Science and Engineering

Arizona State University

Peter R. Buseck, Jun Wu, S.-H. Dan Shim, Kurt Leinenweber, Zachary Sharp, Stephen Romaniello, Ariel Anbar, Steve Desch, Linda Elkins-Tanton
Tempe, AZ
December 2015

The origin of Earth’s water and hydrogen is a long-debated, yet unsolved mystery.  Current models dismiss the theory that a significant source is solar-nebula H2 and H2O ingassed into an early magma ocean.  This theory would require that substantial amounts of isotopically light hydrogen be removed from the mantle and presumably stored in the core.  Data supportive of the ingassing hypothesis are lacking because experimental measurements are extremely challenging.  This group of researchers developed breakthrough techniques enabling previously impossible measurements of hydrogen solubility and isotopic fractionation in molten iron at the high pressures and temperatures characteristic of the early Earth’s magma ocean.  The method encapsulates iron and hydrogen in carbon nano-onions using innovations in electron microscopy and diamond-anvil-cell pressurization, producing stable iron hydride for subsequent analysis by mass spectrometry specially designed for nanogram quantities of hydrogen.  They will use experimental data to model ingassing of proto-atmospheres into magma oceans and to predict the isotopic composition and amount of water on Earth.  Successful demonstration of the method would significantly advance high-pressure technology.  Data supporting the ingassing hypothesis would be a game changer, with impact reverberating across geophysics, geochemistry, and planetary science.

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