Seismic stratigraphy of the NW Moroccan Atlantic continental shelf and Quaternary deformation at the offshore termination of the southern Rif front [Stratigraphie sismique du plateau continental NW atlantique marocain et déformations quaternaires à la terminaison occidentale du front sud-rifain]
Maad N.,European University of Brittany |
Maad N.,CNRS Oceanic Domains Laboratory |
Maad N.,Laboratoire geosciences marines |
Le Roy P.,European University of Brittany |
And 11 more authors.
Comptes Rendus - Geoscience | Year: 2010
A recent high resolution seismic survey was carried out along the North-West Moroccan Atlantic continental shelf to perform sequence stratigraphy and to better understand the link between the onshore observations across the western termination of the Rif front and the multibeam bathymetric data previously collected across the Gulf of Cadiz. Seismic interpretation clearly shows evidence of deformation affecting the Pleistocene sedimentary cover. This is mainly located between the Lalla Zahra ridge and the Neogene nappes that outcrop at the seabed to the North of Larache, where the identified structures bound the upper part of a gravitationally spreading lobe and are interpreted to be developed by activation of the major tectonic structures located at the southern front of the Rif Cordillera. The offshore extension of the Lalla Zahra Ridge is characterised by an east-west trending major folded and faulted corridor. This structure marks the active front of Prerifan area and corresponds to a major Quaternary kinematic boundary in the western prolongation of the ENE-WSW trending Jebha fault. © 2010 Académie des sciences.
Ali S.,University of Kiel |
Stattegger K.,University of Kiel |
Garbe-Schonberg D.,University of Kiel |
Kuhnt W.,University of Kiel |
And 2 more authors.
International Journal of Earth Sciences | Year: 2014
The petrography, heavy mineral analysis, major element geochemical compositions and mineral chemistry of Early Cretaceous to Miocene-Pliocene rocks, and recent sediments of the Tarfaya basin, SW Morocco, have been studied to reveal their depositional tectonic setting, weathering history, and provenance. Bulk sediment compositional and mineral chemical data suggest that these rocks were derived from heterogeneous sources in the Reguibat Shield (West African Craton) including the Mauritanides and the western Anti-Atlas, which likely form the basement in this area. The Early Cretaceous sandstones are subarkosic in composition, while the Miocene-Pliocene sandstones and the recent sediments from Wadis are generally carbonate-rich feldspathic or lithic arenites, which is also reflected in their major element geochemical compositions. The studied samples are characterized by moderate SiO2 contents and variable abundances of Al2O3, K2O, Na2O, and ferromagnesian elements. Binary tectonic discrimination diagrams demonstrate that most samples can be characterized as passive continental marginal deposits. Al2O3/Na2O ratios indicate more intense chemical weathering during the Early Cretaceous and a variable intensity of weathering during the Late Cretaceous, Early Eocene, Oligocene-Early Miocene, Miocene-Pliocene and recent times. Moreover, weathered marls of the Late Cretaceous and Miocene-Pliocene horizons also exhibit relatively low but variable intensity of chemical weathering. Our results indicate that siliciclastics of the Early Cretaceous were primarily derived from the Reguibat Shield and the Mauritanides, in the SW of the basin, whereas those of the Miocene-Pliocene had varying sources that probably included western Anti-Atlas (NE part of the basin) in addition to the Reguibat Shield and the Mauritanides. © 2013 Springer-Verlag Berlin Heidelberg.
Tari G.,OMV Austria Exploration and Production GmbH |
Geological Society Special Publication | Year: 2013
The Moroccan salt basin appears to be very unique in the sense that it is not sedimentary loading but tectonic inversion which appears to drive the latest stages of salt-related deformation in the central part of the basin. The gravity potential to maintain salt tectonics is provided by the differential uplift of the Atlas Mountains, located adjacent and striking almost perpendicular to the margin. Along the offshore part of the Moroccan salt basin there are many play types, most of them related to the Triassic syn-rift salt. Toe-thrust anticlines at the basinwards edge of the salt basin form very large structures. Traps associated with salt tongues and diapirs define a more 'classical' salt-flank play. Numerous salt tongues, sheets and canopy complexes provide for a 'Gulf of Mexico-style' subsalt play. Despite the numerous untested play types, there have been only four deep-water exploration wells drilled in the entire Moroccan salt basin, none of them having subsalt penetrations. © The Geological Society of London 2013.
Aquit M.,University of Kiel |
Kuhnt W.,University of Kiel |
Holbourn A.,University of Kiel |
Chellai E.H.,Cadi Ayyad University |
And 3 more authors.
Cretaceous Research | Year: 2013
Lithological evidence, benthic foraminiferal census counts, and X-ray fluorescence (XRF) scanner-derived elemental data were integrated with planktonic foraminiferal biostratigraphy and bulk carbonate stable isotopes to retrace the Turonian to early Campanian paleoenvironmental evolution and sea-level history of the Tarfaya Atlantic coastal basin (SW Morocco). The lower Turonian is characterized by laminated organic-rich deposits, which contain impoverished benthic foraminiferal assemblages, reflecting impingement of the oxygen minimum zone on the shelf during a sea-level highstand. This highstand level is correlated to the global transgressive pulse above the sequence boundary Tu1. The appearance of low-oxygen tolerant benthic foraminiferal assemblages dominated by Gavelinella sp. in the middle to upper Turonian indicates an improvement in bottom water oxygenation, probably linked to offshore retraction of the oxygen minimum zone during a regressive phase. This interval is marked by major regressive events expressed by a series of erosional truncations associated with the prominent sequence boundaries Tu3 and/or Tu4. Dysoxic-anoxic conditions recorded in the upper Santonian of the Tarfaya Basin coincide with the eustatic sea-level rise prior to Sa3 sequence boundary. The lower Campanian transgression, only recorded in the southern part of the Tarfaya Basin, coincided with substantial deepening, enhanced accumulation of fine-grained clay-rich hemipelagic sediments and improved oxygenation at the seafloor (highest diversity and abundance of benthic foraminiferal assemblages). Stable isotope data from bulk carbonates are tentatively correlated to the English Chalk carbon isotope reference curve, in particular the Hitch Wood Event in the upper Turonian, the Navigation Event in the lower Coniacian, the Horseshoe Bay Event in the Santonian and the Santonian/Campanian Boundary Event. © 2013 Elsevier Ltd.
Le Roy P.,CNRS Oceanic Domains Laboratory |
Sahabi M.,Laboratoire geosciences marines |
Maad N.,Laboratoire geosciences marines |
Rabineau M.,CNRS Oceanic Domains Laboratory |
And 8 more authors.
Marine and Petroleum Geology | Year: 2014
This study focuses on the evolution of the Atlantic NW Moroccan Rharb continental shelf during the Neogene and Quaternary. This region is part of a foreland basin bounded by the Rif mountain belt and thus provides an interesting geological setting to study the interactions between eustasy and tectonics and the driving mechanisms controlling stratigraphic patterns. The results are supported by an interpretation of new data including high-resolution seismic lines coupled with an interpretation of industrial seismic lines and detailed logs of industrial wells completed by micropaleontologic analysis of cuttings. The stratigraphy reveals a succession of three mega sequences related to the transition from an underfilled to an overfilled stage reflecting the long-term evolution of the foreland system. Moreover, evidence of cyclical sea-level changes are visible in the upper megasequence composed of three depositional sequences assumed to be fourth-order sequences generated in response to the most recent 100-ka glacio-eustatic cycles. This study also shows the peripheral deformation of the Rharb shelf responsible for changes in the geometry of the deposits and thicknesses of the sedimentary fill during the Pliocene and Pleistocene. The most important change was triggered by the uplift of the Lallah Zahra Ridge corresponding to a major Quaternary kinematic boundary and the broad uplift of the southern shelf interpreted as a flexural uplift of the forebulge domain. The deformation-controlled sediment dispersal pattern consists of a progressive growth of the shelf accompanied with a progressive shift of depocenters from the North East to the South West and a general progradation to the North West along the southern border. This progressive filling has led to the confinement of the Rharb paleo-valley across the continental shelf. The complete filling of the palaeo-valley was followed by the development of a more than 70-m thick prodeltaic lobe at the front of the Oued Sebou river mouth during the Holocene. © 2013 Elsevier Ltd.