The Cambrian Araba Formation in northeastern Egypt: Facies and depositional environments

The Cambrian Araba Formation exposed in Gabal El Zeit and in the Sinai Peninsula unconformably overlies Precambrian basement rocks, and is in turn overlain unconformably by the Ordovician Naqus formation. The Araba Formation has been subdivided into three informal lithologic units: lower, middle and upper, from field observations. Seven sedimentary facies assignable to three facies associations (fluvial, tidal and coastal to open marine) are recognized within the Araba Formation. The lower unit comprises two main facies: matrix-supported conglomerate (facies-A) in the south (Gabal Araba and Wadi Feiran) and interbeds of granulestone and sandstone (facies-B) in the north (Gabal Dhalal and Taba) deposited in fluvial conditions. The middle unit includes four facies: cross-bedded sandstone (facies-C), thin laminated sandstone (facies-D), burrowed-massive sandstone (facies-E) and rhythmically bedded sandstone–mudstone (facies-F) deposited mainly under tidal conditions in the coastal zone. The upper unit consists mainly of interbeds of burrowed mudstone-siltstone, with Skolithos, probably deposited in open marine environment. The sequence records the southward transgression of the Tethys Ocean over a horst and graben system developed in the late Precambrian on the northern margin of the Arabo-Nubian continent.