Lower and Middle Jurassic platforms and ramps from the High Atlas of Morocco

The Central High Atlas of Morocco offers exceptional outcrop exposures of Jurassic carbonate platforms. Extensively studied in terms of geometry, facies, biostratigraphy and sequence stratigraphy, the two examples illustrated in this field guide provide key information relative to facies and geometry of Jurassic carbonate systems developed in extensional basins during rift to post-rift extensional phases. Both outcrops display several km-scale, structurally intact and fully accessible transects from platform to basin that provide highly valuable analogues for facies character, architecture and depositional geometries at reservoir and seismic scales, which are highly relevant for academic investigations and hydrocarbon exploration and production. The Djebel Bou Dahar (DBD) is a Lower Jurassic high-relief carbonate platform with steep slopes that developed on the footwall of a rotating fault block in a half-graben. The DBD field excursions offer the opportunity to visit: 1) well-exposed and fully accessible platform to slope transects, which can provide highly valuable information about outer platform, margin and slope lithofacies character and distribution; and 2) outstanding outcrops exposing a complete N-S oriented transect through the carbonate stratigraphy that allows the reconstruction of its evolution through time. The Amellago ramp (AR) outcrop exposes a 37 km-long transect of Toarcian to Aalenian (Lower to Middle Jurassic) low-angle prograding carbonate ramp rich in ooids, with gradual facies changes from supratidal carbonates to offshore marls in the basin. The AR field excursions provide one of the rare examples whereby a large-scale ooidal ramp can be continuously examined in great detail, providing an analogue for a range of ooidal reservoirs associated with post-rift thermal subsidence.