Critical Remarks on a postulated Genetic Relationship between Precambrian Thucholite and Boghead Coal

Coal-Bearing Depositional Systems

“…This restriction renders them unsuitable for large-scale coal formation and thus only algal coals (boghead coals or torbanites) and oil shales are known from pre-Silurian periods. Among these are Precambrian torbanites of anthracite rank in North America, the thucholite deposits of the Witwatersrand (Snyman 1965;Hoefs and Schidlowski 1967;Schidlowski 1968;Plumstead 1969;Hallbauer and van Warmelo 1974;Hallbauer 1975), numerous occurrences of graphite schists in Australia and elsewhere and the Kukersite deposits of Silurian age which are mined and utilised in Estonia. The latter have been formed mainly from one alga, Gloeoeapsomorpha prise a, so named because of its similarity with the Recent Cyanophyta genus Gloeoeapsa.…”

Geology and recognition criteria for uranium deposits of the quartz-pebble conglomerate type. Final report

“…A number of techniques have been applied in determining the structural attributes of Witwatersrand carbon. Several investigators have employed standard coal petrographic techniques, using reflected light microscopy (Snyman, 1965;Schidlowski, 1969). Starting in the mid-1970s, other investigators have ashed the carbon by combustion in a furnace at 500°C.…”

“…The higher reflectivity is due to the radioactive bombardment of the carbon. Snyman (1965) and Schidlowski (1969) both noted "flow structures" in the carbon. Flow in a plastic state is Indicated -266-I t by several features, including linear concentrations of small inclusions (with elongate inclusions drawn out in this direction) and "streamline" and pressure shadow effects around relatively non-compressible grains included in the carbon.…”

“…Fibrous "thucholite" seam at the base of a typical Witwatersrand conglomerate (from Schidlowskl, 1969). Schidlowski (1969) showed that the supposed resemblance of Witwatersrand carbon to sapropelic coal was a fortuitous one. In the coal, the long axes of deformed (flattened) algae are roughly parallel to bedding, while in the carbon, the supposedly similar structures (Figure 71.5) are due to the lensshaped cross sections of carbon "fibres" which are usually perpendicular to bedding.…”

“…74. Fibrous "thucholite" seam at the base of a typical Witwatersrand conglomerate (from Schidlowski, 1969).…”