Peralkaline granites near Temora, southern New South Wales: Tectonic and petrological implications

Abstract

The Devonian Narraburra Granite in southern New South Wales is located on the western margin of the Bogan Gate Synclinorium in the Temora Rift and is associated with other post- or late orogenic sodic granites and tholeiitic and transitional basic intrusive rocks. This region represents the rifted boundary between the Wagga-Omeo and Kosciusko Terranes. The granite is peralkaline (Al2O3/Na2O + K2O = 0.95–0.96), contains aegirine and arfvedsonite, and is only the third occurrence of peralkaline granite recorded in the Lachlan Fold Belt of southeastern Australia. Chemically the Narraburra Granite is distinct with high SiO2, total alkalis, Zr, Nb, Ga, Y and rare earth element abundances, relatively low Al2O3, MgO and CaO, and a pronounced negative Eu anomaly. The geochemical features are similar to those exhibited by A-type granites of the Bega Batholith, but the negative Eu anomalies are more pronounced (Eu/Eu* = 0.08–0.16) and the overall shape of the rare earth patterns is different. The abundances of Ba, ...