Southern Hunan Province Research Articles

Unveiling Tin Mineralization in the Baoshan, Southern Hunan Province: Implications for Coexisting Cu and Sn Polymetallic Composite Metallogenic Systems

Unveiling Tin Mineralization in the Baoshan, Southern Hunan Province: Implications for Coexisting Cu and Sn Polymetallic Composite Metallogenic Systems

Trace Element Geochemical Characteristics of Plants and Their Role in Indicating Concealed Ore Bodies outside the Shizhuyuan W–Sn Polymetallic Deposit, Southern Hunan Province, China

Trace Element Geochemical Characteristics of Plants and Their Role in Indicating Concealed Ore Bodies outside the Shizhuyuan W–Sn Polymetallic Deposit, Southern Hunan Province, China

Genetic link between the Kangjiawan gold deposit and late Jurassic granitic magmatism, South China: Constraints from in situ calcite U-Pb dating, sulfur isotope and trace elements of pyrite

(Meta)sedimentary rock-hosted gold (Au) deposits are globally important Au resources, of which ore genesis and mineral exploration have been attracted considerable attention. However, the precise dating of Au mineralization of those Au deposits remains challenging due to the absence of suitable dating minerals, thus impeding a comprehensive understanding of their genesis. The Kangjiawan Au deposit, situated in the southern Hunan Province, South China, is one of representative (meta)sedimentary rock-hosted Au deposits. Due to the lack of mineralization age, the genesis of Kangjiawan Au deposit is still a matter of debate. Here we report the data of in situ calcite U-Pb dating, in situ trace elements and sulfur isotope analysis of pyrite, to further constrain the mineralization timing and the sources of ore-forming materials of the Kangjiawan Au deposit. Based on the detailed field investigation and petrographic observations, three mineralization stages have been identified: pyrite (Py1) + quartz (Stage I), gold-bearing pyrite (Py2) + polymetallic sulfides + quartz + calcite (Stage II), and gold-bearing pyrite (Py3) + calcite (Stage III). The results of mineralogical and trace elemental analyses indicate that Au are mainly hosted in Py2 (average 14.19 ppm) and Py3 (average 4.80 ppm), primarily as the form of “invisible gold”. In situ LA-ICP-MS U-Pb dating on calcite intergrowth with the gold-bearing pyrite (Py3) yields a Tera-Wasserburg lower intercept age of 151.7 ± 5.4 Ma. This age is well consistent with the published zircon U-Pb age (158.3 ± 1.2 Ma) of the nearby Shuikoushan granodiorite, the molybdenite Re-Os age (157.8 ± 1.4 Ma) of the Laoyachao skarn Pb-Zn deposit in the Shuikoushan ore field, and the garnet U-Pb age (159.1 ± 1.9 Ma) of the skarn Pb-Zn ore in depth of the Kangjiawan Au deposit. These suggested that the Au mineralization of the Kangjiawan deposit is coeval with the emplacement of the Shuikoushan granodiorite and Laoyachao Pb-Zn mineralization, which are important parts of the large-scale Middle-Late Jurassic Cu-Au-Pb-Zn Metallogenic event of the Qin-Hang Metallogenic Belt, South China. In addition, trace elemental contents, such as relative low Co, Ni, and Se (i.e., <0.01 to 100 ppm), and a narrow δ34S range of −2.94 ‰ ∼ +3.03 ‰ of pyrite, indicate that ore-forming materials were mainly derived from granitic magmas. Integrated with previous studies, it is suggested that the Au mineralization in the Kangjiawan deposit is genetically associated with the late Jurassic granitic magmatism and is probably as the distal products of the deep-seated concealed granitic intrusions and related proximal skarn Pb-Zn ore.

Geochronology and geochemistry of the Banjiaoyuan tin deposit, southern Hunan Province and its geological implications

Situated in the central part of the Southern Hunan segment of the Nanling Metallogenic Belt, the Banjiaoyuan tin deposit represents a significant Indosinian quartz vein type tin deposit. Based on field geological surveys and petrographic observations, the mineralization in the area can be divided into three stages: (I) early greisen stage, (II) cassiterite-quartz vein stage, and (III) late barren quartz vein stage. The dating results show that the 40Ar-39Ar plateau age of muscovite in stage I is 215.51 ± 0.87 Ma, and the Rb-Sr isochronous age of quartz mineral in stage II is 214.2 ± 3.1 Ma (MSWD = 1.3), both of which are coincide with the cassiterite U-Pb lower intercept age (215.7 ± 1.3 Ma, MSWD = 1.2), confirming the existence of metallogenic events in this region during the late Indosinian. The δD and δ18O of quartz in stage II range from −66.2 to −80.2 ‰, and 3.71 to 6.17 ‰, respectively, indicating that the ore-forming fluid is mainly derived from a mixture of magmatic-hydrothermal fluids and a small amount of meteoric water. We applied LA-ICP-MS chemical mapping and trace elements analysis to cassiterites, found that they underwent a transition from oxidation to reduction during precipitation when the fluids tend to be more volatile-rich and highly fractionated. The formation of the Banjiaoyuan tin deposit is closely related to the late Indosinian magmatic activity in the Yangmingshan region. Besides, the deep and peripheral parts of the mining area also have the potential for large-scale vein-type and greisen-type W-Sn mineralization.

Spatio-temporal evolution and driving factors of new urbanization in central China based on multi-source data.

Urbanization is an inevitable outcome of the development of human society to a certain stage, and it is also an irreversible pattern of the concentration degree of human society. Based on multi-source data such as remote sensing images, ecological environment and socio-economic data, the evaluation index system of new urbanization is constructed from multi-dimensions of population, economy, society, space and ecology. To explore the spatio temporal evolution and driving factors of urbanization in 80 prefecture-level cities in central China from 2013 to 2021 by using entropy method, spatial autocorrelation model and geographic detector. The results show that: (1) The level of new urbanization continues to grow, with the average value rising from 0.1562 in 2013 to 0.2557 in 2021, and the regional differences are obvious, forming a circle structure with Wuhan, Zhengzhou and other provincial capitals as the center and weakening radiation to surrounding cities. (2) The agglomeration of ecological urbanization is significant, and the agglomeration trend is gradually enhanced. The high-high agglomeration areas tend to Xinzhou City, most prefecture-level cities in Hubei Province and some prefecture-level cities in Southern Hunan Province, while the low-low agglomeration areas tend to Changzhi City, most prefecture level cities in Henan Province and some prefecture-level cities in Northern Anhui Province. (3) The night light index, total retail sales of consumer goods, investment in fixed assets, proportion of built-up areas and urban economic density are the main driving factors affecting the level of new urbanization. (4) The interaction of driving factors shows double factor enhancement and nonlinear enhancement effects.

Evolution and zoning of spatial ecosystem functional stability in the southern hilly region of China: a “structure–function” perspective

IntroductionA series of significant ecological construction projects in the southern hilly region have brought about substantial changes to the ecological status and comprehensive zoning of the region. Hunan Province, with its strategic significance, was chosen as a representative research subject in the southern hilly region.MethodsWe conducted a dynamic evaluation of the ecological status change and comprehensive zoning of Hunan Province from a structure–function perspective by applying the transfer matrix, Theil-Sen, Mann-Kendall, and ecosystem service trade-offs or synergies methods. The research goal was to integrate and harmonize structural complexity and functional diversification, providing valuable insights for optimizing both ecological background and territorial background.ResultsThe main results are as follows: (1) The structural changes of ecosystems were mainly concentrated in settlement and Cropland ecosystems. While the area of bulti-up ecosystems has increased significantly, from 1.34% in 2000 to 2.72% in 2020. Cropland ecosystems marking a decrease of 1.39%, with a continued conversion of Cropland into construction land ecosystems. (2) Ecosystem function changes have introduced instability. Over time, NPP exhibited an oscillating trend of increase followed by a decrease. Spatially, there was a sharp decline in peripheral building land, and the regions of declining NPP displayed a lateral U-shaped distribution. (3) The overall trend in ecosystem service changes was positive. Quantitatively, GP and CS experienced an ascending-then-decreasing pattern, while HQ showed a weak decline and WY increased annually. At the county scale, there was noticeable spatial heterogeneity. Human socio-economic activities and environmental protection policies exert a significant impact on the ecological conditions within the study area. (4) Regarding the national territory space function partition, urban functional zones have primarily catered to residential functions and were mainly distributed in the Changsha-Zhuzhou-Xiangtan area.DiscussionEcological functional zones were mainly centered on ecological functions, and most were located in the mountainous areas of western and southern Hunan Province. The agricultural function areas were mainly to serve production functions and were mainly located in the Dongting Lake Plain, the nearshore plain of the mainstream and tributary systems of the rivers of Xiang, Zi, Yuan, and Li. In general, the changes in ecosystem structure and function in the study area reflect changes in ecological conditions. In the future, ecosystem diversity, stability, and sustainability should be improved from an integrated structure–function perspective.

Diagnostic Value and Challenges of BRAF V600E Molecular Testing and Thyroid Fine-Needle Aspiration Cytology: A Retrospective Study from a Tertiary Institution in Southern Hunan Province, China

Introduction: Combined thyroid fine-needle aspiration (FNA) cytology and valine-to-glutamate substitution at codon 600 of B-Raf proto-oncogene, serine/threonine kinase (BRAF V600E) mutation detection are procedures used for diagnosing thyroid nodules in many Chinese tertiary institutions. This retrospective study at our institution aimed to explore the effectiveness and challenges of the combined approach in diagnosing thyroid nodules and the correlation between BRAF V600E mutation status and behavior of papillary thyroid carcinoma. Methods: Thyroid FNA cytology and BRAF V600E mutation detection results were reviewed between November 2020 and July 2022. A total of 623 patients, each of whom underwent thyroidectomy and final pathological examination after FNA cytology diagnosis, were included in the study. The relationship between the BRAF V600E mutational status and pathological parameters was analyzed using the χ² test. The effectiveness and challenges of FNA cytology alone and the combined procedure were also evaluated based on the final pathology. Results: Of 623 patients, 591 were diagnosed with papillary thyroid carcinoma (PTC), of which 456 were positive for the BRAF V600E mutation. It demonstrated near-perfect specificity for identifying PTC, and its incidence rate showed an age-specific curve with an inverted U-shaped distribution. The final pathological examination showed that the combined procedure had a higher sensitivity (83.91%) than FNA cytology alone (63.45%) for distinguishing PTC from other lesions (p < 0.001). Mutational status was associated with a larger maximum tumor diameter (p = 0.003) and a tendency of capsular invasion (p = 0.0542) but possibly unrelated to central lymph node metastasis (p = 0.1846). Nodular goiters accounted for most benign entities initially designated as Bethesda categories III–V. Conclusion: BRAF V600E mutational analysis complements cytopathology and improves the PTC detection rate in FNA cytology samples due to the high prevalence of the mutation in China. BRAF V600E mutation does not show a statistical correlation with tumor aggressiveness. Morphological pitfalls such as histocyte aggregation, cystic-lining cells in nodular goiters, and oncocytes in Hashimoto’s thyroiditis, were overwhelmingly found in BRAF V600E-negative specimens.

Nature and timing of Sn mineralization in southern Hunan, South China: Constraints from LA-ICP-MS cassiterite U-Pb geochronology and trace element composition

Abstract Accurately determining the timing and mechanism of metallogenesis of ore deposits is essential for developing a robust genetic model for their exploration. In this paper, we analyze the formation conditions of cassiterite in five major deposits of southern Hunan Province, one of the most important tungsten-tin (W-Sn) provinces in South China, using a combination of cathodoluminescence imaging, in situ U-Pb geochronology, and trace-element concentration data. In situ cassiterite U-Pb geochronology constrains the main period of Sn mineralization to between 155.4 and 142.0 Ma, demonstrating a temporal and genetic relationship to silicic intrusive magmatism in the same area. Three stages of magmatic activity and metallogenic evolution are recognized: (1) Early Paleozoic and Triassic: the initial enrichment stage of tungsten and tin; (2) Jurassic: the metasomatic mineralization stage; and (3) Cretaceous: the magmatic-hydrothermal superposition stage. The cassiterite in these deposits takes four forms, i.e., quartz vein-type, greisen-skarn-type, greisen-type, and granite-type, representing a progression characterized by the increasing content and decreasing range of variation of high field strength elements (HFSEs), and reflecting a general increase in the degree of evolution of the associated granites. Rare earth element (REE) concentrations suggest that precipitation of cassiterite was insensitive to the redox state of the fluid and that precipitation of cassiterite in the southern Hunan Sn deposits did not require a high-fO2 environment. These findings provide new insights into tin mineralization processes and exploration strategies.

A contribution to cavernicolous beetle diversity of South China Karst: eight new genera and fourteen new species (Coleoptera: Carabidae: Trechini)

The specific diversity of Chinese cave fauna of the ground beetle tribe Trechini is further enriched. Eight new genera and species of trechine beetles are reported from limestone caves in southern China karsts: Youtrechus zijunae n. gen., n. sp. (Xianning, southeastern Hubei Province), Wumengius fengi n. gen., n. sp. (Liupanshui, western Guizhou Province), Chenotrechus parvulus n. gen., n. sp. (Laibin, central Guangxi Zhuang Autonomous Region), Sinaphaenopoides zhaoyiae n. gen., n. sp. (Chenzhou, southern Hunan Province), Ecotrechus ruruiae n. gen., n. sp. Hurites yunxianicus n. gen., n. sp. (Shaoyang, central Hunan Province), Pangaphaenops seraphicus n. gen., n. sp. (Bama, northwestern Guangxi Zhuang Autonomous Region) and Zunotrechus zhaojieyui n. gen., n. sp. (Zunyi, northern Guizhou Province). All the above genera are monospecific. Generic diagnosis of each new genus, with discussions on its possible phylogenetic position within the tribe Trechini, and description of the type species are provided. The following new species of cavernicolous trechines are described: Dongodytes (Dongodytodes) pingjingae sp. n. (Hechi, northern Guangxi Zhuang Autonomous Region), Dongodytes (s. str.) mingruoae n. sp. (Du'an, Hechi, northern Guangxi Zhuang Autonomous Region), Deuveaphaenops (Furongius) huangheae n. sp. (Daozhen, Zunyi, northern Guizhou Province), Shilinotrechus zhangfani n. sp. (Mile, Honghe Hani & Yi Autonomous Prefecture, southeastern Yunnan Province), Guizhaphaenops (s. str.) wanghaoi n. sp. (Qinglong, Qianxinan Buyi & Miao Autonomous Prefecture, southwestern Guizhou Province), and Graciliblemus gui n. sp. (Liping, Qiandongnan Miao & Dong Autonomous Prefecture, southeastern Guizhou Province). Further generic characteristics of the genus Graciliblemus Deuve & Tian, 2016 are added. A distribution map for all above new taxa is given.

Prevalence of human papillomavirus genotypes and related cervical morphological results in southern Hunan Province of China, 2018-2020: Baseline measures at a tertiary institution prior to mass human papillomavirus vaccination.

Human papillomavirus (HPV) infection is closely correlated with cervical lesions. However, the HPV prevalence varies among different districts. This retrospective study investigated the HPV genotype distribution and its relationship with cervical lesions in southern Hunan Province. The database at our Pathology Department was searched for HPV and morphological results during 2018-2020 were reviewed. A total of 49,955 gynaecological inpatients and outpatients, each of whom underwent HPV testing based on the amplification of L1 sequence and reverse dot blot hybridization, were included in this study. Available cytology and relevant histological examination results were reviewed. Enrolled cases were categorized into seven groups based on their age. Household registry and educational level were evaluated. Seven thousand two hundred eighty-six females were positive for HPV and the overall HPV positivity rate was 14.59%. The top five most prevalent HPV genotypes were HPV52, 16, 58, 53 and 51 (22.98%, 17.54%, 14.29%, 7.47%, and 5.70%, respectively). The HPV prevalence curve specific to the seven age groups showed a bimodal distribution. High school education or blow and rural residence served as risk factors for HPV infection. Single infection was the main type of HPV infection, and multiple infections occurred in 21.92% of the infected women. Of 3,148 cases had cytological results, 1,149 (36.50%) had abnormal cytological abnormalities. Among 2,833 participants with histological examination, 2000 (70.60%) had cervical abnormalities. Cytological and pathological abnormalities were mainly associated with infection with HPV16, 52 and 58. Further analysis found that HPV16, 58, 52 and 33 were the main genotypes associated with high-grade squamous lesions (HSIL) and that HPV16, 31, 33 and 58 were independent risk factors for HSIL (odd ratio [OR] = 1.70, 1.99, 2.59, 2.29; 95% CI = 1.41-2.03, 1.17-3.41, 1.88-3.59, 1.85-2.82; all p < 0.05). HPV16, 58, 52, 18 and 33 were the most frequent genotypes detected in squamous cell carcinoma (SCC) patients, and HPV16 and 18 were independent risk factors for cervical carcinomas (OR = 6.72;95% CI = 5.48-8.25; p < 0.001; OR = 1.67, 95% CI = 1.22-2.30; p = 0.001). This retrospective study demonstrated the prevalence and the distribution characteristics of HPV infection and its correlation with cervical lesions in southern Hunan Province. The comprehensive results of this survey can guide HPV vaccine research to protect against some common genotypes in China.

Study on Yanshanian metallogenic granitoids magmatism in Baoshan deposit, southern Hunan Province

本文对湘南宝山花岗闪长斑岩进行了系统的锆石和磷灰石U-Pb定年、岩石地球化学以及锆石Hf同位素研究，并探讨了宝山花岗闪长斑岩的岩石成因和构造意义。锆石和磷灰石的LA-ICP-MS U-Pb定年显示，宝山花岗闪长斑岩的成岩年龄为160Ma。综合元素和同位素地球化学证据，宝山花岗闪长斑岩的成因可能为新生地壳与古老地壳的混合熔融，同时宝山花岗闪长斑岩中发现的890&#177;20Ma的继承锆石，验证了新元古代新生地壳的参与。磷灰石的主微量元素研究显示花岗闪长斑岩具有较高的氧逸度和Cl含量，Sr/Th比值具有较大变化，而La/Sm比值变化不大等特征，表明形成花岗闪长斑岩岩浆的母岩受到俯冲板片脱水形成的流体交代作用影响。在上述过程中，富含Cl和H₂O的流体从板片中释放出来，引发地幔楔熔融，并对矿床中成矿金属元素进行提取。由于古太平洋板块俯冲引发的伸展-减薄运动，在地幔上涌过程中，新元古代新生地壳发生部分熔融，这些高温岩浆底侵老地壳源区，诱发老地壳部分熔融，进而发生了强烈的壳-壳混合作用，产生花岗闪长质岩浆。

Calcite U-Pb, pyrite Re-Os geochronological and fluid inclusion and H-O isotope studies of the Dafang gold deposit, South China

The Dafang gold deposit is one of the representative gold mineralization in southern Hunan province, South China. The gold orebodies mainly occur in the contact zones between late Jurassic granodiorite porphyry and late Paleozoic limestone as well as the fractures in them. Three primary mineralizing stages have been identified: pyrite + arsenopyrite ± chalcopyrite + quartz (stage I), pyrite + gold + calaverite + polymetallic sulfides + quartz (stage II), and pyrite + arsenopyrite + quartz + calcite (stage III). Pyrite samples separated from stage II yielded a Re-Os isochron age of 149 ± 16 Ma. Calcite samples from stage III demonstrated a U-Pb age of 157.7 ± 6.5 Ma. The above ages are similar to the zircon U-Pb ages of the local granodiorite porphyry although field evidences did not support a genetic link between them. The newly obtained mineralizing ages for Dafang indicate that this deposit is most likely related to deep or nearly late Jurassic intrusions (e.g., the Baoshan porphyry intrusion) and that this gold mineralization is synchronous with the large-scale W-Sn mineralization (160–150 Ma) for the Nanling Range in South China. The measured δDH2O (−103.5 to −81.4 ‰) and calculated δ18OH2O (−4.1 to + 4.9 ‰) isotope compositions for different stage vein quartz suggest that the Dafang ore-forming fluids were initially dominated by magmatic water, and were diluted by meteoric water in the late stage. Fluid inclusion studies indicate that the ore fluids belong to the H2O-NaCl-CO2-CH4 system, which cooled during its evolution (e.g., 230–337 °C, 150–246 °C, and 91–178 °C for stages I to III, respectively) with varied fluid salinity (4.7–9.2, 4.7–23.3, and 2.1–9.9 wt% NaCl eqv. for stages I to III, respectively). Fluid inclusions assemblages with different vapor and liquid phase ratios in a single quartz growth, and their similar homogenization temperatures with varying fluid salinities supported the fact that fluid boiling occurred in ore stage II. Combined with geological occurrences and the results from this study, we propose that gold was mainly transported in a reducing condition, and fluid boiling and host-rock sulfidation are the key factors for gold deposition at Dafang.

Evolution of Sustainable Water Resource Utilization in Hunan Province, China

The demand for social and economic development has promoted research into water resources. The combined effects of natural conditions and human activities on regional water resource usage are not well understood. The sustainable utilization of water resources was assessed in terms of supply (e.g., precipitation) and demand (e.g., ecological water resources footprint (EFw)) sides in Hunan Province, China, from 2010 to 2019. The results showed that: (1) on the supply side, water resources were increased across Hunan Province. The spatial patterns of total water resources are significantly heterogeneous, with high values in the east and south, which are mainly affected by precipitation; (2) on the demand side, evapotranspiration was great in areas with high vegetation coverage. The EFw was high in relatively developed areas. The mean percentage of agricultural EFw remained dominant at approximately 60% with a steady decreasing trend, while that of eco-environmental EFw increased; and (3) the sustainable utilization of water resources in Hunan Province is generally rational. Moreover, the potential for water resource development and utilization is really significant in eastern and southern Hunan Province. The findings are beneficial in providing an important scientific basis for policymaking relating to the efficient utilization of regional water resources.

Trace-element composition of pyrite in the Baoshan Cu–Mo–Pb–Zn deposit, southern Hunan Province, China: Insights into the ore genesis

The southern Hunan Province in southeastern China is the site of extensive Mesozoic magmatism and the formation of associated polymetallic deposits, among which, the studies for Cu–Pb–Zn mineralization are relatively rare compared with the W–Sn polymetallic deposits. In this study, the Baoshan skarn Cu–Mo–Pb–Zn deposit is investigated as a typical example with sulfide ores hosted in the distal carbonate. By presenting in situ laser ablation–inductively coupled plasma–mass spectrometry trace-element compositions of the ubiquitous pyrite, as well as arsenopyrite, sphalerite, and chalcopyrite, from carbonate strata, granodiorite porphyry, early disseminated and massive Cu–Mo–Pb–Zn ores, and late brecciated Cu ores, we aim to elucidate the relationships between the proximal skarn Cu–Mo and the distal carbonate hosted Pb–Zn mineralization in this deposit. Together with the geological characteristics, our results suggest that the pyrite trace-element compositions can be used to infer the precipitation environment. The pyrite from the early disseminated and massive Cu–Mo–Pb–Zn ores has high As/Sb and low Ni/As ratios, indicating that the ore-forming fluids and materials directly separated from the granodioritic magmas have dominated the sulfide mineralization in this stage, with minor contributions from the carbonate; the Pb–Zn mineralization is most likely precipitated from the same hydrothermal system with the early Cu–Mo mineralization, despite of the distal locations. On the contrary, the pyrite from the late brecciated Cu ores is characterized by low As/Sb and high Ni/As ratios, indicating that the ore-bearing fluids have circulated through the basements beneath the mining area, which should have also leached the ore-forming materials for the subsequent Cu mineralization. In addition to the direct contributions from the magmas and carbonate strata, this study emphasizes the substantial contributions from the basements to the Cu–Mo–Pb–Zn mineralization at Baoshan. This also indicates that the deep locations or the adjacent areas with well-developed fractures can be the potential targets for further exploration.

Ensemble learning models with a Bayesian optimization algorithm for mineral prospectivity mapping

Machine learning algorithms have been widely applied in mineral prospectivity mapping (MPM). In this study, we implemented ensemble learning of extreme gradient boosting (XGBoost) and random forest (RF) models to create MPM for magmatic hydrothermal tin polymetallic deposits in Xianghualing District, southern Hunan Province, China. Machine-learning models often require careful adjustment of the learning parameters and model hyperparameters for optimal global performance. However, parameter tuning often entails tedious calculations and sufficient expert experience, which is a time-consuming and labor-intensive process. To obtain the global optimal performance of the XGBoost and RF models, a Bayesian optimization algorithm (BOA) was employed with the aid of 5-fold cross validation to search for the most appropriate hyperparameters of the XGBoost and RF models. After the Bayesian optimization, the AUC values of both models were significantly improved, indicating that the BOA is a powerful optimization tool. The optimization results provide a reference for the empirical hyperparameter setting of ensemble learning models. Through a comparative study, the XGBoost model was shown to be superior to the RF model in terms of accuracy, precision, recall, F1 score, and kappa coefficient. In addition, the receiver operating characteristic curves and prediction–area curves showed that the XGBoost model outperformed the RF model, indicating that the XGBoost model had better prediction ability and stability in the case area. In this study, the XGBoost model shows great potential for MPM, offering a significant improvement over the BOA method.

Ore genesis of the Huangshaping skarn W–Mo–Pb–Zn deposit, southern Hunan Province, China: insights from in situ LA-MC-ICP-MS sulphur isotopic compositions

AbstractThe Huangshaping deposit is unique in southern Hunan Province, China, as it hosts economic reserves of both W–Mo and Pb–Zn mineralization, which are usually associated with granite and granodiorite porphyry in this area, respectively. This study reports results of in situ LA-MC-ICP-MS sulphur isotopic composition analyses conducted on sulphides from both W–Mo and Pb–Zn mineralization from the Huangshaping deposit with the aim of constraining ore genesis for this deposit. All samples from the proximal W–Mo mineralization have relatively uniform and high δ34S values (8.7 ‰ to 16.0 ‰), close to the range for carbonate sediments in this deposit (13.8 ‰ to 18.1 ‰). These patterns suggest that the granite porphyry in this deposit was the sulphur source for W–Mo mineralization, and that the assimilation of evaporite from the carbonate sediments led to the high δ34S values of the granite porphyry. Sulphides from the Pb–Zn mineralization have δ34S values (2.2 ‰ to 10.3 ‰) lower than those of the W–Mo mineralization, and generally increase in this paragenetic order, with the lowest δ34S values being similar to those of the basement (3.8 ‰ to 7.7 ‰). These patterns indicate that the original sulphur for the Pb–Zn mineralization was most likely derived from the basement, with input of sulphur from the carbonate sediments increasing during the evolution of ore-forming fluids. On the basis of the measured sulphur isotopic compositions, it is suggested that the ore-forming materials for the W–Mo mineralization were derived from the granite porphyry, whereas ore-forming materials extracted from the basement dominated the Pb–Zn mineralization.

Trace elements in sulfide minerals from the Huangshaping copper-polymetallic deposit, Hunan, China: Ore genesis and element occurrence

The Huangshaping copper-polymetallic deposit, which is located in southern Hunan Province, China, is an important resource base for Pb–Zn minerals. This study used the major sulfides (sphalerite, pyrite, pyrrhotite), which formed during the Pb–Zn mineralization stage of the Huangshaping deposit, to determine the genesis of the Pb–Zn ore minerals and element occurrence. In-situ LA-ICP-MS analysis of minerals was conducted to determine their trace element concentrations and reveal the distribution and occurrence of trace elements in different sulfides. The formation temperature and genesis of the Pb–Zn ore minerals were also constrained based on the deposit geology and trace element data. Trace elements were significantly different among different sulfides in the Pb–Zn mineralization stage of the deposit. Sphalerite primarily enriches Mn, Cu, Ag, Sn, and Pb and is the main carrier mineral of Ga, In, and Cd. Pyrite relatively enriches Tl, Sb, W, and Se, and pyrrhotite primarily enriches Ge. In sphalerite, Fe, Mn, Cd, Ga, In, Cu, Sn, Ag, and Ge exist by substituting for other elements (such as Zn). The replacement method of Ge is Ge4++2Cu+↔3Zn2+, whereas that of In (Ga) is In3+(Ga3+) + Cu+↔2Zn2+. In pyrrhotite, Ge is incorporated through coupling substitution, and the abnormal concentrations of Pb, Ag, and Se are caused by galena that has replaced pyrrhotite. In pyrite, W occurs as a solid solution. When galena replaces pyrite, it causes abnormal concentrations of Pb, Tl, Sb, and Ag. The sphalerite is characterized by high concentrations of high-temperature ore-forming elements (e.g., Fe, Mn, In, and Sn) and relatively low concentrations of Cd, Ge, Ga, and other elements. Thus, the sphalerite was formed at a medium–high temperature (288–341 °C). The trace element characteristics of sphalerite are consistent with those of high-temperature hydrothermal deposits. The deposit geology, pyrite Co/Ni ratio (averaging 0.13, n = 29), S/Se ratio (averaging 173,905, n = 19), pyrrhotite Co/Ni ratio (averaging 0.10, n = 26), and binary diagram of trace elements in sphalerite indicate that Pb–Zn mineralization is related to the late-stage hydrothermal activity of skarn mineralization. The Pb–Zn mineralization and W–Mo(Fe) mineralization together constitute a skarn-type mineralization system.

Spatial and Temporal Changes in Wetland in Dongting Lake Basin of China under Long Time Series from 1990 to 2020

Wetland plays a pivotal role in sustaining ecosystems and adapting to climate change. This paper used remote sensing images from 1990, 2000, 2010, and 2020 to investigate the changes in wetland in the Dongting Lake Basin (DLB) and their possible causes. The land-use conversion matrix and contribution rate were calculated in 1990–2000, 2000–2010, and 2010–2020, and results showed that the total wetland area displayed an increasing trend, especially the reservoir ponds and channels across DLB from 1990 to 2020. Forest and agricultural land conversion into wetland accounted for the main proportion, with the greatest contribution rate (234.13%) of forest land and the smallest rate (−117.46%) of agricultural land between 1990 and 2000. On the contrary, agricultural land had the highest contribution rate (47.96%) for wetlands compared to other land-cover types from 2000 to 2010, followed by forest land (39.03%). The contribution rates of forest and agricultural lands to wetlands were 60.17% and 39.02% from 2010 to 2020, respectively. Wetlands showed a more significant net gain (a total of 259 km2) in Central and Southern Hunan Province. More specifically, the wetlands area in North Hunan Province decreased by 45 km2 from 1990 to 2000. It increased over the next two decades (155 km2 and 22 km2, respectively). Southern Hunan Province continued increasing from 1990 to 2010 (a total of 149 km2) while decreasing from 2010 to 2020 (a total of −297 km2). Forestation was the principal driving force promoting the continuous increase in wetlands. In addition, agricultural land was mainly related to wetland change in this region, characterized by reclaiming land from lakes in the earlier period and returning agricultural land to wetland in the later period. Built-up land occupied a small area of wetlands over the study period. The study is beneficial to understanding the wetlands’ dynamic changes in the past and present, as well as being useful for wetland management, consistent with sustainable development.

Multiple sources for the Baoshan polymetallic Cu–Mo–Pb–Zn deposit, southern Hunan Province, China: Insights from in situ LA–MC–ICP–MS sulfur isotopic compositions

Southern Hunan Province, China, is characterized by extensive Mesozoic magmatic rocks and coeval polymetallic deposits, including granite-related W–Sn and granodiorite-porphyry-related Cu–Mo–Pb–Zn mineralization. It is commonly accepted that ore-forming materials for Cu–Mo–Pb–Zn mineralization in the southern Hunan area were generally dominated by granodiorite porphyry, owing to the close spatial and temporal relationship between the two. However, the detailed mineralization process for this type of deposit remains unclear, especially with respect to the relationship between the proximal skarn-hosted Cu–Mo and distal carbonate-hosted Pb–Zn mineralization. In this study, high-resolution in situ LA–MC–ICP–MS sulfur isotopic compositions for different types of sulfide from the typical Baoshan polymetallic Cu–Mo–Pb–Zn deposit are used to investigate the characteristics of mineralization in this area. Our results show that three endmembers with distinct δ34S values contributed to the formation of the Baoshan deposit: (1) granodiorite porphyry with moderate δ34S values (2.6‰ to 3.7‰), (2) carbonate strata with high δ34S values (3.8‰ to 22.7‰), and (3) metamorphic or crystalline basement with low δ34S values (−7.0‰ to 4.5‰). Molybdenite from the proximal skarn-hosted Mo mineralization has high δ34S values ranging from 3.6‰ to 6.6‰, whereas pyrite (−1.0‰ to 4.8‰), chalcopyrite (−1.1‰ to 4.4‰), sphalerite (1.9‰ to 4.2‰), and galena (0.2‰ to 4.8‰) from both the proximal skarn-hosted and distal carbonate-hosted Cu–Pb–Zn mineralization have wide-ranging δ34S values depending on their locations. These values suggest that the granodiorite porphyry and carbonate sources dominated the sulfur input for the entire Mo mineralization and that the granodiorite porphyry source dominated most of the Cu–Pb–Zn mineralization with similar or higher δ34S values in the Baoshan deposit, with some contribution from the carbonate strata for the latter mineralization. Deep-seated metamorphic or crystalline basement likely provided sulfur for the other parts of the Cu–Pb–Zn mineralization with low δ34S values. In addition to the contributions by granodiorite porphyry and carbonate strata, our study emphasizes the substantial contribution of basement rock materials to Cu–Mo–Pb–Zn mineralization. The ore-forming materials accumulated in the basement by the intrusion of early mafic magmas, which were then added to the Baoshan granodioritic magmas by remelting and mingling with these magmas. Ore-forming materials may also have been extracted from the basement by hydrothermal circulation triggered by the intrusion of these late granodioritic magmas.

Robust monazite U-Pb and molybdenite Re-Os ages reveal the magmatic and metallogenic history of a highly evolved granitic system in the Xianghualing deposit, South China

Tin, tungsten, and rare metals are key strategic metals and are regarded as having potentially relationship with highly evolved granites. However, excessive U accumulation with magmatic evolution, complex melt-fluid interaction, and late hydrothermal alteration make it difficult to obtain accurate age information from the highly evolved granitic system. The Xianghualing deposit, located in southern Hunan Province, China, is a giant Sn-Nb-Ta-polymetallic deposit with various types of mineralization spatially associated with the Laiziling and Jianfengling highly evolved granite plutons, and is an ideal target to investigate the magmatic-hydrothermal process of highly evolved magmas and related Sn-Nb-Ta-polymetallic mineralization. Previous studies have reported a relatively wide range of intrusion ages and multi-stage mineralization ranging from Triassic to Cretaceous. However, the timing and genetic link between magma emplacement and Sn-Nb-Ta-polymetallic mineralization remain controversial. Here we employ multiple dating methods, including SHRIMP zircon U-Pb analysis, LA-ICP-MS zircon and monazite U-Pb analysis, and molybdenite Re-Os dating analysis with a view to obtain a precise geochronological framework of the Xianghualing deposit. The SHRIMP zircon U-Pb data from the Laiziling protolithonite granite yielded a weighted 206Pb/238U age of 156.4 ± 1.5 Ma, whereas the LA-ICP-MS monazite U-Pb age for the Laiziling albite granite and the greisenized granite show 207Pb-corrected lower intercept 206Pb/238U ages of 155.5 ± 0.7 and 155.3 ± 0.5 Ma, respectively, which represent the emplacement ages of the Laiziling granite stock. Compared with the scattered SHRIMP and LA-ICP-MS zircon U-Pb age, monazite from the albite granite and greisenized granite yields more precise age information. Our study shows that monazite can be used as a robust tool for dating highly evolved granites. Molybdenite from the Laiziling pegmatite yields a Re-Os isochron age of 157.8 ± 4.2 Ma, which is consistent with the emplacement age of the Laiziling pluton. This result, integrated with previously reported metallogenic age, suggests a temporal and genetic link between the Laiziling granite and Sn-Nb-Ta polymetallic mineralization. Although multi-stage Sn-W metallogenic events have been identified in Nanling Region, it is suggested that the Xianghualing Sn-Nb-Ta mineralization formed during the Late Jurassic within a short duration coeval with the regional large-scale W-Sn mineralization at 160–150 Ma.