Ejura Sandstone Fm

Synonym: Ejura Fm

References: Annan-Yorke, 1971; Affaton et al., 1980; Blay, 1983; Carney et al., 2010

[Fig. 1. Geological map of the Volta Basin and surroundings, after Sougy (1970) and Affaton et al. (1980)]

[Fig. 2. Schematic lithostratigraphic sections showing principal lithologies and inferred correlations between Kwahu and Bombouaka group units across the Volta Basin.]

[Table 1. Published stratigraphic data available for Voltaian deposits]

[Table 2. Proposed lithostratigraphic scheme (left-hand column) compared with previous nomenclature.]

[Fig. 3. Synthetic lithologic section of the Volta Basin sedimentary infilling]

Consists of sandstones which have very mature quartzite, showing channels and possible symmetric, standing wave-ripples. It is a pale grey to cream, medium- to locally coarse-grained quartzite showing tabular, thin to medium bedding with some trough cross-stratification. Locally, bed-tops contain large-wavelength, slightly asymmetrical ripple-like features. These are not cross-laminated internally, but draped by successive sandstone beds of approximately equal thickness. The bases of some beds are erosional; hummocky, down-lapping bedforms are also locally present. Elsewhere on the outcrop, similar quartz-rich sandstones are commonly gritty with moderate sorting in thin to very thin and tabular to weakly lenticular beds. These have wavy form in places and trough cross-bedding is developed locally and having about 80-100m in thickness.