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

Abstract

Paleozoic sedimentary successions in northern Ethiopia contain evidence for two Gondwana glaciations during the Late Ordovician and Carboniferous–Permian. We compare the sediments of the two glaciations with respect to their detrital zircon U–Pb ages. The main age group for both formations is Pan-African (c. 700–550 Ma). However, the remaining spectra are different. The Upper Ordovician–Lower Silurian Enticho Sandstone is characterized 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 probably 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 Paleozoic 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 the sedimentation of the former was limited to northern Ethiopia, whereas the source area for the latter was to the south. Supplementary material: Laser ablation ICP-MS operation parameters and results are available at https://doi.org/10.6084/m9.figshare.c.4605548