Journal of African Earth Sciences最新文献_第6页

Carbonate diagenesis and Mn-carbonate formation in the Paleoproterozoic Francevillian succession (Lastoursville sub-basin) of Gabon 加蓬古元古代Francevillian演替（Lastoursville次盆地）碳酸盐岩成岩作用与锰-碳酸盐岩形成

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-13 DOI: 10.1016/j.jafrearsci.2025.105971

Kevin Xavier Nzamba , Hele-Riin Juhkama , Mathieu Moussavou , Karen Bakakas Mayika , Timmu Kreitsmann , Aivo Lepland , Anthony R. Prave , Kalle Kirsimäe

The Franceville Basin of Gabon contains one of the best-preserved records of Earth's Paleoproterozoic surface environments that began with the oxygenation of the atmosphere and its association with the largest known positive carbonate carbon isotope (δ¹³C_carb) excursion – the Lomagundi-Jatuli Event (LJE). In this study, we conducted a detailed petrographic, mineralogical, and geochemical characterization of carbonate rocks to assess the influence of authigenic and diagenetic processes affecting the primary δ¹³C_carb record preserved in core LST12 obtained in the Lastoursville sub-basin. Previous studies reported an up-section trend in δ¹³C_carb from positive values (5–9 ‰) to near-zero, and further to negative values (−5 to −17 ‰). This δ¹³C_carb shift marking the termination of the typical LJE isotopic signature coincides with changing depositional facies settings. Our new results show that this isotopic shift parallels changes in carbonate mineral composition from stoichiometric dolomite with minor early diagenetic Fe-rich dolomite overgrowths to increasingly Fe- and Mn-rich carbonates formed under sediment-buffered, closed-system diagenetic conditions. The formation of complex diagenetic Ca-Mn-Fe-rich carbonate phases in the topmost manganiferous black shales of core LST12, however, was driven by open-system diagenesis. This involved microbial remineralization of organic matter during progressive basin restriction and dynamic hydrothermal influx. The declining δ¹³C_carb trend in carbonate lithologies of LST12 core is therefore interpreted to record syn-depositional variations in the dissolved inorganic carbon pool, reflecting changing environmental conditions in the Paleoproterozoic Francevillian basin.

加蓬的Franceville盆地包含保存最完好的地球古元古代表面环境记录之一，该记录始于大气的氧化作用，并与已知最大的正碳酸盐碳同位素（δ13Ccarb）迁移- Lomagundi-Jatuli事件（LJE）有关。在本研究中，我们对该区的碳酸盐岩进行了详细的岩石学、矿物学和地球化学表征，以评估自生和成岩作用对Lastoursville次盆地LST12岩心保存的原始δ13Ccarb记录的影响。前人研究表明，δ13Ccarb具有从正值（5 ~ 9‰）到接近零，再到负值（- 5 ~ - 17‰）的上升趋势。这种δ13Ccarb位移标志着典型LJE同位素特征的终止，与沉积相环境的变化相吻合。我们的新结果表明，这种同位素转变与碳酸盐矿物组成的变化是一致的，从早期成岩阶段少量富铁白云岩过度生长的化学计量白云岩到沉积缓冲、封闭系统成岩条件下形成的日益富铁和富锰的碳酸盐。而LST12岩心上部含锰黑色页岩中富ca - mn - fe复杂成岩碳酸盐相的形成是受开放体系成岩作用驱动的。这涉及到在进行性盆地限制和动态热液流入过程中有机质的微生物再矿化作用。因此，LST12岩心碳酸盐岩岩性δ13Ccarb下降趋势被解释为记录了古元古代法兰西盆地溶解无机碳池的同沉积变化，反映了古元古代法兰西盆地环境条件的变化。

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引用次数: 0

Hydrochemistry and pollution assessment of groundwater in the Dodoma: Implications of indices and multivariate statistics Dodoma地下水的水化学和污染评价：指数和多元统计的意义

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-13 DOI: 10.1016/j.jafrearsci.2025.105974

Uwezo Frank Mao , Benatus Norbert Mvile , Mahamuda Abu , Emmanuel Sulungu

Groundwater is the primary source of freshwater in arid and semi-arid regions such as Dodoma, Tanzania, where surface water is scarce. This study assessed the hydrochemical characteristics and pollution status of groundwater in the Dodoma region using water quality indices and multivariate statistical approaches. Thirty-five groundwater samples were collected from boreholes distributed across different geological and land-use settings. Laboratory analyses revealed that the groundwater is generally alkaline (pH 5.8–8.2) with total dissolved solids (TDS) ranging from 135 mg/L to 1780 mg/L and electrical conductivity (EC) between 210 μS/cm and 2740 μS/cm. The dominant cations and anions followed the order Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and Cl⁻ > SO₄²⁻ > HCO₃⁻ > NO₃⁻, respectively. Piper and base-exchange plots classified the groundwater as mainly of the Cl(SO₄)–Na and Na⁺–SO₄^2- types, indicating mineralization dominated by rock–water interaction and evaporation. The Pollution Index of Groundwater (PIG) classified 74.3 % of samples as insignificantly polluted, 17.1 % as low pollution, and 8.6 % as moderate pollution, while the Percentage Pollution Index (PPI) indicated that contamination was primarily anthropogenic. Water Quality Index (WQI) values ranged from 42 to 255, showing that 61.2 % of samples were of poor to very poor quality for drinking. Irrigation suitability assessment showed that 97.1 % of samples were suitable for salt-tolerant crops based on the permeability index and salinity hazard classification. Overall, groundwater mineralization in Dodoma is controlled by both geogenic and anthropogenic processes, emphasizing the need for regular monitoring and mitigation of human-induced contamination.

地下水是干旱和半干旱地区淡水的主要来源，如坦桑尼亚的Dodoma，那里的地表水稀缺。采用水质指标和多元统计方法，对多马地区地下水的水化学特征和污染状况进行了评价。从分布在不同地质和土地利用环境中的钻孔中收集了35个地下水样本。实验室分析表明，地下水总体呈碱性（pH值5.8 ~ 8.2），总溶解固形物（TDS）在135 ~ 1780 mg/L之间，电导率（EC）在210 ~ 2740 μS/cm之间。优势阳离子和阴离子依次为Na+ >； Ca2+ > Mg2+ >； K+和Cl−>； SO42−> HCO3−> NO3−。Piper和base-exchange样地将地下水划分为Cl(SO4) - Na型和Na+ - so42 -型，表明成矿作用以岩水相互作用和蒸发为主。地下水污染指数（PIG）将74.3%的样本划分为轻度污染，17.1%为低污染，8.6%为中度污染，而百分比污染指数（PPI）表明污染主要是人为污染。水质指数（WQI）值介于42至255之间，表明61.2%的样本水质差至极差。灌溉适宜性评价结果表明，97.1%的样品适合种植耐盐作物。总体而言，Dodoma的地下水矿化受到地质和人为过程的控制，强调需要定期监测和减轻人为污染。

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引用次数: 0

Evolution of the Suhum Basin of the Rhyacian Birimian terrane in Ghana: Insight from paraschist and orthoamphibolite 加纳里亚纪- Birimian地体Suhum盆地的演化：来自副长岩和正角闪岩的启示

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-13 DOI: 10.1016/j.jafrearsci.2025.105978

Daniel Kwayisi , Susanna S. Boateng , Naa A. Agra , Solomon Anum , Raymond W. Kazapoe , Abigail E. Ayikwei , Chris Y. Anani , Daniel K. Asiedu

We present petrographical and geochemical data of paraschists and orthoamphibolite from the Suhum-Akwadum area of the Suhum Basin, Ghana, to determine their provenance, petrogenesis, and tectonic setting, and discuss the crustal evolution of the Rhyacian Birimian terrane of the West African Craton. The amphibolite exhibits trace element signatures similar to those of subalkaline basalts. Two main geochemical groups are present: (1) dominant arc-rocks with negative Nb-Ta, Ti, low Nb/Th and high La/Nb, and (2) subordinate enriched mid-ocean ridge basalts characterised by moderate to high TiO₂, positive Ta and high Nb/Th value. These compositions are interpreted as formation in a supra-subduction zone setting. The schists are geochemically classified as shales and wackes and have <60 CIA, <70 CIW, moderate to high Al₂O₃/TiO₂ and Na₂O/K₂O, low SiO₂/Al₂O₃, La/Sc, and Ti/Zr values. These geochemical signatures are consistent with low chemical weathering intensity, immature to moderately mature sediments and deposition in an active continental margin setting with sediments sourced from greenstone and granitoid-gneiss complexes of the Rhyacian Birimian terrane. Therefore, the current and previous geochemical data confirm the presence of an arc tectonic setting in the formation of the metasedimentary basins of the Birimian terrane. The overall geochemical data suggest that the greenstones and metasedimentary rocks formed during an orogenic event related to an arc environment where subduction zone components contributed to the generation of their parental magmas and sedimentation. This finding is consistent with the onset of “modern-style” subduction-related processes during the Archean-Paleoproterozoic transitional period.

本文介绍了加纳苏胡姆盆地Suhum- akwadum地区的副长岩和正角闪岩的岩石学和地球化学资料，确定了它们的物源、岩石成因和构造背景，并讨论了西非克拉通Rhyacian Birimian地体的地壳演化。角闪岩具有与亚碱性玄武岩相似的微量元素特征。主要有两个地球化学类群：(1)以负Nb-Ta、负Ti、低Nb/Th和高La/Nb为主的优势弧岩；(2)以中~高TiO2、正Ta和高Nb/Th为特征的次级富集洋中脊玄武岩。这些成分被解释为位于超俯冲带背景下的地层。片岩地球化学分类为页岩和碎屑岩，具有60 CIA和70 CIW，中高Al2O3/TiO2和Na2O/K2O，低SiO2/Al2O3、La/Sc和Ti/Zr值。这些地球化学特征与低化学风化强度、未成熟到中成熟的沉积物和沉积在活动大陆边缘环境下的沉积物相一致，沉积物来源为流序- Birimian地体的绿岩和花岗岩-片麻岩杂岩。因此，目前和以往的地球化学资料证实，在Birimian地体的变质沉积盆地形成过程中存在弧形构造环境。综合地球化学资料表明，绿岩和变质沉积岩形成于一个与弧环境有关的造山事件中，俯冲带成分促进了母岩浆和沉积的产生。这一发现与太古宙-古元古代过渡时期“现代式”俯冲作用的发生相一致。

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引用次数: 0

Basement architecture and structural styles of part of the Nigerian sector of the Chad Basin (Bornu Basin) 乍得盆地（Bornu盆地）尼日利亚部分地区基底建筑与构造样式

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-13 DOI: 10.1016/j.jafrearsci.2025.105979

Solomon Nehemiah Yusuf , Ezekiel Yusuf Yenne , Mubarak Umar Faruk

Lineament detection and depth estimation methods based on advanced aeromagnetic data were applied to the Nigerian sector of the Chad (Bornu) Basin to delineate structural framework, basement configuration and evaluate their hydrocarbon significance. Power spectral analysis was used to separate deep and shallow magnetic sources, while Euler deconvolution and finite local wavenumber techniques estimated basement depths and mapped major fault systems. Derivative-based filters such as the second vertical derivatives (SVD), analytic signal and Goussev filter enhanced the definition of intrusive and tectonic features. The interpreted structures mainly trend NE–SW, ENE–WSW, and NNE–SSW, aligning with Pan-African reactivation and Cretaceous rifting that formed the basin. The depth of the basement ranges from 1 to 5 km, while sedimentary thicknesses lie between 2.3 and 5.2 km, suggesting substantial sedimentary sequences conducive to hydrocarbons generation and accumulation. Structural lows align with depocentres related to thermal maturation zones, whereas multiple mapped faults coincide with current deep well sites (Ngamma East-1, Ngor North-1, Kanadi-1, Krumta-1, and Murshe-01). The results confirm that basement geometry and fault-controlled deformation significantly influence hydrocarbon migration pathways within the Bornu Basin.

在乍得（Bornu）盆地尼日利亚段应用基于先进航磁数据的剖面探测和深度估计方法，圈定构造格架、基底构型并评价其油气意义。功率谱分析用于分离深、浅磁源，欧拉反褶积和有限局域波数技术用于估计基底深度和绘制主要断层系统。二阶垂直导数（SVD）、解析信号和Goussev滤波等基于导数的滤波增强了对侵入和构造特征的定义。解释构造以NE-SW、ENE-WSW、NNE-SSW为主，与泛非再活动和白垩系裂陷形成盆地一致。基底深度为1 ~ 5 km，沉积厚度为2.3 ~ 5.2 km，具有丰富的生烃成藏层序。构造低与热成熟带相关的沉积中心对齐，而多个已绘制的断层与目前的深井位置（Ngamma East-1、Ngor North-1、kanadi1、Krumta-1和Murshe-01）一致。结果表明，基底几何形状和断裂控制变形对Bornu盆地油气运移路径有重要影响。

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引用次数: 0

The role of Late Quaternary tectonics in moulding El Daba'a Plateau NW coast of Egypt: Stratigraphic and geophysical insights 晚第四纪构造在塑造埃及El dababa 'a高原西北海岸中的作用：地层学和地球物理见解

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-13 DOI: 10.1016/j.jafrearsci.2025.105969

Hesham M. El-Asmar, Mahmoud Sh. Felfla, Zaki A. Abdel-Fattah, Ehab M. Assal

The El Daba'a Plateau, located along Egypt's northwestern Mediterranean coast, provides an excellent natural laboratory for investigating the interplay between neotectonics and Quaternary coastal evolution. This study integrates geomorphological, stratigraphic, and ground magnetic data to elucidate the plateau's morphotectonic development. The exposed succession comprises the Middle Miocene Marmarica Formation, including the Oasis and Siwa Escarpment Members, unconformably overlain by the Quaternary Alexandria Formation, which consists of Pleistocene–Holocene Third, Second and First aeolianite ridges. Magnetic investigations identified four Late Pleistocene normal faults, striking WNW–ESE and NNW–SSE at Jumaymah–Saniyat Turabiyah and Wadi Abu Samra, associated with vertical displacements of up to 15 m, and two ENE–WSW across the plateau's central part. These faults controlled the formation of coastal escarpments and low-lying embayments, moulding the plateau's present-day morphology. The integration of morphostratigraphic and geophysical datasets highlights novel findings regarding the neotectonic imprint along Egypt's northern passive margin and provides new insights into Late Quaternary crustal deformation and coastal evolution in the southeastern Mediterranean, with implications for regional geohazard assessment and landscape evolution models.

El Daba’a高原位于埃及西北地中海沿岸，为研究新构造与第四纪海岸演化之间的相互作用提供了一个极好的自然实验室。该研究综合了地貌、地层学和地磁资料，阐明了青藏高原的形态构造发育。暴露的序列包括中中新世马尔马里卡组，包括绿洲和Siwa陡坡段，被第四纪亚历山大组不整合覆盖，后者由更新世-全新世第三、第二和第一风成岩脊组成。磁调查发现了4条晚更新世正断层，在Jumaymah-Saniyat Turabiyah和Wadi Abu Samra处走向WNW-ESE和NNW-SSE，垂直位移高达15 m，还有2条ENE-WSW横跨高原中部。这些断层控制了海岸峭壁和低洼港湾的形成，塑造了高原今天的形态。地貌地层学和地球物理数据集的整合突出了埃及北部被动边缘新构造印记的新发现，为地中海东南部晚第四纪地壳变形和海岸演化提供了新的见解，对区域地质灾害评估和景观演化模型具有重要意义。

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引用次数: 0

Deciphering the Cenozoic detrital record of the External Rif Belt (Northern Morocco): insights for the evolution of the NW African Margin 外裂谷带（摩洛哥北部）新生代碎屑记录的破译：对西北非洲边缘演化的启示

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-11 DOI: 10.1016/j.jafrearsci.2025.105970

Juan Carlos Cañaveras, Manuel Martín-Martín

This study investigates the Cenozoic geodynamic, palaeogeographic, and palaeoclimatic evolution of the Moroccan NW African Margin through petrographic analysis of 18 stratigraphic sections across the Maghrebian Flysch Basin and the External Rif Zone. Detrital samples (comprising arenites and microconglomerates) are classified as quartzarenites, sublitharenites, and litharenites. These rocks are dominated by quartz and lithics, with scarce intrabasinal carbonate content. Provenance signatures reveal a polycyclic origin with the presence of low-to medium-grade metamorphic sources, likely derived from pre-Alpine orogens (African Craton, Pan-African belt, and/or Variscan mesetas), with contributions from plutonic intrusions. During the Oligo-Miocene, sections show increased quartz, particularly in distal foreland domains, reflecting tectonic uplift and enhanced recycling. Minor mafic input in the Intrarif/Mesorif suggests episodic oceanic crust or subduction-related volcanic contributions. Palaeoclimate proxies suggest moderate to high chemical weathering, with peak warming and aridity during the Paleocene-Eocene and Middle-Late Miocene intervals. Textural maturity ranges from well-sorted quartzarenites to submature arenites, supported by low content of feldspar and unstable grains content, suggesting a history of prolonged sediment transport, multicyclic recycling, and diagenetic overprinting. Comparative analysis with the South Iberian, North Tunisian, West Adriatic and Moldavidian- Scythian-Moessian Margins show inmature sediments in the internal areas, ultramature sediments close to the foreland and mixed succession of the two formers in intermediate positions. In particular, the South Iberian Margin shares quartz-lithic dominance but lacks metamorphic/plutonic clasts, whereas the West Adriatic Margin is characterized by persistent arc-derived volcanoclastics. These disparities highlight distinct geodynamic and palaeogeographic regimes across the Western Tethys during the Cenozoic. Our findings constrain orogenic recycling, sediment routing, and climatic feedbacks in the NW African Margin, providing insights for Mediterranean Alpine belts geodynamic reconstructions.

本文通过对马格里布-弗莱什盆地和外裂谷带18个地层剖面的岩石学分析，探讨了摩洛哥-西北非洲边缘地区的新生代地球动力学、古地理和古气候演化。碎屑样品（包括砂粒岩和微砾岩）分为石英砂粒岩、亚岩屑砂粒岩和岩屑砂粒岩。这些岩石以石英和岩屑为主，基底内碳酸盐含量较少。物源特征显示其为多旋回成因，存在中低变质物源，可能来源于前阿尔卑斯造山带（非洲克拉通、泛非带和/或Variscan mesetas），并有深部侵入的贡献。渐新世至中新世期间，剖面显示石英增加，特别是在远前陆域中，反映了构造隆升和再循环增强。内/中中生代的少量基性输入表明，洋壳或与俯冲有关的火山作用是幕式的。古气候指标显示，古新世—始新世和中新世中后期为中高化学风化期，气候变暖和干旱达到高峰。其结构成熟度从分选良好的石英砂质到亚成熟砂质不等，由较低的长石含量和不稳定的颗粒含量支撑，表明其具有长期的沉积物输运、多旋回再循环和成岩复印的历史。与南伊比利亚、北突尼斯、西亚得里亚海和摩尔达维-斯基泰-莫西边缘的对比分析表明，内部为不成熟沉积，靠近前陆为超成熟沉积，两者在中间位置混合演替。特别是，南伊比利亚边缘以石英岩屑为主，缺乏变质/深成碎屑，而西亚得里亚海边缘则以持续的弧源火山碎屑为特征。这些差异突出了新生代西特提斯地区独特的地球动力学和古地理制度。我们的发现限制了西北非洲边缘的造山带循环、沉积物路径和气候反馈，为地中海高寒带的地球动力学重建提供了见解。

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引用次数: 0

Trend analysis of climate-driven changes in river discharge in Nigeria's benue river basin 尼日利亚贝努埃河流域气候驱动的河流流量变化趋势分析

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-09 DOI: 10.1016/j.jafrearsci.2025.105967

John Ayuba Godwin , Shruti Singh , Ishaku Joshua Dibal , Rajesh Kumar

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 < 0.001; precipitation r = 0.99, p < 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 < 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.

了解气候变率和土地利用变化对水文制度的影响对于可持续水资源管理至关重要，特别是在尼日利亚贝努埃河流域等脆弱地区。本研究分析了1990 - 2023年水文气候变量和土地利用/土地覆盖（LUCC）动态的长期趋势，以评估气候和人类活动对河流流量的综合影响。我们采用非参数Mann-Kendall检验、Sen斜率估计和累积Mann-Kendall方法来检测降水、温度、流量和水位的趋势。利用1990年、2000年、2010年和2020年的Landsat图像量化了土地覆盖变化，并通过高分辨率谷歌地球图像和地面观测进行了验证。结果表明，整个流域显著变暖（Tmax: +2.1±0.3°C），降雨量变率增加，流量减少（- 0.18±0.05单位/年）。Pearson相关系数证实了观测到的和模拟的水文气候变量之间有很强的线性一致性（年流量r = 0.97, p < 0.001；降水r = 0.99, p < 0.001；图5），证实了趋势稳稳性。土地利用与土地覆盖变化分析显示，森林覆盖率下降了21.4%，而农田和城市地区分别扩大了29.7%和38%。回归模型显示，气候变量解释了约29.2%的流量变率，土地利用/土地覆盖变化因子解释了约21.5%的流量变率，两者合计占总变率的50%以上（R2 = 0.51, p < 0.01）。城市化与极端峰值流量密切相关，而森林损失则降低了基流和入渗。这些发现表明，贝努埃盆地的水文变化是气候和人为因素相互作用的结果。采取气候与人类相结合的适应战略，包括重新造林、绿色城市基础设施和土地利用监管，将在不断加剧的环境变化中提高水文恢复能力。

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引用次数: 0

Climatic and tectono-geomorphological controls on karst spring dynamics: Case study of the El Menzel Causse, Middle Atlas (Morocco) 气候和构造地貌对岩溶泉动力学的控制：以摩洛哥中阿特拉斯El Menzel成因为例

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-09 DOI: 10.1016/j.jafrearsci.2025.105972

Iliass Naouadir , Marzieh Khalili , Salih Muhammad Awadh , Samira Adil , El Hassane Chellai , Mohammed Ettaki , Abdennabi Alitane , Abdallah Elaaraj , Zaher Mundher Yaseen

Karst aquifers in semi-arid regions are vital yet exceptionally vulnerable lifelines. This study investigates how tectonic, geomorphological, and climatic factors control the dynamics of karst springs in the El Menzel Causse (Middle Atlas, Morocco). Using an integrated approach that combines field investigations, remote sensing, and quantitative hydro-climatic analysis, we identify the mechanisms driving the system's severe decline. Results indicated that the structural architecture of the major fault systems in the North Middle Atlas Fault (NMAF) and the Median Middle Atlas Fault (MMAF), governs the spatial distribution of more than 50 springs, which occur preferentially within highly permeable fault damage zones. However, the aquifer is under severe climatic stress, evidenced by a statistically significant decline in precipitation and an increased frequency of droughts. The system's response appeared dramatic: only five springs remained active in 2024, with discharge reductions exceeding 80 % compared to historical records. Anthropogenic pressures including groundwater overextraction and wastewater contamination critically amplify this crisis. In conclusion, this research presents El Menzel as a “sentinel system” whose collapse serves as a warning for other karst regions worldwide, highlighting the urgent need for science-informed, adaptive water management strategies to prevent irreversible resource depletion.

半干旱地区的喀斯特含水层是至关重要但又极其脆弱的生命线。本研究探讨了构造、地貌和气候因素如何控制El Menzel Causse （Middle Atlas，摩洛哥）喀斯特泉的动态。通过结合实地调查、遥感和定量水文气候分析的综合方法，我们确定了导致该系统严重衰退的机制。结果表明，北中阿特拉斯断层（NMAF）和中阿特拉斯断层（MMAF）主要断裂系统的构造结构控制了50多个弹簧的空间分布，这些弹簧优先出现在高渗透性断层破坏区内。然而，含水层正处于严重的气候压力之下，从统计数据来看，降水显著减少和干旱频率增加就是明证。该系统的反应非常明显：2024年只有5个弹簧保持活跃，与历史记录相比，排放量减少了80%以上。包括地下水过度开采和废水污染在内的人为压力严重加剧了这一危机。总而言之，本研究将El Menzel作为一个“哨兵系统”，其崩溃为全球其他喀斯特地区敲响了警钟，强调迫切需要科学的、适应性的水资源管理战略，以防止不可逆转的资源枯竭。

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引用次数: 0

The role of facies–diagenesis interactions in shaping geomechanical heterogeneity and mechanical stratigraphy of carbonate reservoirs, Sarvak Formation, southern Iran 伊朗南部Sarvak组碳酸盐岩储层地质力学非均质性和力学地层学的形成与相-成岩作用

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-08 DOI: 10.1016/j.jafrearsci.2025.105968

Samira Akbarzadeh, Sepideh Davoodi, Vahid Tavakoli

The heterogeneous nature of carbonate reservoirs necessitates an integrated evaluation of depositional, diagenetic, and mechanical attributes to predict their reservoir potential. The Sarvak Formation, a key Cretaceous carbonate reservoir in the Zagros Basin, hosts major hydrocarbon reserves in Middle East. This study combines petrographic observations, routine petrophysical measurements, and wireline logs to describe depositional microfacies, diagenetic features, geomechanical units (GMUs), and reservoir rock types. Six microfacies were identified, ranging from distal mid-ramp to lagoonal settings. Various diagenetic processes influence reservoir quality and connectivity of the pores. Four third-order sedimentary sequences were identified from the vertical stacking patterns of the microfacies. According to Lucia's classification, six reservoir rock types were defined, with reservoir quality increasing progressively from RT0 to RT5. Comprehensive geomechanical analyses, including unconfined compressive strength, Young's modulus, shear modulus, and Poisson's ratio, were conducted. The results show that these mechanical properties strongly control reservoir stiffness, ductility, and fracture susceptibility, and consequently influence fluid flow and storage capacity. Based on K-means clustering, four GMUs were identified, exhibiting a progressive increase in reservoir quality. GMU1 is predominantly associated with rock types 0 and 1, whereas GMU4 corresponds mainly to rock type 4, highlighting the systematic relationship between geomechanical behavior and reservoir rock quality. The integrated analysis of microfacies, diagenetic alterations, and geomechanical units demonstrates that reservoir quality improves from GMU1 to GMU4. Early transgressive systems tracts are mechanically stiff and contain limited porosity. In contrast, the overlying regressive systems tracts particularly in sequences 3 and 4, exhibit highly connected pore networks and superior fluid-storage capacity. These findings highlight the critical role of facies–diagenesis interactions in controlling both petrophysical and mechanical properties, providing a robust framework for reservoir characterization.

碳酸盐岩储层的非均质性要求对其沉积、成岩和力学属性进行综合评价，以预测其储层潜力。Sarvak组是Zagros盆地白垩系碳酸盐岩的关键储层，是中东地区主要的油气储量。该研究结合岩石学观察、常规岩石物理测量和电缆测井来描述沉积微相、成岩特征、地质力学单元（gmu）和储层岩石类型。确定了6种微相，范围从中斜坡远端到泻湖环境。不同的成岩作用影响着储层的质量和孔隙的连通性。从微相的垂向叠加模式上，确定了4个三级沉积层序。根据Lucia的分类，确定了6种储层岩石类型，储层质量从RT0到RT5依次递增。综合地质力学分析，包括无侧限抗压强度、杨氏模量、剪切模量和泊松比。结果表明，这些力学性质对储层的刚度、延性和裂缝敏感性有很强的控制作用，从而影响流体的流动和储存能力。基于K-means聚类，确定了4个gmu，表明储层质量逐渐增加。GMU1主要与0、1型岩石相对应，而GMU4主要与4型岩石相对应，突出了地质力学行为与储层岩石质量的系统关系。微相、成岩蚀变和地质力学单元综合分析表明，GMU1 ~ GMU4段储层质量有所改善。早期海侵体系域具有机械刚性，孔隙度有限。相反，上覆的回归体系域，特别是层序3和层序4，表现出高度连通的孔隙网络和优越的储液能力。这些发现强调了相-成岩相互作用在控制岩石物理和力学性质方面的关键作用，为储层表征提供了强有力的框架。

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引用次数: 0

Coastal processes and potentially toxic elements distribution in the western Moroccan Mediterranean coast (Fnideq–Azla) 摩洛哥地中海西部海岸的海岸过程和潜在有毒元素分布（Fnideq-Azla）

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences

Pub Date : 2025-12-05 DOI: 10.1016/j.jafrearsci.2025.105965

Haitam Afilal , Maria-Angela Bassetti , Saida Bouzid , Dominique Aubert , Bruno Charriere , Abdellah Trankil , Bouchta El Moumni , Ayoub El Bakkali , Abdelhamid Rossi

This study assesses the distribution and ecological risk of potentially toxic elements (PTEs: Cd, As, Pb, Cu, Ni, Cr, Zn, Ag) in ten surface marine sediments along the western Moroccan Mediterranean coast (Fnideq–Azla). The results demonstrate that PTE transport and accumulation are mainly driven by continental inputs, marine hydrodynamics, and coastal morphology. Oued Martil represents the main contamination source, pollutants are transported northwestward by longshore drift and subsequently trapped by the Cabo Negro and Ceuta headlands, creating distinct accumulation zones. While the geo-accumulation index (Igeo) shows varying enrichment levels, ranging from uncontaminated (Cr, Cu) to severe (Cd at Oued Martil), the Pollution load index (PLI: 1.19–2.70) indicates widespread anthropogenic impact across the region. Martil is the main pollution hotspot, followed by Fnideq, Cabo Negro, and Azla. The M'diq fishing harbor shows moderate impact, whereas the adjacent M'diq coastline and Restinga remain the least affected. Ecological risk assessment (PERI) highlights very high risk near Oued Martil and considerable risk in the northern sectors of coastal headlands. The total toxic unit (ΣTU) exceeded 3 at most sites, with Ni contributing the highest toxic load. The biological risk index (BRI: 0.17–0.42) reflects moderate risk corresponding to an 11–30 % probability of adverse effects occurring on benthic communities. Except at M'diq and Restinga, PTE levels exceeded the American National Oceanic and Atmospheric Administration (NOAA) safe thresholds. Our results surpass previous regional reports, marking this area as a critical hotspot with escalating contamination patterns.

本研究评估了摩洛哥地中海西部沿岸（Fnideq-Azla） 10种表层海洋沉积物中潜在有毒元素（pte: Cd、As、Pb、Cu、Ni、Cr、Zn、Ag）的分布和生态风险。结果表明，PTE的输运和积累主要受大陆输入、海洋水动力和海岸形态的驱动。Oued Martil是主要的污染源，污染物通过海岸漂移向西北移动，随后被卡波内格罗和休达海岬困住，形成了明显的堆积带。地质累积指数（Igeo）显示出不同的富集水平，从未受污染的（Cr, Cu）到严重的（Oued Martil的Cd），污染负荷指数（PLI: 1.19-2.70）表明该地区广泛存在人为影响。马尔蒂尔是主要的污染热点，其次是芬尼迪克、卡波内格罗和阿兹拉。M'diq渔港受到的影响中等，而相邻的M'diq海岸线和雷斯廷加受到的影响最小。生态风险评估（PERI）强调Oued Martil附近的风险非常高，沿海岬角北部地区的风险相当大。大部分地点的总毒性单位（ΣTU）超过3，其中Ni的毒性负荷最大。生物风险指数（BRI: 0.17-0.42）反映了中等风险，对应于对底栖生物群落发生不良影响的可能性为11 - 30%。除M'diq和Restinga外，PTE水平超过了美国国家海洋和大气管理局（NOAA）的安全阈值。我们的结果超过了以前的区域报告，标志着该地区成为污染模式不断升级的关键热点。

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引用次数: 0