Sedimentological Features of the Bathan Formation (Miocene?) North of Sharm Ubhur, Jeddah Region, Saudi Arabia PDF

Keywords

sedimentology, Jeddah, Saudi Arabia

Abstract

Two vertical sections were made in the Tertiary coastal hills near Jeddah. Their lithology was studied and sediment samples were taken concurrently for grain size and mineralogical analyses. Their depositional environments, paleogeography and source rocks, deduced from their sedimentological, mineralogical and petrological characteristics are discussed herein. The sequences represent alluvial terraces and fan deposits typical of debris flows. They are comprised of poorly sorted, subrounded to rounded pebbles and cobbles embedded in a coarse-grained sand and clay matrix with generally inclined planar bedding. They were probably laid down in a braided-stream environment and may represent alluvial deposits of a proto-Wadi Fatima. The alluvial recorded is characterized by drainage lines generally active enough to cut the basement rocks as indicated by high epidote content. These hills document the uplift of a Red Sea Escarpment considerably after deposition of the Jizan group. Repeated cyclic variation with a dominant regressive phase and a period of non-deposition interrupted by volcanism probably indicates a post Oligocene drainage system.