Pub Date : 2025-12-05DOI: 10.1016/j.jafrearsci.2025.105964
Benjamin F. Walter , Ndukauba Egesi , Mohsin Raza , Micheal Agbebia , Fadila Adamu , R. Johannes Giebel , Michael A.W. Marks , Emmanuel Chidi Ugbaja , Gregor Markl
Unconformity-related hydrothermal vein-type deposits are key sources of high-purity fluorite, baryte, and base metals, with occurrences in Nigeria, particularly along the Benue Trough. However, the genesis of the Nigerian deposits is not well understood. This study examines fluid inclusion systematics from mineralized veins at Enyigba, Ameta, Ikwo, Otim Land, and Uburu-Abakaliki, using microthermometry, crush-leach analysis, and Raman spectroscopy. Fluid inclusion microthermometry reveals homogenization temperatures between 99 and 190 °C and salinities of 18.3–22 wt%NaCl + CaCl2, typical of unconformity-related hydrothermal vein systems. Geochemical data indicate the mineralizing fluids resulted from mixing of bittern brines (low Cl/Br), halite-dissolution brines (high Cl/Br), and oilfield brines, as shown by Cl/Br ratios and Rb/Cs values. Microraman spectroscopy suggests the presence of hydrocarbons, supporting the involvement of reduced oilfield brines. These findings point to a complex fluid mixing process, likely driven by crustal-scale faulting during the rifting of the Benue Trough in the context of Pangaea break-up. This research suggests a common ore-forming process for the Nigerian deposits.
{"title":"Unconformity-related fluorite-baryte-base metal mineralization in the Benue Trough, Nigeria: A multifluid origin triggered by the separation of Pangaea","authors":"Benjamin F. Walter , Ndukauba Egesi , Mohsin Raza , Micheal Agbebia , Fadila Adamu , R. Johannes Giebel , Michael A.W. Marks , Emmanuel Chidi Ugbaja , Gregor Markl","doi":"10.1016/j.jafrearsci.2025.105964","DOIUrl":"10.1016/j.jafrearsci.2025.105964","url":null,"abstract":"<div><div>Unconformity-related hydrothermal vein-type deposits are key sources of high-purity fluorite, baryte, and base metals, with occurrences in Nigeria, particularly along the Benue Trough. However, the genesis of the Nigerian deposits is not well understood. This study examines fluid inclusion systematics from mineralized veins at Enyigba, Ameta, Ikwo, Otim Land, and Uburu-Abakaliki, using microthermometry, crush-leach analysis, and Raman spectroscopy. Fluid inclusion microthermometry reveals homogenization temperatures between 99 and 190 °C and salinities of 18.3–22 wt%NaCl + CaCl<sub>2</sub>, typical of unconformity-related hydrothermal vein systems. Geochemical data indicate the mineralizing fluids resulted from mixing of bittern brines (low Cl/Br), halite-dissolution brines (high Cl/Br), and oilfield brines, as shown by Cl/Br ratios and Rb/Cs values. Microraman spectroscopy suggests the presence of hydrocarbons, supporting the involvement of reduced oilfield brines. These findings point to a complex fluid mixing process, likely driven by crustal-scale faulting during the rifting of the Benue Trough in the context of Pangaea break-up. This research suggests a common ore-forming process for the Nigerian deposits.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105964"},"PeriodicalIF":2.2,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787919","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 : 2025-12-05DOI: 10.1016/j.jafrearsci.2025.105955
Ahmed A. Kassem
The Miocene Asl Member in the North October Field, Gulf of Suez Rift, offers a well-exposed case study of syn-rift slope-apron sedimentation, where gravity-driven depositional processes, Syn-depositional faulting, and diagenetic evolution combine to create highly heterogeneous reservoirs. This integrated study synthesizes detailed core facies analysis, petrography analysis, structural interpretation, and dynamic production data to construct a predictive reservoir model linking facies architecture to reservoir performance. The methodology integrates 230 ft of conventional core description, thin-section petrography, SEM imaging, porosity–permeability measurements, and historical production data from three wells (GS172-2, GS183-1, and OCT-J5) to ensure quantitative and reproducible interpretation. Three principal facies associations: Facies A: sand-prone gravity flows, Facies B: heterolithic debris flows and Facies C: carbonate-rich deposits establish a complex stratigraphic framework, vertically partitioned by diagenetic baffles and laterally segmented by active growth faulting. Diagenetic processes, particularly feldspar dissolution and pervasive carbonate cementation, amplify contrasts in reservoir quality, controlling porosity-permeability distributions across facies. Structural and stratigraphic compartmentalization govern distinct pressure regimes and flow unit behavior, reflected in differential production responses between fault blocks. High initial oil production is sustained from clean, sand-prone compartments, while water breakthrough and rapid decline are strongly influenced by intra-reservoir heterogeneity. The Asl Member case study enhances understanding of how sedimentary, diagenetic, and structural factors interact to shape reservoir performance in syn-rift settings, providing a methodological framework applicable to other tectonically active rifted margins. The multi-disciplinary approach presented here offers an effective predictive framework for exploration and development strategies in structurally complex clastic reservoirs worldwide.
{"title":"Reservoir architecture, diagenesis, and compartmentalization in syn-rift gravity-flow systems: Insights from the Gulf of Suez Rift basin","authors":"Ahmed A. Kassem","doi":"10.1016/j.jafrearsci.2025.105955","DOIUrl":"10.1016/j.jafrearsci.2025.105955","url":null,"abstract":"<div><div>The Miocene Asl Member in the North October Field, Gulf of Suez Rift, offers a well-exposed case study of syn-rift slope-apron sedimentation, where gravity-driven depositional processes, Syn-depositional faulting, and diagenetic evolution combine to create highly heterogeneous reservoirs. This integrated study synthesizes detailed core facies analysis, petrography analysis, structural interpretation, and dynamic production data to construct a predictive reservoir model linking facies architecture to reservoir performance. The methodology integrates 230 ft of conventional core description, thin-section petrography, SEM imaging, porosity–permeability measurements, and historical production data from three wells (GS172-2, GS183-1, and OCT-J5) to ensure quantitative and reproducible interpretation. Three principal facies associations: Facies A: sand-prone gravity flows, Facies B: heterolithic debris flows and Facies C: carbonate-rich deposits establish a complex stratigraphic framework, vertically partitioned by diagenetic baffles and laterally segmented by active growth faulting. Diagenetic processes, particularly feldspar dissolution and pervasive carbonate cementation, amplify contrasts in reservoir quality, controlling porosity-permeability distributions across facies. Structural and stratigraphic compartmentalization govern distinct pressure regimes and flow unit behavior, reflected in differential production responses between fault blocks. High initial oil production is sustained from clean, sand-prone compartments, while water breakthrough and rapid decline are strongly influenced by intra-reservoir heterogeneity. The Asl Member case study enhances understanding of how sedimentary, diagenetic, and structural factors interact to shape reservoir performance in syn-rift settings, providing a methodological framework applicable to other tectonically active rifted margins. The multi-disciplinary approach presented here offers an effective predictive framework for exploration and development strategies in structurally complex clastic reservoirs worldwide.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105955"},"PeriodicalIF":2.2,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735045","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}
The Kaiama gold deposit, located within the Proterozoic basement complex of northcentral Nigeria, is hosted predominantly in structurally controlled quartz-sulfide veins emplaced within mylonitized quartzite and talc schist units. The mineralization is spatially associated with NE–SW-trending ductile shear zones, interpreted as subsidiary structures of the regionally extensive Anka–Yauri fault system. While gold occurrences in Nigeria have been widely documented, the origin and evolution of the ore-forming fluids have continued to be a subject of debate. This study integrates fluid inclusion petrography, microthermometric analysis, and stable isotope (δ18O and δD) geochemistry to unravel the physicochemical conditions and fluid sources involved in the mineralization process. Detailed petrographic examination identifies a sulfide assemblage comprising pyrite, galena, chalcopyrite, chalcocite, and sphalerite, with quartz, sericite, and feldspar as the dominant gangue minerals. Fluid inclusion petrography revealed three distinct fluid types: Type I (carbonic aqueous three-phase fluids), Type II (vapour rich biphasic fluids), and Type III (liquid rich biphasic fluids), whose coexistence indicates fluid mixing as a key ore-forming mechanism. Microthermometric measurements yielded homogenization temperatures ranging from 169 °C to 339 °C and salinities between 0.4 and 15.3 wt% NaCl equivalent, consistent with low-to moderate-temperature, moderately saline hydrothermal fluids. Stable isotope compositions of fluid inclusions (δ18O_water = +1.57 ‰ to +7.07 ‰; δD_water = −114 ‰ to −33 ‰) point to a mixed fluid source, involving both metamorphic and meteoric components. Collectively, the results suggest that structurally focused fluid flow and mixing of contrasting fluid sources played a pivotal role in the precipitation of gold at Kaiama.
{"title":"Genesis of Kaiama gold mineralization, northcentral Nigeria: Evidence from fluid inclusion and stable O–H isotope","authors":"Aliyu Ohiani Umaru , Olugbenga Okunlola , Umaru Adamu Danbatta , Yılmaz Demir , Yarsé Brodivier Mavoungou , Brahim Salem-Vall , Hamman Ishaku Kamale","doi":"10.1016/j.jafrearsci.2025.105963","DOIUrl":"10.1016/j.jafrearsci.2025.105963","url":null,"abstract":"<div><div>The Kaiama gold deposit, located within the Proterozoic basement complex of northcentral Nigeria, is hosted predominantly in structurally controlled quartz-sulfide veins emplaced within mylonitized quartzite and talc schist units. The mineralization is spatially associated with NE–SW-trending ductile shear zones, interpreted as subsidiary structures of the regionally extensive Anka–Yauri fault system. While gold occurrences in Nigeria have been widely documented, the origin and evolution of the ore-forming fluids have continued to be a subject of debate. This study integrates fluid inclusion petrography, microthermometric analysis, and stable isotope (δ<sup>18</sup>O and δD) geochemistry to unravel the physicochemical conditions and fluid sources involved in the mineralization process. Detailed petrographic examination identifies a sulfide assemblage comprising pyrite, galena, chalcopyrite, chalcocite, and sphalerite, with quartz, sericite, and feldspar as the dominant gangue minerals. Fluid inclusion petrography revealed three distinct fluid types: Type I (carbonic aqueous three-phase fluids), Type II (vapour rich biphasic fluids), and Type III (liquid rich biphasic fluids), whose coexistence indicates fluid mixing as a key ore-forming mechanism. Microthermometric measurements yielded homogenization temperatures ranging from 169 °C to 339 °C and salinities between 0.4 and 15.3 wt% NaCl equivalent, consistent with low-to moderate-temperature, moderately saline hydrothermal fluids. Stable isotope compositions of fluid inclusions (δ<sup>18</sup>O_water = +1.57 ‰ to +7.07 ‰; δD_water = −114 ‰ to −33 ‰) point to a mixed fluid source, involving both metamorphic and meteoric components. Collectively, the results suggest that structurally focused fluid flow and mixing of contrasting fluid sources played a pivotal role in the precipitation of gold at Kaiama.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105963"},"PeriodicalIF":2.2,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684001","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 : 2025-12-04DOI: 10.1016/j.jafrearsci.2025.105954
Kemiso Tshwenyego , James King , Adrian R. Muxworthy , Liang Qi , Moikwathai Moidaki
The geomagnetic field including its intensity is poorly constrained during the Proterozoic era (2500–541 Ma). Understanding geomagnetic field behaviour during this long-time interval is key to understand the evolution of the Earth including dating the age of the Earth's inner core nucleation. Palaeointensity experiments suggest low magnetic field intensities during the Palaeoproterozoic era between (2500–1500 Ma). To address this issue, we present palaeodirectional and palaeointensity results conducted on three previously dated Palaeoproterozoic localities in Botswana: 1) the Moshaneng Complex gabbros (2054 ± 2 Ma), 2) the Moshaneng dolerite dykes (1927 ± 1.5 Ma), and 3) the Pilanesberg dolerite dykes (1347 ± 97 Ma). Virtual geomagnetic poles were obtained from all three localities. Only the Moshaneng dolerite dyke yielded a virtual dipole moment (VDM) of 2.4 ± 0.4 × 1022Am2 from the three studied sites, which is consistent with a dipole low during the Palaeoproterozoic era. The results show that during the Palaeoproterozoic era, there was low VDM recorded which is similar to other values obtained in similarly aged Palaeoproterozoic studies.
{"title":"Palaeomagnetic investigation of Palaeoproterozoic dykes from Botswana","authors":"Kemiso Tshwenyego , James King , Adrian R. Muxworthy , Liang Qi , Moikwathai Moidaki","doi":"10.1016/j.jafrearsci.2025.105954","DOIUrl":"10.1016/j.jafrearsci.2025.105954","url":null,"abstract":"<div><div>The geomagnetic field including its intensity is poorly constrained during the Proterozoic era (2500–541 Ma). Understanding geomagnetic field behaviour during this long-time interval is key to understand the evolution of the Earth including dating the age of the Earth's inner core nucleation. Palaeointensity experiments suggest low magnetic field intensities during the Palaeoproterozoic era between (2500–1500 Ma). To address this issue, we present palaeodirectional and palaeointensity results conducted on three previously dated Palaeoproterozoic localities in Botswana: 1) the Moshaneng Complex gabbros (2054 ± 2 Ma), 2) the Moshaneng dolerite dykes (1927 ± 1.5 Ma), and 3) the Pilanesberg dolerite dykes (1347 ± 97 Ma). Virtual geomagnetic poles were obtained from all three localities. Only the Moshaneng dolerite dyke yielded a virtual dipole moment (VDM) of 2.4 ± 0.4 × 10<sup>22</sup>Am<sup>2</sup> from the three studied sites, which is consistent with a dipole low during the Palaeoproterozoic era. The results show that during the Palaeoproterozoic era, there was low VDM recorded which is similar to other values obtained in similarly aged Palaeoproterozoic studies.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 105954"},"PeriodicalIF":2.2,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979501","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 : 2025-12-03DOI: 10.1016/j.jafrearsci.2025.105953
Zafer Aslan , M. Selman Aydoğan , Y. Kağan Kadıoğlu , Özcan Yi̇ği̇t
The Afyon Zone basement, regarded as part of the northern passive margin of Gondwana during the Late Paleozoic, comprises Paleozoic quartz-muscovite schists and phyllites intruded by Carboniferous metaplutonic bodies. The Triassic cover rocks consist of metadacite and ore-bearing metabasic. The plutonic assemblage in the area is represented by two principal intrusive phases: (i) metagranite porphyry and (ii) metagranite. Of these, age of the metagranite porphyry unit was determined to be 311.1 ± 5.0 Ma, and that of the metagranite to be 309.3 ± 1.9 Ma, using the U-Pb zircon SHRIMP method. Mineral chemistry analyses indicate that the temperature of the plagioclase in the metaplutonic and schist rocks is below 600 °C. The muscovite mineral in the schists is of the muscovite-ferromuscovite type and is crustal in origin.
The metaplutonic suites correspond to S-type, peraluminous granitoids with high-K calc-alkaline affinities. Trace element distribution diagrams show enrichment in large ion radius lithophile elements (LILE; K, Rb, Th and U), while some high-field-strength elements (HFSE; Nb, Y and Sr) show depletion. The rare earth element distributions, are concave in shape (average LaN/LuN = 4–23) and exhibit a slight negative Eu anomaly (Eu/Eu∗ = 0.40–1.06). Both plutons are tectonically associated with a volcanic arc and formed within the continental crust. The primary magmas of the metaplutonic rocks formed through magmatic interaction with partially melted metapelitic rocks in the lithospheric mantle and the lower continental crust. Metamorphic basement rocks are high in potassium and exhibit a shoshonitic character. The average primary 87Sr/86Sr for metaplutonic rocks is around 0.720, while the 143Nd/144Nd values range from 0.512139 to 0.512257.
These values suggest that the source area from which the plutons was originated from enriched-mantle. Accordingly, the Middle Carboniferous metagranitic magmatism in the Afyon Zone is interpreted to have developed within a continental volcanic arc setting associated with the southward subduction and progressive closure of the Paleotethys Ocean along the northern margin of Gondwana.
{"title":"U-Pb zircon geochronology, Sr-Nd isotope geochemistry and petrology of Carboniferous granitic rocks in Afyon Zone (NW Türkiye)","authors":"Zafer Aslan , M. Selman Aydoğan , Y. Kağan Kadıoğlu , Özcan Yi̇ği̇t","doi":"10.1016/j.jafrearsci.2025.105953","DOIUrl":"10.1016/j.jafrearsci.2025.105953","url":null,"abstract":"<div><div>The Afyon Zone basement, regarded as part of the northern passive margin of Gondwana during the Late Paleozoic, comprises Paleozoic quartz-muscovite schists and phyllites intruded by Carboniferous metaplutonic bodies. The Triassic cover rocks consist of metadacite and ore-bearing metabasic. The plutonic assemblage in the area is represented by two principal intrusive phases: (i) metagranite porphyry and (ii) metagranite. Of these, age of the metagranite porphyry unit was determined to be 311.1 ± 5.0 Ma, and that of the metagranite to be 309.3 ± 1.9 Ma, using the U-Pb zircon SHRIMP method. Mineral chemistry analyses indicate that the temperature of the plagioclase in the metaplutonic and schist rocks is below 600 °C. The muscovite mineral in the schists is of the muscovite-ferromuscovite type and is crustal in origin.</div><div>The metaplutonic suites correspond to S-type, peraluminous granitoids with high-K calc-alkaline affinities. Trace element distribution diagrams show enrichment in large ion radius lithophile elements (LILE; K, Rb, Th and U), while some high-field-strength elements (HFSE; Nb, Y and Sr) show depletion. The rare earth element distributions, are concave in shape (average La<sub>N</sub>/Lu<sub>N</sub> = 4–23) and exhibit a slight negative Eu anomaly (Eu/Eu∗ = 0.40–1.06). Both plutons are tectonically associated with a volcanic arc and formed within the continental crust. The primary magmas of the metaplutonic rocks formed through magmatic interaction with partially melted metapelitic rocks in the lithospheric mantle and the lower continental crust. Metamorphic basement rocks are high in potassium and exhibit a shoshonitic character. The average primary <sup>87</sup>Sr/<sup>86</sup>Sr for metaplutonic rocks is around 0.720, while the <sup>143</sup>Nd/<sup>144</sup>Nd values range from 0.512139 to 0.512257.</div><div>These values suggest that the source area from which the plutons was originated from enriched-mantle. Accordingly, the Middle Carboniferous metagranitic magmatism in the Afyon Zone is interpreted to have developed within a continental volcanic arc setting associated with the southward subduction and progressive closure of the Paleotethys Ocean along the northern margin of Gondwana.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105953"},"PeriodicalIF":2.2,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684000","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 : 2025-12-02DOI: 10.1016/j.jafrearsci.2025.105950
Yakup Abdik , Neslihan Ocakoğlu , Bülent Kaypak
Stratigraphic and structural features of the Aşkale-Pasinler-Horasan basins located within the borders of Erzurum Province in the Eastern Anatolia Region were investigated to depths of approximately 3–4 km by evaluating 1300 km of multichannel 2D seismic reflection data and three boreholes collected in the region between 1977 and 2001. A total of eight seismic units ranging from Mesozoic to Plio-Quaternary were interpreted within the basins. Seismic stratigraphy and structural features show that Aşkale, Erzurum, Pasinler and Horasan basins were initiated and began to shape during the tectonic regime extending from the Mesozoic to the Late Miocene, with possible strong compression, rapid uplift and long-term erosion processes, respectively. Particularly, Mesozoic Ophiolites play an important role to form these basins and ridges geometry at present. Because both the ophiolites are widespread under the Neogene deposits of basins and the wells drilled in this region penetrate into the ophiolitic melange by cutting through the Neogene deposits. The Late Miocene erosional surface is overlain by very gently accumulated horizontal sediments deposited from the Upper Miocene to present within the basins (∼2.0 km thick). These interpretations on the seismic sections indicated that compressional tectonic regime has remarkably left the region after Late Miocene. However, within the Plio-Quaternary sediment strata, several active N-S to NE-SW oriented strike-slip faults with reverse components, WNW-ESE oriented strike-slip faults and ENE-WSW oriented positive flower structures were mapped. These faults are interpreted as Plio Quaternary in age, which are responsible for the recent deformation in the basins and their surrounding region. The major of them either overlap with the previously mapped active Aşkale, Erzurum and Pasinler fault zones in the region or form their continuations within the basin. These compressional strike-slip faults border the basins and elevate the ridges to the north and to the south. Thus, they form ramp basins structures in the Aşkale, Pasinler and Horasan. In addition, newly mapped strike-slip faults and positive flower structures squeeezed the basin deposits within the Aşkale, Erzurum and Horasan basins. It is seen that the basins and ridges have recently been under a compressional strike-slip tectonics. The quantitative analysis of earthquake focal mechanisms supports our fault orientation and character. It reveals an approximately NNE-SSW maximum horizontal stress (SHmax) orientation within these basins which is primarily controlled by the continental collision between the Arabian and Eurasian plates.
{"title":"Analysis of the active tectonics of the Aşkale-Pasinler-Horasan Basins (Eastern Anatolia) using multichannel seismic reflection and stratigraphic data","authors":"Yakup Abdik , Neslihan Ocakoğlu , Bülent Kaypak","doi":"10.1016/j.jafrearsci.2025.105950","DOIUrl":"10.1016/j.jafrearsci.2025.105950","url":null,"abstract":"<div><div>Stratigraphic and structural features of the Aşkale-Pasinler-Horasan basins located within the borders of Erzurum Province in the Eastern Anatolia Region were investigated to depths of approximately 3–4 km by evaluating 1300 km of multichannel 2D seismic reflection data and three boreholes collected in the region between 1977 and 2001. A total of eight seismic units ranging from Mesozoic to Plio-Quaternary were interpreted within the basins. Seismic stratigraphy and structural features show that Aşkale, Erzurum, Pasinler and Horasan basins were initiated and began to shape during the tectonic regime extending from the Mesozoic to the Late Miocene, with possible strong compression, rapid uplift and long-term erosion processes, respectively. Particularly, Mesozoic Ophiolites play an important role to form these basins and ridges geometry at present. Because both the ophiolites are widespread under the Neogene deposits of basins and the wells drilled in this region penetrate into the ophiolitic melange by cutting through the Neogene deposits. The Late Miocene erosional surface is overlain by very gently accumulated horizontal sediments deposited from the Upper Miocene to present within the basins (∼2.0 km thick). These interpretations on the seismic sections indicated that compressional tectonic regime has remarkably left the region after Late Miocene. However, within the Plio-Quaternary sediment strata, several active N-S to NE-SW oriented strike-slip faults with reverse components, WNW-ESE oriented strike-slip faults and ENE-WSW oriented positive flower structures were mapped. These faults are interpreted as Plio Quaternary in age, which are responsible for the recent deformation in the basins and their surrounding region. The major of them either overlap with the previously mapped active Aşkale, Erzurum and Pasinler fault zones in the region or form their continuations within the basin. These compressional strike-slip faults border the basins and elevate the ridges to the north and to the south. Thus, they form ramp basins structures in the Aşkale, Pasinler and Horasan. In addition, newly mapped strike-slip faults and positive flower structures squeeezed the basin deposits within the Aşkale, Erzurum and Horasan basins. It is seen that the basins and ridges have recently been under a compressional strike-slip tectonics. The quantitative analysis of earthquake focal mechanisms supports our fault orientation and character. It reveals an approximately NNE-SSW maximum horizontal stress (SHmax) orientation within these basins which is primarily controlled by the continental collision between the Arabian and Eurasian plates.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105950"},"PeriodicalIF":2.2,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735047","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 : 2025-12-02DOI: 10.1016/j.jafrearsci.2025.105952
Aziz Hayati , Hicham EL Asmi , Lahcen Gourari , Mohamed Benabbou , Imad EL Yakouti , Aziza Lyazidi , Mohammed EL Aoufir , Meryem Redouane , Khalil Azennoud , Yassine Ait Brahim
Quaternary calcretes in the Oued Nja Valley, located in the Saïss Basin, Morocco, provide an exceptional record of North African palaeoenvironmental dynamics. This multidisciplinary study, integrating sedimentological, mineralogical and diagenetic analyses, identifies nine calcrete types: root-related, nodular, laminar, massive, conglomeratic, powdery, encrusted, and fracture-filling. These formations reflect complex pedogenic and hydrochemical processes. Pedogenic calcretes, organized in distinct horizons, exhibit both biogenic (rhizoliths, pisoliths, calcified filaments) and abiotic (laminations, dense microfabrics) structures, indicating soil-atmosphere interactions under semi-arid to sub-humid climatic conditions. In contrast, hydrochemical calcretes, formed in shallow aquifers, are characterized by sparitic cements, floating grains and circumgranular cracks, suggesting rapid cementation under arid conditions. Analyses reveal a dominance of calcite (57.79–84.42 % CaCO3) alongside siliciclastic interbeds, pointing to aeolian inputs during dry periods. The genesis and evolution of these calcretes are modulated by the Liassic carbonate substrate, local hydrology, biological activity and tectonics of the South Rifian Corridor (NE-SW, NS and NW-SE faults), recording environmental oscillations between humid phases with dense vegetation and arid periods dominated by evaporation. Compared to Mediterranean calcretes, they are distinguished by their abundance of biogenic structures and proximity to faulted zones. The findings highlight calcretes as key palaeoclimatic and geological markers, with significant implications for sustainable water resource management: massive facies indicate areas prone to aridification, while root-related facies may signal potential for enhanced groundwater recharge. Future geochemical and microstructural investigations could refine these models, enhancing regional palaeoenvironmental reconstructions.
{"title":"Typology, palaeoenvironmental significance and palaeoclimatic implications of calcretes in the Oued Nja Valley (South Rifian Corridor, Morocco)","authors":"Aziz Hayati , Hicham EL Asmi , Lahcen Gourari , Mohamed Benabbou , Imad EL Yakouti , Aziza Lyazidi , Mohammed EL Aoufir , Meryem Redouane , Khalil Azennoud , Yassine Ait Brahim","doi":"10.1016/j.jafrearsci.2025.105952","DOIUrl":"10.1016/j.jafrearsci.2025.105952","url":null,"abstract":"<div><div>Quaternary calcretes in the Oued Nja Valley, located in the Saïss Basin, Morocco, provide an exceptional record of North African palaeoenvironmental dynamics. This multidisciplinary study, integrating sedimentological, mineralogical and diagenetic analyses, identifies nine calcrete types: root-related, nodular, laminar, massive, conglomeratic, powdery, encrusted, and fracture-filling. These formations reflect complex pedogenic and hydrochemical processes. Pedogenic calcretes, organized in distinct horizons, exhibit both biogenic (rhizoliths, pisoliths, calcified filaments) and abiotic (laminations, dense microfabrics) structures, indicating soil-atmosphere interactions under semi-arid to sub-humid climatic conditions. In contrast, hydrochemical calcretes, formed in shallow aquifers, are characterized by sparitic cements, floating grains and circumgranular cracks, suggesting rapid cementation under arid conditions. Analyses reveal a dominance of calcite (57.79–84.42 % CaCO<sub>3</sub>) alongside siliciclastic interbeds, pointing to aeolian inputs during dry periods. The genesis and evolution of these calcretes are modulated by the Liassic carbonate substrate, local hydrology, biological activity and tectonics of the South Rifian Corridor (NE-SW, NS and NW-SE faults), recording environmental oscillations between humid phases with dense vegetation and arid periods dominated by evaporation. Compared to Mediterranean calcretes, they are distinguished by their abundance of biogenic structures and proximity to faulted zones. The findings highlight calcretes as key palaeoclimatic and geological markers, with significant implications for sustainable water resource management: massive facies indicate areas prone to aridification, while root-related facies may signal potential for enhanced groundwater recharge. Future geochemical and microstructural investigations could refine these models, enhancing regional palaeoenvironmental reconstructions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105952"},"PeriodicalIF":2.2,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735100","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 : 2025-11-30DOI: 10.1016/j.jafrearsci.2025.105951
Uwezo Frank Mao , Benatus Norbert Mvile , Mahamuda Abu , Emmanuel Sulungu
The Dodoma region of central Tanzania is a semi-arid climatic region underlain by crystalline basement rocks. Like other semi-arid zones, it faces acute groundwater scarcity due to erratic rainfall and over-extraction driven by population growth and industrialization. This study applies an integrated geophysical and geological approach to delineate groundwater resources and assess structural controls on their occurrence. By combining airborne gravity and magnetic data with geological mapping and borehole information, key groundwater-bearing structures such as faults, fractures, shear zones, and dykes were identified. Areas with low-density and low-magnetic anomalies, particularly in the southeastern and central parts, coincide with structurally deformed zones that enhance porosity and permeability. Topographic depressions and fault intersections were also found to facilitate recharge. The results confirm that a multidisciplinary framework improves the reliability of aquifer characterization in crystalline terrains. This approach provides a practical, cost-effective solution for groundwater exploration in semi-arid regions, supporting sustainable water resource management amid rising demand.
{"title":"Integrated geophysical and geological assessment of groundwater occurrence in the Dodoma region, central Tanzania","authors":"Uwezo Frank Mao , Benatus Norbert Mvile , Mahamuda Abu , Emmanuel Sulungu","doi":"10.1016/j.jafrearsci.2025.105951","DOIUrl":"10.1016/j.jafrearsci.2025.105951","url":null,"abstract":"<div><div>The Dodoma region of central Tanzania is a semi-arid climatic region underlain by crystalline basement rocks. Like other semi-arid zones, it faces acute groundwater scarcity due to erratic rainfall and over-extraction driven by population growth and industrialization. This study applies an integrated geophysical and geological approach to delineate groundwater resources and assess structural controls on their occurrence. By combining airborne gravity and magnetic data with geological mapping and borehole information, key groundwater-bearing structures such as faults, fractures, shear zones, and dykes were identified. Areas with low-density and low-magnetic anomalies, particularly in the southeastern and central parts, coincide with structurally deformed zones that enhance porosity and permeability. Topographic depressions and fault intersections were also found to facilitate recharge. The results confirm that a multidisciplinary framework improves the reliability of aquifer characterization in crystalline terrains. This approach provides a practical, cost-effective solution for groundwater exploration in semi-arid regions, supporting sustainable water resource management amid rising demand.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105951"},"PeriodicalIF":2.2,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145659070","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 : 2025-11-29DOI: 10.1016/j.jafrearsci.2025.105949
Mohammed Laiche , Youssef Drissi , Saïd Hinaje , Driss Yaagoub , Mohamed El Fartati , Youssef Ouahzizi , Anas Laksir
Copper mineralization in the Moroccan Atlas Mountains remains insufficiently characterized, particularly within the Middle Atlas, where the metallogenic framework and structural controls are still poorly constrained. Previous research has mainly focused on the better-documented Anti-Atlas and High Atlas provinces, leaving a significant knowledge gap concerning the geological and tectonic factors governing copper deposition in this orogenic belt. To address this gap, the present study applies an integrated and reproducible methodological framework that combines remote sensing analysis, structural interpretation, and field-based geological validation to evaluate the metallogenic potential of the Middle Atlas. Principal Component Analysis (PCA) was performed on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data to extract major structural lineaments, while spectral band ratio techniques were employed to map hydrothermal alteration zones indicative of copper mineralization, including sericitic, argillic, propylitic, and ferruginous alterations. Through this integrated methodological framework, favorable zones for significant mineralization were accurately delineated, primarily along major tectonic structures. Field investigations confirmed the presence of copper mineralization occurring in two main morphological types: (i) vein-type mineralization hosted within fault zones and tension gashes, and (ii) stratiform mineralization within sedimentary layers interbedded with Triassic doleritic basalt flows. Structural analysis indicated that the mineralization is spatially and temporally associated with two principal tectonic phases: (i) a NW–SE to WNW–ESE extensional regime corresponding to the main mineralizing phase, and (ii) a NW–SE compressional phase responsible for the development of NNE–SSW sinistral and WNW–ESE dextral strike-slip faults, which locally remobilized earlier mineralized structures together with manganese occurrences. These tectonic activities resulted in the deformation of pre-existing mineralized structures, forming NW–SE-oriented tension gashes filled with quartz and traces of malachite. Petrographic and mineralogical analyses reveal a paragenetic sequence dominated by copper sulfides (chalcopyrite, chalcocite, bornite, and covellite), followed by secondary copper carbonates (malachite, azurite) and late-stage iron oxides (hematite, limonite), indicating a complex hydrothermal-supergene evolution. These results provide concrete insights to effectively guide mineral exploration in the ug.
{"title":"Identification, genesis, and structural-gitological analysis of copper mineralization in the Middle Atlas, Morocco: integrating remote sensing with field investigations","authors":"Mohammed Laiche , Youssef Drissi , Saïd Hinaje , Driss Yaagoub , Mohamed El Fartati , Youssef Ouahzizi , Anas Laksir","doi":"10.1016/j.jafrearsci.2025.105949","DOIUrl":"10.1016/j.jafrearsci.2025.105949","url":null,"abstract":"<div><div>Copper mineralization in the Moroccan Atlas Mountains remains insufficiently characterized, particularly within the Middle Atlas, where the metallogenic framework and structural controls are still poorly constrained. Previous research has mainly focused on the better-documented Anti-Atlas and High Atlas provinces, leaving a significant knowledge gap concerning the geological and tectonic factors governing copper deposition in this orogenic belt. To address this gap, the present study applies an integrated and reproducible methodological framework that combines remote sensing analysis, structural interpretation, and field-based geological validation to evaluate the metallogenic potential of the Middle Atlas. Principal Component Analysis (PCA) was performed on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data to extract major structural lineaments, while spectral band ratio techniques were employed to map hydrothermal alteration zones indicative of copper mineralization, including sericitic, argillic, propylitic, and ferruginous alterations. Through this integrated methodological framework, favorable zones for significant mineralization were accurately delineated, primarily along major tectonic structures. Field investigations confirmed the presence of copper mineralization occurring in two main morphological types: (i) vein-type mineralization hosted within fault zones and tension gashes, and (ii) stratiform mineralization within sedimentary layers interbedded with Triassic doleritic basalt flows. Structural analysis indicated that the mineralization is spatially and temporally associated with two principal tectonic phases: (i) a NW–SE to WNW–ESE extensional regime corresponding to the main mineralizing phase, and (ii) a NW–SE compressional phase responsible for the development of NNE–SSW sinistral and WNW–ESE dextral strike-slip faults, which locally remobilized earlier mineralized structures together with manganese occurrences. These tectonic activities resulted in the deformation of pre-existing mineralized structures, forming NW–SE-oriented tension gashes filled with quartz and traces of malachite. Petrographic and mineralogical analyses reveal a paragenetic sequence dominated by copper sulfides (chalcopyrite, chalcocite, bornite, and covellite), followed by secondary copper carbonates (malachite, azurite) and late-stage iron oxides (hematite, limonite), indicating a complex hydrothermal-supergene evolution. These results provide concrete insights to effectively guide mineral exploration in the ug.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105949"},"PeriodicalIF":2.2,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690723","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 : 2025-11-27DOI: 10.1016/j.jafrearsci.2025.105948
Alsir A.A. Alkhaleefa , Talha M. Yousif , Musab A.A. Hassan , Khalid A. Elsayed Zeinelabdein
Talc deposits found in the southwestern Fodikwan area of northeastern Sudan exhibit potential economic significance; nevertheless, their geological context, geochemical characteristics, and genesis remain inadequately defined. This study aims to elucidate the origin and formation mechanisms of these deposits, thereby facilitating the development of more effective exploration strategies. An integrated methodology was employed, comprising detailed geological mapping, petrographic investigations, and mineralogical and geochemical assessments utilizing X-ray diffraction (XRD) and X-ray fluorescence (XRF). The study area is characterized by basement rocks comprising a volcanic-sedimentary sequence that has been metamorphosed in the greenschist facies and intruded by syn-to late-orogenic microgranodiorite. Field and petrographic observations indicate that unaltered dolomitic marble predominates in areas distant from microgranodiorite contacts. Conversely, the contact zone between dolomitic marble and microgranodiorite presents a conducive environment for talc mineralization. Geochemical analyses reveal that SiO2 and MgO are the dominant constituents, whereas CaO exhibits a decreasing trend as SiO2 increases, reflecting the metamorphism of dolomitic marble into talc. Additionally, a noteworthy depletion of Al, La, Th, Cr, Ni, and Co in talc ores is inconsistent with a mafic or ultramafic protolith. The results suggest that the silica necessary for talc formation was derived from the adjacent microgranodiorite, with dolomitic marble acting as the primary protolith. Furthermore, the presence of quartz within the dolomitic marble may have provided the necessary silica for the formation of talc. This evidence supports a genetic model of contact metasomatism and has significant implications for regional talc exploration, particularly targeting the marble-microgranodiorite contact zones.
{"title":"Talc mineralization in the SW Fodikwan area, Red Sea Hills, NE Sudan: Geological and geochemical constraints","authors":"Alsir A.A. Alkhaleefa , Talha M. Yousif , Musab A.A. Hassan , Khalid A. Elsayed Zeinelabdein","doi":"10.1016/j.jafrearsci.2025.105948","DOIUrl":"10.1016/j.jafrearsci.2025.105948","url":null,"abstract":"<div><div>Talc deposits found in the southwestern Fodikwan area of northeastern Sudan exhibit potential economic significance; nevertheless, their geological context, geochemical characteristics, and genesis remain inadequately defined. This study aims to elucidate the origin and formation mechanisms of these deposits, thereby facilitating the development of more effective exploration strategies. An integrated methodology was employed, comprising detailed geological mapping, petrographic investigations, and mineralogical and geochemical assessments utilizing X-ray diffraction (XRD) and X-ray fluorescence (XRF). The study area is characterized by basement rocks comprising a volcanic-sedimentary sequence that has been metamorphosed in the greenschist facies and intruded by syn-to late-orogenic microgranodiorite. Field and petrographic observations indicate that unaltered dolomitic marble predominates in areas distant from microgranodiorite contacts. Conversely, the contact zone between dolomitic marble and microgranodiorite presents a conducive environment for talc mineralization. Geochemical analyses reveal that SiO<sub>2</sub> and MgO are the dominant constituents, whereas CaO exhibits a decreasing trend as SiO<sub>2</sub> increases, reflecting the metamorphism of dolomitic marble into talc. Additionally, a noteworthy depletion of Al, La, Th, Cr, Ni, and Co in talc ores is inconsistent with a mafic or ultramafic protolith. The results suggest that the silica necessary for talc formation was derived from the adjacent microgranodiorite, with dolomitic marble acting as the primary protolith. Furthermore, the presence of quartz within the dolomitic marble may have provided the necessary silica for the formation of talc. This evidence supports a genetic model of contact metasomatism and has significant implications for regional talc exploration, particularly targeting the marble-microgranodiorite contact zones.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105948"},"PeriodicalIF":2.2,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690725","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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