Journal of Geochemical Exploration最新文献

{"title":"Controls of Neoproterozoic magmatism on NiCu sulfide mineralization in the Jiangnan Orogenic Belt, South China: An example from the newly discovered Sibao NiCu sulfide deposit","authors":"Luqing Zhou ,&nbsp;Yonghua Cao ,&nbsp;Matthew J. Brzozowski ,&nbsp;Jianqing Lai ,&nbsp;Xiang-hua Liu ,&nbsp;Guiang Hu ,&nbsp;Zhongyu Zhang ,&nbsp;Joan Carles Melgarejo","doi":"10.1016/j.gexplo.2025.107694","DOIUrl":"10.1016/j.gexplo.2025.107694","url":null,"abstract":"<div><div>The newly discovered Sibao Ni<img>Cu sulfide deposit, situated in the western part of the Neoproterozoic Jiangnan Orogenic Belt (JOB), may be representative of Ni<img>Cu sulfide deposits that formed in convergent margins during the Neoproterozoic. The formation of this deposit may also have been influenced by activity of the mantle plume associated with the Neoproterozoic fragmentation of Rodinia. These characteristics make the Sibao deposit unique, because most convergent margin-related Ni<img>Cu sulfide deposits in China are of Paleozoic to early Mesozoic age and are typically not associated with mantle plume activity. Despite its geological significance, a paucity of research has been carried out on the Sibao deposit; the emplacement setting and mineralizing processes that operated to form this deposit, therefore, remain unclear. To address these ambiguities, we characterized the geochronological, geochemical, and isotopic characteristics of this deposit, focusing on zircon U<img>Pb dating, whole-rock trace-element chemistry and Sr<img>Nd isotopes, in situ S isotopes of sulfides, and trace-element chemistry of zircon and apatite. The host rocks to the Sibao deposit crystallized at ca. 837.7 ± 3.5 Ma, synchronous with ocean–continent subduction during formation of the JOB, but occurring prior to the mantle superplume event associated with the breakup of Rodinia (ca. 825–800 Ma). The systematically negative Nb<img>Ta anomalies and εNd(t) values (−5.6 to −2.2) suggest that the magma parental to the Sibao intrusion originated from metasomatized, enriched sub-continental lithospheric mantle (SCLM). This suggest that the Sibao deposit was emplaced in an Andean-style continental convergent margin, without any mantle plume contributions. Modeling of REE lambda values suggest that the mantle source of the Sibao parent magma contained a considerable amount of garnet-free pyroxenite, which formed through the reaction of mantle peridotite with fluids/melts derived from subducted oceanic crust. The <em>f</em>O₂ of the Sibao magma was estimated to be in the range of FMQ + 0.3 to FMQ + 1.2 based on the trace-element compositions of zircon and apatite. As demonstrated by the non-MORB δ³⁴S values of sulfides (+1.62 to +3.67 ‰), the Sibao parent magma required the addition of crustal sulfur to attain sulfide saturation. Thus, partial melting of metasomatized SCLM and incorporation of crustal sulfur were critical to the formation of the Sibao deposit. Overall, the Sibao deposit exhibits mantle source characteristics and sulfide saturation processes similar to other deposits emplaced along Andean-style continental convergent margins, such as the Xiarihamu, Erbutu, Kebu, and Aguablanca deposits. Together, these factors imply that Neoproterozoic convergent margins also have the potential to host economically significant Ni<img>Cu sulfide deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107694"},"PeriodicalIF":3.4,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology and geochronology of the Xinqi WSn polymetallic deposit in the Tengchong block, western Yunnan, China","authors":"Meng-Fan Liu,&nbsp;Qing-He Yan","doi":"10.1016/j.gexplo.2025.107697","DOIUrl":"10.1016/j.gexplo.2025.107697","url":null,"abstract":"<div><div>Xinqi is one of the most significant tungsten‑tin polymetallic deposits in the Tengchong tin polymetallic metallogenic belt, Sanjiang area. However, the age of the mineralization and the potential parental granite for tungsten‑tin (W<img>Sn) deposits have not yet been constrained. In this study, the ore-forming process at Xinqi is categorized into five stages: potassic stage (Stage I), sodium stage (Stage II), greisen stage (Stage III), quartz-cassiterite-wolframite stage (Stage IV), and quartz-cassiterite-sulfide stage (Stage V). U<img>Pb dating of cassiterite and wolframite extracted from quartz vein ore in stages IV and V yields consistent ages of 65.4 ± 1 Ma and 64.65 ± 0.66 Ma, respectively, indicating that W<img>Sn mineralization occurred during the Late Cretaceous and is closely associated with the collision between the Indian and Eurasian plates. Integrating this data with previous findings on W<img>Sn mineralization ages in the Tengchong block suggests that tungsten‑tin mineralization in this area is closely linked to granite, predominantly occurring from the Early Cretaceous to the Paleogene. The ages of W<img>Sn mineralization at Xinqi align with the formation age of Guyong monzogranite (66.30 ± 0.23 Ma) but are approximately 15 Ma older than the Xinqi granite porphyry (51.66 ± 0.21 Ma). This correlation, along with the low oxygen fugacity of the monzogranite (the value of △FMQ from −2.54 to 1.50), indicates that the monzogranite plays a crucial role in tin enrichment and serves as the parental granite for W<img>Sn mineralization at Xinqi. The parental monzogranite exhibits low ε_Hf(t) values ranging from −10.94 to −19.54, suggesting that the ore-forming magma likely derived from ancient crust without mantle contamination. Furthermore, based on previous studies, we propose that a tin-rich continental crust exists in the Tengchong area, which has undergone a series of specific collisional orogenic events that led to the formation of granite and the associated tin mineralization in the Tengchong block.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107697"},"PeriodicalIF":3.4,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning-driven classification of PbZn ore deposits using pyrite trace elements and isotopic signatures: A case study of the Gunga deposit","authors":"Muhammad Amar Gul ,&nbsp;Huishan Zhang ,&nbsp;Yanguang Li ,&nbsp;Xiaoyong Yang ,&nbsp;Chao Sun ,&nbsp;Xiaojian Zhao ,&nbsp;Guangli Ren ,&nbsp;Asia Kanwal ,&nbsp;Muhammad Hafeez ,&nbsp;Yu Yang ,&nbsp;Rizwan Sarwar Awan ,&nbsp;Mohamed Faisal","doi":"10.1016/j.gexplo.2025.107693","DOIUrl":"10.1016/j.gexplo.2025.107693","url":null,"abstract":"<div><div>The mineral pyrite, commonly associated with Pb<img>Zn deposits, can contain a variety of trace elements and is influenced by factors such as temperature, fluid composition, and metal source. These trace elements have long been used to differentiate between various types of Pb<img>Zn deposits. However, traditional discriminant diagrams, which typically rely on two or three dimensions, fail to comprehensively capture the complex relationships between pyrite trace elements and deposit types. To address this limitation, this study employed four machine learning algorithms—random forest (RF), support vector machine (SVM), gradient boost (GB), and multilayer perceptron (MLP)—to develop classification models based on pyrite trace element compositions. The models were trained on a dataset of 5400 data points from 134 mineral deposits or stratigraphic units with trace element data from published sources. The performance of the classifiers was evaluated via cross-validation using a variant of the leave-one-group-out (LOGO) method. The study applied these machine learning models to newly obtained geochemical data from pyrite samples collected at the Gunga Pb<img>Zn deposit in the Lasbela-Khuzdar metallogenic belt. The results demonstrated that the classifiers could accurately identify the source of Pb<img>Zn deposits, producing reliable predictive outcomes. Specifically, the models indicated that the geochemical signature of pyrite from the Gunga deposit was derived from sedimentary-hydrothermal fluids enriched in Pb, Zn, Sb, Tl, As, and Ge, which is consistent with geological and geochemical evidence. The in-situ δ³⁴S values of pyrite ranged from −24 ‰ to +25 ‰, suggesting that the sulfur in the deposit originated primarily from coeval seawater sulfate. Additionally, Pb isotope compositions indicated crustal sources for Pb<img>Zn in the Gunga deposit. The combined predictions from the classifiers, along with isotopic analyses of sulfur and lead, suggest that the Gunga Pb<img>Zn deposit is a Clastic-Dominant (CD)-type deposit. These findings highlight the effectiveness of machine learning techniques in classifying ore deposits and provide new insights into the origin of the Gunga Pb<img>Zn deposit.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107693"},"PeriodicalIF":3.4,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ UPb geochronology, geochemistry, and spatial-temporal evolution of multi-generational garnet from the Muzuke FeCu polymetallic skarn deposit, Chinese Western Tianshan, NW China","authors":"Ying-Shuai Zhang ,&nbsp;Yong-Mei Zhang ,&nbsp;Xue-Xiang Gu ,&nbsp;Yi-Wei Peng ,&nbsp;Jia-Lin Wang ,&nbsp;Tao Wang ,&nbsp;Jia-Liang Xiao","doi":"10.1016/j.gexplo.2025.107686","DOIUrl":"10.1016/j.gexplo.2025.107686","url":null,"abstract":"<div><div>Spatial and temporal processes of variations in garnet composition and corresponding fluid evolution during the prograde skarn stage are matters of ongoing controversy. Here, we combine in situ U<img>Pb geochronology and major- and trace-element compositions of garnet (Grt) in the Muzuke Fe<img>Cu polymetallic skarn deposit to address the above debate. Three generations of garnets were identified concerning their locations in the contact zone, colors, textural and optical characteristics, and chemical compositions. They belong to the grossular-andradite solid solution and are characterized by a temporal and spatial chemistry zonation, which ranges greatly in composition from nearly pure grossular (Grs₉₈Adr_0.6) during early prograde stage in endoskarn and proximal exoskarn to almost pure andradite (Grs_1.7Adr₉₇) during late prograde stage in distal exoskarn. We observed a clear correspondence between the major-element compositions and optical characteristics of garnet from Muzuke, and the formation of the birefringent garnets is probably induced by the symmetry reduction due to trivalent cation ordering varieties at the Y site in the regular octahedron. From Grt-1 to Grt-3, the overall REE patterns shift from HREE enrichment to LREE enrichment, accompanied by negative to positive Eu anomalies, which can be attributed to the relative proportion of grossular and andradite end-members, while the chemical composition of fluid in the late prograde stage also has some effects on the REE patterns of garnet. The transitions of geochemical characteristics between three generations of garnets suggest that despite the existence of multiple pulses of fluid flux in the prograde stage, the overall trend of fluids evolution indicates that from the early to terminal prograde stage, from endoskarn to distal exoskarn, the formation mechanism of skarn transitions from diffusion metasomatism under a closed system to advective metasomatism under an open system, accompanied by a gradual decrease in temperature of hydrothermal fluids and an increase in <em>f</em>O₂ and W/R ratios. The above process inhibited premature sulfide precipitation and may be a precursor to the precipitation of magnetite in the later stage. In situ U<img>Pb dating on garnet yields an age of 364.9 ± 7.6 Ma for Grt-2 and of 363.2 ± 4.5 Ma to 363.0 ± 2.0 Ma for Grt-3 from the Muzuke deposit, suggesting a genetic connection between the polymetallic mineralization and the emplacement of the nearby granodioritic intrusion. The garnet spatial-temporal evolution model established in this study could assist in localizing and exploring regional skarn ore bodies with similar causative intrusions and wall rock properties.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107686"},"PeriodicalIF":3.4,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance analysis signposts for sedimentary uranium exploration in aeolian sandstone systems: Insights from the Luohe Formation, Western Ordos Basin","authors":"Rui Tao ,&nbsp;Yang Song ,&nbsp;Liang Duan ,&nbsp;Mingtao Li","doi":"10.1016/j.gexplo.2025.107672","DOIUrl":"10.1016/j.gexplo.2025.107672","url":null,"abstract":"<div><div>The Lower Cretaceous Luohe Formation in the western Ordos Basin, North China, represents a rare aeolian sedimentary system with distinctive “uranium-bearing” characteristics. Sedimentary source of the uranium-bearing sandstones in this formation, which is crucial for advancing uranium exploration efforts, remains ambiguous. This study undertakes a comprehensive investigation encompassing petrology, geochemistry, and detrital zircon systematics (including zircon U–Pb ages, trace elements, and Hf isotopes) on the aeolian sandstones of the Luohe Formation within the western Ordos Basin. The objective is to provide crucial insights into conventional exploration for sedimentary uranium resources within aeolian sedimentary systems in intracontinental basins. Detrital zircon ages are categorized into a predominant age grouping within the Phanerozoic era (210–450 Ma), with notable peaks observed at 260 Ma and 420 Ma. Additionally, two minor age clusters are identified in the Early Paleoproterozoic (2240–2600 Ma), notably peaking at 2460 Ma, and the Late Paleoproterozoic (1600–2150 Ma), with a peak observed at 1850 Ma. Integrating the geochemical discrimination diagrams, it is suggested that the Alxa Block to the west of the Ordos Basin serves as the main provenance supplier of the hard detrital zircons. The uranium-bearing debris from the Alxa Block underwent sedimentary recycling and, therefore, were transported to the paleouplifts that formed on the western Ordos Basin during the Late Jurassic to Early Cretaceous. The paleoclimatic conditions characterized by prolonged arid periods interspersed with brief humid and warm episodes are crucial for the unique “uranium-bearing” nature of the sandstones. The sedimentary environment, dominated by aeolian deposition with localized fluvial deposition at basin-mountain interfaces, is identified as an ideal setting for uranium storage within aeolian sedimentary systems. We finally propose a generalized approach for exploring uranium reservoirs in aeolian sandstone systems at the basin level.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107672"},"PeriodicalIF":3.4,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics, water quality, health risks and sources of heavy metals of Qu River Basin","authors":"Dong Fu ,&nbsp;Yanchuan Gong ,&nbsp;Hua Liu ,&nbsp;Lvshan Zhou ,&nbsp;Wenjun Xiang ,&nbsp;Chenzheng Du","doi":"10.1016/j.gexplo.2025.107676","DOIUrl":"10.1016/j.gexplo.2025.107676","url":null,"abstract":"<div><div>With the continuous accumulation of heavy metals (HMs), the threat of HMs to the ecological environment has attracted high attention worldwide. The Qu River basin is located in the upper reaches of the Yangtze River, the largest river in China, but its water quality spatio-temporal distribution characteristics, pollution sources and health risks of HMs are still kept unclear. In this work, based on 2160 samples containing 8 HMs including Hg, Pb, Se, As, Cu, Cd, Zn and Cr from 36 sampling sites, the health risks, water quality variation characteristics and pollution sources in the Qu River Basin were studied. The mean HMs concentration varied in different seasons, with higher content of Zn, Cd, Cu, Pb and Cr in dry season, higher As value in wet season. The water quality distribution pattern of Qu River Basin shows that the upstream is superior to that in the middle and downstream. Health risks of Cd and Cr were most pronounced during the study period. Moreover, Cd poses a greater potential health risk in dry season while Cr in the rainy season, respectively. Positive matrix factorization (PMF) receptor model indicated that industrial pollution (26.2 %), soil erosion (24.3 %), natural source (22.4 %), atmospheric deposition (21.0 %) and agricultural activities (6.1 %) are identified as the potentially sources of HMs of the surface waters in Qu River Basin. Therefore, from the perspective of health risks, the treatment and discharge monitoring of industrial wastewater and the restoration of soil contaminated by HMs should be further strengthened in the Qu River basin. This work will provide basic data for water quality improvement and resource utilization of Qu River Basin.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107676"},"PeriodicalIF":3.4,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A geospatial analysis of coal mine overburden reclamation: Land use, carbon stock, biomass, and soil genesis in chronosequence plantations","authors":"Tarun Kumar Thakur ,&nbsp;Digvesh Kumar Patel ,&nbsp;Sandhya Saini ,&nbsp;Anita Thakur ,&nbsp;Singam Laxmana Swamy ,&nbsp;Sanjeev Bakshi ,&nbsp;Amit Kumar ,&nbsp;Fohad Mabood Husain ,&nbsp;Rupesh Kumar","doi":"10.1016/j.gexplo.2025.107674","DOIUrl":"10.1016/j.gexplo.2025.107674","url":null,"abstract":"<div><div>Coal remains a pivotal energy source, meeting 27 % of global energy demand and 70 % of India's energy requirements. However, coal mining significantly disrupts land use, necessitating effective reclamation strategies. This study examines the repercussions of coal mining on land use disruption and assesses the benefits of revegetation on structural attributes, biomass, carbon sequestration, and soil restoration in central India. Utilizing Landsat 9 satellite imagery, we characterized land use and vegetation dynamics, employing the Normalized Difference Vegetation Index (NDVI) to classify five distinct age sequence classes with median ages of 5, 10, 20, 30, and 40 years. Results indicated a decrease in tree density from 1408 to 588 trees per hectare as plantations aged from 5 to 40 years, while the basal area increased from 5.88 to 28.25 m² per hectare. Notably, values in 40-year-old stands approached those of natural forests. Key novelties include the identification of a strong correlation between spectral vegetation indices (SVIs) and soil quality indicators, providing a remote-sensing-based framework for monitoring ecological restoration. Both total standing biomass and carbon stock exhibited significant (<em>p</em> ≤ 0.05) increases with plantation age, ranging from 10.25 to 66.41 Mg ha⁻¹ and 5.16 to 32.74 Mg ha⁻¹, respectively. Soil carbon content decreased with depth, with values ranging from 7.68 to 18.98 Mg ha⁻¹ at 0–20 cm depth, and soil nitrogen values spanning 82.66 to 216.08 kg ha⁻¹. These findings underscore the necessity of site-specific management strategies that integrate technological, ecological, and economic considerations to advance ecological restoration and align with the Sustainable Development Goals by 2030.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107674"},"PeriodicalIF":3.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution dynamics and health risks of polyaromatic hydrocarbons and heavy metals in the anthropogenically impacted Omi-Asoro Stream, Nigeria","authors":"Adebanjo Jacob Anifowose ,&nbsp;Gideon Temitope Arowosaye ,&nbsp;Oluwaseyi Esther Adaramodu ,&nbsp;Esther Oluwaponmile Akintola ,&nbsp;Jesufunmilayo Abosede Otunniya ,&nbsp;Adedoyin Demilade Makinde ,&nbsp;Tesleem Olalekan Kolawole ,&nbsp;Shola Hezekiah Awojide","doi":"10.1016/j.gexplo.2025.107675","DOIUrl":"10.1016/j.gexplo.2025.107675","url":null,"abstract":"<div><div>The study carried out concerted analytical measurements of twenty polyaromatic hydrocarbons (PAHs) and eighteen heavy metals in the Omi-Asoro Stream, Ilesa, Nigeria to unravel their sources and the impacts of anthropogenic activities around it. Samples from the stream water were collected in March 2023. The resident PAHs were subjected to solid-phase extraction (SPE) and analyzed on a gas chromatograph-mass spectrometer. The acid-extracted heavy metals were also analyzed with an inductively coupled plasma-optical emission spectrometer (ICP-OES). Results showed that naphthalene (6.00 ± 7.79 μg/L) and fluoranthene (2.99 ± 4.24 μg/L) were the two dominant PAHs in the stream water. Similarly, Fe and Zn, with concentrations (μg/L) of 1291 ± 2361 and 53.1 ± 89.3, respectively, were the dominant heavy metals. Fe concentration constituted 84.4% of the total heavy metals in the water. Using principal component analysis (PCA), the PAH sources were traced to internal combustion engines, biomass burning, and pesticides/wood preservatives. The heavy metal sources were resolved to internal combustion of engines, metallic wear/rust, electronic devices, geogenic releases and agrochemicals. The risk assessment showed that among the detected PAHs, benzo(<em>a</em>)pyrene constituted a carcinogenic effect on humans. The heavy metals which posed carcinogenic effects included As, Ni, Cd and Cr. Thus, the industrial and agricultural activities, as well as emissions from the internal combustion of engines in the area released the environmental pollutants which adversely impacted the stream.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107675"},"PeriodicalIF":3.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unsupervised detection of multivariate geochemical anomalies using a high-performance deep autoencoder Gaussian mixture model","authors":"Xuemei Wang,&nbsp;Yongliang Chen","doi":"10.1016/j.gexplo.2025.107671","DOIUrl":"10.1016/j.gexplo.2025.107671","url":null,"abstract":"<div><div>It is of great significance to construct an efficient geochemical anomaly detection model for the successful accomplishment of a mineral exploration process in a complex geological environment. However, the complex geological environment of the prospecting area often results in the high-dimensional unknown complex population distribution of geochemical exploration data. This complex distribution is difficult to fit with a theoretical probability distribution model. As a result, it becomes a challenge to carry out an effective detection of geochemical anomalies. Therefore, to develop an anomaly detection model that can effectively fit the complex population distribution of geochemical exploration data is the key for accurately detecting geochemical anomalies. For this reason, the deep autoencoder Gaussian mixture model (DAGMM) was adopted to model the geochemical exploration data obtained in the 1:200,000 geological survey conducted in the Baishan area (Jilin, China) to check its superiority in identifying multivariate geochemical anomalies. As an innovative deep learning framework for unsupervised anomaly detection, DAGMM ingeniously combines the data dimensionality reduction and compression capabilities of a deep autoencoder (DAE) with the probability density estimation advantage of the Gaussian mixture model (GMM). The DAGMM model can deeply explore the deep-level features of geochemical exploration data and effectively model the complex unknown data distribution through the synergistically work and joint optimization strategy in training the DAE and GMM model, so it can accurately identify geochemical anomalies. To show the superiority of the DAGMM model in detecting polymetallic geochemical anomalies, the DAGMM model was compared with the GMM and DAE models. The receiver operating characteristic (ROC) curves of the three models were plotted, and the areas under the ROC curves (AUCs) and lift indices were calculated. The ROC curve of the DAGMM model dominates that of the DAE model and GMM model. The DAGMM model has an AUC of 0.904 and a lift index of 10.44, respectively, which are much larger than those of the GMM model (AUC = 0.858, lift index = 3.63) and DAE model (AUC = 0.83, lift index = 5.31). Therefore, the DAGMM model significantly outperforms the other two models in detecting multivariate geochemical anomalies and the polymetallic geochemical anomalies detected by the DAGMM model contain all the known polymetallic deposits. Compared with DAE and GMM, DAGMM is more efficient and more powerful in detecting multivariate geochemical anomalies in complex geological environments.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107671"},"PeriodicalIF":3.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling mineralization potential of catchment basins: Insight from geochemical fingerprint","authors":"Haicheng Wang ,&nbsp;Ruiwen Shen ,&nbsp;Liuan Duan ,&nbsp;Qiuming Cheng ,&nbsp;Zhaoxian Yuan ,&nbsp;Shengyuan Zhang","doi":"10.1016/j.gexplo.2025.107669","DOIUrl":"10.1016/j.gexplo.2025.107669","url":null,"abstract":"<div><div>Stream sediments are common sampling media in cost-effective regional exploration programs. Catchment basins are the basic sampling units of steam sediments, which have distinct geochemical characteristics. In this study, the mineralization potential of catchment basin using stream sediments is evaluated from the perspective of geochemical fingerprints. Firstly, the spatial distribution of catchment basins was acquired based on digital elevation model data. The local singularity analysis was employed to reduce the impact of the overburden, revealing the weak geochemical anomalies. The catchment basins with known mineral occurrences as the prior dataset were used to train the random forest model, which improved the model accuracy and interpretability. The geochemical fingerprints of different types of mineralization were constructed based on the importance of geochemical variables in the random forest modeling, which revealed the importance of geochemical elements for different types of mineralization occurrences. All catchment basins lacking mineral occurrences were categorized based on the trained random forest model, achieving the potential types of mineralization for each catchment basin. Most of catchment basins with the same types of mineralization occurrences exhibited the spatial cluster, suggesting the migration characteristics of metal element in stream sediments through river system. Geochemical fingerprinting is a valuable tool for classifying the different types of mineralization occurrences at the scale of catchment basins. The delineated potential mineral occurrence types for catchment basins provided an indicator for future mineral exploration endeavors.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"271 ","pages":"Article 107669"},"PeriodicalIF":3.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}