Ross-age amalgamation of East and West Gondwana: evidence from the Shackleton range, East Antarctica

The structural setting of the northern Shackleton Range is dominated by west to south-west directed Ross-age thrusting leading to stacking of the following main units (I) remobilized northern basement, (II) ophiolite complex, (III-north) low-grade meta-sediments. The latter form a lithological link across the ice-covered centre (Fuchs Dome) to the southern Shackleton Range where similar lithologies occur in the south-westward transported Mt. Wegener nappe (III-south), which overrides unit (IV), a part of the East Antarctic Craton, consisting of the mid-Proterozoic basement of the Read Mountains plus an autochthonous Proterozoic sedimentary cover. Existing and new structural, petrological and geochronological data consistently support the interpretation of the Ross-age orogen in the Shackleton Range as a collisional belt formed by oblique sinistral collision of the East Antarctic Craton and the Kalahari Craton, and closure of an intervening oceanic basin (the traces in East Antarctica of the Mozambique Ocean?) through an initial NE-ward subduction. The formation of the collisional orogen in the Shackleton Range may be thus related to the final amalgamation of East and West Gondwana during late Precambrian-Cambrian time.