Channelized sandstone bodies (‘cordons’) in the Tassili N'Ajjer (Algeria & Libya): snapshots of a Late Ordovician proglacial outwash plain

A Late Ordovician proglacial outwash plain, preserved in the UNESCO World Heritage Site of Tassili n'Ajjer (Algeria & Libya), reveals fossilized networks of braided and anastomosed channels formed by high-magnitude flood events. These channelized sandstone bodies, or 'cordons,' exhibit ribbon-like forms with widths ranging from 60 to 600 meters and thicknesses from 5 to 30 meters, offering a unique snapshot of an unconfined outwash braidplain. The study combines satellite imagery, sedimentary logs, and photomosaics to analyze the architecture and facies of these features, which indicate they were deposited during glacier outbursts within a sand-dominated deltaic topset succession.

Girard, F., Ghienne, J.-F., & Rubino, J.-L. (2012). Channelized sandstone bodies (‘cordons’) in the Tassili N’Ajjer (Algeria & Libya): snapshots of a Late Ordovician proglacial outwash plain. Geological Society, London, Special Publications, 368(1), 355–379. https://doi.org/10.1144/sp368.3