Abstract

Sm–Nd isotopic and geochemical data from Neoproterozoic to Cambrian sedimentary rocks in the intracratonic eastern Officer Basin in central Australia highlight the evolving provenance roles of the basement complexes that underlie and bound the basin. Initial εNd values of around −12 for the basal units indicate that both were largely derived from the late Archaean to Mesoproterozoic Gawler Craton, which bounds the basin to the south. At c. 720 Ma an influx of juvenile, glacially derived sediment indicates partial uplift of the Mesoproterozoic Musgrave Block along the basin's northern margin, in a regime interpreted to be broadly extensional. At around 600 Ma, synchronous with the development of a foreland architecture, there was a large influx of Musgrave Block-derived sediments. This is interpreted to mark the onset of the intracratonic Petermann Orogeny, which was a long-lived event or series of events, spanning more than 70 Ma. Subsequent to c. 600 Ma, the Nd isotopic composition of sequences within the Officer Basin indicates an increasing contribution from the Gawler Craton despite up to 45 km of denudation of part of the Musgrave Block. This suggests that the majority of sediment derived from the Petermann Orogen bypassed the eastern Officer Basin for much of the history of the Petermann Orogeny.

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