Olivine is the dominant mineral in the earth mantle. The olivine to its high pressure polymorphs phase transformation has wide implications for many mantle dynamic processes. The 410km discontinuity is usually considered to be caused by the olivine- wadsleyite transformation. And olivine's preferred orientation is important for understanding the rheology and seismic anisotropy in the upper mantle. The α-β transformation of olivine possibly influences the dynamics of the subducting slab, and it may also lead to rheologieal weakening which strongly affects the mechanical properties of subducting slabs. The recent developments of phase transformation are reviewed in this paper including the following area; the in-situ X-ray diffraction and the quench methods; the apparatus used; the influence of press-scale to the precision of the test results; the nucleation and growth mechanism and the shearinduced mechanism. Then the experiment results of (Mgo 9Fe 0 1 )2SiO4 olivine-wadsleyite phase transformation were reported. Ten runs with different P-T conditions were performed. β phase was obtained in some runs and a coexistence of α and β phases were observed in other runs. Therefore, the first-hand in-situ X ray diffraction transformation experimental results of ( Mg, Fe) 2SiO4 olivine were obtained. And the transformation mechanisms were discussed based on FTIR, optical and electrical microscopy observations.
|Original language||English (US)|
|Number of pages||6|
|Journal||Acta Petrologica Sinica|
|State||Published - May 2009|
- In-situ x ray diffraction
- Phase transformation