High Atlas Research Articles

Coral Moroccan biodiversity after the End-Triassic mass extinction

Each new coral-bearing outcrop found in Lower Jurassic strata is useful to understand the evolution of corals between the end-Triassic mass extinction and the Toarcian anoxic event. Here we provide new taxonomic data on corals issued from fieldwork on four outcrops from the region of Amellagou, in the High Atlas Mountains, Morocco. A set of 157 coral specimens have been collected from a small biostrome, a giant reef and two olistholiths, spanning from Hettangian – Sinemurian time interval to Early Pliensbachian. These corals are distributed in 14 families, 22 genera and 27 species. Among these species, two are new: Lepidophyllia (Heterastraea) microcalix sp. nov., represented enough to allow a population study and Paracuifia castellum sp. nov. The study extends the last appearance datum of several genera known only in the Triassic till now, namely: Parastraeomorpha, Araiophyllum, Paracuifia, Pinacophyllum and, possibly, Paravolzeia. For this reason, the severity of the end-Triassic mass extinction is questioned in comparison to the extinction events that happened around the Pliensbachian-Toarcian boundary. For this reason, moreover, the phyletic discontinuity between some Triassic and Jurassic taxa is also addressed. Some Lazarus taxa known from Triassic and Pliensbachian remain absent in Hettangian and now, at a lesser degree, in Sinemurian. That is why we assume that the absence of these taxa is only due to the poor preservation of coral environments during these times. This study also changes our view on the first appearance datum of several genera that were known in Jurassic strata, namely: Proleptophyllia, Vallimeandropsis and, possibly, Lochmaeosmilia. A special attention is given to the distribution of colonial arrangements and points to the important proportion of cerioid and solitary corals. Additionally, the study highlights the existence of significant proportions of thamnasterioid and meandroid forms. The presence of corals with such a level of integration, together with the occurrence of two species that show platy to ramose transition in their colony shape, namely Hispaniastraea murciana and Chrondrocoenia clavellata, stresses the effectiveness of a photosymbiosis in these Early Jurassic coral communities. Lastly, the proportion of solitary specimens increased over time, revealing the uniqueness of coral assemblages during the Pliensbachian.

Phytochemical Diversity and Biological Effects of Juniperus Thurifera L., Essential Oil : A Comparative Study using In Vitro and In Silico Methods.

Juniperus thurifera L., a plant endemic to the Moroccan High Atlas Mountains, thrives in extreme climatic conditions, resulting in the production of valuable secondary metabolites. This study aims to elucidate the phytochemical diversity and biological activities of J. thurifera essential oil (JTEO) through a comparative analysis of samples from two distinct regions: Tensift-Al Haouz and Azilal, using both in vitro and in silico methods. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed 21 components in the Tensift-Al Haouz JTEO (99.99 % of the oil) and 23 components in the Azilal JTEO (99.58 % of the oil), with oxygenated monoterpenes being the predominant compounds in both. The biological activities were assessed in vitro. Antioxidant properties, evaluated using DPPH, FRAP, and ABTS assays, showed significant activity in both oils. Antibacterial activity was tested against two strains of Gram-positive and two strains of Gram-negative bacteria, with both oils demonstrating notable bacterial growth inhibition. Enzymatic assays assessed the antidiabetic (α-amylase and α-glucosidase), dermo-protective (tyrosinase and elastase), and neuroprotective (AChE and BChE) activities. Both oils displayed substantial inhibitory effects across all tested activities, with variations attributed to their distinct chemical compositions. In silico analyses of six target enzymes confirmed significant binding affinities of the major compounds. Notably, 2,2'-Thiobis(6-tert-butyl-p-cresol) exhibited strong binding affinities with AChE, BChE, α-amylase, α-glucosidase, tyrosinase, and elastase, with binding energies ranging from -10.0 to -6.2 kcal/mol. These findings indicate that JTEO is a rich source of bioactive compounds with promising potential in pharmacological and cosmetic applications.

Geological Sites of the Anergui Region: Description and Place in the Alpine Geological History of the M'goun UNESCO Global Geopark (Morocco)

The M'goun UNESCO Global Geopark is located in the central part of the High Atlas Mountains in Morocco. Numerous studies have highlighted the richness of the geological heritage of this area. Despite these increased efforts in characterization, some areas, such as Anergui, remain underexplored. This mediation work aims to describe the most significant geological landscapes of this region and place them within the broader geological history framework of the UNESCO M'Goun Geopark, thereby enriching the list of geosites within this geopark and promoting geological awareness in the area. This study focused on describing 16 geosites selected based on scientific, educational and geotourism values. These geosites stand out for their geodiversity, showcasing both deep-seated and surface geological phenomena. They provide an excellent framework for understanding the alpine geological history of the M'Goun Geopark. Each site bears witness to one or several key stages of this history, highlighting the extension of the High Atlas basin, the development of carbonate platforms, Jurassic diapirism and magmatism, Late Cretaceous and Tertiary compression, Tertiary and Quaternary uplift, and erosion, resulting in a variety of geological features relating to deformation and alteration.

Relocation of the 8 September 2023 High Atlas, Morocco, Earthquake Aftershock Sequence

ABSTRACT The earthquake that occurred on 8 September 2023, with a magnitude of 6.8, was the most destructive earthquake event in Morocco in the past decade. This earthquake took place in the Al Haouz region, located in the western part of the High Atlas Mountain range. To better understand what caused and triggered this earthquake, the earthquake catalogs including P and S arrival times were collected from the Moroccan seismic network and combined with regional data from the International Seismological Centre. The mainshock and aftershocks were relocated by using iLoc, a state-of-the-art single-event location algorithm, and then by the multiple event location double-difference algorithm, hypoDD. The improved earthquake relocations using iLoc and the double-difference methods provide sharper lineation of seismicity and agree well with tomographic images of the earthquake zone. The seismicity distribution and the focal mechanism of the mainshock indicate that the earthquake sequence has occurred along the South Atlas fault system.

Geology of the Toundoute Region (South Morocco): a window on the Early Jurassic-Cretaceous tectono-sedimentary evolution of the Central High Atlas

ABSTRACT A new geological map representing the southern leading edge of Central High Atlas (Toundoute, South Morocco) updates the stratigraphic architecture of a Lower Jurassic-Cretaceous succession including marine carbonates and terrestrial clastics. Integrated facies and structural analyses outline a marked syn-tectonic control on depositional patterns since the Early Jurassic, as documented by geological maps of adjacent sectors of the Central High Atlas southern flank recently published on Journal of Maps. This incipient diffuse crustal uplift and denudation attests to a pre-collisional stage in the development of the Central High Atlas mountains.

Resolving the ubiquitous small-scale semi-permanent features of the general ocean circulation: a multiplatform observational approach

Abstract Based on twenty years of Argo and ship/animal-borne/glider hydrographic profile data, we derive a new high resolution hydrographic Atlas and associated circulation field for the oceans above 2000 dbar. Satellite altimetric observations are used to explicitly regress out eddy noise in the fit, greatly reducing one of the major sources of noise. Geostrophic shears are found from the fitted geopotential anomaly fields. Ekman velocities are estimated using satellite wind stresses. Both Argo trajectory observations at 1000 dbar and surface drifter observations are used to reference geostrophic shears derived from the Atlas hydrography. Surface drifter velocities are analyzed with an additional wind-friction term to remove the wind-related flow. Agreement between the surface geostrophic (referenced to Argo trajectories) and drifter-based surface velocity is high at both large and mesoscales, lending confidence to the derived geostrophic circulation fields. The Atlas reveals standing mesoscale eddies and meanders in western boundary systems, and the braided jet structure of the Antarctic Circumpolar Current. In the interior, the upper ocean flow consists of a highly baroclinic large-scale Sverdrup flow and smaller scale (~200 km width) semi-zonal jets, which are more barotropic (low vertical shear) and have an average zonal width of around 2000 km. These semi-zonal jets are globally ubiquitous - found in all basins pole-to-pole. The many permanent mesoscale features of the mean general circulation contrasts with that predicted by theories of the large-scale flow in simplified flat-bottomed domains. The new Atlas presents a new opportunity to benchmark modern high resolution ocean and climate models.

Tectonics of the Mw 6.8 Al Haouz earthquake (Morocco) reveals minor role of asthenospheric upwelling

A reliable identification of the fault responsible for the magnitude 6.8 Al Haouz earthquake that struck Morocco on 8 September 2023 has so far been hampered by a lack of accurate tectonic analyses. Here we provide the first updated tectonic framework of the earthquake epicentral area based on original field data. We cast our results into the context of available geomorphological, thermochronological and geophysical constraints, and discuss the earthquake characteristics within the framework of competing tectonic models either based on asthenospheric upwelling or transpressional tectonics. We found that the Al Haouz earthquake was likely generated by rupture along a north-dipping high-angle fault, linking former fault planes belonging to an orogen-scale WSW-ESE transpressional shear zone. The geological evolution and seismotectonic structure of the region are largely governed by the oblique convergence of tectonic plates. The impact of asthenospheric upwelling, if any, remains limited and may only influence the geomorphological evolution of the Western High Atlas, but cannot explain the seismotectonic and geological features observed today at the surface, which are instead effects of transpressional tectonics.

Reflectance spectrometry and multispectral data for mapping fractures and hydrothermal alterations in the northern edge of the eastern High Atlas, Morocco

The Marginal Folds, in the north-western axis of Moroccan eastern High Atlas, are mainly composed of the Infra-Cenomanian terrains. These latter contain continental detrital deposits (red beds) and are characterized by a network of fractures. These marginal folds host significant concentrations of metallic minerals, such as Cu, Pb, Ag, and Zn, particularly at the Merija (Cu) and Bou Sellam (Pb-Zn) sites.Several techniques were applied to the Landsat-8 Oli images to improve the clarity and visibility of the linear features. Radiometric and atmospheric corrections, color compositions, directional filters, and principal component analysis were adopted. The lineaments resulting from automatic extraction, as well as their statistical analysis were validated by visual interpretation and field investigations. Statistical analysis revealed three dominants fracture systems: N-S, NE-SW, and E-W; the first two systems show a high density in the study area.The mineral alteration of the outcropping rocks is well described by ASTER multispectral imaging techniques. In this work, the effectiveness of this techniques for mineral alteration mapping was demonstrated on the Merija area. Several occurrences of mineral alteration were highlighted, using a combination of false color and band ratios, the principal component analysis (PCA), and the band ratios. This research was completed by reflectance spectrometry, covering the visible, near-infrared (VNIR), and short-wave infrared (SWIR) domains, to identify mineral alteration.Hydrothermal alteration in the Merija region includes clay, phyllite, carbonate, and phyllosilicate alteration, such as kaolinite, illite, montmorillonite, palygorskite, and vermiculite. Regarding to oxidation, as evidenced by the presence of goethite, jarosite, and hematite, it is widespread in most of the analyzed samples, resulting from the alteration of pyrite, followed by jarosite and goethite.

Assessing habitat suitability for aoudad (Ammotragus lervia) reintroduction in southeastern morocco to promote ecotourism

The objective of this study is to address the complex task of identifying optimal locations for reintroducing Ammotragus lervia in a semi-arid area in the Eastern High Atlas of Morocco, considering three topographical factors. The study assesses the effectiveness of a commonly used machine learning classifier (MLC) in mapping potential areas for introducing these species, which is crucial for promoting and enhancing local biodiversity. To begin with, an extensive inventory of 88 remaining sites where these Barbary sheep still living was conducted, and precise measurements of three topographical parameters were collected at each site. Subsequently, a machine learning algorithm called Bagging was employed to develop a predictive model. The predictive model demonstrated a high level of performance, as evidenced by an area under the curve (AUC) value of 0.929. Bagging effectively identified favorable areas, encompassing around 13.8 % of the study region, which were predominantly located in the western part. These areas were characterized by mountainous terrain, shorter slopes, and higher altitudes. The research findings provide valuable guidance to decision-makers, offering a roadmap to reintroduce these species for enhancing the local biodiversity in the region.

Dolomite, quartzite, and sand indices defined for PRISMA hyperspectral data. Application to the Tamlalet inlier (Eastern High Atlas, Morocco)

The present work discusses the development of three novel spectral indices for PRISMA data. The Hyperspectral Dolomite Index (HDI) using B2320nm and B2349nm bands, the Hyperspectral Sand Index (HSI) based on the visible B515nm and B596nm bands, and the Hyperspectral Quartzite Index (HQI) using a combination of Relative Band Depths in B2167nm and B2206nm bands. The outputs of the three indices are grayscale images, where the brightest pixels represent the indices target. Applying HDI on PRISMA image of Tamlalet inlier (Moroccan Eastern High Atlas) led to discriminate the dolomites from lacustrine limestones and bare soils. HDI also suggests rectifying the local geological map by replacing limestones with dolomites in Jbel Ain Chair. HQI highlights quartz-rich rocks and provides better results than ASTER TIR indices. HSI can discriminate sand dunes from bare soils without being disturbed by vegetation. Dolomite, Quartzite, and Sand Hyperspectral indices show an overall accuracy of 91.2 %, 97.8 %, and 91.5 %, respectively. These indices could be adapted to other hyperspectral data having the required wavelengths.

Delineation of Groundwater Storage and Recharge Potential Zones Using Multi-Influencing Factors (MIF) Method: Application in Synclinal Coastal Basin of Essaouira (Western High Atlas of Morocco)

Unpredictable rainfall caused by climate change and pollution directly impacts groundwater demand, making the exploitation of groundwater reserves necessary. To achieve this, a study in the synclinal basin of Essaouira (Western High Atlas) used GIS, remote sensing, and the Multi-Influencing Factors (MIF) method, to identify areas ideal for the installation of productive wells. An overlay analysis created a groundwater potential zone (GWPZ) map, showing 30% of the basin with high potential, 51% with moderate potential, and 19% with low to very low potential. The groundwater potential zone map was validated using geophysical surveys, piezometric data, and well water levels, showing a 69.3% prediction accuracy with the ROC curve.

Seismic synthesis of the Al Haouz earthquake of September 8th, 2023 by integrating gravimetric and aeromagnetic data from the western High Atlas in Morocco

Seismic synthesis of the Al Haouz earthquake of September 8th, 2023 by integrating gravimetric and aeromagnetic data from the western High Atlas in Morocco

Early Devonian bioclastic contourites in the High Atlas: a plastered drift recording the convergence between Gondwana and Laurussia (Sub-Meseta Zone, Morocco)

Bottom-current deposits, formed in association with ancient oceanic gateways, preserve records of past global oceanic circulation, plate-tectonic events, and palaeogeographic change. This outcrop study showcases a Pragian to early Emsian carbonate-contourite drift, plastered on the northern upper margin of Gondwana, which recorded the convergence of Laurussia and Gondwana and the (temporal) closure of the nearby American Gateway. The results underscore the value of bed-scale features, including microfacies and primary sedimentary structures, in interpreting bottom-current dynamics. The documented contourite-specific bi-gradational sequences, 40 to 80 cm thick, are largely complete and well-comparable with the standard facies sequence identified in modern oceans. The bioclastic contourites show subtle variations in grain size and mud content in the lower part, distinct sequences of inverse-to-normal grading at different scales in the middle, and a large variety of traction structures in the upper part of the succession. This long-term coarsening-upward trend was caused by a successive increase in maximum bottom-current strength during drift growth. Traction structures such as current ripples and dunes document a westward-directed palaeocirculation of surface or intermediate water during the Pragian-Emsian. They provide evidence of enhanced bottom-current episodes towards the top of the drift, before the contourites were buried by late Emsian shales.

A review of the genus Eugaster Serville, 1838 (Orthoptera, Tettigoniidae, Hetrodinae): a multifaceted approach

Overall coloration, size and thoracic morphology have formed the basis for taxonomic differentiation of taxa within the genus Eugaster at specific or subspecific levels over the years. The present study employs a range of methods to examine the morphology of 58 specimens (18♂♂ and 40♀♀) from Morocco, Algeria and Tunisia, collected from altitudes varying between 10 and 1795 metres AMSL. Moroccan sampling sites include localities on both the north and south of the High Atlas and from either side of the Middle Atlas, i.e., the Anti-Atlas, Western Meseta and High Plateau. The various techniques involve the characterisation of the five key colour forms and an investigation to examine links between colour form and geographical location and altitude, biometric analysis comprising selected variables, thoracic structure examination through feature extraction and edge detection, microscopy to examine male stridulatory files, an examination of the male genital sclerite structure for the presence of titillators, as well as molecular and phylogenetic analysis. Statistical tests are performed for results pertaining to biometrics, thoracic skeletisation, and the number of pegs on stridulatory organs. From results obtained, this study finds no basis to support the notion of the various taxa described in the past being assigned the rank of species and considers these to be infraspecific variants or forms. Consequently, the present authors propose to synonymise Eugaster guyoni (Serville, 1838) with Eugaster spinulosa (Johannson, 1763), resulting in the genus Eugaster being represented in North Africa by a unique but highly variable taxon, in terms of coloration, size and thoracic morphology.

Structural and mineralogical mapping using multispectral satellite data (Aster, Landsat 8 OLI, and Sentinel 2B) combined with field work in the Western High Atlas, Morocco

Structural and mineralogical mapping using multispectral satellite data (Aster, Landsat 8 OLI, and Sentinel 2B) combined with field work in the Western High Atlas, Morocco

Reply to the comment on "Geochemistry, Rb-Sr whole rock age and Sr-Nd isotopic constraints on the Variscan A-type granite from Azegour area in the Marrakech High Atlas (Moroccan Meseta) and their geodynamic implications" by Hadani et al. (2024)

Reply to the comment on "Geochemistry, Rb-Sr whole rock age and Sr-Nd isotopic constraints on the Variscan A-type granite from Azegour area in the Marrakech High Atlas (Moroccan Meseta) and their geodynamic implications" by Hadani et al. (2024)

Comment on "Geochemistry, Rb-Sr whole rock age and Sr-Nd isotopic constraints on the Variscan A-type granite from Azegour area in the Marrakech High Atlas (Moroccan Meseta) and their geodynamic implications" by Hadani et al. (2024): Geologos 30, 1 (2024): 1–16

Comment on "Geochemistry, Rb-Sr whole rock age and Sr-Nd isotopic constraints on the Variscan A-type granite from Azegour area in the Marrakech High Atlas (Moroccan Meseta) and their geodynamic implications" by Hadani et al. (2024): Geologos 30, 1 (2024): 1–16

Exploring spatial variations in geomorphic features of a young intracontinental orogenic belt: A case study of the High Atlas range

Morphotectonic parameters are sensitive to crustal and/or mantle dynamics, especially in young convergent margins and contractional orogenic systems. In northwest Africa, the High Atlas orogen is a natural example where tectonics interact with mantle dynamics to shape the orogen's topography.The High Atlas Mountains are an intracontinental segment of the peri-Mediterranean belt in northwest Africa, formed during the Late Cretaceous-Cenozoic period as part of the Alpine orogeny. An important aspect in the evolutionary history of the High Atlas belt is the presence of uplifted asthenosphere beneath the range, overlaying the Late Cretaceous-Cenozoic crustal shortening. This study aims to investigate the geomorphic and topographic features that reflect the influence of tectonics and mantle dynamics in the High Atlas orogen. A morphotectonic approach is employed, utilizing analysis of geomorphic indices such as relief, slope, channel steepness index, and stream length gradient. Additionally, eleven 30 km wide and 150 to 230 km long swath profiles are constructed to illustrate the variations in topography and geomorphology along the range.The geomorphic indices display a similar pattern of evolution across the High Atlas, with higher values of these indices associated with the primary faults that control the structure of the range. By combining the geomorphic indices and swath profiles, it is evident that the eastern part of the orogen exhibits geomorphic asymmetry, with the northern border experiencing greater neotectonic activity and surface uplift. The central part of the range displays more geomorphic symmetry, while the western part is asymmetrical, characterized by higher elevations and elevated values of geomorphic indices along the southern border. This variation in geomorphology is attributed to the oblique intersection of the High Atlas orogen and a region of thinned lithosphere, which facilitated increased neotectonic activity and surface uplift in the northern part of the Eastern High Atlas and the southern part of the Western High Atlas. In the westernmost portion of the range, the role of structural inheritance is critical in the neotectonic activity. At a local scale, the role of lithology in the drainage reorganization is evident especially in basement exposures such as Mougueur inlier, Skoura inlier and Ouzellarh salient.This study underscores the robustness of tectonic geomorphology as a tool to understand the complex interplay between crustal processes and mantle dynamics, together with surface processes, in young orogenic belts like the High Atlas.

Prediction of current and future gully erosion susceptibility in the Oued Zat watershed in the High Atlas region of Morocco using an SVM-based machine learning approach

Gully erosion constitutes a major natural hazard causing significant land degradation. Here, we aimed to assess the current and future susceptibility of gully erosion in the Oued Zat watershed (High Atlas, Morocco) using machine learning (ML). Leveraging 210 gully and 400 non-gully points along with 16 conditioning factors from precipitation, remote sensing, geological, and soil data, we employed five support vector machine (SVM) models based on linear, radial, and polynomial kernels for gully susceptibility modeling. Performance evaluation included specificity, recall, receiver operating characteristic area under the curve (ROC–AUC), precision, and F1 score metrics. Future vulnerability in the 21st century was assessed under two shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5) climate scenarios. Our results demonstrated superior performance by SVM-Poly (recall: 0.93; AUC–ROC: 0.92; precision: 0.89; F1-Score: 0.91) followed by SVM-RBF (recall: 0.84; AUC–ROC: 0.86; precision: 0.78; F1-Score: 0.81), while linear models were the least accurate. Current predictions showed a prevalence of high- and very high-risk areas to gullying, together accounting for over 38% of the watershed, particularly in the south, while low- and very low-risk areas (26%) dominated in the north. Future projections anticipate declining very low, low, and moderate-risk areas. Initially, high- and very high-risk zones will increase in extent, followed by a gradual decline in very high-risk areas. In contrast, high-risk areas will continue increasing, reaching around 20% and 40% by 2100 under SSP2-4.5 and SSP5-8.5, respectively. Our findings not only reveal vulnerability to erosion but also demonstrate a practical, effective approach for decision-making, especially considering the impacts of climate change in the region.

Litho-structural interpretation of aeromagnetic anomalies reveals potential for mineral exploration in Tizi n'Test Region, Western High Atlas, Morocco

This study interprets aeromagnetic data from the Tizi n'Test area in the High Atlas massif of Morocco, aiming to gain insights into its litho-structural architecture and implications for mineral exploration and mining. We employed six different analytical techniques to the residual magnetic field data, including reduction to the pole (RTP), upward continuation, total horizontal derivative, Tilt angle, Centre for Exploration Targeting (CET) analysis, and Euler deconvolution. Our analyses differentiated the study area into three magnetic domains: the eastern Ouzellarh block, characterized by positive anomalies, a central domain characterized by a negative magnetic signature demarcating the transitional zone between the Anti-Atlas and the High Atlas separated by the Ouchden fault: and the western domain, represented by the Tichka massif. The application of total horizontal derivative, tilt angle, and a combination of filters in ternary image formats (Tilt angle, upward continuation 1000 + Tilt angle and upward continuation 3000 + Tilt angle) revealed both known and previously unidentified geological lineaments, mapping structural complexity across various orientations (NE–SW, NNE–SSE, E–W, NW–SE, and N–S). The CET grid analysis method unveiled the structural complexity, highlighting the geodynamic evolution of the region. Particularly, the Ouchden fault delineates a magnetic domain divide between the ancient High Atlas and the Ouzellarh block (Anti-Atlas). Furthermore, Euler deconvolution indicated magnetic source depths ranging from 52 m in the western domain of the Tichka massif to 6560 m in the Ouzellarh block. A comprehensive structural scheme, classified by C-A fractal analysis, identified zones favourable for exploration and mining, particularly along the Ouchden fault, Tizi n'Test, NE-SW trending lineaments in the northwestern domain, as well as along the Tichka granite’s margin.