Northern Tonga Arc and Fonualei Rifts: initial results from the NoToVE (SS11/2004) Research Voyage

Abstract

The SS11/2004 research voyage of the Marine National Facility to the northern Tonga Arc and adjacent Fonualei Rifts (backarc) discovered several new submarine, basalt-to-rhyolite volcanic centres (stratovolcanoes and massive caldera systems) in the Arc. Numerous sector and caldera collapses were likely tsunamigenic. Fonualei Rifts lavas are a global backarc end-member with markedly low Na contents reflecting a highly refractory mantle wedge source coupled with high degrees of partial melting. The southern Rifts have captured the entire supra-subduction zone magma flux over about 150 km of strike; adjacent Arc volcanoes are inactive and carbonate capped.