Melting conditions beneath the Newer Volcanics Province from probabilistic inversions

The Newer Volcanics Province (NVP) represents mainland Australia’s youngest intraplate volcanism. Despite past studies, the exact mechanism of magma generation is heavily debated, with the exact source composition and melting environments remaining unclear. Previous models of NVP magma genesis have tended to focus on either geochemical or geophysical arguments. In this work, we use an integrated approach using both geochemical and geophysical observations to explain mantle processes. Geochemical data from the NVP is screened to obtain a dataset containing <2 Ma samples that represent primitive melts from peridotitic sources. A newprobabilistic inversion method is applied to the samples in conjunction with a recently developed mantle melting model to evaluate the melting conditions in the mantle. A separate geophysical model of the present-day thermochemical structure of the lithosphere and sublithospheric upper mantle is created by jointly inverting available seismic datasets. The results from the geochemical and the geophysical models suggest the presence of a thin, hot lithosphere. Furthermore, findings indicate the source is relatively depleted in all major elements except FeO but enriched in rare earth elements. The source is also suggested to have developed this signature due to a substantial input from the sub-continental lithosphere mantle.