Devonian of Antarctica

Abstract The Devonian System of Antarctica is part of a succession of sedimentary strata belonging to what is loosely termed “Beacon rocks”. Beacon usually connotes flat-lying or gently-dipping strata exposed along the Transantarctic Mountains of East Antarctica and spanning the Upper Palaeozoic and the Lower Mesozoic. The first indication of Devonian age was the discovery of freshwater fish remains at Granite Harbor in the lower sandstones of the Beacon. During the International Geophysical Year, more fish remains, assigned to the Upper or Middle Devonian, were collected from central Victoria Land, and Lower Devonian terebratuloid brachiopods were discovered in the Horlick Formation of the Ohio Range. Further collections from the Horlick Formation revealed a marine faunal assemblage of brachiopods, bryozoans, gastropods, pelecypods, tentaculitids, trilobites, and fish remains. The brachiopods include Orbiculoidea falklandensis, Orbiculoidea cf. bainii, Lingula spp., Tanerhynchia doumanii, Australospirifer cf. iheringi, Pleurothyrella antarctica, and Cryptonella? sp. Of these, Australospirifer and Pleurothyrella indicate Malvinokaffric provincial ties; Tanerhynchia indicates probable communication between Antarctica and New Zealand. Fish and psilophytic plants are also associated with this fauna. These fossils occur in a thin sequence of sandstone and shale with a maximum thickness of 50 metres, overlying the granitic basement rocks and underlying Permian? tillites. Along the Transantarctic Mountains and elsewhere in East Antarctica, flat-lying rocks occur in sequences similar to those of Victoria Land and the Horlick Mountains but, due to the lack of fossil evidence, correlation must be established by physical stratigraphy. Devonian rocks occur also in the Ellsworth Mountains of West Antarctica. Unlike that of East Antarctica, the sequence in West Antarctica is intensely folded, but a Devonian faunule, including Orbiculoidea falklandensis, occurs in the Crashsite Quartzite, which is correlative with the Lower Devonian fauna of the Horlick Formation..