Stratal and Facies Anatomy of a Lower Jurassic High-Rising Carbonate Platform (Jebel Bou Dhar, High Atlas, Morocco) – Part 1: Digital Outcrop Model

K. Verwer¹, J.A.M. Kenter¹, E. W. Adams², G. Della Porta³, and O. Merino-Tomé^4
1 Vrije Universiteit, Amsterdam, Netherlands
² SIEP Carbonate Team, Rijswijk, Netherlands
³ Cardiff University, Cardiff, United Kingdom
⁴ Universidad de Salamanca, Salamanca, Spain

Studies integrating high-resolution 3D lithofacies distributions and stratal geometries in carbonate platforms are uncommon because of scarcity of 3D continuous outcrops. A continuous carbonate-platform outcrop (High Atlas, Morocco) provided those conditions and was analyzed using DGPS and LIDAR imaging. The Lower Jurassic Jebel Bou Dahar (JBD) evolved in a rift basin, developed into a flat-topped, high-relief, carbonate platform during the Sinemurian to Pliensbachian and drowned in the lowermost Toarcian. It measures roughly 35 by 4-5 km and shows a backstepping margin with completely exposed platform, margin, flank and basin. Next to reconstruction of the evolution style of the platform, this study focuses on two study windows in which high-resolution digital mapping was applied: a platform interior- and lower slope window (both areas cover about 1 km2 and are 30-50 m in depth). The platform study box is located ~200 m away from the platform break, and exposes ~14 shoaling subtidal lagoon to inter- and supratidal tidal flat and sandbar cycles with frequent subaerial exposure. The slope study box provides access to a lower slope succession (ca 350 to 500 meter of water depth) bordering a self-eroding margin, with discontinuous boulders sheets and alternating thin-bedded turbidites and marls. This project aims to provide precise and accurate information on sedimentary bodies and their bedding geometries. It seeks methodological principles to populate geological models and the resulting GIS model will integrate all spatial and geological data, and allows geostatistical analyses for depositional models, sequence stratigraphy, prediction from seismic reflection data, and flow models for hydrocarbon reservoirs.