Pub Date : 2024-12-02DOI: 10.1016/j.gexplo.2024.107662
Shahed Shahrestani, Ioan Sanislav
In this paper, a statistical outlier detection technique based on empirical cumulative distribution functions (ECOD) is applied to a multivariate geochemical dataset from southeastern Iran, which is known for its porphyry and vein-type copper mineral occurrences. The ECOD method assumes that outlier samples are situated in both the left and right tails of the cumulative distribution functions, and it determines whether the outliers are located in the right or left tails using the concept of skewness. Anomaly maps produced by the ECOD method are compared with those generated by the local outlier factor (LOF) method. Both ECOD and LOF are applied to two subsets, including 4 and 12 trace elements. The anomaly maps are evaluated by comparing the number of delineated known mineral deposits and using ROC curves. The result revealed that LOF was outperformed by ECOD in the delineation of known Cu mineralization and in the identification of zones containing mineralized samples collected during the anomaly checking stage. The ECOD anomaly map is also compared with results from the k-means clustering method, and the superiority of ECOD over k-means clustering is demonstrated. The implementation of ECOD on clr-transformed multivariate geochemical data shows promise but assumes statistical independence among features, often unmet in geochemical exploration. To address this, we transformed clr data into new principal and independent feature spaces using principal component analysis (PCA) and independent component analysis (ICA), enhancing anomaly detection efficiency. ECOD_ICA outperformed ECOD_PCA, successfully classifying all mineralized samples and 15 of 18 Cu mineral occurrences in the highest score class (Q4), as confirmed by ROC analysis. However, the reliance of the ECOD method on univariate tail probabilities limits its ability to detect multivariate anomalies arising from complex inter-element relationships. Strong correlations in geochemical datasets can lead to false positives, necessitating dimension reduction techniques. While PCA and ICA help manage these correlations, they may obscure meaningful signals. The ECOD outlier detection method is also sensitive to the skewness of the dimensions, so a careful feature selection stage is recommended before applying it. The method is less sensitive to the number of dimensions, which enhances its robustness. Additionally, the absence of hyperparameter tuning makes ECOD a reliable and efficient outlier detection method.
{"title":"Delineation of geochemical anomalies through empirical cumulative distribution function for mineral exploration","authors":"Shahed Shahrestani, Ioan Sanislav","doi":"10.1016/j.gexplo.2024.107662","DOIUrl":"10.1016/j.gexplo.2024.107662","url":null,"abstract":"<div><div>In this paper, a statistical outlier detection technique based on empirical cumulative distribution functions (ECOD) is applied to a multivariate geochemical dataset from southeastern Iran, which is known for its porphyry and vein-type copper mineral occurrences. The ECOD method assumes that outlier samples are situated in both the left and right tails of the cumulative distribution functions, and it determines whether the outliers are located in the right or left tails using the concept of skewness. Anomaly maps produced by the ECOD method are compared with those generated by the local outlier factor (LOF) method. Both ECOD and LOF are applied to two subsets, including 4 and 12 trace elements. The anomaly maps are evaluated by comparing the number of delineated known mineral deposits and using ROC curves. The result revealed that LOF was outperformed by ECOD in the delineation of known Cu mineralization and in the identification of zones containing mineralized samples collected during the anomaly checking stage. The ECOD anomaly map is also compared with results from the k-means clustering method, and the superiority of ECOD over k-means clustering is demonstrated. The implementation of ECOD on clr-transformed multivariate geochemical data shows promise but assumes statistical independence among features, often unmet in geochemical exploration. To address this, we transformed clr data into new principal and independent feature spaces using principal component analysis (PCA) and independent component analysis (ICA), enhancing anomaly detection efficiency. ECOD_ICA outperformed ECOD_PCA, successfully classifying all mineralized samples and 15 of 18 Cu mineral occurrences in the highest score class (Q4), as confirmed by ROC analysis. However, the reliance of the ECOD method on univariate tail probabilities limits its ability to detect multivariate anomalies arising from complex inter-element relationships. Strong correlations in geochemical datasets can lead to false positives, necessitating dimension reduction techniques. While PCA and ICA help manage these correlations, they may obscure meaningful signals. The ECOD outlier detection method is also sensitive to the skewness of the dimensions, so a careful feature selection stage is recommended before applying it. The method is less sensitive to the number of dimensions, which enhances its robustness. Additionally, the absence of hyperparameter tuning makes ECOD a reliable and efficient outlier detection method.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107662"},"PeriodicalIF":3.4,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-27DOI: 10.1016/j.gexplo.2024.107641
Michèle Jungmann , Benjamin F. Walter , Elisabeth Eiche , R. Johannes Giebel , Jochen Kolb
Geothermal brines in the Upper Rhine Graben have been used as a spa or for salt production since Roman times. Heat and power are generated in geothermal power plants since 2007. Recently, their elevated Li-content has additionally attracted economic interest. This increased interest is in contrast with our understanding of the geological-hydrothermal evolution. We use petrology, major and trace element mineral chemistry and mass balance calculation from drill cores that intersect granitic geothermal reservoir rocks at Soultz-sous-Forêts between Strasbourg and Karlsruhe to shed light on fluid-rock interaction in a reservoir that is actively used for heat and power generation. The alkali feldspar and the two-mica granite in the reservoir have a typical plagioclase, K-feldspar, quartz, biotite and muscovite assemblage with some accessories of titanite, apatite and zircon. Two hydrothermal alteration events are distinguished: (1) albitization of the feldspars; (2) distal replacement of feldspars by sericite and calcite, of biotite by chlorite and titanite; and proximal to hydrothermal veins replacement of the feldspars by sericite and kaolinite. Event 2 feldspar alteration quantitatively releases Pb and Ba to the fluid, whereas Rb, Cs, Sr and Zn show different behaviour depending on whole-rock and mineral composition. Event 2 biotite-chlorite alteration releases Li, Rb, Cs, Sr, Ba, Zn and Pb to the fluid. Mass balance calculation indicates that Si, Fe, Ca, K, Rb, Sr, Zn and Pb contents of the Soultz-sous-Forêts geothermal brine may be explained by fluid-rock interaction in the reservoir. However, the reservoir rock volume that needs to be leached in order to reach recent brine composition varies by several orders of magnitude between the different elements. Many of the elements may be leached during hydrothermal alteration, however in particular Li and Cs require unrealistic fluid-rock ratios of >1/300. These considerations indicate that Na, Ca, Li, Cs and Ba need an additional external source. Based on this, we propose a model where Middle Triassic bittern brines already enriched in Li, Rb, and Cs reacted with the reservoir rocks during hydrothermal event 2 and subsequently mixed with Jurassic-Cretaceous marine water that dissolved evaporites during downward migration. This agrees with Jurassic-Cretaceous illite ages from various sites in the Black Forest and indicates a complex ∼150 m.y. hydrothermal evolution for the brines. There is likely no single source of Li, and it is likely derived from complex fluid-rock interaction with the sedimentary (evaporite) and, less importantly, the crystalline strata of the Upper Rhine Graben. Critical for Li-resource development is the complex hydrothermal history of connate fluids that interacted with sedimentary strata and the preservation in deep-seated reservoirs.
{"title":"The source of lithium in connate fluids: Evidence from the geothermal reservoir at Soultz-sous-Forêts, Upper Rhine Graben, France","authors":"Michèle Jungmann , Benjamin F. Walter , Elisabeth Eiche , R. Johannes Giebel , Jochen Kolb","doi":"10.1016/j.gexplo.2024.107641","DOIUrl":"10.1016/j.gexplo.2024.107641","url":null,"abstract":"<div><div>Geothermal brines in the Upper Rhine Graben have been used as a spa or for salt production since Roman times. Heat and power are generated in geothermal power plants since 2007. Recently, their elevated Li-content has additionally attracted economic interest. This increased interest is in contrast with our understanding of the geological-hydrothermal evolution. We use petrology, major and trace element mineral chemistry and mass balance calculation from drill cores that intersect granitic geothermal reservoir rocks at Soultz-sous-Forêts between Strasbourg and Karlsruhe to shed light on fluid-rock interaction in a reservoir that is actively used for heat and power generation. The alkali feldspar and the two-mica granite in the reservoir have a typical plagioclase, K-feldspar, quartz, biotite and muscovite assemblage with some accessories of titanite, apatite and zircon. Two hydrothermal alteration events are distinguished: (1) albitization of the feldspars; (2) distal replacement of feldspars by sericite and calcite, of biotite by chlorite and titanite; and proximal to hydrothermal veins replacement of the feldspars by sericite and kaolinite. Event 2 feldspar alteration quantitatively releases Pb and Ba to the fluid, whereas Rb, Cs, Sr and Zn show different behaviour depending on whole-rock and mineral composition. Event 2 biotite-chlorite alteration releases Li, Rb, Cs, Sr, Ba, Zn and Pb to the fluid. Mass balance calculation indicates that Si, Fe, Ca, K, Rb, Sr, Zn and Pb contents of the Soultz-sous-Forêts geothermal brine may be explained by fluid-rock interaction in the reservoir. However, the reservoir rock volume that needs to be leached in order to reach recent brine composition varies by several orders of magnitude between the different elements. Many of the elements may be leached during hydrothermal alteration, however in particular Li and Cs require unrealistic fluid-rock ratios of >1/300. These considerations indicate that Na, Ca, Li, Cs and Ba need an additional external source. Based on this, we propose a model where Middle Triassic bittern brines already enriched in Li, Rb, and Cs reacted with the reservoir rocks during hydrothermal event 2 and subsequently mixed with Jurassic-Cretaceous marine water that dissolved evaporites during downward migration. This agrees with Jurassic-Cretaceous illite ages from various sites in the Black Forest and indicates a complex ∼150 m.y. hydrothermal evolution for the brines. There is likely no single source of Li, and it is likely derived from complex fluid-rock interaction with the sedimentary (evaporite) and, less importantly, the crystalline strata of the Upper Rhine Graben. Critical for Li-resource development is the complex hydrothermal history of connate fluids that interacted with sedimentary strata and the preservation in deep-seated reservoirs.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107641"},"PeriodicalIF":3.4,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.gexplo.2024.107640
Xuelian Huang , Shuai Wang , Sijia Wang , Zhicai Xiao , Min Zhang , Hongyan Zhang , Shihua Qi
Geothermal water, a vital renewable energy source extensively harnessed for heating and power generation, is marred by a prevalent issue – high fluoride content. The environmental impact of geothermal fluoride has been recognized globally. The natural discharge of geothermal water, coupled with its widespread exploitation, instigates the translocation of geothermal fluoride toward shallow and surface water ecosystems, culminating in escalating fluoride concentrations, thereby posing potential threats to both ecosystems and human health. Nevertheless, despite the pivotal significance of fluoride in geothermal water, a comprehensive understanding of its origins, migratory dynamics, ecological consequences, and ameliorative methodologies remains to be studied. This review provides a comprehensive examination of fluoride's global occurrence and distribution in geothermal waters, emphasizing the contrast between volcanic and non-volcanic geothermal systems. It analyzes the various sources of fluoride in these waters and elucidates the mechanisms driving its mobilization. In volcanic geothermal systems, fluoride primarily derives from magmatic volatiles, while in non-volcanic systems, it mainly results from the dissolution of minerals. Temperature is a key factor influencing fluoride concentration in geothermal waters, with alkaline conditions and low calcium levels contributing to higher fluoride enrichment. The review details how fluoride concentrations change as geothermal fluids migrate from deeper to shallower layers. Based on the enrichment characteristics of fluorides, this paper explores the potential applications of geothermal fluorides. It also examines the environmental impacts of geothermal fluoride, presents various treatment methods, and provides a summary of current research both domestically and internationally, while proposing directions for future studies. This study is instrumental in formulating judicious fluoride management policies and establishing sustainable strategies for the development of geothermal resources.
{"title":"Fluoride in geothermal water: Occurrence, origin, migration and environmental impact","authors":"Xuelian Huang , Shuai Wang , Sijia Wang , Zhicai Xiao , Min Zhang , Hongyan Zhang , Shihua Qi","doi":"10.1016/j.gexplo.2024.107640","DOIUrl":"10.1016/j.gexplo.2024.107640","url":null,"abstract":"<div><div>Geothermal water, a vital renewable energy source extensively harnessed for heating and power generation, is marred by a prevalent issue – high fluoride content. The environmental impact of geothermal fluoride has been recognized globally. The natural discharge of geothermal water, coupled with its widespread exploitation, instigates the translocation of geothermal fluoride toward shallow and surface water ecosystems, culminating in escalating fluoride concentrations, thereby posing potential threats to both ecosystems and human health. Nevertheless, despite the pivotal significance of fluoride in geothermal water, a comprehensive understanding of its origins, migratory dynamics, ecological consequences, and ameliorative methodologies remains to be studied. This review provides a comprehensive examination of fluoride's global occurrence and distribution in geothermal waters, emphasizing the contrast between volcanic and non-volcanic geothermal systems. It analyzes the various sources of fluoride in these waters and elucidates the mechanisms driving its mobilization. In volcanic geothermal systems, fluoride primarily derives from magmatic volatiles, while in non-volcanic systems, it mainly results from the dissolution of minerals. Temperature is a key factor influencing fluoride concentration in geothermal waters, with alkaline conditions and low calcium levels contributing to higher fluoride enrichment. The review details how fluoride concentrations change as geothermal fluids migrate from deeper to shallower layers. Based on the enrichment characteristics of fluorides, this paper explores the potential applications of geothermal fluorides. It also examines the environmental impacts of geothermal fluoride, presents various treatment methods, and provides a summary of current research both domestically and internationally, while proposing directions for future studies. This study is instrumental in formulating judicious fluoride management policies and establishing sustainable strategies for the development of geothermal resources.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107640"},"PeriodicalIF":3.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164544","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}
Pub Date : 2024-11-23DOI: 10.1016/j.gexplo.2024.107643
Mohd Yawar Ali Khan
To reduce the costs associated with monitoring suspended sediment load (SSL) in rivers, creating more cost-effective and easily measurable indirect estimation methodologies that rely on interactions with other variables is necessary. This work introduces a new method to assess the capability of regional models to expand ungauged SSL to gauging locations in a diverse region with little in situ data and complex hydrography. The estimates were derived using discharge (Q) data, utilizing models based on artificial neural network (ANN) feedforward backpropagation (FFBP) techniques for the Ramganga River Basin. This work confirms the practical capacity and utility of ANN for simulating intricate nonlinear dynamics in natural river systems in the context of the Himalayas. The modelling method is based on the daily Q and SSL data collected from 2007 to 2009. The initial phase involved developing and training the ANN utilizing the FFBP Algorithm within the Matlab (MATLAB R2015a). The networks were optimized utilizing the process of enumeration. The optimal network was subsequently employed to forecast the SSL values, which are ungauged parameters, at the Moradabad (MBD) gauging site. The second stage involves validating the predicted (ungauged) SSL values of MBD by utilizing them to estimate the SSL values of Dabri (DBI) gauged sites. The predicted values obtained from the model are contrasted with the authentic observed values of SSL at DBI. The R2 value for the optimal network was found to be 0.998, accompanied by an MSE of 0.00112. The study offers valuable insights into the modelling of ANN and emphasizes the significance of comprehending a river basin and its influencing components to simulate the SSL effectively. This study demonstrates that the proposed methodology allows for highly efficient regional streamflow estimation in ungauged basins, even in diverse geographical areas.
{"title":"Regional ANN model for estimating missing daily suspended sediment load in complex, heterogeneous catchments","authors":"Mohd Yawar Ali Khan","doi":"10.1016/j.gexplo.2024.107643","DOIUrl":"10.1016/j.gexplo.2024.107643","url":null,"abstract":"<div><div>To reduce the costs associated with monitoring suspended sediment load (SSL) in rivers, creating more cost-effective and easily measurable indirect estimation methodologies that rely on interactions with other variables is necessary. This work introduces a new method to assess the capability of regional models to expand ungauged SSL to gauging locations in a diverse region with little in situ data and complex hydrography. The estimates were derived using discharge (Q) data, utilizing models based on artificial neural network (ANN) feedforward backpropagation (FFBP) techniques for the Ramganga River Basin. This work confirms the practical capacity and utility of ANN for simulating intricate nonlinear dynamics in natural river systems in the context of the Himalayas. The modelling method is based on the daily Q and SSL data collected from 2007 to 2009. The initial phase involved developing and training the ANN utilizing the FFBP Algorithm within the Matlab (MATLAB R2015a). The networks were optimized utilizing the process of enumeration. The optimal network was subsequently employed to forecast the SSL values, which are ungauged parameters, at the Moradabad (MBD) gauging site. The second stage involves validating the predicted (ungauged) SSL values of MBD by utilizing them to estimate the SSL values of Dabri (DBI) gauged sites. The predicted values obtained from the model are contrasted with the authentic observed values of SSL at DBI. The R<sup>2</sup> value for the optimal network was found to be 0.998, accompanied by an MSE of 0.00112. The study offers valuable insights into the modelling of ANN and emphasizes the significance of comprehending a river basin and its influencing components to simulate the SSL effectively. This study demonstrates that the proposed methodology allows for highly efficient regional streamflow estimation in ungauged basins, even in diverse geographical areas.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107643"},"PeriodicalIF":3.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720834","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}
Pub Date : 2024-11-23DOI: 10.1016/j.gexplo.2024.107642
Piotr Jachimowicz , Algirdas Radzevičius , Petra Wojnarová , Raimondas Šadzevičius , Bartłomiej Horoszko , Midona Dapkienė , Maja Radziemska , Barbara Klik
This study evaluates the temporal trends and seasonal variations in heavy metal concentrations within sewage sludge from the Kaunas wastewater treatment plant in Lithuania between 2000 and 2022. It integrates two decades of data with detailed seasonal analyses for 2021 and 2022, providing a comprehensive view of both long-term trends and short-term fluctuations. Monthly wastewater and sludge samples were collected, and concentrations of Cr, Zn, Hg, Cd, Ni, Cu, and Pb were analyzed using atomic absorption spectrometry. Statistical evaluations of temporal and seasonal data were conducted to identify trends and correlations between metal concentrations and external factors. Significant declines were observed in Cr, Pb, and Hg levels, highlighting the effectiveness of regulatory measures and treatment improvements. However, Zn and Cu concentrations remain elevated, posing challenges for sludge management and reuse. Seasonal spikes in Zn and Cr, particularly in May–July and October–December, were linked to industrial activities and stormwater runoff. The study also explores Lithuania's recent regulatory changes that permit higher Zn concentrations in sludge for agricultural use, reflecting evolving sludge management strategies.
{"title":"Two decades of heavy metal fluctuations in wastewater sludge in Lithuania with evolving trends and implications for treatment efficiency","authors":"Piotr Jachimowicz , Algirdas Radzevičius , Petra Wojnarová , Raimondas Šadzevičius , Bartłomiej Horoszko , Midona Dapkienė , Maja Radziemska , Barbara Klik","doi":"10.1016/j.gexplo.2024.107642","DOIUrl":"10.1016/j.gexplo.2024.107642","url":null,"abstract":"<div><div>This study evaluates the temporal trends and seasonal variations in heavy metal concentrations within sewage sludge from the Kaunas wastewater treatment plant in Lithuania between 2000 and 2022. It integrates two decades of data with detailed seasonal analyses for 2021 and 2022, providing a comprehensive view of both long-term trends and short-term fluctuations. Monthly wastewater and sludge samples were collected, and concentrations of Cr, Zn, Hg, Cd, Ni, Cu, and Pb were analyzed using atomic absorption spectrometry. Statistical evaluations of temporal and seasonal data were conducted to identify trends and correlations between metal concentrations and external factors. Significant declines were observed in Cr, Pb, and Hg levels, highlighting the effectiveness of regulatory measures and treatment improvements. However, Zn and Cu concentrations remain elevated, posing challenges for sludge management and reuse. Seasonal spikes in Zn and Cr, particularly in May–July and October–December, were linked to industrial activities and stormwater runoff. The study also explores Lithuania's recent regulatory changes that permit higher Zn concentrations in sludge for agricultural use, reflecting evolving sludge management strategies.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107642"},"PeriodicalIF":3.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719981","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}
Pub Date : 2024-11-22DOI: 10.1016/j.gexplo.2024.107644
Said Muhammad , Rizwan Ullah , Sehrish Amin , Ashfaq Ahmad
Radon (222Rn) has a ubiquitous nature in the environment and can pose serious health threats to living beings. Groundwater is the primary source of drinking and domestic uses for >3 million people in the area. The current study was conducted for investigation of groundwater for the 222Rn concentration and associated health risks. For that purpose, the groundwater was examined for 222Rn concentration using the RAD7 detector (Durridge Company, USA). Average concentrations of 222Rn were highest at 10.8 ± 3.6 Bq/L in the Lower Dir district and lowest at 6.39 ± 0.98 Bq/L in the Upper Dir. The average concentration of 222Rn was found below the threshold limit set by the US Environmental Protection Agency (USEPA) and the World Health Organization (WHO). However, the concentration in 30 % of sampling sites in the Lower Dir showed 222Rn concentrations higher than a recommended level of 11.1 Bq/L. This study evaluated the potential non-cancer risk and estimated lifetime cancer risk (ELCR) of various age groups via 222Rn consumption in groundwater. The results showed´s total annual mean exposure doses (EwTotal) values for infant of 43.7 ± 10.2, 25.2 ± 3.15, 27.0 ± 1.68 μSv/a, children 33.5 ± 7.80, 19.3 ± 2.42, 20.1 ± 1.29 μSv/a), and adults (32.3 ± 7.52, 18.6 ± 2.33, 20.0 ± 1.24 μSv/a) via groundwater intake in Lower Dir, Upper Dir, and Chitral districts, respectively. Infants showed higher vulnerability to health issues due to 222Rn contamination in groundwater. 222Rn concentrations showed a weak correlation with various studied physicochemical parameters in the groundwater.
{"title":"Radon contamination, risk evaluation, and their spatial distribution in groundwater of three selected northern districts","authors":"Said Muhammad , Rizwan Ullah , Sehrish Amin , Ashfaq Ahmad","doi":"10.1016/j.gexplo.2024.107644","DOIUrl":"10.1016/j.gexplo.2024.107644","url":null,"abstract":"<div><div>Radon (<sup>222</sup>Rn) has a ubiquitous nature in the environment and can pose serious health threats to living beings. Groundwater is the primary source of drinking and domestic uses for >3 million people in the area. The current study was conducted for investigation of groundwater for the <sup>222</sup>Rn concentration and associated health risks. For that purpose, the groundwater was examined for <sup>222</sup>Rn concentration using the RAD7 detector (Durridge Company, USA). Average concentrations of <sup>222</sup>Rn were highest at 10.8 ± 3.6 Bq/L in the Lower Dir district and lowest at 6.39 ± 0.98 Bq/L in the Upper Dir. The average concentration of <sup>222</sup>Rn was found below the threshold limit set by the US Environmental Protection Agency (USEPA) and the World Health Organization (WHO). However, the concentration in 30 % of sampling sites in the Lower Dir showed <sup>222</sup>Rn concentrations higher than a recommended level of 11.1 Bq/L. This study evaluated the potential non-cancer risk and estimated lifetime cancer risk (ELCR) of various age groups via <sup>222</sup>Rn consumption in groundwater. The results showed´s total annual mean exposure doses (EwTotal) values for infant of 43.7 ± 10.2, 25.2 ± 3.15, 27.0 ± 1.68 μSv/a, children 33.5 ± 7.80, 19.3 ± 2.42, 20.1 ± 1.29 μSv/a), and adults (32.3 ± 7.52, 18.6 ± 2.33, 20.0 ± 1.24 μSv/a) via groundwater intake in Lower Dir, Upper Dir, and Chitral districts, respectively. Infants showed higher vulnerability to health issues due to <sup>222</sup>Rn contamination in groundwater. <sup>222</sup>Rn concentrations showed a weak correlation with various studied physicochemical parameters in the groundwater.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107644"},"PeriodicalIF":3.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720926","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}
Pub Date : 2024-11-20DOI: 10.1016/j.gexplo.2024.107634
Hamid Zekri , David Cohen , Neil Rutherford , Chris Folkes , Matilda Thomas
Regolith geochemical and geophysical patterns related to underlying mineralisation may be difficult to detect in regions where the regolith is thick, transported or has developed complex layering during its mineralogical and geochemical evolution. Detection and accurate logging of geochemical and mineralogical interfaces and horizons within drill samples obtained from such regolith profiles, including the boundary between regolith and underlying bedrock can be critical for detection and interpretation of geochemical patterns. In turn, this assists in selecting zones for systematic sampling and the optimum combination of geochemical, mineralogical and geophysical analysis and data processing to enhance signals or patterns associated with mineralisation.
This study presents a multivariate data-driven approach to detecting boundaries within regolith and other profiles potentially incorporating near real-time, in-situ geochemical, mineralogical, and petrophysical data acquisition methods to aid decision-making during stratigraphic/exploration drilling campaigns. The approach is demonstrated using geochemical and mineralogical data from a drillhole at the McKinnons Au deposit in New South Wales (NSW), Australia. Embedding feature (variable) selection techniques to support vector machines and random forest approaches, followed by application of a wavelet tessellation technique encoded in Data Mosaic™ to the selected variables, delivered more detailed and refined identification of zonation and boundaries within the regolith compared with approaches using only visual core logging and geochemical assays. The method was subsequently applied to geochemical, petrophysical and spectral data acquired from two drillholes in the Delamerian Orogen of western NSW. Several subtle lithological boundaries were detected within the regolith and the interface between weathered profiles and basement rocks at different spatial scales. This included some zones displaying elevated Pb and Zn within the saprock part of the regolith profile. A critical zone above the saprock, highlighted by a high variance interval was also detected using the multivariate wavelet tessellation. This indicated shorter core sampling intervals may be needed to improve the likelihood of detecting mineralisation in this region. The methodology improves the identification of mineralised zones by enabling dynamic drilling adjustments through near real-time knowledge feedback, which also reduces costs and enhances field efficiency.
在碎屑岩较厚、被搬运或在其矿物学和地球化学演变过程中形成复杂分层的地区，可能很难探测到与底层矿化有关的碎屑岩地球化学和地球物理模式。探测和准确记录从此类碎屑岩剖面获得的钻探样本中的地球化学和矿物学界面和层位，包括碎屑岩和下伏基岩之间的边界，对于探测和解释地球化学模式至关重要。反过来，这也有助于选择系统取样区，以及地球化学、矿物学和地球物理分析与数据处理的最佳组合，以增强与矿化相关的信号或模式。本研究提出了一种多元数据驱动方法，用于检测碎屑岩和其他剖面内的边界，可能会结合近实时、原位地球化学、矿物学和岩石物理数据采集方法，以帮助地层/勘探钻探活动期间的决策。该方法利用澳大利亚新南威尔士州（NSW）麦金农金矿床钻孔的地球化学和矿物学数据进行了演示。将特征（变量）选择技术嵌入到支持向量机和随机森林方法中，然后将 Data Mosaic™ 中编码的小波分割技术应用到所选变量中，与仅使用可视岩心测井和地球化学分析的方法相比，该方法能够更详细、更精细地识别碎屑岩中的分带和边界。该方法随后被应用于从新南威尔士州西部德拉姆造山带的两个钻孔中获取的地球化学、岩石物理和光谱数据。在不同空间尺度的碎屑岩以及风化剖面与基底岩之间的界面上，发现了几处微妙的岩性边界。这包括在碎屑岩剖面的边岩部分显示出铅和锌升高的一些区域。使用多变量小波网格划分法还检测到了边岩上方的一个临界区，该临界区突出表现为一个高方差区间。这表明可能需要缩短岩芯取样间隔，以提高在该区域探测到矿化物的可能性。该方法通过近乎实时的知识反馈进行动态钻探调整，从而改进了矿化带的识别，同时还降低了成本，提高了现场效率。
{"title":"Rapid analysis of drill core data for detection of geological boundaries","authors":"Hamid Zekri , David Cohen , Neil Rutherford , Chris Folkes , Matilda Thomas","doi":"10.1016/j.gexplo.2024.107634","DOIUrl":"10.1016/j.gexplo.2024.107634","url":null,"abstract":"<div><div>Regolith geochemical and geophysical patterns related to underlying mineralisation may be difficult to detect in regions where the regolith is thick, transported or has developed complex layering during its mineralogical and geochemical evolution. Detection and accurate logging of geochemical and mineralogical interfaces and horizons within drill samples obtained from such regolith profiles, including the boundary between regolith and underlying bedrock can be critical for detection and interpretation of geochemical patterns. In turn, this assists in selecting zones for systematic sampling and the optimum combination of geochemical, mineralogical and geophysical analysis and data processing to enhance signals or patterns associated with mineralisation.</div><div>This study presents a multivariate data-driven approach to detecting boundaries within regolith and other profiles potentially incorporating near real-time, in-situ geochemical, mineralogical, and petrophysical data acquisition methods to aid decision-making during stratigraphic/exploration drilling campaigns. The approach is demonstrated using geochemical and mineralogical data from a drillhole at the McKinnons Au deposit in New South Wales (NSW), Australia. Embedding feature (variable) selection techniques to support vector machines and random forest approaches, followed by application of a wavelet tessellation technique encoded in Data Mosaic™ to the selected variables, delivered more detailed and refined identification of zonation and boundaries within the regolith compared with approaches using only visual core logging and geochemical assays. The method was subsequently applied to geochemical, petrophysical and spectral data acquired from two drillholes in the Delamerian Orogen of western NSW. Several subtle lithological boundaries were detected within the regolith and the interface between weathered profiles and basement rocks at different spatial scales. This included some zones displaying elevated Pb and Zn within the saprock part of the regolith profile. A critical zone above the saprock, highlighted by a high variance interval was also detected using the multivariate wavelet tessellation. This indicated shorter core sampling intervals may be needed to improve the likelihood of detecting mineralisation in this region. The methodology improves the identification of mineralised zones by enabling dynamic drilling adjustments through near real-time knowledge feedback, which also reduces costs and enhances field efficiency.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107634"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.gexplo.2024.107638
Anna Januszewska , Rafał Siuda , Łukasz Kruszewski
The Maramureș region in Romania is renowned for its extensive mining history and rich polymetallic mineralization. This study focuses on the Breiner mine near Băiuț (~35 km east of Baia Mare), where historical Au-Ag-Pb-Cu-Zn exploitation took place. The weathering of ore minerals has led to the formation of rich assemblages of secondary minerals (SM). The dominant SM identified are melanterite, halotrichite group minerals, jarosite, goslarite, and schwertmannite. Their crystallization is significantly influenced by low pH, humidity, groundwater supply, temperature, microorganism activity, and saturation with the particular cations and SO42−. The availability of a variety of ions contributes to the formation of a diverse range of supergene phases, including Mg, Zn, and Al sulfates. Melanterite exhibits high enrichment in Zn (>1 wt%) and, in certain instances, Cu (>2800 ppm). Halotrichite group minerals demonstrate a notable capacity for retention of >1 wt% Zn, 1700–3500 ppm As, and 1900–3500 ppm Mn. Arsenic, Pb, and Hg are mainly captured by jarosite (As >1 wt%; Pb >3300 ppm; Hg >1 ppm) and schwertmannite (As >1 wt%; Pb >500 ppm; Hg >9 ppm). Goslarite and rozenite exhibit enrichment in Ni (~1000 ppm) and Co (~700 ppm). Properties of mine waters within this site are characterized as low pH (pH 2.1–3.7) and extreme-metal concentration. Waters with the highest contamination levels are rich in As (>1500 mg/l), Zn (>9500 mg/l), Mn (>1000 mg/l), Cu (>350 mg/l), Cd (>40 mg/l), and Ni (>40 mg/l). Such high levels of dissolved contaminants are correlated with the presence of melanterite. The obtained values for toxic metals and semi-metals emphasize that these weathering zones pose a significant threat to the local environment.
{"title":"Composition and geochemistry of recently formed secondary mineral parageneses from the Breiner mine, Maramureș, Romania","authors":"Anna Januszewska , Rafał Siuda , Łukasz Kruszewski","doi":"10.1016/j.gexplo.2024.107638","DOIUrl":"10.1016/j.gexplo.2024.107638","url":null,"abstract":"<div><div>The Maramureș region in Romania is renowned for its extensive mining history and rich polymetallic mineralization. This study focuses on the Breiner mine near Băiuț (~35 km east of Baia Mare), where historical Au-Ag-Pb-Cu-Zn exploitation took place. The weathering of ore minerals has led to the formation of rich assemblages of secondary minerals (SM). The dominant SM identified are melanterite, halotrichite group minerals, jarosite, goslarite, and schwertmannite. Their crystallization is significantly influenced by low pH, humidity, groundwater supply, temperature, microorganism activity, and saturation with the particular cations and SO<sub>4</sub><sup>2−</sup>. The availability of a variety of ions contributes to the formation of a diverse range of supergene phases, including Mg, Zn, and Al sulfates. Melanterite exhibits high enrichment in Zn (>1 wt%) and, in certain instances, Cu (>2800 ppm). Halotrichite group minerals demonstrate a notable capacity for retention of >1 wt% Zn, 1700–3500 ppm As, and 1900–3500 ppm Mn. Arsenic, Pb, and Hg are mainly captured by jarosite (As >1 wt%; Pb >3300 ppm; Hg >1 ppm) and schwertmannite (As >1 wt%; Pb >500 ppm; Hg >9 ppm). Goslarite and rozenite exhibit enrichment in Ni (~1000 ppm) and Co (~700 ppm). Properties of mine waters within this site are characterized as low pH (pH 2.1–3.7) and extreme-metal concentration. Waters with the highest contamination levels are rich in As (>1500 mg/l), Zn (>9500 mg/l), Mn (>1000 mg/l), Cu (>350 mg/l), Cd (>40 mg/l), and Ni (>40 mg/l). Such high levels of dissolved contaminants are correlated with the presence of melanterite. The obtained values for toxic metals and semi-metals emphasize that these weathering zones pose a significant threat to the local environment.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107638"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719980","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}
Pub Date : 2024-11-20DOI: 10.1016/j.gexplo.2024.107637
Isabel Pérez-Martínez , Ruth Esther Villanueva-Estrada , Claudio Inguaggiato , Mario Alberto Hernández-Hernández , Giovanni Sosa-Ceballos
<div><div>The Araró-Simirao geothermal system is located in the eastern part of Cuitzeo Lake in Michoacán, Mexico. It is a liquid-dominated convective system featuring a high salinity, rapid discharge, and heat loss derived into a self-sealing process. The reservoir temperature is higher than 200 °C, associated with a fracture zone linked to the Araró-Simirao fault. Samples of thermal fluids (water and gases) were collected from springs, wells, a mud pool, and runoff water in the study area. The waters had temperatures ranging from 31 °C and 76 °C and near-neutral pH values. Three hydrogeochemical facies types were identified, Na<sup>+</sup>- Cl<sup>−</sup>, Ca<sup>2+</sup>-Na<sup>+</sup> - HCO<sub>3</sub><sup>−</sup>, and Na<sup>+</sup> -HCO<sub>3</sub><sup>−</sup>, associated with deep thermal water, groundwater, and recently infiltrated water, respectively.</div><div>According to the stable isotopes systematics, a binary mixture of thermal water and groundwater was calculated at a proportion from 61 % to 80 % of the thermal component. In the mud pool sample, the chemical composition of bubbling gas is CO<sub>2</sub>-dominated, with a mostly magmatic origin according to the Rc/Ra (5.19), CO<sub>2</sub>/<sup>3</sup>He (4.12 × 10<sup>9</sup>) ratios, and the isotopic composition of δ<sup>13</sup>C<sub>(CO2)</sub> (−8 ‰). The gases dissolved in waters are characterized by higher N<sub>2</sub> and CO<sub>2</sub> concentrations compared to the other gases, representing possible mixing processes between an end-member enriched in CO<sub>2</sub> and the chemical composition of air-saturated water. Regarding helium isotopes, the gases are the result of mixing origins between crustal, atmospheric, and mantellic helium, and 3 groups were identified: 1) high contribution of mantle helium ranging from 21 to 66 % up to (Mud pool, LS07 and LS07A) 2) high contribution of crustal helium (LSA-02, LSA-08A, Araró) ranging from 55 to 80 % and 3) high contribution of atmospheric helium of 84 % (LSA-08). The δ<sup>13</sup>C<sub>(CO2)</sub> results show a primary interaction with magmatic environments and a slightly sedimentary origin. The origin of CO<sub>2</sub>, MORB-type, as well as other gases, may be similar to that in Los Azufres. However, these gases reach the surface through different vertical paths, resulting in varying fluid compositions. In the study area, the Araró-Simirao and Huigo faults would act as zones for these gas ascents from the degassing source (magma) at depth.</div><div>According to the estimates of the magma aging model, the age of the mud pool sample is estimated to be 2.7 × 10<sup>6</sup> ± 1.2 × 10<sup>6</sup> years, which is younger than the andesitic basement rocks. Additionally, there is evidence of a more recent <sup>3</sup>He input in the sample. However, the Los Azufres geothermal system has a <sup>3</sup>He input from rocks that are even younger (1.5 × 10<sup>5</sup> years). This suggests that Los Azufres may have a more recent <su
{"title":"Origin of fluids in the Araró-Simirao geothermal system, Central Mexico","authors":"Isabel Pérez-Martínez , Ruth Esther Villanueva-Estrada , Claudio Inguaggiato , Mario Alberto Hernández-Hernández , Giovanni Sosa-Ceballos","doi":"10.1016/j.gexplo.2024.107637","DOIUrl":"10.1016/j.gexplo.2024.107637","url":null,"abstract":"<div><div>The Araró-Simirao geothermal system is located in the eastern part of Cuitzeo Lake in Michoacán, Mexico. It is a liquid-dominated convective system featuring a high salinity, rapid discharge, and heat loss derived into a self-sealing process. The reservoir temperature is higher than 200 °C, associated with a fracture zone linked to the Araró-Simirao fault. Samples of thermal fluids (water and gases) were collected from springs, wells, a mud pool, and runoff water in the study area. The waters had temperatures ranging from 31 °C and 76 °C and near-neutral pH values. Three hydrogeochemical facies types were identified, Na<sup>+</sup>- Cl<sup>−</sup>, Ca<sup>2+</sup>-Na<sup>+</sup> - HCO<sub>3</sub><sup>−</sup>, and Na<sup>+</sup> -HCO<sub>3</sub><sup>−</sup>, associated with deep thermal water, groundwater, and recently infiltrated water, respectively.</div><div>According to the stable isotopes systematics, a binary mixture of thermal water and groundwater was calculated at a proportion from 61 % to 80 % of the thermal component. In the mud pool sample, the chemical composition of bubbling gas is CO<sub>2</sub>-dominated, with a mostly magmatic origin according to the Rc/Ra (5.19), CO<sub>2</sub>/<sup>3</sup>He (4.12 × 10<sup>9</sup>) ratios, and the isotopic composition of δ<sup>13</sup>C<sub>(CO2)</sub> (−8 ‰). The gases dissolved in waters are characterized by higher N<sub>2</sub> and CO<sub>2</sub> concentrations compared to the other gases, representing possible mixing processes between an end-member enriched in CO<sub>2</sub> and the chemical composition of air-saturated water. Regarding helium isotopes, the gases are the result of mixing origins between crustal, atmospheric, and mantellic helium, and 3 groups were identified: 1) high contribution of mantle helium ranging from 21 to 66 % up to (Mud pool, LS07 and LS07A) 2) high contribution of crustal helium (LSA-02, LSA-08A, Araró) ranging from 55 to 80 % and 3) high contribution of atmospheric helium of 84 % (LSA-08). The δ<sup>13</sup>C<sub>(CO2)</sub> results show a primary interaction with magmatic environments and a slightly sedimentary origin. The origin of CO<sub>2</sub>, MORB-type, as well as other gases, may be similar to that in Los Azufres. However, these gases reach the surface through different vertical paths, resulting in varying fluid compositions. In the study area, the Araró-Simirao and Huigo faults would act as zones for these gas ascents from the degassing source (magma) at depth.</div><div>According to the estimates of the magma aging model, the age of the mud pool sample is estimated to be 2.7 × 10<sup>6</sup> ± 1.2 × 10<sup>6</sup> years, which is younger than the andesitic basement rocks. Additionally, there is evidence of a more recent <sup>3</sup>He input in the sample. However, the Los Azufres geothermal system has a <sup>3</sup>He input from rocks that are even younger (1.5 × 10<sup>5</sup> years). This suggests that Los Azufres may have a more recent <su","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107637"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.gexplo.2024.107639
Bijan Roshanravan , Oliver P. Kreuzer , Amanda Buckingham
Here we describe the application of a novel hybrid multi-criteria decision-making (MCDM) approach termed “Best-Worst-Method-Measurement of Alternatives and Ranking according to COmpromise Solution” (BWM-MARCOS) to mineral potential modelling (MPM). The newly proposed BWM-MARCOS technique combines two mathematical frameworks in which the BWM approach is utilised to weight decision criteria (i.e., predictor maps) whilst the MARCOS approach is applied to rank alternatives. A BWM-MARCOS model of orogenic gold mineral systems in the well-endowed Granites-Tanami Orogen (GTO) in Australia's Northern Territory was generated utilising the same study area and set of competent spatial proxies as previously developed and described by Roshanravan et al. (2020), facilitating the benchmarking of the new results against those obtained from previous models. We found the BWM-MARCOS approach to MPM performed better than any of the knowledge-driven (i.e., fuzzy inference system), continuous (i.e., data-driven index overlay, geometric average and fuzzy gamma) and data-driven (i.e., feed-forward deep neural network and ‘original’ random forest) mineral prospectivity models previously developed for the GTO by Roshanravan et al. (2020, 2023b). To further constrain the BWM-MARCOS outputs, the modeled gold potential zones were delimited utilising a concentration-area fractal approach. The areas covered by the prioritised 1st order (top priority) and 2nd order (high priority) targets represent significant reductions of the search space (i.e., >303 times or two orders of magnitude, and >93 times or one order of magnitude, respectively). Any order of magnitude, or greater, reduction of the search space, as achieved in this study, can be considered a hallmark of a well-performing, practically useful targeting approach.
{"title":"BWM-MARCOS: A new hybrid MCDM approach for mineral potential modelling","authors":"Bijan Roshanravan , Oliver P. Kreuzer , Amanda Buckingham","doi":"10.1016/j.gexplo.2024.107639","DOIUrl":"10.1016/j.gexplo.2024.107639","url":null,"abstract":"<div><div>Here we describe the application of a novel hybrid multi-criteria decision-making (MCDM) approach termed “Best-Worst-Method-Measurement of Alternatives and Ranking according to COmpromise Solution” (BWM-MARCOS) to mineral potential modelling (MPM). The newly proposed BWM-MARCOS technique combines two mathematical frameworks in which the BWM approach is utilised to weight decision criteria (i.e., predictor maps) whilst the MARCOS approach is applied to rank alternatives. A BWM-MARCOS model of orogenic gold mineral systems in the well-endowed Granites-Tanami Orogen (GTO) in Australia's Northern Territory was generated utilising the same study area and set of competent spatial proxies as previously developed and described by Roshanravan et al. (2020), facilitating the benchmarking of the new results against those obtained from previous models. We found the BWM-MARCOS approach to MPM performed better than any of the knowledge-driven (i.e., fuzzy inference system), continuous (i.e., data-driven index overlay, geometric average and fuzzy gamma) and data-driven (i.e., feed-forward deep neural network and ‘original’ random forest) mineral prospectivity models previously developed for the GTO by Roshanravan et al. (2020, 2023b). To further constrain the BWM-MARCOS outputs, the modeled gold potential zones were delimited utilising a concentration-area fractal approach. The areas covered by the prioritised 1st order (top priority) and 2nd order (high priority) targets represent significant reductions of the search space (i.e., >303 times or two orders of magnitude, and >93 times or one order of magnitude, respectively). Any order of magnitude, or greater, reduction of the search space, as achieved in this study, can be considered a hallmark of a well-performing, practically useful targeting approach.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107639"},"PeriodicalIF":3.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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