Stages Of Mineralization Research Articles

Evolution of skarn to quartz-vein mineralization: Insights from the Tongshanling Cu–Pb–Zn deposit, South China

The Tongshanling Cu–Pb–Zn deposit, situated within the Qin-Hang intra-continental porphyry-skarn metallogenic belt in South China, presents a valuable case study of intrusion-related ore systems. This deposit is characterized by skarn mineralization closely associated with subsequent quartz-vein sulfide mineralization. While considerable research has been devoted to understanding the origin and evolution of the intrusions and mineralization processes, limited attention has been given to elucidating the relationship between the skarn and quartz-vein mineralization, along with the physicochemical conditions governing their formation. Here, we conducted a comprehensive mineralogical and isotopic investigation of sulfides, and a thorough analysis of fluid inclusion assemblages. We aimed to discern disparities in the sources of ore-forming materials, formation temperature, sulfide fugacity, and precipitation-alteration mechanisms of hydrothermal fluids for these two distinct orebodies. Although same sulfide species including arsenopyrite, pyrite, chalcopyrite, and sphalerite, some silicate minerals such as garnet, chlorite, and epidote are exclusive to the skarn orebodies and absent in the quartz veins.The homogeneous temperatures of fluid inclusions in the skarn orebody, ranging from the early to late stages of evolution, decrease from ∼310 to ∼290 °C. Simultaneously, salinity varies from 5.5 to 3.1 wt% NaCl eqv. In the quartz vein mineral body, the temperature reduction is more pronounced, decreasing from ∼270 to 186 °C, with salinity ranging from 3.6 to 1.4 wt% NaCl eqv. Sphalerite geothermometer indicates that peak hydrothermal fluid temperature in the skarn orebodies (∼300–340 °C) was relatively higher than that in the quartz-vein orebodies (<300 °C). Nevertheless, temperatures in both hydrothermal fluid systems declined as mineral precipitation proceeded, corresponding to a decrease in sulfur fugacity. The final stage of sphalerite represents the lowest temperature, salinity and sulfur fugacity with associated quartz displaying the lowest salinity across the entire hydrothermal fluid spectrum at the Tongshanling deposit, suggestive of meteoric water incorporation. This study delves into the multifaceted history of mineralization at the Tongshanling deposit, providing a fresh perspective on the origin and evolutionary relationships of Cu-polymetallic deposits associated with intrusions, particularly those involving multiple stages of mineralization in skarns and quartz veins, contributing to a better understanding of similar deposits worldwide.

Mineralogy and Geochemistry of the Mupane and Shashe Gold Deposits of the Tati Greenstone Belt (NE Botswana): Implications for Mineral Deposit Models and Exploration

Abstract The Archean Tati greenstone belt is located at the southwestern margin of the Zimbabwe craton (northeast Botswana) and hosts numerous Cu-Ni ± platinum group element (PGE) and Au ± Ag occurrences and deposits. Gold occurrences/deposits are poorly studied, and key questions pertaining to their genesis remain unclear, including the mode of occurrence(s) of gold, the relative timing of gold introduction with respect to the evolution of the greenstone belt, the number of gold mineralization events, the alteration patterns, and the relationships between each alteration pattern and gold mineralization. A detailed study that includes sulfide and gold grain chemistry using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA), respectively, and X-ray diffraction (XRD) of mineralized rock samples of three Tati greenstone belt gold deposits was carried out to constrain the genesis of gold mineralization and formulate exploration guidelines in the Tati greenstone belt. Gold in the Tati greenstone belt is the result of multiple events, is mainly associated with arsenopyrite, pyrite, and sphalerite, and occurs as (1) microinclusions within sulfides, (2) intergrowth with sulfides, (3) minute particles (&amp;lt;2–10 μm) within the silicate matrix, (4) microfractures and microvug infills, and (5) lattice-bound and sulfide-hosted refractory gold. The first gold event (as electrum) is premetamorphic and associated with sphalerite-quartz veins. The second stage is a postmetamorphic high-grade gold event that is accompanied by extensive carbonatization and propylitization of host rocks. The third stage of gold mineralization is marked by the dissolution of gold in the early formed stages 1 to 2 and subsequent reprecipitation within cracks, fractures, and vugs. Auriferous pyrite composition suggests that Au-bearing mineralizing fluids are predominantly of magmatic origin and that their physicochemical compositions changed during the mineralization process, as supported by chemically zoned Au-bearing arsenopyrite, various alteration types containing gold, and variation in gold fineness across the several gold deposits in the Tati greenstone belt. Gold deposition in the Tati greenstone belt mainly occurred through sulfidation, as indicated by the closest spatial association between gold and Fe-bearing sulfides and ferromagnesian silicates. Gold in the Tati greenstone belt is closely correlated with As, Sb, Pb, Bi, Ni, Hg, Tl, Cd, In, Mo, W, Zn, and Te and moderately to weakly associated with Sn, Se, Cr, Co, Ge, Cd, Mn, V, Ga, and Ag. The correlation between Au and fluid mobile elements, i.e., Te, Sb, Se, As, Hg, and Bi, can be used as a vectoring tool during the exploration of gold within the Tati greenstone belt, as these elements likely form halos that are much broader than the primary footprint of gold mineralization.

Genesis of the Nuri Cu‐W‐Mo Deposit, Tibet, China: Constraints from in situ Trace Elements and Sr Isotopic Analysis of Scheelite

AbstractThe Nuri deposit is the only Cu‐W‐Mo polymetallic deposit with large‐scale WO3 resources in the eastern section of the Gangdese metallogenic belt, Tibet, China. However, the genetic type of this deposit has been controversial since its discovery. Based on a study of the geological characteristics of the deposit, this study presents mineralization stages, focusing on the oxide stage and the quartz‐sulfide stage where scheelite is mainly formed, referred to as Sch‐A and Sch‐B, respectively. Through LA‐ICP‐MS trace element and Sr isotope analyses, the origin, evolutionary process of the ore‐forming fluid and genesis of the ore deposit are investigated. Scanning Electron Microscope‐Cathodoluminescence (SEM‐CL) observations reveal that Sch‐A consists of three generations, with dark gray homogenous Sch‐A1 being replaced by relatively lighter and homogeneous Sch‐A2 and Sch‐A3, with Sch‐A2 displaying a gray CL image color with vague and uneven growth bands and Sch‐A3 has a light gray CL image color with hardly any growth band. In contrast, Sch‐B exhibits a ‘core‐rim’ structure, with the core part (Sch‐B1) being dark gray and displaying a uniform growth band, while the rim part (Sch‐B2) is light gray and homogeneous. The normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore‐forming fluid in the Nuri deposit originated from granodiorite porphyry and, later on, some country rock material was mixed in, due to strong water‐rock interaction. Combining the O‐H isotope data further indicates that the ore‐forming fluid in the Nuri deposit originated from magmatic‐hydrothermal sources, with contributions from metamorphic water caused by water‐rock interaction during the mineralization process, as well as later meteoric water. The intense water‐rock interaction likely played a crucial role in the precipitation of scheelite, leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz‐sulfide stage, while also causing a gradual decrease in oxygen fugacity (fO2) and a slow rise in pH value. Additionally, the high Mo and low Sr contents in the scheelite are consistent with typical characteristics of magmatic‐hydrothermal scheelite. Therefore, considering the geological features of the deposit, the geochemical characteristics of scheelite and the O‐H isotope data published previously, it can be concluded that the genesis of the Nuri deposit belongs to porphyry‐skarn deposit.

In Situ Trace Element and S-Pb Isotope Study of Pyrite from the Denggezhuang Gold Deposit in the Jiaodong Peninsula—Insights into the Occurrence of Gold and the Source of Ore-Forming Materials

The Jiaodong gold province is one of the most important gold fields globally and the largest in China. The Denggezhuang gold deposit is situated in the eastern portion of the Muping metallogenic belt, within the Jiaodong gold province. Despite many recent investigations, detailed mineralogical studies, particularly on auriferous minerals such as pyrite, are lacking. Therefore, further constraints on the occurrence mode and source of gold are necessary for this deposit. This study employed in situ laser ablation (multi-collector) inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) trace element and sulfur-lead isotopic analyses on pyrite at different stages. The aim was to reveal the occurrence status of various trace elements within Denggezhuang pyrite and to trace the complete evolution process of multi-stage fluids at Denggezhuang, elucidating the sources of gold mineralization. Four generations of pyrite in chronological order, Py-1, Py-2a, Py-2b, and Py-3, were identified via petrographic and backscattered electron (BSE) image analyses. Using in situ LA-MC-ICP-MS, we found that Co and Ni are most abundant in Py-1, while Py-2b is rich in As, Au, Ag, Pb, and Zn, reflecting the evolution of the mineralizing fluids in different mineralization stages. Py-2b contains a significant amount of invisible lattice gold, which migrates and precipitates within fluids rich in As. The in situ LA-MC-ICP-MS S-Pb isotopic analysis of pyrite indicates a relatively consistent source of ore-forming materials across different stages. Additionally, the S-Pb isotope characteristics resemble those of widely distributed coeval mafic dikes. Therefore, we propose that a water-rich, fertile, and deep-seated mafic magmatic system might have provided fluids, materials, and heat for mineralization.

The gold-telluride connection: Evidence for multiple fluid pulses in the Jinqingding telluride-rich gold deposit of Jiaodong Peninsula, Eastern China

The mechanism of gold migration, enrichment, and precipitation in forming world-class gold deposits has been a topic of wide interest, particularly where these deposits are abundant in tellurides. The Jiaodong Peninsula in eastern China hosts some of the world-class gold deposits among which the Jinqingding deposit is one of the best examples with substantial telluride mineralization and thus provides opportunity to investigate the genetic connection between tellurium and gold mineralization. The orebody in this deposit is hosted in the NE-NNE-trending Jiangjunshi-Quhezhuang fault with the Jurassic Kunyushan granitic pluton as wall rock. The deposit involved three mineralization stages as inferred from assemblages and crosscutting relationships between veins. These stages are: (I) pre-ore gold-poor quartz-pyrite veins, (II) main ore auriferous quartz-pyrite-Te/Bi-minerals ± sphalerite ± chalcopyrite ± barite ± marcasite veins, and (III) post-ore quartz-calcite veins. We present here the textural, isotopic, and geochemical variations of different stages/generations of pyrite based on scanning electron microscopy-energy dispersive spectroscopy (SEM–EDS), electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS).Pyrite in the Jinqingding deposit displays distinct characteristics. Py1a shows a porous and dissolution-reprecipitation texture in the core, whereas Py1b exhibits a smooth and flat rim. Geochemical analysis reveals contrasting elemental compositions, with Py1a characterized by low Au (avg. 0.14 ppm), As (avg. 15.57 ppm), Ag (avg. 17.71 ppm), and Te (avg. 19.22 ppm) contents, but elevated Co (avg. 1068.10 ppm) and Ni (224.12 ppm) concentrations, and variable sulfur isotopic composition (δ34SV-CDT = 9.54‰–12.12‰). Conversely, Py1b displays increased concentrations of these elements and a more concentrated δ34SV-CDT value (11.99‰–12.23‰), possibly associated with weak coupled dissolution-reprecipitation (CDR) processes. In Stage II, pyrite can be further categorized into two generations: the porous core (Py2a) and the smooth periphery (Py2b). Notably, Stage II exhibits increased contents of Au (Py2a: avg. 0.47 ppm; Py2b: avg. 5.57 ppm), As (Py2a: avg. 1265.20 ppm; Py2b: 1049.46 ppm), Ag (Py2a: avg. 5.43 ppm; Py2b: avg. 65.23), and Te (Py2a: avg. 21.47 ppm; Py2b: avg. 51.66 ppm), δ34SV-CDT value exhibits minor changes (Py2a: 11.48‰–13.05‰; Py2b: 11.79‰–12.80‰). These changes potentially indicate the involvement of a fluid pulse characterized by low fO2: −34.9 to −30.2, medium fTe2: −14.7 to −10.9 and fS2: −11.4 to −6.9. Despite the dissolution-reprecipitation textures present in the ores, gold did not undergo remobilization, except for a possible weak contribution in Stage II. The presence of abundant Bi/Te-minerals underscores the significant role of low-melting point chalcophile elements in gold migration and enrichment. By compiling and analyzing sulfur isotopic composition of gold deposits across the entire Jiaodong Peninsula, which shows the reduction of marine sulfates as a crucial mechanism for sulfur enrichment. We conclude that the Jinqingding gold deposit, characterized by abundant tellurium, along with episodic pulses of ore-forming fluids, and exhibit subtle distinctions compared to other gold deposits within the Jiaodong Peninsula.

Textures and trace element geochemistry of pyrite in Gaoloushan ore section of the Yangshan gold belt, West Qinling: Implications for ore genesis

The Devonian Sanhekou Group phyllite in the Yangshan gold belt includes multiple stages of pyrite development, and Au is mainly distributed within the pyrite. Bodies within the Gaoloushan ore section of the gold belt are located in the broken and altered carbonaceous phyllite and granitic rock dykes, where quartz vein-type gold ores are more common as compared to other ore sections (Anba, Getiaowan). Studying the trace element distribution characteristics of gold-bearing and non-gold-bearing pyrite can constrain the evolution of ore-forming fluids and the types of ore deposit genesis. Based on detailed fieldwork and microscopic identification, 48 pyrite samples from the 69th exploration line of the Gaoloushan ore section were analyzed in situ by LA-ICP-MS. The following conclusions were drawn: (1) The gold-bearing pyrite formed during the ore-forming stage while the non-gold-bearing pyrite formed during the sedimentary and metamorphic period. The morphology of the pyrites differs, with gold-bearing pyrite mainly characterized by medium-fine grains, impregnation, fine veins, and reticulate structure, with crystal morphology mainly pentagonal dodecahedra or pentagonal octahedra, whereas non-gold-bearing pyrite is mainly characterized by a medium or medium-coarse grains, with stellate, strawberry, or cluster structures, and crystal morphology mainly in the form of cubes or pentagonal octahedra; (2) The As and Te content of the sedimentary pyrite is low, locally below the detection limit, and the Co and Ni contents and ratios vary greatly, with a distribution of 117–945 ppm and ratio distribution of 0.11–1.92. Pyrite from the ore-forming stage is primarily characterized by high As, Pb, Co, Ni, Cu, Sb, Zn, and Se concentrations, with Bi, Au, and trace amounts of Tl, Te, and Sn observed in later formations; (3) Au and As are positively correlated. The average Au content of 60.53 ppm in pyrite from granite dykes is higher than the average Au 15.97 ppm in carbonaceous phyllite. Pyrite particles with Au contents below the detection limit are sourced in carbonaceous phyllite. In addition, the higher As enrichment is observed in pyrite from granite dykes, averaging 35 770.60 ppm with a maximum value of 72 930.19 ppm. In comparison, the average As content in carbonaceous phyllite is 8974.66 ppm, with a maximum of 69 800.50 ppm, and the Au-As diagram indicates that gold in the Gaoloushan ore section is mainly in the form of solid solution gold within the pyrite lattice; (4) Statistical analysis of the Co/Ni ratio variation in the different lithologies and pyrite stages reveals an initial increase followed by a decrease. The median Co/Ni ratio variations during the mineralization stages of Py1s (0.51–0.7), Py1m (1.35–2.25), Py2 (1.43–1.87), Py1-2 m (1.53), Py2a (1.59), Py2b (1.4), Py2s (1.2), Py2m (1.63), and Py3 (0.19–1.40) suggest that magmatic-hydrothermal fluids dominated during the early stage of mineralization in the gold belt and metamorphic fluids during the main mineralization stage, with deep-seated metamorphic fluids playing a significant role in the late mineralization stage. The varying proportions of ore-forming fluids are likely to have been crucial in controlling gold mineralization in the Yangshan gold belt.

Evaluation of data collection bias of third molar stages of mineralisation for age estimation in the living

Abstract Age assessment of the living is a fundamental procedure in the process of human identification, in order to guarantee fair treatment of individuals, which has ethical, civil, legal, and medical repercussions. The careful selection of the appropriate methods requires evaluation of several parameters: accuracy, precision of the method, as well as its reproducibility. The approach proposed by Mincer et al. (1993), adapted from Demirjian et al. (1973), exploring third molar mineralization, is one of the most frequently considered for age estimation of the living. Thus, this work aims to assess potential bias in the data collection when applying the classification stages for dental mineralization adapted by Mincer and colleagues (1993). A total of 102 orthopantomographs (OPGs), of clinical origin, belonging to individuals aged between 12 and 25 years (x ̅=20.12 years, SD = 3.49 years; n = 65 females, 37 males, all of Portuguese nationality) were included and a retrospective analysis performed by five observers with different levels of experience (high, average, and basic). The performance and agreement between five observers were evaluated using Weighted Cohen’s Kappa and the Intraclass Correlation Coefficient. To access the influence of impaction on third molar classification variables were tested using ordinal logistic regression GENLIN. It was observed variations in the number of teeth identified among the observers but agreement levels ranged from moderate to substantial (0.4 to 0.8). Upon closer examination of the results, it was observed that although there were discernible differences between highly experienced observers and those with less experience, the gap was not as significant as initially hypothesized, and a greater disparity between the classifications of the upper (0.24 to 0.49) and lower third molars (&amp;gt;0.55) was observed. When bone superimposition is present, the classification process is not significantly influenced, however, variation in teeth angulation affects the assessment. The results suggest that with an efficient preparation, the level of experience as a factor can be overcome. Mincer and colleague’s classification system can be replicated with ease and consistency, even though the classification of upper and lower third molars presents distinct challenges.

Evolution of orogenic gold mineralization in the southern and eastern framing structures of the Siberian craton

The purpose of the research is to compare the evolution of gold ore mineralization in the structures of the Baikal-Patom and Verkhoyansk-Kolyma marginal continental orogenic belts that arose on the passive margin of the Siberian continent in the Neoproterozoic-Paleozoic and Paleozoic-Mesozoic, and hosting the largest gold deposits in Russia. The similarities are noted as they reveal themselves in the characteristics of the mineralization stages, and in the typomorphism of pyrite that is the main mineral of ore formations. The study demonstrated the role of polychronic orogenic events of the Paleozoic and late Mesozoic times, which led to the formation of large fold belts in the development of large-scale gold mineralization of the southern and eastern framing of the Siberian craton. These events caused precious metals to mobilize and redistribute from precious metal-rich stratigraphic horizons as corresponding orogenic plutonometamorphic belts were formed. A comparative analysis of the Paleozoic-Mesozoic and Neoproterozoic-Paleozoic metallogenic profiles of the southern and eastern margins of the Siberian craton demonstrates the influence of the formation processes of orogenic gold mineralization, regardless of the composition of the host strata and mineralization age. General metallogenic characteristics of paleogeodynamic formation settings of noble metal mineralization of the orogenic-type, regardless of its age, can serve as the basis for geological-genetic and forecasting predictions as well as for the development of integrated assessment criteria for their prospects within the regions under investigation.

Characteristics and evolution of quartz-calcite-sulfide veins in the Nazca-Ocoña belt, Peru

The Nazca-Ocoña metallogenic belt in southern Peru host about 70 recognized Au-Ag and base metal (Pb-Cu-Zn) deposits such as Orión, Caravelí, Ishihuica, Calpa, Arirahua, Mollehuaca, and San Juan de Chorunga. These deposits are spatially associated with Cretaceous intrusive rocks of the coastal Batholith in a zone that extends more than 350 km along the Central to Southern part of Peru. Gold and silver are structurally controlled in mineralized NW-SE, N-S and W-E-trending fault-fill veins that are less than one-meter wide, crosscutting granodiorite and diorite bodies. The origin of the veins is still debated, and they may be classified as intrusion-related gold deposits (IRGD), orogenic or mesothermal deposits. In this study, we focus on two representative deposits in the Nazca-Ocoña metallogenic belt: Mollehuaca and San Juan de Chorunga. At both sites, the mineralization is composed of quartz-calcite sulfide veins hosted in Cretaceous Coastal Batholith intrusions. Petrographic and chemical analyses on pyrite were performed with field-emission scanning electron microscopy (FE-SEM), electron microprobe analysis (EMPA), nano-scale secondary ion mass spectrometry (NanoSIMS), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).Native gold and Au-rich silver are disseminated throughout the veins as micro to sub-micron inclusions in pyrite and chalcopyrite, and in pyrite as cavity and fracture fill. The are three pyrite generations and these have complex internal zonation and are host to precious (Au, Ag) and base metals (Co, Ni, Cu) metals, and also metalloids (As, Sb) as lattice-bound impurities and micron inclusions. The San Juan de Chorunga pyrite has δ34S values ranging from 0.4 to 1.4 ‰, and the Mollehuaca pyrite δ34S from 5.8 to 7.4 ‰. In both San Juan de Chorunga and Mollehuaca, the highest Au concentrations occur in pyrite zones with the heaviest δ34S values. Fluid inclusion petrography of these veins shows recrystallized, wispy quartz with implosion and explosion fluid inclusion textures, indicative of pressure variations during quartz vein formation. The presence of CO2 in these inclusions requires mid-crustal pressure conditions. However, the main stage of gold mineralization occurs with carbonate, chlorite, and euhedral quartz crystals lacking post-entrapment recrystallization textures or CO2. Our observations suggest that most of the gold in these veins formed in association with a shallower hydrothermal event, potentially in association with the emplacement of batholiths and shallower intrusions in the Late Cretaceous.

Characteristics of Ore-Forming Fluids and Genesis of the First Mining Area and Eastern Ore Section of the Pulang Porphyry Copper Deposit, Southeastern China: A Comparative Study

The Pulang copper deposit, formed in the Late Triassic, is the largest porphyry Cu-Mo-Au deposit in the eastern Tethys, and its genetic type and mineralization potential have received widespread attention. Identifying the characteristics of ore-forming fluids and the sources of ore-forming materials in the deep and peripheral ore bodies of Pulang is particularly important for constructing a complete porphyry copper mineralization system. Based on detailed core logging and geological observations, this article provides extensive petrographic, fluid inclusion micro-thermometry, laser Raman spectroscopy, and H-O-S isotope data on the veins of the main mineralization stage (B veins) in the first mining area and eastern ore section of the Pulang porphyry copper deposit. The genetic correlation between the eastern ore section and the first mining area is clarified, and their mineralization potential is inferred. The results indicate that the deep vein bodies in the first mining area exhibit multi-stage characteristics, and the fluid in B veins exhibits both high-temperature and salinity characteristics. The magma-derived early ore-forming fluids underwent processes such as boiling and experienced immiscibility during meteoric water mixing, which could be the primary mechanism of the precipitation of Cu, Mo, Au, and other metals. The outer eastern ore section is located in a medium-to-low-temperature hydrothermal mineralization zone far from the mineralization center. This outer eastern ore section is a distant part of the magmatic–hydrothermal system of the first mining area.

Late Triassic E-W striking shear zone and its implication on gold mineralization in the Xiaoqinling area, eastern China

The Xiaoqinling area is located in the eastern part of the Qinling Orogen and experiences early and late Mesozoic gold mineralization controlled by structural deformation. The relationship between the two stages of mineralization and the orogenic process of the Qinling Orogen is unclear. We investigated the deformation and alteration of E-W striking veins in the Xiaoqinling area. The geometric features revealed that all the veins developed within the E–W-striking Guanyintang brittle–ductile shear zone. The vein was subparallel to the shear zone, dipped at 30°–60°, and had a wave-like appearance. The Guanyintang shear zone underwent three deformation stages: sinistral shearing (D1), dextral thrusting (D2), and sinistral normal faulting (D3). The development of ore-bearing quartz veins was controlled by deformation during D2, and the auriferous pyrite and minor chalcopyrite developed along the shear foliations. Re-Os dating of the molybdenite revealed a well-constrained isochron age of 230.2 ± 2.6 Ma, indicating the E-W striking shear zone developed in Late Triassic. This early Mesozoic shearing deformation in Xiaoqinling represents the early Mesozoic metallogenesis is correlated with the collisional orogeny of the Qinling orogen.

The role of magmatic versus metasomatic processes in Ta-Nb mineralization at the Jiabusi Deposit, Inner Mongolia: Evidence from textural and chemical features of rare metal minerals and mica

The exact role magmatic versus metasomatic processes play in Ta-Nb mineralization is a question that has been debatable for several decades. The Jiabusi deposit is chosen to address this question, for its ample endowments of a variety of Ta-Nb oxides and mica in the various rock types that could provide insights into the whole evolutional history of ore-forming processes during magmatic-hydrothermal evolution. Textural and chemical evidence suggests that Fe-mica in the Fe-mica granite and pegmatitic portion is magmatic, indicating that the co-precipitated columbite-group minerals (CGM) and pyrochlore-supergroup minerals (PSM) are also magmatic. In the lepidolite granite and aplite, on the other hand, two stages of mineralization occured, represented by unzoned CGM that are in equilibrium with lepidolite, snowball quartz, and fluorite that all have a metasomatic origin and subsequent CGM/PSM overgrowths that co-precipitated with metasomatic Cs-lepidolite and saccharoidal albite. These CGM overgrowths have 1–2 time(s) higher Ta/(Nb + Ta) values than the preceded CGM, generating a clear compositional gap between them. Both stages of CGM and CGM/PSM precipitated from a hydrosilicate liquid (HSL), the partial migration of which results in the disequilibrium textures observed. The lepidolite granite is largely a metasomatic rock, the protolith of which has been obscured by intense metasomatism governed by the HSL. This HSL, however, is mainly constrained to the lepidolite granite but a few migrated into the Fe-mica granite. This is the main reason for the different mineralizing styles and intensities between the two rock types.

Dental and skeletal maturation of Chinese male children with unilateral cleft lip and palate.

The aim of this study was to determine whether the relationship between dental age (DA), cervical stage (CS) and chronological age (CA) in Chinese male children with unilateral cleft lip and palate (UCLP) is similar to that of children without clefts. Panoramic and cephalometric radiographs of 105 male UCLP patients, aged from 8 to 16 years, were collected and compared to 210 age-matched healthy control males. The Demirjian and cervical vertebral maturation (CVM) methods were used to visually examine the radiographs and Spearman's correlation analysis was used to identify differences between the two groups with regards to CS, DA and CA. There was a significant positive correlation between DA and CA in both groups and the mean CA-DA difference was significantly higher in children with UCLP when compared to controls (0.319 vs. 0.003, p < 0.05). A significant delay in tooth development was detected in UCLP children from 10 to 12 years-of-age. Both the UCLP and control groups showed high correlations between CS and DA. Calcification stage D appeared only before CS3; however, from CS5 to 6, all teeth have almost completed their maturation phase. Chinese male UCLP patients are likely to experience delayed tooth development compared to healthy controls, especially during the fast-growing period. Evaluating the stages of tooth mineralization could represent a rapid method to assess growth potential.

In situ sulfur isotope analysis of pyrite from the Ezuri Kuroko‐type volcanogenic massive sulfide deposit, northeastern Japan: Contribution of microbial sulfate reduction to initial sulfide mineralization

AbstractVolcanogenic massive sulfide (VMS) deposits are ancient analogues of seafloor massive sulfide (SMS) deposits. The importance and contribution of microbial activity during initial mineralization has recently been recognized in both VMS and SMS deposits. Here, we report in situ sulfur isotope compositions (δ34S) of pyrite from the Ezuri Kuroko‐type VMS deposit in northeastern Japan as determined by secondary ion mass spectrometry. During the evolutionary process of sulfide mineralization, pyrite textures changed from framboidal to colloform to euhedral. Initial framboidal pyrite had highly negative δ34S values down to −31.8‰ (average ± 1SD = −18.8‰ ± 13.0‰; n = 21), banded colloform pyrite exhibited medium δ34S values (−11.7‰ ± 10.4‰; n = 8), and euhedral pyrite displayed the highest average δ34S value of +2.7‰ ± 1.6‰ (n = 5); thus, δ34S varied as different textures of pyrite were produced during mineralization. The maximum isotopic fractionation between framboidal pyrite and past seawater sulfate (δ34S ca. +20‰) is −52‰; such values can be produced only by microbial sulfate reduction (MSR) in an open system. Framboidal pyrite with a low δ34S value is observed at the centers of sulfide‐rich areas within polished sections and has often been replaced by later sulfide minerals (sphalerite, galena, and chalcopyrite); thus, our S isotope data from the Ezuri pyrite reveal that sulfur derived from MSR induced and acted as a nucleation point for later sulfide mineral growth. Combined with previously reported data, our results endorse the importance and universality of MSR‐derived sulfur during the initial mineralization stage of both VMS and SMS deposits.

The Occurrence and Chemical Composition of Bismuth-Bearing Minerals in the Niuxingba-Liumukeng Ag-Pb-Zn Deposit, Jiangxi Province, South China

The Niuxingba-Liumukeng deposit, located in the Yinkeng ore field (Jiangxi province, South China), is a typical Ag-Pb-Zn deposit hosted in the Yudu-Ganxian metallogenic belt. Based on the field investigation and mineralogical studies, the mineralization of this deposit can be divided into three stages: quartz-pyrite-arsenopyrite stage (I), quartz-galena-sphalerite-sulfosalt stage (II), and quartz-carbonate stage (III), with stage II being the main Ag mineralization stage. In this contribution, we reported the occurrence of bismuth-bearing minerals in this hydrothermal deposit and its implications for ore formation. Based on the results of electron microprobe analyses, we infer that the dominant occurrence of bismuth at Niuxingba-Liumukeng is primarily marked by solid solutions within the crystal lattice of galena and as visible independent bismuth-bearing minerals. The independent bismuth minerals consist of berryite [Pb3(Ag,Cu)5Bi7S16], emplectite (CuBiS2), and aikinite (PbCuBiS3). Most bismuth minerals replace chalcopyrite or fill in the cracks of pyrite and chalcopyrite. Meanwhile, we found a large number of Bi-bearing minerals closely coexisting with Ag-bearing minerals, indicating that bismuth may have played a crucial role in silver deposition from hydrothermal fluids. We considered that the existence of bismuth-rich melts associated with the ore-forming hydrothermal systems could help to promote the enrichment and precipitation of silver to form economic ores.

Superimposed multi-stage mineralization in the Qingchengzi Pb-Zn ore district, North China: Evidence from geochronology and sulfide geochemistry

The Qingchengzi Pb-Zn polymetallic ore district in northern China records two stages of Pb-Zn mineralization in the Paleoproterozoic and Mesozoic, respectively. The Paleoproterozoic sedimentary-metamorphic stage (stage I) of mineralization was primarily recorded by stratiform ores, and the Mesozoic magmatic-hydrothermal stage (stage II) of mineralization mostly formed vein-type ores. The apatites coexisting with the stage I sulfides yield U-Pb isotopic ages of (1882–1857 Ma), corresponding to the regional metamorphism pervaded in the Paleoproterozoic in the Liaodong region. Zircons from a granite porphyry that is spatially associated with the stage-II mineralization have a U-Pb age of 228.5 ± 5.8 Ma.Stage-I fine-grained sulfides (Py1a and Sp1a) are of SEDEX origin and the fluid is fertile in metals such as Co, Ni, Zn, As, Mn and V. The metals are likely to be sourced from the Liaohe Group, which contains high concentration of those metals. Stage-I recrystallized sulfides (Py1b and Sp1b) show trace elements such as Co, Ni, Cu, As and Au of pyrite and the Cu, Cd, In, Ag, Sb of sphalerite were remobilized out from their crystal lattice under metamorphism. Stage-II sulfides (Py2 and Sp2) are more enriched in Au, As, Cu, Ag, Sb, Pb compared to stage-I sulfides. LA-ICP-MS mapping reveals multigenerational texture of Py2 which features a Cu and Zn enriched core (Py2a) and an overgrowth rim (Py2b) of enrichment in Au, As, Co and Ni. The compositionally distinct core and rim presumably suggest that two episodes of magmatic fluids are involved in the formation of stage-II sulfides. The sedimentary pyrite from Liaohe Group and the stage-I sulfides have δ34S value in the ranges of 10.4–17.04 ‰ and 4.10–9.37 ‰, respectively, suggesting that sulfur was probably derived from seawater sulfate reduction. The sulfur isotopes of stage-II sulfides (δ34S = 4.10–9.02 ‰) reflects a mixing of magmatic sulfur with sulfur leached from meta-volcanic-sedimentary source. This process was associated with the upward migration of magmatic hydrothermal fluids and subsequent fluid-rock interaction, which leached heavy sulfur isotopes along with Cu, Zn, Co, Ni, V metals from wall rocks of mica schist from the Dashiqiao and Gaixian Formations. Integrated mineral assemblage, sulfide texture, trace element and sulfur isotope signatures and geochronological constraints reveal the primary Paleoproterozoic SEDEX mineralization was intensively overprinted by later metamorphism and Mesozoic magmatic hydrothermal events for the Pb-Zn deposits in the Qingchengzi ore district.

Ore genesis of the Bayanbaolege Ag-Pb-Zn deposit, NE China: Constraints on LA-ICP-MS studies of cadmium and related trace elements in sulfides

The newly discovered Bayanbaolege Ag-Pb-Zn deposit is located in the Southern Great Hinggan Range metallogenic belt, northeastern China, with 1440 t Ag, 380000 t Zn, 50000 t Pb, and a beneficial component of Cd (806 t Cd) and Ga (211 t Ga). The orebodies of this deposit occur as veins and are hosted mainly by a contact zone between the Permian silty slate and the granite intrusion, and have a closely spatio-temporal relationship with the early Cretaceous granodiorite porphyry intrusion.The mineralization process of the Bayanbaolege deposit can be divided into three mineralization stages including arsenopyrite-pyrite-quartz stage (stage I), pyrite-pyrrhotite-chalcopyrite stage (stage II) and galena-sphalerite-argentite -pyrite-calcite stage (stage III). LA-ICP-MS trace element mapping and spot analyses were conducted on the sphalerite and pyrite in stage III at the Bayanbaolege deposit.LA-ICP-MS trace element mapping and spot analyses were conducted on the stage III sphalerite and pyrite selected from the Bayanbaolege deposit in order to identify the occurrence form and distribution characteristics of critical metal elements, constrain the possible controls on the variation of trace elements, reveal the physicochemical condition of mineralization and provide new insights into the ore genesis. The results show that Ga, Ge, In, Cd, Mn, Cu, Ag and Co concentrations in sphalerite, and pyrite is the preferential host for Ge, As and Ni. The occurrence of Ga, Ge, In and Cd in sphalerite are mainly deposited in form of isomorphism. Physicochemical condition studies suggest that sphalerite precipitated from a medium-temperature hydrothermal system with the range from 190 °C to 291 °C (average at 230 °C) and accompanied with the intermediate fS2. Trace element concentrations of sphalerite are different from that of the MVT, VMS, SEDEX and skarn deposits. The results of this study, combined with the previous geological and physicochemical evidence, indicate that the Bayanbaolege Ag-Pb-Zn deposit deposit is an intrusion-related mesothermal hydrothermal vein-type deposit.

Spatiotemporal relationship between hydrocarbon fluid and sandstone‐hosted uranium deposits in the Qianjiadian area, Songliao Basin

The spatiotemporal coupling relationship between deep hydrocarbon fluid and sandstone uranium mineralization within the shallow buried red‐variegated clastic rocks in the Qianjiadian area of the Songliao Basin remains a topic of controversy. This paper aims to provide a comprehensive understanding of the source, nature and exudative age of deep exotic hydrocarbon, as well as the interaction mechanism and alteration process between hydrocarbon fluid and clastic rock. To achieve this, various methods were employed, including acidolysis hydrocarbon test (AHT), clay x‐ray diffraction (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), carbon isotope analysis (CIA) and LA‐ICP‐MS U–Pb isotopic dating. The results indicate that some tight sandstones from the Qingshankou Formation in Dalin uranium deposit exhibit high acidolysis hydrocarbon content (AHC), reaching n × 104 μL/kg, and predominantly consisting of low mature oil‐type gas. Local microscopic observations reveal pore fluorescence and hydrocarbon‐bearing inclusions with nattier blue tone. Furthermore, the kaolinites present in the ore area's sand‐bodies show a significantly higher content anomaly, commonly exceeding &gt;50%, compared to the same layer in peripheral regions. Extensive dissolutions of lithic grains and feldspars are observed, along with the widespread occurrence of ferro‐dolomites and colloidal pyrites. Additionally, exotic asphaltenes are sporadically developed in localized areas. These findings provide evidence that the sand‐bodies experienced a significant exfiltration event of external gaseous fluids. The light carbon isotopes (δ13CV‐PDB ranging from −33.26‰ to −30.06‰) of group components and n‐Alkane suggest that the hydrocarbon originates from the source rock of the Lower Cretaceous Jiufotang Formation. A detailed two‐stage alteration sequence caused by acidic and reducing hydrocarbon is clarified, encompassing acidic corrosion, kaolinization, pyritization, silification and asphaltization during the exudation stage, followed by ferro‐dolomitization in the later cessation stage. Notably, vermicular secondary kaolinites, formed through the interaction between acidic hydrocarbon fluid and low‐temperature meteoric groundwater, serve as significant markers for the exfiltration of deep hydrocarbon fluid. In‐situ U–Pb dating of hydrocarbon‐bearing ferro‐dolomite yielded absolute exfiltration ages of 63.54 ± 4.13 and 65.93 ± 3.35 Ma. By integrating the tectonic–sedimentary–fluid evolution history and uranium mineralization characteristics in the study area, a three‐stage superimposed metallogenic model is proposed for the Upper Cretaceous red‐variegated layers: (1) the sedimentary and diagenetic stage of the target layer during the Late Cretaceous, (2) the predominant hydrocarbon exudation stage at the end of the Late Cretaceous, and (3) the main uranium mineralization stage since the Paleogene. This study enhances our understanding of coupled‐genetic sandstone‐type uranium deposit in a sedimentary basin and provides valuable guidance for prospecting similar red‐variegated beds in the Songliao Basin and other sedimentary basins worldwide.

In-situ molybdenite and rutile geochemistry of the Nannihu porphyry Mo-W deposit, East Qinling, China: A perspective on ore-forming processes

As the important strategic mineral resource, molybdenum is widely utilised by various industries of national economy. Most of the Chinese Mo deposits are classified as porphyry deposits, such as the Nannihu porphyry Mo-W deposit that is one of the biggest Mo deposits in China. Previous studies mostly focused on the geochemistry, geochronology, and isotopic geochemistry of the Nannihu deposit, but its element immigration and occurrence as well as the ore-forming source remain unclear, which limits the development of ore prospecting. Here we document in-situ major and trace element geochemistry of different stages of molybdenite and rutile from the Nannihu deposit, with major aims to determine ore-forming element immigration and occurrence and to reveal ore-forming processes. Based on mineral assemblages and micro-texture, three types of rutile were identified in the Nannihu deposit. The type-1 rutile has stable Y/Ho ratios 16.74–20.82 and similar upper crust rare earth elements (REEs) patterns, which suggest magmatic and crustal origin. The type-2 and 3 rutiles show wide variation Y/Ho ratios (10.69–49.55 for type-2 and 17.85–43.64 for type-3) and belong to hydrothermal rutiles. In addition, two types of molybdenite are also presented, with the Mo1-type for the major ore-forming stage and the Mo2-type for the late ore-forming stage. The fluctuation of elements in the time resolved LA-ICP-MS spectra curve diagram of the Mo1- and Mo2-type molybdenites indicate that the Te, Bi, Pb, Fe and Mn elements are hosted as mineral inclusions in molybdenite lattices. However, the Re and Se elements in these molybdenites display flat signatures and have negative correlations with Mo and S elements, which imply that the Mo and S elements are substituted and occur as isomorphous constituents in molybdenite lattices. The low Re contents (1.60–12.90 ppm) of molybdenites also suggest crustal-mantle mixing metallic sources for the Nannihu deposit. The increasing Fe (4245 to 23943 ppm) and W (1631 to 5922 ppm) contents in hydrothermal type-2 and type-3 rutiles as well as the increasing W contents (113 to 243 ppm) in Mo1- and Mo2-type molybdenites both indicate that the Nannihu ore-forming fluids were under the temperature and oxygen fugacity (fO2) of reduction conditions. The Mo1-type molybdenite is enriched in light REEs and depleted in high field strength elements (HFSEs), and coupled with the late ore-forming stage of F-rich fluorite, which indicate the ore-forming fluid evolution from Cl- to F-rich. Integrating with previous studies, the mineralising fluids of the Nannihu deposit are suggested to be featured by high Cl−, CO2 and metallic contents. The Mo and W ions in mineralising fluids immigrate as Cl-complexes at the early stage of mineralisation, the Mo4+ is then replaced by W4+ in molybdenite lattices at the later stage, and the high temperature and fO2 of the early ore-forming fluids promote the migration of Mo and W elements during ore-forming processes. Eventually, the fluids boiling, and the reduction conditions in temperature and fO2 jointly result in the final precipitation of Mo and W to generate the giant Nannihu deposit under extensional tectonics.

Multistage ore formation in the world’s largest REE-Nb-Fe deposit of Bayan Obo, North China Craton: New insights and implications

The Bayan Obo deposit in the northern margin of the North China Craton is a world-class REE-Nb-Fe deposit, the complex mineralization history of which remains unresolved. In this study, we employ SEM and Image J software combined with mineralogical data obtained by in-situ EDS and EPMA analyses to analyze petrographic images rapidly and to investigate the mineralogical assemblages of each type of rocks/ores from the Main Orebody in an attempt to understand the mineralization process and ore-formation mechanism of this deposit. We identify three metallogenic periods and six ore-forming stages based on the field occurrence of ores combined with published geochronological data. The Mesoproterozoic magmatic event comprises two stages, which were distinguished as the coarse-grained dolomite stage (stage 1) and the fine-grained dolomite stage (stage 2). Three stages were recognized in the Mesoproterozoic shear deformation-hydrothermal mineralization period, including the disseminated mineralization stage (stage 3), the banded mineralization stage (stage 4) and the massive mineralization stage (stage 5). The Paleozoic hydrothermal period involved the vein mineralization stage (stage 6). Based on detailed studies of the mineral assemblages and paragenesis, as well as the complex textures of the ores, we propose a model of the multi-stage metallogenic process as follows: (1) The REE minerals and rutile occurring as inclusions wrapped within magmatic idiomorphic dolomite grains indicate that the REE-Nb mineralization might have started during the magmatic period. (2) The Nb minerals, such as fergusonite and ilmenorutile, intergrown with REE minerals, such as monazite and bastnäsite, indicate that the Nb and REE were transported by the same ore-forming magma or fluid and precipitated during the same metallogenic process. (3) From the fine-grained dolomite stage to the massive mineralization stage (from stage 2 to stage 5), the mineral assemblages become more complex, with a gradual increase in the degree of hydrothermal alteration suggesting that more hydrothermal fluid was involved in the ore mineralization. (4) The complex mineralogical assemblages and textural relationships indicate multiple formation mechanisms for the REE-Nb-Fe minerals. We propose that the unusually large volume of REE-Nb-Fe resources in the Bayan Obo deposit was the result of combined magma and hydrothermal fluid activities in the Mesoproterozoic (from stage 1 to stage 5), whereas the fluids only caused reactivation of the ore materials previously deposited without the addition of exogenous materials in the Paleozoic stage (stage 6).