Career: the influence of cation substitution on the hydrous phases of the lower mantle

Active Project Grant Awarded Last action

Award ID
2338444
Recipient
Awarding agency
Obligated
$619,867

Award facts

Assistance listing
47.050 Geosciences
Completion date 48% complete
Place of performance
Sewanee, TN 37383, USA

Award details come from USAspending.gov.

Description

As the agency reported it.

Abstract
Plate tectonics connects the hydrosphere to a water cycle deep in the earth, as hydrogen-bearing materials are cycled into the planet's interior. The recent discovery of multiple natural diamond inclusions from the deep earth that contain hydrous phases is compelling evidence that the water cycle of the deep earth may extend even deeper than was originally believed. This study will use a combination of computational models and experiments to evaluate the stability and geophysical properties of hydrous phases believed to be stable at the conditions of the earth's lower mantle. Although these are expected to be minor phases, the potential for hydrogen storage in the lower mantle is still considerable, as IT comprises approximately 56% of the earth's volume. This project will fund critical training for an early career scientist who will be guided through learning how to balance teaching, research, and student mentorship at a primarily undergraduate institution. A complementary educational component of this project is to develop a virtual reality application that will help undergraduate geology students develop spatial reasoning skills, with a particular focus on fostering equity and inclusion for neurodiverse students with visual-spatial deficits. Phase D [MGSI2O4(OH)2] and phase H [MGSIO2(OH)2] are dense hydrous magnesium silicates (DHMSS) that are expected to play a key role in the hydrogen cycle of the lower mantle. Importantly, FE- and AL-substitution has a profound influence on the stability and properties of these phases. In fact, phase H forms a solid solution with D-alooh and E-feooh, forming a potentially continuous hydrous reservoir with stability down to the core-mantle boundary. This project combines AB initio calculations with high-pressure, high-temperature vibrational spectroscopy and single-crystal X-RAY diffraction to evaluate the geophysical properties of intermediate compositions of AL, FE-bearing phase D and phase H, and to probe how cation substitution affects pressure-induced hydrogen bond symmetrization, which can have a substantial influence on the bulk modulus and its pressure derivative. First principle calculations will systematically evaluate how cation substitution influences the pressure-dependent properties and hydrogen accommodation in these phases, providing a theoretical framework for high-pressure experiments. Combining crystallographic and spectroscopic approaches will provide detailed information on the interatomic forces and bonding environments of hydrogen within these phases, helping explain why these phases are stable at extreme pressures and temperatures. 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.- subawards are not planned for this award.

Transactions

Action Obligated Date
Amendment $413,843
Amendment $91,693
Original award $114,331

Quick answers

Who received award 2338444?

2338444 was awarded to The University Of The South by Division of Earth Sciences (National Science Foundation) on June 1, 2024.

How much is award 2338444 worth?

$619,867 has been obligated on 2338444.

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