NAI
2009 Annual Science Report
University of Hawaii, Manoa
Reporting | JUL 2008 – AUG 2009
Hydrogen in Nominally Anhydrous Minerals
Project Summary
The amount of water in the Earth’s interior is not known. Experiments have shown that at high pressure, the high-pressure forms of the minerals that make up the Earth’s mantle can contain significant hydrogen substituting for magnesium. We are carrying out a series of experiments to determine how much hydrogen (=water) can be contained in these high-pressure minerals. Mineral samples produced at mantle pressures in the presence of water are being measured using the Cameca ims 1280 ion microprobe at the Unversity of Hawaii to determine the maximum amount of water that each mineral can hold at high pressure, providing a constraint on the possible water content of the mantle.
Project Progress
We have carried out the first round of hydrogen abundance measurements on wadsleyite and ringwoodite (high-pressure form of olivine), and majorite garnet using the Cameca ims 1280 ion microprobe at the University of Hawaii. The initial sample preparations were not adequate, so we had to remount and repolish the samples. But after this minor setback, the measurements were quite reproducible and the inferred abundances agreed well with FTIR determinations in two samples that had been well characterized previously. Dr. Smythe is now preparing a new suite of samples produced under a range of conditions and a second round of measurements is tentatively schedules for February, 2010.
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PROJECT INVESTIGATORS:
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PROJECT MEMBERS:
Gary Huss
Project Investigator
Joseph Smyth
Co-Investigator
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RELATED OBJECTIVES:
Objective 1.1
Formation and evolution of habitable planets.