Authigenic titanite constraints on fast Mesoproterozoic basin formation in hot Antarctic crust

Geochronological data from detrital zircon, two generations of titanite, and authigenic sericite in glacial erratics transported to the Bunger Hills provide new insights into a deep subglacial basin in East Antarctica. Basin formation occurred during the late Mesoproterozoic, with diagenesis coinciding with granulite facies metamorphism in the underlying basement rocks. In line with previous studies, we interpret this basin to have formed as a rift sequence, but we extend this model by proposing that rifting was directly associated with Mesoproterozoic orogenesis, and that upper crustal extension was coupled with mid–lower-crustal ductile flow. The basin detritus was primarily sourced from a felsic magmatic-rich carapace emplaced at ca. 1180–1160 Ma. The authigenic mineralogy of the erratics, supported by chlorite thermometry and authigenic titanite geochronology, suggests that within the ensuing ca. 50–70 million years, the detritus was buried deeply and subjected to low-grade metamorphism (∼300 °C). Sericite ages complement the zircon and titanite dataset and reveal that the basin was largely unaffected by Cambrian tectonism, meaning that it was situated in thermomechanically stable crust and geographically distant to the major Gondwanan Indo–Australo–Antarctic suture. This study demonstrates the utility of coupled authigenic and detrital mineral geochronology in constraining sedimentary basin formation ages, and linking deep-crustal and near-surface processes.