| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | July 7, 2014 |
| Latest Amendment Date: | July 7, 2014 |
| Award Number: | 1416979 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Robin Reichlin
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 1, 2014 |
| End Date: | May 31, 2018 (Estimated) |
| Total Intended Award Amount: | $340,000.00 |
| Total Awarded Amount to Date: | $340,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
572 UCB Boulder CO US 80309-0572 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Petrology and Geochemistry, Geophysics |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Liquid water is essential to life, and the search for habitable planets within our solar system and elsewhere in the galaxy has come down to a search for planets on which liquid water can exist. Earth is a water planet, but how the Earth acquired its water is a subject of intense debate, measurement, experiment, and theoretical calculation. There are not yet solid constraints on how much water the Earth has, because the components of water, atoms of hydrogen and oxygen, are incorporated into the solid silicate minerals of the interior, and this water can be exchanged with the surface reservoir over the long stretch of geologic time. This is an experimental research project to measure the solubility of hydrogen in the solid, oxygen-based silicate minerals of the deep interior of the Earth in order to place some constraint on how much hydrogen the planet can harbor in this region which constitutes more than half the mass of the planet. The mineral crystals, which are quenchable, will be grown at high pressure and temperature, and their physical properties (density and seismic velocity) will be measured. The principal objective is to constrain the amount of water (hydrogen plus oxygen) that can be stored in the interiors of Earth-like planets, and how this may affect the dynamics of the deep interior.
This is a project to synthesize and characterize hydrous magnesium silicate and oxide phases thought to be stable in Earth's interior at depths of 600 to 2900 km. In collaboration with other research groups, principally in Germany, the investigators have synthesized samples of MgSiO3 in several different crystal structures under hydrous conditions with various minor substituents, principally aluminum and iron. They have found significant solubility of H in akimotoite (ilmenite-structure), majorite (garnet structure), and in aluminum-bearing perovskite. This project renewal is to focus on H solubility in aluminous perovskite. MgSiO3-perovskite is thought to be the most abundant mineral in the interior and potentially the largest reservoir of H in the planet. Synthesized high pressure minerals will be analyzed for crystal structure, chemical composition and hydrogen content. Measurements of elasticity will be made in order to constrain the effect of hydration on seismic velocity. The data obtained should permit a greater understanding of the crucial role of hydrogen in mantle dynamics and further constrain the amounts of hydrogen that may be stored in the interiors of Earth-like planets.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This is a project to experimentally synthesize and characterize minerals that might occur at depths in the Earth of 500 to 1000 km (300 to 600 miles) under hydrous conditions in order to understand how the element hydrogen may be incorporated and retained in planetary interiors. The Earth in this region is solid rock composed of solid minerals composed of oxygen, silicon, magnesium, iron, aluminum and other minor elements. Because oxygen in these minerals is abundant, incorporation of hydrogen in trace, minor or major amounts may control the abundance of water on the surface.
Intellectual merit: PI Smyth and students collaborated on high pressure mineral syntheses at the University of Bayreuth in Germany which were later characterized by electron microprobe and ion microprobe chemical analysis, X-ray diffraction, and Raman and infrared spectroscopy. Results showed that abundant hydrogen can be stored in abundance in the transition zone at depth s of 400 to 660 km depth. Below 660 km depth the solubility in the major minerals is much lower than at shallower depths. At depths below 660 km the most abundant mineral is thought to be bridgmanite, a magnesium-iron silicate. We synthesized bridgmanite with minor aluminum with up to 0.2% H2O by weight. In addition to trace hydrogen incorporation in nominally anhydrous minerals, the project synthesized and characterized several hydrous silicate phases that might occur in the interior.
It is likely then that the lower mantle of the Earth contains more water than the surface oceans although this water is not liquid but incorporated in solid silicate minerals. Hydrogen may thus be an abundant minor element incorporated throughout the planetary interior incorporated early in the accretion of the planet. This study increases the likelihood that water planets similar to Earth may be found among the thousands of extra-solar planets recently identified in our galaxy.
Broader impacts: Collaborators include researchers at Bayreuth (Germany), Padua (Italy), Oxford (UK), Zürich (Switzerland), and Wuhan (China) as well as Stanford, Princeton, Northwestern, UCLA, Ohio State, and UT Austin in the US. Graduate student Li Zhang was supported under this project. He completed his Ph.D in 2017 and is currently employed as a post-doctoral fellow at Peking University in Beijing, China. Undergraduate students, Jason VanFosson and Rhiana Henry were employed under this grant during Spring and summer semester 2015, 2016, 2017 and 2018.
Last Modified: 10/25/2018
Modified by: Joseph R Smyth
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