Lithospheric mantle evolution beneath northeast Australia

Temporal correlation of magmatic-tectonic events in the lower and upper crust in north-east Australia

“…The coincidence of the Atherton lherzolite xenolith Sm-Nd isochron age of 275 Ma with the widespread 265 to 280 Ma granitoid magmatism (Bultitude and Champion 1992;Davis et al 2002) led Handler et al (2005) to suggest the growth of the lithosphere beneath the Atherton Province. Handler et al (2005) also proposed that the early Palaeozoic lithospheric mantle below the lower crust may have been removed and replaced with a new mantle during the Permian magmatism, whereas Murgulov et al (2011) suggested that the scattered fragments of the *1.75 and 1.23 Ga metasomatised cratonic lithosphere have been embedded within the lithospheric mantle column beneath the Atherton Province since at least *0.44 Ga. No age data have been obtained on the Atherton granulite xenoliths in this study. However, based on the isotopic data on spinel-lherzolite xenoliths and granitoids, it can be suggested that extensional tectonic processes in the back-arc setting initiated movement of asthenosphere-derived melts/fluids through the lithospheric mantle, causing intrusion of mantle-derived basaltic magmas in the lower crust, followed by compressional tectonism and granitoid magmatism in the overlying crust on and off the craton.…”

Middle–Late Paleozoic Australia–Asia convergence and tectonic extrusion of Australia

“…These show Nd model ages indicating possible derivation from Lower Proterozoic crust, equilibration at mid-to lower crustal depths at temperatures too high for normal geothermal gradients (Kay and Kay, 1983) and U-Pb zircon crystallization ages between 300 and 400 Ma, and point altogether to an intense Late Paleozoic lower crustal heating event (Rudnick, 1988). This age range is supported by Rhenium-depletion model ages of 350 Ma and 440 Ma for metasomatic events in lithospheric mantle-derived xenoliths from the Atherton Province and the Chudleigh Province respectively (Murgulov et al, 2011), studied previously by Rudnick. The xenolith data apparently record an advective heat event in lower crust of the wider TOS during the ASO (450/400-330 Ma).…”