Low-grade Sandow Group metasediments of the Denman Glacier area (East Antarctica): Chemical composition, age and provenance from U-Pb detrital zircon data, with some palaeotectonic implications

The Sandow Group in the Denman Glacier area consists of low-grade supracrustal (post-cratonic) strata. Such rocks are scarce and poorly studied in East Antarctica, but are significant for a better understanding of the geological history and tectonic evolution of the Precambrian supercontinents. We report U-Pb (LA-ICP-MS) detrital zircon ages which mostly fall into two groups of ca 1350 900 Ma and ca 1800 1500 Ma, which correspond to those of crystalline rocks exposed in the western Australo-Antarctica. The youngest zircons with magmatic zoning yield ages of ca 950-900 Ma which define the maximum age of sedimentation. Chemical and neodymium isotopic compositions of the Sandow Group rocks indicate derivation from a Proterozoic largely granitic source region. High-Ti mafic volcanic activity accompanied sedimentation, and therefore the Sandow Group should be considered a volcanic-sedimentary succession. The Sandow Group was presumably accumulated in a continental (pull-apart?) basin formed in the Neoproterozoic in relation to proto-Darling Fault system activity with its continuation into Antarctica. The Sandow Group may have its correlatives in Western Australia where sedimentary successions (e.g., Moora and Badgeradda Groups) occur along the proto-Darling Fault system.