Trace Fossils and Pseudofossils from the Proterozoic Cuddapah Supergroup

摘要

Only three ichnoforms are recorded from the Guddapah Supergroup so far. Two of them were described from the Gulcheru Quartzite without specific determination, while the third, identified as Planolites sp. was discovered near Nagarjuna Sagar. The claim that the so called horizontal burrows from the Gulcheru Quartzite resemble ichnogenus Arthrophycus is incorrect, as in reality they are trace fossils of 'inorganic origin', referable to the forms Rhysonetron or Manchuriophycus. Also, the pock marks constituting 'vertical and inclined burrows' from the Gulcheru Quartzite are, in fact, a weathering feature. Hence, the opinion that these 'trace fossils' are useful for local correlation is not tenable. Planolites sp. reported from the Nagarjuna Sagar area is now identified under the specific name P. beverleyensis (Billings). The sandstone sequence yielding Planolites sp. was traditionally believed to be a part of the Srisailam Formation. There was a suggestion that it may be considered as belonging to the Banganapalle Sandstone of Kurnool Group, in view of the occurrence of Planolites sp. and intercalations of shales and limestones. Since the sediments in question are not laterally continuous with any outcrop of the Kurnool Group, it is suggested here that it be recognised as a separate lithostratigraphic entity and correlated with Banganapalle Sandstone.