Paleozoic tectonics of the Gondwana margin: Provenance of the Sperm Bluff Conglomerate. Implications for Cambrian tectonics and Devonian and younger paleotectonics and paleogeography

The basement rocks of eastern Northern Victoria Land (NVL) consist of a series of exotic terrances that were accreted to the Gondwanan margin while Andean style convergence was occurring. Conversely, Southern Victoria Land (SVL) shows little evidence of terrane accretion while undergoing convergence. The aim of this study was to test the possible extension of the tectonostratigraphic terranes of NVL into SVL and to enhance the understanding of the Cambro-Ordovician Ross Orogenic Belt, the controls on the early development of the Taylor Group (Beacon SuperGroup) basin and possible influences on the younger Victoria Land Basin. Fieldwork was carried out at five targeted sites (Mt Suess, Sperm Bluff, Gargoyle Turrets opposite Queer Mountain, the Wheeler Valley, a ridge above the Ringer Glacier and Repeater Ridge off Mt Cerberus) in SVL to study clast composition, relative abundances and sedimentology of the Devonian Sperm Bluff Conglomerate (Taylor Group, Beacon Supergroup) in the St Johns Range. Fieldwork consisted of clast counts to determine composition, measured sections to determine paleoenvironment, paleo-current analysis to determine source and sediment transport direction and sample collections (of both matrix and clasts). Representative samples were collected for petrology, geochemistry and geochronology.The conglomerate contains a range of pebble to cobble sized, meta-sedimentary vein quartz and volcanic clasts some of which are of lithologies not seen elsewhere in SVL. Representative samples were collected for petrology, geochemistry and geochronology. The results should provide a picture of the provenance and the depositional setting to assess whether belts of rock similar to the terranes of NVL lay to the east of the SVL basement. Determining the provenance of this unit would allow inferences to be made about the tectonic development of the SVL basin and its relationship to terrance accretion in NVL.