Aeromagnetic and gravity anomaly constraints for an early Paleozoic subduction system of Victoria Land, Antarctica

Abstract

In Victoria Land three fault-bounded tectonostratigraphic terranes are generally recognized: the Robertson Bay Terrane, the Bowers Terrane and the Wilson Terrane. Accretion and suturing of terranes at the East Antarctic Craton margin is usually related to west-dipping subduction during the early Paleozoic Ross Orogen: however, nature of subduction-related basement under the Bowers and Robertson Bay terranes is still debated and this adds uncertainty to existing tectonic models. This paper interprets aeromagnetic and gravity data against geologic and geochemical evidence to elaborate a new tectonic model for Victoria Land. We propose that the contrasting magnetic and gravity signatures over the northern and southern Bowers Terrane are linked to different basement rocks, specifically, buried oceanic basement beneath the northern Bowers Terrane and continental basement beneath the southern Bowers Terrane. The relevant linear magnetic anomaly in Central Victoria Land might also be a previously unrecognized suture within the Wilson Terrane.