Lower Karroo pollen and spore assemblages from the coal measures and underlying sediments of the Siankondobo coalfield, Mid‐Zambezi valley, Zambia

Abstract

A palynological investigation of three boreholes in the Lower Karroo of the Kazinze area of the Siankondobo coalfield (GS 31, 35 and 36), has indicated pollen and spore assemblages in the coal measures and underlying arenaceous beds. The arenaceous sediments occuring at the bottom of the Karroo succession, are part of the Siankondobo Sandstone Formation. They are relatively unfossiliferous, although rare thin mudstone intercalations found in one of the boreholes (GS 36), contain assemblages dominated by monosaccate forms (Cannanoropollis obscurus and Plicatipollenites indicus). The Gwernbe Coal Formation, (Ecca series), which rests unconformably on the Siankondobo Sandstone Formation contains at its base a dominantly arenaceous member (Maamba Sandstone), and in one of the boreholes (GS 31) carbonaceous shale intercalations contain mainly trilete spores e.g. Punctatisporites gretensis, Acanthotriletes filiformis and Apiculatisporis levis. Overlying the Maamba Sandstone is a coal seam (Main Seam), which in turn is overlain by carbonaceous mudstones with thin coal seams. The Main Seam and the carbonaceous mudstones, are generally dominated by trilete and striate and non‐striate disaccate forms e.g. Punctatisporites gretensis, Acanthotriletes filiformis, A. tereteangulatus, Apiculatisporis levis, Leioiriletes directus, Protohaploxypinus limpidus, P. goraiensis, Vesicaspora ovala and V. potoniei; one notable exception to this is the upper part of GS 31 where Incertae sedis forms are the most common. The information obtained from the three wells suggests that three concurrent range zones can be recognized and a tentative zonation has been proposed. The Siankondobo coalfield assemblages show many similarities to those recorded from the lower and upper part of the Luwumbu Coal Formation some 1,000 kilometers to the north‐east, in the north Luangwa Valley of Zambia. Common to both areas is the high proportion of monosaccates in the beds underlying the carbonaceous sediments, followed by a general dominance of triletes and disaccates (striate and non‐striate) throughout most of the carbonaceous sediments, although dominance of triletes does occur in some instances in the lowermost carbonaceous beds.