Palaeoevironmental significance of ichnogenus Diplocraterion torell from the Permian vryheid formation of the Karoo Supergroup, South Africa
Abstract The late Carboniferous to early Jurassic Karoo Supergroup of South Africa includes economically important coal deposits within the Vryheid Formation of Natal. The Karoo sediments are almost entirely lacking in body fossils but ichnofossils are locally abundant. Modern sedimentological and ichnofaunal studies suggest that the north-eastern part of the Karoo basin was marine. In this part of Natal a shallow basin margin accommodated a prograding fluvio-deltaic complex forming a broad sandy platform on which coal-bearing sediments were deposited. Ichnofossils include U-burrows (formerly Corophioides ) which are assigned to ichnogenus Diplocraterion . They are best compared with Diplocraterion polyupsilon (Smith, 1893) from Crawfurdland Burn, Scotland, and are better preserved than the Scottish specimens. Diplocraterion was made by suspension-feeding animals maintaining a constant depth relationship between the vertex of the U-burrow and the sediment—water interface, producing protrusive and retrusive forms of the burrow. They preferred subtidal and intertidal environments. Similar ichnofaunal associations from the Cretaceous of the mid-western United States and the Permian Sydney basin of southeastern Australia are unequivocably marine.