Provenance of Ordovician–Silurian and Carboniferous–Permian glaciogenic successions in Ethiopia revealed by detrital zircon U–Pb geochronology

Palaeozoic sedimentary successions in northern Ethiopia contain evidence for two Gondwana glaciations during the Late Ordovician and Carboniferous–Permian. We compare sediments of the two glaciations regarding their detrital zircon U–Pb ages. The main age group for both formations is Pan-African (c. 550–700 Ma). However, the remaining spectra are different: The Upper Ordovician–Lower Silurian Enticho Sandstone is characterised by a Stenian–Tonian (c. 1 Ga) zircon population. The Carboniferous– Permian Edaga Arbi Glacials contain a prominent c. 800 Ma population. The Stenian–Tonian zircons are likely derived from the centre of the East African Orogen and were supplied via the Gondwana super-fan system. This material was transported by the Late Ordovician glaciers and formed the Enticho Sandstone. Tonian (c. 800 Ma) zircons are abundant in the Ethiopian basement and represent the earliest formation stage of the southern Arabian–Nubian Shield. Glaciers of the Late Palaeozoic Ice Age must have cut deeply into the basement for efficient erosion. No recycling of the Enticho Sandstone by the Edaga Arbi Glacials took place on a grand scale — probably because sedimentation of the former was limited to northern Ethiopia, whereas the source area for the latter was to the south.