Lewin, A and Meinhold, G and Hinderer, M and Dawit, EL and Bussert, B (2017) Provenance of sandstones in Ethiopia during Late Ordovician and Carboniferous-Permian Gondwana glaciations: petrography and geochemistry of the Enticho Sandstone and the Edaga Arbi Glacials. Sedimentary Geology. ISSN 0037-0738

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Abstract

We compare Ethiopian glaciogenic sandstone of the Late Ordovician and Carboniferous–Permian Gondwana glaciations petrographically and geochemically to provide insight into provenance, transport, and weathering characteristics. Although several studies deal with the glacial deposits in northern Africa and Arabia, the distribution of ice sheets and continent-wide glacier dynamics during the two glaciations remain unclear. Provenance data on Ethiopian Palaeozoic sedimentary rocks are scarce. The sandstones of the Late Ordovician glaciation are highly mature with an average quartz content of 95% and an average chemical index of alteration of 85, pointing to intense weathering and reworking prior to deposition. No evidence for sediment recycling was found. In contrast, the Carboniferous–Permian glaciogenic sandstones are less mature with an average quartz content of 75%, higher amounts of feldspar and rock fragments and a chemical index of alteration of 62. Trace and rare earth element concentrations indicate a higher input of juvenile material, most probably from proximal sources. Comparison with stratigraphically corresponding formations in Saudi Arabia shows similar geochemical patterns for the Upper Ordovician, but major differences in the Carboniferous–Permian. This supports previous assumptions of a large, uniform sediment dispersal system during the Late Ordovician glaciation, in which a combination of long transport paths and exceptionally strong weathering prior to the glaciation produced mature sandstone. During the Carboniferous–Permian, the glacial systems seem to have been more localised and glacial abrasion exposed fresh basement material.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://doi.org/10.1016/j.sedgeo.2017.10.006 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: Ethiopia, Palaeozoic, glacial sediments, geochemistry, petrography, maturity
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Depositing User: Symplectic
Date Deposited: 13 Oct 2017 14:10
Last Modified: 20 Oct 2017 09:54
URI: http://eprints.keele.ac.uk/id/eprint/4091

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