David Hilton:

Associate Professor of Geochemistry

Scripps Institution of Oceanography, UCSD

I am a geochemist focusing on the isotopes of the noble gases and their application to a wide range of topics in the earth and environmental sciences. These topics include igneous petrology, mantle geodynamics, arc-related tectonics and volcanism, earthquake monitoring, hydrogeology and the formation of natural gases. A significant proportion of my research involves sampling volcanoes - different types (shield volcanoes), strato-volcanoes, even submarine volcanoes) located in different tectonic settings.

For example, I have worked on mantle plumes at oceanic islands such as Iceland, Hawaii and La Palma (The Canaries). At these locations, I have been caught in a snowstorm in mid-summer (on the top of Hekla, Iceland) and experienced the frigid conditions of a 3-man submarine - while collecting hydrothermal fluids from Loihi seamount (off the Big Island of Hawaii). I have also sampled volcanoes situated along plate margins (subduction zones) - in the tropical rainforests of Indonesia, the island paradises of the eastern Caribbean (including the currently active island of Montserrat) and the dizzying altitudes of the high Andes (Chile and Argentina).

At each volcano, irrespective of setting, I try to collect a variety of samples (geothermal fluids, fumaroles, hydrothermal vents, boiling mud pots, young lavas, groundwaters) as they all contain volatiles (including the noble gases) derived from the melting of magma. These samples are then transferred back to the laboratory for chemical and isotopic analyses. The Mariana expedition, in this respect, will be no different - and I'll be targeting both fluid samples (such as fumaroles) and young lavas flows for their intrinsic volatile contents.

With analysis in hand, the aim will be to quantify the flux of magmatic volatiles emitted via volcanism in the Marianas as a first step in considering the magnitude and nature of volatile fluxes along the entire strike of the IBM (Izu-Bonin-Mariana) system - all the way to Japan. In this way, we hope to understand how the subducting slab (including its sedimentary veneer), overlying mantle wedge and arc crust interact and control magma formation at one of the most active volcanic margins worldwide.