A relatively brief ice age in the Late Ordovician, about 445 Ma ago, when North Africa was located near the South Pole led to the deposition of terrestrial and marine glacial sediments across northern Africa (e.g. Le Heron & Craig 2008). Several types of glacial landforms have been identified previously in these glacial rocks, including sedimentary features interpreted as ice-proximal fans and tunnel valleys produced by subglacial meltwater flow (e.g. Hirst 2012). These glacigenic rocks had been buried beneath about 2000 m of overlying sediment and have been deformed subsequently by multiple orogenic phases. A number of asymmetrical depocentres have been identified in three-dimensional (3D) reflection-seismic records from Illizi Basin, Algeria (Fig. 1). They are interpreted as grounding-zone wedges (GZWs), by analogy with similar features in Quaternary sediments on the Greenland margin (Dowdeswell & Fugelli 2012).