Scott Akhtar-Lewis

Effects of Stress on the Olivine–Spinel Phase Transformation in the Mantle: Griggs-Type Deformation Experiments Using Mg2GeO4 as an Analogue

Name: Scott Akhtar-Lewis
Primary Supervisor: Prof. John Wheeler
Year: 3
Discipline: Geology
Presentation type: Oral presentation with slides
Project Title: Effects of Stress on the Olivine–Spinel Phase Transformation in the Mantle: Griggs-Type Deformation Experiments Using Mg2GeO4 as an Analogue

Abstract:

The transformation of olivine (Mg2SiO4) to the spinel phase is an important reaction that separates the upper and lower mantle. The effects of pressure and temperature on this phase transformation is well understood. However, the extent to which stress affects this phase transformation is not clear. This session will discuss deformation experiments using Mg2GeO4 (olivine) that has been used as an approximate analogue for olivine as it transforms into spinel at lower pressures and temperatures than its silicate counterpart. The use of a germanium-based analogue enables larger samples than possible for the silicate system and allows for extensive microstructural investigations. Understanding how stress influences the speed of the olivine to spinel phase transformation and the mechanism in which it does so at small grain scale, will have broader implications for understanding mantle dynamics.