Abstract

Early Paleozoic crustal deformation has been recognized along the paleo-Pacific margin of Gondwana, including southern Africa (Saldanian tectonism) and the Transantarctic Mountains of East Antarctica (Ross orogeny). Previously, no stratigraphic evidence for the Ross orogeny had been recognized within the Ellsworth Mountains of West Antarctica, believed to have been contiguous with the Transantarctic Mountains prior to the Mesozoic breakup of Gondwana. A disconformity between Middle to Upper Cambrian Heritage Group and Upper Cambrian to Devonian Crashsite Group strata indicates that the Ross orogeny did affect the Ellsworth Mountains, providing additional evidence that these rocks were once part of East Antarctica. Fluvial conglomerates overlying platform carbonates of the upper Heritage Group were derived, in part, from plutonic, volcanic, and metamorphic terranes in East Antarctica. Elsewhere in the Ellsworth Mountains, the disconformity is expressed by an abrupt change from shallow carbonate-platform deposits to siliciclastic shelf deposits. Similarities in lower Paleozoic stratigraphy between the Ellsworth Mountains, parts of the Pensacola Mountains (East Antarctica), and eastern South Africa imply that these regions were inboard of the zone of deformation that affected the proto-Pacific margin of Gondwana during the Ross orogeny and Saldanian, tectonism

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