Exotic island arc Paleozoic terranes on the eastern margin of Gondwana: Geochemical whole rock and zircon U–Pb–Hf isotope evidence from Barry Station, New South Wales, Australia

摘要: Abstract Early Paleozoic intra-oceanic terranes crop out along the Peel-Manning Fault System, in southern New England Orogen, NSW Australia. These are Cambrian ophiolitic Weraerai terrane and Siluro-Devonian island arc Gamilaroi terrane. There has been debate whether these formed at Gondwana margin or if they intra-oceanic, were accreted to later Paleozoic. Major-trace-REE elemental data indicate a supra-subduction environment. Rare zircons extracted from gabbro-plagiogranite suites Barry Station yield U–Pb zircon date of 504.9 ± 3.5 Ma with initial eHf values + 11.1 indicating juvenile source. Amphibole-bearing felsic dykes net-vein complexes also found within gabbro 503.2 ± 5.7 Ma + 11.6. coeval age their host rocks we propose represent partial melts mafic crust during circulation seawater. The trondhjemites prehnite-pumpellyite–greenschist metamorphic grade yielded very few an 413 ± 8.7 Ma. Zircon range + 5.0 + 2.9, input evolved crustal source, unlike purely oceanic enriched LREE have low K2O K2O/Na2O ratios strong negative Nb anomalies consistent zone environments. Multiple subduction zones may well existed Panthalassa Ocean early-mid Weraerai-Gamilaroi being onto Gondwanan latest Devonian.