Journal of African Earth Sciences最新文献

{"title":"Caldera-style migratory volcanism at Gabel Tarbtie, Southern Egyptian Nubian Shield: Petrological, geochemical, and structural insights","authors":"Abdelhady Radwan ,&nbsp;Ashraf Emam ,&nbsp;Hassan Khozyem ,&nbsp;Gehan B. El Shaib ,&nbsp;Mohammed H. Younis","doi":"10.1016/j.jafrearsci.2025.105793","DOIUrl":"10.1016/j.jafrearsci.2025.105793","url":null,"abstract":"<div><div>The Gabel Tarbtie ring complex represents important caldera style magmatism in the Egyptian Nubian Shield. The massive association formed from a migratory magmatic midst ex-position as circular entities in three adjacent sectors with analogous lithological and structural features: two sectors forming the Tarbtie South (TS) and the other forms the Tarbtie North (TN). The rocks forming the two rings occur as a wide spectrum of petrographic sets including nepheline syenite, biotite-amphibole – aegirine bearing syenite, carbonitized syenite, nordmarkite, syenogranite, carbonatite and pyroclastics. The whole association is injected by andesitic to basaltic dykes, and affected by fenitization processes. Geochemically, the Gabel Tarbtie rocks belong to anorogenic intraplate A₁-type alkaline complexes. They have high amounts of alkalis and show enrichment in some HFS elements (i.e. Ba, Nb, Zr, Y), mainly having meta-aluminous ferrouan nature. It is believed that during the post-orogenic times tension and uplift could cause migration of the decompression portion, and advance partial melting which promotes magma generation. The Gabel Tarbtie association was developed as result of migratory magmatic pulses evolved over a 15 km along NW lineaments or deep-seated fractures. Subsequently, the mature caldera outline was influenced by NE structural trend.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105793"},"PeriodicalIF":2.2,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738104","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":"The Shadli metavolcanic belt in the south Eastern Desert of Egypt: A late Tonian-Cryogenian hotspot track in the northern Arabian-Nubian Shield","authors":"Robert J. Stern ,&nbsp;Mohamed Zaki Khedr ,&nbsp;Martin Whitehouse ,&nbsp;Madhusoodan Satish Kumar ,&nbsp;Yuruo Shi ,&nbsp;Mahmoud A. Sayed","doi":"10.1016/j.jafrearsci.2025.105795","DOIUrl":"10.1016/j.jafrearsci.2025.105795","url":null,"abstract":"<div><div>The Shadli Metavolcanic Belt (SMB) trends ∼120 km E-W and 20–40 km wide in SE Egypt; its origin (rift, plume, arc) and age (∼695–750 Ma) are controversial. Intermediate and felsic samples from two areas in the eastern belt were studied for U-Pb zircon ages and oxygen isotopes by ion probe and Hf isotopes by LA-ICP-MS and for whole rock Sr and Nd isotopic compositions. Three (Late Tonian) concordia ages of 738.4 ± 3.4, 739.2 ± 3.7 and 727.2 ± 6.5 Ma were determined. Oxygen isotopes range ∼4.4–4.6 ‰, significantly lower than the nominal mantle zircon average of 5.3 ‰, indicating the involvement of a hydrothermally altered crust. Hf isotopic compositions yield ε_Hf(t) with a mean of +13.8; whole-rock initial ⁸⁷Sr/⁸⁶Sr isotopic compositions average 0.7027 and εNd (739 Ma) averages +5.1; these indicate a depleted mantle source with no participation of old continental crust. Integrating our new results with those of other studies reveals a westward decrease in age for the eastern SMB at ∼1 km/Ma. This is unexpected for a volcanic arc and is best explained by eastward motion of the Arabian-Nubian Shield over a fixed mantle hotspot. Trace element compositions suggest both OIB-like and arc-like mantle sources for basalts and arc-like sources for differentiated lavas. These observations are best explained by entrainment of older subduction-modified lithospheric mantle in a rising mantle plume followed by partial melting of a mixed mantle source at the top of the base of the crust to generate basalts and interaction of mafic magmas with &gt;750 Ma juvenile arc to generate fractionated lavas with arc-like trace element characteristics. The results of this study should motivate research to determine ages and isotopic compositions of the western half of the SMB, study relationship of SMB to the batholith flanking it on the north, study a N-S transect across the SMB and revise SMB mineral exploration strategies.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105795"},"PeriodicalIF":2.2,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738103","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":"Clinopyroxene geochemistry and zoning as a petrogenetic tool to assess the crystallization conditions of the alkaline Talzast Dome (Middle Atlas, Morocco)","authors":"B. Mali ,&nbsp;M. Dahire ,&nbsp;A. Ntarmouchant ,&nbsp;Y. Driouch ,&nbsp;T. Bento dos Santos ,&nbsp;N. Har ,&nbsp;M. Elabouyi ,&nbsp;E.M. Jeddi ,&nbsp;H. Smaili ,&nbsp;S. Zerouali ,&nbsp;N. Ntarmouchant ,&nbsp;T. Catita ,&nbsp;B. Cotrim ,&nbsp;A.R. Rosa ,&nbsp;F. Laguenini ,&nbsp;M. Belkasmi","doi":"10.1016/j.jafrearsci.2025.105785","DOIUrl":"10.1016/j.jafrearsci.2025.105785","url":null,"abstract":"<div><div>Located in the SW border of the Middle Atlas Causse, the Talzast Dome comprises highly SiO₂-undersaturated nephelinites with singular features. This Miocene volcanic dome displays a zoned structure whose rock types change from the periphery towards the centre regarding texture and mineralogical composition. The external zone of the dome is made of ankaratrite (a melanocratic variety of olivine nephelinite displaying a porphyritic microlitic texture), the intermediate zone is composed of fasinite (feldspar-free medium-grained variety of melteigite), and the central zone consists of coarse-grained to pegmatitic ijolite named talzastites in honour of the Talzast area. Such coarse-grained and pegmatitic ijolite were previously unknown in the entire Middle Atlas Miocene-Quaternary magmatic province.</div><div>The Talzast Dome nephelinites contain abundant clinopyroxene phenocrysts and microcrysts, with complex zoning patterns. Three distinct types of clinopyroxene were identified based on their zoning patterns: a) type 1 exhibits reverse zonation with low-Mg# rounded resorbed cores (Mg# = 66–79), surrounded by high-Mg clear rims (Mg# = 72–84); b) type 2 phenocrysts generally display normal zonation, with high-Mg cores (Mg# = 75–85) and low Mg rims (Mg# = 53–75); c) type 3 phenocrysts are euhedral and show no zonation pattern. The textural and compositional features of the studied clinopyroxenes suggest the presence of antecrysts and autocrysts, reflecting complex magmatic processes.</div><div>Thermobarometric Clinopyroxene-liquid and Clinopyroxene-only calculations for the studied rocks revealed a wide P-T range, varying from 0.04 to 14.73 kbar (±1.5 kbar) and 1008 to 1233 °C (±52–60 °C), respectively. Furthermore, the data indicates the existence of three main magma storage zones at depth: a) a deep magma reservoir (≃ 27 km); b) an intermediate magma reservoir (≃10 km); and c) a shallow magma reservoir (≃ 2 km). Whole-rock geochemistry suggests that the Talzast Dome rocks resulted from magmatic differentiation processes that occurred in a shallow magmatic reservoir, as indicated by the detailed mineral-scale analysis of the clinopyroxene crystals. Ankaratrite represent the least differentiated rock, followed by fasinites. Talzastites are the most differentiated products of this dome. The genesis of pegmatitic rock-types imply the influence of volatile agents, concentrated after the bulk of fractional crystallization had occurred.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105785"},"PeriodicalIF":2.2,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738106","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-disciplinary approach to reservoir characterization and 3D static modeling of the Paleozoic to Middle Jurassic Sequence in the Obaiyed Field, Shushan Basin, Egypt","authors":"Hoda A. Diab ,&nbsp;Ahmed S. Mansour ,&nbsp;Bassem S. Nabawy ,&nbsp;Walaa S.M. Afify ,&nbsp;Munir Elmahdy ,&nbsp;Ahmed Diab","doi":"10.1016/j.jafrearsci.2025.105788","DOIUrl":"10.1016/j.jafrearsci.2025.105788","url":null,"abstract":"<div><div>The Obaiyed Field, located in Egypt's Shushan Basin, is a geologically complex tight gas reservoir. Despite its substantial gas reserves, production remains restricted, leading to the suspension of several wells. This study integrates geological and petrophysical datasets, including core descriptions, imaging logs, conventional well logs, and seismic data, to develop detailed structural, facies, petrophysical, and hydraulic flow models. In the uncored zones, permeability was estimated using artificial neural networks calibrated with core data. Structural modeling identified a network of NW–SE and NNE–SSW trending normal faults, adding to the field's structural complexity. The Lower Safa Member shows better reservoir potential and comprises approximately 93.8 % sandstone deposited in a deltaic environment with tidal and fluvial influence. In contrast, the Shifah Formation contains only 22.45 % sandstone, with a higher proportion of shale and siltstone, indicating deposition in a deeper marine environment. Petrophysical analysis of the Lower Safa Member indicates that its reservoir quality decreases toward the north. The study of Hydraulic Flow Units (HFUs) identified five distinct units, with HFU5 (predominant in the Lower Safa Member) having the best reservoir quality, while HFUs 2–3 (common in the Shifah Formation) have much lower flow potential. These findings offer crucial guidance for the exploration and development of tight clastic reservoirs in the Northwestern Desert basins of Egypt and may also be relevant to similar analogues in North Africa.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105788"},"PeriodicalIF":2.2,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771449","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":"First report of late Messinian Lago-Mare micropaleontological assemblage in northeastern Algeria (Beni Fouda Basin)","authors":"Sidali Chine ,&nbsp;Rim Temani ,&nbsp;Fateh Mebrouk ,&nbsp;Hayet Khayati Ammar ,&nbsp;Mehiddine Amimour ,&nbsp;Francesco Sciuto","doi":"10.1016/j.jafrearsci.2025.105783","DOIUrl":"10.1016/j.jafrearsci.2025.105783","url":null,"abstract":"<div><div>This study presents the first detailed micropaleontological investigation of Late Messinian Lago-Mare facies in the Beni Fouda Basin (Northeastern Algeria). Analyzing 20 samples from four stratigraphic sections (KAL, KAU, KAM, DH), our findings reveal an oligotypic micropaleontological assemblage comprising six ostracod taxa (five genera) alongside dominant charophytes, with <em>Sphaerochara miocenica</em> being the only species formally identified. The assemblage, characterized by euryhaline <em>Cyprideis</em> species and freshwater taxa like <em>Ilyocypris gibba</em> and <em>Candona angulata</em>, indicates transitional lagoonal environments with significant fluvial influence. Here, we report the first documented occurrence of the genus <em>Zonocypris</em> in North Africa, contributing new data to our understanding of its biogeographic distribution.</div><div>A major contribution of this study is the stratigraphic positioning of Lago-Mare deposits above the Turolian Amama 2 vertebrate level, which significantly reduces the estimated hiatus between the Turolian and Pliocene in northeastern Algeria. This finding refines the regional stratigraphic framework and highlights regional variations in Lago-Mare environments. Unlike the Chelif Basin, the Beni Fouda Basin is characterized by a persistent freshwater influence, the absence of marine planktonic microfossils, and a lack of evidence for the Messinian Erosional Surface, emphasizing the influence of local factors on Messinian paleoenvironments. Furthermore, the presence of Paratethyan-affinity taxa supports the hypothesis that the paleo-Sicily Channel allowed faunal exchange between the Eastern and Western Mediterranean during the Late Messinian. This first report of Lago-Mare species in northeastern Algeria provides significant new insights into the stratigraphy and the Messinian-Pliocene transition in the region.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105783"},"PeriodicalIF":2.2,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704059","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":"Climate and Nile floods in ancient Egypt: Insights from the isotope composition of freshwater shells and geochemistry of Saqqara-Memphis floodplain, Egypt","authors":"Mohamed A. Hamdan ,&nbsp;Fekri A. Hassan ,&nbsp;Roger J. Flower ,&nbsp;Hanan S. Badawy","doi":"10.1016/j.jafrearsci.2025.105789","DOIUrl":"10.1016/j.jafrearsci.2025.105789","url":null,"abstract":"<div><div>We report the geochemical composition of a 13 m deep core (Core SAQA 22) drilled in the Saqqara-Memphis floodplain, as well as the isotopic ratios (δ¹³C and δ¹⁸O) of freshwater <em>Corbicula</em> shells. Core SAQA 22 consists mainly of Middle - Late Holocene floodplain sediments (units II-VI) that unconformably overly Late Pleistocene sand and gravel (Unit 1). The findings show variations in δ¹⁸O and δ¹³C values, suggesting intermittent periods of high evaporation/precipitation ratios and moister environments during the Middle Holocene. Due to the prevalence of dry conditions than what exists today, the δ¹⁸O enrichment and mild δ¹³C depletion in the upper part of the core point to less productive paleoenvironments during the Late Holocene. The consecutive climatic variations experienced in ancient Egypt, as deduced from the Saqqara-Memphis floodplain, are outlined as follows: (1) the Predynastic period (7–5.2 kyr cal BP) is generally wet; (2) the Old Kingdom (5.2–4.2 kyr cal BP) had dry local climate conditions for the first half of its existence, which later became wetter during the Late Old Kingdom; (3) the Old Kingdom ended with a brief period of aridity; (4) the Middle Kingdom (4–3.7 kyr cal BP) had a local climate that was both moist and wet, with a brief dry phase at the end; (5) the New Kingdom ended with dry conditions; (6) the local climate turned arid after the Late Period (3–2.3 kyr cal BP); (7) an arid climate was established in the Nile Basin after 2.7 kyr cal BP, with notable drought periods at 1.2 and 0.6 kyr cal BP.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105789"},"PeriodicalIF":2.2,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144749268","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":"Emergent features in northern Western Desert, Egypt: proxies for progressive uplifting of the Tethys platform and the related palaeoclimate shifts since the latest Cretaceous","authors":"Hanan S. Badawy","doi":"10.1016/j.jafrearsci.2025.105790","DOIUrl":"10.1016/j.jafrearsci.2025.105790","url":null,"abstract":"<div><div>The study elucidates the progressive emergence of the southern Tethys platform in Egypt and the associated palaeoclimatic changes, with a focus on their relevance to regional climatic events from the latest Cretaceous through the Late Eocene. The investigation focuses on shoaling and subaerial exposure features identified near the K/Pg boundary, at the top of the Middle Eocene, and within the Upper Eocene rock succession exposed along the western flank of the Giza Pyramids Plateau, northern Western Desert. Key indicators of subaerial exposure include post- and latest-Cretaceous karst pockets, bauxite-filled karst fissures, terra rossa-rich debris flow deposits, dissolution features, and characteristic patterns of dolostone dissolution and dedolomitization. Furthermore, the presence of a shoaling-upward stacking pattern, characterized by abundant <em>Microcodium</em> aggregates within the mixed siliciclastic-carbonate deposits of the Upper Eocene Wadi Hof Formation, underscores the repeated emergence of the southern margin of the Tethys platform in Egypt during this interval. Following the deposition of Upper Eocene–Lower Oligocene marginal marine facies and a subsequent regression, the study area transitioned into a terrestrial environment. This setting was later shaped by Miocene fluvial systems, which deposited extensive clastic sediments across the region. Since the latest Cretaceous, the northern Western Desert has undergone marked climatic shifts. Initially, warm and humid tropical to subtropical conditions aligns with MECO dominated until the Middle Eocene, as indicated by karstification and pedogenesis features. By the Late Eocene, the climate had transitioned to cooler, arid to semi-arid conditions, evidenced by the presence of <em>Microcodium</em> aggregates, indicators of calcic paleosol formation.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105790"},"PeriodicalIF":2.2,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771448","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":"New materials on the Late Cretaceous (Cenomanian) turtles' assemblages from Bahariya depression, Western Desert, Egypt","authors":"Amr Mohsen Muhammed ,&nbsp;Mohamed K. AbdelGawad ,&nbsp;Ren Hirayama ,&nbsp;Afifi Sileem ,&nbsp;Mohamed F. Aly","doi":"10.1016/j.jafrearsci.2025.105786","DOIUrl":"10.1016/j.jafrearsci.2025.105786","url":null,"abstract":"<div><div>Turtle remains from the Bahariya Formation, which had been discovered earlier by Stromer in 1934, namely <em>Apertotemporalis baharijensis,</em> but unfortunately were destroyed during World War II. The present materials were previously collected from the lower beds of the Bahariya Formation, situated near the southwestern end of Gebel El-Fagga in the northeastern part of the Bahariya Oasis, Western Desert, Egypt. Because the turtles' materials collected from the Bahariya Formation are highly fragmented, further systematic classification is difficult to confirm. The present study confirms the presence of more than one family of turtles in the Bahariya Formation. The collected turtle shell plates reveal three families based on shape and size differences: 1) Araripemydidae, 2) Bothremydidae, and 3) A marine taxon Chelonioidea. The present work records new materials for the testudines taxa and nominates Egypt's oldest known turtle’ lineages.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105786"},"PeriodicalIF":2.2,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722098","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":"The potential of Edge recognition method on the basis of the improved hyperbolic tangent filter applied to potential field data: A case study from Madagascar","authors":"Wen Li ,&nbsp;Wanyin Wang ,&nbsp;Zhongsheng Li","doi":"10.1016/j.jafrearsci.2025.105779","DOIUrl":"10.1016/j.jafrearsci.2025.105779","url":null,"abstract":"<div><div>Edge recognition methods based on gravity and magnetic field data have been widely used, particularly in identifying faults and rock mass boundaries, due to the unique advantages of these methods. The prevailing edge recognition methods often have difficulty in effectively balancing the anomaly amplitudes generated by geological bodies located at different burial depths, resulting in edge recognition results with diminished resolutions. To overcome these problems, we propose a novel edge recognition method (IHRHG) based on the hyperbolic tangent function with regulatory factor <span><math><mrow><mi>α</mi></mrow></math></span> and the regularization derivative of horizontal gradient (RHG) of potential field data. Through synthetic gravity and magnetic model testing, we find that the proposed filter has better performance compared with other commonly used methods, which can balance anomalous signals and avoid the generation of spurious boundaries. Finally, we successfully use the method to study the characteristics of major fault distributions on Madagascar Island and adjacent areas. The effectiveness and practicality of IHRHG filter are demonstrated by evaluating a synthetic example and a real example from Madagascar Island. The main advantage of IHRHG filter is that the method can outline boundaries located at different depths simultaneously, and its detection result is clear and with high resolution and accuracy, while avoiding the generation of false signals.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105779"},"PeriodicalIF":2.2,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696522","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":"Enigmatic encrusting fossils from the middle Devonian of Morocco: A new epibiont or peculiarly preserved ascodictyid microproblematica?","authors":"Michał Zatoń,&nbsp;Jakub Słowiński","doi":"10.1016/j.jafrearsci.2025.105784","DOIUrl":"10.1016/j.jafrearsci.2025.105784","url":null,"abstract":"<div><div>Devonian was a special time during which the sea floors were covered by numerous hard substrates, which provided the settlement of various encrusting and boring organisms. Although many of them are well-recognized and have their representatives in younger systems, some have still unresolved taxonomic affinities and thus represent problematic taxa. Here we present intriguing microfossils encrusting a brachiopod shell derived from the Middle Devonian carbonates of the Mader Basin, eastern Anti-Atlas, Morocco, which haven't been reported so far. The fossils have elongated, ribbon-like morphologies with characteristic lateral, tubular branches and are preserved as Fe-oxides/hydroxides casts after pyrite. The best-preserved specimens alone could have easily been taken as some completely new encrusting taxa. However, their association with some ascodictyids, a group of <em>incertae sedis</em> encrusters, and the presence of similar, but much less well-preserved branches located nearby on the same shell or occurring on other shells may indicate that the fossils described, may in fact only represent a differently preserved ascodictyid. If so, the fossils described suggest, that the same encrusting taxon may produce different taphomorphs even on the same small-sized substrate. Thus, finding such fossils alone may unnecessarily increase the diversity of the hard substrate community unless detailed and critical comparisons are made.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"231 ","pages":"Article 105784"},"PeriodicalIF":2.2,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680186","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}