Journal of African Earth Sciences最新文献

{"title":"Flood hazard in Malawi","authors":"M. Garcin ,&nbsp;H. Mdala ,&nbsp;Y. Kalebe","doi":"10.1016/j.jafrearsci.2024.105490","DOIUrl":"10.1016/j.jafrearsci.2024.105490","url":null,"abstract":"<div><div>This article presents the methodology and key findings of the first national study of flood hazard conducted across Malawi as part of the 2016–2021 GEMMAP programme. After outlining Malawi's geomorphological, climatic, and hydrographic features, we detail the approach used for flood hazard assessment and mapping. Ten flood types were identified, reflecting diverse morphological, geological, and climatic settings, resulting in flood hazard maps, which cover the entire country and highlight areas at risk based on flood type and magnitude. The total area exposed to flooding in Malawi is estimated at 16% of the country's surface area (around 15 000 km2). Flooding of plains along major rivers, such as the Shire River, which affects hundreds of thousands of people, accounts for approximately 37% (5100 km²) of Malawi's flood-prone areas. Flooding in dambo areas comprise 34% (4700 km²), and lake shores another 10% (1400 km²). Although debris flow flooding is restricted to around 4.2%, it nevertheless frequently causes significant casualties and damage. The remaining surface area corresponds to the narrow flood zones on either side of the secondary rivers. Specific flood contexts are analysed in detail, including the Shire River-Lake Malawi flood connection, debris flows in mountainous regions, and river mobility in lowland areas. The methodology has been designed to be simple and pragmatic, enabling easy adaptation and application in countries with similar geographical contexts and limited flood hazard knowledge.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105490"},"PeriodicalIF":2.2,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152732","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":"Hybrid turbidite-contourite system on the upper-slope continental margin of the offshore southern Tanzania","authors":"Emily Barnabas Kiswaka ,&nbsp;Dicky Harishidayat ,&nbsp;Oras Joseph Mkinga ,&nbsp;John William Gama","doi":"10.1016/j.jafrearsci.2024.105496","DOIUrl":"10.1016/j.jafrearsci.2024.105496","url":null,"abstract":"<div><div>Cretaceous-Cenozoic hybrid turbidite-contourite (HTCs) systems on the upper-slope region of the northern Rovuma Basin, southern offshore Tanzania have been poorly studied. HTCs have been widely studied from several places due to their petroleum prospectivity, link to geohazards, and potential to help understand deep marine circulation processes and past climates. We have studied 3D seismic data into the northern Rovuma Basin to establish variation and orientation of seismic facies, architectural elements and geomorphologies (based on RMS amplitude maps) characterizing the Cretaceous-Cenozoic HTCs linked to channelized sediment transport and deposition. Two different migration patterns for channelized systems are recognized. They include Cretaceous-Middle Miocene and Middle Miocene-Holocene systems migrating toward SE and NW, respectively. Timing of change in migration trends coincides with change in traverse directions of major submarine channels that allowed sediment transportation by gravity flows. Trajectory of the submarine channels shifted from S-N to SW-NE and approximately W-E during the Middle Miocene, agreeing with the change in channel fills migration trends. The trajectory shift, for the revealed submarine channels was caused by tectonic activity linked to East African Rift System, so does the distribution and migration trends of the HTCs. The study area has hydrocarbon accumulations in the Oligo-Miocene sandstones containing HTCs characterized by a clearly defined depositional system with high RMS amplitudes. The Middle Miocene-Early Pliocene interval has a clear depositional configuration as well, but its low RMS amplitude indicates dominance of fine-grained HTCs with limited reservoir potential. The Late Pliocene-Holocene interval has very high RMS amplitude, but its chaotic configuration implies the presence of poorly sorted sedimentary fills having limited reservoir potential as well. This may be one of the reasons for hydrocarbon discoveries in the study area being limited within the Oligo-Miocene sandstones, and not the younger stratigraphic levels.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105496"},"PeriodicalIF":2.2,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745627","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":"Lithogeochemistry and origin of the komatiites from Mundonguara mine in the Manica greenstone belt, Mozambique","authors":"L.N. Mendes ,&nbsp;O. Martinsson ,&nbsp;D.L. Jamal ,&nbsp;A.M. Azim Zadeh ,&nbsp;C. Wanhainen","doi":"10.1016/j.jafrearsci.2024.105494","DOIUrl":"10.1016/j.jafrearsci.2024.105494","url":null,"abstract":"<div><div>The Manica greenstones belt in western Mozambique constitutes the eastern extension of the Odzi-Mutare greenstone belt in Zimbabwe that is one of several Archean greenstone belts within the Zimbabwe Craton. These greenstones are in Mozambique constituting the Manica Group and are subdivided in two main lithostratigraphic units: The Macequece Formation and the Vengo Formation. The former is hosting the Mundonguara Cu-Au mine and is dominated by volcanic rocks, while the younger Vengo Formation is consisting of epiclastic sedimentary rocks. This paper considers the character and origin of the ultramafic, mafic, and felsic rocks within the Macequece Formation. They include peridotitic komatiite, pyroxenitic komatiite, komatiitic cumulate rocks, gabbroic dykes, rhyolitic units, and a granitic rock intruding the komatiites. Samples of these rocks have been collected from outcrops and drill cores and are investigated through petrographic studies of thin sections and whole rock geochemistry including major and trace elements to interpret the geological environment and tectonic setting.</div><div>The supracrustal rocks are metamorphosed to greenschist facies and the komatiites consists of varying proportions of serpentine, talc, chlorite, and amphibole. Primary features are partly preserved, with spinifex, vesicular, and cumulate textures. The komatiites are variously affected by carbonate alteration and deformation and the rhyolitic rocks are mostly strongly silicified. The komatiites are of the Al-undepleted type, with a MgO content of 25–45 wt %, while the mafic intrusions are tholeiitic in character, varying from gabbronorite to diorite in composition. Trace element diagrams used for interpretation of tectonic setting gives ambiguous results that could be an effect of crustal contamination of the ultramafic and mafic magmas. Using diagrams less sensitive to crustal contamination suggests the mafic and ultramafic magma to have a mantle source Minor rhyolitic rocks are chemically similar to granitic rocks intruding the komatiites and might have a mainly crustal magma source. This suggested that the Manica greenstones belt formed from magmas generated by mantle plume activity in a continental rift setting and were deposited on older Archean continental crust. These rocks are tentatively correlated with the Bends or Brookland formations belonging to the 2.9–2.8 Ga Mtshingwe Group in the Belingwe greenstone belts in Zimbabwe.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105494"},"PeriodicalIF":2.2,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758890","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":"A ∼6,600 year history of vegetation changes and sediment infill of the Moulay Bousselham Lagoon, Atlantic Morocco","authors":"Leroy S.A.G ,&nbsp;Freitas M.C ,&nbsp;Andrade C ,&nbsp;Cearreta A ,&nbsp;Maanan M ,&nbsp;Costa P","doi":"10.1016/j.jafrearsci.2024.105492","DOIUrl":"10.1016/j.jafrearsci.2024.105492","url":null,"abstract":"<div><div>The Moulay Bousselham Lagoon, composed of two parts, Merja Kahla and Merja Zerga, is one of the largest tidal lagoons on the Atlantic coast of NW Africa. Designated as a Ramsar Site, the Moulay Bousselham Lagoon has been identified as a significant carbon sink. Our research aims are to reconstruct regional vegetation changes and lagoonal infill history. The sedimentary infill was studied using three 3–3.5 m long cores dating to the Middle and Late Holocene. The main palaeoenvironmental proxies included sedimentology, foraminiferal analysis and palynology.</div><div>Apart from a basal sandy unit and a later and likely short-lived one, the lagoonal deposits mainly consist of sandy muds with about 10 % organic matter. Our results reveal an environmental transformation from an open lagoon to a restricted one at c. 6600-6100 cal yr BP, coinciding with rising global sea level. While in Merja Zerga grass meadows developed, Merja Kahla, closer to the inlet, was covered by salt marshes. The location of this coastal lagoon remained relatively stable since then, as reshaping is limited by an uplifting barrier consisting of a resistant calcarenite ridge. The Drader River and, since 1953 the Nador Canal, contribute sediment to the lagoon. Sedimentation rates range from 0.01 to 0.09 cm/yr, with a recent ten-fold increase mostly owing to enhanced anthropogenic erosion in the catchments. Despite this, the accommodation space is maintained due to tectonic subsidence along the lagoonal basin and the lower stretch of the river, and the role of carbon sink increases over time.</div><div>The reconstructed vegetation history indicates a decline of the cork oak forest. An ancient human presence is recorded dating back to at least the Neolithic period and suggests the likelihood of ancient <em>Olea</em> usage. This contrasts with much later modifications in vegetation cover in the nearby Rif Mountains.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105492"},"PeriodicalIF":2.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152719","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":"Combined geophysical approach as a tool to identify spatial groundwater aquifer distribution in structurally complex area. Case study of Kasserine aquifer system (central Tunisia)","authors":"Mouez Gouasmia ,&nbsp;Hajer Azaiez ,&nbsp;Ferid Dhahri ,&nbsp;Karim Abidette ,&nbsp;Hakim Gabtni ,&nbsp;Mohamed Soussi","doi":"10.1016/j.jafrearsci.2024.105493","DOIUrl":"10.1016/j.jafrearsci.2024.105493","url":null,"abstract":"<div><div>Many countries are facing water resource scarcity. The Kasserine region in central Tunisia, is characterized with semi-arid climate and it is one of the most affected areas by drought in the country. Groundwater constitutes the main resource for drinking and irrigation water in Kasserine region. The groundwater aquifer levels are very structured, in this geologically complex zone, and their geometry needs to be well characterized. The present study aims to identify the geometry and the distribution of Campanian to Quaternary main aquifers in the Kasserine hydrogeological basin.</div><div>In this study, we adopted a combined geophysical approach; we analyzed and interpreted gravity and seismic existent data in addition to acquiring conventional vertical electrical soundings. The gravity data analysis and mapping revealed that the study area is structured in numerous geological blocks. It highlighted the existence of two major negative gravity anomalies associated with the Megdoudech basin and the Kasserine graben. The gravity maps illustrated the role of the NW-SE Kasserine major Fault in the block structuring. The seismic reflection sections have emphasized the same structuring of the basins. They have exposed the fault network responsible for the compartmentalization of geological structures and which plays an important role in the hydrodynamics of the aquifer system in the region. The geoelectrical investigation highlighted the existence of three aquifer units: the sandy to sandy-clay levels of the Plio-Quaternary in the Kasserine graben, the sandstones of the middle Miocene with an average resistivity of 75 Ω m profiled at different depths, and the Campanian limestones with high resistivities in the Kasserine plateau.</div><div>This combined approach is proven to be very useful to understand groundwater distribution in such geologically complex zones. The results will help the decision makers to ensure the safe management of groundwater resources especially in semi-arid and arid regions.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105493"},"PeriodicalIF":2.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746199","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":"Paleodepositional reconstruction of Lokpanta Shale, Anambra Basin, Nigeria, using organic geochemistry, scanning electron microscopy, and trace elemental analysis","authors":"Gabriel C. Unomah ,&nbsp;Manika Prasad ,&nbsp;Michael A. Oladunjoye ,&nbsp;Idowu A. Olayinka","doi":"10.1016/j.jafrearsci.2024.105491","DOIUrl":"10.1016/j.jafrearsci.2024.105491","url":null,"abstract":"<div><div>The organic-rich Lokpanta shale in the Anambra Basin is considered a potential unconventional hydrocarbon resource in Nigeria. Exploration of unconventional shales requires the paleoenvironmental reconstruction of organic matter productivity and preservation for sweet spot mapping. However, limited studies have been conducted on the paleodepositional factors governing organic matter accumulation in the Lokpanta Shale. This study used scanning electron microscopic and geochemical analyses to reconstruct the paleodepositional settings. Total organic carbon (TOC) content averages 4.34%, indicating very good hydrocarbon generative potential. Lokpanta shale contains Type II organic matter and planktonic foraminifera without benthos, suggesting a marine but limitedly oxygenated setting. The Sr/Ba (1.28–9.27) and Rb/K (37.18–51.93) ratios indicate high paleosalinity, aiding organic matter preservation. Certain enriched trace elements (Mo, Cd, As, Cu, Ti, Ni, and Fe) are similar to signatures in modern hypoxic (e.g., Namibian shelf) and anoxic-euxinic (e.g., Mediterranean sapropels and Black Sea) marine environments, which are both associated with sulfidation for organic matter preservation. Observed pyrite exhibits a primarily spheroidal framboid morphology with an average size of &lt;5.2 μm and a standard deviation of ∼2, indicating a syngenetic origin of an euxinic depositional environment. The paleoredox proxies (Mo/TOC &lt;15 ppm/gTOC, Th/U &gt; 2, V/Sc &gt; 16, V/(V + Ni) &gt; 0.70, and Ni/Co &gt; 6) indicate deposition in highly anoxic and intensely sulfidic waters within a highly restricted sill basin exhibits characteristics of an euxinic setting. In addition, Rb/Sr (0.031–0.132) and Sr/Cu (13.77–28.45) and C-value (&lt;0.1) ratios suggest hot and arid paleoclimate, which aided carbonate productivity. The enrichment of CaO, Si, Ti, Zr, and depletion of Th and rare earth elements (REE) contents suggests low clastic influx aiding in carbonate productivity and organic matter preservation. However, the ratios of Ba/Al (18.5–46.7), Baxs (56.63–489.14), Fe/Ti (4.85–11.29), and Al/Al + Fe (0.58–0.79) suggest that organic matter accumulation was governed by neither primary paleoproductivity nor hydrothermal activities. This euxinic setting may not have extended to coeval shales in other coastal basins of West Africa, even though anoxic conditions existed in those areas.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105491"},"PeriodicalIF":2.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722985","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":"Petrology, geochemistry and REE mineralization of sodalite syenites in the Tijirit gold district, Archean shield of the Reguibat ridge (Mauritania)","authors":"Souadou Taleb Abeydi ,&nbsp;Souad Mrabet ,&nbsp;Marieke Van Lichtervelde ,&nbsp;Ahmedou Mahfoud ,&nbsp;Zein EL. Arby ,&nbsp;El Houssein Abdeina ,&nbsp;Rayane EL. Ghastalany ,&nbsp;Lamia Erraioui ,&nbsp;Mohamed El Mokhtar Dahmada","doi":"10.1016/j.jafrearsci.2024.105476","DOIUrl":"10.1016/j.jafrearsci.2024.105476","url":null,"abstract":"<div><div>The blue sodalite syenites of Tijirit are unusual magmatic rocks, located in the Archean part of the Reguibat ridge within the Ahmeyim greenstone belt in a NS to NNE-SSW trending shear corridor. They form two distinct intrusive bodies, one light-colored and the other dark-oxidized. In view of the lack of previous work, the aim of this project is to specify the main petrological and geochemical characteristics of these particular rocks, and to define their relationship with gold mineralization, with a view to proposing regional prospecting guides. A detailed mineralogical investigation of the syenite silicate assemblages and their mineralizations was undertaken using scanning electron microscopy (SEM), and their major and trace element compositions were analyzed by ICP- AES and ICP- MS. These syenites consist of K-feldspar, albite and sodalite with a secondary assemblage of natrolite and cancrinite. Accessory biotite (annite) is replaced by aegirine and fluorite. Zircon, pyrochlore, Nb-Ta-U-bearing phases and monazite form the mineralized aggregates with fluorite, rare-earth silicates and fluoro-carbonates. The light syenite displays zoned pegmatoid pockets, whereas the dark syenite is characterized by abundant phases of iron and titanium oxides (hematite, ilmenite, Nb-rutile) and carbonates (calcite and Sr-REE carbonates). Tijirit syenites are miaskitic, close to agpaitic, with an average (Na + K)/Al mol.% of 0.96. Our samples reveal high levels of mineralization in REE, Nb and F, with most REE contained in zircon, pyrochlore (Ce-pyrochlore), fluorocarbonates, bastnaesite and monazite, which indicate their affinity to NYF-type magmatism. Geochemical analysis shows OIB-type affinities from a mantle source that generated a Na-enriched residual liquid under fluorine- and chlorine-enriched active fluid conditions for the light-colored syenite and a less evolved term for the oxidized syenite. The blue syenites were emplaced at a deep lineament that allowed the circulation of mixtures of possible mantle fluids responsible for the gold mineralization in the shear corridor of the Ahmeyim greenstone belt.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105476"},"PeriodicalIF":2.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152718","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":"Imaging upper lithospheric structures of the Benue Trough and adjoining basement areas in Nigeria and Cameroon from satellite gravity data","authors":"Goodluck K. Anudu ,&nbsp;Charles O. Ofoegbu ,&nbsp;Stephen E. Obrike ,&nbsp;Obeid S. Lemna","doi":"10.1016/j.jafrearsci.2024.105488","DOIUrl":"10.1016/j.jafrearsci.2024.105488","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study investigates the structures of upper lithosphere in the Benue Trough (BT) and its abutting basements in Nigeria and Cameroon through detailed analyses and interpretation of satellite Bouguer gravity anomaly (BA) data. Matched bandpass filtering, edge enhancements (tilt- and theta-derivatives), 3D inversion, and 2D modelling methods were applied to the BA data. The result from matched bandpass filtering reveals four gravity layer sources with their respective average depths, namely near-surface geological bodies (c. 0.6274 km), depth to basement (sediment thickness; c. 5.8921 km), intra-crustal boundary (c. 12.7538 km) and Moho (c. 27.980 km). Tilt- and theta-derivatives of the BA imaged numerous regional tectonic fabrics/structures exhibiting ENE – WSW, NNE –SSW, and NE – SW major trends coupled with N – S, NW – SE and E − W minor trends across the area, with the major regional tectonic trends mostly dominant in the BT and Adamawa Plateau/Cameroon Volcanic Line (AP/CVL) regions. Positive tilt cum positive theta derivatives of BA indicate that high-density (dense) geological bodies occur within the underlying sediments and crustal basements, particularly within the BT. 3D inversion result reveals a conspicuous and elongated (c. &gt; 600 km long, 120 km wide) NE – SW orientated shallow (c. 23–30 ± 3 km) Moho structure beneath the BT and a prominent elongated, large (c. &gt; 550 km long, 115 km wide) NE – SW striking deep (c. 34–44 ± 3 km) Moho structure below the AP/CVL region in the Western Cameroon Domain/Adamawa-Yade Domain (WCD/AYD) of Cameroon. Also, it shows that the Northern Nigerian Basement Complex (NNBC) and Eastern Nigerian Basement Complex (ENBC) regions are characterised by highly variable Moho morphology and depths (c. 26 to 36 ± 3 km). Generated 3D Moho model represents the first detailed Moho model for this studied area. The result from 2-D forward modelling of a NW – SE representative profile, constrained by known outcrop regional geology and available nearby seismic/teleseismic information, indicates the presence of two variable sedimentary sub-basins (c. 2–5 ± 0.4 km deep), a basement ridge and shallow Moho (c. 23–27 km ± 2 km) in BT region with occurrences of shallow intrusive bodies (e.g. granites), dense lower crustal body and deep Moho (c. 30–40 ± 2 km) underneath the basement regions, particularly in the AYD region. It also highlights that the underlying crust in BT is thinnest while thickest in basement regions of NNBC, ENBC, WCD (particularly AP/CVL area) and AYD along the NW – SE profile. The Moho depth values obtained in this study are within ±3.5 km with all those previously published from teleseismic works in the studied area. The imaged major NE – SW and ENE –WSW orientated tectonic fabrics/structures of the Precambrian crustal basement may have strongly influenced the location, emplacement and orientations of the BT, AP/CVL and Younger Granite complexes. Also, the BT developed in response to mech","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105488"},"PeriodicalIF":2.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723090","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":"Automated lithofacies classification: A comprehensive machine learning approach in Shushan Basin reservoirs, Western Desert, Egypt","authors":"Amr M. Abuzeid ,&nbsp;Ashraf R. Baghdady ,&nbsp;Ahmed A. Kassem","doi":"10.1016/j.jafrearsci.2024.105487","DOIUrl":"10.1016/j.jafrearsci.2024.105487","url":null,"abstract":"<div><div>The application of machine learning serves as a pivotal tool for petroleum geologists in facies classification. This new workflow distinguishes itself from existing classifiers by leveraging hidden statistical patterns in logging data to present a few recognizable clustering options for geologists. These choices are guided by other geological data sources, allowing geologists to retain the dimensional locations of chosen clusters for identification in other wells lacking these additional sources. The classification technique maximizes the value of conventional logging data (gamma ray, resistivity, density, neutron and sonic) for discerning rock typing, porosity ranking, fluid content, highlighting similar petrographic characteristics and elements composition, facilitating the inference of porosity and permeability degrees with high confidence.</div><div>The workflow is designed in this study to predict siltstone, shale, limestone, basaltic intrusions, and coal, accurately identifies various sandstone sub-facies, differentiates between tight and hydrocarbon-bearing sandstone across four wells, with blind validation on a separate well. The classification is validated using Litho Scanner tool, petrography thin sections, and laboratory analysis.</div><div>This comprehensive approach demonstrates the efficiency and applicability of the methodology, marking significant advancements in facies classification within petroleum geology.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105487"},"PeriodicalIF":2.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756736","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":"Seasonal analysis of heavy metaloids concentrations in water and sediments of selective Karu rivers, Nigeria: Ecological implications and risk assessment","authors":"U. Rilwan ,&nbsp;M.I. Sayyed ,&nbsp;M.U. Sarki ,&nbsp;M.K. Raliatu ,&nbsp;A.A. Auwal ,&nbsp;S.A. Nata'la ,&nbsp;M.Y. Hanfi","doi":"10.1016/j.jafrearsci.2024.105485","DOIUrl":"10.1016/j.jafrearsci.2024.105485","url":null,"abstract":"<div><div>There is currently no universally agreed-upon standard for acceptable levels of heavy metals in the surface water and sediment of selected Nigerian rivers. In the study, the concentrations of heavy metals were determined in the surface water and sediments of rivers located in Karu, Nasarawa state, Nigeria. An inductively coupled plasma mass spectrometer was employed to analyze both water and sediment samples. When both seasons are considered, the mean levels of zinc (Zn), copper (Cu), iron (Fe), cadmium (Cd), lead (Pb), and arsenic (As) in water samples from the cold season are approximately two times higher than the mean values in the hot season. The mean values for the cold season were 0.238, 0.278, 0.272, 0.003, 0.075, and 0.082 mg/L for zinc, copper, iron, cadmium, lead, and arsenic, respectively. In sediment samples, the mean concentrations of Zn, Cu, Fe, Cd, Pb, and As in the cold season were 1.72, 0.57, 372.45, 0.80, 0.68, and 14.35 mg/kg, respectively. The geo-accumulation index (Igeo) and the potential ecological risk index (RI) indicated that the contamination levels of the river sediment were low. Nevertheless, a more comprehensive analysis of heavy metals in both water and sediment is required to fully evaluate the health of the ecosystem and effectively manage any potential risks.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105485"},"PeriodicalIF":2.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723089","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}