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Stratal and Facies Anatomy of a Lower Jurassic High-rising Carbonate Platform (Jebel Bou Dhar, High Atlas, Morocco), Part 2: Static Modeling

Erwin W. Adams1, Klaas Verwer2, Jeroen A.M. Kenter2, and Cathy Hollis1
1 Carbonate Team, Shell International E&P, Rijswijk, Netherlands
2 Faculty of Earth and Life Science, Sedimentology and Marine Geology, Vrije Universiteit, Amsterdam, Netherlands

A GIS based geologic dataset was build of a Lower Jurassic carbonate platform outcrop (Jebel Bou Dahar, High Atlas, Morocco). The carbonate platform developed on a structural high in an active rift basin and exhibits a high relief and aggradational to backstepping margin style. The study window is located some 200 m away from the physical platform break and an extensive fault system (probably syn-depositional fissures) crosscuts the study window. Syndepositional gravitational collapse of the aggrading platform margin likely occurred and modified the depositional margin, as documented by platform interior sediments being in direct contact with onlapping slope deposits. The platform drowned during the late Pliensbachian to early Toarcian. The excellent outcrop conditions allowed comprehensive documentation of a platform interior study window (aerial coverage of about 1 km2 with present -day canyons cutting 30 m deep into the platform) with digital surveying technologies (DGPS and LIDAR) determining the spatial variation and quantitatively characterizing the 3 -D stratal and facies architecture. This paper presents preliminary results of the methodological principles used to model this platform interior study window comprising about 14 shoaling cycles of subtidal lagoon sediments grading into inter - and supratidal tidal flat and sandbar deposits. We especially report on modeling and characterizing the distribution of sandbar shoal facies. A semi-quantitative approach was used to characterize and link petrophysical characteristics to the mapped depositional facies. Ultimately this digital outcrop model will serve as input in dynamic reservoir simulation models.