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The southeastern Georgetown Inlier (Greenvale Province) consists of Early Palaeozoic metamorphic rocks in fault contact along the Lynd Mylonite Zone with the Palaeoproterozoic to Mesoproterozoic craton of northeastern Australia. It has a central assemblage of metamorphosed silicic volcanic and sedimentary rocks considered equivalent to the Late Cambrian to Early Ordovician Seventy Mile Range Group that developed in an extensional backarc in the Charters Towers Province to the southeast. In the western part of the Greenvale Province, the Oasis Metamorphics have a U - Pb zircon SHRIMP metamorphic age of 476 ± 5 Ma and are intruded by the granodioritic Lynwater Complex with U - Pb zircon ages of 486 ± 5 Ma and 477 ± 6 Ma. These ages are consistent with these rocks forming basement and intrusive equivalents to the extensional volcanic basin. Existing geochronological constraints on the Halls Reward domain, located at the eastern margin of the province, are consistent with it being basement to the extensional basin. Several domains are recognised in the Greenvale Province with either dominantly steep or low to moderate dips of the main foliation, and each experienced multiple deformation with locally up to four overprinting structural phases. Steepening of foliation in several of the domains is attributed to contractional deformation in the Early Silurian that is inferred to have overprinted low-angle foliation developed during extensional tectonics in the backarc setting. Contractional deformation related to the Early Silurian Benambran Orogeny is considered responsible for multiple deformation in the Greenvale Province and reactivation of domain-bounding faults. [ABSTRACT FROM AUTHOR]

Abstract: Integrated Sensitive High Mass Resolution Ion Microprobe (SHRIMP) U–Pb zircon, geochemical and Sm–Nd isotopic data from the late Archaean Gawler Craton, southern Australia, constrain major basin-forming and magmatic processes to the interval 2560–2500Ma. This terrane represents a convergent margin associated with the second half of a full global Wilson cycle, during which continental fragments formed between 2780 and 2590Ma amalgamated with younger cratons, perhaps forming the Earth''s first supercontinent. Metasedimentary rocks in the central and southern Gawler Craton deposited between 2535 and 2500Ma, have dominant detrital SHRIMP U–Pb zircon ages, geochemical and ɛ Nd signatures which reflect input from predominantly felsic, juvenile to moderately evolved late Archaean crust. Geochemical patterns in ca. 2560–2500Ma felsic to intermediate igneous lithologies that in part were produced during on-going basin development, suggest affinities with an arc-like environment, and have a range of ɛ Nd values that indicate variable crustal contamination of primitive arc components. However, approximately coeval komatiites have geochemical and ɛ Nd signatures consistent with a mantle–plume origin. We envisage a tectonothermal regime for development of the late Archaean Gawler Craton that reflects interaction between a convergent margin and mantle–plume, in which sedimentary deposition occurred during active basin development in a back-arc or arc-rift setting. Basin formation and associated magmatism was terminated by regional granulite grade metamorphism and crustal thickening during the ca. 2500–2400Ma Sleafordian Orogeny, which was proceed by ∼400Ma of tectonic quiescence. This suggests that the Sleafordian Orogeny was driven by collision between continental components, leading to the formation of a continental interior. While the late Archaean Gawler Craton is younger than prodigious late Archaean metallogenic provinces associated with the first half of a full global Wilson cycle (ca. 2780–2590Ma), there are important lithological and tectonic similarities to those mineralized systems. [Copyright &y& Elsevier]

Presents a study on detrital-zircon age spectra for sedimentary rocks of the Delamerian orogen in southern Australia. Methodology used to conduct study; Results of study; Discussion on findings.