Journal of African Earth Sciences最新文献

{"title":"Ecological differences in upper Pliensbachian (Early Jurassic) reef communities determined by environmental conditions in carbonate settings","authors":"Travis Stone ,&nbsp;Rowan Martindale ,&nbsp;Stéphane Bodin ,&nbsp;Bernard Lathuilière ,&nbsp;François-Nicolas Krencker ,&nbsp;Tanner Fonville ,&nbsp;Lahcen Kabiri","doi":"10.1016/j.jafrearsci.2025.105547","DOIUrl":"10.1016/j.jafrearsci.2025.105547","url":null,"abstract":"<div><div>Reef communities changed dramatically during the Early Jurassic as they recovered from the End-Triassic Mass Extinction. The Atlas Rift Zone in Morocco provided expansive shallow water substrate, which allowed a variety of reef communities to develop, such as lithiotid bivalves that established themselves as new and prolific reef builders alongside corals, microbialites, and sponges in the Sinemurian and Pliensbachian stages. To better understand the dynamics between these reef builders and their environments, a detailed facies analysis of upper Pliensbachian reefs and a quantitative analysis of their composition was undertaken. We describe two distinct environmentally controlled reef types in the Central High Atlas Mountains. Lithiotid bivalves dominated reef construction in lagoonal environments and, together with phaceloid corals, commonly built bioherms and biostromes that ranged from 1 to 2 m tall and up to several hundred meters wide. Meanwhile, on the platform edge, microbialites, corals, and sponges constructed patch reefs up to 7 m tall and 20 m wide. These two reef types share common facies, as many of the same reef inhabitants, and some framework builders, grew in both environments. Despite the facies overlap, the communities in these two environmental settings are distinct, which is likely a result of environmental controls on the dominant reef framework builders. Moderately turbid waters and soft substrate in lagoons were ideal conditions for lithiotids but excluded many corals, sponges, and microbialites. Conversely, the clear, oligotrophic waters at the platform edge allowed photosynthetic and photosymbiotic organisms to thrive (e.g., coral and microbial reefs), while firmer substrate and higher wave energy may have prevented lithiotids from establishing dense populations.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105547"},"PeriodicalIF":2.2,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171379","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":"Lithostratigraphy of the Katangan supergroup in the Kalindi-Kipushi area at the DRC-Zambia border and its relationship to lithostratigraphic successions in other portions of the central African copperbelt","authors":"Helen C. Twigg,&nbsp;Murray W. Hitzman","doi":"10.1016/j.jafrearsci.2025.105545","DOIUrl":"10.1016/j.jafrearsci.2025.105545","url":null,"abstract":"<div><div>This study describes the lithostratigraphy of the Katangan Supergroup from the Kansuki Formation of the Roan Group to the Kanianga Formation of the Kundelungu Group in the Southern Congolese Copperbelt (CCB) in the area south of the Kipushi mine. The study utilises information from diamond drill holes as well as information on the lateral extent of lithostratigraphic units from a new map of the area constructed from both geophysical and geochemical data. A lithofacies analysis approach is used to better understand depositional environments and controls on sedimentation. Facies variability and unconformities in the study area are related to active rifting and eustatic controls during deposition of the Mwashya and Muombe subgroups and a combination of thermal subsidence, salt withdrawal, and global eustatic controls during deposition of the Bunkeya and Gombela subgroups. Comparisons of the study area with areas to the north suggest they were separated by a structural high present from at least the time of deposition of the upper Mwashya Subgroup. The study area appears to exhibit deeper water facies than those of the comparable sequence present in the Zambian Copperbelt.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105545"},"PeriodicalIF":2.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100087","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":"Characterization and evolution of a retrograding-prograding deltaic system, NE Sirte Basin, north-central Libya — Sequence stratigraphic architecture and controlling factors","authors":"Muneer Abdalla ,&nbsp;Husamaldeen Zubi ,&nbsp;Abdalla Abdelnabi","doi":"10.1016/j.jafrearsci.2025.105558","DOIUrl":"10.1016/j.jafrearsci.2025.105558","url":null,"abstract":"<div><div>This study presents the first deltaic system interpreted from three-dimensional seismic and wireline log data in the Sirte Basin, the largest sedimentary basin in Libya and most producing petroliferous basin in Africa. The research focuses on examining the internal sedimentary configuration and sequence stratigraphic architecture of an Oligocene deltaic system in the northeastern part of the Sirte Basin. Three major log facies were defined on the basis of wireline log responses: sandstone, siltstone, and shale. The deltaic system was subdivided into three sedimentary facies based on interpreted log facies and their vertical stacking patterns, seismic geometries, and position along the depositional profile. Those facies are distributary channel, delta front, and prodelta. Three major synchronous and regional stratigraphic surfaces were delineated, encompassing the whole study focus and extend beyond the boundaries of the 3D seismic survey. The deltaic system forms a third-order depositional sequence that is bounded by two unconformable sequence boundaries from below and above. It consists of two system tracts separated by a maximum flooding surface: a transgressive systems tract at the base capped by a regressive systems tract. The deltaic sequence is further subdivided into eleven fourth-order sequences. The development of the deltaic system was mainly controlled by sea-level changes and sediment influx. The deltaic system retreated to the south due to a rise in sea level, reduction in sediment input, with a minor contribution of subsidence resulting from sediment loading. While the progradation occurred as a result of increasing sediment influx that exceeded the creation rate of accommodation space. Additionally, the study provides insights onto the sedimentary and sequence stratigraphic structure, depositional mechanisms, and development of deltaic systems during a stable, post-rift stage of a sedimentary basin.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105558"},"PeriodicalIF":2.2,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100090","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":"Petrogenesis of basalt and associated silicic rocks from upper Omo valley volcanic section, southwestern Ethiopia","authors":"Getnet Assefa ,&nbsp;Demise Tadessa ,&nbsp;Negedie Abrha ,&nbsp;Geremu Fufa ,&nbsp;Andualem Getaw","doi":"10.1016/j.jafrearsci.2025.105546","DOIUrl":"10.1016/j.jafrearsci.2025.105546","url":null,"abstract":"<div><div>Field, petrography, major and trace element analyses of mafic and silicic rocks from upper Omo valley volcanic section, Southwestern Ethiopia are presented to determine petrogenetic evolution. The analyzed rocks belong to the basaltic and rhyolitic suites within the sub-alkaline group and these suites are linked via fractional crystallization as evidenced by occurrence of intermediate rocks (basaltic andesite and andesite rocks). Plagioclase, pyroxene, and Fe–Ti oxide minerals are the prominent phenocryst in basaltic rocks, while alkali feldspar phenocrysts are abundant in rhyolitic rocks. Major element correlations indicate fractional crystallization played a significant role in the evolution of the upper Omo volcanic rocks. The rhyolitic rocks show general enrichment of light rare earth element (LREE) and depletion of heavy rare earth element (HREE), strong negative anomalies in Sr, P and Ti, and low Ba/Nb, La/Nb,and Th/Nb ratios indicate that they were formed through low-pressure fractionation of basaltic lava derived from the depleted mantle with unremarkable crustal input. Correspondingly, REE abundances and incompatible trace element (e.g., Zr/Nb, Nb/Y ratios as well as plots of Nb/Yb vs. Th/Yb) suggest that rhyolite rocks were derived from basalt magma source which resemble ocean island basalt (OIB)-like magma. The source area features and the similarity of melting conditions suggest that the ascent and development of mantle diapirs is the key to elucidate the volcanic activity in the upper Omo valley volcanic section. The geochemical features of the volcanic rocks found in the upper Omo valley volcanic section are similar to those found in the northwest Ethiopian plateaus (such as LT and HT1-type basalt, Lima Limo and Wegel Tena rhyolitic ignimbrite). However, the crustal materials involvement in the genesis of LT-type basalt and Lima Limo rhyolite, Northwestern Ethiopian plateau were determined (Pik et al., 1998, 1999; Ayalew and Yirgu, 2003).</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105546"},"PeriodicalIF":2.2,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171378","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":"Groundwater recharge zone mapping in a coastal mediterranean aquifer applying fuzzy and analytical hierarchy process and frequency ratio: A case study of northeast Tunisia","authors":"Amal Kouaied ,&nbsp;Mohamed Haythem Msaddek ,&nbsp;Adel Zghibi ,&nbsp;Aziza Barrek ,&nbsp;Séverin Pistre ,&nbsp;Ismail Chenini","doi":"10.1016/j.jafrearsci.2025.105537","DOIUrl":"10.1016/j.jafrearsci.2025.105537","url":null,"abstract":"<div><div>Global water stress, driven by demographic growth, climate change, industrialization, and agricultural development, is exacerbated by excessive groundwater extraction, depleting aquifer storage. Groundwater recharge is crucial for ensuring water sustainability and preserving coastal water resources. This study assess aquifer suitability zones of the Aoussja Ghar El Melh coastal region in Tunisia using geographic information techniques (GIS), and three numerical methods: Fuzzy Logic, Analytical Hierarchical Process (AHP) and Frequency ratio (FR) method. The aim is to delineate significant groundwater recharge areas. The findings reveal three distinct recharge capacity classes. Fuzzy Logic indicated that a approximately 72 % of the study area, characterized by lithological features like sandstone alluvium and sandy marly soils in central plains, is suitable for groundwater potential zones (GWPZ). In contrast, the AHP indicates about 79% of the area, while FR model indicates 48%. These variations are influenced by the region's lithological and hydrogeological characteristics. Validation against 22 well locations show AHP as the most accurate (AUC = 91%), followed by Fuzzy Logic (AUC = 86 %) and the FR model (AUC = 70%). The application of the Fersi equation shows a strong correlation and spatial distribution similar to the AHP approach. This study concludes that while the Fuzzy Logic and FR models are valid for identifying GWPZ, they are less effective than AHP method, which provides refined recommendations for selecting recharge sites. Environment risks such as groundwater contamination and salinization in agricultural areas highlight the need for land resources management. The final map serves as a guideline for planning aquifer recharge projects and emphasizes the necessity of regulations and pumping limits to prevent overexploitation and saltwater intrusion. This preliminary assessment underscores the importance of implementing protective measures and recharge programs.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105537"},"PeriodicalIF":2.2,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100089","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":"Implementation of machine learning predictive models for targeting gold prospectivity mapping in part of the Ilesha schist belt, southwestern Nigeria","authors":"Ajibola Richard Faruwa ,&nbsp;Jing Ba ,&nbsp;Wei Qian ,&nbsp;Uti Ikitsombika Markus ,&nbsp;Imane Bachri","doi":"10.1016/j.jafrearsci.2025.105543","DOIUrl":"10.1016/j.jafrearsci.2025.105543","url":null,"abstract":"<div><div>This research leverages innovative machine learning techniques, including artificial neural networks(ANN), support vector machines(SVM), random forests(RF), and Naïve Bayes(NB), to construct a predictive model for gold deposits in part of the Ilesha schist belt. Thirteen predictor maps were used from geophysical, remote sensing, and geological datasets highlighting essential processes in ore formation, such as source characteristics, transport mechanisms, and chemical deposition. Together with 35 gold deposits and non-deposit locations, these datasets were employed to train and test the machine learning models using 10-fold cross-validation techniques. Performance was evaluated with confusion matrices, statistical metrics, and receiver operating characteristic (ROC) curves. All models achieved high predictive accuracy: RF at 98.94%, ANN at 97.80%, SVM at 93.65%, and NB at 90.48%. Key localization factors include magnetic lineament density, structural complexity, SRTM lineament density, analytical signals, and Bouguer gravity anomalies. Using the trained models, prospectivity maps were created, highlighting areas of very-high, high, moderate, and low potential for further research. The Prediction-Area for all the models exceeded 78%, confirming their effectiveness in identifying significant gold deposits in the area. Euler deconvolution suggests geological influences from sill/dyke structures, with magnetic source depths from &lt;-12.96 m to &gt; - 801.67 m and from &lt; −30.82 m to &gt; -1053.94m for structural indices (SI) of 0.5 and 1, respectively while spectral analysis indicates depths of 100m to 1.1 km for shallow sources. A strong correlation exists between gold prospectivity and magnetic sources below 300 m, especially near the Iwaraja/Ifewara fault and lithological boundaries. This study highlights the effectiveness of machine learning models in gold exploration and suggests avenues for future research in similar geological contexts.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"225 ","pages":"Article 105543"},"PeriodicalIF":2.2,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419527","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":"Genesis of the Hamash gold deposit, eastern desert, Egypt: Inferences from new studies on mineral chemistry and fluid inclusions","authors":"Islam.A. Dourgham ,&nbsp;Safwat S. Gabr ,&nbsp;Lin-Fei Qiu ,&nbsp;Masoud A. Omar ,&nbsp;Fatma Deshesh","doi":"10.1016/j.jafrearsci.2025.105544","DOIUrl":"10.1016/j.jafrearsci.2025.105544","url":null,"abstract":"<div><div>In the South-Eastern desert of Egypt, where gold mineralization is hosted by granites, the Hamash gold deposit is recognized as one of the pharaoh's mines. In this study, the present authors aimed to study the paragenesis of sulfide minerals and the genesis of the related gold deposit based on field observation, ore mineralogy, electron probe analysis, and fluid inclusion data. The result was that the granitoid rocks of the Hamash area, composed mainly of granite and granodiorite, covered the center and southern portions of the study area and intruded into the metavolcanics. The Hamash gold deposit is hosted by intensely deformed granitic rocks that are dissected by numerous gold-bearing sulfide-quartz veins. The abundant ore minerals include pyrite, sphalerite, galena, and chalcopyrite (±tetrahedrite and ±gold disseminations), which occur in crosscutting quartz veins. Gold is associated with sulfides in quartz veins and alteration zones. The results of electron probe microanalysis (EMPA) reveal three varieties of pyrite with low As content (Py1 and Py2) and high As content (Py3) that were replaced by galena ± gold. Gold occurs either as clusters of tiny gold grains included in pyrite or as streak-like small inclusions within goethite. The new microthermometric and laser Raman spectroscopy studies indicate that the gold-bearing quartz veins are characterized by two types of fluid inclusions: H₂O-NaCl and H₂O-CO₂-NaCl. The lithostatic and hydrostatic pressure gradients in the isochores of the two types of fluid inclusions indicate fluid entrapment and gold deposition at temperatures between 235 °C and 270 °C at pressures ranging from 1.6 kbar to 2.7 kbar with low to moderate salinity of ∼2–7 eq. mass % NaCl of aqueous-carbonic fluid during the transition from lithostatic to hydrostatic conditions. Based on all the author's observations and conditions of ore formation, we suggest that the Hamash gold deposit is related to porphyry-type and epithermal sulfide deposits.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105544"},"PeriodicalIF":2.2,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171382","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":"Bartonian coral biostromes in a storm-dominated ramp setting of the El-Ramliya-Akheider block: sedimentology, sequence stratigraphy and regional paleogeographic insights, Cairo-Sukhna region, Egypt","authors":"George Henry,&nbsp;Mounir El-Azabi,&nbsp;Walid Kassab","doi":"10.1016/j.jafrearsci.2025.105542","DOIUrl":"10.1016/j.jafrearsci.2025.105542","url":null,"abstract":"<div><div>Scleractinian coral reefs are pivotal carbonate producers in the late Cenozoic era, they are useful in understanding the early Paleogene thermal events. Despite challenges in studying the Eocene due to scarce data and poor outcrop quality, the El-Ramliya-Akheider block has provided critical insights into its Bartonian carbonate succession. The succession is characterized by extensive coral carpets (biostromes) and a wide range of sedimentary structures, including large-scale channels. To investigate the facies organization and sedimentary pattern of the succession, we integrated sedimentological (outcrop studies, facies analysis) and paleontological approaches. <em>Acropora</em> coral carpets, which thrived in mid-ramp settings, have been altered by sedimentological changes caused by storm currents. The inner ramp environment with bioshoals of larger miliolids and seagrass meadows shows a rhythmic intercalation pattern with biostromes. This intercalation, along with the formation of channels filled with carbonate fragments, is influenced by the dynamic interplay of storm-driven currents and return currents. The presence of coral fragments (coralline float-/rudstone) as para-to allochthonous accumulations suggests that coral colonies initially grew as carpets in a calm, mid-ramp environment. These fragments were subsequently transported and redeposited during storm currents. The return currents generated channel deposits (abraded foraminiferal pack-/grainstone) characterized by large-scale cross-beddings. These channels, filled with inner-ramp foraminiferal pack-/grainstone, were scoured into the mid-ramp coral biostromes, highlighting the significant role of storm-related processes in sediment transport and channel formation. Notably, coral biostromes in a stable, euphotic mid-ramp setting mark the earliest recovery during the Bartonian cooling period after the Middle Eocene Climatic Optimum event (MECO). The dominance of Bartonian lagoonal marine conditions in the Cairo-Sukhna region is attributed to global transgression, shallow depositional basin, and restricted water circulation caused by uplifted barriers. Overall, this study enhances understanding of the Eocene paleoenvironment and the capability of coral ecosystems.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105542"},"PeriodicalIF":2.2,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100088","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":"K-Pg transition in neritic limestones: Deciphering the first bio/chemo-stratigraphic records and tectono-sedimentary evolution, eastern Neotethys (NE Türkiye)","authors":"Fatih Köroğlu ,&nbsp;Bilal Sarı ,&nbsp;Raif Kandemir ,&nbsp;İsmail Ömer Yılmaz ,&nbsp;Sacit Özer","doi":"10.1016/j.jafrearsci.2025.105540","DOIUrl":"10.1016/j.jafrearsci.2025.105540","url":null,"abstract":"<div><div>Interestingly, the K-Pg transition from the Cretaceous to the Paleogene is the closest to our time and, from today's perspective, the most dramatic extinction that has ever occurred on Earth. Using different methods and lithologies, K-Pg transition records have been identified in different areas around the Earth. In this study, the neritic carbonate successions in the arc sedimentary cover of eastern Neotethys (Eastern Sakarya Zone, NE Türkiye) were studied using high-resolution bio-chemo/stratigraphy and sedimentary geology methods. The Ziyarettepe Formation, which is the subject of this study, is characterized by its neritic and hemipelagic sedimentary features. Notwithstanding, the clastic and irregular distribution of macro- and microfossils in the Ziyarettepe Formation was realized in parallel with sea level changes, regional tectonism, and global event effects. As a result of these events, the shell structure of the fossils shows the processes of transport from shallow habitats, transport to the platform-platform edge-slope edge, and deposition under these conditions. On the other hand, the neritic and hemipelagic limestones of the Ziyarettepe Formation allow the study of benthic and planktonic foraminifera biostratigraphy, as well as other fossil groups in the stratigraphic interval around the K-Pg transition. According to the results, the stratigraphic age of the Ziyarettepe Formation is given as late Campanian-Thanetian, both chemostratigraphically and biostratigraphically (mainly foraminifera). The Ziyarettepe Formation (Tosunlu Tunnel) stratigraphic section was examined for stable δ¹³C and δ¹⁸O isotopes, rare earth elements, and whole rock carbonate geochemistry records within the Ziyarettepe Formation. Geochemical trends across the K-Pg transition are distinguished by anomalies resulting from many impact signals, including mainly the Deccan Traps and the Chicxulub Impact. The geochemical profile of the K-Pg transition was influenced by paleoenvironmental impacts, as in this example of a neritic succession in the eastern Neotethys. Together with multi-chemostratigraphic analyses, it could be shown for the first time that the K-Pg transition was also recorded in this basin. According to the tectono-sedimentary evolution in the region, these neritic successions were deposited in a back-arc environment during the northward subduction of the northern branch of Neotethys.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105540"},"PeriodicalIF":2.2,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100091","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":"Provenance and source area weathering of sandstones from the Tarkwaian Group at the northeastern extent of the Paleoproterozoic Ashanti Belt, Ghana: Constraints from petrography and geochemistry","authors":"Victor Sedziafa ,&nbsp;Ying Song ,&nbsp;Emmanuel Daanoba Sunkari ,&nbsp;Daniel Kwayisi ,&nbsp;Chris Y. Anani ,&nbsp;Daniel K. Asiedu","doi":"10.1016/j.jafrearsci.2025.105536","DOIUrl":"10.1016/j.jafrearsci.2025.105536","url":null,"abstract":"<div><div>An integrated geochemical and petrographic study was conducted on the Paleoproterozoic sandstones of the Tarkwaian Group exposed at the northeastern extent of the Ashanti Belt, Ghana. Recognizing the economic importance of the Tarkwaian Group, particularly owing to its extensive gold deposits, the primary objective was to investigate the provenance, tectonic setting, and crustal evolution of the Tarkwaian Group. The dominant quartz (polycrystalline and monocrystalline), together with minor muscovite, feldspar, hematite, and lithic fragments, characterize the sandstones and thus, the sandstones are classified as sublitharenite, and lithicsubarkose. Based on mineralogical composition and major element content, the sandstones can be classified as litharenite, sublitharenite, and minor greywacke. The high values of SiO₂/Al₂O₃ (average: 12.74), relatively moderate values of K₂O/NaO₂ (average: 1.42), and high quartz content (average: 88%) suggest that the sediments are compositionally sub-mature to mature. The sandstones likely underwent low to moderate levels of sedimentary sorting and recycling owing to angular to sub-rounded grains and moderate Zr/Sc and Th/Sc values. The high Chemical Index of Alteration (CIA) signature (average: 76.79 wt%), Plagioclase Index of Alteration (PIA) values (average: 90.13 wt%), and Index of Compositional Variability (ICV) (average: 0.61 wt%) suggest moderate to intense chemical weathering within the region of origin. Overall, the mineralogical and geochemical features of the sandstones, such as a high proportion of quartz and feldspar, and elevated concentrations of elements such as Zr, Sc and Th, and moderate to high ratios of Al₂O₃/TiO₂ and La/Sc indicate that they were likely sourced from felsic to intermediate igneous rocks and deposited in an active continental margin such as magmatic arc setting.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"224 ","pages":"Article 105536"},"PeriodicalIF":2.2,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143171381","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}