The distribution and circulation of fluids in the Earth’s interior are connected to volcanic activity, earthquakes, and plate tectonics in general. In this project, the chemical elements (termed “volatiles”) hydrogen (H) and carbon (C) at depths of several hundreds of kilometers below the Earth’s surface (i.e., in the upper mantle) are of particular interest. These light elements provide key information to understand the temperature and chemical composition of the Earth’s mantle, as well as the processes that have shaped the interior of our planet. This team will focus on H,C-bearing mantle rocks using a combination of techniques that are carefully selected to reveal the rock chemistry and the electrical response at high pressures and temperatures. This project is at the frontier of high-pressure research because of the high degree of synergy between two primary techniques (Raman spectroscopy and impedance spectroscopy), and the plan to make these measurements simultaneously at high pressures and temperatures. Electrical measurements (in situ) and vibrational spectroscopy (in & ex situ) are a powerful combination that is anticipated to significantly advance our understanding of transport, dehydration, and decarbonation in volatile-bearing minerals. This work will help develop an advanced model of the transport of volatiles in subduction zones, and presents an opportunity to foster multi-disciplinary collaborations between mineral physics, chemistry, and geophysics. These PIs