Pub Date : 2025-11-19DOI: 10.1016/j.jafrearsci.2025.105939
Orabi H. Orabi , Saeedeh Senemari
The Campanian/Maastrichtian boundary in Gebel Mukattab is marked by the first appearance of flaring heterohelicids with multiple chambers (e.g., Planoglobulina), where the last appearance of Aspidolithus parcus constrictus in zone CC23 further marks the Campanian–Maastrichtian boundary in the eastern Tethys.
Oxygen-depleted conditions are inferred from the abundance of Heterohelix species, especially in zones CF8b and CF5a. The dominance of double-keeled foraminifera like G. aegyptiaca indicates a late Campanian transgressive event. The biostratigraphic study of the Mukattab section reveals four key bioevents in the late Campanian–Maastrichtian sequence: (1) the G. aegyptiaca Zone above Globotruncanella havanensis, marking the Late Campanian Event (LCE); (2) R. rotundata (CF7a) and Planoglobulina acervulinoides (CF7c), aligned with the Campanian–Maastrichtian Boundary Event (CMBE); (3) C. contusa (CF6), associated with the Mid-Maastrichtian Event (MME); and (4) the CF1 zone, indicating the Late Maastrichtian Event (LME) near the K/Pg boundary.
{"title":"Utilizing planktic foraminifera and calcareous nannofossils to identify geological events of the Late Cretaceous in West-Central Sinai, Egypt","authors":"Orabi H. Orabi , Saeedeh Senemari","doi":"10.1016/j.jafrearsci.2025.105939","DOIUrl":"10.1016/j.jafrearsci.2025.105939","url":null,"abstract":"<div><div>The Campanian/Maastrichtian boundary in Gebel Mukattab is marked by the first appearance of flaring heterohelicids with multiple chambers (e.g., <em>Planoglobulina</em>), where the last appearance of <em>Aspidolithus parcus constrictus</em> in zone CC23 further marks the Campanian–Maastrichtian boundary in the eastern Tethys.</div><div>Oxygen-depleted conditions are inferred from the abundance of <em>Heterohelix</em> species, especially in zones CF8b and CF5a. The dominance of double-keeled foraminifera like <em>G. aegyptiaca</em> indicates a late Campanian transgressive event. The biostratigraphic study of the Mukattab section reveals four key bioevents in the late Campanian–Maastrichtian sequence: (1) the <em>G. aegyptiaca</em> Zone above <em>Globotruncanella havanensis</em>, marking the Late Campanian Event (LCE); (2) <em>R. rotundata</em> (CF7a) and <em>Planoglobulina acervulinoides</em> (CF7c), aligned with the Campanian–Maastrichtian Boundary Event (CMBE); (3) <em>C. contusa</em> (CF6), associated with the Mid-Maastrichtian Event (MME); and (4) the CF1 zone, indicating the Late Maastrichtian Event (LME) near the K/Pg boundary.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105939"},"PeriodicalIF":2.2,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621209","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 : 2025-11-19DOI: 10.1016/j.jafrearsci.2025.105941
Geraldine Chibuzor Anukwu, Daniel Obi-Enadhuze
The University of Lagos is experiencing rapid infrastructure expansion to accommodate its growing student population. However, evidence of structural failures in some buildings has highlighted the need for better understanding of the subsurface and its response to seismic activation. This study applies the Horizontal-to-Vertical Spectral Ratio (HVSR) and Multichannel Analysis of Surface Waves (MASW) techniques at 17 sites across the institution to characterise subsurface conditions, which are critical for infrastructural stability and the assessment of site effects. The findings show notable spatial variation in shear-wave velocity (Vs) across the study area, with velocity inversions at certain sites, suggesting these areas are susceptible to differential settlement and seismic wave amplification. The fundamental frequency (f0) ranges from 0.7 to 1.84 Hz, while the impedance contrast (A0) varies between 1.4 and 8.17. The seismic vulnerability index (Kg) spans values from 1.85 to 55.62, and the depth to the competent layer ranges from 18.61 to 86.53 m. According to Kanai's (1983) classification, the subsurface conditions are predominantly Type II and III, characterised by soft soil, sand, and sandy clay - findings that are consistent with borehole log data. Spatial distribution maps of the estimated parameters identify the north-central sector as the most vulnerable to structural failure under seismic or vibrational loading, whilst the northern and eastern sectors are associated with the greatest depths to competent layers. These findings provide essential subsurface parameters to assess the subsurface condition at the campus, mitigating structural risks, and supporting safe urban development.
{"title":"Assessment of subsurface conditions and seismic site effects using the HVSR and MASW techniques at the University of Lagos, Akoka campus southwestern Nigeria","authors":"Geraldine Chibuzor Anukwu, Daniel Obi-Enadhuze","doi":"10.1016/j.jafrearsci.2025.105941","DOIUrl":"10.1016/j.jafrearsci.2025.105941","url":null,"abstract":"<div><div>The University of Lagos is experiencing rapid infrastructure expansion to accommodate its growing student population. However, evidence of structural failures in some buildings has highlighted the need for better understanding of the subsurface and its response to seismic activation. This study applies the Horizontal-to-Vertical Spectral Ratio (HVSR) and Multichannel Analysis of Surface Waves (MASW) techniques at 17 sites across the institution to characterise subsurface conditions, which are critical for infrastructural stability and the assessment of site effects. The findings show notable spatial variation in shear-wave velocity (Vs) across the study area, with velocity inversions at certain sites, suggesting these areas are susceptible to differential settlement and seismic wave amplification. The fundamental frequency (f0) ranges from 0.7 to 1.84 Hz, while the impedance contrast (A0) varies between 1.4 and 8.17. The seismic vulnerability index (Kg) spans values from 1.85 to 55.62, and the depth to the competent layer ranges from 18.61 to 86.53 m. According to Kanai's (1983) classification, the subsurface conditions are predominantly Type II and III, characterised by soft soil, sand, and sandy clay - findings that are consistent with borehole log data. Spatial distribution maps of the estimated parameters identify the north-central sector as the most vulnerable to structural failure under seismic or vibrational loading, whilst the northern and eastern sectors are associated with the greatest depths to competent layers. These findings provide essential subsurface parameters to assess the subsurface condition at the campus, mitigating structural risks, and supporting safe urban development.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105941"},"PeriodicalIF":2.2,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690746","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}
At the NE edge of the Saghro inlier, the Tassafte mining district represents a promising area to understand the Ag-Hg-Cu mineralization history of the Anti-Atlas belt. The area is located at the Ediacaran-Cambrian transition, where the ore mineralized bodies are hosted within Ediacaran volcano-sedimentary succession of the Ouarzazate Group and also continue within the Cambrian sedimentary sequences. Ore bodies occur in E-W striking structures, ranging from N80° to N120°, which dip 50°–80° to the south and rarely to the north. Mineralization is controlled by two tectonic stages within the E-W trending structures: a) right lateral shearing, syn-kinematic with centimetric quartz veins (QzII); and b) left lateral movement syn-kinematic with barite and calcite veins. Ore microscopy investigation illustrates a multistage ore including; i) the first stage, represented by microcrystalline quartz (QzI) and euhedral pyrite crystals, arsenopyrite and rare cobaltite crystals are also recognized; ii) the second stage which represents the main ore stage in which the most important Ag and Cu were deposited. It is represented by coarse geodic quartz (QzII), associated with chalcopyrite that occurs in veinlets. In addition, rare galena and sphalerite are also observed. This is followed by chalcocite which exhibits tiny veins and also replacing the chalcopyrite. The silver mineralization occurs in minute veins and in the corrosion zone, replacing the preexisting sulfide minerals. Silver mineralization comprises Ag-sulfosalt, Ag-sulfide, Ag-Hg amalgam and rare native silver; iii) centimetric veins of barite and carbonate, followed by zonal quartz (QzIII) which is associated with second generation of chalcopyrite, galena and also rare sphalerite; and iv) supergene alteration stage.
The Tassafte mining area shares several common points with other Ag-Hg ore deposits in the Anti-Atlas. These points comprise comparable Ediacaran volcanic host rocks with a young Cambrian host rocks in The Tassafte area, E-W trending ore veins, and also analogous ore mineralogy. The mineralization studied here are related to post Cambrian tectonism and assumed likely associated with Variscan and Mesozoic tectonic events.
{"title":"Multistage Ag-Hg-Cu mineralization hosted in Ediacaran-Cambrian rocks at the Tassafte mining district, NE edge of the Saghro inlier (eastern Anti-Atlas, Morocco): structural controls and ore textures","authors":"Zakarya Yajioui , Lakhlifi Badra , Alexandre Lima , Sabine Gilbricht , Brahim Karaoui , Amar Karaoui , Abdelkader Mahmoudi","doi":"10.1016/j.jafrearsci.2025.105936","DOIUrl":"10.1016/j.jafrearsci.2025.105936","url":null,"abstract":"<div><div>At the NE edge of the Saghro inlier, the Tassafte mining district represents a promising area to understand the Ag-Hg-Cu mineralization history of the Anti-Atlas belt. The area is located at the Ediacaran-Cambrian transition, where the ore mineralized bodies are hosted within Ediacaran volcano-sedimentary succession of the Ouarzazate Group and also continue within the Cambrian sedimentary sequences. Ore bodies occur in E-W striking structures, ranging from N80° to N120°, which dip 50°–80° to the south and rarely to the north. Mineralization is controlled by two tectonic stages within the E-W trending structures: a) right lateral shearing, syn-kinematic with centimetric quartz veins (QzII); and b) left lateral movement syn-kinematic with barite and calcite veins. Ore microscopy investigation illustrates a multistage ore including; i) the first stage, represented by microcrystalline quartz (QzI) and euhedral pyrite crystals, arsenopyrite and rare cobaltite crystals are also recognized; ii) the second stage which represents the main ore stage in which the most important Ag and Cu were deposited. It is represented by coarse geodic quartz (QzII), associated with chalcopyrite that occurs in veinlets. In addition, rare galena and sphalerite are also observed. This is followed by chalcocite which exhibits tiny veins and also replacing the chalcopyrite. The silver mineralization occurs in minute veins and in the corrosion zone, replacing the preexisting sulfide minerals. Silver mineralization comprises Ag-sulfosalt, Ag-sulfide, Ag-Hg amalgam and rare native silver; iii) centimetric veins of barite and carbonate, followed by zonal quartz (QzIII) which is associated with second generation of chalcopyrite, galena and also rare sphalerite; and iv) supergene alteration stage.</div><div>The Tassafte mining area shares several common points with other Ag-Hg ore deposits in the Anti-Atlas. These points comprise comparable Ediacaran volcanic host rocks with a young Cambrian host rocks in The Tassafte area, E-W trending ore veins, and also analogous ore mineralogy. The mineralization studied here are related to post Cambrian tectonism and assumed likely associated with Variscan and Mesozoic tectonic events.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105936"},"PeriodicalIF":2.2,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577570","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 : 2025-11-17DOI: 10.1016/j.jafrearsci.2025.105935
Abdessamia El Alaoui , Nawal Bouya , Bennacer Moussaid , Said Ou Moua , Lahssen Baidder , Ahmed Fadili , Imane Haidara , Mohammed Slimani
{"title":"The role of structural legacy in the compartmentalization of the Témara aquifer, Morocco: Insight from electrical resistivity tomography and field geological data","authors":"Abdessamia El Alaoui , Nawal Bouya , Bennacer Moussaid , Said Ou Moua , Lahssen Baidder , Ahmed Fadili , Imane Haidara , Mohammed Slimani","doi":"10.1016/j.jafrearsci.2025.105935","DOIUrl":"10.1016/j.jafrearsci.2025.105935","url":null,"abstract":"","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105935"},"PeriodicalIF":2.2,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577572","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 : 2025-11-14DOI: 10.1016/j.jafrearsci.2025.105933
Nouhaila Elbakhouch , Ahmed Touil , John S. Armstrong-Altrin , Hassan Ibouh , Driss Chafiki
The paleoweathering, paleoclimate, and paleoenvironment of the clastic sediments from the Ediacaran and Cambrian Tighardine Formation in the Western High Atlas have been evaluated based on geochemical data. According to their geochemical characteristics, the sediments of Ediacaran age (Ed-S) are ranged as shale and wacke types, while those of the Cambrian age are classified as shales (Ca-S). The Chemical Index of Alteration (CIA) varies from 43.58 to 74.59 in the Ed-S (average: 58 %), and from 65.81 to 79.22 in the Ca-S (average: 75.97 %). The Compositional Maturity Index (ICV) varies from 0.81 to 1.92 in the Ed-S (average: 1.21), and from 0.66 to 1.07 in the Ca-S (average: 0.74). The Chemical Index of Weathering (CIW) varies from 49 to 98 in the Ed-S (average: 78.71), and from 79.18 to 92.71 in the Ca-S (average: 87.73). The Plagioclase Index of Alteration (PIA) varies from 31.61 to 95.29 in the Ed-S (average: 71.05), and from 75.57 to 91.21 in the Ca-S (average: 85.31). The Al2O3–CaO + Na2O–K2O and Al2O3–CaO + Na2O–FeOT + MgO ternary diagrams indicate that the Ed-S shows an immature composition and low to moderate weathering. While the Ca-S have a mature composition, high sediment recycling and moderate weathering intensity, during a predominantly semi-arid climate. Redox indicators such as V/Cr ratios, suggest that the Ed-S were deposited under anoxic condition, as evidenced by the presence of a graphitized zone within the Ediacaran Formation in the study area, while the Ca-S were formed in an oxic condition.
{"title":"Geochemical composition of the Ediacaran and Cambrian shales from the Tighardine region, Western High-Atlas, Morocco: implications for depositional environments, paleoclimate, and paleoweathering","authors":"Nouhaila Elbakhouch , Ahmed Touil , John S. Armstrong-Altrin , Hassan Ibouh , Driss Chafiki","doi":"10.1016/j.jafrearsci.2025.105933","DOIUrl":"10.1016/j.jafrearsci.2025.105933","url":null,"abstract":"<div><div>The paleoweathering, paleoclimate, and paleoenvironment of the clastic sediments from the Ediacaran and Cambrian Tighardine Formation in the Western High Atlas have been evaluated based on geochemical data. According to their geochemical characteristics, the sediments of Ediacaran age (Ed-S) are ranged as shale and wacke types, while those of the Cambrian age are classified as shales (Ca-S). The Chemical Index of Alteration (CIA) varies from 43.58 to 74.59 in the Ed-S (average: 58 %), and from 65.81 to 79.22 in the Ca-S (average: 75.97 %). The Compositional Maturity Index (ICV) varies from 0.81 to 1.92 in the Ed-S (average: 1.21), and from 0.66 to 1.07 in the Ca-S (average: 0.74). The Chemical Index of Weathering (CIW) varies from 49 to 98 in the Ed-S (average: 78.71), and from 79.18 to 92.71 in the Ca-S (average: 87.73). The Plagioclase Index of Alteration (PIA) varies from 31.61 to 95.29 in the Ed-S (average: 71.05), and from 75.57 to 91.21 in the Ca-S (average: 85.31). The Al<sub>2</sub>O<sub>3</sub>–CaO + Na<sub>2</sub>O–K<sub>2</sub>O and Al<sub>2</sub>O<sub>3</sub>–CaO + Na<sub>2</sub>O–FeO<sub>T</sub> + MgO ternary diagrams indicate that the Ed-S shows an immature composition and low to moderate weathering. While the Ca-S have a mature composition, high sediment recycling and moderate weathering intensity, during a predominantly semi-arid climate. Redox indicators such as V/Cr ratios, suggest that the Ed-S were deposited under anoxic condition, as evidenced by the presence of a graphitized zone within the Ediacaran Formation in the study area, while the Ca-S were formed in an oxic condition.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105933"},"PeriodicalIF":2.2,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577574","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 : 2025-11-13DOI: 10.1016/j.jafrearsci.2025.105931
Sakineh Arefifard , Hossein Kamyabi Shadan
This study examines stratigraphic continuity and faunal transitions across the Permian/Triassic (P/Tr) boundary within the carbonate–evaporite successions of the Dalan and Kangan formations within the Zagros Fold and Thrust Belt (ZFTB), southern Iran. By Integrating data from surface and subsurface sections — including wells from Interior, Sub-Coastal, and Offshore Fars regions (e.g., Ahmadi-1, Sefid Deng-1, Well A from South Pars) and the Kuh-e Surmeh surface section — our analysis of 1131 thin sections-reveals a tentatively continuous depositional record across the boundary. Foraminiferal assemblages, comprising 65 genera and 61 species of benthic foraminifera as well as 10 genera and 2 species of calcareous algae, align with previously published 87Sr/86Sr isotope ratios, confirming Upper Permian (Wuchiapingian-Changhsingian) strata in the Upper Dalan Member with no evidence of subaerial exposure. The extinction horizon is consistently located at the top of this member, overlain by a 2–5 m thick unfossiliferous or impoverished interval (up to ∼26.8 m in Ahmadi-1, representing a genuine feature due to diagenetic overprint under restricted basin conditions, with variations reflecting paleoenvironmental gradients). This interval is provisionally interpreted as the end-Permian mass extinction phase and is succeeded by thrombolitic and stromatolitic boundstones at the base of the Kangan Formation. Based on facies analysis and regional correlations with the Abadeh and Julfa sections, we provisionally assign the unfossiliferous interval to the Late Changhsingian. We propose the new term "Deng Member" for this distinctive boundary interval, correlating it with the Baghuk Member and boundary shale in other Iranian P-Tr reference sections. These findings refine the regional paleogeographic framework of the ZFTB during the end-Permian crisis and contribute to broader reconstructions of extinction dynamics and early Triassic environmental recovery along the southern margin of the Paleotethys.
{"title":"Lopingian and Induan deposits in the Zagros fold and thrust belt, southern Iran: Paleogeographic and stratigraphic insights into the Permian/Triassic boundary","authors":"Sakineh Arefifard , Hossein Kamyabi Shadan","doi":"10.1016/j.jafrearsci.2025.105931","DOIUrl":"10.1016/j.jafrearsci.2025.105931","url":null,"abstract":"<div><div>This study examines stratigraphic continuity and faunal transitions across the Permian/Triassic (P/Tr) boundary within the carbonate–evaporite successions of the Dalan and Kangan formations within the Zagros Fold and Thrust Belt (ZFTB), southern Iran. By Integrating data from surface and subsurface sections — including wells from Interior, Sub-Coastal, and Offshore Fars regions (e.g., Ahmadi-1, Sefid Deng-1, Well A from South Pars) and the Kuh-e Surmeh surface section — our analysis of 1131 thin sections-reveals a tentatively continuous depositional record across the boundary. Foraminiferal assemblages, comprising 65 genera and 61 species of benthic foraminifera as well as 10 genera and 2 species of calcareous algae, align with previously published <sup>87</sup>Sr/<sup>86</sup>Sr isotope ratios, confirming Upper Permian (Wuchiapingian-Changhsingian) strata in the Upper Dalan Member with no evidence of subaerial exposure. The extinction horizon is consistently located at the top of this member, overlain by a 2–5 m thick unfossiliferous or impoverished interval (up to ∼26.8 m in Ahmadi-1, representing a genuine feature due to diagenetic overprint under restricted basin conditions, with variations reflecting paleoenvironmental gradients). This interval is provisionally interpreted as the end-Permian mass extinction phase and is succeeded by thrombolitic and stromatolitic boundstones at the base of the Kangan Formation. Based on facies analysis and regional correlations with the Abadeh and Julfa sections, we provisionally assign the unfossiliferous interval to the Late Changhsingian. We propose the new term \"Deng Member\" for this distinctive boundary interval, correlating it with the Baghuk Member and boundary shale in other Iranian P-Tr reference sections. These findings refine the regional paleogeographic framework of the ZFTB during the end-Permian crisis and contribute to broader reconstructions of extinction dynamics and early Triassic environmental recovery along the southern margin of the Paleotethys.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105931"},"PeriodicalIF":2.2,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577576","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 Assarag region is located in the northern part of the Ouzellagh-Siroua salient, being a segment of the central Anti-Atlas basement bulging within the High-Atlas Belt of Morocco. It consists mainly of the Late Ediacaran Magmatic Suites (LEMS) of the Ouarzazate Group (580-539 Ma). The LEMS comprise high potassic calc-alkalic I-type granitoids that host the Imourkhssen Cu-Mo-Au-Ag porphyry mineralization. The aeromagnetic data from the Assarag region led to describe structural features in the LEMS based on their magnetic footprints. aeromagnetic datasets were processed using several transformations including the reduction to pole (RTP), Upward continuation (UC), Tilt derivative (TD), Center for Exploration Targeting (CET) and Euler deconvolution (ED) filters. RTP, TD and CET transformations allowed to map NNE-SSW, NNW-SSE and NE-SW trending faults in the north, in addition to a curved magnetic halo in the southwestern part of the Assarag area. The UC filter subdivided the Assarag area into two magnetic morpho-structural domains: a northern region with low-magnetic features, and a southern high-magnetic region with positive curved trending patterns. The ED results match and support the extracted lineaments. The aeromagnetic data were also processed by a 2D Spatio-Spectral Feature Extraction and Selection tool (SFES2D) using two-dimensional continuous wavelet transformations (2D CWT), principal component analysis (PCA) and independent component analysis by kurtosis and negentropy methods (k-ICA and n-ICA). The PCA results corroborate previously extracted lineaments and highlight a new ENE-WSW oriented structure. Meanwhile, the CWT allowed us to conclude that NNE, NNW and NE trends are shallow and emphasized deep NW-SE and ENE-WSW structures in the southern part of the Assarag area. ICA emphasizes the ENE lineament and matches the previous results. We herein define the deeper ENE trend as a part of the South Atlas Fault (SAF), which crosscuts the LEMS in the study area. Meanwhile, the shallow NE-SW and NNE-SSW tectonic features likely served as conduits for the ore-bearing fluids, leading to the Imourkhssen Cu-Mo-Au-Ag mineralization. Consequently, these directions present a valuable approach for guiding mineral exploration in the Ouzellagh-Siroua salient, from prospect to regional scales.
{"title":"Aeromagnetic data from the Assarag area (Ouzellagh-Siroua salient, Central Anti-Atlas, Morocco): Implications for the Imourkhssen porphyry mineralization","authors":"Mariam Ferraq , Saïd Belkacim , Bahman Abbassi , Li-Zhen Cheng","doi":"10.1016/j.jafrearsci.2025.105932","DOIUrl":"10.1016/j.jafrearsci.2025.105932","url":null,"abstract":"<div><div>The Assarag region is located in the northern part of the Ouzellagh-Siroua salient, being a segment of the central Anti-Atlas basement bulging within the High-Atlas Belt of Morocco. It consists mainly of the Late Ediacaran Magmatic Suites (LEMS) of the Ouarzazate Group (580-539 Ma). The LEMS comprise high potassic calc-alkalic I-type granitoids that host the Imourkhssen Cu-Mo-Au-Ag porphyry mineralization. The aeromagnetic data from the Assarag region led to describe structural features in the LEMS based on their magnetic footprints. aeromagnetic datasets were processed using several transformations including the reduction to pole (RTP), Upward continuation (UC), Tilt derivative (TD), Center for Exploration Targeting (CET) and Euler deconvolution (ED) filters. RTP, TD and CET transformations allowed to map NNE-SSW, NNW-SSE and NE-SW trending faults in the north, in addition to a curved magnetic halo in the southwestern part of the Assarag area. The UC filter subdivided the Assarag area into two magnetic morpho-structural domains: a northern region with low-magnetic features, and a southern high-magnetic region with positive curved trending patterns. The ED results match and support the extracted lineaments. The aeromagnetic data were also processed by a 2D Spatio-Spectral Feature Extraction and Selection tool (SFES2D) using two-dimensional continuous wavelet transformations (2D CWT), principal component analysis (PCA) and independent component analysis by kurtosis and negentropy methods (k-ICA and n-ICA). The PCA results corroborate previously extracted lineaments and highlight a new ENE-WSW oriented structure. Meanwhile, the CWT allowed us to conclude that NNE, NNW and NE trends are shallow and emphasized deep NW-SE and ENE-WSW structures in the southern part of the Assarag area. ICA emphasizes the ENE lineament and matches the previous results. We herein define the deeper ENE trend as a part of the South Atlas Fault (SAF), which crosscuts the LEMS in the study area<strong>.</strong> Meanwhile, the shallow NE-SW and NNE-SSW tectonic features likely served as conduits for the ore-bearing fluids, leading to the Imourkhssen Cu-Mo-Au-Ag mineralization. Consequently, these directions present a valuable approach for guiding mineral exploration in the Ouzellagh-Siroua salient, from prospect to regional scales.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105932"},"PeriodicalIF":2.2,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527432","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 : 2025-11-12DOI: 10.1016/j.jafrearsci.2025.105929
Sarah A. Mohsen , Ahmed S. Mansour , Ahmed A. El-Refaiy , Walaa S.M. Afify
This study examines the petrophysical properties of the Aheimer Formation sandstones in Northern Galala Plateau, Egypt, focusing on reservoir quality parameters including porosity (ØHe), permeability (kH), Reservoir Quality Index (RQI), Flow Zone Indicator (FZI), effective pore throat radius (R35), and Discrete Rock Type (DRT). Five distinct microfacies were identified and grouped based on porosity and permeability relationships into two main reservoir rock types (RRTs). RRT1 exhibits a strong correlation between ØHe and K (ØHe = 2.34–30.43 %, kH = 1.16–7000 mD). In contrast, RRT2 exhibits high ØHe but limited K (ØHe = 15.54–34.43 %, kH = 0.4–65 mD). Integration of microfacies, petrophysical and reservoir quality parameters identified four reservoir quality groups: Group 1 (RRT1) pebbly and porous quartz arenite – excellent reservoir quality with excellent ØHe and kH; Group 2 (RRT1) siliceous quartz arenite - good quality with fair ØHe and good kH; Group 3 (RRT1) fossiliferous dolomitic quartz arenite - tight quality with tight ØHe and poor kH; and Group 4 (RRT2) argillaceous quartz arenite - tight to poor with very good ØHe and fair kH. Cementation and/or clay matrix content primarily control the variations in reservoir quality. The novelty of this research lies in combining lithofacies, diagenetic features, and petrophysical modeling to establish predictive relationships quantitatively, thereby improving reservoir characterization of the Aheimer Formation within the Gulf of Suez Basin. The permeability, RQI, and FZI models developed (R2 ≥ 0.9) provide a reliable framework for predicting reservoir behavior and assessing hydrocarbon potential in Paleozoic sandstone systems.
{"title":"Integration of rock typing and petrophysical reservoir quality parameters for evaluating the sandstones of the Upper Palaeozoic Aheimer formation, western side of the Gulf of Suez, Egypt","authors":"Sarah A. Mohsen , Ahmed S. Mansour , Ahmed A. El-Refaiy , Walaa S.M. Afify","doi":"10.1016/j.jafrearsci.2025.105929","DOIUrl":"10.1016/j.jafrearsci.2025.105929","url":null,"abstract":"<div><div>This study examines the petrophysical properties of the Aheimer Formation sandstones in Northern Galala Plateau, Egypt, focusing on reservoir quality parameters including porosity (Ø<sub>He</sub>), permeability (k<sub>H</sub>), Reservoir Quality Index (RQI), Flow Zone Indicator (FZI), effective pore throat radius (R<sub>35</sub>), and Discrete Rock Type (DRT). Five distinct microfacies were identified and grouped based on porosity and permeability relationships into two main reservoir rock types (RRTs). RRT1 exhibits a strong correlation between Ø<sub>He</sub> and K (Ø<sub>He</sub> = 2.34–30.43 %, k<sub>H</sub> = 1.16–7000 mD). In contrast, RRT2 exhibits high Ø<sub>He</sub> but limited K (Ø<sub>He</sub> = 15.54–34.43 %, k<sub>H</sub> = 0.4–65 mD). Integration of microfacies, petrophysical and reservoir quality parameters identified four reservoir quality groups: Group 1 (RRT1) pebbly and porous quartz arenite – excellent reservoir quality with excellent Ø<sub>He</sub> and k<sub>H</sub>; Group 2 (RRT1) siliceous quartz arenite - good quality with fair Ø<sub>He</sub> and good k<sub>H</sub>; Group 3 (RRT1) fossiliferous dolomitic quartz arenite - tight quality with tight Ø<sub>He</sub> and poor k<sub>H</sub>; and Group 4 (RRT2) argillaceous quartz arenite - tight to poor with very good Ø<sub>He</sub> and fair k<sub>H</sub>. Cementation and/or clay matrix content primarily control the variations in reservoir quality. The novelty of this research lies in combining lithofacies, diagenetic features, and petrophysical modeling to establish predictive relationships quantitatively, thereby improving reservoir characterization of the Aheimer Formation within the Gulf of Suez Basin. The permeability, RQI, and FZI models developed (R<sup>2</sup> ≥ 0.9) provide a reliable framework for predicting reservoir behavior and assessing hydrocarbon potential in Paleozoic sandstone systems.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105929"},"PeriodicalIF":2.2,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527433","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 : 2025-11-11DOI: 10.1016/j.jafrearsci.2025.105930
Mohammad Abdelfattah Sarhan , El Sayed Selim
This study provides an integrated petrophysical evaluation of conventional (Matulla sandstones) and unconventional (Thebes carbonates) reservoirs in the Geisum Field, Gulf of Suez, Egypt. Wireline log data from four wells (G-9, GA-5, GA-2, and GA-1), supported by seismic interpretation, were analyzed to determine shale volume, porosity, water and hydrocarbon saturation, and net-to-gross ratios. The Matulla Formation represents a thick, laterally continuous siliciclastic reservoir characterized by effective porosity of 0.20–0.26, hydrocarbon saturation exceeding 0.70, and net-to-gross ratios up to 0.59 (GA-5). Correlation among wells reveals lateral continuity of sand bodies but with fault-controlled thickness and depth variations, indicating strong structural influence on reservoir quality. In contrast, the Thebes Formation behaves as an unconventional carbonate reservoir with moderate effective porosity (0.14–0.19), heterogeneous pay zones (25–55 ft), and net-to-gross ratios of 0.23–0.49. Correlation between GA-2 and G-9 shows marked reservoir compartmentalization governed by fracture intensity and structural position rather than depositional facies. The comparison demonstrates that while the Matulla acts as a high-quality, laterally extensive conventional reservoir, the Thebes is a fracture-enhanced, compartmentalized unconventional play. Integrating petrophysical and structural analyses therefore provides a strong framework for optimizing hydrocarbon exploration and development in fault-controlled rift basins.
{"title":"Integrated petrophysical evaluation of conventional and unconventional reservoirs: The Matulla sandstones and Thebes carbonates in the Geisum Field, Gulf of Suez, Egypt","authors":"Mohammad Abdelfattah Sarhan , El Sayed Selim","doi":"10.1016/j.jafrearsci.2025.105930","DOIUrl":"10.1016/j.jafrearsci.2025.105930","url":null,"abstract":"<div><div>This study provides an integrated petrophysical evaluation of conventional (Matulla sandstones) and unconventional (Thebes carbonates) reservoirs in the Geisum Field, Gulf of Suez, Egypt. Wireline log data from four wells (G-9, GA-5, GA-2, and GA-1), supported by seismic interpretation, were analyzed to determine shale volume, porosity, water and hydrocarbon saturation, and net-to-gross ratios. The Matulla Formation represents a thick, laterally continuous siliciclastic reservoir characterized by effective porosity of 0.20–0.26, hydrocarbon saturation exceeding 0.70, and net-to-gross ratios up to 0.59 (GA-5). Correlation among wells reveals lateral continuity of sand bodies but with fault-controlled thickness and depth variations, indicating strong structural influence on reservoir quality. In contrast, the Thebes Formation behaves as an unconventional carbonate reservoir with moderate effective porosity (0.14–0.19), heterogeneous pay zones (25–55 ft), and net-to-gross ratios of 0.23–0.49. Correlation between GA-2 and G-9 shows marked reservoir compartmentalization governed by fracture intensity and structural position rather than depositional facies. The comparison demonstrates that while the Matulla acts as a high-quality, laterally extensive conventional reservoir, the Thebes is a fracture-enhanced, compartmentalized unconventional play. Integrating petrophysical and structural analyses therefore provides a strong framework for optimizing hydrocarbon exploration and development in fault-controlled rift basins.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105930"},"PeriodicalIF":2.2,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527435","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号