Journal of African Earth Sciences最新文献

{"title":"Geospatial analysis and predictive modeling of Hofmeister ions in relation to chronic kidney disease risk in South Sinai, Egypt","authors":"Eltaher M. Shams ,&nbsp;Ahmed A. Asmoay ,&nbsp;Sahar N.E. Tawfik ,&nbsp;Rashad Sawires","doi":"10.1016/j.jafrearsci.2025.105834","DOIUrl":"10.1016/j.jafrearsci.2025.105834","url":null,"abstract":"<div><div>This study presents the first integrated geographic and predictive modeling assessment of Hofmeister ions in groundwater and their potential link to chronic kidney disease of unknown etiology (CKDu) in South Sinai, Egypt. A total of 25 groundwater samples were collected from Wadi Feiran and Wadi El Sheikh and analyzed for major ions, nutrients, and key physicochemical parameters. The results revealed alarmingly high levels of nitrate (mean = 478.1 ppm) and total dissolved solids (TDS, mean = 2093 ppm), far exceeding World Health Organization (WHO) safety standards, and pointing to substantial potential risks to public health in these arid communities. Although the weighted arithmetic Water Quality Index (WQI) classified all samples as “good” to “excellent,” detailed hydrochemical assessment showed that concentrations of Hofmeister ions—particularly calcium and sodium—surpassed safe average daily intake thresholds in many samples (21 and 16, respectively). Such exceedances raise concerns over the potential development of hypercalcemia, hypertension, and the progression of CKDu, particularly among populations with limited access to alternative drinking water sources. Hydrochemical interpretations suggest that rock–water interactions, evaporation, and anthropogenic inputs are likely contributors to the observed ion levels. Predictive modeling using multiple linear regression (MLR) demonstrated excellent performance (R² = 99.71 % for nitrate), highlighting its value in forecasting contamination trends and identifying groundwater vulnerability hotspots in data-scarce arid regions. These findings underscore the urgent need for targeted groundwater quality monitoring, the integration of predictive risk modeling into management frameworks, and the implementation of preventive public health measures. By bridging geochemical data with health risk metrics, this research provides a scientific basis for developing evidence-based policies to safeguard communities and promote the sustainable use of groundwater resources in arid environments.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105834"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145100076","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}

{"title":"Sedimentology and paleoenvironmental variations of the Late Albian/Cenomanian deposits of the Southern Tethys (Arabian Platform, Saudi Arabia)","authors":"Matthieu Deville de Periere,&nbsp;Omar Alajaji,&nbsp;Mohamed Soua","doi":"10.1016/j.jafrearsci.2025.105888","DOIUrl":"10.1016/j.jafrearsci.2025.105888","url":null,"abstract":"<div><div>The studied succession of the Wasia Formation of Saudi Arabia was deposited on the southern margin of the Shilaif Basin and comprise six members (Safaniya, Mauddud, Wara, Ahmadi, Rumaila, and Mishrif, in stratigraphic order). This study aims to refine the sedimentological understanding, depositional sequences and paleoenvironments of the Wasia Formation in the Rub’ al-Khali Basin. This study refined the identification of four 3rd order sequences, in line with the regional understanding of the Arabian Platform. The Late Albian to Early Cenomanian Safaniya Member contains orbitolinid-rich limestones and relatively deep marine deposits, the latter marking a regional flooding event associated with possibly anoxic conditions (intrashelf basin – K120MFS). This member grades upwards to shallower deposits of the Mauddud Member with rudist-rich deposits likely affected by a regional unconformity (K130SB). The clastic-rich Wara Member and the carbonates of the Ahmadi and Rumaila members (Cenomanian) are characterized by shallow marine low-energy deposits rich in diversified benthic foraminifera and green algae, with sporadic rudist developments, accounting for the K130 Sequence. Rudist deposits are inferred to have a bank geometry, with only rare <em>in-situ</em> large rudist shells. Boundaries between these members are associated with terrigenous layers at 4th order sequence boundaries. The last 3rd order sequence (K140), consisting of the Upper Cenomanian Mishrif Member, contains abundant planktonic foraminifera associated with the development of the Shilaif Basin. This integrated study unravels paleoenvironmental changes on the southern margin of the Shilaif Basin in line with the regional understanding of the Wasia Formation on the Arabian Platform, and also highlights that large rudist shoals might have been absent in the area during the Cenomanian.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105888"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324904","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}

{"title":"Identification of suitable zones and sites for rainwater harvesting to ensure urban water security in Songea, Tanzania","authors":"Mitthan Lal Kansal ,&nbsp;Suddhasil Bose ,&nbsp;Frank Tembi","doi":"10.1016/j.jafrearsci.2025.105886","DOIUrl":"10.1016/j.jafrearsci.2025.105886","url":null,"abstract":"<div><div>Urban water demand is outpacing supply due to rapid population growth and urbanization, threatening sustainability. Rainwater harvesting is a viable, low-cost solution. However, identifying suitable types of rainwater harvesting structures (RWHS) and their optimal locations remains challenging. This study focuses on mapping suitable locations and corresponding types of RWHS using a Multi-Criteria Decision-Making (MCDM) approach. The Criteria Importance Through Intercriteria Correlation (CRITIC) method has been applied to determine the importance of parameters in identifying the optimal locations and the suitability of Rainwater Harvesting Structures (RWHS). Songea is one of the fastest-growing cities in Africa, facing severe and worsening water scarcity. The study considered multiple deterministic criteria, such as annual rainfall, evapotranspiration, runoff retention capacity, elevation, slope, drainage density, population density, and proximity to settlements for the study area analysis. The significance of these criteria was aggregated using the GIS technique based on the proposed CRITIC method. Landscape metrics have been applied to assess the potential for RWH. Landscape metrics have been applied to assess the potentiality of different RWH zones. Three MCDM techniques, namely, TOPSIS, VIKOR, and EDAS are applied to rank the locations where RWHS can be efficiently implemented. The findings indicate that population density, runoff retention capacity, and annual rainfall are the most significant factors in identifying suitable locations for RWHS in the study area. Based on the RWH's suitability, Songea can be classified into five categories. Approximately 95 % of the study area is considered suitable for RWH, with 5 % classified as highly suitable. Eight locations are discretely situated within the highly suitable zone, which has been identified as priority sites for constructing check dams. Additionally, 80 locations within the 47 % suitable land are identified to construct retention basins. The top ten priority locations are situated near the core urban area and are recommended for immediate RWHS implementation. This study presents a unique and holistic framework for mapping the potential of rainwater harvesting (RWH), offering location-specific solutions for constructing RWH structures based on land suitability and priority. Implementations of proposed solutions are projected to reduce the deficit by up to 20 %, representing a significant step toward mitigating water scarcity in the region. The results provide valuable insights for administrators and urban planners, paving the way for sustainable development and efficient management of water resources.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105886"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324913","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}

{"title":"Depositional model for the Early Cretaceous estuarine, fluvio-deltaic, and braided channel deposits of the Faregh Sandstone Member, eastern Sirte Basin, Libya: Reservoir quality evaluation","authors":"Muneer Abdalla ,&nbsp;Abdalla Abdelnabi ,&nbsp;Husamaldeen Zubi ,&nbsp;Meeloud Abdullah ,&nbsp;Yousf Abushalah ,&nbsp;Saleh Qaysi","doi":"10.1016/j.jafrearsci.2025.105890","DOIUrl":"10.1016/j.jafrearsci.2025.105890","url":null,"abstract":"<div><div>The Early Cretaceous Faregh Sandstone Member constitutes major hydrocarbon reservoirs in the eastern Sirte region, Libya. Despite the member's considerable economic importance, high-resolution sedimentological and petrological studies are still limited, especially concerning their influence on reservoir formation and quality. Therefore, this study integrates core, petrographic and diagenetic analyses to examine the sedimentological features of the Faregh Sandstone Member of the Early Cretaceous Sarir Formation, with the objective of determining controls on reservoir evolution. Sedimentologic examination shows that the Faregh sandstones consist of six distinct petrofacies: quartz arenites, sublithic arenites, lithic arenites, lithic wackes, quartz wacke sandstones, and silty claystones. Core samples taken from various wells in the Faregh sandstones reveal a range of sedimentary structures. These include current ripples, both high- and low-angle tabular and trough cross-beddings, parallel laminations, and reactivation surfaces. Cores also reveal the presence of clay clasts and pebbles. Based on the petrofacies types and sedimentary structures, the various lithofacies of the Faregh sandstones are interpreted to constitute three depositional associations which represent estuarine, fluvio-deltaic, and braided river depositional settings. The estuarine facies association includes, estuarine channel and bar, bay, and tidal accumulations. The fluvio-deltaic facies association features crevasse splay, distributary channel, and mudflat to bay facies, while the braided fluvial facies association comprises braided bars, channels, and zones of channel abandonment. Diagenesis in the Faregh Member is featured by extensive quartz overgrowth cements, especially in the quartz and sublithic arenites, which often occlude intergranular pores and form interlocking textures. Moreover, kaolinite occurs in various forms, such as pore-filling, grain-replacive, and pore-lining—along with other minor clays, pyrite, hematite, partial dissolution, and rare fracture porosity. In finer-grained lithologies, such as wackes and silty claystones, diagenetic features include replacive pyrite and hematite, and moderate amounts of indeterminate clays. The reservoir quality is primarily influenced by sedimentation, with the estuarine and distributary channel and bar deposits identified as the optimal facies for the development of high-quality reservoirs. This study presents a conceptual model that supports enhanced exploration and development of the Faregh sandstones, a significant reservoir in the eastern Sirte Basin, while also offering guidance to reduce uncertainties in similar hydrocarbon systems.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105890"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145359086","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}

{"title":"Multi-stage gold mineralization in the Açdif orogenic deposit (Zenaga inlier, central Anti-Atlas, Morocco): Constraints from LA-ICP-MS analysis of pyrites and structural controls","authors":"Mohammed El Azmi ,&nbsp;Mohamed Aissa ,&nbsp;Azizi Moussaid ,&nbsp;Hafid Mezougane ,&nbsp;Said Ilmen ,&nbsp;Panagiotis Voudouris ,&nbsp;Mohmed Aissa ,&nbsp;Ilyasse Loudaoued ,&nbsp;Ait Addi Mohamed ,&nbsp;Muhammad Souiri ,&nbsp;Ilya Prokopyev ,&nbsp;El Haouiti Issmail ,&nbsp;Safouane Admou ,&nbsp;Mohamed Zouhair ,&nbsp;Lhou Maacha","doi":"10.1016/j.jafrearsci.2025.105900","DOIUrl":"10.1016/j.jafrearsci.2025.105900","url":null,"abstract":"<div><div>The Açdif gold deposit, recently discovered and exploited (∼100 koz) within the Zenaga inlier of the Moroccan Anti-Atlas, is located 30 km SW of Tazenakht. It is hosted by the Eburnean metamorphic rocks (mica schists and gneiss) of the southwestern part of the inlier. These crystalline rocks are intruded by the Tazenakht granite and the Azeguermerzi granodiorite. The assembly is intersected by a swarm of mafic dykes (gabbro and dolerite) of different directions. The gold mineralization is associated with a kilometric shear zone of WSW-ENE trending direction, which has recorded several phases of hydrothermal alterations and polyphase deformations (ductile, ductile-brittle, and brittle). Mineralized bodies are formed as quartz veins and veinlets with sulfides, or as disseminated sulfides (pyrite) in deformed metamorphic rocks. The mineral paragenesis consists mainly of pyrite, chalcopyrite, arsenopyrite, galena, scheelite, kupcikite, and Au-Ag alloy. The gangue is dominated by three distinct generations of quartz and late carbonates. Gold is refractory in pyrite, or free as grains in quartz. Electron Probe Microanalysis (EPMA) and LA-ICP-MS chemical analysis of trace elements in pyrite have distinguished two generations of pyrite: Pyrite I, forming the core of the crystals, rich in Au, Ag, Bi, Cu, and Pb, and pyrite II, forming the clear rim of the crystals, showing dominance of elements As, Co, and Ni. This chemical zoning of pyrites, notably their gold content, could inform on their origins and the gold depositional process (diagenetic origin for pyrite I and hydrothermal-metamorphic for pyrite II). The succession of deformation events and fluid circulation has resulted in two phases of gold enrichment in the deposit: The first phase, during the ductile-brittle transition, contributed to the liberation of invisible gold contained in pyrite I and its reconcentration in microfractures or as inclusions in pyrite II along with other mineral (chalcopyrite, galena, and kupcikite). The second enrichment phase is linked to the extensive brittle event, allowing the precipitation of a new generation of gold associated with the iron oxides filling the quartz veins. The Açdif gold deposit corresponds to an orogenic gold mineralization where trace elements in pyrites can be considered as indicators for the exploration of similar ore deposits at the regional scale and elsewhere.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105900"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621208","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}

{"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 ,&nbsp;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 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.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105931"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","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}

{"title":"Highly fractionated granites from Mount Al-Faráid area, South Eastern Desert, Egypt: Petrology, geochemistry and geodynamic evolution","authors":"Abdel-Aal Abdel-Karim ,&nbsp;Mokhles Azer ,&nbsp;Mabrouk Sami ,&nbsp;Azza Ragab","doi":"10.1016/j.jafrearsci.2025.105904","DOIUrl":"10.1016/j.jafrearsci.2025.105904","url":null,"abstract":"<div><div>The Mount Al-Faráid area in the southern Eastern Desert of Egypt hosts a suite of late Neoproterozoic granitic intrusions (granodiorite, monzogranite, and syenogranite) emplaced during the post-collisional stage of the Arabian–Nubian Shield (ANS). The granodiorites are distinguished by extreme LREE enrichment (ΣREE up to ∼367 ppm) and host bastnaesite-(Y) and allanite-(Ce) as primary LREE-bearing minerals, reported here for the first time in this area. All granites are strongly peraluminous (ASI &gt;1.2) and ferroan, falling in the A₂-subtype field, indicative of a post-collisional extensional tectonic setting. Geothermobarometry yields moderate crystallization temperatures (∼650–710 °C) and emplacement pressures ∼4–7 kbar (mid-crustal depths ∼19–26 km), with biotite compositions implying intermediate <em>f</em>O₂ conditions. Petrogenetically, trace element ratios (e.g., K/Rb ∼188–430; Zr/Hf &lt; 23; Nb/Ta 9–175) suggest an evolved crustal melt affected by fractional crystallization and limited assimilation. We propose that these granites were generated by partial melting of a juvenile lower-crustal source (metagreywacke to tonalitic arc crust) during lithospheric delamination and post-orogenic collapse of the ANS, followed by extensive in-situ differentiation. The presence of appreciable bastnaesite and allanite (with up to ∼33–37 wt% Y₂O₃) highlights the potential for rare-earth element (REE) mineralization, positioning these granites as a valuable exploration target for critical metals. This study provides new insights into crustal growth processes in the ANS and underscores the metallogenic significance of highly fractionated granites in post-collisional settings.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105904"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416919","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}

{"title":"Mineral chemistry of the Neoproterozoic mafic-ultramafic intrusion in the Nubian shield: Evidence of microscale element transferring during post-magmatic processes","authors":"Mohamed Zaki Khedr ,&nbsp;Shoji Arai ,&nbsp;Fatemeh Sepidbar ,&nbsp;Sherif Mansour ,&nbsp;Tehseen Zafar ,&nbsp;Zaheen Ullah ,&nbsp;Rabea A.M. Ali","doi":"10.1016/j.jafrearsci.2025.105927","DOIUrl":"10.1016/j.jafrearsci.2025.105927","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Motaghairat layered mafic-ultramafic intrusion in the Southern Eastern Desert (SED) of Egypt is relatively metamorphosed with no evidence for tectonic contacts with country rocks. This study deals with the geology, petrography, and mineral chemistry of the Motaghairat intrusion, as one of the best examples in the SED, to shed light on its emplacement thermodynamic conditions (P, T, ƒO2) and post-magmatic processes, including metasomatic history and microscale element transferring. The ultramafic rocks comprise plagioclase-bearing peridotite (dunite, lherzolite) and wehrlite with subordinate clinopyroxenite, while the mafic ones include gabbroic rocks with subordinate hornblendite and anorthosite, showing cumulate textures. The analyzed olivine grains are compositionally homogenous with narrow Fo content ranging from 85 in dunite to 81 in olivine gabbro, where their NiO content is generally low (&lt;0.3 wt%). Clinopyroxene is mainly diopside with subordinate augite (Wo&lt;sub&gt;30.76–49.21&lt;/sub&gt;En&lt;sub&gt;39.53–56.81&lt;/sub&gt;Fs&lt;sub&gt;4.52–19.60&lt;/sub&gt;) and its Mg# decreases systematically from 0.92 in ultramafic rocks to 0.69 in mafic rocks. Orthopyroxene is enstatite in composition (Wo&lt;sub&gt;0.19 – 11.47&lt;/sub&gt;En&lt;sub&gt;68.64–84.11&lt;/sub&gt;Fs&lt;sub&gt;8.26–30.1&lt;/sub&gt;) with a high Mg# (0.91) of ultramafic rocks relative to the low Mg# (0.7) of mafic ones. The mineral chemistry and back-scattered chemical mapping of coarse spinel grains reveal a marked heterogeneity with reversed chemical zoning represented by Cr-Fe-rich cores and Mg-Al-rich rims, forming Cr-spinel grains surrounded by a thin rim of Al-spinel. The occurrence of homogeneous Al-spinel (pale green) and Cr-spinel (dark brownish color) with rims of Al-spinel in ultramafic rocks suggests the formation of the former due to the interaction between spinel and melts, but the latter was formed because of a micro-scale element (Al, Mg, Cr, Fe) transfer between Cr-spinel and Al-rich silicate phases at the sub-solidus state. Some Cr-spinel grains show exsolved texture of Ti-rich ferritchromite due to subsolidus equilibration under slow cooling rates for the spinel-type solid solution. The Motaghairat mafic-ultramafic rocks fractionally crystallized from hydrous tholeiitic basaltic magma (parent melts). They are considered as a late-orogenic layered intrusion generated during the intra-arc rifting in the supra-subduction zone of the Arabian Nubian Shield. These rocks were generated in a slightly oxidizing (ΔNNO +0.03) to moderately oxidizing (ΔNNO +1.7) environment under low pressure (∼4.47 ± 0.33 kbar) and shallow depth (∼16.5 ± 1 km) conditions. Their estimated crystallization temperature shows wide ranges from ∼850 to 1200 °C (∼1000 °C on average) because of variable fractional crystallization degrees that may, in turn, result in different magmatic compositions during cooling. The occurrence of fresh dunite, wehrlite, and clinopyroxenite dykes/veins in serpentinized peridotite, along with the mineral chemist","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"234 ","pages":"Article 105927"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527483","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}

{"title":"Taphonomic signatures of the Upper Cretaceous invertebrate fauna of Wadi Qena, Eastern Desert, Egypt: biotic and abiotic controls","authors":"Omar El-Issawi ,&nbsp;Tarek Anan ,&nbsp;Heba El-Desouky ,&nbsp;Hosni Hamama ,&nbsp;Ahmed Abdelhady","doi":"10.1016/j.jafrearsci.2025.105868","DOIUrl":"10.1016/j.jafrearsci.2025.105868","url":null,"abstract":"<div><div>A detailed taphonomic analysis of fossil bivalve assemblages from the Upper Cretaceous strata of Egypt reveals significant variations in how these shells were influenced by a complex mix of biological, ecological, and environmental factors after death. Larger shells, for instance, were significantly more prone to damage, particularly fragmentation and disarticulation, than their smaller counterparts. The environment where they were deposited also played a crucial role, with shallow-water settings showing a higher degree of alteration compared to deeper marine environments, where preservation was generally better. Regardless of the rock type, disarticulation and fragmentation were consistently high, with the most intense alterations recorded in the Duwi and Dakhla formations. While evidence of bioerosion, primarily by <em>Entobia</em> <em>ovula</em>, <em>Maeandropolydora</em> isp., <em>Rogerella</em> isp., and <em>Gastrochaenolites</em> isp., and encrustation was generally low, it was slightly more common on shells found in shale. The mineral composition of different skeletal elements was also a key factor; siliceous sponges often exhibited high fragmentation but little to no bioerosion or encrustation, while calcitic shells showed a moderate degree of both disarticulation and fragmentation. The organism's lifestyle impacted its preservation; epifaunal taxa suffered the most fragmentation, whereas infaunal taxa experienced lower disarticulation but slightly increased abrasion and encrustation. Among the different groups studied, bivalves were the most heavily altered, while echinoids, brachiopods, and sponges showed only low to moderate damage. The exceptional preservation of <em>Gyrosoria gracilis</em> and <em>Porosph</em><em>ae</em><em>ra</em> <em>globularis</em> from the Sudr Chalk is likely due to the inherent durability of their brachiopod shells and spong skeletons, which made them less susceptible to destructive taphonomic processes like bioerosion and fragmentation. This underscores the significant influence of both organismal characteristics and the depositional environment in shaping the fossil record.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105868"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267515","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}

{"title":"Tomography of the source zone of the February 6, 2023, Kahramanmaraş Earthquake Doublets of Southern Anatolia","authors":"Mohamed K. Salah ,&nbsp;Hamdi Alkan ,&nbsp;Serkan Öztürk ,&nbsp;Recep Güney","doi":"10.1016/j.jafrearsci.2025.105751","DOIUrl":"10.1016/j.jafrearsci.2025.105751","url":null,"abstract":"<div><div>On February 6, 2023, two destructive earthquakes and many posterior aftershocks hit the Kahramanmaraş area in southern Anatolia. The Kahramanmaraş earthquake sequence (KMES) caused extensive damage and economic losses in Türkiye and Syria. In this study, the 3-D crustal seismic velocities surrounding the hypocentral region of the KMES are determined using a large dataset of body wave arrival times obtained from local earthquakes. To better constrain the physical properties and seismogenic behavior of the KMES source region, the Vp/Vs ratio is calculated and correlated with Poisson's ratio using the obtained velocity models. To gain a better understanding of the stress conditions and regional earthquake activity in the study area, the depth variation of the <em>b</em>-value is also examined. The velocity structure is generally heterogeneous with both low and high velocities at upper crustal depths. Along the East Anatolian Fault Zone and its environs, low-velocity anomalies are charted. Also, small <em>b</em>-values (&lt;1.0) are estimated in the region encompassing the KMES, especially at upper crustal depths. The KMES source zone is characterized by low <em>b</em>-value, low to average Vp, low Vs, and average/high Vp/Vs ratios. Hit count rates and the resolution test show that the mapped velocity anomalies are robust down to a depth of 45 km. Therefore, the moderate/high Vp/Vs and small <em>b</em>-values at the upper and middle crustal depths along the EAFZ may give constraints on the next earthquake hazards of the study region. The present findings provide deeper insight into the physical properties and the seismogenic potential of the crustal zones in proximity to the active fault segments of the Anatolian Plateau and the northwestern part of Arabia.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"233 ","pages":"Article 105751"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145100050","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}