The postspinel boundary in pyrolitic compositions determined in the laser-heated diamond anvil cell


Title

The postspinel boundary in pyrolitic compositions determined in the laser-heated diamond anvil cell

Publication Type
Journal Article
Year of Publication
2014
Journal
Geophysical Research Letters
Volume
41
Issue
11
Pagination
3833 – 3841
Date Published
Apr-06-2015
Publication Language
eng
Citation Key
2691
Abstract
In situ multianvil press (MAP) studies have reported that the depth and the Clapeyron slope of the postspinel boundary are significantly less than those of the 660 km discontinuity inferred from seismic studies. These results have raised questions about whether the postspinel transition is associated with the discontinuity. We determined the postspinel transition in pyrolitic compositions in the laser-heated diamond anvil cell (LHDAC) combined with in situ synchrotron X-ray diffraction. The Clapeyron slope was determined to be −2.5 ± 0.4MPa/K and did not vary significantly with compositions and used pressure scales. Using Pt scales, our data indicate that the postspinel transition occurs in pyrolitic compositions at 23.6–24.5GPa (1850K). The transition pressure and slope are consistent with the depth and topography of the 660 km discontinuity. Our data reveal that inaccuracy in pressure scales alone cannot explain the discrepancy and technical differences between MAP and LHDAC contribute significantly to the discrepancy.
Short Title
Geophys. Res. Lett.