Journal of African Earth Sciences最新文献

{"title":"A palaeoenvironmental reconstruction of the Campanian‒lower Palaeocene succession of the Dakhla Oasis (Western Desert, Egypt): Insights from integrated sequence stratigraphy, macrobenthos, and trace fossil analyses","authors":"Sara Zahran ,&nbsp;Magdy El Hedeny ,&nbsp;Ahmed El-Sabbagh ,&nbsp;Mohamed Rashwan ,&nbsp;Ahmed El-Refaiy ,&nbsp;Gebely Abu El-Kheir","doi":"10.1016/j.jafrearsci.2025.105629","DOIUrl":"10.1016/j.jafrearsci.2025.105629","url":null,"abstract":"<div><div>The palaeoenvironments of the Campanian‒lower Palaeocene composite succession in the Dakhla Oasis, Egypt, are interpreted based on the integration of sequence-stratigraphy, macrobenthic associations, and trace fossils. This succession comprises six rock units, corresponding to several transgression-regression cycles. These rock units include the Quseir Formation, the Duwi Formation, and the Mawhoob, Beris, Lower Kharga, and Upper Kharga members of the Dakhla Formation. Six unconformities delineate seven 3rd-order depositional sequences, including the lower‒middle Campanian DS-Q1, the upper Campanian DS-D1 and DS-D2, the lower Maastrichtian DS-Dk1, the upper Maastrichtian DS-Dk2 and DS-Dk3, and the lower Danian DS-Dk4. The invertebrate macrobenthic elements sporadically occurred throughout the studied succession, representing three bivalve associations: the late Campanian <em>Nicaisolopha</em>-<em>Plicatula</em> association, the late Maastrichtian <em>Exogyra overwegi</em> association, and an early Danian <em>Venericardia</em> association. At least 12 ichnotaxa have been identified, representing two ichnoassemblages: the late Campanian <em>Thalassinoides</em>-<em>Psilonichnus</em> and the latest Maastrichtian‒early Danian <em>Rhizocorallium jenense</em>-<em>Tisoa siphonalis</em>, both belonging to the <em>Glossifungites</em> Ichnofacies. Sequences characteristics indicate palaeoenvironments ranging from brackish, littoral, and near-shore to inner and outer neritic settings, reflecting the influence of syn-sedimentary tectonics combined with sea-level fluctuations, which resulted in varied depositional features. The distribution and the trophic structure of the body and trace fossil assemblages confirm the role of several environmental parameters, such as substrate characteristics, bathymetry, water energy, productivity level, sedimentation rates, and oxygen availability, in shaping the occurrence of different elements within these faunal assemblages.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105629"},"PeriodicalIF":2.2,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143642950","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":"Eocene subvolcanics with slab failure magmatism affinity in the Samakhon area, NE Iran: Evidence of Pre-Lutecian collision of the Central Iran and the Eurasian Plates","authors":"Bahareh Borouzi Niyat ,&nbsp;Azadeh Malekzadeh Shafaroudi ,&nbsp;Hossein Azizi ,&nbsp;Mohammad Hassan Karimpour ,&nbsp;Yoshihiro Asahara ,&nbsp;Behnam Rahimi","doi":"10.1016/j.jafrearsci.2025.105624","DOIUrl":"10.1016/j.jafrearsci.2025.105624","url":null,"abstract":"<div><div>Porphyritic monzogranite and diorite considered as subvolcanic bodies are exposed in northeastern Iran as stocks and dikes in the Samakhon region. Zircon U–Pb dating yields ages ranging from 48.2 to 42.9 Ma for these rocks. Whole rock chemistry shows large variation of SiO₂ (54.6–65.4 wt %), MgO (0.19–5.49 wt %), and the alkaline elements contents (Na₂O + K₂O = 5.54 to 7.53 wt %), and display a positive Eu anomaly (Eu/Eu∗ = 0.95–1.2). High contents of the large ion lithophile elements (e.g., Sr, Rb, Cs, and Ba), high LREE/HREE ratios (La_N/Yb_N = 0.9–1.4), and negative Ta, Nb, and Ti anomalies are consistent with the calc-alkaline magmatic series emplaced along active margins. The initial ⁸⁷Sr/⁸⁶Sr ratios and εNd_i values change from 0.7052 to 0.7063, and from −3.0 to −0.4, respectively suggesting the involvement of crustal components in the sources of these rocks. Nb/Y (1.5), Gd/Yb (2.9), La/Yb (24.8), Sm/Yb ratios (3.3), and Nb abundances (15.1–19.9) are high compared to typical arc magmatism, suggesting that these rocks are likely associated with slab failure. The metasomatic mantle above the subduction zone in a pre-to post-collisional regime is the most likely candidate for the sources of these rocks. The development of the Sabzevar Cretaceous arc-related magmatism and the situation of the Samakhon subvolcanic rocks with younger age (48-42 Ma) in the northern Sabzevar suture zone, can be attributed to slab failure magmatic activity after the collision between the Central Iran Block and the Eurasian plate during the Early Eocene. The current model suggests that the closure of the Sabzevar ocean and the collision in northeastern Iran happened earlier than formerly assumed, which was previously thought to have occurred in the Late Eocene.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105624"},"PeriodicalIF":2.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643463","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":"Assessment of synthetic zeolites from kaolin and bentonite clays for wastewater and fuel gases treatment","authors":"Ahmed Abdelhalim ,&nbsp;Ahmed Melegy ,&nbsp;Dina Othman","doi":"10.1016/j.jafrearsci.2025.105621","DOIUrl":"10.1016/j.jafrearsci.2025.105621","url":null,"abstract":"<div><div>The present study evaluates the synthesis, geochemical and mineralogical characterization, as well as the industrial and environmental applications of zeolites synthesized from kaolin and bentonite resources in selected clay deposits of Northeast Africa, Egypt. Several methods were employed to synthesize zeolites from both kaolin and bentonite samples to obtain high purity zeolitic products at a competitive cost. The characterization of the synthesized zeolites, in terms of mineralogy and geochemistry, was conducted using various techniques, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and cation exchange capacity (CEC). Additionally, thermo-analytical methods such as thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used. Based on the characterization of zeolites synthesized from bentonite and kaolin, a comparison was made with ideal zeolites used in various industries to determine their potential applications. The synthesized zeolites were evaluated for their effectiveness as adsorbents for H₂S in wastewater and fuel gas purification. Additionally, they were assessed for their ability to remove ions such as Co²⁺, Sr²⁺, and Cs⁺ from aqueous solutions containing organic and suspended solids. Furthermore, these zeolites were investigated for their potential use as commercial and sustainable catalysts for controlling nitrogen oxide (NOx) emissions from diesel engines in vehicles.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105621"},"PeriodicalIF":2.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637474","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":"Exploring the Gebel Kamil impactoclastic fallback deposits in Egypt: Their origin and post-impact alteration using SEM/AM and Cathodoluminescence techniques","authors":"Nahla A. Shallaly ,&nbsp;Mona Kabesh ,&nbsp;Sabine Gilbricht ,&nbsp;Ahmed N. El Barkooky ,&nbsp;Mohamed El Sharkawi ,&nbsp;Jens Götze ,&nbsp;Bernhard Schulz","doi":"10.1016/j.jafrearsci.2025.105618","DOIUrl":"10.1016/j.jafrearsci.2025.105618","url":null,"abstract":"<div><div>A Scanning Electron Microscope (SEM)-based Automated Mineralogy (SEM-AM) analysis and Cathodoluminescence (CL) were used to study the mineralogy and texture of a vertical 60 cm profile within the Gebel Kamil impactoclastic fallback deposits. The SEM/AM technique was employed to quantify mineralogical and textural criteria such as distribution, grain size, sorting, mineral association, and shape of clastic deposits in two units of the profile. Microscopically, these deposits are composed mainly of unshocked and shocked quartz, along with impactogenic particles such as lithic ejecta, glassy and impact melt fragments, and projectile shrapnel. SEM/AM effectively identified taenite as the main projectile debris, distinguished various primary mineral phases and related alterations, and microscopically unresolvable inclusions such as tantalite. The impact melt composition was characterized as a Si-rich lechatelierite white melt surrounded by a dark melt. The SEM/AM analysis delineated the composition variance between (Fe-rich) hematite and (Fe-Al-Si-rich) almandine melts. Quantitative textural aspects of the SEM/AM indicate a higher concentration of shocked and other impactogenic particles in the lower unit of the deposits created by the impact plume, whereas the more sorted, finer, more altered upper unit inferred a higher degree of mixing with non-impact related Holocene sediments. The CL results identified shock-induced features, alteration products, and zoning in specific minerals. They also provided insight into the origin of the target rocks, indicating their derivation from a Precambrian complex. The vertical variation of authigenic minerals suggests the presence of a phyllic, post-impact hydrothermal alteration affecting these porous deposits.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105618"},"PeriodicalIF":2.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629228","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":"Phase relations in Co-Ni-Fe-(±Au ±Ag) mineralizations of Bou Azzer-El Graara inlier, central Anti-Atlas, Morocco: Insights from mineral chemistry and fluid inclusions analysis","authors":"Muhammad Souiri ,&nbsp;Mohamed Aissa ,&nbsp;Abdelaziz El Basbas ,&nbsp;Ahmed H. Ahmed ,&nbsp;Ilyasse Loudaoued ,&nbsp;Hafid Mezougane ,&nbsp;Mohammed El Azmi ,&nbsp;Azizi Moussaid ,&nbsp;Hassane Ouguir ,&nbsp;Mohamed Ait Addi","doi":"10.1016/j.jafrearsci.2025.105606","DOIUrl":"10.1016/j.jafrearsci.2025.105606","url":null,"abstract":"<div><div>The Bou Azzer East deposit is located in the western part of the Bou Azzer inlier, where many orebodies of Co-Ni-Fe ± Au ± Ag are actively mining. These orebodies are mainly controlled by late Pan-African and/or Hercynian structures. The Co–Ni arsenide-sulfarsenide mineralization at Bou Azzer East is associated with serpentinite rocks, and possesses two modes of occurrence: (i) at the contact between serpentinite and quartz diorite or Ediacaran volcanic rocks, with veins sometimes extending into serpentinite; (ii) as orebodies crosscutting quartz diorite (vein-type). The Bou Azzer Co-Ni mineralization proposed to be formed by three stages: (1) pre-mineralization stage, characterised by the presence of chromite and talc; (2) arsenide mineralization stage (mono-, di-, tri-arsenides and sulfarsenides) associated with quartz gangue; and (3) sulphide mineralization stage accompanied by carbonate gangue. These stages of mineralization are temporally arranged and separated by brittle deformation episodes. Except for the first stage, inclusions of native-Au and electrum (Au-Ag) are found in the subsequent stages of arsenides, sulfarsenides, and sulphides. Native-Au is also emphasized in the supergene stage. Micrometric analysis of fluid inclusions (FI) was carried out on quartz and calcite gangues. FI trapped in quartz show that arsenides and Au-Ag mineralization precipitated from hydrothermal fluids at temperatures ranging from 200 to 350 °C and salinities ranging from 15 to 45wt% NaCl equiv. The sulphide and Au-Ag assemblage, hosted in calcite gangue, is most probably formed from fluids with temperature ranging from 200 to 250 °C and salinities between 25 and 45 wt% NaCl equiv. The precipitation of the ore minerals is related to fluid mixing, boiling, and cooling at different temperatures and salinities. Weathering of hypogene arsenides and sulphides minerals led to the formation of heterogeneous secondary minerals, including erythrite, roselite, chalcocite, bornite, and native gold. This phenomenon, driven by leaching and fluid-rock interactions, contributed to the formation of these secondary minerals.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105606"},"PeriodicalIF":2.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143642949","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":"Comparison of ground and aero magnetic data in the Eastern Pontides (Türkiye) and inferences regarding the crustal structure with the support of gravity data","authors":"Murat Özkaptan ,&nbsp;Tuğçe Özkaptan ,&nbsp;Ali Erden Babacan","doi":"10.1016/j.jafrearsci.2025.105620","DOIUrl":"10.1016/j.jafrearsci.2025.105620","url":null,"abstract":"<div><div>Magnetic and gravity surveys are widely utilized in geological research due to their efficiency and rapid data acquisition capabilities. Various global data platforms integrate measurements obtained from ground, sea, and airborne surveys. However, combining these datasets can sometimes lead to a reduction in resolution.</div><div>This study aims to analyze both airborne and ground magnetic data in the Eastern Pontides to assess this issue. A comparison of the two data sources, following normalization, reveals significant similarities. Magnetic anomaly values obtained from both different data sources overlap by almost 90 %. Additionally, the findings suggest that conducting ground magnetic surveys at intervals of no more than 10 km is sufficient for modeling large-scale deep structures.</div><div>The second objective of this study is to integrate magnetic data with Bouguer gravity data to develop a conceptual crustal model for the Eastern Pontides. Contrary to the commonly suggested monotonous increase in crustal thickness from north to south, this study identifies a gravity anomaly of approximately 50 mGal in the southern part of the region, indicating a localized thinning of the crust. Furthermore, the results demonstrate that combining ground and aeromagnetic data provides a more detailed and reliable assessment of crustal thickness variations.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105620"},"PeriodicalIF":2.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619266","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":"Geochemistry and provenance of Birimian metasedimentary rocks of Téra area, Leo-Man Shield, West Niger","authors":"Hamidou Garba Saley ,&nbsp;Moussa Konate ,&nbsp;Olugbenga Akindeji Okunlola","doi":"10.1016/j.jafrearsci.2025.105609","DOIUrl":"10.1016/j.jafrearsci.2025.105609","url":null,"abstract":"<div><div>This study presents the provenance of metasedimentary rocks (including amphibolites, mica schists, quartzites, and gondites) of the Téra area, using petrographic and geochemical (whole rock) analyses.</div><div>The methodology employed in this study involves a field investigation (sampling and mapping) followed by a petrographic analysis using a transmitted light polarized microscope and finally, a geochemical analysis through ICP-MS method. The major oxides (SiO₂/Al₂O₃ vs K₂O/Na₂O diagram) and trace elements (La-Th diagram) show that all the samples come from Archean sediments, except for three amphibolite samples which are highly enriched in La and Th due to contamination. The geochemical classification plot [log (Na₂O/K₂O) vs log (SiO₂/Al₂O₃)] shows a shale-sand-ferruginous composition of sediments. Calculation of the Index of Compositional Variability (ICV) indicates that the amphibolites and gondites sediments characterized by high ICV values are derived from immature sediments, reflecting a proximal source rock and rapid deposition. on the other hand, the mica schist samples, with low ICV values, be mature sediments derived from a distal source rock. The quartzite samples are a mixture. The Al₂O₃/TiO₂ ratios, the TiO₂ vs. Zr plot and the La/Th vs. Hf diagram suggest a mafic, intermediate to felsic igneous parent source origin with an intermediate source predominant from active tectonic setting (magmatic arc). The LILE group (Sr, Ba, Rb, K) and incompatible elements (Ce, La, Nb, Th) concentrations of mica schists, amphibolites, and quartzites samples are close to those of crust continental, except for gondites and two quartzite samples (A1 and A3) which are close to Morb, and show LILE depletion. The evaluation of the alteration degree shows that all amphibolites and quartzites (except one) samples have the lowest degrees of alteration. While the mica schists and the fresh gondite samples (at the bottom of hills) have a moderate degree of alteration. The gondite samples located towards the top of hills have extreme degrees of alteration. These high alterations suggest a chemical weathering in warm and humid climatic conditions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105609"},"PeriodicalIF":2.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637476","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":"Two interconnected stages in the formation of the Tamazeght magmatic complex (Moroccan central High Atlas) determined by apatite, zircon and titanite U-Pb geochronology","authors":"Jamal Achmani ,&nbsp;Thomas Blaise ,&nbsp;Ilham Chraibi ,&nbsp;Jocelyn Barbarand ,&nbsp;Nathan Cogné","doi":"10.1016/j.jafrearsci.2025.105623","DOIUrl":"10.1016/j.jafrearsci.2025.105623","url":null,"abstract":"<div><div>The intraplate magmatic complex of Tamazeght (or Tamazert), located in the central High Atlas of Morocco, formed during the Eocene in response to N-S oriented compressive shear movements associated with the convergence between Africa and Europe. The ages of emplacement of certain rocks forming this complex have been determined so far using K-Ar radiometric dating on biotite (from carbonatites and monzonites) and K-feldspar (from nephelinite dykes), as well as Rb-Sr geochronology on whole rock (nepheline monzodiorite). Furthermore, U-Pb geochronology has so far only been applied to eudialytes in the syenites and zircon in the monzonite and late-stage vein. However, uncertainties remain regarding the timing of emplacement of basic cumulates, syenites and lamprophyre dykes. In addition, the ages reported in the literature do not allow discussion of the continuous or multistage formation of the Tamazeght complex. In this paper, we use U-Pb geochronology on zircon, apatite and titanite crystals to clarify the sequence of events that formed the Tamazeght complex. Considering previously published and our new data, two interconnected magmatic stages have been identified. The first stage (ca. 47-44 Ma) corresponds to the plutonic rocks of the jacupirangite-ijolite ultrabasic cumulate sequence, whose age was previously undocumented. The second stage (ca. 44-35 Ma) includes more differentiated plutonic units (ca. 44-41 Ma), as defined by two U-Pb ages obtained from syenite zircons that agree with previous ages. A lamprophyre dyke located south of the complex gave a U-Pb age of 42.2 ± 1.9 Ma on titanite and can be attributed to the vein phase (ca. 43-35 Ma) of this second magmatic stage. This phase involves the intrusion and/or extrusion of several carbonatite, lamprophyre, and phonolite dykes. The Tamazeght magmatic activity is characterized by its short duration, from the early Lutetian to the early Priabonian (ca. 10 My), in relation to the regional geodynamic processes of the first Atlasic phase during the Alpine orogeny.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105623"},"PeriodicalIF":2.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643464","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":"Soil erosion and sediment yield in Africa: Processes and factors","authors":"Abdelali Gourfi ,&nbsp;Matthias Vanmaercke ,&nbsp;Jean Poesen ,&nbsp;Joris de Vente ,&nbsp;Mourad Aqnouy ,&nbsp;Aude Nuscia Taibi ,&nbsp;Roberto Valentino ,&nbsp;Lahcen Daoudi ,&nbsp;Sofie De Geeter ,&nbsp;Hamza Briak","doi":"10.1016/j.jafrearsci.2025.105622","DOIUrl":"10.1016/j.jafrearsci.2025.105622","url":null,"abstract":"<div><div>Africa experiences diverse and often intense soil erosion processes, yet the interplay between these processes and observed sediment yield (SY) at catchment scales is insufficiently understood. Building on previous continental-scale assessments, this study integrates a newly verified database of measured SY at 425 river outlets with, model-based estimates of Rill and Sheet Erosion (RSE), Landslide Mobilization Rates (LMR), and Gully Head Susceptibility (GHS). Our approach addresses a key gap in earlier work, which primarily relied on environmental predictors without explicitly quantifying the contribution of multiple geomorphic processes.</div><div>Our results indicate that the mean observed SY is 6.07 t⋅ha⁻¹⋅yr⁻¹, whereas modelled RSE and LMR average 9.42 t⋅ha⁻¹⋅yr⁻¹ and 1.51 t⋅ha⁻¹⋅yr⁻¹, respectively. Although direct estimates of gully erosion were not available, the moderate to strong correlations between SY and both LMR (r = 0.47) and GHS (r = 0.57) underscore the importance of gullies and landslides in delivering sediment to catchment outlets. In contrast, RSE shows a weaker relationship with measured SY, suggesting that traditional RUSLE-type models may substantially over- or underestimate total sediment yield if they neglect gully erosion, landslides, and in-channel deposition processes.</div><div>This study contributes novel insights into continental-scale sediment dynamics by explicitly linking observed SY to distinct geomorphic processes. Our findings highlight the need for integrated modeling frameworks that account for rill and sheet erosion, landslides, and gully erosion in order to enhance the accuracy of sediment yield predictions. Such approaches are vital for guiding land management and soil conservation strategies across Africa's diverse biophysical and climatic regions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105622"},"PeriodicalIF":2.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629227","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":"Facies analysis of Late Pleistocene mixed carbonate-siliciclastic transgressive-regressive sequence along the coast near Mogadishu (Somalia)","authors":"Federico Carbone ,&nbsp;Ruggero Matteucci ,&nbsp;Giovanni Accordi ,&nbsp;Mario Voltaggio","doi":"10.1016/j.jafrearsci.2025.105607","DOIUrl":"10.1016/j.jafrearsci.2025.105607","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The raised sedimentary complex outcropping along the coastal belt just south of the Mogadishu airport is a roughly 10-m-thick carbonate–siliciclastic, coral-bearing depositional sequence. This complex is defined by eight primary depositional facies that form a transgressive–regressive sedimentary cycle, capped by a regressive surface that gently dips seaward.&lt;/div&gt;&lt;div&gt;Facies analysis reveals a transgressive system tract consisting of a stratal set of siliciclastic sand deposited above a wave-ravinement surface, as indicated by an eroded quartz sand substratum. The transgressive succession continues with loose siliciclastic sand that contains a rich mollusk fauna intermixed with coarse skeletal debris of stony corals and both encrusted and articulated coralline algae. The macrofossil assemblage indicates diverse shoreface environments, where water depth, bottom morphology, and distance from the shoreline are critical in characterizing each facies.&lt;/div&gt;&lt;div&gt;Comparisons with the modern biological zonation of the shallow shelf along the southern Somali coast have helped clarify the depositional characteristics of the Pleistocene facies succession. The distribution of fossil coral communities—often with colonies still in growth position—suggests a series of shallow-water facies related to back reef–shore environments that migrated landward over time. In contrast, the highstand system tract differs from the underlying facies by exhibiting a drastic decrease in the siliciclastic granular fraction and corals in growth position, which is offset by an increase in articulated and encrusted coralline algae that comprise most of the sediment source. Locally, skeletal rubble rich in large coralline algal nodules is typical of the regressive phase. The deposition of these facies results in a smoothing of seafloor roughness due to the burial of coral buildups by skeletal sand that shows less facies diversification.&lt;/div&gt;&lt;div&gt;The marine succession—affected in its upper part by the calichification process—culminates in a marine terrace capped by aeolian sands deposited during various depositional–erosional events. Some of these deposits correlate with raised beachrock that outcrops discontinuously just above present sea level and corresponds to a minor Holocene sea level highstand.&lt;/div&gt;&lt;div&gt;To assess the time interval required for the deposition of this transgressive–regressive cycle, which is related to a Late Pleistocene sea level positive peak, sedimentation rates and U–Th dating of two samples of massive &lt;em&gt;Porites lutea&lt;/em&gt; from the transgressive system tract have been considered. The ages of approximately 114 kyr indicate a flooding event on the southern Somali coast during the transition between stages 5e and 5d of the Last Interglacial, while the overall duration of the sedimentary cycle is likely much less than 10 kyr. Furthermore, by matching the investigated cycle with positive peaks on significant global and local sea level curves, addit","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105607"},"PeriodicalIF":2.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619375","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}