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The Youjiang metallogenic province (YMP) is a famous ore-concentrating area in South China, known for its substantial Carlin-type gold deposits, antimony deposits, and mercury deposits. Previous studies have yielded conflicting views regarding the ages of mineralization in this area, particularly regarding the occurrence of Yanshanian versus Indosinian ore-forming events during the Mesozoic era. To resolve these discrepancies, this study utilized in situ LA-ICP-MS U-Pb dating on carbonate minerals from the Lannigou Carlin-type Au deposit, the Lanmuchang Hg-(Tl) deposit, and the Sixiangchang Hg deposit to accurately determine their mineralization ages. Our results indicate that the three deposits formed at 137 ± 9 Ma, ~97 Ma, and 454 ± 21 Ma, respectively. By integrating previously reported geochronological data, we propose that the low-temperature Au-As-Sb-Hg-Tl deposits in the YMP were formed during two major periods, Late Triassic and Late Jurassic to Cretaceous, with the latter being more prevalent. Additionally, there was a Paleozoic hydrothermal mercury mineralization event at the northeastern edge of this region. These newly acquired data significantly enhance our understanding of multistage, low-temperature mineralization events in the YMP. Our study also demonstrates that in situ carbonate U-Pb dating is an excellent method for investigating the timing of low-temperature mineralization events. [ABSTRACT FROM AUTHOR]

Zhengminghuaite, ideally Cu6Fe3As4S12, is a new Cu-Fe arsenosulfosalt found in the Zimudang Carlin-type gold deposit in southwestern Guizhou, China. It occurs as irregular, commonly fractured grains of several to a few tens of micrometers in the brecciated gold ores and is paragenetically associated with the late ore-stage mineral assemblage, including realgar, orpiment, pyrite, chalcopyrite, arsenopyrite, aktashite, christite, quartz, and calcite. Zhengminghuaite is opaque with a metallic luster and a conchoidal or uneven fracture. The Vickers microhardness (VHN10) is 219 kg/mm2 (range 192–247 kg/mm2), and the calculated density is 4.77(5) g/cm3. In reflected light, zhengminghuaite is whitish gray with weak bireflectance (whitish gray to pinkish tinted gray), very weak anisotropy, and no internal reflection. Electron microprobe analyses give the empirical formula (Cu5.92Hg0.08)Σ6.00 (Fe1.59Hg1.07Zn0.37)Σ3.03(As3.94Sb0.02)Σ3.96S11.93 on the basis of total cations = 13, with the simplified formula Cu6(Fe,Hg,Zn)3(As,Sb)4S12. Zhengminghuaite is trigonal, with space group R3. Unit-cell parameters determined from the single-crystal X-ray diffraction data are as follows: a = 13.5373(17) Å, c = 9.2354(13) Å, and V = 1465.7(4) Å3 (Z = 3). The eight strongest lines in the X-ray diffraction pattern are [d (Å) (I, %) (hkl)]: 3.0785 (67) (003), 3.0670 (100) (1 3 1), 2.6586 (89) (1 3 2), 1.8825 (97) (134), 1.8773 (82) (520), 1.6060 (89) (13 5), 1.6028 (81) (523), and 1.6012 (83) (26 1). The crystal structure of zhengminghuaite belongs to the nowackiite group and can be described as formed by (0001) layers composed of corner-sharing FeS4 and CuS4 tetrahedra that delimit two triangular cavities. Zhengminghuaite is the Fe-dominant analog at the divalent cations site of nowackiite (Cu6Zn3As4S12) and aktashite (Cu6Hg3As4S12). Paragenetic relationships indicate that zhengminghuaite and associated Hg- and Tl-sulfosalts precipitated in response to the increase in sulfidation state and decrease in temperature of the late-ore stage hydrothermal fluid. [ABSTRACT FROM AUTHOR]

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The Getang is a representative Carlin-type gold deposit in Southwest China. It has a proven reserve of about 30 tonnes at an average grade of 5.1 g/t Au. The orebodies occur as strat-abound lenses, and are structurally controlled by shallow NWW- and NE-trending fold-fault systems and the unconformity between the Upper and Middle Permian. In this study, the regional- and deposit-scale structural investigations, joints and finite strain measurements, and stress and dynamic analysis were conducted with an aim to reveal the structural process of the Getang gold deposit and clarify the relationship between the gold mineralization and structures. Three phases of deformation were identified in the deposit: (1) paleokarst was generated by a crustal uplift when the Youjiang Basin experienced extension at the end of the Middle Permian, laying the foundation for the unconformity; (2) the NW-trending structures were formed under a NNE-SSW compression during the Indochina-South China collision (Indosinian orogeny) in Triassic; (3) the NE-trending structures were generated or reactivated under a NW-SE-oriented compression during the Yanshanian intracontinental orogeny. The unconformity recorded two episodes of tectonic evolution in the NNE-SSW and NW-SE directions. Structural analyses and geochronology data suggest that the Getang gold deposit was formed as a result of tectonic transition from compression to extension during the Yanshanian intracontinental orogeny. [ABSTRACT FROM AUTHOR]

Actively mined Carlin-type gold provinces are only found in Nevada, USA, and SW China. Herein, we combined nanoscale secondary ion mass spectrometry and atom probe tomography to characterize the distribution of Au and As in pyrite from the micrometer to atomic scales from the Shuiyindong and Lannigou deposits, SW China, and compared this with a representative Nevadan deposit. Results show that invisible gold in both deposits occurs in complex micrometer and nanometer scale zones in the rims of pyrite. Within these oscillatory zones, Au is homogenously distributed rather than occurring as nanoclusters. This confirms that invisible gold is principally structure-bound Au, and that ore fluids were not saturated in Au. Gold deposition from undersaturated, arsenic containing, and ore fluids led to the formation of the giant Carlin-type gold deposits. Although not all high-As zones in the Lannigou pyrite contain high Au, all high-Au zones in both deposits contain elevated As. Arsenic is an important criterion for the incorporation of Au, but just because the fluid had high As does not necessarily imply it had/precipitated a high-Au pyrite. Gold atoms, in the Au–As rich zones of pyrite from both deposits, are surrounded by elevated concentrations of As compared to the matrix. Therefore, As both promotes Au incorporation into the pyrite and controls the maximum amount of structure-bound Au in the pyrite. Comparison of the Guizhou pyrite with Nevada pyrite reflects that the pyrite from the two districts exhibits the consistent nanometer- to atomic-scale characteristics. These similar nanometer- to atomic-scale characteristics further support the Guizhou deposits being classed as "Carlin-type." [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Multiple ore bodies are distributed in the Gaolong Dome, and the surrounding circular fractures form the ore bodies. As the research theory of multi-level structural altered body has made significant achievements in gold prospecting in southwest Guizhou, it is believed that the hydrothermal fluid is likely to form a multi-level structural altered body on the unconformity surface near the core of the anticline (dome) or the rock surface with a large variance in dehydratability. Through the first study on the characteristics of the structural altered body in the Gaolong Dome, the characteristics and distribution of the ore body, as well as the circular fractures, were re-recognized. Finally, the potential for ore prospecting was analyzed, which can provide a basis for further prospecting in the Gaolong Dome [ABSTRACT FROM AUTHOR]

The Nanpanjiang basin hosts the world's second-largest concentration of Carlin-type gold deposits. To decipher the origin and evolution of hydrothermal fluid, this study conducted Sm–Nd dating, in-situ trace element, and C-O-Sr isotopic analyses on three types of calcite samples from the giant Lannigou gold deposit in the Nanpanjiang basin, SW China. The type-I calcite, intergrown with Au-bearing arsenian pyrite, has an Sm–Nd isochron age of 213 ± 7 Ma (MSWD = 0.81), indicating that gold mineralization occurred in Late Triassic. The type-II calcite, which coexists with high-maturity bitumens and cut through the main-stage gold orebodies, yields an Sm–Nd age of 188 ± 14 Ma (MSWD = 0.34), representing a post-ore hydrocarbon accumulation event. The type-I and type-II calcite samples have low REE contents (5.28–51.6 ppm) and exhibit MREE-enriched and LREE-/HREE-depleted patterns. Combined with their identical C-O-Sr isotopes, we suggest that hydrothermal fluids responsible for the precipitation of type-I and type-II calcite samples were derived from a mixed metamorphic fluid and meteoric water source. In contrast, the type-III calcite samples, associated with realgar and orpiment, have distinct Mn, Sr, and As contents, REE patterns, and C-O-Sr isotopic composition from the type-I and II calcites, suggestive of different fluid sources. Based on our and previously published data, we propose that the fluid evolution, gold mineralization, and hydrocarbon accumulation in the Nanpanjiang basin are closely related to the Indosinian and Yanshanian orogenies in South China. [ABSTRACT FROM AUTHOR]

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Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To explain the origin of the Carlin-type gold deposit, it is vital to understand their ore-forming chronology. However, the metallogenic age of the deposit remains controversial because of its inadequate traditional dating minerals. Backscattered electron imaging and X-ray elemental mapping of monazite in the Au-rich ore samples obtained from the Laozhaiwan gold deposit in the Golden Triangle region revealed the presence of distinct high-Th cores surrounded by low-Th inclusion-rich rims. The rim of a monazite grain is considered to be formed because of fluid-aided coupled dissolution–reprecipitation via metamorphic reactions during gold mineralization. In this study, hydrothermal monazite formed during the hydrothermal activity of the gold ore was selected as the object of dating, and the metallogenic age of the Carlin-type gold deposit in Laozhaiwan was determined to be 218–230 Ma, indicating Indosinian mineralization. This age was interpreted as the gold mineralization age and correlated with the Re–Os age of arsenopyrite in the Jinya gold deposit, the U–Pb age of rutile, and the 40Ar–39Ar age of sericite in the Zhesang gold deposit. The obtained age data demonstrated that the Indosinian (Triassic) gold mineralization in the Golden Triangle region was related to the progressive closure of the Paleo-Tethys Ocean and the subsequent collision between the South China Craton and Indochina block. The findings show that the metallogenic setting of the Golden Triangle is similar to that of Northeast Vietnam, where mineralization was also related to the closure of the Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

The Central Hunan metallogenic province, located in the southeastern part of the Yangtze Block, South China, is one of the most important Sb–Au metallogenic belts in China. The Baiyunpu gold deposit is one of the important Carlin‐type gold deposits occurring in Devonian sedimentary strata in Central Hunan. Optical microscopy and in situ laser ablation (multi‐collector) inductively coupled plasma mass spectrometry (LA‐[MC]‐ICP‐MS) are used to determine the texture, trace element compositions and sulfur isotope for pyrites from the pre‐ore and syn‐ore stages to constrain the sources of reduced sulfur and metals and the mechanism of gold precipitation. Four generations of pyrite were identified by petrography and pyrite compositions. Pre‐ore Py1 is characterized by relatively low concentrations of As, Au, Sb and Cu and high concentrations of Co, Ni, Bi and Pb. Py1 has positive δ34S values of 6.5–10.1‰, which we ascribe to a bacterial reduction of marine sulfate in closed marine systems, or from weak Rayleigh fractionation by bacterial sulfate reduction (BSR) or thermochemical sulfate reduction (TSR) during sedimentary‐diagenetic processes. Pre‐ore Py2 presents as rims of Py1 and contains relatively high As (69,530 ppm), Sb (123.2 ppm) and low Au (4.89 ppm). Compared with Py2, Py3 has relatively high Au (194.4 ppm) and Cu (24.6 ppm) and low As (40,801 ppm). We interpret that Py2 and Py3 could have precipitated from an Au‐free but As‐rich early hydrothermal fluids or from low‐Au and As‐rich fluids at the beginning of the ore stage. The δ34S values of Py2 and Py3 in the Baiyunpu deposit are concentrated in a narrow range of −1.2 to 1.2‰, suggesting the involvement of magmatic sulfur. Syn‐ore pyrites (Opy) are enriched in Au (517.8 ppm), As (39,719 ppm), Cu (261.9 ppm) and Sb (171.4 ppm). Irregular boundaries between Py1 and Opy suggest that the replacement may have been important for the formation of pyrites at the syn‐ore stage. The variation of As concentration in Opy1, Opy2 and Opy3 appear to have recorded fluctuations in the chemical composition of ore fluids. The δ34S values of Opy (0.1–5.9‰) are slightly higher than Py2 and Py3 due to mixing with sedimentary components with elevated δ34S values in late‐stage hydrothermal fluids. Profile analyses for Baiyunpu auriferous pyrite grains suggest that Au was positively correlated with Cu, but not with As. The correlation between Au, Cu and As in Opy may be dominated by their concentrations of ambient evolving fluids. [ABSTRACT FROM AUTHOR]

Quantitative prediction of mineral resources based on multi-information fusion is the leading topic of resource potential prediction, in which the deep mining of different geological background information and geochemical data is the key problem and still challenging. In this study, we analyzed the spatial distribution characteristics of main metallogenic and associated elements such as Au, Ag, Mn, Cu, Pb, Zn, Sn and Sb in 60767 geochemical samples on the platforms like ArcGIS and GeoDAS, by summerzing the geological background information and metallogenic controlling factors of each tectonic unit in Guangxi. Based on the GeoDAS paltform, through IDW interpolation, S-A anomaly decomposition, principal component analysis and other technologies, the data from the layers with geochemical component element anomaly, gravity and aeromagnetic anomaly and the buffers at the intersection of magmatic rock and fault were used as the training points for the utilization of the fuzzy weights of evidence. A posteriori probability map was drawn up to delineate the favorable metallogenic areas for Carlin-type gold deposit and fracture zone altered gold deposit. This study is of great significance to the application of new metallogenic theories and evaluation techniques in the evaluation or zoning of mineral resources potential.

Copyright of Journal of Geomechanics is the property of Journal of Geomechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The source and evolution of ore-forming fluids is important to understand the genesis of Carlin-type gold deposit. Constraints on the source and evolution of ore fluid components by the conventional geochemical methods have long been a challenge due to the very fine-grained nature and complex textures of hydrothermal minerals in these deposits. In this study, we present the crush-leach analyzed solute data of fluid inclusion extracts within quartz, calcite, realgar, and fluorite from the Shuiyindong, Nibao, and Yata gold deposits in the Youjiang Basin, providing new insights into the source and evolution of ore-forming fluids. The results show that the high molar Cl/Br ratios up to 2 508 in fluid inclusion extracts are indicative of a contribution of magmatic hydrothermal fluids. Fluids mixing between basinal and magmatic-hydrothermal fluids are evident on the plots of Cl/Br versus Na/K ratios, showing that ore-stage milky quartz near the magmatic-hydrothermal fluids reflects magma origin of the ore-forming fluids, whereas late ore-stage drusy quartz and realgar near the defined basinal fluids suggest the later input of basinal fluids in late-ore stage. Although the predominately host rocks in Shuiyindong, Nibao and Yata gold deposit are bioclastic limestone, sedimentary tuff, and calcareous siltstone, respectively, the solute data of fluid inclusion extracts records they underwent the similar fluid-rocks reactions between the Na-rich magmatic hydrothermal fluids and the Ca- and Mg-rich host rocks. This study highlights the solute data of fluid inclusion extracts obtained by crush-leach analyses have the potential to fingerprint the source and evolution of ore-forming fluids of the Carlin-type gold deposit. [ABSTRACT FROM AUTHOR]

Cyanidation has been considered an effective process for extracting gold from gold-bearing ores for over 100 years. However, this process also has several disadvantages including it being toxic, inefficient, and unsuitable for leaching gold from carbonaceous gold ores containing organic and inorganic carbons. Moreover, it is not feasible for the extraction of gold from refractory gold ores , which are increasingly being used.Therefore, there is an urgent need to find an environmentally friendly and efficient leaching method to improve the extraction rate of gold from refractory gold ores. This study discusses using potassium chlorate and bleaching powder for combined leaching of refractory gold ore. Compared with other leaching methods, this method does not require the pre-oxidizing of the refractory gold ore. Moreover, the optimal reaction temperature required for the reaction is lower, thus achieving efficient and environmentally friendly leaching of refractory gold ore. To improve on the method, we used response surface methodology (RSM). RSM can quickly determine the quadratic function connection between the response value and each component and optimize the experimental settings to precisely forecast the experimental findings, saving a significant amount of time and money.This study presents a response surface approach based on a thermodynamic analysis of gold-bearing mineral oxidation to analyze the primary composite design experiment. The response surface model uses four components and three levels of potassium chlorate concentration, bleaching powder addition, reaction temperature, and reaction pH. The model gives 0.16 mol l ^−1 potassium chlorate, 37.5 g bleaching powder, 25 °C reaction temperature, and reaction pH of 13 as the optimal conditions for leaching gold using potassium chlorate and bleaching powder. Under these conditions, the gold leaching rate can reach 90.84%. In addition, the following parameters influence combined gold leaching in decreasing order: bleaching powder dose, reaction temperature, potassium chlorate concentration, and reaction pH.The results show that potassium chlorate and bleaching powder combined is advantageous for leaching of Carlin-type gold ore in Guizhou. It provides a high leaching rate. There is no need for pre-oxidation of gold ore. It is a simple inexpensive process that can be operated at a low optimum reaction temperature. Thus, it is a feasible method in industrial applications and provides a new way for gold leaching.

BACKGROUND: Carlin-type gold deposits have attracted much attention because of the influence of As on the analysis and recovery of gold. It is necessary to develop the specific reference materials (RM) to support application research.OBJECTIVE: Study samples were collected from the super large Carlin-type gold deposit in the Yangshan gold mine, discovered in recent years. Four kinds of reference materials GBW07854-GBW07857 for Carlin-type gold ore were developed according to country-level standard technical specification.METHODS: A total of 20 laboratories simultaneously determined element values. The main gold analysis methods included Atomic Absorption Spectrometry and Fire Assay. Wet analysis uses gradient roasting-activated carbon adsorption of gold to separate arsenic and other interference components. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and Spectrophotometry were mainly used to analyze arsenic. Citation analysis relative deviation permissible limit to define within-group outliers makes up for the incompleteness of the Dixon and Grubbs methods to eliminate outliers.RESULTS: The homogeneity test index F < F0.05(29, 30)=1.84, indicated that there were no significant differences between the groups and within the group. No statistically significant changes were observed in 5 analyses during 22 months. The certified values of gold and arsenic in this series of certified reference materials (CRMs) were superior to those of the same level country-level gold ore RM and foreign arsenic-bearing polymetallic ore RM.CONCLUSIONS: This series of CRMs can be used as standards for the analysis and study of gold and arsenic in Carlin-type gold deposits.

Copyright of Acta Geoscientica Sinica is the property of Acta Geoscientica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study examines the whole-rock geochemistry, Fe-oxide texture and crystal morphology, and Fe-oxide (U-Th)/He date variation of jasperoids, as well as the relationships between these characteristics, in order to evaluate jasperoids as an indicator for gold mineralization. Jasperoid samples with a range of textures, appearances, and expected gold concentrations were collected from two gold districts in Nevada: the northern Carlin trend (Gold Quarry Mine), and the Battle Mountain district (Marigold Mine; Battle Mountain prospect). In our jasperoid samples, whole-rock concentrations of Au are positively correlated with As, Ag, Pb, Sb, U, W, and Tl. The following Fe-oxide textures are associated with anomalous gold concentrations: disseminated, submicron crystals; feathery and acicular crystal morphologies; concentric zonation from hematite to goethite; and botryoidal textures. Calculated closure temperatures for the (U-Th)/He system in observed jasperoid Fe-oxide morphologies within our dataset range from 26 to 136 °C, indicating variable susceptibility to He diffusion at near-surface conditions. Fe-oxide (U-Th)/He dates range from 29.4 ± 0.5 Ma to 0.11 ± 0.01 Ma, displaying intra- and intersample variation. We attribute the date variation to multiple factors including He implantation, parent isotope exchange, and He loss through closure temperature sensitivity and alpha-ejection. The intra- and intersample variation within the Fe-oxide (U-Th)/He dates limits our ability to make geologic interpretations. Our case study identifies important limitations of the (U-Th)/He method in jasperoids and provides insight on how He date variation might be avoided in future studies. [ABSTRACT FROM AUTHOR]

The metallogenic model of isolated carbonate platform in western Guangxi. [Display omitted] • The gold deposits discovered within the isolated carbonate platform in western Guangxi, China are Carlin-type gold deposits. • In-situ LA-ICP-MS Rb-Sr dating on illite indicates that Carlin-type gold deposits inside and around the isolated carbonate platform are products of the same mineralization system, influenced by post-Indosinian extensional events. • The Cambrian represents a new exploration horizon, while the interior of the isolated carbonate platform emerges as a fresh prospecting area in western Guangxi. The western Guangxi is a crucial component of the Guizhou–Yunnan–Guangxi "Golden Triangle"(hereafter referred to as the Golden Triangle) of South China. The most discovered Carlin-type gold deposits in this region are primarily situated at the periphery of isolated carbonate platforms. The ore bodies are vein-like in form controlled by faults, and the wall rock are Triassic carbonate-bearing terrigenous clastic rocks. Recently, some gold deposits have been discovered in the interior of isolated carbonate platforms. The ore bodies are primarily stratiform hosted in sedimentary unconformities. The mineralized strata span from the Cambrian to the Permian, and the host rock include sandy and muddy dolostones, as well as a combination of sandstone, mudstone, tuff, and chert. The geological and geochemical characteristics suggest that these stratiform deposits in the interior of isolated carbonate platforms share common characteristic with Carlin-type gold deposits in China and USA. However, it remains uncertain whether these deposits are products of the one mineralization system and are coeval with those vein deposits at the periphery of the isolated platforms. To address this question, we conducted geological and isotopic dating studies on the Longhuo gold deposit and the De'e gold occurrence in the interior of isolated platforms. The Longhuo stratiform gold deposit occurs along a parallel unconformity in the Carboniferous/Devonian composed of sandstone, shale, tuff, and chert. Hydrothermal illite, quartz and auriferous pyrite fill along joints and fissures, implying that illite formed during the main ore-forming stage and its age could represent the age of gold mineralization. The stratiform orebodies of De'e gold occurrence are hosted in Cambrian sandy and muddy dolostones. Gold occurs as invisible Au in zoned pyrite and arsenopyrite, with a dominant alteration assemblage of silicification, carbonate alteration, and illitization. Hydrothermal quartz, illite and dolomite often aggregate with zoned auriferous pyrite and arsenopyrite in the most intensely altered zones, suggesting that illite formed during the main ore-forming stage and its age could also represent the age of gold mineralization. Illite LA-ICP-MS Rb-Sr dating was performed on both deposits, yielding ages of 184.16 ± 3.14 Ma for the Longhuo gold deposit and 191.21 ± 6.76 Ma for the De'e gold occurrence. Previous studies have indicated that Carlin-type gold deposits in the Golden Triangle exhibits two distinct age clusters, one ranging from 184 to 235 Ma and the other from 134 to 148.4 Ma. These dual age clusters suggest the potential occurrence of two mineralization events. The obtained ∼ 190 Ma mineralization ages for the Longhuo and De'e gold deposits in this study indicate that the Carlin-type gold mineralization within the isolated platform took place during the Early Jurassic. This aligns with the early mineralization event of gold deposits along the platform's edge, implying that gold deposits inside and around the isolated carbonate platform are products of the same mineralization system, influenced by post-Indosinian extensional events. The interior of the isolated carbonate platform holds substantial exploration potential, making it a novel direction for prospecting Carlin-type gold deposits in western Guangxi. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deep hidden gold orebodies in the Dian–Qian–Gui Golden Triangle have weak soil geochemical anomalies. • We analyzed the effectiveness and practicality of tectono-geochemistry method for weak information extraction in the area. • Tectono-geochemical data contain more significant anomalies than soil geochemical data. • Tectono-geochemical extraction reveals anomalies related to deep-seated orebodies. • We used tectono-geochemistry method to identify several future targets of deep-mineral exploration. Following decades of exploration of Carlin-type gold deposits in the Yunnan, Guizhou, and Guangxi provinces of China (known as the Dian–Qian–Gui Golden Triangle), surface mines are almost exhausted and undiscovered gold orebodies are deeply buried; thus, surficial geochemical information associated with concealed gold orebodies is poor. In this study, we compared methods of extracting this weak information based on soil geochemistry and tectono-geochemistry, and then applied the tectono-geochemical method to the Huijiabao and Nibao gold ore fields to evaluate its validity and identify favorable prospecting targets for deep-mineral exploration. We analyzed 8,842 soil geochemical samples and 4,049 tectono-geochemical samples from the Nibao gold ore field and its surroundings, and 253 tectono-geochemical samples from the Huijiabao gold ore field by statistical analysis and geochemical mapping. Tectono-geochemical samples were less abundant, accounting for only approximately 60 % of the number of soil geochemical samples; however, the number and proportion of high-value samples were greater and the elemental content was typically higher. Primary geochemical information related to deep-seated Carlin-type gold orebodies is profoundly affected by structures such as faults, anticlines, joints, and fissures, and was effectively identified by the tectono-geochemical technique, which focuses on tectonic and altered rocks. Conversely, soil geochemical information derived from these primary sources was significantly weaker because of the high mixing and homogeneity of elements during weathering. Eleven tectono-geochemical high composite anomalies of Au, Hg, Sb, As, and W were recognized in the east of the Nibao ore field, with Baogudi, Shuijingwan, Jiaozishan, Houzipo, Anzhe, and Hetaoshu predicted to be future targets of deep-mineral exploration. The Nayang–Yandengpo target was delineated according to high tectono-geochemical composite anomalies of Au, Hg, Sb, As, and Tl in the southeast part of the Huijiabao ore field, and nine concealed gold orebodies were identified at depths of 800–1,400 m through 37 boreholes, with a total gold resource of 16,338 kg and an average grade of 3.74 g/t. Successful case studies and applications demonstrate the effectiveness of tectono-geochemical information extraction method for detecting subtle signals from concealed orebodies, which will promote future deep exploration of the Dian–Qian–Gui Golden Triangle. [ABSTRACT FROM AUTHOR]

The Jiadi gold deposit is a newly discovered Carlin‐type gold deposit in the Guizhou Province, Southwest China. This deposit is structurally controlled by a shallow fold–fault superimposed system along the Lianhuashan trend. Field geological investigations, structural analysis, and mathematical research are conducted to study its structures and hydrothermal fluid flow process. Geological investigations (i.e. sections, stope, and drill hole) indicate that the structures are dominated by NE‐trending folds, NWW‐trending folds, and faults. A trend‐surface analysis of the low interformational fracture zone suggests that the overall distribution of the Lianhuashan trend is controlled by the NE‐trending Lianhuashan anticline. Nearly all primary Carlin‐type gold deposits are distributed along the southeastern flank where the fold axis changes from NE to EW. Gold orebodies are hosted by the interformational fracture zones and primarily situated at the transitions from the high‐value areas to the low‐value areas of the interformational fracture zones. A stress analysis on the hydrothermal veins indicates that they are of tenso‐shear properties. The ore‐forming elements (Au, As, Sb, Hg, and Tl) of the hydrothermal veins from the interformational fracture zones and intrusive breccia body present strong positive anomalies compared with those from the adjacent wall rocks. According to the development patterns of the ore‐forming elements and hydrothermal veins, a migration process of the ore‐forming fluids is proposed: the deeply sourced ore‐forming fluids migrated vertically to shallow crust along an intrusive breccia body, subsequently flowed horizontally along the interformational fracture zones accompanied by gold precipitation in the early stage, and finally migrated outward along steep micro‐fractures during following stages. Gold distribution regularities controlled by structures in the Jiadi Carlin‐type gold deposit are analyzed using geological investigations, structural analyses, and mathematical research. According to the development patterns of the ore‐forming elements and hydrothermal veins, a migration process of the ore‐forming fluids is proposed. [ABSTRACT FROM AUTHOR]

The Dashui gold deposit occurs in the south of West Qinling orogenic belt where is belonged to a famous gold triangle area named “Shan‐Gan‐Chuan” in Northwest China. The presence of native Au associated with hematite alteration is unique in China. The ore bodies at Dashui mainly occur in the limestone and dolomitic limestone units within the Lower Triassic Maresongduo Formation. The granodioritic dykes that intrude the Triassic sedimentary rocks are locally mineralized because of later carbonate alteration. The ore bodies are vein, lenticular, cystic, and dendritic in shape and are controlled by NW‐, NNE‐ (near N‐S‐), and E‐W‐trending faults. Gold mineralization occurs commonly at fault intersections and contact zones between the carbonate and magmatic rocks. The NNE‐ (near N‐S‐) trending faults and associated pinnate fractures are most favorable loci for gold deposition. The metallic minerals include native Au, pyrite, cinnabar, and marcasite, which are mostly overprinted by an oxidized mineral assemblage of hematite and limonite. Gold mineralization is closely associated with decalcification, silicification, and carbonate alterations. Gold content in altered samples correlates with Si enrichment and Ca and Mg depletions. Rare earth elements (REE) increase with Al2O3 and Fe2O3 in altered carbonate rocks, indicating that an enrichment of REE may be closely related to argillic alteration and supergene weathering. The REE patterns of altered carbonate rocks are more likely consistent with granodiorite instead of the ones of fresh carbonate rocks. Moreover, δ34S values of Dashui deposit ranging from −1.8‰ to 4.1‰ indicate that the deep‐sourced magmatic hydrothermal fluids may have worked during the early stage mineralization. Altered carbonate rocks show higher δ13C and lower δ18O values than those of the original host rock. Therefore, the REE, S, C, and O data suggest that the ore‐forming fluids may be magmatic derived and later interact and exchange with host rock and meteoric water. The Dashui gold deposit is characterized by structural and stratigraphic controls; Au–As–Sb–Hg geochemical association; alteration of decalcification, silicification, and argillization; low base‐metals; high Au/Ag ratio; and low δ18O values. These features are consistent with Carlin‐type Au deposits in Western USA, suggesting that the Dashui deposit is a Carlin‐type deposit that formed in the Middle Jurassic to Early Cretaceous (170 to 135 Ma). [ABSTRACT FROM AUTHOR]

[Display omitted] • A fractal dimension calculation program based on the Matlab platform was developed to perform a fractal analysis of the gold concentration values (g/t). • Fractal dimension can be used to better constrain possible ore-bearing fluid flow paths. • Realized the quantitative description of the spatial variation characteristics of ore-forming elements. • The fractal dimension gradient plays a significant role as a spatial proxy to locate the potential economic gold deposits. • The mechanisms of dispersion and aggregation as well as the spatial and temporal distribution patterns of mineralised elements during the formation and evolution of the mineralised system are revealed. The spatial distribution of ore-forming element grades typically exhibits strong nonlinear characteristics as a result of continuous geological processes. The trend of change in ore grade sequences is a crucial indicator of the degree of enrichment of an ore deposit. Therefore, quantitative evaluation of the spatial distribution of ore-forming elements holds great significance for understanding ore-forming processes as well as for ore exploration. In this work, based on the principles of fractal theory, a MATLAB-based program to calculate fractal dimensions was developed, and fractal analysis was conducted on the gold concentration values (g/t) of 25 drill holes in the Lannigou Gold Mining Area, Guizhou, China. Rescaled range analysis and the fractal correlation integral were utilized to obtain the spatial distribution of gold concentrations in the drill holes. Rescaled range analysis revealed that the Hurst exponent (H R/S) values vary in the range of 0.58–0.97, which reflected the persistent behavior of vertical variation in gold tonnage at the studied wells. Furthermore, the relationship between gold grade distribution and associated fluctuations in the fractal dimension derived from the correlation dimension (D C) was discussed. The D C value was found to vary between 1.01 and 1.59, indicating that high-grade gold deposits were distributed along steep fractal gradients and that fractal dimension values could be used as a reliable proxy to efficiently understand the migration pathways of auriferous fluid. Studies have shown that the Hurst exponent of the Au grade sequence exhibited a strong dependence on the grade of mineralization, with gold mineralized veins persisting throughout the studied drill holes. Thus, fractal dimension gradients can serve as an important proxy for identifying the locations of potential economic gold deposits in unexplored areas. Moreover, this approach can be employed to map the distribution patterns of other types of ore deposits. [ABSTRACT FROM AUTHOR]

The contiguous region between Guangxi, Guizhou, and Yunnan, commonly referred to as the Golden Triangle region in SW China, hosts many Carlin-type gold deposits. Previously, the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating. This paper reports the first SIMS U-Pb age of hydrothermal rutile crystals for the Zhesang Carlin-type gold deposit in the region. The hydrothermal U-bearing rutile associated with gold-bearing sulfides in the deposit yields an U-Pb age of 213.6 ± 5.4 Ma, which is within the range of the previously reported arsenopyrite Re-Os isochron ages (204 ± 19 to 235 ± 33 Ma) for three other Carlin-type gold deposits in the region. Our new and more precise rutile U-Pb age confirms that the gold mineralization was contemporaneous with the Triassic W-Sn mineralization and associated granitic magmatism in the surrounding regions. Based on the temporal correlation, we postulate that coeval granitic plutons may be present at greater depths in the Golden Triangle region and that the formation of the Carlin-type gold deposits is probably linked to the coeval granitic magmatism in the region. This study clearly demonstrates that in situ rutile U-Pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile. [ABSTRACT FROM AUTHOR]

The Shuiyindong gold deposit is a deeply concealed strata-bound Carlin-type deposit in southwestern Guizhou Province, China. The deposit lies on the eastern limb of the Huijiabao anticline with ores mainly along the anticline axis and hosted in bioclastic limestone, containing calcite veins, of the Permian Longtan Formation units. In this study, we measured carbon and oxygen isotopic ratios and rare earth element (REE) concentrations of the host rocks and calcite veins along a profile across the Shuiyindong deposit. Orebodies in the upper unit of the Longtan Formation have higher δ 18 O values (20.6–22.4‰) and lower δ 13 C values (−3.7 to −0.5‰) than the country rocks (δ 18 O: 18.8–21.4‰; δ 13 C: −0.7 to 0.8‰). However, there are no obvious trends of δ 18 O and δ 13 C values from the country rocks to the orebodies in the middle unit of the Longtan Formation. The spatial distribution of the calcite veins displays distinct halos of δ 13 C and δ 18 O values and REE concentrations. Calcite veins along the anticlinal axis and major reverse fault are enriched in Middle REE (Sm, Eu, Gd, and Tb) and 18 O and depleted in 13 C. Surficial veining calcite-filled fractures/faults that connect to deep concealed strata-bound gold mineralization systems can be vectors toward deep ores in southwestern Guizhou Province, China. [ABSTRACT FROM AUTHOR]

[Display omitted] • A close spatial contact and a temporal order were recognized between the porphyry dykes and gold orebodies at Mingshan, Youjiang Carlin-type goldfield, SW China. • Fluid inclusion microthermometry and H-O isotopes of ore stage hydrothermal veins suggest a metamorphic origin for the ore-forming fluid. • Genetic link between the magmatism and Carlin-type gold mineralization is not supported at Mingshan. • The Early Cretaceous Carlin-type gold mineralization in SW China is associated with the post-orogenic extension in a NW-SE extensional regime which triggered by the slab window opening during the rollback of the subducted Pacific slab. The Youjiang Basin in Southwest (SW) China is the second-largest Carlin-type goldfield in the world after Nevada, USA; however, the spatial, temporal, and genetic links between Carlin-type Au mineralization and magmatism in SW China remain controversial compared with those in Nevada. The Mingshan gold deposit is one of the few Carlin-type gold deposits that exhibits a close spatial relationship between gold orebodies and magmatic rocks in the Youjiang Basin. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) uranium-lead (U-Pb) dating of magmatic zircons from quartz porphyry dikes and hydrothermal apatite associated with gold yields the intrusive and gold mineralization ages of 96.34 ± 0.89 and 139.9 ± 4.8 Ma, respectively, indicating that the magmatism was much younger than the gold mineralization at Mingshan. Petrography and microthermometry of the fluid inclusions from ore-stage quartz and calcite suggest a low to moderate temperature (140–240 °C), low salinity (3–8 wt% NaCl eqv), and moderate to low density fluid. The hydrogen and oxygen isotope compositions of the ore-stage quartz indicate a metamorphic fluid source of the ore fluid. Thus, we propose that the close spatial contact between the gold orebodies and igneous dikes could have resulted from the same NWW-trending fault space during the Early Cretaceous precipitation of ore fluid and the Late Cretaceous intrusion of the quartz porphyry dikes. However, the genetic link between the quartz porphyry and Carlin-type Au mineralization was not observed at Mingshan. The primary metamorphic fluid associated with Early Cretaceous gold mineralization in the Youjiang Basin was derived from syn -orogenic shortening deformation and metamorphism in the compressional tectonic setting caused by the subduction of the Paleo-Pacific Plate. Subsequent post-orogenic extension during the rollback of the subducted Pacific slab led to significant extensional faults and intrusions of Early Cretaceous concealed granites, which may have provided heat, materials, and energy for the transport of ore fluid. The ore fluid was transported through permeable extensional structures from the deep crust and reacted with the carbonaceous and Fe-rich host rocks in the shallow crust, resulting in the Early Cretaceous gold mineralization event in the Youjiang Basin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both oil and gas may involve the mineralization of the Carlin-type gold deposit. • Pyrobitumen EPMA and TEM analysis indicate oil may act as gold carrier. • Pyrite EPMA and S isotope data suggest gas dominated TSR provide the sulfur. The spatial association of hydrocarbons with metalliferous ore deposits, like MVT lead–zinc deposits, sandstone uranium deposits and various type gold deposits (epithermal Au-Ag (-Hg) deposits, orogenic gold deposits and Carlin-type gold deposits) is found worldwide. However, the genetic relationship between hydrocarbon evolution and mineralization is still under controversy. Integrating isotope dates related to timing of petroleum evolution and gold mineralization from published data, as well as high-resolution transmission electron microscopy (TEM) analysis of pyrobitumen, electron probe microanalysis (EPMA) on both pyrobitumen and pyrite, the In-situ S isotope analyses of the gold-bearing pyrite in this study, we consider different type hydrocarbons (liquid oil and gas) played different roles on the mineralization of Carlin type gold deposits. As the residue of liquid oil cracking, the widespread high maturity pyrobitumen within the reservoir indicate both oil and gas has ever accumulated in the Nanpanjiang Basin. The high gold abundance (EPMA: ∼120 ppm; TEM: ∼1500 ppm) within the pyrobitumen in agreement with the metal solubility experiment suggest liquid oils could have acted as gold carrier before metal precipitation. The late Triassic timing overlapping between gas generation and gold mineralization and the δ34S features with gold bearing pyrite ∼ 10 ‰ lighter than the coeval seawater sulfate indicate gas dominated TSR process may play an important role on the supply of gold bisulfide complex (Au(HS) 2 −) in the ore-forming fluid and directly involved the precipitation of the Carlin-type gold deposit. [ABSTRACT FROM AUTHOR]

Shuiyindong is one of the largest and highest grade stratabound Carlin-type gold deposits in China. This paper reports on the results of petrographic studies, electron microprobe analyses (EMPA) of arsenian pyrite, and the mass transfer during mineralization and alteration, and it presents the deposit-scale distributions of Au, As, Sb, Hg, Tl, and trace elements in a representative cross section across the Shuiyindong Carlin-type gold deposit, Guizhou Province. The main objectives were to identify the precipitation mechanisms of minerals, or elements from fluids, and the migration paths of ore-forming fluids. Petrographic and EMPA studies indicate that gold in the primary ores is mainly hosted by arsenian pyrite. Mass transfer associated with alteration and mineralization shows that Au, As, Sb, Hg, Tl, and S were significantly added to all mineralized rocks, Fe 2 O 3 and SiO 2 were immobile in the main orebodies that are hosted in bioclastic limestone, and CaO, Na 2 O, Sr, and Li were removed from country rocks. The relations between Fe and S indicate that the sedimentary rocks at the Shuiyindong deposit contain more iron than is needed to combine with all of their contained sulfur to form pyrite. This suggests that sulfidation and decarbonation were the principal mechanism of gold precipitation at the Shuiyindong deposit. Hg, Sb, and As commonly formed sulfide minerals, such as stibnite, realgar, and orpiment, in late-stage quartz–calcite veins, or absorbed by organic matter in argillite. Fluid cooling presumably led to depositions of stibnite, realgar, and orpiment in late-stage quartz–calcite veins. Organic matter likely served as a reductant in argillite for the ore fluids, causing the precipitation of As, Sb, Hg, and S, as well as Au. Deposit-scale distributions of gold and other relevant elements reflect the passage of fluids through the rocks. Rock strata and structures allowed the ore-forming fluids to migrate horizontally along the unconformity surface of the Middle–Upper Permian, converge on the high position of an anticline, and then ascend into the overlying strata along the anticlinal axis. The distributions of the major and trace elements show that elements that accompanied the ore-forming fluids include Au, As, Sb, Hg, Tl, and S, and that Na 2 O and Li were exhausted in the Longtan Formation at the anticlinal core during gold mineralization. The enrichment of Co, Cr, and Ni in the Longtan Formation at the anticlinal core might be associated with deformation that formed the anticline, or with gold mineralization. Different host rocks were preferentially mineralized by different elements. The bioclastic limestone is commonly enriched in Au, whereas the argillite is preferentially enriched in As, Hg, Sb, and Tl. The zonation of ore-forming elements in the deposit appears to be Sb–Tl–As–Hg–Au–Hg–As (from bottom to top). Enrichment of Au, As, Sb, Hg, and Tl provides useful guidance for the exploration for Carlin-type gold deposits in Guizhou. Anomalies of As and Hg in soil or stream sediment might be an important clue and these elements can be used as indicator elements. Ore-forming fluids migrated along the unconformity surface of the Middle–Upper Permian and the anticlinal axis, so these are favorable sites for exploration for Carlin-type gold deposits in Guizhou. [ABSTRACT FROM AUTHOR]

The Yunnan–Guizhou–Guangxi “golden triangle” is considered as one of the important regions for Carlin-type (or Carlin-like) gold deposits in China. Gold deposits in this region can be grouped into lode type controlled by faults and layer-like type controlled by host strata. Arsenopyrite is one of the major gold-bearing minerals in these deposits. Here we report the S and Pb isotopic composition of arsenopyrites from the fault-controlled Lannigou and Jinya gold deposits and the stratabound Shuiyindong gold deposits, with a view to trace the sources of sulfur and lead, and to evaluate the genetic aspects of gold mineralization. The average δ 34 S values of arsenopyrites are 11.7‰ for Lannigou, 6.7‰ for Shuiyindong and −5.3‰ for Jinya, which are slightly lower to that of diagenetic pyrite in the host rocks of each deposit. The δ 34 S values of arsenopyrites show significant variation among the different deposits (−9.0‰ to +17.1‰), which indicate a sedimentary origin for sulfur, followed by local fluid–rock interaction. The Pb isotopic composition of arsenopyrites from these deposits shows a narrow range ( 206 Pb/ 204 Pb = 18.494–18.813, 207 Pb/ 204 Pb = 15.630–15.748, 208 Pb/ 204 Pb = 38.559–38.884), indicating that the different deposits have the same source of lead. Based on a comparison with Pb isotopic ratios of diagenetic pyrite, arsenopyrite and Late Cretaceous magmatic rocks from this region reported in previous studies, we infer that the lead was sourced from the sediments rather than from magmatic intrusions. The formation of the Carlin-type gold deposits are therefore correlated with the evolution of the Youjiang basin from rifting to closure, and involved four distinct stages leading to the concentration of the gold ores. [ABSTRACT FROM AUTHOR]

The Zimudang gold deposit is a large Carlin-type gold deposit in the Southwest Guizhou Province, China, with an average Au content of 6.2 g/t. Gold is mainly hosted in the fault zone and surrounding strata of the F1 fault and Permian Longtan Formation, and the ore bodies are strictly controlled by both the faults and strata. Detailed mineralogy and geochemistry studies are conducted to help judge the nature of ore-forming fluids. The results indicate that the Au is generally rich in the sulfides of both ores and wall rocks in the deposit, and the arsenian pyrite and arsenopyrite are the main gold-bearing sulfides. Four subtypes of arsenian pyrite are found in the deposit, including the euhedral and subhedral pyrite, framboidal pyrite, pyrite aggregates and pyrite veins. The euhedral and subhedral pyrite, which can take up about 80% of total pyrite grains, is the dominant type. Au distributed unevenly in the euhedral and subhedral pyrite, and the content of the Au in the rim is relatively higher than in the core. Au in the pyrite veins and pyrite aggregates is lower than the euhedral and subhedral pyrite. No Au has been detected in the points of framboidal pyrites in this study. An obvious highly enriched As rim exists in the X-ray images of euhedral pyrites, implying the ore-forming fluids may be rich in As. The relationship between Au and As reveals that the Au may host as a solid solution ( Au+) and nanoparticles of native gold ( Au0) in the sulfides. The high Co/ Ni ratio (>1) of sulfides and the enrichment of W in the ores all reflect that the gold-bearing minerals and ore-forming process were mainly related to the hydrothermal fluids, but the magmatic and volcanic activities cannot be neglected. The general existence of Au and As in the sulfides of both ores and wall rocks and the REE results suggest that the ore-forming fluids may mainly be derived from the basin itself. The enrichment of Tl suggests that the ore-forming fluids may be enriched in Cl. The Ce and Eu show slightly or apparently negative anomalies, which means the ore fluids were probably formed under reducing environment. The Y/ Ho ratios of ore samples fluctuate around 28, implying the bicarbonate complexation and fluorine were both involved in the ore-forming process. Combined with the previous studies and our results, we infer that the ore-forming fluids enriched Au, As, HS− and halogen ( F, Cl) were derived from the mixture of reducing basinal fluids and magmatic or volcanic hydrothermal fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • The source of metals is key to discriminating orogenic and Carlin gold deposits. • The majority of gold in Jiagantan is structurally bound in Py1 and Apy1. • The ore-forming materials were derived by metamorphism of Devonian strata. • Jiagantan is classified as an epizonal orogenic gold deposit. Sediment-hosted disseminated gold deposits in orogenic belts share many similarities to both epizonal orogenic and Carlin-type gold deposits, leading to a lot of difficulties in their genetic classification. The giant Jiagantan gold deposit was newly discovered in the West Qinling orogen, central China, and was selected to provide a better understanding of this issue. Gold mineralization at Jiagantan is hosted within sandstone and silty slate, and the gold is intimately associated to disseminated pyrite and arsenopyrite. Three generations of pyrite (Py0, Py1, and Py2) and two generations of arsenopyrite (Apy1 and Apy2) are recognized and used to perform in situ textural, chemical, and sulfur isotopic analyses. The diagenetic Py0 is framboidal and porous, and contains elevated concentrations of As, Sb, Co, Ni, Cu, Ti, and V. The early mineralization stage Py1 and Apy1 are disseminated within sandstone and silty slate, and have the highest average Au concentrations of 7.7 ppm and 12.6 ppm, respectively. The intermediate mineralization stage Py2 and Apy2 are hosted by quartz veins and veinlets, coexisting with stibnite, chalcopyrite, and minor amounts of other sulfides. Gold mineralization mainly took place during the early mineralization stage. Microscopic observations and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) output graphs confirm the majority of gold may reside in the crystallographic structures of Py1 and Apy1. The diagenetic Py0 grains show negative δ34S values of −25.2 to −20.1‰, implying the derivation of sulfur by bacterial reduction of marine sulfate. The hydrothermal Py1, Py2, Apy1, and Apy2 have higher but still negative δ34S values ranging from −16.4 to −5.0‰, suggesting an origin of sulfur from metamorphism of the underlying Devonian sedimentary rocks. The Jiagantan gold deposit can best be classified as an epizonal orogenic gold deposit owing to the possible metamorphic origin of Au, As, S, and other associated elements. The source of ore-forming materials is the key to discriminating orogenic gold deposits from Carlin-type gold deposits, while the type of host rocks, the style of mineralization, and the occurrence state of gold may not be the effective indicators. [ABSTRACT FROM AUTHOR]

The Jinlongshan gold deposit, Shaanxi Province, is a large Carlin-type deposit in the Western Qinling Gold Province (WQGP) in the Qinling Orogenic Belt, Central China. In this study, we present new EPMA and LA-ICP-MS geochemical data on the Fe-S-As minerals at Jinlongshan, which consist mainly of pyrite, arsenian pyrite and arsenopyrite. Diagenetic pyrite (Py0) is preferentially hosted in the sedimentary rocks as rounded or framboidal aggregates. Three types of hydrothermal pyrite (Py1, Py2 and Py3) and two types of arsenopyrite (Apy1 and Apy2) were newly identified in the ores and wall-rocks: fine-grained Py1 and Apy1 were formed at the early mineralization stage; coarse-grained Py2 and Apy2 were formed at the middle mineralization stage; and Py3 with stibnite were formed at the late mineralization stage. Their trace elements differ in concentrations, associations and rim-core zonations, implying different genesis and crystallization processes. Py0 is As-poor (Au < 0.105 wt% and As < 0.094 wt%); Py1 and Py2 are Au-As-rich (Au = 1.9-113 ppm and As up to 7.270 wt%); Py3 is Au-As-poor (Au = 0.03-11.4 ppm and As < 0.56 wt%); and Apy1 and Apy2 show the highest Au concentration (up to 576 ppm). Co, Ni and As (±Se and Te) occur in pyrite as isomorphism, and Ag, Cu, Pb and Zn are distributed primarily as invisible or visible sulphide inclusions. The dominant state of Au in the hydrothermal Fe-S-As minerals at Jinlongshan is lattice bound Au+1, and possibly invisible Au0 nanoparticles, whereas in the diagenetic Py0, the dominant state is mainly Au0. By integrating the evidence from ore deposit geology, mineral morphology, internal structure and trace element geochemistry of the Au-bearing Fe-S-As minerals, it is concluded that the formation of the Jinlongshan Au deposit may have been related to the regional metallogenic episode at around 170 Ma in the WQGP, which was coeval with the regional tectonic transition from a collisional compression to a late- to post-collisional extension in the Qinling Orogen. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Mining activities change the groundwater level and flow conditions through pumping and drainage, which enhances the interaction between groundwater and aquifer rocks; mine drainage is discharged into the surface water system, which affects the whole karst water hydrogeochemical process. Based on hydrogeochemistry and the δ 34 S isotope, the hydrogeochemical processes, characteristics, and main controlling factors for waste water, karst groundwater, and surface water in a typical Carlin gold mining area and its surrounding areas were revealed. The results showed that:chemical compositions of groundwater and surface water unaffected by gold mining activities were mainly controlled by the weathering of limestone and dolomitic limestone; Ca 2+ , Mg 2+ , and HCO 3 - were main ions; and the water chemical types were Ca-HCO 3 . The mine wastewater and its downstream receiving water were affected by the dissolution of carbonate and silicate minerals, and cation exchange also played a role; the main ions were Ca 2+ , Mg 2+ , Na + , and SO 4 2- , and the hydrochemical type gradually evolved from Ca-HCO 3 to Ca-SO 4 . SO 4 2- was the characteristic component in various water bodies affected by mining, and the concentration of SO 4 2- gradually decreased from top to bottom in the well. The values of δ 34 S for unaffected groundwater and surface water were positive, and SO 4 2- was mainly derived from realgar oxidation. Conversely, mine wastewater and downstream water were negative, SO 4 2- was mainly influenced by the mixing action of realgar oxidation and meteoric precipitation, and pyrite also contributed to a certain extent. At the same time, NO 3 - came from agricultural fertilizer and rural domestic sewage discharge directly. Principal component analysis (PCA) further demonstrated:sulfide mineral oxidation and mining activities were the main controlling factors for the water chemical composition of mine wastewater and downstream water, whereas unaffected groundwater and surface water were mainly influenced by water-rock (carbonate rock) interactions. Agricultural fertilizer and rural sewage discharge also had a certain influence. Therefore, the study area should strengthen the interception of surface water, control-block-management of sulfide oxidation, rural domestic sewage treatment, and agricultural fertilizer.

The 87Sr/86Sr values for main-ore stage apatite (Ap2) and late-ore stage apatite (Ap3) at Badu, showing that the data plot between the Lower Cambrian basement rocks in the Youjiang basin. [Display omitted] • Hydrothermal apatite is chemically (e.g., Cl, Mn) different from magmatic one at Badu. • Ore-forming fluids are mainly basement-sourced with deep magmatic input. • Basement input critical for Carlin-type Au mineralization in Youjiang basin. The Paleozoic-Mesozoic Youjiang sedimentary basin in SW China is developed on a Lower Paleozoic low-grade metamorphic basement, and contains dozens of Carlin-type gold deposits with a total Au reserve of over 900 metric tonnes (t). Although most of these deposits are hosted in sedimentary rocks, ∼70% of the gold (∼24.5 t) in the Badu deposit is hosted in altered OIB-type dolerite. To date, the ore-fluid source of Carlin-type gold deposits in the basin is highly debated, hampering the formulation of genetic models. Here, for the first time, we present ore-related apatite chemical and Sr isotope compositions from the altered dolerite at Badu to provide new insight into the ore-fluid source of this key gold province. Petrography studies distinguished three apatite generations (Ap1 to Ap3): Pre-ore Ap1 is needle-shaped or fine-grained (<20 μm), and occurs mainly in the unmineralized dolerite; Main-ore Ap2 is euhedral-subhedral coarse-grained (>100 μm) and spatially associated with auriferous pyrite and arsenopyrite in the mineralized dolerite; Late-ore Ap3 is also euhedral-subhedral coarse-grained (>100 μm), and hosted in quartz ± ankerite veins crosscutting the mineralized dolerite. Geochemically, Ap1 contains relatively high Cl (∼0.134 wt%), MnO (∼0.038 wt%), MgO (∼0.155 wt%), and SiO 2 (∼0.285 wt%) contents, whereas Ap2 and Ap3 have relatively high SrO contents (∼0.448 and ∼0.45 wt%, respectively). This geochemical difference can be used to distinguish magmatic from hydrothermal apatite at Badu. Ap2 has similar chemistry to Ap3 except for the higher SO 3 contents (up to ∼0.318 wt%), and they both have similarly higher 87Sr/86Sr ratios (0.709489–0.711787) than those of the unmineralized dolerite (0.706295–0.706323) and the sedimentary ore host in the basin, but similar to the Lower Cambrian basement rocks (0.70909–0.82733). This similarity indicates that the ore-forming fluids were dominantly sourced from the basinal basement or from deep magmatic fluids with radiogenic Sr addition from the basement rocks. The ore-forming fluids may also have leached MREEs from the sulfate-rich basement rocks, leading to the observed MREE enrichments in Ap2 and Ap3. Our study highlights that the basement material contribution is critical for the Carlin-type gold mineralization in the Youjiang basin. [ABSTRACT FROM AUTHOR]