Pub Date : 2025-05-05DOI: 10.1016/j.oreoa.2025.100102
Ema Abraham , Moses Emetere
The Plateau-Bauchi Basement Complex in northern Nigeria is a geologically diverse region with significant mineral potential. This study employs an integrated geophysical approach to map the structural framework and mineralization controls within this economically vital region. High-resolution aeromagnetic data were processed using a comprehensive suite of magnetic analysis techniques. The analytical toolkit included Source Parameter Imaging (SPI), Phase Symmetry (PS), Analytic Signal (AS), Tilt Derivative analysis, Butterworth bandpass filtering, 3D magnetic anomaly inversion, and Euler deconvolution. Our results reveal an intricate network of faults, fractures, and intrusive bodies that govern mineralization patterns across the study area. Prominent structural trends (NW-SE, NE-SW, E-W, and N-S) and estimated depths to magnetic sources ranging from near-surface (<420 m) to deeper structures (up to 1330 m) have been delineated. Integration of the geophysical techniques allows for the delineation of high-susceptibility zones corresponding to potential mineral-rich deposits. Strong correlations between geophysical anomalies and known occurrences of economically important minerals, including tin, columbite, kaolin, niobium, and rare earth elements such as tourmaline are observed. Complex fault intersections and intrusive features, particularly in the Kakkek, Durbi, Durr, and Barkin Ladi regions, create favorable conditions for mineral accumulation. This study provides crucial insights into the subsurface architecture of the Plateau-Bauchi basement complex and its relationship to mineralization processes. Our findings establish a robust framework for guiding future exploration efforts and contribute significantly to the understanding of mineral deposit formation in complex geological terrains.
{"title":"Magnetic anomaly investigation for mineral potential assessment in the Plateau-Bauchi basement complex, Northern Nigeria","authors":"Ema Abraham , Moses Emetere","doi":"10.1016/j.oreoa.2025.100102","DOIUrl":"10.1016/j.oreoa.2025.100102","url":null,"abstract":"<div><div>The Plateau-Bauchi Basement Complex in northern Nigeria is a geologically diverse region with significant mineral potential. This study employs an integrated geophysical approach to map the structural framework and mineralization controls within this economically vital region. High-resolution aeromagnetic data were processed using a comprehensive suite of magnetic analysis techniques. The analytical toolkit included Source Parameter Imaging (SPI), Phase Symmetry (PS), Analytic Signal (AS), Tilt Derivative analysis, Butterworth bandpass filtering, 3D magnetic anomaly inversion, and Euler deconvolution. Our results reveal an intricate network of faults, fractures, and intrusive bodies that govern mineralization patterns across the study area. Prominent structural trends (NW-SE, NE-SW, E-W, and N-S) and estimated depths to magnetic sources ranging from near-surface (<420 m) to deeper structures (up to 1330 m) have been delineated. Integration of the geophysical techniques allows for the delineation of high-susceptibility zones corresponding to potential mineral-rich deposits. Strong correlations between geophysical anomalies and known occurrences of economically important minerals, including tin, columbite, kaolin, niobium, and rare earth elements such as tourmaline are observed. Complex fault intersections and intrusive features, particularly in the Kakkek, Durbi, Durr, and Barkin Ladi regions, create favorable conditions for mineral accumulation. This study provides crucial insights into the subsurface architecture of the Plateau-Bauchi basement complex and its relationship to mineralization processes. Our findings establish a robust framework for guiding future exploration efforts and contribute significantly to the understanding of mineral deposit formation in complex geological terrains.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"19 ","pages":"Article 100102"},"PeriodicalIF":0.0,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Late Archean rare metal (Nb-Ta-Li-Be) bearing granitic pegmatites of the Nagamangala Schist Belt, Dharwar Craton, India, represent an important geological setting for understanding the mineralogical and geochemical evolution of Lithium-Cesium-Tantalum (LCT) pegmatites. This study provides detailed insights into the mineral chemistry of uraninite and zircon, using Back Scattered Electron (BSE) imaging and quantitative Electron Probe Micro Analysis (EPMA), to characterize their composition, formation history, and evolutionary trends. Subsurface samples of pegmatites from the Marlagalla area reveal the presence of euhedral to anhedral Th-rich uraninite along with unusually high hafnium (Hf) content in the associated zircon-an aspect reported first time from these pegmatites. Uraninite grains are found partially or fully enclosed by phases such as garnet, microlite [(Ca,Na)2Ta2O6(O,OH,F)], tapiolite [(Fe,Mn)(Ta,Nb)2O], zircon and apatite in the studied samples. Uraninite grains exhibit significant compositional variations, with UO2 ranging from 64.74 to 70.92 wt %, high ThO2 concentrations (up to 10.85 wt %), and PbO content between 23.01 and 25.37 wt %. The rare earth element (REE) content is notably low (RE2O3: 0.15–0.89 wt %), and SiO2 is nearly absent (<0.01 to 0.29 wt %). Chemical formula calculations indicate a U4+ range of 0.227–0.345 and U6+ between 0.301–0.340, suggesting significant auto-oxidation-a hallmark of ancient uraninites. Furthermore, EPMA-based U-Th-Pb chemical age dating of the uraninite suggests a minimum formation age of approximately 2335 ± 54 Ma, making it the oldest reported uraninite in pegmatite from Indian subcontinent.
The associated zircon grains display exceptionally high HfO2 content (9.94–20.49 %), coupled with ZrO2 (45.56–58.89 %) and SiO2 (27.59–30.56 %), categorizing them as hafnian zircons. Their elevated radioactive element content and close association with uranothorite, alongside the high Th content in uraninite, indicate progressive magmatic fractionation. This is further supported by geochemical trends such as the Zr/Hf vs. Hf in zircon and UO2/ThO2 vs. ThO2 in uraninite. The U6+/U4+ ratio close to unity suggests auto-oxidation as the dominant mechanism, reinforced by the high PbO content in these uraninites.
These findings provide crucial insights into the Late Archean Algoman orogeny, a global event marked by extensive granitic plutonism. The Marlagalla pegmatites share key mineralogical and geochemical similarities with other Algoman-related pegmatites, suggesting a possible genetic link. Furthermore, the evolved nature of these pegmatites, in relation to the adjacent Allapatna granite, underscores their complex magmatic history and potential economic significance
{"title":"Late Archean Rare Metal (Nb-Ta-Li-Be) bearing Granitic Pegmatite (LCT) in Nagamangala Schist Belt, Dharwar Craton, India: Insights from Uraninite and Zircon mineral chemistry","authors":"Chanchal Sarbajna , Sudhiranjan Swain , V.R. Akhila , K.L. Mundra , Dheeraj Pande","doi":"10.1016/j.oreoa.2025.100100","DOIUrl":"10.1016/j.oreoa.2025.100100","url":null,"abstract":"<div><div>The Late Archean rare metal (Nb-Ta-Li-Be) bearing granitic pegmatites of the Nagamangala Schist Belt, Dharwar Craton, India, represent an important geological setting for understanding the mineralogical and geochemical evolution of Lithium-Cesium-Tantalum (LCT) pegmatites. This study provides detailed insights into the mineral chemistry of uraninite and zircon, using Back Scattered Electron (BSE) imaging and quantitative Electron Probe Micro Analysis (EPMA), to characterize their composition, formation history, and evolutionary trends. Subsurface samples of pegmatites from the Marlagalla area reveal the presence of euhedral to anhedral Th-rich uraninite along with unusually high hafnium (Hf) content in the associated zircon-an aspect reported first time from these pegmatites. Uraninite grains are found partially or fully enclosed by phases such as garnet, microlite [(Ca,Na)<sub>2</sub>Ta<sub>2</sub>O<sub>6</sub>(O,OH,F)], tapiolite [(Fe,Mn)(Ta,Nb)<sub>2</sub>O], zircon and apatite in the studied samples. Uraninite grains exhibit significant compositional variations, with UO<sub>2</sub> ranging from 64.74 to 70.92 wt %, high ThO<sub>2</sub> concentrations (up to 10.85 wt %), and PbO content between 23.01 and 25.37 wt %. The rare earth element (REE) content is notably low (RE<sub>2</sub>O<sub>3</sub>: 0.15–0.89 wt %), and SiO<sub>2</sub> is nearly absent (<0.01 to 0.29 wt %). Chemical formula calculations indicate a U<sup>4+</sup> range of 0.227–0.345 and U<sup>6+</sup> between 0.301–0.340, suggesting significant auto-oxidation-a hallmark of ancient uraninites. Furthermore, EPMA-based U-Th-Pb chemical age dating of the uraninite suggests a minimum formation age of approximately 2335 ± 54 Ma, making it the oldest reported uraninite in pegmatite from Indian subcontinent.</div><div>The associated zircon grains display exceptionally high HfO<sub>2</sub> content (9.94–20.49 %), coupled with ZrO<sub>2</sub> (45.56–58.89 %) and SiO<sub>2</sub> (27.59–30.56 %), categorizing them as hafnian zircons. Their elevated radioactive element content and close association with uranothorite, alongside the high Th content in uraninite, indicate progressive magmatic fractionation. This is further supported by geochemical trends such as the Zr/Hf vs. Hf in zircon and UO<sub>2</sub>/ThO<sub>2</sub> vs. ThO<sub>2</sub> in uraninite. The U<sup>6+</sup>/U<sup>4+</sup> ratio close to unity suggests auto-oxidation as the dominant mechanism, reinforced by the high PbO content in these uraninites.</div><div>These findings provide crucial insights into the Late Archean Algoman orogeny, a global event marked by extensive granitic plutonism. The Marlagalla pegmatites share key mineralogical and geochemical similarities with other Algoman-related pegmatites, suggesting a possible genetic link. Furthermore, the evolved nature of these pegmatites, in relation to the adjacent Allapatna granite, underscores their complex magmatic history and potential economic significance","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"19 ","pages":"Article 100100"},"PeriodicalIF":0.0,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100068
Andreas Michael, Abdelhakim Khouissat
Reservoir depletion can be consequential to wellbore integrity after a blowout, especially offshore. A prolonged post-blowout discharge extends reservoir depletion. “Underground blowouts” (tensile-fracture initiations) occurring after well capping, or shear-driven slow slippage of naturally-occurring pre-existing faults (PEFs) in the near-well vicinity, can compromise post-blowout wellbore integrity. Upward propagation of the initiated tensile fractures may trigger seafloor broaching by reservoir hydrocarbons.
This study examines reservoir depletion analytically, evaluating associated geomechanical implications on the in-situ reservoir conditions and assessing the likelihood of tensile-fracture initiation (oriented longitudinally or transversely-to-the-wellbore) during post-blowout-well-capping operations, in addition to shear-driven slow slippage along PEFs in the near-well vicinity. A set of calculational procedures and thinking sequences are presented, necessary for encompassing the primary effects of post-blowout reservoir depletion on the in-situ stress state and the limits of tensile and shear failures that could aid in the appropriate blowout-contingency decision-making.
Our novel, physics-based scheme (analytical-coupling approach) is applied to parameters from the MC 252–1 “Macondo Well” blowout from April 20, 2010 and the targeted M56 oil reservoir in deepwater Gulf of Mexico (GoM). The reservoir rock is modeled as a porous-permeable medium, considering fluid infiltration to-and-from the pressurized wellbore. The likelihood of an underground blowout correlates with the shut-in wellbore pressure buildup, after successful well capping.
Elevated reservoir depletion via higher post-blowout-discharge flowrates and longer post-blowout-discharge periods (in terms of time duration) are shown to reduce the shut-in wellbore pressure buildup against time following well capping. The “critical discharge flowrate,” an established predictive indicator for underground blowouts following shut-in of an installed subsea-capping stack (SCS) is employed, using data from the post-blowout-discharge period, suggesting underground blowouts to be highly-unlikely for the set of parameters assessed. Finally, the Mohr-Coulomb criterion indicates that shear-driven slow slippage along PEFs in the near-well vicinity is also unlikely, considering the Macondo Well's bottomhole-wellbore-pressure history in the aftermath of the blowout.
{"title":"Coupling reservoir depletion and geomechanics to assess risks during post-blowout well capping: Case study on Macondo","authors":"Andreas Michael, Abdelhakim Khouissat","doi":"10.1016/j.oreoa.2024.100068","DOIUrl":"10.1016/j.oreoa.2024.100068","url":null,"abstract":"<div><div>Reservoir depletion can be consequential to wellbore integrity after a blowout, especially offshore. A prolonged post-blowout discharge extends reservoir depletion. “Underground blowouts” (tensile-fracture initiations) occurring after well capping, or shear-driven slow slippage of naturally-occurring pre-existing faults (PEFs) in the near-well vicinity, can compromise post-blowout wellbore integrity. Upward propagation of the initiated tensile fractures may trigger seafloor broaching by reservoir hydrocarbons.</div><div>This study examines reservoir depletion analytically, evaluating associated geomechanical implications on the <em>in-situ</em> reservoir conditions and assessing the likelihood of tensile-fracture initiation (oriented longitudinally or transversely-to-the-wellbore) during post-blowout-well-capping operations, in addition to shear-driven slow slippage along PEFs in the near-well vicinity. A set of calculational procedures and thinking sequences are presented, necessary for encompassing the primary effects of post-blowout reservoir depletion on the <em>in-situ</em> stress state and the limits of tensile and shear failures that could aid in the appropriate blowout-contingency decision-making.</div><div>Our novel, physics-based scheme (analytical-coupling approach) is applied to parameters from the MC 252–1 “Macondo Well” blowout from April 20, 2010 and the targeted M56 oil reservoir in deepwater Gulf of Mexico (GoM). The reservoir rock is modeled as a porous-permeable medium, considering fluid infiltration to-and-from the pressurized wellbore. The likelihood of an underground blowout correlates with the shut-in wellbore pressure buildup, after successful well capping.</div><div>Elevated reservoir depletion via higher post-blowout-discharge flowrates and longer post-blowout-discharge periods (in terms of time duration) are shown to reduce the shut-in wellbore pressure buildup against time following well capping. The “critical discharge flowrate,” an established predictive indicator for underground blowouts following shut-in of an installed subsea-capping stack (SCS) is employed, using data from the post-blowout-discharge period, suggesting underground blowouts to be highly-unlikely for the set of parameters assessed. Finally, the Mohr-Coulomb criterion indicates that shear-driven slow slippage along PEFs in the near-well vicinity is also unlikely, considering the Macondo Well's bottomhole-wellbore-pressure history in the aftermath of the blowout.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100068"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100071
Emmanuel Daanoba Sunkari , Arnold Nuru Gan , Etornam Bani Fiadonu
The Damang Gold Mine in southwestern Ghana sits on two kinds of mineralization: the Tarkwaian paleoplacer and a hydrothermal type found within the Tarkwaian Group's meta-sedimentary rocks. Geochemical vectors related to the hydrothermal gold mineralization in the area are not well known. Therefore, this research was conducted to identify pathfinders for hydrothermal gold mineralization in the Damang area. A total of fifty (50) rock samples were collected from three diamond drill holes focusing on mineralized zones of the holes. The mineralogy of the host rocks was established using petrographic studies of twelve (12) selected representative drill core samples. Multi-element geochemical analysis of the host rocks (n = 50) involving Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) technique was conducted to quantify the trace element concentrations in the host rocks. The multi-element geochemical data was analyzed using multivariate statistics. The petrographic studies showed the abundance of quartz, biotite, pyrite, pyrrhotite, sericite, and minor amounts of feldspars (plagioclase and orthoclase). Al, Mg, Fe, and Ca dominated the geochemical data. The highest Au concentrations were found in Birimian quartz veins and the intrusive lithologies compared to the other lithologies in the region. Most of the data failed the Shapiro-Wilk and Kolmogorov-Smirnov tests. The deviations from normality were shown graphically by Q-Q plots. The centered log-ratio transformation was used to correct this, and the data tested again for normality. Spearman rank correlation showed a positive correlation between Te, Bi, U, Ba, Ag, and Au. When hierarchical cluster analysis was run, three clusters emerged with Au in the same cluster with Te, Ag, and Bi. Factor analysis served as a confirmatory test with Au in the same factor with Bi, Ag, and Te. Datamine Studio RM was used to create drillhole logs showing the anomalies of the three elements and Au with different lithologies downhole, which showed a similitude in the abnormal occurrences. Therefore, hydrothermal gold mineralization in the Damang area is related to Bi-Te-Ag-Au multi-element association.
位于加纳西南部的达芒金矿有两种矿化类型：塔克韦安古生界和塔克韦安群元沉积岩中的热液型。与该地区热液金矿化有关的地球化学矢量并不为人所知。因此，本研究旨在确定达芒地区热液金矿化的探路者。总共从三个金刚石钻孔中采集了五十（50）个岩石样本，重点放在钻孔的矿化区。通过对十二（12）个具有代表性的钻孔岩芯样本进行岩相学研究，确定了主岩的矿物学特征。采用电感耦合等离子体质谱仪 (ICP-MS) 技术对主岩（n = 50）进行了多元素地球化学分析，以量化主岩中的微量元素浓度。多元素地球化学数据采用多元统计方法进行分析。岩相学研究显示了丰富的石英、生物黄铁矿、黄铁矿、黄铁矿、绢云母和少量长石（斜长石和正长石）。地球化学数据以铝、镁、铁和钙为主。与该地区的其他岩性相比，桦木石英脉和侵入岩性中的金含量最高。大多数数据未能通过 Shapiro-Wilk 和 Kolmogorov-Smirnov 检验。偏离正态的情况通过 Q-Q 图显示出来。采用居中对数比率转换来纠正这种偏差，并再次对数据进行正态性检验。斯皮尔曼等级相关性显示 Te、Bi、U、Ba、Ag 和 Au 之间存在正相关。在进行分层聚类分析时，出现了三个聚类，其中 Au 与 Te、Ag 和 Bi 属于同一聚类。因子分析作为一种确证检验，Au 与 Bi、Ag 和 Te 属于同一因子。使用 Datamine Studio RM 制作的钻孔记录显示了三种元素和 Au 在井下不同岩性中的异常现象，显示了异常现象的相似性。因此，达芒地区的热液金矿化与 Bi-Te-Ag-Au 多元素关联有关。
{"title":"Geochemical vectors for targeting hydrothermal gold mineralization in the Damang area, southwestern Ghana: Constraints from petrography, multi-element geochemistry and multivariate statistical analysis","authors":"Emmanuel Daanoba Sunkari , Arnold Nuru Gan , Etornam Bani Fiadonu","doi":"10.1016/j.oreoa.2024.100071","DOIUrl":"10.1016/j.oreoa.2024.100071","url":null,"abstract":"<div><div>The Damang Gold Mine in southwestern Ghana sits on two kinds of mineralization: the Tarkwaian paleoplacer and a hydrothermal type found within the Tarkwaian Group's meta-sedimentary rocks. Geochemical vectors related to the hydrothermal gold mineralization in the area are not well known. Therefore, this research was conducted to identify pathfinders for hydrothermal gold mineralization in the Damang area. A total of fifty (50) rock samples were collected from three diamond drill holes focusing on mineralized zones of the holes. The mineralogy of the host rocks was established using petrographic studies of twelve (12) selected representative drill core samples. Multi-element geochemical analysis of the host rocks (<em>n</em> = 50) involving Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) technique was conducted to quantify the trace element concentrations in the host rocks. The multi-element geochemical data was analyzed using multivariate statistics. The petrographic studies showed the abundance of quartz, biotite, pyrite, pyrrhotite, sericite, and minor amounts of feldspars (plagioclase and orthoclase). Al, Mg, Fe, and Ca dominated the geochemical data. The highest Au concentrations were found in Birimian quartz veins and the intrusive lithologies compared to the other lithologies in the region. Most of the data failed the Shapiro-Wilk and Kolmogorov-Smirnov tests. The deviations from normality were shown graphically by Q-Q plots. The centered log-ratio transformation was used to correct this, and the data tested again for normality. Spearman rank correlation showed a positive correlation between Te, Bi, U, Ba, Ag, and Au. When hierarchical cluster analysis was run, three clusters emerged with Au in the same cluster with Te, Ag, and Bi. Factor analysis served as a confirmatory test with Au in the same factor with Bi, Ag, and Te. Datamine Studio RM was used to create drillhole logs showing the anomalies of the three elements and Au with different lithologies downhole, which showed a similitude in the abnormal occurrences. Therefore, hydrothermal gold mineralization in the Damang area is related to Bi-Te-Ag-Au multi-element association.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100071"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100072
Chunyu Xiang , Huxuan Xiao , Fakun He , Zhanpeng Dai , Wenbin Huang , Bowei Zhu , Shibin Liu
The extensive accumulation of tailings can potentially cause heavy metal contamination in the surrounding farmland soil. Accurately predicting the spatial distribution of heavy metals in farmland soil is crucial for assessing the potential environmental hazards of tailings.This study focuses on the spatial distribution and the quantitative prediction of heavy metals (chromium (Cr), vanadium (V), and copper (Cu)) in soils surrounding mine tailings using advanced spectral data analysis and multiple prediction models. The original hyperspectral reflectance data were processed using first-order differential (FD), second-order differential (SD), reciprocal logarithmic (LR), and continuum removal (CR) transformations to highlight the positions of characteristic bands. Multiple linear regression (MLR), stepwise linear regression (SLR), partial least squares regression (PLSR), random forest (RF), and back propagation artificial neural network (BP-ANN) models were used to establish inversion models for Cr, V, and Cu based on bands with high correlation coefficients. The performance of the inversion models was evaluated using the coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and residual predictive deviation (RPD). The results indicate that the raw hyperspectral data from the measured soil exhibit a weak response to heavy metal content in the study area. However, applying FD, SD, and CR transformations significantly enhances the sensitivity of soil spectral data to heavy metal concentrations, facilitating subsequent modeling. Among these, the SD transformation is particularly beneficial for modeling the Cr and Cu elements in the soil. For the V element, the FD transformation yields data that are more suitable for modeling. Regarding the inversion models based on the measured spectral data, the BP-ANN model exhibited the best predictive performance. Specifically, when combined with SD spectral data, the BP-ANN achieved the highest predictive accuracy for Cu content (R² = 0.85, RPD = 2.12). The RF model demonstrated the next best performance, with its optimal inversion model also utilizing SD spectral data for predicting Cu content (R² = 0.76, RPD = 1.90). On the other hand, the MLR model exhibited the poorest performance and is unsuitable for predicting heavy metal content in the region using the measured spectral data. This study highlights the potential of spectral data in environmental monitoring and provides a technical reference for the inversion assessment and regulation of heavy metals in farmlands surrounding tailing sites.
{"title":"Prediction of soil heavy metal content around mine tailings using multiple methods combined with transformed hyperspectral reflectance data","authors":"Chunyu Xiang , Huxuan Xiao , Fakun He , Zhanpeng Dai , Wenbin Huang , Bowei Zhu , Shibin Liu","doi":"10.1016/j.oreoa.2024.100072","DOIUrl":"10.1016/j.oreoa.2024.100072","url":null,"abstract":"<div><div>The extensive accumulation of tailings can potentially cause heavy metal contamination in the surrounding farmland soil. Accurately predicting the spatial distribution of heavy metals in farmland soil is crucial for assessing the potential environmental hazards of tailings.This study focuses on the spatial distribution and the quantitative prediction of heavy metals (chromium (Cr), vanadium (V), and copper (Cu)) in soils surrounding mine tailings using advanced spectral data analysis and multiple prediction models. The original hyperspectral reflectance data were processed using first-order differential (FD), second-order differential (SD), reciprocal logarithmic (LR), and continuum removal (CR) transformations to highlight the positions of characteristic bands. Multiple linear regression (MLR), stepwise linear regression (SLR), partial least squares regression (PLSR), random forest (RF), and back propagation artificial neural network (BP-ANN) models were used to establish inversion models for Cr, V, and Cu based on bands with high correlation coefficients. The performance of the inversion models was evaluated using the coefficient of determination (<em>R<sup>2</sup></em>), root mean square error (<em>RMSE</em>), mean absolute error <em>(MAE</em>), and residual predictive deviation (<em>RPD</em>). The results indicate that the raw hyperspectral data from the measured soil exhibit a weak response to heavy metal content in the study area. However, applying FD, SD, and CR transformations significantly enhances the sensitivity of soil spectral data to heavy metal concentrations, facilitating subsequent modeling. Among these, the SD transformation is particularly beneficial for modeling the Cr and Cu elements in the soil. For the V element, the FD transformation yields data that are more suitable for modeling. Regarding the inversion models based on the measured spectral data, the BP-ANN model exhibited the best predictive performance. Specifically, when combined with SD spectral data, the BP-ANN achieved the highest predictive accuracy for Cu content (<em>R²</em> = 0.85, <em>RPD</em> = 2.12). The RF model demonstrated the next best performance, with its optimal inversion model also utilizing SD spectral data for predicting Cu content (<em>R² = 0.76, RPD</em> = 1.90). On the other hand, the MLR model exhibited the poorest performance and is unsuitable for predicting heavy metal content in the region using the measured spectral data. This study highlights the potential of spectral data in environmental monitoring and provides a technical reference for the inversion assessment and regulation of heavy metals in farmlands surrounding tailing sites.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100072"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Erratum to “Geology and petrography of the volcanic rocks in the Yakhab area, central Iran” [Ore and Energy Resource Geology (2021)100016]","authors":"Kaveh Pazand , Asghar Ghasemi Bersiani , Hassan Mohammadnezhad","doi":"10.1016/j.oreoa.2024.100070","DOIUrl":"10.1016/j.oreoa.2024.100070","url":null,"abstract":"","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100070"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100073
Hadi Veysi , Saeid Jamshidi Taghabi , Meysam Babaiy , Mehdi Tafazoli
In the case of ore deposits that are formed in marine environments, including kuroko deposits, the effect of paleo-sedimentary environment parameters and microfacies changes is very important, but it is often neglected in economic geological research. These factors determine the dispersion and concentration of ore horizons in an ore deposit area, and recognition them leads us to the localization of high concentration ore horizons.
In this regard, lead and barite ore deposit area in the southeastern of Tafresh city (the border of Markazi and Qom provinces, Iran) was investigated. This ore deposit is of the kuroko type and is of the early to middle Eocene epoch (Ypresian-Lutetian ages) and was formed in a relatively deep ancient carbonate ramp. Investigating the concentration of different minerals and ore minerals in the mentioned ore deposit area using by remote sensing techniques indicates that the distribution of minerals and ore minerals is non-uniform with a noteworthy correlation unto the carbonate ramp microfacies in the southeastern of Tafresh. The scrutiny of microfacies characteristics and paleo-sedimentary environment showed that the distance from hydrothermal smokers, the action of different seawaves, sedimentological changes, structural features and initial morphology of microfacies have a remarkable impressiveness in the dispersion of ore reserves and the formation of horizons with a high concentration of ore.
{"title":"Lead and Barium strata-bound deposits in eocene carbonate ramps of Iran: Implications for the influence of sedimentary environment characteristics on the distribution of Ore reserves","authors":"Hadi Veysi , Saeid Jamshidi Taghabi , Meysam Babaiy , Mehdi Tafazoli","doi":"10.1016/j.oreoa.2024.100073","DOIUrl":"10.1016/j.oreoa.2024.100073","url":null,"abstract":"<div><div>In the case of ore deposits that are formed in marine environments, including kuroko deposits, the effect of paleo-sedimentary environment parameters and microfacies changes is very important, but it is often neglected in economic geological research. These factors determine the dispersion and concentration of ore horizons in an ore deposit area, and recognition them leads us to the localization of high concentration ore horizons.</div><div>In this regard, lead and barite ore deposit area in the southeastern of Tafresh city (the border of Markazi and Qom provinces, Iran) was investigated. This ore deposit is of the kuroko type and is of the early to middle Eocene epoch (Ypresian-Lutetian ages) and was formed in a relatively deep ancient carbonate ramp. Investigating the concentration of different minerals and ore minerals in the mentioned ore deposit area using by remote sensing techniques indicates that the distribution of minerals and ore minerals is non-uniform with a noteworthy correlation unto the carbonate ramp microfacies in the southeastern of Tafresh. The scrutiny of microfacies characteristics and paleo-sedimentary environment showed that the distance from hydrothermal smokers, the action of different seawaves, sedimentological changes, structural features and initial morphology of microfacies have a remarkable impressiveness in the dispersion of ore reserves and the formation of horizons with a high concentration of ore.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100073"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100069
Samuel Obomheile Salufu , Kesyton Oyamenda Ozegin , Charles Chibueze Ugbor , Sunday O. Isehunwa , Emmanuel O. Salufu , Daniel Osezua Aikhuele
<div><div>The study of geologic heterogeneities (the quality of reservoir rock according to its spatial variation in properties such as grain size, mineralogy, organic content, fossil content, and natural fracture) and their impact on recovery factors, optimization, and performance of injection fluids in concurrent development (production of both oil and gas at the same time) of oil rim reservoirs (reservoirs with a thin oil column that is overlain with a large gas cap) has become necessary to explore the role of geological and biostratigraphical heterogeneity in optimizing hydrocarbon recovery from oil rim reservoirs in the Niger Delta using integrated seismic, petrophysical, and core data. This is to achieve optimum hydrocarbon recovery instead of relying only on development strategies, which is usually the practice and thus fails. Petrel and Eclipse software were used to simulate the static and dynamic models, respectively, for three oil rim reservoirs, using data (seismic, petrophysical, core, and reservoir data) from a green field in the Niger Delta, Nigeria, for concurrent development under the natural depletion (base case), surfactant enhanced-water-alternating-gas (SeWAG), and water-alternating-gas (WAG) injection options. In each option, two scenarios of injection well positions were simulated: gas-oil contact (GOC) and oil-water contact (OWC). Geological studies showed that Reservoir 1 is a heterolith facies of lower-shoreface deposits with traces of Ophiomorpha burrows, Reservoir 2 is a channel facies of lower shoreface deposits with Ophiomorpha burrows, and Reservoir 3 is a heterolith facies of upper shoreface without vertical burrows. When SeWAG of ratio 1:4:2 was injected at OWC, the highest oil recovery factor was observed compared to other options, and injection at GOC gave the highest gas recovery factor. Permeability anisotropy (Kv/Kh) for reservoirs 1 and 2, with Ophiomorpha burrows being considered, was 0.32 and 0.34, respectively. High recovery factors for both oil and gas were recorded. However, the model of the same reservoir without Ophiomorpha burrows gave reduced values of Kv/Kh of 0.12 and 0.15, respectively, with reduced recovery factors. Reservoir 3, which doesn't have burrows in the initial model, has a Kv/Kh value of 0.11 with low recovery factors in various development cases. However, when Ophiomorpha burrows were integrated into the model, Kv/Kh was 0.31, and the recovery factors increased significantly. The study has shown that geological and biostratigraphical interactions induce Kv/Kh. It has a significant optimization impact on recovery factors in concurrent development and enhances vertical sweep efficiency in EOR (Enhanced Oil Recovery). The study further shows that <em>Ophiomorpha</em> burrows improve the geologic heterogeneity quality of a reservoir (permeability anisotropy) by enhancing the injection fluid to get into micro- and macropore spaces for efficient sweeping of oil and gas into the development w
{"title":"Geological and biostratigraphical factors in hydrocarbon recovery optimization using integrated seismic, petrophysical, and core data, Niger Delta","authors":"Samuel Obomheile Salufu , Kesyton Oyamenda Ozegin , Charles Chibueze Ugbor , Sunday O. Isehunwa , Emmanuel O. Salufu , Daniel Osezua Aikhuele","doi":"10.1016/j.oreoa.2024.100069","DOIUrl":"10.1016/j.oreoa.2024.100069","url":null,"abstract":"<div><div>The study of geologic heterogeneities (the quality of reservoir rock according to its spatial variation in properties such as grain size, mineralogy, organic content, fossil content, and natural fracture) and their impact on recovery factors, optimization, and performance of injection fluids in concurrent development (production of both oil and gas at the same time) of oil rim reservoirs (reservoirs with a thin oil column that is overlain with a large gas cap) has become necessary to explore the role of geological and biostratigraphical heterogeneity in optimizing hydrocarbon recovery from oil rim reservoirs in the Niger Delta using integrated seismic, petrophysical, and core data. This is to achieve optimum hydrocarbon recovery instead of relying only on development strategies, which is usually the practice and thus fails. Petrel and Eclipse software were used to simulate the static and dynamic models, respectively, for three oil rim reservoirs, using data (seismic, petrophysical, core, and reservoir data) from a green field in the Niger Delta, Nigeria, for concurrent development under the natural depletion (base case), surfactant enhanced-water-alternating-gas (SeWAG), and water-alternating-gas (WAG) injection options. In each option, two scenarios of injection well positions were simulated: gas-oil contact (GOC) and oil-water contact (OWC). Geological studies showed that Reservoir 1 is a heterolith facies of lower-shoreface deposits with traces of Ophiomorpha burrows, Reservoir 2 is a channel facies of lower shoreface deposits with Ophiomorpha burrows, and Reservoir 3 is a heterolith facies of upper shoreface without vertical burrows. When SeWAG of ratio 1:4:2 was injected at OWC, the highest oil recovery factor was observed compared to other options, and injection at GOC gave the highest gas recovery factor. Permeability anisotropy (Kv/Kh) for reservoirs 1 and 2, with Ophiomorpha burrows being considered, was 0.32 and 0.34, respectively. High recovery factors for both oil and gas were recorded. However, the model of the same reservoir without Ophiomorpha burrows gave reduced values of Kv/Kh of 0.12 and 0.15, respectively, with reduced recovery factors. Reservoir 3, which doesn't have burrows in the initial model, has a Kv/Kh value of 0.11 with low recovery factors in various development cases. However, when Ophiomorpha burrows were integrated into the model, Kv/Kh was 0.31, and the recovery factors increased significantly. The study has shown that geological and biostratigraphical interactions induce Kv/Kh. It has a significant optimization impact on recovery factors in concurrent development and enhances vertical sweep efficiency in EOR (Enhanced Oil Recovery). The study further shows that <em>Ophiomorpha</em> burrows improve the geologic heterogeneity quality of a reservoir (permeability anisotropy) by enhancing the injection fluid to get into micro- and macropore spaces for efficient sweeping of oil and gas into the development w","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100069"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to an increasing interest in mineral prospection, Manjo granites which are orogenic have been studied in terms of the geochemistry of whole rock and isotopes of interest found in the associated zircons. This was done to define and situate these rock unit within the context of the regional belt that is Pan African in age, establish the source of Manjo granites and their evolution during the Pan-African orogeny. More so, this study sheds more light on the controversy around the orogenic statues of granites in this section of the geological region, examines their potential for hosting molybdenum, establishes their link with other rocks within this part of the region and how they relate to the Mo-U-bearing biotite-granite in its Ekomedion neighborhood. Sixty-six zircon grains gotten from the granites and their trace elements and Lu-Hf isotopic signatures were examined. The zircon grains' ages were gotten by mass spectrometric method using the U-Pb systematics by laser ablation.The zircons ratios of U to Th varry between 0.2–2.3 relating to sources that are originally magmatic and totally different from those related to souces related to hydrothermalism and metamorphism. The granites were emplaced within the 585±17–616±12 Ma age bracket. Zircons in this study similar to the nearby Ekomedion U-Mo-bearing two mica granites and other felsic massifs found within the shear zones of central Africa (CASC)point to the fact that the Manjo granites were formed at low oxygen fugacity (log ƒO2; -15.848 to -4.515, and log ƒO2@FMQ; -17.409 to -3.677). More so, samples plot mainly outside the defined fertile fields on plots of Eu/Eu* Vs (Ce/Nd)/Y, 10000 × (Eu/Eu*)/Y Vs (Ce/Nd)/Y and Eu/Eu* Vs Dy/Yb. The above points support dominantly plagioclase fractionation in a reduced and less hydrous melt system pointing to a low Mo fertility potential of this pluton emplaced at an average Ti-in-zircon temperature of 861± 56°C. The apparent εHf(t) values for CMR-01 zircon grains range between -15.84 and -1.45 and apparent εHf(t) values for CMR-02 zircon grains vary from -25.02 to -12.39. On spidergraphs, the grainites are depleted in HREE and enriched in LREE . These plots together with εHf(t) values and other indications point to the fact that the granites were derived through partial melting of quartzo-feldspathic crustal magmatic sources. More so, the data showing a new age here show clear signs of post collisional Pan-African magmatism at ∼ 585±17 Ma in the context of a pre-drift Gondwana evolution.
由于人们对矿物勘探的兴趣与日俱增，对曼乔花岗岩（属于造山运动）进行了全岩地球化学研究，并对相关锆石中发现的相关同位素进行了研究。这样做是为了确定这些岩石单元在泛非区域带中的位置，确定曼乔花岗岩的来源及其在泛非造山运动中的演化过程。此外，这项研究还进一步揭示了围绕该地质区域这一部分花岗岩造山作用的争议，研究了这些花岗岩蕴藏钼的潜力，确定了这些花岗岩与该区域这一部分其他岩石的联系，以及这些花岗岩与 Ekomedion 附近含 Mo-U 的生物花岗岩之间的关系。从花岗岩中提取了 66 个锆石颗粒，并对其微量元素和 Lu-Hf 同位素特征进行了研究。锆石的铀-钍比值在 0.2-2.3 之间，与最初的岩浆来源有关，与热液作用和变质作用的来源完全不同。花岗岩的成因年代在 585±17-616±12 Ma 之间。本研究中的锆石与附近的 Ekomedion 含 U-Mo 的双云母花岗岩以及在非洲中部剪切带（CASC）中发现的其他长英质块状岩相似，表明曼乔花岗岩是在低富氧条件下形成的（log ƒO2; -15.848 to -4.515，log ƒO2@FMQ; -17.409 to -3.677）。此外，在 Eu/Eu* Vs (Ce/Nd)/Y、10000 × (Eu/Eu*)/Y Vs (Ce/Nd)/Y 和 Eu/Eu* Vs Dy/Yb 的曲线图上，样品主要分布在确定的肥沃区域之外。上述各点支持在一个还原的、含水量较低的熔体系统中主要是斜长石的分馏，这表明在平均Ti-in-锆石温度为861± 56°C的条件下喷发的这一深成岩具有较低的Mo孕育潜力。CMR-01锆石晶粒的表观εHf(t)值介于-15.84和-1.45之间，CMR-02锆石晶粒的表观εHf(t)值介于-25.02和-12.39之间。从蛛网图上看，晶粒中的HREE含量很低，而LREE含量很高。这些曲线图以及εHf（t）值和其他迹象表明，这些花岗岩是由部分熔融的石英长岩地壳岩浆源形成的。更重要的是，这里显示新年龄的数据清楚地表明，在冈瓦纳漂移前演化的背景下，碰撞后泛非岩浆活动的时间为 ∼ 585±17 Ma。
{"title":"Molybdenum fertility indicators, granite zircon chemistry, and U-Pb geochronology of the Manjo pluton, southwestern Cameroon","authors":"Ngambu Aloysius Afahnwie , Ralain Bryan Ngatcha , Gus Nono Kouankap Djibril , Cheo Emmanuel Suh","doi":"10.1016/j.oreoa.2024.100074","DOIUrl":"10.1016/j.oreoa.2024.100074","url":null,"abstract":"<div><div>Due to an increasing interest in mineral prospection, Manjo granites which are orogenic have been studied in terms of the geochemistry of whole rock and isotopes of interest found in the associated zircons. This was done to define and situate these rock unit within the context of the regional belt that is Pan African in age, establish the source of Manjo granites and their evolution during the Pan-African orogeny. More so, this study sheds more light on the controversy around the orogenic statues of granites in this section of the geological region, examines their potential for hosting molybdenum, establishes their link with other rocks within this part of the region and how they relate to the Mo-U-bearing biotite-granite in its Ekomedion neighborhood. Sixty-six zircon grains gotten from the granites and their trace elements and Lu-Hf isotopic signatures were examined. The zircon grains' ages were gotten by mass spectrometric method using the U-Pb systematics by laser ablation.The zircons ratios of U to Th varry between 0.2–2.3 relating to sources that are originally magmatic and totally different from those related to souces related to hydrothermalism and metamorphism. The granites were emplaced within the 585±17–616±12 Ma age bracket. Zircons in this study similar to the nearby Ekomedion U-Mo-bearing two mica granites and other felsic massifs found within the shear zones of central Africa (CASC)point to the fact that the Manjo granites were formed at low oxygen fugacity (log ƒO<sub>2</sub>; -15.848 to -4.515, and log ƒO<sub>2</sub>@FMQ; -17.409 to -3.677). More so, samples plot mainly outside the defined fertile fields on plots of Eu/Eu* Vs (Ce/Nd)/Y, 10000 × (Eu/Eu*)/Y Vs (Ce/Nd)/Y and Eu/Eu* Vs Dy/Yb. The above points support dominantly plagioclase fractionation in a reduced and less hydrous melt system pointing to a low Mo fertility potential of this pluton emplaced at an average Ti-in-zircon temperature of 861± 56°C. The apparent εHf(<em>t</em>) values for CMR-01 zircon grains range between -15.84 and -1.45 and apparent εHf<sub>(t)</sub> values for CMR-02 zircon grains vary from -25.02 to -12.39. On spidergraphs, the grainites are depleted in HREE and enriched in LREE . These plots together with εHf<sub>(t)</sub> values and other indications point to the fact that the granites were derived through partial melting of quartzo-feldspathic crustal magmatic sources. More so, the data showing a new age here show clear signs of post collisional Pan-African magmatism at ∼ 585±17 Ma in the context of a pre-drift Gondwana evolution.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100074"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-01DOI: 10.1016/j.oreoa.2024.100077
Donald A. Singer
A central part of three-part mineral assessments is estimating number of undiscovered mineral deposits. Internal consistency and well-explored deposits in grade–tonnage models reduce chances of biased estimates in three-part quantitative assessments. Estimates are of specific types of deposit permitted by geology in delineated tracts. Regardless of estimation method, each deposit type needs a grade–tonnage model constructed with well-explored deposits and estimated numbers must be consistent with this model. Local well-explored deposits are typed and statistically tested to ensure the global grade and tonnage model is representative of them.
Three-part assessments used expert judgements since 1975 that relied on analogy-based guidelines to aid in estimation of number. The advantage of expert judgements is that they can use all available information and adapt to information supplied by other experts during the assessment. A targeting method has seen limited application due to the requirement that location indicators of each possible target need to be present. Another estimation method developed around 2008 is a generalized deposit density model based on multiple deposit types which uses deposit type's median tonnage, permissive tract area, and number of known deposits in well-explored control areas. It is remarkably robust and can be applied to any deposit type in a proper permissive tract.
Advanced deposit estimations use the generalized density method to guide expert estimates. Experts can then identify possibly flawed estimates and improve estimates based on local information such as local exploration results or observations by experts thereby further reducing chances of biased estimates.
{"title":"Advances in estimations of number of undiscovered mineral deposits in three-part assessments","authors":"Donald A. Singer","doi":"10.1016/j.oreoa.2024.100077","DOIUrl":"10.1016/j.oreoa.2024.100077","url":null,"abstract":"<div><div>A central part of three-part mineral assessments is estimating number of undiscovered mineral deposits. Internal consistency and well-explored deposits in grade–tonnage models reduce chances of biased estimates in three-part quantitative assessments. Estimates are of specific types of deposit permitted by geology in delineated tracts. Regardless of estimation method, each deposit type needs a grade–tonnage model constructed with well-explored deposits and estimated numbers must be consistent with this model. Local well-explored deposits are typed and statistically tested to ensure the global grade and tonnage model is representative of them.</div><div>Three-part assessments used expert judgements since 1975 that relied on analogy-based guidelines to aid in estimation of number. The advantage of expert judgements is that they can use all available information and adapt to information supplied by other experts during the assessment. A targeting method has seen limited application due to the requirement that location indicators of each possible target need to be present. Another estimation method developed around 2008 is a generalized deposit density model based on multiple deposit types which uses deposit type's median tonnage, permissive tract area, and number of known deposits in well-explored control areas. It is remarkably robust and can be applied to any deposit type in a proper permissive tract.</div><div>Advanced deposit estimations use the generalized density method to guide expert estimates. Experts can then identify possibly flawed estimates and improve estimates based on local information such as local exploration results or observations by experts thereby further reducing chances of biased estimates.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100077"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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