Shackleton Limestone archaeocyaths

Abstract

The Shackleton Limestone is a thick unit of bedded and allochthonous limestone, with minor dolostone, quartzite, sandstone and siltstone, spanning the central portion of the Transantarctic Mountains. It is a record of Early Cambrian shelf and peri-platform carbonate deposition on the margin of the East Antarctic craton. Slope, shallow marine and intertidal-supratidal conditions prevailed during deposition. Thirty-one species of archaeocyaths described from measured sections in the northern Holyoake Range (Nimrod Glacier area) and at Crackling Cwm (Byrd Glacier area) confirm earlier correlations of Shackleton Limestone faunas with the Botomian stage of Siberia. Archaeocyaths from a section at Mt Egerton (Byrd Glacier area) are of either Botomian or Toyonian age. Ten further archaeocyath species are added to the six species already known to be common to both Antarctica and Australia, confirming the existence of a Gondwana supercontinent in the Early Palaeozoic. New taxa described are the genera Kymbecyathus (Dokidocyathidae), Kiwicyathus (Irinaecyathidae), Sanarkophyllum (Erbocyathoidea, Gumbycyathidae fam. nov.), Clathrithalamus (Botomocyathidae) and Mawsonicoscinus (Coscinocyathina, Mawsonicoscinoidea superfam. nov., Mawsonicoscinidae fam. nov.), and the species Ladaecyathus jagoi, Tegerocyathella burgessi, Anaptyctocyathus manserghi, ?Veronicacyathus gravestocki and ?Pycnoidocyathus ecdemus.