Shelf architectures of an isolated Late Cretaceous carbonate platform margin, Galala Mountains (Eastern Desert, Egypt)

An asymmetrical carbonate platform margin to basin transect has been invest igated in the Upper Campanian-Maastrichtian succession of the Galala Mounta ins, northern Egypt. Identification of systems tracts and their lateral cor relation was possible in slope sections only, whereas the monotonous chalk- marl alternations of the basinal sections could not be subdivided with resp ect to sequence stratigraphic terminology. The platform asymmetry is expressed by varying large-scale depositional arc hitectures exhibiting a rimmed platform with a sigmoidal slope curvature in south-easterly dip-sections and a ramp with a linear slope curvature in so uth-westerly dip-sections. The rimmed platform is subdivided into a gentle upper slope and a steep lower slope. The platform formed as a result of the initial topography that was controlled by the tectonic uplift of the North ern Galala/Wadi Araba Syrian Are structure. The calculated angles of the st eep lower slope of the rimmed part range from 5 to 8 degrees, whereas the r amp part has an angle of less than 0.1 degrees. (C) 2001 Elsevier Science B .V. All rights reserved.