Details of Award
NERC Reference : NER/A/S/2003/00537
Transformation microstructure and seismic anelasticity in mantle minerals.
Grant Award
- Principal Investigator:
- Professor S Redfern, University of Cambridge, Earth Sciences
- Grant held at:
- University of Cambridge, Earth Sciences
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Environmental Risks and Hazards
- Science Topics:
- Properties Of Earth Materials
- Mantle & Core Processes
- Abstract:
- The origin of anelasticity in the lower mantle is uncertain, yet it most certainly is observable as attenuation in seismic waves (measured in terms of the quality factor as Q-1). One possible cause is the thermally-activated motion of intragrain domain walls that result from ferroelastic phase transitions. Here, we determine the effect of domain walls and martensitic microstructure on the seismic-frequency temperature-dependent mechanical properties of perovskites and pyroxenes. We shall measure the elastic and anelastic properties of crystalline phases that are close structural analogues of the perovskite phases believed to make up more than 70% of the lower mantle. We shall probe super-elastic behaviour associated with the motion of domain walls. The programme will ascertain the extent to which ferroelastic transformation twinning is a credible source of anelasticity and rheological weakening in the lower mantle. Furthermore, we shall determine the stress dependence of martensitic behaviour in orthorhombic pyroxenes, relevant to the upper mantle. In this way we aim to test the hypothesis that transformation-induced microstructure may play an important role in controlling seismic attenuation and rheology from the crust to the core mantle boundary. Experimental results will be complemented by parallel computational studies of domain wall behaviour and the role of point defects on their mobility. The results will provide an underpinning understanding of the influence of microstructural controls in minerals on bulk seismic features of the inner Earth.
- NERC Reference:
- NER/A/S/2003/00537
- Grant Stage:
- Completed
- Scheme:
- Standard Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £199,705
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Staff | Total - Other Costs | Total - Equipment | Total - Indirect Costs |
|---|---|---|---|---|
| £6,266 | £109,769 | £21,367 | £11,810 | £50,494 |
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