic. Geology, geochemistry and geochronology of individual deposits have been studied and a large amount of data was accumulated, but the factors controlling large-scale Mo mineralization in this region is still debated. To better understand the factors controlling the Mo mineralization, three typical large to giant Mesozoic porphyry Mo deposits located in NE China, namely the Daheishan (DHS), Fu'anpu (FA) and Luming (LM) deposits have been selected. In this paper, U-Pb age, elemental and Nd isotopic compositions of titanite from these deposits have been analyzed to reveal their chemical and isotopic compositions, which provide insights into the nature of source magmas and unravel the physical and chemical conditions of Mo mineralization. In-situ titanite Nd isotopic compositions from all the ore-related granites indicate that they originate from a juvenile crustal source. Titanite occurring as euhedral grains in DHS, FA and LM ore-related granites are characterized by high Th/U and LREE/HREE ratios, as well as low Lu/Hf and 147Sm/144Nd ratios, indicate a magmatic origin. In the LM-barren granite, titanite occurs as magmatic and hydrothermally altered type. The euhedral envelope-shaped magmatic titanite has the same characteristics as the titanite in DHS, FA and LM ore-related granites, with higher Th/U and LREE/HREE ratios and lower147Sm/144Nd ratios. In contrast, hydrothermally altered titanite in the LM-barren granite has lower Th/U and LREE/HREE ratios, as well as higher Lu/Hf and 147Sm/144Nd ratios, distinct Eu anomaly and tetrad effect than the magmatic titanite. In-situ magmatic titanite U-Pb dating of DHS, FA, LM ore-related granite yields crystallization ages of ca.168 Ma, ca.166 Ma and ca.178 Ma, respectively, which are consistent with the mineralization ages within error. Hydrothermally altered titanite in the LM-barren granite yields a crystallization age of 177.9 ± 2.3 Ma (MSWD = 2.3), which is indistinguishable from the LM-ore granites and molybdenite Re-Os age, implying that the formation of the Luming porphyry Mo deposit was coeval with the wall-rock alteration. Relatively homogeneous and consistent Nd isotopic compositions of magmatic titanite from LM-ore granite and hydrothermally altered titanite from LM-barren granite suggest that the hydrothermal fluids have the same origin with the granite and could be directly exsolved from the ore-forming magma. Trace element characteristics of magmatic titanite from these porphyry Mo deposits show that the magma of ore-related granite has higher oxygen fugacity and water contents than those of the LM-barren granite. Hydrothermally altered titanite in the LM-barren granite shows higher F contents than that in the magmatic titanite. The results from this study show that high Mo content in the source region is a prerequisite for the formation of porphyry Mo deposits but the specific magma composition (e.g., with abnormally high Mo contents) may be not critical. Other factors such as the higher F, oxygen fugacity and water contents are also important for Mo mineralization, which could lead to the magma evolution and accumulation of metal elements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four paragenetic stages are recognized at the Devonian Huodehong sulfide deposit. • The sedimentary pyrite might act as a geochemical barrier for locating hydrothermal Pb-Zn mineralization. • The wide variation of δ34S values of sulfides is ascribed to multiple sulfur sources. The Devonian sedimentary rocks in South China host numerous sulfide deposits (e.g. the Siding and Beishan Pb-Zn sulfide deposits, and the Yingde iron sulfide deposits) that are distinctly characterized by a wide variation of δ34S values in sulfides (−28.7‰ to +42.8‰). Such signature, however, has not been investigated in depth and thus the metallogeny of these deposits remain poorly understood. This paper investigated the Huodehong deposit hosted by sedimentary rocks of the Middle Devonian in the western Yangtze Block, South China. A complex paragenesis has been defined: I) micro-grained pyrite (Py1) associated with organic materials; II) radial and crustiform pyrite (Py2) and marcasite (Mc1) aggregates; III) subhedral-anhedral pyrite (Py3), microcrystal colloform sphalerite (Sp1), and dendritic galena; and IV) coarse-grained euhedral sphalerite (Sp2) occurred as veinlets. The mineralogical evidence shows that the Py1 occurred as syn -sedimentary pyritic stromatolites, which is overprinted by cavity-filling hydrothermal Py2, Py3, Sp1, and Sp2. In situ S isotopes show that the δ34S values of Py1-Py3 and Sp1 range from –22.8‰ to −10.8‰. Such highly depleted heavy sulfur isotopes indicate that the reduced sulfur was mainly derived from bacterially reduced seawater sulfate in an open system. The Sp1 has similar δ34S values to its reworking Py1, implying that part of reduced sulfur was sourced from sedimentary pyrite. Such sedimentary pyrite might act as a geochemical barrier in accelerating sulfate reduction via the hydrolysis of Fe2+ resulting an increase in the H+ concentration and the formation of HSO 4 −. In addition, the Sp2 has slightly depleted heavy sulfur isotopes (δ34S = −9.3‰ to −1.1‰), implying the late input of heavy sulfur isotopes component. Hence, the highly heterogeneous sulfur isotopes at Huodehong likely resulted from bacterial sulfate reduction coupled with reworking sedimentary pyrite, and subordinate incorporation of 34S-rich sulfur. The reduced sulfur of the Huodehong deposit has multiple sources (i.e. sedimentary pyrite and sulfate-bearing evaporites), and the ore formation has experienced the epigenetic hydrothermal mineralization with mixture of metals from the metamorphic basement rocks. The outcomes will have a great implication for understanding the origin and exploration of the Devonian sulfide deposits in South China. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ages of W ores by wolframite U-Pb dating in Jinzhuping, Changkeng, Keshuling, Taoxikeng and Bikeng deposits, southern Jiangxi, are 154.2 ± 4.1 Ma, 157.8 ± 9.4 Ma, 150.3 ± 1.8 Ma, 153.8 ± 4.0 Ma and 152.3 ± 5.6 Ma, respectively. • Three stages of W mineralization occurred from the Triassic to the Lower Cretaceous in the Nanling Range of South China. In situ LA-ICP-MS provide high-resolution spatial analysis of wolframite grains. In this paper, wolframite U-Pb isotope dating is presented to directly constrain the timing of W mineralization in five granite-related vein-type W-polymetallic deposits from different ore-concentrated areas in southern Jiangxi Province, South China. In the Jinzhuping, Changkeng, Keshuling, Taoxikeng, and Bikeng deposits, wolframite is the dominant ore mineral, occurring as coarse, euhedral grains that are associated with gangue minerals such as cassiterite, scheelite, molybdenite, sphalerite, (±) galena, (±) marmatite, pyrite, quartz, (±) chlorite, (±) fluorite, and calcite. Wolframite U-Pb dating yielded 206Pb/238U ages of 154.2 ± 4.1 Ma for the Jinzhuping deposit, 157.8 ± 9.4 Ma for the Changkeng deposit, 150.3 ± 1.8 Ma for the Keshuling deposit, 153.8 ± 4.0 Ma for the Taoxikeng deposit, and 152.3 ± 5.6 Ma for the Bikeng deposit, respectively. By comparing the published minerlizing ages of the W-Sn polymetallic deposits in the Nanling region, we suggest that three stages of W mineralization occurred from the Triassic to the Lower Cretaceous. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wavelet-based neural network with Monto Carlo simulation is introduced for data-driven mineral prospectivity mapping. • The proposed algorithm alleviates the data imbalance issue and accesses the uncertainties in mineral prospectivity mapping. • We present a mineral prospectivity map of W-Sn ore deposits in the Nanling metallogenic province, China. The Nanling Range in South China is endowed with abundant W-Sn and other important rare metal resources associated with granitic intrusions, but the rate of new major mineral discoveries has been drastically diminished over the last decades. Data-driven mineral prospectivity mapping (MPM) using machine learning is emerging as a powerful tool in support of mineral exploration targeting at regional or camp scale. However, MPM based on supervised learning faces some general problems, notably including subtle information obscured in exploration data and imbalanced training samples. In this paper, we proposed a novel ensemble scheme for MPM using wavelet neural network (WNN) and Monte Carlo simulation (MCs) to address the forementioned issues. Specifically, the purpose of using WNN based on multiscale wavelet analysis is to capture weak or hidden (geophysical and geochemical) information caused by concealed ore deposits, while an undersampling MCs (UMCs) algorithm is employed to assess uncertainties caused by data imbalance and lessen its impact on MPM. Subtle (weak and mixing) information related to concealed mineralization, including geophysical and geochemical anomalies, were extracted using wavelet analysis at first, and then a dozen of predictive evidences was integrated based on WNN using UMCs for producing a W-Sn perspectivity map. The results suggest that WNN has a higher prediction accuracy (∼90%) in comparison to the artificial neural network (ANN) (∼85%). Moreover, the improved AUC value (∼0.9) of WNN based on UMCs compared to the classic ANN (∼0.82) and WNN (∼0.85) suggests that the proposed ensemble algorithm improves the geological generalization of machine learning. Revisiting WNN predictions by uncertainties produced more sharply focused exploration targets of W-Sn deposits (covering ∼5% of the study area). The resulting predictive map provides important clues of W-Sn deposit occurrences which could guide and stimulate future mineral exploration in the Nanling Range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three ML-based classifiers are established to discriminate ore origins. • The classifiers predict Qingchengzi is of magmatic–hydrothermal origin. • In situ S–Pb analyses confirm the prediction results. As geosciences enter the era of big data, machine learning (ML) that is successful in big data, is now contributing to solving problems in the geosciences, yet there have been few applications in economic geology. This paper highlights the effectiveness of ML-based methods coupled with mineral geochemistry in revealing the origin of the Qingchengzi Pb–Zn ore field in China, which are either metamorphosed sedimentary exhalative (SEDEX) or magmatic–hydrothermal fluid related deposits. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) pyrite trace elements coupled with decision tree (DT), K-nearest neighbors (KNN), and support vector machine (SVM) algorithms were applied to train the classification models. Testing of the DT, KNN, and SVM classifiers yielded accuracies of 98.2%, 96.4%, and 93.6%, respectively. The trained classifiers predict that the strata-bound and vein-type ore bodies at Qingchengzi ore field have a magmatic–hydrothermal origin, with DT, KNN, and SVM values of 100%, 97.4%, and 97.4%. In situ δ34S values of pyrite from strata-bound and vein-type ore bodies are 4.04‰ to 9.10‰ and 6.31‰ to 9.29‰, respectively, slightly higher than those of magmatic intrusions. In situ Pb isotopic ratios plot on the upper crust curve and yield two-stage model ages that are younger than metamorphic events in the region. Principal component (PC) analysis was used to determine the formation of the two types of mineralization. Pyrite from vein-type ore bodies (Py1) has lower contents of PC1 elements (Cu, Zn, Ge, Ag, Cd, Sn, Sb, and Pb) and higher contents of PC2 elements (Co, Ni, and Se) compared with pyrite from strata-bound ore bodies (Py2). Combined with previous fluid inclusion data, the vein-type ore bodies are inferred to have formed at higher temperatures than the strata-bound ore bodies. This study presents three visual classifiers to discriminate metamorphosed SEDEX and magmatic–hydrothermal Pb–Zn deposits. The prediction of classifiers and in situ S–Pb isotopic compositions suggest that the Qingchengzi Pb–Zn deposits have a magmatic–hydrothermal origin. The results demonstrate the effective application of ML-based methods to examine the origin of ore deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Apatite from both the Huashan and Wenyu plutons are fluorapatite of magmaticorigin. • Wenyu apatite formed under a higher oxidation state and incorporated more mantle-derived materials than Huashan apatite. • Wenyu apatite crystallized earlier than feldspar and Huashan apatite was affected byfeldsparcrystallization. • The magma of the Wenyu pluton incorporated more intensive fluid exsolution during crystallization. • Wenyu pluton is more favorable to gold mineralization than the Huashan pluton. The relationship between granitic magmatism and lode gold mineralization has remained as a controversial topic among economic geologists. In this paper, we report in situ elemental and Sr isotopic signature of apatite from the Wenyu and Huashan granitic plutons in the Xiaoqinling goldfield, southern margin of the North China Craton (NCC), intending to provide further constrain the relationship between magmatism and metallogeny. The formation ages of Huashan and Wenyu granitic plutons are coeval with the gold mineralization, but most of the gold deposits are clustered nearing the Wenyu pluton, and only a few small gold deposits are found adjacent to the Huashan pluton. Although apatite from both plutons is all fluorapatite, characterized by negative Eu anomaly and enrichment of LREEs, the apatite from the two plutons shows different signatures. Based on these differences, the apatite from the Huashan pluton is divided as group A (HS-A) and group B (HS-B). The δEu, δCe values and MnO and Ga contents of the Wenyu and HS-A apatite indicate high oxygen fugacity range from MH to NNO for the magma, whereas the HS-B apatite shows low oxygen fugacity range from NNO to FMQ. The 87Sr/86Sr, REE, Th/U, and Ce/Y values of the apatite suggest that the magma for the Wenyu pluton incorporated more mantle-derived materials in contrast to Huashan pluton. Sr/Y ratio and REE content of the apatite indicate that WY apatite crystallized earlier than feldspar and Huashan apatite was affected by feldspar crystallization. The fluid-volatiles exsolution texture and S content of the apatite indicate higher content of volatiles in the Wenyu pluton magma, where the magma experienced more intense fluid exsolution than that of the Huashan pluton during apatite crystallization. The characteristics of many mantle-derived materials, high oxygen fugacity, and higher volatiles as revealed by the apatite data show that the magmatism of Wenyu pluton was more conducive to the mineralization of gold deposits than that of the Huashan pluton and is more closely related to gold deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mineralized fluids are characterized by weakly acidic, reduced, and low temperature. • W/R interaction and CO 2 degassing caused the precipitation of carbonate minerals. • Mixing of metals and BSR-originated S2− resulted in the sulfide precipitation. • The origin of the Banbanjie deposit is similar to that of the MVT deposits. This paper investigates the origin of the newly discovered Devonian carbonate-hosted Banbianjie Ge-Zn deposit in South China. This deposit is rich in Ge (>900 t @ 110 ppm Ge) and contains 7.7 Mt of sulfide ores at a mean grade of 5.1 wt% Zn. The mineralization is stratabound or veined and is structurally controlled by the E-W trending Huangsi fault. Sulfide ores are dominated by sphalerite and dolomite with subsidiary pyrite, marcasite, and calcite, and minor galena. The mineralization forms massive, veined, brecciated, and disseminated structures and the hydrothermal minerals present in the deposit have colloform, fibrous, granular, and acicular textures. The hydrothermal dolomite has positive Ce (δCe = 1.13–1.20) and negative Eu (δEu = 0.43–0.68) anomalies that are indicative of formation in a weakly acidic, reduced, and low-temperature environment. The δ13C PDB and δ18O SMOW values of the dolomite range from −0.97‰ to −0.24‰ and +13.89‰ to +21.84‰, respectively, indicating that the dissolution of carbonate wall rocks was involved in the formation of hydrothermal dolomite. Theoretical C-O isotopic calculations further suggest that the hydrothermal dolomite formed as a result of water/rock (W/R) interaction and CO 2 degassing. The δ34S values of the sulfides (−11.23‰ to −4.95‰) are markedly lower than those of the Devonian seawater sulfate and sulfate from evaporates in the Devonian strata (+21.9‰ to +25.9‰), suggesting that the reduced sulfur was derived from evaporates within the ore-hosting sedimentary rocks by bacterial sulfate reduction (BSR). The Banbianjie sulfides have an upper crustal Pb isotopic affinity, as demonstrated by their 206Pb/204Pb (18.335–18.343), 207Pb/204Pb (15.725–15.735), and 208Pb/204Pb (38.288–38.326) ratios, suggesting the metals were derived from metamorphosed basement rocks. These data suggest that: i) the Banbianjie deposit formed as a result of a combination of weakly acidic, reduced, and epigenetic low temperature mineralized fluids, trap structures, and favorable lithologies; ii) W/R interaction and CO 2 degassing caused the precipitation of hydrothermal dolomite, whereas mixing of metals and S2− was the main formation mechanism of the sulfides; and iii) the Banbianjie Ge-Zn deposit is a typical Mississippi Valley-type (MVT) deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • Field-portable exploration methods were systematically described in shallow overburden areas for vein-type fluorite deposits. • The advantages and disadvantages of field-portable fluorite exploration methods have been analyzed. • The Effectiveness of RS + VLF-EM + PRXF for exploration has been validated by trenching and drilling. Fluorite deposits are widespread throughout eastern China and commonly occur in vein systems. These vein-type fluorite deposits are the primary source of fluorine worldwide and were predominantly formed during the Mesozoic or Cenozoic periods. In the absence of ore outcrops, fluorite exploration is necessarily concentrated within the shallow overburden area. The Wuliji'Oboo fluorite deposit is an example of a medium–low temperature vein-type subsurface orebody in eastern Inner Mongolia. Five portable technology methods have been implemented within the study area, including multispectral remote sensing (RS) technology, very low-frequency electromagnetic measurement (VLF-EM), portable X-ray fluorescence analyses (PXRF), portable gamma-ray spectroscopy, and partial extraction geochemistry. This paper describes the application principles, influencing factors, and technical solutions for each method. By investigating various examples, the applications of portable technology methods and their associated limitations were evaluated. Combining geological research with multi-spectral RS techniques is essential for optimum fluorite ore body prediction, thus narrowing prospecting targets. First, the target area was scanned using VLF-EM to identify the distribution of potential anomalies. Second, PXRF was used to distinguish the mineralised anomaly. Finally, trenching and drilling were performed to verify the effectiveness of the combination of methods. This study establishes a geology-geophysics-geochemistry-remote sensing integrated exploration model that may provide theoretical and technical support for the prediction of fluorite ore bodies in large Quaternary shallow overburden areas. [ABSTRACT FROM AUTHOR]

• Dictionary learning is used to model gold prospectivity for gold exploration targeting. • The case study shows that the dictionary learning model is no inferior to the logistic regression model and superior to the one-class SVM model. Machine learning and deep learning anomaly detectors have been successfully used to map mineral prospectivity. However, the establishment of machine learning or deep learning anomaly detection models for mineral prospectivity mapping often requires the determination of a set of initialization parameters in the absence of ground truth data. Improper initialization parameters will degrade the performance of these mineral prospectivity mapping models. Different from most machine learning and deep learning algorithms, dictionary learning is a "white-box" algorithm involving only linear transformations, and building a dictionary learning model requires only an empirical definition of the total number of atoms. Therefore, in this paper, two dictionary learning anomaly detectors were established for mineral prospectivity modeling based on the least angle regression-Lasso (LARS-Lasso) algorithm and the iterative shrinkage-thresholding algorithm (ISTA). The following five-step procedure was proposed for mineral prospectivity modeling using the dictionary learning techniques: (a) an overcomplete dictionary is constructed based on the input data; (b) each data point is transformed into sparse coefficients according to the overcomplete dictionary; (c) the sparse representation of each data point is calculated based on the overcomplete dictionary and the sparse coefficients; and (d) the Euclidean norm of the difference between each data point and its sparse representation is calculated and used as the mineral potential of the data point. The dictionary learning models were established to model gold prospectivity in the Jinchanggouliang district, Inner Mongolia, China, and compared with the logistic regression model and one-class support vector machine model in gold exploration targeting. The result shows that (a) the performances of the dictionary learning models are no less than that of the logistic regression (LGR) model and better than that of the one-class support vector machine (OCSVM) model, and (b) the gold prospective areas differentiated by the established models are strongly consistent with geological and metallogenic characteristics in the study area. Therefore, the dictionary learning algorithms are high-performance mineral prospectivity modeling techniques. It is worth to further test the effectiveness of the dictionary learning algorithms for different types of mineral deposits in different areas in mineral exploration targeting. [ABSTRACT FROM AUTHOR]

[Display omitted] • One high-εHf and two low-εHf domains in the Argun massif indicate the Neoproterozoic and Mesoproterozoic to Neoproterozoic crustal zones, respectively. • Transition of magma source from the juvenile crust to ancient crust from south to north during the Mesozoic. • The composition and structure of the crust control the metal associations, deposit types, and localization of ore deposits. The Argun massif is an important micro-continent in the eastern Central Asian Orogenic Belt and hosts a wide variety of Mesozoic hydrothermal Cu(–Mo), Pb–Zn–Ag, and Au deposits such as Wunugetushan Cu(-Mo) and Jiawula Pb–Zn–Ag deposits. In this paper, we integrate geological and zircon U–Pb–Hf isotopic data from Mesozoic Argun igneous rocks to elucidate the crustal architecture, and any spatial–temporal and genetic links with the regional metallogeny. Our results indicate that the porphyry Cu–Mo deposits in the massif were mainly developed in the zones with high-εHf(t) values and Neoproterozoic T DM c ages, representing juvenile lower crustal components. The epithermal Pb–Zn–Ag deposits were mostly developed in zones with variable εHf(t) and Mesoproterozoic to Neoproterozoic T DM c values, representing magma source with reworked ancient or juvenile lower crustal components. In contrast, the major mesothermal and epithermal Au deposits are associated with magmatic rocks emplaced in low-εHf(t) and high-T DM c domains, representing reworked Mesoproterozoic ancient crustal components. [ABSTRACT FROM AUTHOR]

• Pyrite hosting visible gold is low in Au and As. • Gold-bearing pyrite was subject to brittle rather than ductile deformation. • Visible gold in pyrite did not result from remobilization of lattice gold. • Visible gold in pyrite was introduced by evolved ore fluids after host pyrite. Pyrite (FeS 2) is one of the most common hosts for gold (Au) in different types of gold deposits, including visible and invisible gold. For visible gold in pyrite, it remains unclear whether it resulted from remobilization of invisible gold in the gold-hosting pyrite or from external input. This paper reports a case study from the Zhaoxian gold deposit, which is the deep extension of the well-known Jiaojia gold deposit, in the Jiaodong gold province. The texture and composition of Au-bearing pyrite from the Zhaoxian deposit were studied with petrographic, Electron Back-Scattered Diffraction (EBSD) mapping, and Laser Ablation – Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS) methods. Four types of pyrite (Py-1 to Py-4), corresponding to four generations of veins, i.e., the pre-ore V1, syn -ore V2 and V3, and post-ore V4, were distinguished. Py-2 is volumetrically the most abundant among the four, and is the main host of visible gold. LA-ICP-MS analyses of pyrite indicate that gold contents in most analysis points are below the detection limit, with measured Au contents ranging from 0.02 to 0.17 ppm (median 0.09 ppm) in Py-1, and 0.03 to 2.45 ppm (median 0.07 ppm) in Py-2. EBSD analyses indicate that pyrite (Py-2) display brittle deformation features including microstructures, lattice dislocation, and grain boundary displacement. Visible gold in Py-2 occurs in micro-fractures, cavities, and grain boundaries. The generally low contents of Au in pyrite, including Py-2, and the brittle deformation features, suggest that the visible gold grains did not result from remobilization of invisible gold from pyrite. Rather, the majority of gold was introduced by fluids after the formation of the gold-hosting pyrite. These fluids were derived from the same sources as those precipitating the gold-hosting pyrite, but were more evolved and enriched in Au. Circulation of these auriferous ore-forming fluids in microfractures of pyrite and interstitial space resulted in precipitation of visible gold. [ABSTRACT FROM AUTHOR]

• Tectonic uplifting and denudation events correspond to uranium mineralization. • The large-scale deposits result from the superposition of multiple tectonic events. • A triad prediction method system of sandstone-type uranium deposit is established. The controlling effect of tectonic uplift and denudation on uranium mineralization has been much studied previously, and its important contribution to uranium mineralization has been fully recognized. However, no systematic theory and methodological criteria for uranium prospecting has been summarized. Here we present the results of an in-depth study of the characteristics and formation process of typical sandstone-type uranium deposits in the northern basin of China, and conclude with a uranium metallogenic theory: tectonic uplift and denudation events are the driving force for the formation of sandstone-type uranium deposits (or even mudstone-type uranium deposits). The stage of tectonic uplift and subsequent denudation events since the formation of the target layer determines the mineralization stages: the greater the intensity and duration of uplifting and denudation events, the larger the scale of uranium mineralization. The formation of large and mega-scale sandstone-type uranium deposits requires multiple stages of tectonic uplift and denudation events superimposed in the same direction. Single or polydirectional tectonic uplift and denudation events often do not form industrial uranium deposits. In this paper, a three-step method to predict the occurrence of sandstone-type uranium deposits is established, which includes (1) determining the tectonic framework division of the sedimentary basin being investigated, (2) a burial and denudation history study, and (3) apatite fission-track simulation of the erosion source area. Focusing on the tectonic evolution and the rapid uplift and denudation events of the basin and the erosion source area is critical (the tectonic evolution of the two areas usually is closely coupled). The desired result can be achieved only by combining the aforementioned theory with basic principles of sandstone-type uranium mineralization, and treating uranium mineralization as a result of a special tectonic event. The theory deepens the understanding of sandstone-type uranium mineralization, and the method plays a role in the rapid evaluation of sandstone-type uranium deposits in sedimentary basins, and it can be extended to research and prediction in other basins. [ABSTRACT FROM AUTHOR]