Expression of the Atlas Inversion Tectonics in Deepwater Offshore Morocco: Implications for Hydrocarbon Exploration

Gabor Tari¹, David Einarsson², Keith Louden³, and Wu Yue^4
1AllyGabor Geoscience, Bellaire, TX
²Geophysical Services Inc, Houston, TX
³Department of Oceanography, Dalhousie University, Halifax, NS, Canada
⁴Department of Earth Sciences, Dalhousie University, Halifax, NS, Canada

Neogene to Recent inversion of the Atlas system, the result of African-Eurasian plate convergence, is well documented onshore Morocco. However, recently acquired non-proprietary 2D reflection seismic data by GSI in the offshore Essaouira-Safi segment of the Atlantic passive margin of Morocco show the presence of inverted structures of mid-Tertiary age in the deepwater area as well.

These unusual structures are best imaged outboard of the widespread salt basin of Late Triassic/Early Jurassic age, some 200 km to the west from the coastline in water depth of 2000-4000 m. The anticlines have a general NW-SE/WNW-ESE trend and their growth can be dated by deepwater DSDP and exploration wells. Compressionally reactivated syn-rift normal faults are responsible for these inverted structures which clearly involved the pre-Mesozoic basement. The inverted structures represent an untested deepwater play type in the Atlantic region.

The areal extent of the inverted structures also coincides with the deepwater area which is inferred to have oceanic crust based on regional-scale potential field data. The new data set, however, shows very well developed syn-rift half-grabens with locally up to 2 km section in them. The seismic signature of these prominent syn-rift troughs is identical to those which were recently described on the conjugate Nova Scotia margin. This observation has important implications for the break-up history of the Central Atlantic, and also for deepwater exploration on both margins.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas