Intraplate Volcanism Triggered by Bursts in Slab Flux

Home , Intraplate volcanism

EGU21-6857 https://doi.org/10.5194/egusphere-egu21-6857 EGU General Assembly 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.

Intraplate volcanism triggered by bursts in slab flux

Ben Mather1, Dietmar Muller1, Maria Seton1, Saskia Ruttor2, Oliver Nebel2, and Nick Mortimer3 1The University of Sydney, School of Geoscience, Sydney, Australia ([email protected]) 2School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC 3800, Australia 3GNS Science, Dunedin, New Zealand

Long-lived, widespread intraplate volcanism without age progression is one of the most controversial features of plate tectonics. The eastern margin of Australia and Zealandia has experienced extensive mafic volcanism over the last 100 million years. A plume origin has been proposed forthree distinct chains of volcanoes, however, the majority of eruptions exhibit no clear age progression. Previously proposed edge-driven convection, asthenospheric shear, and lithospheric detachment fail to explain the non age-progressive eruptions across the~5000 km wide intraplate volcanic province from Eastern Australia to Zealandia. We model the subducted slab volume over 100 million years and find that slab flux drives volcanic eruption frequency, indicating stimulation of an enriched mantle transition zone reservoir. Volcanic isotope geochemistry allows us to distinguish a HIMU reservoir (>1 Ga old) in the slab-poor south, from a northern EM1/EM2 reservoir, reflecting a more recent voluminous influx of oceanic lithosphere into the mantle transition zone. We provide a unified theory linking plate boundary and slab volume reconstructions to upper mantle reservoirs and intraplate volcano geochemistry.