A unifying hypothesis to explain widespread
volcanism across Eastern Australia and Zealandia
← Muller et al. (2016), EPSL
Mortimer et al. (2017), GSA today
What drives non-age progressive eruptions
in Eastern Australia and Zealandia?
Convective eddy that forms at the trailing edge of sharp discontinuities in lithospheric thickness
Davies et al. 2014, Farrington et al 2010, Demidjuk et al. 2007
Shear-driven upwellings in the mantle that induce partial melting at the base of the lithosphere
Conrad et al. 2011
Park et al. 2019, Nature Geoscience
Our proposed model
King et al. 2015, Geology
The most pronounced pulse of volcanism are correlated with bursts in slab flux.
21 Ma: Rapid eastward migration of the Tonga-Kermadec trench. Ontong Java Plateau choked the Melanesian Trench and forced subduction to migrate inbound to the Trobriand Trough.
4 Ma: Reversal in subduction polarity along the northern margin of the Australian plate may have detached the formerly subducting Pacific plate slab along the Melanesian Trench.
Slab flux: the volumetric rate of material being consumed at subduction zones
Slow S-wave velocity in the transition zone (averaged 410-660km) suggests thermo-chemical anomalies - possibly associated with melt.
P-wave anomaly images indicate flat subduction in the north of the Tonga-Kermadec Trench, and transitions to steeper subduction angles in the south.
We compared the variation in isotope ratios across lava field volcanoes and age-progressive central volcanoes and leucitite suites (hotspot chains).
Intraplate volcanism is triggered by the release of subducted volatiles
in the transition zone during pulses in slab flux.
Multiple plumes are not required to explain the majority of volcanism in eastern Australia - Zealandia.