Journal of African Earth Sciences最新文献

{"title":"Zircon trace element geochemistry of the neoarchaean late-granite suites along the southern margin of the Zimbabwe craton, Zimbabwe","authors":"Godfrey S. Chagondah ,&nbsp;Marlina A. Elburg ,&nbsp;Axel Hofmann ,&nbsp;Hugh Rollinson ,&nbsp;Henriette Ueckermann ,&nbsp;Clarisa Vorster","doi":"10.1016/j.jafrearsci.2025.105619","DOIUrl":"10.1016/j.jafrearsci.2025.105619","url":null,"abstract":"<div><div>In-situ laser ablation quadrupole inductively coupled plasma mass spectrometry (LA-Q-ICP-MS) analyses of zircon grains from the ca. 2635–2620 Ma Chilimanzi and Razi granite suites along the southern margin of the Zimbabwe Craton in Zimbabwe reveal that a majority of zircons experienced post-magmatic chemical alteration. A minority (5 %) of the analyses show unaltered (<em>Type-1</em>) patterns. <em>Type-1</em> zircons show low abundances of light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and they preserve igneous zoning textures. The majority of the grains analysed exhibit altered (<em>Type-2</em>) patterns indicated by overabundance in LREE concentrations and such grains are partially or completely metamict (radiation damaged). <em>Type-2</em> grains experienced radiation damage due to high initial contents of radioactive elements including U and Th incorporated at the time of crystallization. The structurally defective zircons experienced pervasive chemical alteration from <em>Type-1</em> to <em>Type-2</em> compositions via susceptible regions such as fractures under fluid-mediated conditions. Lack of analyses with Th/U ≤ 0.08, which is a diagnostic feature of zircons precipitated from hydrothermal-melts supports the view that <em>Type-2</em> compositions derived from alteration of <em>Type-1</em> zircons. LREE overabundance in the zircon suites is also explained by inadvertent analysis of mineral inclusions and/or contaminants such as Fe, Ti, and Mn oxides along fractures.</div><div>Our study established a LREE index, LREE-I = 32 as a discriminant for altered and unaltered zircon analyses. LREE-I &lt; 32 (altered compositions) correlates with known alteration features such as cathodoluminescence dark core domains, partial or complete overprint of igneous textures in fluid-mediated conditions, overabundance in LREE, and high contents of non-structural elements in zircon such as Ti, Li, Th and U. The Ti-in-zircon thermometry on unaltered analyses of the Chilimanzi Suite's Great Zimbabwe granite constrains the crystallization temperature at 698–738 °C, consistent with temperatures at zircon saturation for felsic magmas. Our study emphasizes that zircon chemistry is a pre-requisite data layer that should be incorporated in analytical protocols to complement conventional, discordance-based data filter for effective screening of U-Pb analyses for age determinations.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105619"},"PeriodicalIF":2.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying dynamic source and ground motion parameters for earthquakes bigger than 3.0 in Aswan region, southern Egypt","authors":"Hamada Saadalla ,&nbsp;Saleh Qaysi ,&nbsp;Abdalla Abdelnabi ,&nbsp;Mona Hamada","doi":"10.1016/j.jafrearsci.2025.105643","DOIUrl":"10.1016/j.jafrearsci.2025.105643","url":null,"abstract":"<div><div>The dynamic source parameters of earthquakes with local magnitudes <span><math><mrow><msub><mi>M</mi><mrow><mi>L</mi><mspace></mspace></mrow></msub><mo>≥</mo></mrow></math></span> 3.0, recorded by the Aswan seismic broadband network between 2010 and 2024 in the Aswan region of southern Egypt, have been estimated. A spectral inversion method was applied to separate the source, receiver, and path effects from the observed displacement spectra using linear least squares analysis with a reference site. Initially, the attenuation effects along the ray path and site-specific effects were removed to derive the source spectra for each event. The Brune model was then employed to estimate the dynamic source parameters and their scaling relationships using S-wave displacement source spectra. From the derived displacement spectra, we estimated source parameters for each event, including seismic moment, corner frequency, fault radius, and static stress drop. The results indicate that both stress drop and source radius increase with moment magnitude. The observed stress drops for the studied earthquakes range from 0.4 to 4.8 MPa, suggesting that reservoir-triggered earthquakes may exhibit lower stress drops compared to tectonic or crustal earthquakes. The source radius varies from 139.8 to 294.5 m, while the corner frequency decreases with increasing moment magnitude, ranging from 4.3 to 9.0 Hz. To assess earthquake hazards in the Aswan seismic zone and its surrounding areas, stochastic simulation analyses were conducted for earthquakes with local magnitudes <span><math><mrow><msub><mi>M</mi><mrow><mi>L</mi><mspace></mspace></mrow></msub></mrow></math></span> ≥ 3.5 at four sites: New Aswan City, Aswan University, Sahary City, and Kurkur Village. The modeled parameters include peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), and pseudo-spectral acceleration (PSA). The results revealed that the highest PGA (24.2 cm/s²), PGV (0.4 cm/s), and PGD (0.013 cm) were simulated at Aswan University for the earthquake on November 7, 2010, with an epicentral distance of 2 km. Additionally, the highest PSA values were 72.6 cm/s² and 65.9 cm/s² at Aswan University and Sahary City, respectively, for the same event. These findings provide essential insights for evaluating seismic hazards in the Aswan region, contributing to a better understanding of earthquake risks in southern Egypt.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105643"},"PeriodicalIF":2.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738715","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 late Pliocene-Pleistocene transition in North-Eastern Tunisia (Cap Bon Peninsula) as example from the western Mediterranean basins: Paleontological, taphonomical and paleoecological data","authors":"Nadia Gaaloul ,&nbsp;Syrine Ben Ali ,&nbsp;Linda Satour ,&nbsp;Mohamed Soussi ,&nbsp;Jean-Yves Reynaud ,&nbsp;Albert Galy","doi":"10.1016/j.jafrearsci.2025.105644","DOIUrl":"10.1016/j.jafrearsci.2025.105644","url":null,"abstract":"<div><div>Northeastern Tunisia, is part of the Western edge of the Pelagian Mediterranean basins. During the Neogene, it formed a tip of a large embayment where marine, and paralic systems prevailed. The biodiversity analysis of the Piacenzian (MPL 5a<strong>)</strong> and Gelasian (MPL5b and MPL6<strong>)</strong> reveals highly fossiliferous content (ostracods, planktonic foraminifers and oysters). Four oyster species are identified, including <em>Neopycnodonte cochlear</em> and <em>Hyotissa hyotis</em>, newly characterized in the Lobna section. Encrustations on oysters are primarily barnacles, vermetids, bryozoans and juvenile oysters. Facies analysis, taphonomy and ichnology indicate a shift from a quiet offshore muddy environment during Late Pliocene (Top of Sidi Barka Formation = SBF) to a moderate-high energy inner sandy shelf setting in the Early Pleistocene (Hammamet Sandstones Formation = HSF) resulting from the interplay between global sea-level fall, regional cooling and local tectonics related to the alpine phase. The foraminifera and ostracod biostratigraphic revisions, together with the Carbon, Oxygen isotopic composition of the oyster shells show that a major change coincides with the Pliocene-Pleistocene boundary, making the Cap Bon a particularly interesting succession in the local series boundary stratotype.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105644"},"PeriodicalIF":2.2,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143748566","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 object-based classification for geological mapping: Applications to the volcanic region of Vakinankaratra (central Madagascar)","authors":"Frédéric L. Ranomenjanahary ,&nbsp;Feyda Srarfi ,&nbsp;Dieudonné Razafimahatratra ,&nbsp;Dominique Rakotomanana ,&nbsp;Mohamed S. Hamdi ,&nbsp;Riadh Abidi ,&nbsp;Josoa R. Randriamalala ,&nbsp;Najet Slim Shimi","doi":"10.1016/j.jafrearsci.2025.105641","DOIUrl":"10.1016/j.jafrearsci.2025.105641","url":null,"abstract":"<div><div>A geological map is an indispensable instrument in the field of geological research. In the past, the sole method employed for the production of geological maps was manual mapping. This approach is costly in terms of time, resources and the amount of work required. Since the conclusion of the 20th century, remote sensing techniques, which entail the classification of satellite images, have been employed for the purpose of geological mapping to complement field work. The pixel method, which classifies based on pixels, is the most prevalent approach for the production of geological maps due to its greater ease of implementation. In contrast, object-based classification methods which consider sets of pixels (objects), are seldom employed, despite their considerable potential for geological mapping. The aim of this article is to compare the performance of these two types of satellite image classification for the update of geological maps (pixel and object-based method). The Central Highlands of Madagascar region has diverse geological, volcanic, sedimentary and metamorphism formations. The richness of geological features make harder geologic mapping. The use of Sentinel-1 and 2 images was justified by their superior accuracy and a high spatial resolution, permitting an easier details highlighting. The object-based method yielded geological map of notable accuracy, a slight superior Kappa coefficient (0.88 vs. 0.83). The generated map exhibit greater homogeneity and are more readily interpretable. Enabling, more straightforward identification of the different lithologies and easier geodynamic history comprehension of the study area.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105641"},"PeriodicalIF":2.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776859","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":"Comments on the Greenfield (2025)","authors":"Luigi Capasso ,&nbsp;Sayed Abdel Aziz ,&nbsp;Abdel Aziz Tantawy ,&nbsp;Mohamed Kamel Mousa ,&nbsp;Dalia Gamal Wahba ,&nbsp;Gebely Abdelmaksoud Abu El-Kheir","doi":"10.1016/j.jafrearsci.2025.105642","DOIUrl":"10.1016/j.jafrearsci.2025.105642","url":null,"abstract":"<div><div>Greenfield (2025) proposed two taxonomic revisions of the specimens described as <em>Onchopristis</em> sp. ind. by Capasso et al. (2024) from the Maastrichtian of the Dakhla Formation, Egypt. The taxonomic re-determinations proposed by Greenfield (2025) are based on: (i) the rejection (based on a \"pers. obs.\") of the existence of <em>Onchopristis</em> in the Maastrichtian-Paleocene of Mali (reported by O'Leary et al., 2019), (ii) the denial of the correctness of the measurements of a rostrum of <em>Onchopristis</em> (now lost), reported by professor Ernst Stromer (1925), and on (iii) the text and figures by Capasso et al. (2024), without examining the original specimens.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105642"},"PeriodicalIF":2.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738756","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":"Paleoredox conditions and paleoproductivity of the early-Eocene sediments in the Gaga Section, Western Desert, Egypt","authors":"Abdullah Mahmoud ,&nbsp;Chunxia Zhang ,&nbsp;Abdel Aziz Tantawy ,&nbsp;Zijuan Yang ,&nbsp;Hassan Khozyem ,&nbsp;Abdelhamid M. Salman","doi":"10.1016/j.jafrearsci.2025.105640","DOIUrl":"10.1016/j.jafrearsci.2025.105640","url":null,"abstract":"<div><div>The release of massive amounts of greenhouse gases, mainly carbon dioxide and methane, into the atmosphere was assumed to have generated anoxic conditions during the Paleocene-Eocene Thermal Maximum (PETM). These gases caused the globe to warm rapidly and significantly, disrupting ocean circulation patterns and reducing the quantity of oxygen accessible to marine organisms. Herein, detailed geochemical investigations were performed on forty-one cutting samples collected from the Gaga section (Egypt), with an emphasis on total organic carbon (TOC), trace elements, and carbonate content. These geochemical observations revealed important information about paleoredox conditions, marine biological productivity, and processes controlling organic matter accumulation. A sudden decrease in carbonate contents, as well as the scarcity of nannofossils, indicate the severity of the acidification during the onset of the PETM. Abundant framboidal pyrite within foraminiferal shells at the PETM interval indicates the occurrence of sulfur-related processes during diagenesis, a consequence of organic matter decomposition under oxygen-depleted conditions where sulfur-reducing bacteria play a significant role. The ratios of V/(V + Ni), V/Cr, Fe/Ti, P/Ti, Zn/Al, and Ni/Al indicate that the PETM interval was subjected to dominantly anoxic conditions under gradually increasing primary productivity. Conditions were favorable for the formation of the glauconite bed (Bed A) at the onset of the PETM, which represent unique chemical conditions, such as a warm condition, rapid transgression, a reduced sedimentation rate, intensive continental weathering, an enhanced supply of cations, and the existence of anoxic conditions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105640"},"PeriodicalIF":2.2,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738820","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":"Tidal facies analysis and 3D static modeling of the Cenomanian Lower Bahariya reservoir, Qasr Field, North Western Desert, Egypt","authors":"Mohamed Heneish ,&nbsp;Abdel Moneim El-Araby ,&nbsp;Ahmed N. El-Barkooky ,&nbsp;Raed Badr","doi":"10.1016/j.jafrearsci.2025.105638","DOIUrl":"10.1016/j.jafrearsci.2025.105638","url":null,"abstract":"<div><div>Facies heterogeneity of the Lower Bahariya sandstone reservoir in the Qasr Field led to challenges in the hydrocarbon exploration and field development. In this study, we integrated sedimentological and petrophysical analysis of conventional core data and wireline logs to construct a 3D static model that predicts the reservoir facies and properties variations in the study area. Detailed sedimentary facies analysis allowed to define eleven sedimentary facies types of three main facies associations: tidal channel, tidal sand bars, and tidal flat complex including bioclastic carbonate accumulations. These facies developed within a transgressive tide-influenced estuarine system. Porosity-permeability data of the interpreted facies reveals that both the tidal sand bars and channels are of good reservoir quality in comparison to the tidal flat heterolithics, and the carbonates that are non-reservoir facies. Both the lower parts of the tidal sand bars and the upper parts of the tidal channels show a relatively lower reservoir quality (ɸ&lt;13 %, K &lt; 1mD) due to increased argillaceous and calcareous cement content. Spatial distribution of the reservoir properties in the 3D geo-cellular static model confirms that the main producing tidal sand bars extend NW-SE, parallel to the fault system. These bars have an excellent reservoir quality in the west that deteriorates towards the east associated with facies change to heterolithic tidal flat facies. Hydrocarbon accumulation was identified within the central part of the study area, particularly within the tidal sand bar facies. The findings of this study shed light on the Lower Bahariya lateral and vertical reservoir distribution and quality, reducing uncertainty in the field development, and providing applicable knowledge for similar heterogeneous tidal hydrocarbon reservoirs.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105638"},"PeriodicalIF":2.2,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768304","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":"High-resolution sequence stratigraphy and microfacies analysis of the lower part of the Sa'di Formation in selected wells from the West Qurna oilfield, southern Iraq","authors":"Maher J. Ismail ,&nbsp;Maher M. Mahdi ,&nbsp;Frank R. Ettensohn ,&nbsp;Rafea A. Abdullah ,&nbsp;Amna M. Handhal ,&nbsp;Alaa M. Al-Abadi","doi":"10.1016/j.jafrearsci.2025.105639","DOIUrl":"10.1016/j.jafrearsci.2025.105639","url":null,"abstract":"<div><div>Tectonic and eustatic changes have had major impacts on the Cretaceous stratigraphy and its hydrocarbon potential in southern Iraq, and the Sa'di Formation is one of several Cretaceous carbonate plays that reflect these types of changes. To further examine the influence of these impacts, thin sections from cores, as well as wireline and image logs, from the lower part of the Sa'di Formation in four wells from the West Qurna Oilfield were examined. Wackestone, packstone, grainstone and floatstone microfacies groups were identified and subdivided into ten submicrofacies. The microfacies were deposited at several environments such as open marine, restricted and outer ramp, as well as to position in transgressive and highstand sequence tracts in two fourth-order parasequences. Moreover, microfacies were compared with Formation Microresistivity image (FMI) logs and show that image logs can be used to recognize microfacies and their likely environments. Integration of these analyses with paleogeography and regional tectonics suggests that the lower Sa'di Formation reflects early deposition in a newly formed foreland basin that represents ongoing subsidence accompanying collision and closure of the Neo-Tethys Ocean. The carbonate-rich nature of the unit is linked to deposition on the distal margin of the foreland basin in an arid climate, while cyclicity in the unit represents both tectonic and eustatic fluctuations.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"228 ","pages":"Article 105639"},"PeriodicalIF":2.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760665","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":"Calcareous nannofossil biostratigraphy and paleoecology of the Maastrichtian– Paleocene deposits in southern Tethys: “a case study from the upper Nile Valley (NE Africa)”","authors":"Mohamed Youssef ,&nbsp;Sherif Farouk ,&nbsp;Saida Taha","doi":"10.1016/j.jafrearsci.2025.105637","DOIUrl":"10.1016/j.jafrearsci.2025.105637","url":null,"abstract":"<div><div>The current study focuses on the biostratigraphy and paleoecology of calcareous nannofossils within the Maastrichtian–Paleocene sequences of southern Tethys, specifically in three land sections of the upper Nile Valley of Egypt (NE Africa). The sections (from north to south) are Gabal El-Borga, Gabal El Sharawna, and Gabal El Nezzi sections. The sequence was represented by the Dakhla, Kurkur, Tarawan, Garra, and Esna formations. The main goal is the biostratigraphy and Paleoecology of calcareous nannofossils within the Maastrichtian - Paleocene of southern Tethys, specifically in three land sections of the upper Nile. Examination of calcareous nannofossils resulted in the identification of 40 species of 30 distinct genera. The biostratigraphic analysis of the calcareous nannofossils was summarized as follow: CC23, CC24, CC25 (Maastrichtian) and NP2, NP3, NP4, NP5, NP6, NP7/8, NP9 (Paleocene). The NP4 Zone was divided into six zones and subzones (NTp6, NTp7A, NTp7B, NTp8A, NTp8B, and NTp8C). Absences of CC26 and NP1 biozones refer to a hiatus between the Cretaceous/Paleogene (K/Pg) interval. The Danian–Selandian boundary is characterized by the appearance of <em>Lithoptychius ulii</em>, <em>L. pileatus</em>, and <em>L. janii</em>, which marks the second radiation of <em>Fasciculithus</em>. Maastrichtian in the study area was characterized by tropical flora, which indicates low surface water fertility. Taxa from warm-water oligotrophic habitats were prevalent in the Paleocene stratigraphic sequences of the research region.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105637"},"PeriodicalIF":2.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143714335","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":"Petrography, geochemistry and geochronology of Aghirer Plutonic Granitoid Complex, Eastern Hoggar, Algeria","authors":"Hocine Zeghouane ,&nbsp;Abla Azzouni-Sekkal ,&nbsp;Jean Paul Liégeois ,&nbsp;Ahmed Serkhane","doi":"10.1016/j.jafrearsci.2025.105630","DOIUrl":"10.1016/j.jafrearsci.2025.105630","url":null,"abstract":"<div><div>The Assodé-Issalane terrane, situated in the southern region of Algeria, east of the Hoggar, is predominantly composed of Paleoproterozoic metamorphic rocks which were subjected to high-grade amphibolite to granulite facies metamorphism during the Pan-African orogeny, accompanied by large migmatization and granite emplacement. The easternmost region of the Raghane-8°30 shear zone exhibits evidence of the Eburnean orogeny (2.2–2.0 Ga) and multiple granitoid events, indicative of three major orogenic episodes: 800–820 Ma, extensional event (790, 730 Ma), a collision with the West African craton (660 Ma and 630-580 Ma), and a subsequent collision with the Murzuq craton (575-545 Ma), culminating in the regional metamorphism and stabilization of the eastern Hoggar. The present study focuses on the Aghirer Granitic Pluton (AGP), a late, circular granite intrusion that intrudes the 730 Ma Arirer granitic batholith and the Eberjegui basement of the Tadoumet region. A comprehensive suite of analytical techniques was employed, encompassing petrographic examination, geochemical assessment on ten samples obtained from the AGP, and Rb/Sr isotopic geochronological analysis on seven samples. Petrographic and geochemical analyses reveal a potassic calc-alkaline granite and granodiorite composition, suggesting a syn-collisional to late orogenic tectonic setting. Geochemical data indicate its affinity with the lower continental crust with minimal crustal contamination. Rb-Sr geochronology yielded an isochron age of 553 ± 20 Ma, recording the late Pan-African orogeny. The low initial ⁸⁷Sr/⁸⁶Sr ratio further supports the limited role of upper crustal contamination in the magma genesis. These findings provide crucial insights into the magmatic evolution and tectonic history of the Hoggar during the late Pan-African orogeny.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"227 ","pages":"Article 105630"},"PeriodicalIF":2.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680606","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}