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Understanding dynamics across phase transformations and the spatial distribution of minerals in the lower mantle is crucial for a comprehensive model of the evolution of the Earth’s interior. Using the multigrain crystallography technique (MGC) with synchrotron x-rays at pressures of 30 GPa in a laser-heated diamond anvil cell to study the formation of bridgmanite [(Mg,Fe)SiO 3 ] and ferropericlase [(Mg,Fe)O], we report an interconnected network of a smaller grained ferropericlase, a configuration that has been implicated in slab stagnation and plume deflection in the upper part of the lower mantle. Furthermore, we isolated individual crystal orientations with grain-scale resolution, provide estimates on stress evolutions on the grain scale, and report {110} twinning in an iron-depleted bridgmanite, a mechanism that appears to aid stress relaxation during grain growth and likely contributes to the lack of any appreciable seismic anisotropy in the upper portion of the lower mantle.
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Exploring microstructures in lower mantle mineral assemblages with synchrotron x-rays
Understanding spatial distribution of phases as well as dynamics across phase transformations in the lower mantle are crucial understanding the evolution of the Earth’s interior. Studies at high pressures and temperatures have previously relied on powder diffraction or single crystal methods which have limitations in spatial resolution during dynamic processes. Here we apply the novel multigrain crystallography technique at high pressure and temperature in a laser heated diamond anvil cell (LH-DAC) to study the formation of the Earth’s most abundant mineral bridgmanite MgSiO3 from a natural olivine sample. We constrain the twinning relationship in the bridgmanite phase at high pressure with grain-size resolution as well as evidence for an interconnected network formed by the weaker ferropericlase phase which could contribute to slab stagnation and plume deflection
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- PAR ID:
- 10329118
- Date Published:
- Journal Name:
- Science advances
- Volume:
- 7
- ISSN:
- 2375-2548
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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