Sang Fm

The type area for the Sang Conglomerate Fm is the series of low hills to the west and south of Sang village, where topography suggests that it overlies the Bunya Sandstone. The type locality is exposed as roadside cuttings about 0.8km west of Sang town. The Sang Conglomerate and the similar conglomerates exposed farther west near Daboya.

Synonym: Sang Conglomerate Formation

[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]

It consists of massive, well-cemented cobble and pebble conglomerate is interbedded with green-grey lithic and feldspar-rich sandstone bearing pebbly layers and lenticles. Pebbles include quartz and quartzitic sandstone, together with ‘basement’ lithologies such as green metavolcanic rock, jasper, porphyritic dacite, garnetiferous psammite and various types of schist and phyllite. Clasts are locally closely packed, but mostly are supported within a dark grey, pink or purple, poorly sorted, coarse sand to granule grade matrix.

early-Late Ediacaran (equal durations given to Tamale Fm, Dunkro Fm and Sarg Fm in this Obosum Gr)

The Sang Conglomerate Fm represents high-energy fluvial channel deposits in rivers carrying molasse westwards, away from the orogen.