Hypautochthonous-allochthonous coal deposition in the Permian, South African, Witbank Basin No. 2 seam; a combined approach using sedimentology, coal petrology and palaeontology

A suite of techniques, including coal petrology, micropalynology, mesofossil analysis, and macroscopic appearance has been used to examine the Early Permian, South African, Witbank Basin No. 2 seam from a sample locality near Ogies. This coal appears to be similar in its palynological and petrographic composition to other coals of this interval from this basin. However, its accumulation appears to have been largely hypautochthonous or allochthonous evidenced by, erosive contacts, small scale cross-laminations, and fine lenticular bodies being recognised within the coal seam profile. This ex situ deposition probably, in part, relates to frequent wildfire activity, which may have promoted subsequent run-off and erosion, and led to the numerous mineral-rich horizons observed in the sample seam profile. In addition to the sedimentological characters described above, the petrology of the seam and its mesofossils, most particularly megaspores from a lycopsid parent vegetation, indicate saturated peat-forming conditions. However, examination of charred mesofossil fragments indicates periods of low humidity and even drying of the peat itself rendering it liable to combustion. These contradictory characters may indicate seasonality and suggest a coldness of the climate, at least for part of the year, that could account for the retardation of peat decay during these drier intervals. These characters can be reconciled with deposition during an interglacial phase as the Dwyka glaciation terminates, as has previously been proposed for the Witbank Basin No. 2 seam. (C) 2002 Elsevier Science B.V All rights reserved.