Abstract
The Triassic sequence consists of an expanse of interdigitating siliciclastic and carbonate rocks with evaporites. Eight sedimentary facies are recognized. The Lower Triassic Sudair facies represents a widespread regression when Upper Permian marine conditions gave way to a shallow marine shelf and fine clastic deposition in the Lower Triassic. Middle Triassic rocks (mostly non-marine sandstone and shales) in the S area pass into mixed siliciclastic and carbonate continental facies with intermittent emergence and near-shore conditions. The Upper Triassic Minjur facies of thick siliciclastics, developed in a non-marine environment with intermittent emergence in the N.