Detrital-zircon age spectra have been determined for sedimentary rocks from the Delamerian orogen, southern Australia. In Neoproterozoic sedimentary rocks, patterns progressively change from Mesoproterozoic-to Neoproterozoic-dominated detritus and there are few zircons that are close to the depositional age. The base of the Cambrian Kanmantoo Group marks an abrupt change in provenance to detrital patterns dominated by Ross and Delamerian (600-500 Ma) and Grenvillean ages (1200-1000 Ma). These patterns are strikingly similar to those obtained from Lachlan fold belt sedimentary rocks, indicating that the sedimentation recorded in the Kanmantoo Group marks a change from deposition of sediments derived from the Australian cratons to those representative of the early Paleozoic Gondwana mudpile. If sedimentary rocks with zircon-provenance characteristics such as those of the Kanmantoo rocks extend under elements of the Lachlan fold belt, they would provide suitable protoliths for the S-type granites of southeastern Australia. Data Repository item 9828 contains additional material related to this article.

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Ion microprobe dating of zircon and monazite from high-grade gneisses has been used to (1) determine the timing of metamorphism in the Western Province of New Zealand, and (2) constrain the age of the protoliths from which the metamorphic rocks were derived. The Western Province comprises Westland, where mainly upper crustal rocks are exposed, and Fiordland, where middle to lower crustal levels crop out. In Westland, the oldest recognisable metamorphic event occurred at 360-370 Ma, penecontemporaneously with intrusion of the mid-Palaeozoic Karamea Batholith (c. 375 Ma). Metamorphism took place under low-pressure/high-temperature conditions, resulting in upper-amphibolite sillimanite-grade metamorphism of Lower Palaeozoic pelites (Greenland Group). Orthogneisses of younger (Cretaceous) age formed during emplacement of the Rahu Suite granite intrusives (c. 110 Ma) and were derived from protoliths including Cretaceous Separation Point suite and Devonian Karamea suite granites. In Fiordland, high-grade paragneisses with Greenland Group zircon age patterns were metamorphosed (M1) to sillimanite grade at 360 Ma. Concomitant with crustal thickening and further granite emplacement, M1 mineral assemblages were overprinted by higher-pressure kyanite-grade metamorphism (M2) at 330 Ma. It remains unclear whether the M2 event in Fiordland was primarily due to tectonic burial, as suggested by regional recumbent isoclinal folding, or whether it was due to magmatic loading, in keeping with the significant volumes of granite magma intruded at higher structural levels in the formerly contiguous Westland region. Metamorphism in Fiordland accompanied and outlasted emplacement of the Western Fiordland Orthogneiss (WFO) at 110-125 Ma. The WFO equilibrated under granulite facies conditions, whereas cover rocks underwent more limited recrystallization except for high-strain shear zones where conditions of lower to middle amphibolite facies were met. The juxtaposition of Palaeozoic kyanite-grade rocks against Cretaceous WFO granulites resulted from late Mesozoic extensional deformation and development of metamorphic core complexes in the Western Province.