Palynology of an Early Permian coal seam from the Karoo Supergroup of Botswana

Rock samples from Mmamantswe coalfield, Botswana are analysed for palynomorphs. The Mmamantswe microflora is Early Permian in age. Palynomorphs indicate a parent flora dominated by lycopods, sphenophytes and ferns. We correlate the Mmamantswe assemblage to other Gondwanan palynofloras. Ecca-equivalent lithologies in Botswana and South Africa may be diachronous. Two borehole cores from the south-east area of the Mmamantswe coalfield (Mmamabula area), Botswana, provided 124 samples for palynological analysis. The assemblage is dominated by trilete and alete spores, indicating a parent flora of mostly lower order lycopods, sphenophytes and ferns. Distinctive taxa at Mmamantswe include Brevitriletes levis, Cannanoropollis densus, Gondisporites raniganjensis, Platysaccus radialis, Scheuringipollenites ovatus, and Verrucosisporites naumovae. Saccate pollen is less common, suggesting the assemblage reflects the local vegetation of the coal swamp. The Mmamantswe microflora has been sub-divided into two assemblage zones, with the lower Assemblage Zone 1 correlating with Assemblage Zone 1 of Anderson (northern Karoo Basin, South Africa), Biozone B of the Waterberg (South Africa) and the Milorgfjella assemblage (Dronning Maud Land, Antarctica). The upper Assemblage Zone 2 of Mmamantswe is correlated with Assemblage Zone 2 of Anderson (northern Karoo Basin, South Africa), Biozone C of the Waterberg (South Africa), and the No. 2 Seam assemblage (Witbank coalfield, South Africa). On the basis of these correlations the Mmamantswe microfloral assemblage is assigned to the Asselian, Sakmarian and Early Artinskian periods.