Details of Award
NERC Reference : NE/C506921/1
Phase relations and physical properties of aluminous Mg-silicate perovskites and implications for Earth's lower mantle.
Grant Award
- Principal Investigator:
- Professor M Walter, University of Bristol, Earth Sciences
- Grant held at:
- University of Bristol, Earth Sciences
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Global Change
- Environmental Risks and Hazards
- Science Topics:
- Planetary science
- Properties Of Earth Materials
- Mantle & Core Processes
- Abstract:
- Mg-silicate perovskite (MgPv) is the most abundant mineral in the lower mantle. Geophysical and geochemical models depend critically on accurate data for the thermoelastic and crystal chemical properties of this phase. Recently, it has been revealed that solution of minor amounts of Al into MgPv can produce a dramatic softening of the orthorhombic structure, with compressibility increasing by about 10% relative with addition of only 5 mol% Al. Thermoelastic properties depend on how Al substitutes into the perovskite structure, of which there are two primary mechanisms. One a charge-coupled substitution (2Al3+Mg2++Si4+), and a second involving vacancy formation (2A13+2Si4++VO2-) leading to a defect-structured MgPv. To accurately constrain lower mantle composition and dynamic models it is critical to determine which substitution mechanism, or to what extent both substitution mechanisms, operate in the lower mantle. Further, if the vacancy forming mechanism is important, the perovskite structure may accommodate a considerable amount of water and other incompatible elements. I propose to make a systematic study of the pressure, temperature and compositional dependence of phase relations in the MgO-rich region of the system MgO-AlOl .5-SiO2, using both multi-anvil and diamond anvil cell (DAC) high P-T techniques, coupled with a multi-faceted analytical approach including electronmicroprobe analysis, high-resolution TEM analysis, and synchrotron-based micro X-ray diffraction. The data obtained will be used to determine if a zone exists in the uppermost portion of the lower mantle where defect perovskites are stable. Such a zone would have important geophysical and geochemical consequences.
- NERC Reference:
- NE/C506921/1
- Grant Stage:
- Completed
- Scheme:
- New Investigators Pre FEC
- Grant Status:
- Closed
- Programme:
- New Investigators
This grant award has a total value of £38,311
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Other Costs | Total - Equipment |
|---|---|---|
| £6,116 | £16,920 | £15,275 |
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