The age distributions of four detrital zircon samples from Western Australia placer deposits are found to be dominated by Neoproterozoic and Mesoproterozic ages; this outcome challenges a long-held assumption about derivation from the nearby Archean Yilgarn craton. The dominant ages are consistent with derivation from Proterozoic orogens marginal to the Yilgarn craton, including the Pinjarra orogen and Leeuwin block to the west and the Albany-Fraser orogen to the south. The results suggest that these marginal orogens were preferentially uplifted in the Jurassic-Cretaceous rifting event that formed the Perth basin and subsequently dominated the sedimentary contribution to this basin. These sediments have since been recycled to form the modern beach-sand placer deposits that reflect their non-Archean provenance despite proximity to the Yilgarn craton. The lack of a sedimentary contribution from the Yilgarn craton to the Perth basin implies that peneplanation was complete before the Mesozoic and that denudation rates have been minimal ever since.