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Salt Tectonics in the Atlantic Margin of Morocco*
Gabor Tari1 and Haddou Jabour2
Search and Discovery Article #30061 (2008)
Posted October 30, 2008
*Adapted from oral presentation at AAPG Annual Convention, San Antonio, Texas, April 20-23, 2008.
1 AllyGabor Geoscience, Bellaire, TX; currently OMV, Vienna, Austria ([email protected])
2 ONHYM, Rabat, Morocco ([email protected])
The Moroccan salt basin on average is ~50-150 km in width, but it stretches for at least 1000 km between the leading edge of the offshore pre-Rifean nappe in the north and the Canary Islands in the south. The significant along-strike variations in the cross
-sectional and map-view distribution of the Upper Triassic to Lower Jurassic salt reflect its uneven original distribution. The seismically mapped individual salt structures such as tongues, sheets, and canopies might have originated from an autochthonous, “patchy” salt layer deposited in somewhat isolated half-grabens.
The offshore Essaouira Basin (Tafelney Plateau) segment of the salt basin displays various salt tectonic styles with mature allochthonous salt structures. The spectacular mid-Tertiary reactivation of salt tectonics in this segment is primarily attributed to the inversion associated with the Atlas mountain-building onshore. The ongoing compressional deformation, as the result of the Africa/Europe convergence, enhanced the steepness of the slope and is largely responsible for the ongoing salt movements. However, the basinward edge of the salt basin has dormant toe-thrust anticlines.
In the Agadir segment, the rapid influx of Tertiary sediments appears to be the dominant factor in the style of salt tectonics producing a wide diapiric domain underneath the slope. However, in this segment, the downdip edge of the salt basin is also clearly allochthonous. In general, the westernmost, leading edge of the salt deformational front with a well developed mid-Tertiary toe-thrust zone along most parts of the Moroccan salt basin offers world-class structural
traps for hydrocarbon exploration. Besides the toe-thrust anticlines, numerous salt-related play types were defined in the deepwater and remain largely untested to date.
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Haddou, J. and G. Tari, 2007, Subsalt exploration potential of the Moroccan salt basin: The Leading Edge, v. 26/11, p. 1454-1460. Hafid, M., 2000, Triassic-early Liassic extensional systems and their Tertiary inversion, Essaouira Basin (Morocco): Marine and Petroleum Geology, v. 17/1, p. 409-429. Rowan, M.G,, B.D. Trudgill, and J.C. Fiduk, 2000, Deep-water, salt-cored foldbelts: Lessons from the Mississippi Fan and Perdido foldbelts, northern Gulf of Mexico, in Atlantic Rifts and Continental Margins: Geophysical Monograph 115, American Geophysical Union, p. 173-191.
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