Lahssen Baidder
Hassan II Casablanca, Geology, Faculty Member
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Abstract New Palaeogene vertebrate localities were recently reported in the southern Dakhla area (southwestern Morocco). The Eocene sediment strata crops out on cliffs along the Atlantic Ocean coast. Vertebrate remains come from five... more
Abstract New Palaeogene vertebrate localities were recently reported in the southern Dakhla area (southwestern Morocco). The Eocene sediment strata crops out on cliffs along the Atlantic Ocean coast. Vertebrate remains come from five conglomeratic sandstone beds and are principally represented by isolated teeth belonging to micromammals, selachians and bony fishes, a proboscidean assigned to ?Numidotherium sp. and many remains of archaeocete whales (Basilosauridae). From fieldwork five lithostratigraphic sections were described, essentially based on the lithological characteristic of sediments. Despite the lateral variations of facies, correlations between these five sections were possible on the basis of fossil-bearing beds (A1, B1, B2, C1 and C2) and five lithological units were identified. The lower part of the section consists of rhythmically bedded, chert-rich marine siltstones and marls with thin black phosphorite with organic matter at the base. The overlying units include coarse-grained to microconglomeratic sandstones interbedded with silts, indicating deposition in a shallow-marine environment with fluvial influence. The natural remanence magnetization of a total of 50 samples was measured; the intensity of most of the samples is too weak however, before or after the first step of demagnetization. The palaeomagnetic data from the samples are very unstable, except for eight from three similar sandstone levels which show a normal polarity. Matched with biostratigraphic data on rodents, primates, the selachian, sirenian and cetacean faunas, the new carbon isotope chemostratigraphy on organics (1) refines the age of the uppermost C2 fossil-bearing bed to earliest Oligocene time and (2) confirms the Priabonian age of the B1 to C1 levels.
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Abstract Fieldwork, petrographic description and geochemistry are presented for the Upper Jurassic-Lower Cretaceous magmatic intrusions from the Mesozoic Eastern High Atlas in Morocco. The magmatic complexes are ellipsoid-shaped and a... more
Abstract Fieldwork, petrographic description and geochemistry are presented for the Upper Jurassic-Lower Cretaceous magmatic intrusions from the Mesozoic Eastern High Atlas in Morocco. The magmatic complexes are ellipsoid-shaped and a diapiric-dominated mechanism is suggested for the emplacement of the intrusions into Paleozoic faulted basement as well as in the overlying Triassic-Jurassic sedimentary rocks. The intrusions are massive and composed of mafic (olivine-, biotite-bearing gabbro, and ordinary gabbro), intermediate (diorite) and felsic (syenite) units. The major and trace element contents indicate transitional to alkaline affinities for the mafic and intermediate intrusions and alkaline for the felsic ones, evolved in an intracontinental setting. The data indicate a heterogeneous mantle source, likely metasomatized sub-continental lithosphere that had been enriched by plume-type melts. The Eastern High Atlas intrusives are part of a continuum of magmatic events that spanned from the Triassic Central Atlantic Magmatic Province to the late-Jurassic to early-Cretaceous magmatism of the High Atlas system.
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The long-known Devonian of the Jebel Ardouz west of Marrakesh, and just north of Mzoudia, is composed of an allochthonous stack of clastic and carbonate rocks that were thrusted onto each other from the northeast. New biostratigraphic... more
The long-known Devonian of the Jebel Ardouz west of Marrakesh, and just north of Mzoudia, is composed of an allochthonous stack of clastic and carbonate rocks that were thrusted onto each other from the northeast. New biostratigraphic data prove an age range of sedimentation from the lower Eifelian to ?upper Famennian. The lowest, western thrust unit is composed of reddish sandstones and conglomerates/breccias (new Ardouz Formation) deposited originally by rockfall and debris flows on the slope of a repeatedly active fault scarp. Limestone clasts yielded sandstones of unknown age, Eifelian, Givetian and lower/middle Frasnian conodonts, and encrusted reef corals. Re-sedimentation may have occurred in the upper Frasnian or post-dated the Famennian. The "red conglomerates" record a block that was strongly tilted by Eovariscan extensional tectonics, forming on the uplifted side a small island. Exhumation, erosion down into Eifelian carbonates, and a long phase of reworking (pe...
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<p>A) lateral view, B) dorsal view, C) ventral view, D) Cross sectional morphology. Abbreviations: f: foramina, ssh: symphyseal shelf, me: midline eminence. Scale bar: 5 cm.</p
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Late Viséan brachiopods from the eastern Tafilalt (Morocco), and more precisely from the area comprised between the Jebel Begaa to the southwest, and Gara El Itima to the northeast (close to the Algerian border), are described... more
Late Viséan brachiopods from the eastern Tafilalt (Morocco), and more precisely from the area comprised between the Jebel Begaa to the southwest, and Gara El Itima to the northeast (close to the Algerian border), are described systematically for the first time. Despite the limited material available, 18 species belonging to 17 genera have been recognized within the limestone beds of the Merdani and Zrigat formations, in which the productides (Productidina) and spiriferides are the most diverse. Representatives of the subfamily Gigantoproductidinae, which are close, if not conspecific, to those present in contemporaneous rocks of the nearby Béchar Basin (Algeria), occur in the late Viséan Zrigat Formation. Additional research based on more abundant material is necessary to investigate thoroughly the relationships existing between the Béchar Basin and the Tafilalt, which may have been part of the former during the Carboniferous. Copyright © 2015 John Wiley & Sons, Ltd.
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The transition from the Cambrian to Ordovician in Morocco is known to be characterized by a frequent Furongian hiatus, restricted extension of the Tremadocian marine deposits, and frequent unconformities at the base of the transgressive... more
The transition from the Cambrian to Ordovician in Morocco is known to be characterized by a frequent Furongian hiatus, restricted extension of the Tremadocian marine deposits, and frequent unconformities at the base of the transgressive upper Floian deposits. In the present work, we first highlight the occurrence of Fe- and mica-rich, red silty/sandy formations in the Central and Eastern High Atlas between the Middle Cambrian and Upper Floian sequences. In the Tislyt type-locality, a synsedimentary hemigraben structure is defined, within which the red beds show frequent slump folds, debris flows and internal unconformities. The correlation with several coeval series of the Meseta domain allows us to define a shallow marine, ferruginous clastic Atlas-Meseta Red Beds (AMRB) basin during the Tremadocian-early Floian. The AMRB basin extended between the Meseta coastal block and the Anti-Atlas domain, being limited by the fault zones that became the West Meseta shear zone and the South M...
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ABSTRACTThe study examines bioclastic carbonate contourites that arise from the broad spectrum of bottom‐current related sedimentary processes ranging from deposition to erosion. The result of the intermittent accumulation of sediment are... more
ABSTRACTThe study examines bioclastic carbonate contourites that arise from the broad spectrum of bottom‐current related sedimentary processes ranging from deposition to erosion. The result of the intermittent accumulation of sediment are thin and condensed successions with abundant hiatuses. Such bottom‐current deposits are poorly known, since the broadly accepted contourite‐facies model, the bi‐gradational sequence, characterizes environments of contourite depositional systems as a continuous accretion of fine‐grained siliciclastic sediments. To increase current understanding of the carbonate facies within hiatal contourite records, the Eifelian–Frasnian of the Tafilalt Platform in Morocco was investigated. The succession is divided into five facies associations that are interpreted to reflect pelagic sedimentation and deposition from bottom currents on a contourite terrace, a gently inclined section of the upper slope of Gondwana shaped by a water‐mass interface. Contourite deposition was mainly controlled by oxic clear‐water currents (documented by moderately to completely bioturbated limestones with abundant hydrogenetic ferromanganese nodules, and low organic‐carbon contents), at times also by an anoxic water mass (featured by organic‐rich coquinas with absent to sparse bioturbation and predominantly syngenetic framboidal pyrites). Biostratigraphic data and the overall depositional architecture display palaeoceanographic hydrodynamic processes associated with a shifting water‐mass interface. The inner terrace was characterized by an alongslope contourite channel and a small mounded drift at its downslope margin. Energetic bottom currents furthermore caused abraded surfaces, i.e. plain areas of non‐deposition and localized erosion, and sandy condensation layers. The microfacies reflects repeated alternation between suspension deposition, winnowing of fines, bedload traction, dynamic sediment bypassing and reworking, together with concomitant seafloor cementation. Coquinas of mainly planktonic and nektonic organisms are identified as integral parts of bi‐gradational contourite sequences showing inverse and normal grading. Hiatal lag concentrations of carbonate intraclasts, ferromanganese nodules and conodonts often drape hardgrounds and erosional surfaces at the midpoint of these frequently incomplete sequences. This Devonian case provides the opportunity to investigate the spatial and temporal variability of the bed‐scale contourite sequence, also with regard to the drift‐scale depositional architecture. In addition, the identified high‐resolution record is a starting point for unravelling the pattern of oceanic circulation in the Devonian greenhouse world.
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Purpose. The purpose of the present research is to provide a new lithological, structural and magmatic features of the Oumjrane-Boukerzia Mining District. The results obtained are used to guide exploration works for identifying the new... more
Purpose. The purpose of the present research is to provide a new lithological, structural and magmatic features of the Oumjrane-Boukerzia Mining District. The results obtained are used to guide exploration works for identifying the new Cu, Ni, Pb, Zn depositions and Ba-bearing mineralization within the whole Oumjrane-Boukerzia domain. Methods. This research is based on detailed mapping, structural surveys and geochemical studies performed on the magmatic rocks in the studied area. Findings. Structural and microstructural analyses of the studied area have revealed three complex polyphase tectonic events related to the Variscan orogeny: (i) an extensive phase during the Devonian period; (ii) a NW-SE compressional phase of Namuro-Westphalian age; (iii) a NE-SW compressional phase of Stephanian-Autunian age, and (iv) an extensive late phase probably related to the opening of the Central Atlantic ocean during the Late Trias-Jurassic periods. The sedimentary rocks of the district are loca...
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Research Interests: Geology and Geophysics
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Research Interests: Geology, Geochemistry, Geophysics, Geodynamics, Permian, and 4 moreRIFT, Geomatic Engineering, Magmatism, and Craton
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North of the Saharan cratonic domain, the Anti-Atlas mountains correspond to the foreland, external fold belt of the Variscan orogen which extends in the Meseta block to the north, and Mauritanides to the southwest. The Anti-Atlas was... more
North of the Saharan cratonic domain, the Anti-Atlas mountains correspond to the foreland, external fold belt of the Variscan orogen which extends in the Meseta block to the north, and Mauritanides to the southwest. The Anti-Atlas was uplifted during the Mesozoic-Cenozoic, and display several basement culminations (“boutonnières”) amidst the folded Palaeozoic cover. Recent studies in western Anti-Atlas emphasized the basement implication in the shortening process (thick skinned structure). Hereafter we investigate the cover-basement relations in eastern Anti-Atlas south of the Ougnat culmination, based on mapping at scale 1:50,000. The Palaeozoic sequence is much thinner than in the west, and the décollement levels are less important. Flexural slip folds are concentrated along the faults (en échelon folds) and within some rhombic domains crushed between major faults (e.g. Angal-Gherghiz Lozenge), whereas other areas are monoclinal. The main shortening direction deduced from the f...
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Based on new field work, sampling for conodonts, ammonoids, and microfacies analysis, the Lower to Upper Devonian stratigraphy of the Benahmed region is refined. Fossiliferous neritic limestones of the Pragian/lower Emsian represent a... more
Based on new field work, sampling for conodonts, ammonoids, and microfacies analysis, the Lower to Upper Devonian stratigraphy of the Benahmed region is refined. Fossiliferous neritic limestones of the Pragian/lower Emsian represent a continuation of the shallow carbonate platform of the Al Attamna region to the north (Units A/B of Sidi Ahmed Lemdoun Formation). More argillaceous upper Emsian/Eifelian strata are regionally still poorly known. In the southern Chaouїa or Beni Sekten region NW of Benahmed, Givetian deep neritic to shallow pelagic mud-wackestones of the new Oulad Amar Formation were partly reworked and re-sedimented together with crinoidal grainstones in conglomeratic debris flow beds. Peaks of Eovariscan block faulting and reworking occurred high in the middle (ansatus Zone) and at the top of the Givetian (norrisi Zone). Lower/middle Frasnian strata are still unknown in outcrop but limestones with corals of possible Givetian/Frasnian age have been reported from E/SE of...
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The Sub-Meseta Zone forms the transition between the southern Meseta of the main Variscides and the Anti-Atlas realm. The Skoura region at the southern foot of the High Atlas includes a west-east, discontinuous sequence of Devonian and... more
The Sub-Meseta Zone forms the transition between the southern Meseta of the main Variscides and the Anti-Atlas realm. The Skoura region at the southern foot of the High Atlas includes a west-east, discontinuous sequence of Devonian and Lower Carboniferous outcrops, from Tizi-n´Tichka East in the NW of Ouarzazate to Asserhmo in the NE. Based on detailed logging, microfacies, conodont and macrofauna sampling, especially at Taliouine and Tizi n-Ouourti, the regional Devonian litho, bio- and event stratigraphy and facies development is revised. The Lochkovian is marked by a change from unfossiliferous black shales (Lower Member of new Tizi-n-Tichka Formation) to condensed, discontinuous, black, detrital Orthocone Limestones (Upper Member, middle Lochkovian) deposited under strong bottom current influence (contourites). Slumps and a subsequent erosional disconformity mark the regional tectonic episode Sk-TP-1a, followed by a distinctive "Antevariscan" conglomerate and reworking...