Petrogenesis of Havre Volcano in the Kermadec Arc: 2012 Eruption of a Chemically Homogeneous Rhyolite

The 2012 Havre submarine eruption produced a 1.5 km 3 bulk rock volume or 0.52 dense equivalent of rhyolite emplaced as minor lava flows, field sunken seafloor pumice, and volumetrically dominant pumice raft. This moderately large medium-K (1.4–1.6 wt% K 2 O) is relatively chemically homogeneous (71.5–73.0 SiO ), no trace element variation cryptic zoning has been detected despite the textural diversity material. Radiogenic isotope ratios ( 87 Sr/ 86 Sr 0.703693–0.703744; 206 Pb/ 204 Pb 18.7648–18.7781; 208 38.587–38.605; 143 Nd/ 144 Nd 0.513001–0.513020) demonstrate sourced from mantle similar to regional eruptive products Kermadec arc volcanic front. Providing some further insight into magmatic system an abundance diverse fragments primarily embedded in banded raft pumice. Embedded represent variety fresh hydrothermally altered lavas ranging composition basaltic rhyolitic (50.6–72.3 ) are likely varying depths within conduit during explosive fragmentation. fragments, therefore, earlier erupted that constructed volcano snapshots petrogenetic history Havre. Magnesian augite andesite compositional range (En 55 Fs 12 Wo 33 En 39 26 35 previously documented antecrystic clinopyroxene observed Herein, we explain how this crystal-poor can be generated oceanic setting based on major models. Rhyolite-MELTS crystal fractionation models indicate mineral compositions plagioclase (An 55–78 magnesian augites 53 10 37 40 34 primary phases would crystallize andesitic melt compositions. Modeling indicates forerunner magma must dry (∼1 H 0) low-K tholeiitic basalt require ∼78% crystallization at different pressures ultimately generate rhyolite.