AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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Inverted structures of the Atlantic margin of Morocco versus the Syrian Arc structures of the Eastern Mediterranean: how analogous are they?

Abstract

Late Cenozoic to Recent inversion and uplift of the Atlas system, as the result of African-Eurasian plate convergence, is well documented in the onshore Essaouira Basin and the western High Atlas of Morocco. However, various 2D and 3D seismic reflection data sets acquired in the offshore Essaouira-Safi segment of the Atlantic margin of Morocco also show the presence of similar compressional structures in the deepwater area as well. These prominent structures are best imaged outboard of the widespread salt basin, some 200 km to the west from the coastline, in water depth of 2,000-4,000 m. The anticlines have a general WNW-ESE trend, perpendicular to the overall strike of the Central Atlantic margin. Whereas the growth history of similar anticlines in the onshore part of the Essaouira Basin are poorly dated due to the erosion of the Cenozoic cover, the continuous sedimentation in the deepwater offers the possibility to directly age-date the propagation of the Atlas mountain building episodes into the Atlantic deepwater region. Compressionally reactivated syn-rift normal faults are responsible for these inverted structures which clearly involved the pre-Mesozoic basement. Structurally analogous inverted features are well documented along the northeastern African-northern Arabian margin (Syrian Arc), mostly onshore. These large-scale, northeast-trending asymmetric folds and associated contractional faults are well-dated and their initial formation is attributed to the late Cretaceous “Santonian event” observed in many parts of the African plate. The late Cenozoic Syrian Arc style compressional features are also present in the deepwater of the Eastern Mediterranean providing the traps for the large deepwater gas discoveries in the Levant in the last decade. The understanding of the similarities and differences between the inverted structures of the Atlas system and those of the Syrian Arc in the Eastern Mediterranean may have important implications for hydrocarbon exploration in Morocco.