Journal of African Earth Sciences最新文献

{"title":"New insights from the Choteč Event (early Middle Devonian) in the Marhouma section (Ougarta range, SW Algeria)","authors":"Radia Tandjaoui ,&nbsp;Abdelkader Ouali Mehadji ,&nbsp;Carine Randon ,&nbsp;Houssem Sassi","doi":"10.1016/j.jafrearsci.2024.105486","DOIUrl":"10.1016/j.jafrearsci.2024.105486","url":null,"abstract":"<div><div>The stratigraphic reference section of the Marhouma area (the so-called km 30 section) in the Ougarta Range (North Western Algerian Sahara) provides valuable insights for the Emsian/Eifelian boundary (Lower/Middle Devonian) around the main lithological facies change expressed between the Teferguenite Chefar el Ahmar Formation. This paper presents new data allowing to better constrain and locate regionally the previously established boundary and to locate the Choteč Bioevent. This revision places the boundary below the new record of <em>Icriodus introlevatus</em> Bultynck, 1970 in Bed 3. The ammonoid assemblages place this boundary either at the base of level 25 <em>sensu</em> Göddertz (1987), without excluding placing it a position several meters lower, above the “niveau coralligène of Le Maître (1952)”. The “Choteč” Bioevent is distinguished within a likely polyphase, stepwise local development: i) a facies change well-expressed by a shift from benthic bioclastic packstones to pelagic wackestones (styliolinites); ii) an increasing deepening (thickest marly interval above level 25, Bed 2); iii) the <em>Icriodus introlevatus</em> wackestone Bed 3; iv) a bloom of goniatites (including <em>Pinacites jugleri</em> (Roemer, 1843) and <em>P. eminens</em> Chlupáč and Turek, 1977) in Bed 4, and finally v) a bloom of micromorphic brachiopods in Bed 5, which reflects monospecific mass reproduction due to increased specific trophic levels. This scenario happened in an alternation of marl-limestone layers with a <em>Zoophycus-Chondrites</em> ichnofossil assemblage, interspersed by greenish claystones and calcareous nodule rich in dacryoconarids. The platy shell bed (Bed 5) represented by micromorphic brachiopods represents the peak phase of Choteč Event Interval ranging locally from Bed 4 to Bed 5, and corresponding to Göddertz's level 27.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105486"},"PeriodicalIF":2.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723088","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":"Trace fossil association related to the Upper Miocene transgression cycle in the Lower Chelif Basin, NW Algeria","authors":"Imad Bouchemla ,&nbsp;Madani Benyoucef ,&nbsp;Ahmed Belhadji ,&nbsp;Mohamed Amine Zaidi ,&nbsp;Abdelkader Chachour","doi":"10.1016/j.jafrearsci.2024.105489","DOIUrl":"10.1016/j.jafrearsci.2024.105489","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Tortonian transgression is expressed in the Lower Chelif Basin by the deposition of the Blue Marls Formation highlighted at the base by a deposition of sandstone and conglomerate, including ante-Neogene cobble-size clasts, in which the ichnological investigation shows moderately diversified invertebrate ichnofossils preserved mainly in the detrital-dominated deposits. The trace fossil record consists of 18 ichnospecies belonging to 13 ichnogenera, including &lt;em&gt;Arenicolites carbonaria, Diplocraterion parallelum, Gastrochaenolites&lt;/em&gt; isp., &lt;em&gt;Gyrolithes&lt;/em&gt; isp., &lt;em&gt;Macanopsis&lt;/em&gt; isp., &lt;em&gt;Macaronichnus&lt;/em&gt; cf. &lt;em&gt;segregatis, Ophiomorpha nodosa, Palaeophycus tubularis, Phycodes circinnatum, Phycodes&lt;/em&gt; cf. &lt;em&gt;curvipalmatum, Rhizocorallium&lt;/em&gt; isp., &lt;em&gt;Rosselia socialis, Skolithos annulatus, Skolithos linearis, Skolithos verticalis, Thalassinoides horizontalis, Thalassinoides&lt;/em&gt; cf. &lt;em&gt;suevicus&lt;/em&gt;, and &lt;em&gt;Thalassinoides&lt;/em&gt; isp., produced mostly by deposit-, suspension-, and rarely detritus-feeder organisms. Among these traces, &lt;em&gt;Gastrochaenolites&lt;/em&gt; isp. is the only specimen being recorded within the conglomerate deposits and represents, therefore, the evidence of the first colonization after the Tortonian marine ingression. The remaining trace fossils are exclusively reported from the sandstone deposits and are typical of shallow-marine settings composed of vertical and horizontal structures, largely dominated ethologically by domichnia, fodinichnia, and combined domichnia/fodinichnia behaviour groups. The lower interval of the sandstone deposits is dominated by mid- to deep-tier, vertical post-depositional dwelling (domichnia) forms (&lt;em&gt;Arenicolites, Diplocraterion, Skolithos, Macanopsis, Ophiomorpha,&lt;/em&gt; and &lt;em&gt;Gyrolithes&lt;/em&gt;) attributed to opportunistic suspension-feeding organisms, corresponding to the archetypal &lt;em&gt;Skolithos&lt;/em&gt; ichnofacies that documents an upper-middle shoreface environment, whereas the upper interval is predominantly represented by shallowest- to shallow-tier horizontal deposit-feeders burrows [&lt;em&gt;Macaronichnus, Ophiomorpha&lt;/em&gt; (horizontal components)&lt;em&gt;, Palaeophycus, Phycodes, Rhizocorallium&lt;/em&gt;, &lt;em&gt;Rosselia&lt;/em&gt; (vertical components), and &lt;em&gt;Thalassinoides&lt;/em&gt;] displaying intense degree of bioturbation, reflecting a perfect palaeoecological condition reigning in the water column and sea floor. Thus, the association commonly corresponds to the proximal trend of the &lt;em&gt;Cruziana&lt;/em&gt; ichnofacies developed within the lower shoreface zone. Consequently, the ichnological investigation reveals that the detrital-dominated deposits show a slight deepening of the environment, shifting from a suspension feeder-dominated to a deposit feeder-dominated association, in which polychaete annelid and crustacean animals are the main benthonic epi- and infaunal trace makers of the recorded ichnofossils. The ichnotaxa &lt;em&gt;Arenicolites carbonaria, Phycodes circinnatum, Phycodes&lt;/em&gt; cf. &lt;","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105489"},"PeriodicalIF":2.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745626","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":"Paragenesis and supergene evolution of the Cu-Ba±Pb-Amethyst mineralization from Baba Joua Ali, Eastern Anti-Atlas, Morocco: Exploration application","authors":"Said Courba ,&nbsp;Youssef Hahou ,&nbsp;Jamal Achmani ,&nbsp;Abdelaziz El Basbas ,&nbsp;Abdessalam Ouallali ,&nbsp;Zineb Aafir ,&nbsp;Slimane Sassioui ,&nbsp;Lahcen Ousaid ,&nbsp;Mohamed El Amrani","doi":"10.1016/j.jafrearsci.2024.105466","DOIUrl":"10.1016/j.jafrearsci.2024.105466","url":null,"abstract":"<div><div>The Baba Joua Ali (BJA) ore mineralization is situated in the Maider basin at the Eastern Anti-Atlas. In this area, the mineralization is hosted within the Ktaoua group and the Second Bani Formation of the Upper Ordovician. The upper Ordovician terrane display ductile deformation, characterized by a succession of synclinal and anticlinal structures. From north to south, the Ordovician formations show a WNW-ESE trend syncline at Jbel El Machhot. The veins ore mineralization is controlled by N-S to NE-SW trending faults. These faults are linked to the Variscan orogeny and kinematic indicators suggesting left-lateral and right-lateral motions, respectively. Based on the metallographic relationship between minerals from outcrop to microscopic observation, two major mineralizing stages are proposed for the precipitation of ore mineralization. The first is a hypogene stage with a banded texture, it comprises colorless quartz with sulfides, amethyst with iron oxide, and finally barite and sulfides. Microthermometric analysis of fluid inclusions was carried out on colorless quartz and amethyst. Primary fluid inclusions trapped in colorless quartz indicate temperatures from 120 to 140 °C and salinity between 14.46 and 19.84 wt% NaCl eq. This fluid is characterized by Te ranging from −32 to −22 °C, interpreted as a NaCl-H₂O system. The fluid inclusion from amethyst indicates a temperature from 100 °C to 110 °C and salinity between 13 and 14 wt% NaCl eq. The banded texture of the primary mineralization (border to center: colorless quartz, amethyst, and barite) reflects the extension context and may correspond to fluid percolation in the Variscan orogeny fault during the Triassic extension (CAMP). The second major stage is characterized by the formation of covellite, chalcocite, malachite, hematite, chrysocolla, cuprite and native copper. This assemblage is linked to the supergene process, the percolation of meteoric acidic water is favored by the intense fracturing in upper Ordovician quartzite, cavities, and fractures crosscutting quartz, amethyst, and barite. The copper and iron oxide with copper carbonate observed at BJA correspond to oxidized zone.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105466"},"PeriodicalIF":2.2,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143152720","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":"A novel approach for integrating spatial data in gold prospectivity mapping using a modified TODIM method, a case study: Basiran-Mokhtaran - Eastern Iran","authors":"Hosein Ferdowsi,&nbsp;Abbas Bahroudi,&nbsp;Ali Moradzadeh,&nbsp;Maysam Abedi","doi":"10.1016/j.jafrearsci.2024.105482","DOIUrl":"10.1016/j.jafrearsci.2024.105482","url":null,"abstract":"<div><div>To address the significant challenges posed by varying methodologies across diverse environments, it is imperative to enhance innovative approaches for Mineral Prospectivity Mapping (MPM). A significant issue arises in greenfield regions, where determining the appropriate weights for various geospatial layers in MPM leads to a considerable difficulty. Given the scarcity of known deposits of similar types in these areas, relying on experienced geologists for layer weighting often results in biased outcomes that reflect the subjective views of the experts. This study utilized available geological, airborne geophysical, geochemical, and remote sensing datasets to develop reliable evidence layers for gold exploration, despite the fact that much of the study area is covered by alluvial deposits and has only a few known occurrences of gold and copper. The prediction-area (P-A) method was used to assess the weight of each geospatial layer, independent of the geologist's subjective evaluations. This data-driven approach quantifies the significance of each layer by analyzing the ratio of known deposits to their respective areas. Ultimately, these calculated weights were utilized to create a gold prospectivity map for the region through a modified TODIM and multi-index overlay (MIO) method. The TODIM method, a sophisticated pairwise comparison technique that accommodates preferences for either profit or loss, was refined through subtle adjustments to its calculation algorithm, enhancing its efficiency in managing a multitude of alternatives. In our approach, we employ a classification procedure rather than a ranking system to determine the final outputs of TODIM. To assess the efficacy of the modified TODIM, we utilized the index overlay method as a benchmark for performance evaluation.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105482"},"PeriodicalIF":2.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745628","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":"Paleoenvironmental and sea level changes across the Paleocene-lower Eocene interval at the central and southwestern Sinai, Egypt","authors":"Azza A. Mohamed ,&nbsp;Nageh A. Obaidalla ,&nbsp;Abdelhamid M. Salman ,&nbsp;Kamel H. Mahfouz ,&nbsp;Amr A. Metwally","doi":"10.1016/j.jafrearsci.2024.105483","DOIUrl":"10.1016/j.jafrearsci.2024.105483","url":null,"abstract":"<div><div>Detailed stratigraphic studies of the Paleocene-lower Eocene interval were conducted on four stratigraphic successions (Sudr-Alhitan, Thamad, Abu-Qada, and Nukhul) in central and southwestern Sinai. These sections are arranged along a North-South direction as: Sudr-Alhitan, Thamad, Abu-Qada, and Nukhul. The biostratigraphic framework was achieved by integrating data of calcareous nannofossils and planktonic foraminifera. The studied area experienced two major tectonic events, most likely related to the Syrian Arc System (SAS), which led to two distinct hiatuses of significant magnitude, evidenced from integrated biostratigraphic analysis and thorough field observations. Benthic foraminifera assemblages suggest a deposition in outer neritic to upper bathyal setting for investigated sites, except for the Tarawan and Thebes formations in Abu-Qada and Sudr-Alhitan sections, which were deposited in middle-outer neritic and outer neritic settings, respectively. Benthic foraminiferal indices indicate an oligo-mesotrophic environment associated with oxic/suboxic conditions at the bottom of the seawater for the studied interval. Low oxygen levels and mesotrophic conditions were seen to mark the Paleocene Eocene Thermal Maximum event, as evidenced by the organic-rich laminated sediment, low benthic foraminiferal indices, and the occurrence of agglutinated taxa <em>Repmanina charoides</em> and <em>Ammobaculites</em> spp., which reflects a major change in food supply. The obtained sequence stratigraphic framework shows that the depositional record of the studied area is significantly influenced by both the regional tectonics and eustatic sea level.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105483"},"PeriodicalIF":2.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723087","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 and geochemistry of the Suhum Basin granitoid complex, Ghana: Implications for crustal growth during the Rhyacian orogeny of the West African Craton","authors":"Daniel Kwayisi ,&nbsp;Prince Ofori Amponsah ,&nbsp;Emmanuel Kwaku Awunyo ,&nbsp;Marian Selorm Sapah ,&nbsp;Patrick Asamoah Sakyi ,&nbsp;Ben-Xun Su ,&nbsp;Prosper M. Nude ,&nbsp;Abigail Enyonam Ayikwei ,&nbsp;Eric Dominic Forson","doi":"10.1016/j.jafrearsci.2024.105475","DOIUrl":"10.1016/j.jafrearsci.2024.105475","url":null,"abstract":"<div><div>The Suhum Basin granitoid complex is an important granitoid complex of the Birimian terrane of Ghana for unravelling the crustal growth and evolution of the West African Craton (WAC) during the Rhyacian Eburnean orogeny. Almost the entire Suhum Basin is occupied by an extensive granitoid complex, which contains useful information for constraining debatable plate tectonic issues, especially during the Archean-Paleoproterozoic transition period. We present petrography, whole-rock geochemistry, and mineral chemistry data of biotite, amphibole, and plagioclase to constrain the temperature-pressure conditions of emplacement, petrogenesis, tectonic setting, the evolution of the granitoids complex of the Suhum Basin, and its implications for the crustal growth and evolution of the WAC. Four lithological types; granite gneiss, migmatites, leucogranites, and mafic enclaves, characterise the granitoid complex of the Suhum Basin. Biotites from the granitoid complex have an annite-siderophyllite composition, and that, coupled with their calc-alkaline and I-type signatures, indicates crystallisation of the granitoid complex of the Suhum Basin under oxidised conditions. The medium-to high-K character of the rocks, together with the calc-alkaline nature, may be a reflection of the generation of magma in regions where the mantle wedge might have interacted with enriched fluids from the underlying plate during dehydration. The enrichment of LILE and LREE relative to HREE and HFSE and the negative Eu, Nb-Ta, and Ti anomalies of the granitoids complex may indicate derivation from enriched magma sources with varying degrees of fractionation in an arc environment. Amphibole-plagioclase thermobarometry indicates that the granitoid complex formed at P-T conditions of 600–712 °C and 5.2–7.2 kbar, signifying a deeper depth (19–27 km) of emplacement. The overall geochemical data suggest that the rocks formed during a single orogenic event related to a volcanic arc environment where subduction zone components played a role in the generation of their parental magmas. This finding is therefore consistent with the onset of “modern-style” subduction-related processes during the Archean-Paleoproterozoic transitional period.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"222 ","pages":"Article 105475"},"PeriodicalIF":2.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723086","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":"Spatio-temporal land use/land cover change analysis and assessment of urban heat island in Ghana: A focus on the Greater Accra Region","authors":"Abraham Aidoo Borsah ,&nbsp;Evans Annan Boah ,&nbsp;Eric Thompson Brantson","doi":"10.1016/j.jafrearsci.2024.105474","DOIUrl":"10.1016/j.jafrearsci.2024.105474","url":null,"abstract":"<div><div>The expansion of cities coupled with economic development over the years has transformed many locations into hotspots for massive urban populace. The Greater Accra Region which is the capital city of Ghana is no exception. The urban population growth rate in the region has expanded extensively at the expense of increasingly vegetation cover. As a result, there is an increasing need to investigate urban resilience, land use/land cover (LULC) change, and urban heat islands (UHI) dynamics in the region. The aim of this study is to analyze multi-spectral Landsat images of 2000 and 2020 to examine the LULC change and the UHI trend across the Greater Accra Region of Ghana. The results from the analysis show a significant change in the spatial trend of land surface temperature (LST) and UHI between the years 2000 and 2020. Spatial distribution of LST from 0 °C to 28 °C and 17 °C–33 °C in the years 2000 and 2020 respectively were observed. Urban areas dominated more than half of the study area in 2020, covering 85% (equivalent to 3160 sq. km), and reflecting a 20% increase from the year 2000–2020. During the same period, sparse and dense forested areas decreased by 10% (373 sq. km) and 4% (146 sq. km) with a 5% reduction in bare land (equivalent to 177 sq. km). The spatio-temporal analysis revealed a significant surge in the population of urban areas within the study area. The UHI areas also increased from 13.20% in 2000 to 18.20% in 2020. On the other hand, non-UHI areas decreased from 86.80% to 81.80% during the same period. The successful contribution of this research demonstrates the usefulness of spatial models as tools in generating LULC maps for assessing UHI to facilitate future sustainable city planning.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"221 ","pages":"Article 105474"},"PeriodicalIF":2.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651973","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":"Using archive hydrogeological data to enhance the hydrodynamic knowledge of hardrock aquifers in Western Africa","authors":"Mozimwè Ani ,&nbsp;Jessy Jaunat ,&nbsp;Béatrice Marin ,&nbsp;Frederic Huneau ,&nbsp;Kissao Gnandi","doi":"10.1016/j.jafrearsci.2024.105477","DOIUrl":"10.1016/j.jafrearsci.2024.105477","url":null,"abstract":"<div><div>In the Kara River Watershed (KRW, northern Togo), drinking water is mainly supplied by groundwater flowing through fissures in the metamorphic formations of the Dahomeyides belt. The study was based on the use and valorisation of hydrogeological archive dataset from 1970s to 2021. The database comprises 1389 boreholes, but only 710 are considered after pre-treatment, and provides information mainly on total depth, weathering thickness, discharge at drilling, piezometric level, specific discharge, transmissivity, and the nature of the lithology tapped. The methodological approach involved statistical analysis of data, characterization of the fissured horizon, establishment of relationships between hydrodynamic parameters and satellite image processing. The results showed that the aquifers structure is close to those observed worldwide in hardrock context and they provide operational details on the hydrogeological functioning of these environments in the West African particular context. From the surface downwards, aquifers show a layer of saprolite (thickness between 0.2 and 37.3 m) acting as a storage level, a fissured layer whose permeability depends on the number and connectivity of the fissures, and then a level of very low permeability, unfissured bedrock. In the study area, the depth of the useful fissured medium is 52 m with an average useful discharge of 7.1 m³ h⁻¹. The coefficients of variation for specific discharge and transmissivity are greater than 100%, reflecting the structural heterogeneity of the study area. Analysis of the discharges measured in the boreholes as a function of lithology shows that the metasediments are more productive than other geological formations. Finally, all the geological, hydrogeological, and hydrodynamical data have been used to propose a preliminary conceptual model of the watershed's hardrock aquifers. These results will serve as decision-making tools for water managers and will facilitate the policy of integrated management of groundwater resources at the scale of the KRW. The developed methodology also shows how archive data should be used to achieve optimized management of aquifers without major investments.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"221 ","pages":"Article 105477"},"PeriodicalIF":2.2,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651974","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":"Analyzing seismic impact across regions: A comprehensive study of the Pazarcık and Elbistan earthquakes in Türkiye (February 6, 2023)","authors":"Özgür Yıldız ,&nbsp;Ali Fırat Çabalar","doi":"10.1016/j.jafrearsci.2024.105463","DOIUrl":"10.1016/j.jafrearsci.2024.105463","url":null,"abstract":"<div><div>The seismic events in Pazarcık (Mw 7.7) and Elbistan (Mw 7.6) on February 6, 2023, caused widespread damage and destruction across 11 provinces and districts in eastern Türkiye. Despite similarities in construction quality and structural stock characteristics, notable differences in the patterns of destruction between the affected cities have highlighted the need for a more detailed investigation. This study focuses on examining local site effects and seismic behavior in residential areas within the impacted zone to better understand the structural damage caused by these earthquakes. Geotechnical data from the affected cities were used as the basis for conducting nonlinear seismic site response analyses. These analyses, using real earthquake records measured in city centers, explored factors such as liquefaction potential, amplification capacity, and the dynamic behavior of soil profiles under seismic loads. Simulations based on actual earthquake records and soil data provided insights into the causes of structural damage in the affected areas during both seismic events. Finally, an evaluation of site effects on structural damage resulting from both major earthquakes was conducted, offering valuable insights through a comprehensive analysis of the results.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"223 ","pages":"Article 105463"},"PeriodicalIF":2.2,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759002","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 and geochemistry of volcanic rocks of the Kulf-Amba area, in the Northwestern Ethiopian plateau: Implication for petrogenesis of felsic volcanic suites","authors":"Dejen Teka ,&nbsp;Minyahl Teferi Desta","doi":"10.1016/j.jafrearsci.2024.105465","DOIUrl":"10.1016/j.jafrearsci.2024.105465","url":null,"abstract":"<div><div>The Kulf-Amba area, located on the Northwestern Ethiopian plateau, is primarily composed of Cenozoic volcanic rocks with minor intertrappean sediments. To understand the petrogenesis of these rocks, we conducted field investigations, petrographic studies, and geochemical analyses. The main volcanic products include basalt (upper and lower), rhyolite lava flows, rhyolitic ignimbrite, volcanic glass, and agglomeratic tuff. Basalts exhibit aphanitic, porphyritic, and glomerophyric textures, with phenocryst of olivine, Ca-rich plagioclase, clinopyroxene, and Fe-Ti oxides. Felsic rocks display porphyritic, aphyric, and glassy textures, with phenocryst of quartz, alkali feldspar, and Fe-Ti oxides. Geochemical data reveal a bimodal composition. The mafic rocks resemble high titaniferous (HT2) basalts of Northwestern Ethiopia and are classified as transitional to tholeiitic. Felsic rocks are primarily peralkaline comendites. The mafic rocks exhibit a depleted heavy rare earth element (HREE) pattern with (Dy/Yb)_N = 1.75–2.02 and enriched light rare earth element (LREE) values with (Ce/Yb)_N = 7.16–9.26, without a significant negative Eu anomaly. Enrichment in LREE with (Ce/Yb)_N = 6.27–15.03 and flat HREE with (Dy/Yb)_N = 1.23–1.79, with varying Eu negative anomaly are characteristics of the felsic volcanic rocks, indicating removal of plagioclase throughout their evolutionary process. The consistent Nb/Ta (17.29–23.67 ppm) and Zr/Hf (37.53–45.08 ppm) ratios in both mafic and felsic rocks suggest that fractional crystallization was the dominant process in their formation, with small crystal contamination. The primitive mantle-normalized variation diagram for the mafic rocks reveals LREE enrichment and HREE depletion, indicating garnet in the source. Melting models using primitive mantle normalized values of Sm/Yb vs. La/Sm ratios further confirm garnet's presence and suggest a low degree (2%) of partial melting a source with less than 2% of garnet. The trace element signatures and geochemical modelling of the mafic lavas indicate a plume-related origin, potentially related to the Afar mantle plume.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"221 ","pages":"Article 105465"},"PeriodicalIF":2.2,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651409","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}