Journal of African Earth Sciences最新文献

{"title":"Petroleum accumulation and distribution mechanisms in the Sirt Basin, central-north of Libya","authors":"Khaled Albriki ,&nbsp;Wei GuoQi ,&nbsp;Wen Zhixin ,&nbsp;Feiyu Wang ,&nbsp;Rajab El Zaroug","doi":"10.1016/j.jafrearsci.2026.105994","DOIUrl":"10.1016/j.jafrearsci.2026.105994","url":null,"abstract":"<div><div>The current study aims to understand the light petroleum phase distribution across 320 discovered fields within 147 blocks (onshore/offshore). Integrated basin data, including regional geology and organic geochemistry from over 7400 wells were used. Key major geological and geochemical elements, including reservoirs, source rocks, seal presence and characteristics, and petroleum generation and accumulation scenarios, were examined. The basin hosts an excellent reservoir system that varies from carbonates, clastic, and fractured basement. Reservoirs in the Sirt Basin generally ranges in age from Mesozoic to Cenozoic, with a burial depth ranging from 1600 to 2700 m. The basin contains high-quality to mature (postmature stage) Triassic, Cretaceous, and Paleocene source rocks, including from older to younger, the Mid Nubian shale, Etel, Rachmat, Sirte shale, Kalash, and Hagfa shale formations. These source rocks, which have marine, lacustrine, and terrestrial origins, are dominated by type B, C, and D/E organofacies that significantly influence the petroleum charge phase type and amount. The basin source rocks exhibit excellent potential for petroleum generation, with present-day average total organic carbon (TOC) values up to 4 % and average hydrogen index (HI) values up to 650 mg HC/g TOC with regionally defined moderate to high levels of transformation and expulsion efficiency (&gt;60 %). High-capacity sealing system composed primarily of thick shale and anhydrite lithofacies. These robust basin seals, combined with a densely faulted geological environment, create an excellent geological system for trapping the Meso-Cenozoic petroleum phase (oil and gas). Regional charge and accumulation scenario characterized by shallow (western and eastern troughs) to deep (central north) light-phase petroleum generation from various locations, followed by a successful early to late entrapment process. The distribution of the petroleum charge phase within the basin is structurally controlled by the presence of thick Cenozoic carbonate buildups, both onshore and offshore of the Sirt Basin. With the significant exploration and development activities, there remains promising petroleum potential for future opportunities in the Sirt Basin, particularly in deep onshore troughs (where light oil is the dominant phase) and deep to ultra-deep offshore plays (dominated by thermogenic gas phase).</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 105994"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940735","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":"Diamond indicator minerals: The case of the Séguéla diamondiferous provinces, West-central Côte d'Ivoire, Southern part of the West African Craton","authors":"Ziandjêdé Hervé Siagné ,&nbsp;Koffi Alexis N'dri ,&nbsp;Kouadio David Koffi ,&nbsp;Miryam Tessia ,&nbsp;Marc Ephrem Allialy ,&nbsp;Yacouba Coulibaly","doi":"10.1016/j.jafrearsci.2026.106015","DOIUrl":"10.1016/j.jafrearsci.2026.106015","url":null,"abstract":"<div><div>The research carried out in the Séguéla diamondiferous district in West-central Côte d'Ivoire (Paleoproterozoic domain) has led to the discovery and artisanal exploitation of diamonds. The area is characterized by kimberlite to lamproite dykes and pipes, as well as alluvium and colluvium in which diamonds are found. However, these formations (kimberlite and lamproite dykes) are covered by sedimentary deposits, which prevent them from outcropping. Therefore, the only indicators that can be linked to them are their weathering minerals. This study aims to identify minerals that could be diamond indicators. Three distinct types of concentrates of alluvium, colluvium and kimberlite concentrates are used to test this. The mineralogical study of these concentrates under a binocular microscope revealed diamond, as well as a high proportion ilmenite, olivine and chromite. The chemical analysis revealed the presence of magnesian ilmenites in the Séguéla concentrates, which would be derived from kimberlite (either Toubabouko or Bobi). In addition, kimberlitic activity in the Séguéla region suggests a possible link with that observed in the West African Craton (Sierra-Leone, Liberia, and Guinea). Finally, despite the absence of pyrope garnet in the concentrates, the following minerals: ilmenite (Mg-Ilmenite), olivine and chromite may serve as diamond indicators for deposits in the Séguéla region.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106015"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940738","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":"Diagenesis and hydraulic flow characteristics of the Paleozoic Shifa sandstones in the western desert, Egypt: Implications for new prospective reservoir targets","authors":"Ahmed Ismail Mahmoud ,&nbsp;Xiaodong Ma ,&nbsp;Shib Sankar Ganguli ,&nbsp;Ahmed Shakkar ,&nbsp;Ahmed M. Metwally ,&nbsp;Walid M. Mabrouk ,&nbsp;Mahmoud Leila","doi":"10.1016/j.jafrearsci.2026.106040","DOIUrl":"10.1016/j.jafrearsci.2026.106040","url":null,"abstract":"<div><div>The Paleozoic reservoirs of Shifa Formation sandstones in Egypt's Western Desert are deeply buried (&gt;3500 m) and poorly explored, with significant uncertainties concerning the controls of depositional and diagenetic attributes on their hydraulic flow properties. In this regard, we integrate geophysical, petrographical, petrophysical and machine learning results to investigate spatiotemporal evolution of different reservoir rock types (RRTs) and hydraulic flow zones. We found that eodiagenetic infiltration of clays, kaolinite cementation, and mesogenetic quartz overgrowth are the key burial modifications controlling the evolution of the pore network of the Shifa sandstones. Two sandstone microfacies were reported: quartz arenite and kaolinitic quartz arenite. Petrographic analysis demonstrates that early diagenesis significantly degraded the reservoir quality of the kaolinite-rich sandstones, while mesodiagenesis has a mild impact on the sandstones' pore system. Lithofacies analysis reveals that the lower part of the Shifa succession consists mainly of mudstones and kaolinitic quartz arenites, which exhibit lower porosity and permeability compared to quartz arenite sandstones. The stratigraphic modified Lorenz plot (SMLP) and 3D property models demonstrate that the spatial distribution of quartz arenite sandstones predominantly controls fluid flow conduits. Bayesian neural network (BNN) models demonstrated their effectiveness in estimating the permeability of the Shifa sandstones microfacies, thereby improving the predictability of the best RRTs. These findings showcase the promising potential of BNN and integrated reservoir characterization analyses for developing reliable hydrocarbon exploration strategies in the region, thereby offering economic benefits.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106040"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146090711","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":"Petrological and geochemical characteristics of the Skouraz banded iron formation in the Bou Azzer inlier, central Anti-Atlas, Morocco: Insights into geodynamic implications","authors":"Amina Wafik ,&nbsp;Mohamed Ben massoude ,&nbsp;Nahla Ntarmouchant ,&nbsp;Hassan Admou ,&nbsp;Reda Chatiby ,&nbsp;Youssef Atif ,&nbsp;Amin Beiranvand Pour","doi":"10.1016/j.jafrearsci.2026.106006","DOIUrl":"10.1016/j.jafrearsci.2026.106006","url":null,"abstract":"<div><div>Banded Iron Formations (BIFs) were previously unrecognized within the Pan-African Anti-Atlas orogenic belt in Morocco. Detailed investigations of quartz-ferruginous formations within the Skouraz volcano-sedimentary complex, Central Anti-Atlas, have led to the reclassification of these iron-rich deposits from Oligistschist to BIFs. The study involved geological mapping, petrological and mineralogical analyses (SEM, ICP-AES, EPMA), confirming the characteristic banded structure and mineralogy typical of BIFs. Geochemical data reveal high SiO₂, Fe₂O₃, and Ba contents consistent with Neoproterozoic BIFs, particularly of the Rapitan type, with a minimum Fe content of 15 %. These BIFs are hosted in the Skouraz metasedimentary clastic-carbonate complex, which experienced greenschist facies metamorphism and formed through hydrogenous and hydrothermal processes during the second magmatic event of the Assif n'Bougamane-Takroumt complex (760–700 Ma). Originating from Fe-shale and Fe-sand protoliths during a Cryogenian glaciation event, these formations are estimated to date from the late Lower Cryogenian to the early Upper Cryogenian, providing a rare and detailed record of Precambrian glacial and ocean redox conditions. The Skouraz area features thick glacial diamictites layered with BIFs, reflecting climatic fluctuations and hydrothermal influences. This study enhances understanding of Neoproterozoic iron formation and highlights the role of glaciation and tectonics in BIF genesis.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106006"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940736","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":"Sedimentary facies and reservoir evolution of the Cretaceous Alamein Formation, Alamein Basin, northern Western Desert, Egypt","authors":"Zixuan Liu,&nbsp;Hong Zhang,&nbsp;Yongjie Hu","doi":"10.1016/j.jafrearsci.2026.106020","DOIUrl":"10.1016/j.jafrearsci.2026.106020","url":null,"abstract":"<div><div>The Lower Cretaceous Alamein Formation in the northern Western Desert, Egypt, host significant petroleum reserves. Petrographic observation, porosity-permeability analysis and logging-seismic interpretation were performed here using core samples, well log data, and 3D seismic datasets to discuss the sedimentary facies and reservoir evolutions of the Alamein Formation. Sedimentary facies of the Alamein Formation in the Alamein Basin consists of inner ramp, shallow ramp, and outer ramp–deep basin facies. Compared with other carbonate facies, dolo-grainstone, dolo-floatstone, and dolo-rudstone display superior reservoir quality. Most host dolostone experience near-surface evaporation-reflux dolomitization, indicated by three types of anhydrites. Zebra dolostone and saddle dolomite are typical precipitates of deep-burial hydrothermal dolomitization. Reservoir space consists of stratiform dissolution pores, vugs, moldic pores, inter- and intra-crystalline dissolution pores, and fractures. High-energy depositional environment is the foundation of the potential reservoirs, and thus dolo-grainstone, dolo-floatstone, and dolo-rudstone yield higher porosity and permeability than other types of lithofacies. Marine regression-transgression results in better reservoir performance in the top intervals compared to dolostone at the base section within meter-scale cycles. Reservoir performance is further enhanced by meteoric leaching, evaporation and reflux dolomitization through early burial stages. During the intermediate burial regimes, hydrothermal alteration and thermochemical sulfate reduction generate secondary pores, including (i) intra-crystalline dissolution pores within coarse-crystalline dolomite and saddle dolomite, and (ii) vugs developing along stylolites. Moreover, tectonic activities contribute to the development of fracture networks, which significantly enhance fluid flow. Different types of sedimentary facies, complex diagenetic history and tectonic activities result in the different reservoir performance of the Alamein Formation and other carbonate formations in the northern Western Desert. These findings underscore the hydrocarbon potential of reefal and shoal dolostone reservoirs in Lower Cretaceous carbonates worldwide, providing important implications for hydrocarbon exploration.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"236 ","pages":"Article 106020"},"PeriodicalIF":2.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034964","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":"Erratum to “Mesozoic Pb-Zn hydrothermal veins in the Jebilet, Morocco: Constraints from mineralogy, fluid inclusions and stable isotope data” [J. Afr. Earth Sci. 234 (2026) 105940]","authors":"Samira Essarraj ,&nbsp;Félix Nshimiyimana ,&nbsp;Mohamed Hibti ,&nbsp;Philippe Boulvais ,&nbsp;Michel Cathelineau","doi":"10.1016/j.jafrearsci.2025.105987","DOIUrl":"10.1016/j.jafrearsci.2025.105987","url":null,"abstract":"","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105987"},"PeriodicalIF":2.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921768","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":"Trend analysis of climate-driven changes in river discharge in Nigeria's benue river basin","authors":"John Ayuba Godwin ,&nbsp;Shruti Singh ,&nbsp;Ishaku Joshua Dibal ,&nbsp;Rajesh Kumar","doi":"10.1016/j.jafrearsci.2025.105967","DOIUrl":"10.1016/j.jafrearsci.2025.105967","url":null,"abstract":"<div><div>Understanding the influence of climate variability and land use change on hydrological regimes is essential for sustainable water resource management, particularly in vulnerable regions like Nigeria's Benue River Basin. This study analyzes long-term trends from 1990 to 2023 in hydro-climatic variables and land use/land cover (LUCC) dynamics to assess combined climate and human impacts on river discharge. We employed non-parametric Mann-Kendall tests, Sen's slope estimators, and cumulative Mann-Kendall methods to detect trends in precipitation, temperature, discharge, and water levels. LUCC changes were quantified using Landsat imagery for 1990, 2000, 2010, and 2020, validated by high-resolution Google Earth imagery and ground observations. Results indicate significant basin-wide warming (Tmax: +2.1 ± 0.3 °C), increased rainfall variability, and reduced discharge (−0.18 ± 0.05 units/year). Pearson's correlation coefficients confirmed strong linear agreement between observed and modeled hydro-climatic variables (annual discharge r = 0.97, p &lt; 0.001; precipitation r = 0.99, p &lt; 0.001; Fig. 5), substantiating trend robustness. LUCC analysis reveals a 21.4 % decline in forest cover alongside 29.7 % and 38 % expansions in cropland and urban areas, respectively. Regression modeling shows climate variables explain approximately 29.2 % of discharge variability, and LUCC factors about 21.5 %, jointly accounting for over 50 % of total variation (R² = 0.51, p &lt; 0.01). Urbanization strongly correlates with peak flow extremes, while forest loss reduces base flow and infiltration. These findings demonstrate that hydrological changes in the Benue Basin result from interacting climatic and anthropogenic drivers. Adopting combined climate-human adaptive strategies, including reforestation, green urban infrastructure, and land use regulation, will improve hydrological resilience amid escalating environmental changes.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105967"},"PeriodicalIF":2.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836991","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":"Impact of paleotopography on carbonate reservoir heterogeneity in the Kangan Formation: A comparative research in the central and Western Persian Gulf using the Winland method","authors":"Sogand Asadolahi Shad,&nbsp;Sepideh Davoodi,&nbsp;Vahid Tavakoli","doi":"10.1016/j.jafrearsci.2025.105977","DOIUrl":"10.1016/j.jafrearsci.2025.105977","url":null,"abstract":"<div><div>Understanding the controls on depositional and diagenetic heterogeneity is essential for predicting reservoir quality in carbonate systems, particularly in structurally complex settings. Structural features such as paleohighs strongly influence sediment distribution, diagenetic pathways, and the evolution of pore systems. However, their influence on reservoir quality has not been fully evaluated using an integrated quantitative approach. This study examines how paleohighs affect the depositional and diagenetic characteristics of the Kangan Formation carbonates using the Winland method at both micro- and macro-scales. Two wells in the Persian Gulf have been compared; one located in the central region within the S1 Field (Well A) and the other in the western region within the S2 Field (Well B). A dataset including 1159 thin sections, 989 porosity and permeability measurements, and 75 mercury injection capillary pressure analyses was employed to establish relationships between porosity, permeability, and pore-throat size distributions. In total, 10 microfacies were identified in S1 and 12 in S2, representing deposition across five carbonate sub-environments. The shallow depositional setting on the Qatar Arch paleohigh increased the influence of meteoric diagenesis and dolomitization in S1, resulting in larger pore-throat diameters. In contrast, anhydrite cementation in the S2 occluded pore-throats. Although the two fields share similar depositional conditions, differences in diagenetic intensity produced distinct reservoir characteristics. These results confirm that paleogeographic and morphological factors have had a profound effect on both depositional architecture and diagenetic modification. Application of the Winland method provided the quantitative data needed to clarify these relationships. Based on the Winland method, seven rock types were identified in S1 and eight in S2. These classifications reflect the variability in pore-throat sizes and help distinguish subtle differences in reservoir quality between the two fields. This integrated approach provides new insight into carbonate reservoir evolution and contributes to more reliable reservoir characterization for exploration and development.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105977"},"PeriodicalIF":2.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837066","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":"Analysis of the active tectonics of the Aşkale-Pasinler-Horasan Basins (Eastern Anatolia) using multichannel seismic reflection and stratigraphic data","authors":"Yakup Abdik ,&nbsp;Neslihan Ocakoğlu ,&nbsp;Bülent Kaypak","doi":"10.1016/j.jafrearsci.2025.105950","DOIUrl":"10.1016/j.jafrearsci.2025.105950","url":null,"abstract":"<div><div>Stratigraphic and structural features of the Aşkale-Pasinler-Horasan basins located within the borders of Erzurum Province in the Eastern Anatolia Region were investigated to depths of approximately 3–4 km by evaluating 1300 km of multichannel 2D seismic reflection data and three boreholes collected in the region between 1977 and 2001. A total of eight seismic units ranging from Mesozoic to Plio-Quaternary were interpreted within the basins. Seismic stratigraphy and structural features show that Aşkale, Erzurum, Pasinler and Horasan basins were initiated and began to shape during the tectonic regime extending from the Mesozoic to the Late Miocene, with possible strong compression, rapid uplift and long-term erosion processes, respectively. Particularly, Mesozoic Ophiolites play an important role to form these basins and ridges geometry at present. Because both the ophiolites are widespread under the Neogene deposits of basins and the wells drilled in this region penetrate into the ophiolitic melange by cutting through the Neogene deposits. The Late Miocene erosional surface is overlain by very gently accumulated horizontal sediments deposited from the Upper Miocene to present within the basins (∼2.0 km thick). These interpretations on the seismic sections indicated that compressional tectonic regime has remarkably left the region after Late Miocene. However, within the Plio-Quaternary sediment strata, several active N-S to NE-SW oriented strike-slip faults with reverse components, WNW-ESE oriented strike-slip faults and ENE-WSW oriented positive flower structures were mapped. These faults are interpreted as Plio Quaternary in age, which are responsible for the recent deformation in the basins and their surrounding region. The major of them either overlap with the previously mapped active Aşkale, Erzurum and Pasinler fault zones in the region or form their continuations within the basin. These compressional strike-slip faults border the basins and elevate the ridges to the north and to the south. Thus, they form ramp basins structures in the Aşkale, Pasinler and Horasan. In addition, newly mapped strike-slip faults and positive flower structures squeeezed the basin deposits within the Aşkale, Erzurum and Horasan basins. It is seen that the basins and ridges have recently been under a compressional strike-slip tectonics. The quantitative analysis of earthquake focal mechanisms supports our fault orientation and character. It reveals an approximately NNE-SSW maximum horizontal stress (SHmax) orientation within these basins which is primarily controlled by the continental collision between the Arabian and Eurasian plates.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105950"},"PeriodicalIF":2.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735047","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":"Mineralogical and geochemical characterization of the Wigu Hill Carbonatite dikes, Kisaki area, eastern Tanzania: Implications for rare earth elements mineralization","authors":"Almachius Tryphone Mutasingwa ,&nbsp;Akira Imai ,&nbsp;Kotaro Yonezu ,&nbsp;Akane Ito ,&nbsp;Saefudin Juhri","doi":"10.1016/j.jafrearsci.2025.105984","DOIUrl":"10.1016/j.jafrearsci.2025.105984","url":null,"abstract":"<div><div>The Wigu Hill Carbonatite is a rare-earth element (REE) deposit characterized by NW-SE and NE-SW dikes. This study combines field observations, petrography, X-ray diffractometry (XRD), X-ray fluorescence Spectroscopy (XRF), and laser ablation ICP-MS in order to understand the formation processes of the carbonatite dikes and the associated REE mineralization. The study outlines three stages in Wigu Hill Carbonatite formation: (1) the magmatic stage that includes magnetite-dolomite (Mag-Dol), apatite-dolomite (Ap-Dol), and the brecciated apatite-dolomite (brecciated Ap-Dol) carbonatites; (2) the transitional (brine-melt) stage, which includes synchysite-bastnäsite-dolomite (Syn-Bsn-Dol) and monazite-dolomite 1 (Mnz-Dol_1) carbonatites, which form by replacing the hexagonal precursor phases, and (3) the carbo-hydrothermal stage, which includes monazite-dolomite carbonatite 2 (Mnz-Dol_2) without hexagonal precursor phases. Geochemical data show that Mag-Dol has low concentrations of total light rare earth elements (∑LREE) (&lt;0.05 wt%) and total REE oxides (TREE₂O₃) (&lt;0.1 wt%). In contrast, Ap-Dol has higher contents with ∑LREE at 0.3 wt% and TREE₂O₃ at 0.5 wt%. The brecciated Ap-Dol contains ∑LREE at 1.1 wt% and TREE₂O₃ at 1.6 wt%. The Syn-Bsn-Dol contains ∑LREE at 8.9 wt% and TREE₂O₃ at 12.3 wt%. Similarly, Mnz-Dol_1 contains ∑LREE at 9.1 wt% and TREE₂O₃ at 12.6 wt%, marginally exceeding the Syn-Bsn-Dol. The Mnz-Dol_2 has ∑LREE at 6.3 wt% and TREE₂O₃ at 7.4 wt%. The REE mineralization occurred due to magmatic differentiation processes, which intensified from magmatic to transitional (brine-melt) stages, involving (1) differentiation of primary carbonatitic melts, (2) dissolution and replacement of hexagonal precursor phases, and (3) redistribution of dissolved REE into insoluble phases such as monazite.</div></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"235 ","pages":"Article 105984"},"PeriodicalIF":2.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837034","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}