Importance of thrust faulting in the tectonic development of northern Victoria Land, Antarctica

Abstract

The present configuration of Wilson Group, Bowers Supergroup and Robertson Bay Group in northern Victoria Land (Fig. 1) has been attributed to high-angle block-faulting^1–3 or more recently⁴ to major strike-slip faulting along the Lanterman and Leap Year Fault zones. In this latter interpretation⁴, adjacent units have allochthonous relationships and constitute separate geological terranes. We offer additional support for the concept of allochthonous terranes in northern Victoria Land but suggest here an alternative model to explain terrane juxtapositions. Our model emphasizes the role of thrust tectonics and implies severe structural telescoping of entire terranes with significant loss of intervening crust. We further suggest that this occurred during the Lower Palaeozoic Ross Orogeny in response to the collision of Antarctica with a westwardly directed eastern continental block. This requires that the northern Victoria Land segment of Gondwana was a zone of major plate convergence throughout the Cambrian–early Ordovician period.