Scales of compositional heterogeneity in volcanic products of the 2012 eruption of Havre volcano, Kermadec arc

Abstract:

Our understanding of the nature of magma systems that feed silicic submarine eruptions has traditionally been hindered by a reliance on dredged sample sets, which can lack detailed chronostratigraphic information and may not represent a complete suite of an eruption’s products. The mapping, exploration and sampling at Havre volcano expedition (MESH) has provided an opportunity to overcome these challenges and investigate the compositional characteristics of a magma system that fed the largest documented explosive submarine eruption in exceptional detail. Paired AUV–ROV mapping, sampling and observation of the seafloor was used by the MESH team to unravel a complex eruption history that comprised the effusion of lavas and domes from 13 different vents, dispersal of pumice deposits and mass wasting at the caldera volcano. The reconstruction of the eruption history using stratigraphic relationships constrained by AUV-ROV operation presents a superior temporal and spatial framework for petrological and geochemical studies compared to that offered by dredge sampling. We present preliminary petrographic information and whole-rock major and trace element data for the volcanic products of the 2012 Havre eruption that are placed within a high-resolution spatial and stratigraphic framework. The geochemical characteristics of seafloor and floated pumice deposits and effusive products are compared to assess the heterogeneity of the magma system and whether composition played a key role in eruptive style. This work will underpin further geochemical studies to be undertaken on the sample suite in order to investigate the magma storage conditions and potential eruption triggering mechanisms.