Pub Date : 2026-04-01Epub Date: 2025-12-31DOI: 10.1016/j.jafrearsci.2025.105983
Ahmed Maher
The Nubia Sandstone in the Gulf of Suez, Egypt, represents unclassified, extensive Paleozoic-Mesozoic sedimentary deposits that lack discernible fossils, complicating their geological interpretation. Forty-nine subsurface well samples from the OCT-K-1 and the OCT-G.5 wells in the October Field, Gulf of Suez, were palynologically analyzed to examine Permian microflora, which hitherto has not been recorded in the region. Palynological investigation yielded 92 species of spores with affinities to lycopsids, ferns, and Equisetidae representing 50 genera, 75 species of gymnosperm pollen with affinities to conifers and cycads of 49 genera, and 53 species of microphytoplankton and fungi. Petrographic and palynofacies analyses suggest that the sediments were deposited in a mixed terrestrial and marine environment. These depositional environments preserved charcoal, coal macerals, a fossil resin, abundant mineralized large-sized plant remains, and pyrite framboids. This study successfully differentiates the Nubia Sandstone in the October Field, which is crucial for hydrocarbon exploration in the Gulf of Suez.
{"title":"Integrative palynological and petrographic analysis of the Permo-Carboniferous deposits in the October Field, Gulf of Suez, Egypt","authors":"Ahmed Maher","doi":"10.1016/j.jafrearsci.2025.105983","DOIUrl":"10.1016/j.jafrearsci.2025.105983","url":null,"abstract":"<div><div>The Nubia Sandstone in the Gulf of Suez, Egypt, represents unclassified, extensive Paleozoic-Mesozoic sedimentary deposits that lack discernible fossils, complicating their geological interpretation. Forty-nine subsurface well samples from the OCT-K-1 and the OCT-G.5 wells in the October Field, Gulf of Suez, were palynologically analyzed to examine Permian microflora, which hitherto has not been recorded in the region. Palynological investigation yielded 92 species of spores with affinities to lycopsids, ferns, and Equisetidae representing 50 genera, 75 species of gymnosperm pollen with affinities to conifers and cycads of 49 genera, and 53 species of microphytoplankton and fungi. Petrographic and palynofacies analyses suggest that the sediments were deposited in a mixed terrestrial and marine environment. These depositional environments preserved charcoal, coal macerals, a fossil resin, abundant mineralized large-sized plant remains, and pyrite framboids. This study successfully differentiates the Nubia Sandstone in the October Field, which is crucial for hydrocarbon exploration in the Gulf of Suez.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 105983"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-07DOI: 10.1016/j.jafrearsci.2026.106014
Andreas Scharf , Frank Mattern , Abdul Razak Al-Sayigh , Laura Galluccio , Gianluca Frijia
We studied the rarely exposed Oligocene Ma'ahm Beds at Quriyat for their lithostratigraphy, microfacies and depositional environment. In addition, we intend to contribute to the general understanding of coral patch reefs. Our bed-scale logs include thin-section analyses of standard microfacies (SMF) types allowing direct comparisons with those of the Ma'ahm Beds 80 km to the NW in the Al-Khod area, the so far best-described outcrop area of Oligocene age in Oman. The Ma'ahm Beds at Quriyat are ∼50 m thick, which lies within the thickness range of the Ma'ahm Beds at Al-Khod. Coral patch reef complexes occur in both places. The one at Quriyat contains reefs of different symmetries. The SMF types of the massively bedded reefs and the associated bioclastic limestone beds represent facies zone 7 as at Al-Khod, indicating a depositional environment within the photic zone, above fair-weather wave base, in an open lagoon. In both regions, the lagoons were most likely protected by coral barrier reefs with intervening gaps. The patch reefs at Quriyat were abandoned, and new ones formed in oceanward direction to keep up with a dropping eustatic sea-level. At the flanks of the largest patch reef at Quriyat, bioclastic limestones with reef debris display onlap geometries. Only the limestones at Quriyat are associated with silty marl and calcareous, marly sandstone, which accumulated in a foreshore environment, either as longshore drift, or cays or combination/alternation thereof. These siliciclastic deposits are likely more voluminous than the limestones of the Ma'ahm Beds in the eastern part of the Arabian Plate, which should be considered when constructing paleo-facies maps. This abundant fine-grained marly material implies that Oligocene aquiclude horizons exist. We suggest that coral patch reefs should measure at least 5 m in diameter to fulfill typical ecological reef functions.
{"title":"The Oligocene “Ma'ahm Beds” of NE Oman (eastern Arabia): Microfacies and lithostratigraphy of a mixed carbonate system with coral patch reefs","authors":"Andreas Scharf , Frank Mattern , Abdul Razak Al-Sayigh , Laura Galluccio , Gianluca Frijia","doi":"10.1016/j.jafrearsci.2026.106014","DOIUrl":"10.1016/j.jafrearsci.2026.106014","url":null,"abstract":"<div><div>We studied the rarely exposed Oligocene Ma'ahm Beds at Quriyat for their lithostratigraphy, microfacies and depositional environment. In addition, we intend to contribute to the general understanding of coral patch reefs. Our bed-scale logs include thin-section analyses of standard microfacies (SMF) types allowing direct comparisons with those of the Ma'ahm Beds 80 km to the NW in the Al-Khod area, the so far best-described outcrop area of Oligocene age in Oman. The Ma'ahm Beds at Quriyat are ∼50 m thick, which lies within the thickness range of the Ma'ahm Beds at Al-Khod. Coral patch reef complexes occur in both places. The one at Quriyat contains reefs of different symmetries. The SMF types of the massively bedded reefs and the associated bioclastic limestone beds represent facies zone 7 as at Al-Khod, indicating a depositional environment within the photic zone, above fair-weather wave base, in an open lagoon. In both regions, the lagoons were most likely protected by coral barrier reefs with intervening gaps. The patch reefs at Quriyat were abandoned, and new ones formed in oceanward direction to keep up with a dropping eustatic sea-level. At the flanks of the largest patch reef at Quriyat, bioclastic limestones with reef debris display onlap geometries. Only the limestones at Quriyat are associated with silty marl and calcareous, marly sandstone, which accumulated in a foreshore environment, either as longshore drift, or cays or combination/alternation thereof. These siliciclastic deposits are likely more voluminous than the limestones of the Ma'ahm Beds in the eastern part of the Arabian Plate, which should be considered when constructing paleo-facies maps. This abundant fine-grained marly material implies that Oligocene aquiclude horizons exist. We suggest that coral patch reefs should measure at least 5 m in diameter to fulfill typical ecological reef functions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106014"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-05DOI: 10.1016/j.jafrearsci.2026.106005
Bosy A. El-Haddad , Ahmed M. Youssef , Tawfiq M. Mahran , AbdelHammed A. El-Shater , Hamid Reza Pourghasemi
This study employed a sedimentological investigation and remote sensing techniques to reconstruct the geological progression of the Egyptian Nile in the west and southwest of Sohag City. A viable methodology for mapping the area was developed using “Landsat-Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) images. Three processing techniques were applied, including principal component analysis (PCA), minimal noise fraction (MNF), and decoration stretch (DS) followed by a supervised classification, to map the area. The Katkut and Abu Retag formations were delineated and extracted from the adjacent units. A comprehensive field investigation was conducted to understand the lithological facies of these deposits, verify the remote sensing results, and construct a depositional model. The results revealed a diverse range of continental sediments and variations in depositional environments. These sediments represent two phases of Nile development, from the late Oligocene to the middle to late Miocene era. Our findings emphasized the significant role of paleoclimate, local and regional tectonics, and paleogeomorphology on the geological history of the study area. Climate indicators demonstrated a recurring pattern of climatic transformation, transitioning from humid and semiarid regions to dry conditions. The evolution of the region was significantly shaped by the Nubian Swell, the development of NW-trending grabens, and the hanging walls that linked fault segments, governing the Pre-Eonile and Eonile systems. Three distinct phases were identified in the history of provenance: sediment rich chert carbonates, quartz-rich deposits, and mixtures of detritus containing carbonates, quartz, and pieces of basement rock. These stages indicate shifts in the source location owing to the shifting tectonic activity. This research provides valuable insights and contributions into the Nile's evolution, the Nile's geological history, potential resource exploration, and offers a foundation for future research in the area.
{"title":"Mapping of the pre-Eonile - Eonile sediments using remote sensing technique and sedimentological investigation in the western desert of Egypt","authors":"Bosy A. El-Haddad , Ahmed M. Youssef , Tawfiq M. Mahran , AbdelHammed A. El-Shater , Hamid Reza Pourghasemi","doi":"10.1016/j.jafrearsci.2026.106005","DOIUrl":"10.1016/j.jafrearsci.2026.106005","url":null,"abstract":"<div><div>This study employed a sedimentological investigation and remote sensing techniques to reconstruct the geological progression of the Egyptian Nile in the west and southwest of Sohag City. A viable methodology for mapping the area was developed using “Landsat-Enhanced Thematic Mapper Plus (ETM<sup>+</sup>) and Operational Land Imager (OLI) images. Three processing techniques were applied, including principal component analysis (PCA), minimal noise fraction (MNF), and decoration stretch (DS) followed by a supervised classification, to map the area. The Katkut and Abu Retag formations were delineated and extracted from the adjacent units. A comprehensive field investigation was conducted to understand the lithological facies of these deposits, verify the remote sensing results, and construct a depositional model. The results revealed a diverse range of continental sediments and variations in depositional environments. These sediments represent two phases of Nile development, from the late Oligocene to the middle to late Miocene era. Our findings emphasized the significant role of paleoclimate, local and regional tectonics, and paleogeomorphology on the geological history of the study area. Climate indicators demonstrated a recurring pattern of climatic transformation, transitioning from humid and semiarid regions to dry conditions. The evolution of the region was significantly shaped by the Nubian Swell, the development of NW-trending grabens, and the hanging walls that linked fault segments, governing the Pre-Eonile and Eonile systems. Three distinct phases were identified in the history of provenance: sediment rich chert carbonates, quartz-rich deposits, and mixtures of detritus containing carbonates, quartz, and pieces of basement rock. These stages indicate shifts in the source location owing to the shifting tectonic activity. This research provides valuable insights and contributions into the Nile's evolution, the Nile's geological history, potential resource exploration, and offers a foundation for future research in the area.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106005"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-05DOI: 10.1016/j.jafrearsci.2026.106001
Alaaeddine Ait Ayad, Soufiane Maimouni, Yousra Morsli, Ahmed Fekri
Conventional lithological mapping techniques are often challenging and intricate, particularly in inaccessible areas. Integrating remote sensing and Machine Learning Algorithms (MLA) provides a robust and precise tool for interpreting geological structures. Exploiting remote sensing data using advanced MLA enhances lithological mapping through spectral classification. The objective of this research is to analyze and assess the effectiveness of ML methods: Support Vector Machine (SVM), Random Forest (RF), K-Nearest Neighbors (k-NN), Artificial Neural Network (ANN) and Maximum Likelihood Classifier (MLC) for lithological mapping by using ASTER data. Remote sensing data combined with machine learning (particularly SVM) can be an effective solution for detailed mapping of rocks with the same mineralogy but different grain sizes. Applying these techniques to the Sebt Brikiine pluton allowed for distinguishing three granitic facies and two units. The evaluation of these different methods and the comparison of their results have shown that the methods showed that the best overall accuracy of 97 % and a Kappa coefficient of 0.95 were achieved with the SVM approach. whereas the RF approach showed an overall accuracy of approximately 96 % with a Kappa coefficient of 0.93. Although the k-NN approach yielded an OA of around 92 % and a Kappa coefficient of 0.87, the ANN approach provided a lower overall accuracy of 83 % with a Kappa coefficient of 0.74 in comparison with other classification approaches. MLC provides the lowest overall accuracy value of 68 % and Kappa coefficient of 0.51. The results of this comparison study lead to the conclusion that SVM, as a supervised learning algorithm, is the most suitable and accurate technique for mapping granitic facies. It delimits a circumscribed SW granitic unit, composed of medium-grained granite surrounded by coarse-grained facies and overlain by frozen edges of fine-grained granite. This circumscribed structure cuts across an earlier NE unit composed of medium granite with vacuoles. These units are located in extensions along the lithospheric fault of the Western Meseta in late Variscan period of Morocco. This technique can be extended to the granitic bodies of the Variscan belt in Morocco, which are intrinsic to the main NE- and ENE-trending lithospheric faults.
{"title":"Advanced lithological mapping using ASTER data and machine learning: Sebt Brikiine pluton, Rehamna massif, Morocco","authors":"Alaaeddine Ait Ayad, Soufiane Maimouni, Yousra Morsli, Ahmed Fekri","doi":"10.1016/j.jafrearsci.2026.106001","DOIUrl":"10.1016/j.jafrearsci.2026.106001","url":null,"abstract":"<div><div>Conventional lithological mapping techniques are often challenging and intricate, particularly in inaccessible areas. Integrating remote sensing and Machine Learning Algorithms (MLA) provides a robust and precise tool for interpreting geological structures. Exploiting remote sensing data using advanced MLA enhances lithological mapping through spectral classification. The objective of this research is to analyze and assess the effectiveness of ML methods: Support Vector Machine (SVM), Random Forest (RF), K-Nearest Neighbors (k-NN), Artificial Neural Network (ANN) and Maximum Likelihood Classifier (MLC) for lithological mapping by using ASTER data. Remote sensing data combined with machine learning (particularly SVM) can be an effective solution for detailed mapping of rocks with the same mineralogy but different grain sizes. Applying these techniques to the Sebt Brikiine pluton allowed for distinguishing three granitic facies and two units. The evaluation of these different methods and the comparison of their results have shown that the methods showed that the best overall accuracy of 97 % and a Kappa coefficient of 0.95 were achieved with the SVM approach. whereas the RF approach showed an overall accuracy of approximately 96 % with a Kappa coefficient of 0.93. Although the k-NN approach yielded an OA of around 92 % and a Kappa coefficient of 0.87, the ANN approach provided a lower overall accuracy of 83 % with a Kappa coefficient of 0.74 in comparison with other classification approaches. MLC provides the lowest overall accuracy value of 68 % and Kappa coefficient of 0.51. The results of this comparison study lead to the conclusion that SVM, as a supervised learning algorithm, is the most suitable and accurate technique for mapping granitic facies. It delimits a circumscribed SW granitic unit, composed of medium-grained granite surrounded by coarse-grained facies and overlain by frozen edges of fine-grained granite. This circumscribed structure cuts across an earlier NE unit composed of medium granite with vacuoles. These units are located in extensions along the lithospheric fault of the Western Meseta in late Variscan period of Morocco. This technique can be extended to the granitic bodies of the Variscan belt in Morocco, which are intrinsic to the main NE- and ENE-trending lithospheric faults.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106001"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-18DOI: 10.1016/j.jafrearsci.2026.106035
Mohamed Ait Addi , Mohamed Aissa , Ilyasse Loudaoued , Abdel-Ali Kharis , Mohammed El Azmi , Fouad Lotfi , Mohmed Aissa , Abderrahim Ardouz , Antonio Delgado Huertas , Daoud El Azmi
The Bou Skour copper deposit is located in the eastern part of the Moroccan Anti-Atlas, approximately 56km east of Ouarzazate city, exhibits geological, textural and mineralogical characteristics that attest to a complex development history. Copper mineralization is hosted mainly in Lower Ediacaran andesite and granodiorite. The deposit resulted from at least two superimposed mineralizing events: i) a first, early event produced porphyry-type mineralization with chalcopyrite, bornite, pyrite and sphalerite. ii) A second, later event was responsible for the development of vein-type mineralization, mainly materialized by three veins: Filon Principal, Filon 1 and Filon 2. The mineralization is predominantly composed of pyrite, chalcopyrite, bornite, arsenopyrite, sphalerite, galena, tennantite, aikinite and wittichenite. Hydrothermal fluids have altered the granodiorite and andesite in several phases, forming potassic (K-feldspar + biotite), phyllic (chlorite), argillic (kaolinite), and propylitic (epidote) mineral zones. A portion of the silver in the Bou Skour deposit occurs in native form, while another fraction is present as trace elements within copper sulfides, primarily bornite and chalcocite. The ore-associated calcite has δ13C values range of - 9 to +2.9 ‰ and δ18O values of +19.5 to +22 ‰. These isotopic signatures are consistent with interaction of a crust sourced fluid and surrounding rocks, or with meteoric waters enriched in organic matter. In addition, sulfur isotopic signatures (δ34S) measured in bornite and chalcopyrite are relatively homogeneous, with values of between −7.86 andto −4.14 ‰, indicating a purely magmatic origin for sulfur.
Fluid inclusion study of porphyry-type mineralization reveals formation by paleo magmatic-hydrothermal circulation involving two distinct fluid types: (1) a hot magmatic fluid that underwent phase separation through boiling, generating both a hypersaline liquid (44.78–61.64 wt% NaCl equiv.) and a vapor phase (5.86–7.86 wt% NaCl equiv.), exhibiting comparable homogenization temperatures (450–500 °C); and (2) a second aqueous fluid characterized by moderate temperatures (237.9–452 °C) and low to intermediate salinity (19.4–38.78 wt% NaCl equiv.), indicating mixing with external fluids. The vein-type mineralization which represents hydrothermal conduits exhibiting moderately low temperatures (180–310 °C) and moderate salinities (14.25–28.66 wt% NaCl equiv.) records the late-stage evolution of the hydrothermal system associated with Hercynian tectonic activity.
{"title":"The Bou Skour Cu–Ag deposit (Anti-Atlas. Morocco): Evidence of a porphyry copper system from mineralogy, alteration, geochemistry, isotopes, and fluid inclusions","authors":"Mohamed Ait Addi , Mohamed Aissa , Ilyasse Loudaoued , Abdel-Ali Kharis , Mohammed El Azmi , Fouad Lotfi , Mohmed Aissa , Abderrahim Ardouz , Antonio Delgado Huertas , Daoud El Azmi","doi":"10.1016/j.jafrearsci.2026.106035","DOIUrl":"10.1016/j.jafrearsci.2026.106035","url":null,"abstract":"<div><div>The Bou Skour copper deposit is located in the eastern part of the Moroccan Anti-Atlas, approximately 56km east of Ouarzazate city, exhibits geological, textural and mineralogical characteristics that attest to a complex development history. Copper mineralization is hosted mainly in Lower Ediacaran andesite and granodiorite. The deposit resulted from at least two superimposed mineralizing events: i) a first, early event produced porphyry-type mineralization with chalcopyrite, bornite, pyrite and sphalerite. ii) A second, later event was responsible for the development of vein-type mineralization, mainly materialized by three veins: Filon Principal, Filon 1 and Filon 2. The mineralization is predominantly composed of pyrite, chalcopyrite, bornite, arsenopyrite, sphalerite, galena, tennantite, aikinite and wittichenite. Hydrothermal fluids have altered the granodiorite and andesite in several phases, forming potassic (K-feldspar + biotite), phyllic (chlorite), argillic (kaolinite), and propylitic (epidote) mineral zones. A portion of the silver in the Bou Skour deposit occurs in native form, while another fraction is present as trace elements within copper sulfides, primarily bornite and chalcocite. The ore-associated calcite has δ<sup>13</sup>C values range of - 9 to +2.9 ‰ and δ<sup>18</sup>O values of +19.5 to +22 ‰. These isotopic signatures are consistent with interaction of a crust sourced fluid and surrounding rocks, or with meteoric waters enriched in organic matter. In addition, sulfur isotopic signatures (δ<sup>34</sup>S) measured in bornite and chalcopyrite are relatively homogeneous, with values of between −7.86 andto −4.14 ‰, indicating a purely magmatic origin for sulfur.</div><div>Fluid inclusion study of porphyry-type mineralization reveals formation by paleo magmatic-hydrothermal circulation involving two distinct fluid types: (1) a hot magmatic fluid that underwent phase separation through boiling, generating both a hypersaline liquid (44.78–61.64 wt% NaCl equiv.) and a vapor phase (5.86–7.86 wt% NaCl equiv.), exhibiting comparable homogenization temperatures (450–500 °C); and (2) a second aqueous fluid characterized by moderate temperatures (237.9–452 °C) and low to intermediate salinity (19.4–38.78 wt% NaCl equiv.), indicating mixing with external fluids. The vein-type mineralization which represents hydrothermal conduits exhibiting moderately low temperatures (180–310 °C) and moderate salinities (14.25–28.66 wt% NaCl equiv.) records the late-stage evolution of the hydrothermal system associated with Hercynian tectonic activity.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106035"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-21DOI: 10.1016/j.jafrearsci.2026.106029
Roland Asare , Raymond Webrah Kazapoe , Obed Fiifi Fynn , Samuel Dzidefo Sagoe , Joseph Turkson , Kwabina Ibrahim , Patrick Asamoah Sakyi , Frank Kwakye Nyame
This study examined groundwater hydrogeochemistry, pollution sources, and health risks in the mining-dominated Atiwa West District of Ghana using 56 borehole and well samples collected in dry and wet seasons. Electrical conductivity and total dissolved solids ranged from 67.2 to 692 μS/cm and 33.6–389 mg/L, respectively, classifying the water as fresh. Iron (mean 2.05 mg/L, wet) and manganese (mean 0.33 mg/L, wet) exceeded WHO aesthetic limits, while arsenic (max 0.006 mg/L) and mercury (max 0.002 mg/L) approached guideline values. Principal Component Analysis explained over 80 % of variance, linking carbonate weathering, redox mobilization of Fe–Mn, and sulphide oxidation as key geochemical controls, with anthropogenic contributions evident in wet-season recharge. Saturation index modeling showed persistent undersaturation of evaporite minerals (gypsum, halite, sylvite), indicating active dissolution, while carbonate minerals (calcite, aragonite, dolomite) were near equilibrium to supersaturated, reflecting their buffering role in aquifers. Water Quality Index (WQI) ranged from excellent (<25) to very poor (>200), with deteriorated quality more common near mining and agricultural zones in the wet season. HHRA results indicate that most risks remain within acceptable limits, though non-carcinogenic HI exceedances reached 3.97 percent in adults and 7.66 percent in children during the dry season, declining to 2.43 percent and 4.83 percent in the wet season. Cancer risk exceedances affected 8.02 percent of adults and 12.69 percent of children in the dry season, reducing to 5.60 percent and 9.26 percent in the wet season, with Mn and Cu as the dominant contributors to non-carcinogenic risk.
{"title":"Groundwater quality, pollution sources, and health risk assessment in a mining-dominated district: A case study from Atiwa West, Ghana","authors":"Roland Asare , Raymond Webrah Kazapoe , Obed Fiifi Fynn , Samuel Dzidefo Sagoe , Joseph Turkson , Kwabina Ibrahim , Patrick Asamoah Sakyi , Frank Kwakye Nyame","doi":"10.1016/j.jafrearsci.2026.106029","DOIUrl":"10.1016/j.jafrearsci.2026.106029","url":null,"abstract":"<div><div>This study examined groundwater hydrogeochemistry, pollution sources, and health risks in the mining-dominated Atiwa West District of Ghana using 56 borehole and well samples collected in dry and wet seasons. Electrical conductivity and total dissolved solids ranged from 67.2 to 692 μS/cm and 33.6–389 mg/L, respectively, classifying the water as fresh. Iron (mean 2.05 mg/L, wet) and manganese (mean 0.33 mg/L, wet) exceeded WHO aesthetic limits, while arsenic (max 0.006 mg/L) and mercury (max 0.002 mg/L) approached guideline values. Principal Component Analysis explained over 80 % of variance, linking carbonate weathering, redox mobilization of Fe–Mn, and sulphide oxidation as key geochemical controls, with anthropogenic contributions evident in wet-season recharge. Saturation index modeling showed persistent undersaturation of evaporite minerals (gypsum, halite, sylvite), indicating active dissolution, while carbonate minerals (calcite, aragonite, dolomite) were near equilibrium to supersaturated, reflecting their buffering role in aquifers. Water Quality Index (WQI) ranged from excellent (<25) to very poor (>200), with deteriorated quality more common near mining and agricultural zones in the wet season. HHRA results indicate that most risks remain within acceptable limits, though non-carcinogenic HI exceedances reached 3.97 percent in adults and 7.66 percent in children during the dry season, declining to 2.43 percent and 4.83 percent in the wet season. Cancer risk exceedances affected 8.02 percent of adults and 12.69 percent of children in the dry season, reducing to 5.60 percent and 9.26 percent in the wet season, with Mn and Cu as the dominant contributors to non-carcinogenic risk.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106029"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-16DOI: 10.1016/j.jafrearsci.2026.106034
Houssem Tabbabi , Rim Temani , Gabriele Niccolini , Nadia Ben Moktar , Barbara Balestra , Hayet Khayati Ammar , Salah Mahmoudi , Adele Bertini
The CNH (Coupe Nabeul Houwaria) sedimentary succession (Cap Bon, NE Tunisia) was previously attributed to the Piacenzian-Gelasian transition based on preliminary micropaleontological data. This study re-evaluates that hypothesis through an integrated stratigraphic approach that combines calcareous nannofossils, planktonic foraminifera, and palynological data. Calcareous nannofossil assemblages are dominated by Reticulofenestra and Sphenolithus, with the consistent presence of Reticulofenestra pseudoumbilicus >7 μm and the absence of Quaternary marker taxa, constraining the succession to no younger than 3.82 Ma (top of Zone CNPL3). Palynological evidence, including subtropical to warm-temperate vegetation and dinoflagellate cyst assemblages lacking cold indicators, supports a warm climate incompatible with glacial conditions. This interpretation is further reinforced by the absence of Bythocythere turgida, an ostracod known as a significant “Northern guest”. The presence of Globorotalia puncticulata restricts the maximum age of the succession to no older than its first occurrence at ca. 4.52 Ma, while the absence of Globorotalia margaritae suggests even an age younger than 3.98 Ma (its last common occurrence). Taken together, these data frame the CNH succession within a time interval between ca. 4.52 (or 3.98 Ma) and 3.82 Ma, indicating a late Zanclean age and calling for a substantial revision of its lithostratigraphic assignment. The study highlights the need for high-resolution, multi-proxy analyses and, in particular, future magnetostratigraphic investigations, to improve regional chronostratigraphic models in NE Tunisia and strengthen correlations with the global stratigraphic framework.
{"title":"Palynological and biostratigraphical contributions to the stratigraphic understanding of Pliocene-Pleistocene deposits in the Cap Bon area (northeast Tunisia)","authors":"Houssem Tabbabi , Rim Temani , Gabriele Niccolini , Nadia Ben Moktar , Barbara Balestra , Hayet Khayati Ammar , Salah Mahmoudi , Adele Bertini","doi":"10.1016/j.jafrearsci.2026.106034","DOIUrl":"10.1016/j.jafrearsci.2026.106034","url":null,"abstract":"<div><div>The CNH (Coupe Nabeul Houwaria) sedimentary succession (Cap Bon, NE Tunisia) was previously attributed to the Piacenzian-Gelasian transition based on preliminary micropaleontological data. This study re-evaluates that hypothesis through an integrated stratigraphic approach that combines calcareous nannofossils, planktonic foraminifera, and palynological data. Calcareous nannofossil assemblages are dominated by <em>Reticulofenestra</em> and <em>Sphenolithus</em>, with the consistent presence of <em>Reticulofenestra pseudoumbilicus</em> >7 μm and the absence of Quaternary marker taxa, constraining the succession to no younger than 3.82 Ma (top of Zone CNPL3). Palynological evidence, including subtropical to warm-temperate vegetation and dinoflagellate cyst assemblages lacking cold indicators, supports a warm climate incompatible with glacial conditions. This interpretation is further reinforced by the absence of <em>Bythocythere turgida</em>, an ostracod known as a significant “Northern guest”. The presence of <em>Globorotalia puncticulata</em> restricts the maximum age of the succession to no older than its first occurrence at ca. 4.52 Ma, while the absence of <em>Globorotalia margaritae</em> suggests even an age younger than 3.98 Ma (its last common occurrence). Taken together, these data frame the CNH succession within a time interval between ca. 4.52 (or 3.98 Ma) and 3.82 Ma, indicating a late Zanclean age and calling for a substantial revision of its lithostratigraphic assignment. The study highlights the need for high-resolution, multi-proxy analyses and, in particular, future magnetostratigraphic investigations, to improve regional chronostratigraphic models in NE Tunisia and strengthen correlations with the global stratigraphic framework.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106034"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-22DOI: 10.1016/j.jafrearsci.2026.106031
Heba S. Mubarak , Mokhles K. Azer , Adel A. Surour , Hilmy E. Moussa , Paul D. Asimow , Mona Kabesh , Faris A. Abanumay
The granitic rocks in Wadi Hangaliya, in the south Eastern Desert of Egypt, represent an offshoot of the Gebel Nugrus intrusion. They include alkali feldspar granite, syenogranite, sheared granite, and highly mineralized granite in the vicinity of the well-known Hangaliya gold mine. Geochemically, the suite has peraluminous, calc-alkaline, and highly fractionated characteristics. Whole-rock geochemical data indicate overall enrichment in rare-earth elements; light rare earth elements are enriched compared to heavy rare earth elements and there are prominent negative Eu anomalies. Heterogeneity is noted in ratios of elements that are similarly incompatible during fractionation (K/Rb, Zr/Rb and Ba/Nb). Field relations and geochemical characteristics of the granite suite are consistent with generation of parental magma in a post-collisional tectonic setting through partial melting of a juvenile igneous crustal source, followed by extensive fractional crystallization with some upper crustal contamination. Some samples are garnet-bearing, with an almandine-dominated composition often associated with magmatic garnets crystallized from I-type magma at low pressure. Two arsenic-bearing phases were found and studied in the Hangaliya gold mine samples: scorodite [FeAsO4 2H2O] and arsenosiderite [Ca2Fe3(AsO4)3O2 3H2O], which is considered to have formed by alteration of arsenopyrite and scorodite. Gold alloys were readily detected in Hangaliya gold mine samples and are characterized by variable Au contents (31–83 wt%).
{"title":"Mineral chemistry and whole-rock geochemistry of highly fractionated post-collisional granites in the Hangaliya gold mine area, Arabian-Nubian Shield, Egypt","authors":"Heba S. Mubarak , Mokhles K. Azer , Adel A. Surour , Hilmy E. Moussa , Paul D. Asimow , Mona Kabesh , Faris A. Abanumay","doi":"10.1016/j.jafrearsci.2026.106031","DOIUrl":"10.1016/j.jafrearsci.2026.106031","url":null,"abstract":"<div><div>The granitic rocks in Wadi Hangaliya, in the south Eastern Desert of Egypt, represent an offshoot of the Gebel Nugrus intrusion. They include alkali feldspar granite, syenogranite, sheared granite, and highly mineralized granite in the vicinity of the well-known Hangaliya gold mine. Geochemically, the suite has peraluminous, calc-alkaline, and highly fractionated characteristics. Whole-rock geochemical data indicate overall enrichment in rare-earth elements; light rare earth elements are enriched compared to heavy rare earth elements and there are prominent negative Eu anomalies. Heterogeneity is noted in ratios of elements that are similarly incompatible during fractionation (K/Rb, Zr/Rb and Ba/Nb). Field relations and geochemical characteristics of the granite suite are consistent with generation of parental magma in a post-collisional tectonic setting through partial melting of a juvenile igneous crustal source, followed by extensive fractional crystallization with some upper crustal contamination. Some samples are garnet-bearing, with an almandine-dominated composition often associated with magmatic garnets crystallized from I-type magma at low pressure. Two arsenic-bearing phases were found and studied in the Hangaliya gold mine samples: scorodite [FeAsO<sub>4</sub> <span><math><mrow><mo>·</mo></mrow></math></span> 2H<sub>2</sub>O] and arsenosiderite [Ca<sub>2</sub>Fe<sub>3</sub>(AsO<sub>4</sub>)<sub>3</sub>O<sub>2</sub> <span><math><mrow><mo>·</mo></mrow></math></span> 3H<sub>2</sub>O], which is considered to have formed by alteration of arsenopyrite and scorodite. Gold alloys were readily detected in Hangaliya gold mine samples and are characterized by variable Au contents (31–83 wt%).</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106031"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146090712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-02DOI: 10.1016/j.jafrearsci.2026.105993
S. Raja Ranganathan , Nada Alzaben , Abdulaziz G. Alghamdi , Hatim Dafaalla
Soil salinity is a prevalent environmental issue, especially in coastal environments, which exacerbate the conditions favouring salt accumulation in the root zone (saline intrusion, poor drainage, and evapotranspiration). The study focused to create a robust, cloud-based method for mapping soil salinity using remote sensing data and more sophisticated machine learning approaches. Remote imagery from Sentinel-2 was used to generate spectral indices, while topographic variables were derived from DEM products within Google Earth Engine. Two ensemble learning models were created: Random Forest (RF) and Light Gradient Boosting Machine (LightGBM), to determine soil electrical conductivity (EC) based on the environmental variables above. The two models were evaluated with calibration, validation and cross-validation tests. The RF produced the best results with R2 values of 0.81, 0.68, 0.59 and RMSE of 14.8, 18.45 and 20.15 dS m−1 for the data splits. The LightGBM produced R2 values of 0.73, 0.65, 0.56 and RMSE values of 18.9, 18.75 and 20.25 dS m−1, reflecting lower predictive accuracy compared to other models, yet still within an acceptable range. The relative performance index of quantification (RPIQ) confirmed the improved predictability of RF. The results confirm the feasibility of cloud-computing capabilities and satellite-based environmental characteristics with machine learning to assess and monitor soil salinity in dynamic coastal environments. The method also provides land managers and policy makers with a scalable option to assess salinity risk to assist with sustainable agricultural practices in regions affected by salt.
{"title":"Cloud-based soil salinity mapping using remote sensing and machine learning approaches","authors":"S. Raja Ranganathan , Nada Alzaben , Abdulaziz G. Alghamdi , Hatim Dafaalla","doi":"10.1016/j.jafrearsci.2026.105993","DOIUrl":"10.1016/j.jafrearsci.2026.105993","url":null,"abstract":"<div><div>Soil salinity is a prevalent environmental issue, especially in coastal environments, which exacerbate the conditions favouring salt accumulation in the root zone (saline intrusion, poor drainage, and evapotranspiration). The study focused to create a robust, cloud-based method for mapping soil salinity using remote sensing data and more sophisticated machine learning approaches. Remote imagery from Sentinel-2 was used to generate spectral indices, while topographic variables were derived from DEM products within Google Earth Engine. Two ensemble learning models were created: Random Forest (RF) and Light Gradient Boosting Machine (LightGBM), to determine soil electrical conductivity (EC) based on the environmental variables above. The two models were evaluated with calibration, validation and cross-validation tests. The RF produced the best results with R<sup>2</sup> values of 0.81, 0.68, 0.59 and RMSE of 14.8, 18.45 and 20.15 dS m<sup>−1</sup> for the data splits. The LightGBM produced R<sup>2</sup> values of 0.73, 0.65, 0.56 and RMSE values of 18.9, 18.75 and 20.25 dS m<sup>−1</sup>, reflecting lower predictive accuracy compared to other models, yet still within an acceptable range. The relative performance index of quantification (RPIQ) confirmed the improved predictability of RF. The results confirm the feasibility of cloud-computing capabilities and satellite-based environmental characteristics with machine learning to assess and monitor soil salinity in dynamic coastal environments. The method also provides land managers and policy makers with a scalable option to assess salinity risk to assist with sustainable agricultural practices in regions affected by salt.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 105993"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-04-01Epub Date: 2026-01-05DOI: 10.1016/j.jafrearsci.2026.106000
D.R. Ferreira , M.B. Klausen , B.P. Von der Heyden , P. Le Roux
Renewed interest in the Tantalite Valley Complex has uncovered PGE-enriched magmatic sulphides. Despite this, little is known about the internal stratigraphy of the complex. This study aims to rectify this paucity of research by investigating the internal stratigraphy and architecture of the TVC. These aims have been achieved through field mapping, petrographic, geochemical, and isotopic studies from an extensive and representative sample set. These techniques have shed light on the magmatic evolution of the study site, and the complex is interpreted to be a composite of three to four nested intrusions. The nested intrusions are overwhelmingly mafic and are layered in nature, in contrast to earlier interpretations in the literature. Additionally, these intrusions have undergone limited differentiation, where geochemical evidence reveals cryptic layering reversals interpreted to reflect open system magmatic recharge. Isotopic evidence supports these interpretations and underpins an interplay involving time, magma replenishments, tectonism, and the establishment of new magma chambers that ultimately formed the complicated stratigraphy of the Tantalite Valley Complex. This study highlights the convoluted evolution of this intrusion during the Namaqua orogeny, having regional implications for the evolution of several similar intrusions in the surrounding area and indeed across global orogenies where mafic-ultramafic bodies exist.
{"title":"Magmatic architecture and evolution of the Mesoproterozoic nested layered mafic intrusions of the Tantalite Valley Complex, southern Namibia","authors":"D.R. Ferreira , M.B. Klausen , B.P. Von der Heyden , P. Le Roux","doi":"10.1016/j.jafrearsci.2026.106000","DOIUrl":"10.1016/j.jafrearsci.2026.106000","url":null,"abstract":"<div><div>Renewed interest in the Tantalite Valley Complex has uncovered PGE-enriched magmatic sulphides. Despite this, little is known about the internal stratigraphy of the complex. This study aims to rectify this paucity of research by investigating the internal stratigraphy and architecture of the TVC. These aims have been achieved through field mapping, petrographic, geochemical, and isotopic studies from an extensive and representative sample set. These techniques have shed light on the magmatic evolution of the study site, and the complex is interpreted to be a composite of three to four nested intrusions. The nested intrusions are overwhelmingly mafic and are layered in nature, in contrast to earlier interpretations in the literature. Additionally, these intrusions have undergone limited differentiation, where geochemical evidence reveals cryptic layering reversals interpreted to reflect open system magmatic recharge. Isotopic evidence supports these interpretations and underpins an interplay involving time, magma replenishments, tectonism, and the establishment of new magma chambers that ultimately formed the complicated stratigraphy of the Tantalite Valley Complex. This study highlights the convoluted evolution of this intrusion during the Namaqua orogeny, having regional implications for the evolution of several similar intrusions in the surrounding area and indeed across global orogenies where mafic-ultramafic bodies exist.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106000"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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