Damongo Fm

The type locality is exposed around the Damongo area (Carney et al., 2010). Lower-middle formation of the Kwahu Gr.

Synonym: Lower Voltaian (Annan-Yorke, 1971; Blay, 1983).

References: Mason, 1963; 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]

The Damongo Fm shows rapid alternations between flaggy, fine to medium-grained, micaceous, quartzose or feldspathic sandstones and micaceous siltstones, exemplified in the type area around Damongo. Sedimentary features include mudflakes, trough and tabular cross-bedding, cross-lamination and structures resembling hummocky cross-stratification; northerly directed paleocurrent flows are dominant (Carney et al., 2010). In the south, the formation is considered a lateral equivalent of the Agogo Clay Gall Sandstone of Mason (1963), due to common occurrence of ripple marks, mud flakes and mud cracks.

Early Tonian. The 6 formations of Kwahu Gr - upward succession of Yabraso Fm (Yabraso Sandstone Formation), followed by the Damongo Formation, Mpraeso Fm (Mpraeso Sandstone Formation), Abetifi Fm (Abetifi Sandstone Formation), Obocha Fm (Obocha Sandstone Formation) and Anyaboni Fm (Anyaboni Sandstone Fm) - are arbitrarily given equal durations (5% of Tonian span; from 0 to 30% up in Tonian).

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