The Late Cretaceous Ceduna Delta is the largest deltaic system on the Australian continent, yet its source is unknown. Apatite fission-track data reveal widespread Late Cretaceous exhumation across the southern Australian margin. New detrital zircon analysis of 786 grains from the Gnarlyknots-1 well, which penetrated the offshore delta top, show that the upper part of the delta (Santonian–Maastrichtian) was sourced largely from recycled Permian to Early Cretaceous cover and underlying basement eroded from the margin, proximal to the basin. This challenges the widely accepted model involving distal provenance of >2000 km from the eastern margin of Australia.

Supplementary material

The 2D seismic reflection data, results for detrital zircon LA-ICP-MS and zircon fission-track analyses, including the LA-ICP-MS method, and a list of sample intervals and ages are available at www.geolsoc.org.uk/SUP18582.

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