Mantle heterogeneity beneath the Cenozoic volcanic provinces of central Victoria inferred from trace-element and Sr, Nd, Pb and Hf isotope data

Abstract

Volcanic rocks in central Victoria play a key role in unravelling magmatic relationships within an extensive zone of Late Mesozoic to Quaternary volcanism in southeastern Australia. In this study, new bulk-rock major, trace-element and Sr, Nd, Hf and Pb isotope data are presented for 20 samples of Late Cenozoic mafic volcanics from the central Victorian region. Mineral chemistry and bulk-rock analyses confirm that all samples can be treated as liquid compositions and that some were probably primary magmas. On the basis of incompatible trace-element and isotope ratios, processes such as magma mixing and crustal assimilation can be largely ruled out, and significant mantle-source heterogeneity..