Experimental determination of the electrical conductivity of hydrous bridgmanite for constraining lower mantle water content

University Of Hawaii, Honolulu

Investigators

Abstract

Water significantly influences Earth's evolution and habitability, yet the total amount and distribution of water deep inside our planet remain uncertain. Determining the water content in deep regions of the planet is essential, as it impacts processes governing Earth's internal convection, thermal evolution, and long-term stability. Earth's lower mantle, comprising more than half of Earth's volume, largely consists of the mineral bridgmanite. This mineral can store dissolved water, which affects the electrical conductivity of the material. This project will measure the electrical conductivity of bridgmanite with dissolved water under lower mantle conditions to determine the impact of water on conductivity. Such constraints will critically enhance our understanding of Earth's initial formation, internal distribution of water, and deep-water cycling over geological time. Additionally, the research outcomes will broadly benefit computational modeling studies on Earth's interior, advance interdisciplinary knowledge, and provide valuable research and mentoring opportunities for early career scientists and students in Earth and planetary sciences. This project aims to experimentally determine the effects of water content on the electrical conductivity of (Fe,Al)-bearing bridgmanite over a range of 0–1000 ppm H₂O under pressures and temperatures corresponding to Earth's lower mantle. Using an innovative method specifically developed for resistance measurements under extreme high-pressure, high-temperature conditions, the team will systematically measure bridgmanite's electrical response as a function of water content. These laboratory measurements will then be compared with geophysical electrical conductivity profiles obtained through geomagnetic observations, enabling accurate constraints on lower mantle hydration. By addressing a notable gap in high-pressure mineral physics, this research will significantly advance scientific understanding of Earth's deep interior, including constraints on its initial water content, physicochemical evolution, mantle rheology, and internal dynamics. This project is jointly supported by the Structure and Physics of the Solid Earth and Chemical Evolution of the Solid Earth and Volcanology programs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.