Abstract
THE Rokel River Group1–3 is a sequence of generally marine sediments and interbedded volcanic rocks which extends into Sierra Leone from Guinea as a NNE–SSW trending, northwards plunging synclinorium (Fig. 1). It is divided into six formations3 and rests unconformably on Archaean granitic basement. The Rokel River Group is considered to be late Precambrian to early Cambrian as it was folded and slightly metamorphosed near the present western outcrop margin, during the Rokelide orogeny3,4 around 550 Myr ago, the date of the Pan–African thermo–tectonic episode5. It is unconformably overlain by probable late Ordovician sediments of the Saionia Scarp Group1,6,7. We have studied the basal formation of the Rokel River Group, the Tabe Formation3, and describe here two members, the lower one exhibiting the characteristics of a glacial deposit. These glaciogenic sediments extend the known range of the Infracambrian–Eocambrian glaciation in West Africa.
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CULVER, S., WILLIAMS, H. & BULL, P. Infracambrian glaciogenic sediments from Sierra Leone. Nature 274, 49–51 (1978). https://doi.org/10.1038/274049a0
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DOI: https://doi.org/10.1038/274049a0
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