Facies pattern of the Sidi Aïch Formation: Reconstruction of Barremian paleogeography of Central North Africa

Abstract

A detailed facies analysis of the Sidi Aïch Formation has been carried out to give insight into the depositional environments with a view to work out the Barremian paleogeography of the Central North Africa (western Libya, Tunisia, and central to eastern Algeria). Altogether seventeen facies were identified. Over the major part of the area Sidi Aïch Formation is represented dominantly by varieties of sandstone which grades upward into fine-grained rock groups. Towards the South, near paleohighs and the zone of Chotts (Chott El Jerid, Chott El Gharsa and chott Melrhir), coarse-grained sand and gravel deposits are present in this succession. Limestone, paleosol and coal are also present as minor constituents. The depositional environments grade from alluvial deposits near sources (Hoggar shield) in southern Algeria and paleohighs, fluvial to lacustrine in both Central Tunisia and Central Algeria with a gradually increase in deltaic influence towards the former, to marine deposits towards troughs in the North. The basin was probably wide, shallow, with a gentle slope to the North and drained by the perennial system of large-scale and low-sinuosity braided rivers. The paleoclimate was semi-arid and the aridity gradually increased with time.