Detrital-zircon age-spectra for Late Archaean synorogenic basins of the Eastern Goldfields Superterrane, Western Australia

The Kalgoorlie, Gindalbie, Kurnalpi, Duketon and Burtville terranes were amalgamated by ∼2658 Ma into the Eastern Goldfields Superterrane, which was later accreted Cordilleran-style onto the foreland of a pre-existing continent. Late-stage (synorogenic) basins developed within the Eastern Goldfields Superterrane during the early stage of accretion. The basins are similar to all late-stage basins of Archaean provinces, developing late in the tectonic cycle in a strike-slip regime. They developed in two stages, during the gap in granite emplacement between ∼2658 Ma and ∼2648 Ma. Basin analysis suggests that the bulk of sediments was derived from rocks readily identifiable today within the superterrane, consistent with the provenance style of all late-stage basins. Sediment derivation from the foreland occurred only during Stage II, and is recorded only from basins proximal to the suture. Detrital-zircon geochronology has corroborated those interpretations. Eleven new SHRIMP U-Pb detrital-zircon datasets and 14 previously published datasets indicate that the bulk of zircon-bearing sediment was derived from the 2715 Ma to 2658 Ma High-Ca (TTG) granites and volcanic rocks that define the terranes. Moreover, primary modes in the detrital-zircon age-spectra of 2680 ± 3 Ma, 2673 ± Ma, 2666 ± 3 Ma and 2660 ± 3 Ma coincide with the peaks of emplacement of High-Ca granites. Provenance from across the suture has also been corroborated, with detrital-zircon age-spectra of the Kurrawang Basin, a Stage II basin close to the suture, having no match to rocks of the Eastern Goldfields Superterrane. Defining modes of ∼2730 Ma and >3000 Ma, some as old as ∼3750 Ma and ∼3540 Ma, can be matched to an ∼2735 Ma calc-alkaline volcanic province and quartzites with 4350-3130 Ma detrital zircon in the foreland. The study shows that detrital-zircon age-spectra can be powerful supporters of tectonic analysis, but for the study presented here their interpretation has been greatly assisted by prior basin analysis and a considerable geochronological database of source-rock equivalents.