Tease Sandstone Fm

The type section occupies the southern and eastern rims of the Obosum Syncline and the type area for this exposure is in and around Tease village, where the strata dip up to 40° due in part to local faulting.

Synonym: Tease Fm

References: Annan-Yorke, 1971; Affaton et al., 1980; Blay, 1983; Carney et al., 2008; 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]

Consist of sandstone, medium- to coarse-grained, quartz-rich but with some feldspar. Hard and well cemented, with heavy mineral rich laminae in the foresets. Thin trough cross beds in herring-bone form are prominently developed. At the Tease Village, the sandstones are white and cross-laminated, and are feldspathic. Most are medium-grained and moderately well sorted, but there are also some very coarse/granule lenses and mud flakes. Some coarse, 'millet seed' grains occur, suggesting a local Aeolian influence during deposition (Carney et al., 2008). In the southern and eastern section is estimated to about 80-100m thick and around Tease the sandstone is a pale grey, well cemented, medium- to coarse-grained feldspathic quartz-arenite. Although the sandstone is generally well-sorted, there are lenses with coarse grains and granules of quartz; mud flakes are also present. Current directions measured from trough, tabular and herringbone cross-stratification is similar to those for the Ejura Sandstone Fm (Ejura Fm) (Carney et al., 2008). The exposure is estimated to be about 80-100m thick

Ediacaran Biota

late-Middle Ediacaran (uncertain of extent; arbitrary put as 75% to 90% up in regional extent of Bimbila Fm in the eastern part of Volta Basin)

Shallow marine (upper shoreface) sandstone deposited under the influence of high energy tidal waters (Carney et al., 2008). The Tease Sandstone Formation contains more unequivocal evidence for a nearshore marine, tidal influence in the presence of herringbone cross-bedding. Possibly these shallow water environments indicate a transient stage of sedimentation, reflecting a decrease in accommodation space towards the end of the marine fore-deep phase and before the basin-wide tectonism that ushered in the terrestrial molasse deposits of the Obosum Group (Carney et al., 2010). Paleocurrents trend towards the N and SW (Carney et al., 2008).