Abstract

In Antarctica Devonian rocks accumulated in three separate areas that may have been intermittently connected.

Epicontinental sedimentation occurred on the consolidated margin of Gondwana in South Victoria Land, the Ohio Range and the Pensacola Mountains, and comprises the lower Beacon Supergroup (1400 m). Sequences of trace fossils in arenaceous sediments in South Victoria Land suggest littoral conditions during the Early Devonian, followed by a regression to alluvial plain deposition by the Late Devonian. A thin sequence of nearshore marine sediments with a shelly Malvinokaffric Emsian fauna occurs in the Ohio Range (50 m) and has been truncated by post-Devonian erosion. This sequence is an extension of the Pensacola basin in which thick and predominantly fluvial sedimentation occurred, with conditions becoming intermittently marine at the top.

Late Devonian magmatic are rocks with associated non-marine plant bearing sediments in Marie Byrd Land and North Victoria Land probably belonged to the same terrane on the outer margin of Gondwana during the Devonian.

The Crashsite Group (3000 m) of the Ellsworth Mountains forms part of a thick, folded lower Paleozoic sequence that, unlike the other sedimentary areas, indicates prolonged subsidence. Trace fossils and a local shelly fauna in the highest formation (300 m) suggest a marine connection with the Pensacola/Ohio basin during the Early Devonian. Volcanic fragments in the same formation may indicate that the Ellsworth basin lay between the epicontinental basins and the marginal magmatic are during the Devonian.