ABSTRACT

The Late Phanerozoic sequences of North Somalia can be divided into two parts. The pre-rift sediments of this area are documented by the Auradu, Taleh and Karkar Formations, which were deposited during late Maastrichtian–Eocene times. The Taleh Formation consists of massive gypsum- and anhydrite-layers, while marly limestones of the Karkar Formation were deposited in a restricted lagoonal to open shelf environment. While the Taleh Formation represents a regressive evolution, the Karkar Formation is generally transgressive. The Taleh Formation consists mainly of gypsum and anhydrite, alternating with marly horizons and well bedded limestones/dolostones. The Karkar Formation is made up of limestones marls and shales, containing a rich shallow marine fauna of Middle to Upper Eocene. Geochemical and petrographical investigations of the gypsum beds prove that they are mainly affected by a retrograde diagenesis, subrosion and gypsification. This is indicated by the occurrence of relictic anhydrite crystals in porphyrotopic gypsum individuals.