Geometry and facies dynamics of Middle Jurassic carbonate ramp sandbodies, West-Central Portugal

Abstract

Abstract The Middle Jurassic succession of the Lusitanian Basin (Portugal) represents a carbonate ramp depositional system. For most of the time, the shallow-water facies defined a microtidal barrier-island complex, where prominent oolite-dominated sandbodies developed. Detailed facies analysis of these sandbodies allowed the recognition of their elementary depositional facies, which are described and whose relative importance is estimated. Sandbody geometry, hydrodynamic controls and ramp evolution are discussed. Carbonate sediment production and redistribution, coupled with inner ramp aggradational and progradational trends, have interacted in a such a way that ramp geometry persisted for a longer period of time than usually recorded in these systems.