Evaporite fades and depositional environment of the Abu Dabbab Formation, Red Sea coast, Egypt

Abstract

The Abu Dabbab Formation is part of a Middle Miocene sedimentary sequence along the Red Sea Coast that is composed of evaporites with some clastic and carbonate intercalations. These rocks extend for hundreds of kilometres in variable thicknesses and are capped by a fractured and brecciated limestone with surficial calcareous crusts of caliche type. Detailed field and petrographical studies helped in establishing ten lithofacies types within the Abu Dabbab Formation, mainly evaporites with some dolostones along the upper part of the sequence. These lithofacies types represent different subenvironments probably indicative of a coastal tidal flat that was intermittently flooded by the sea, thus creating shallow brine-filled depressions or ponds. There is evidence of alterations in the evaporites brought about by diagenetic processes that were associated with changing environmental conditions. The diagenetic sequence could be subdivided into three stages: (1) a pre-burial early stage, (2) a burial stage and (3) an uplift late stage.