期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
卷 120, 期 11, 页码 7460-7489出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2015JB012108
关键词
-
资金
- National Science Foundation [CSEDI EAR-1161046, EAR-0956166]
- Turner Postdoctoral Fellowship at the University of Michigan
- National Science Foundation-Earth Sciences [EAR-1128799]
- Department of Energy-Geosciences [DE-FG02-94ER14466]
- U.S. D.O.E. [DE-AC02-06CH11357]
- COMPRES under NSF [EAR 11-57758]
- Division Of Earth Sciences
- Directorate For Geosciences [0956166] Funding Source: National Science Foundation
The high-pressure/high-temperature equation of state (EOS) of synthetic 13% Fe-bearing bridgmanite (Mg silicate perovskite) is measured using powder X-ray diffraction in a laser-heated diamond anvil cell with a quasi-hydrostatic neon pressure medium. We compare these results, which are consistent with previous 300 K sound speed and compression studies, with a reanalysis of Fe-free Mg end-member data from Tange et al. (2012) to determine the effect of iron on bridgmanite's thermoelastic properties. EOS parameters are incorporated into an ideal lattice mixing model to probe the behavior of bridgmanite at deep mantle conditions. With this model, a nearly pure bridgmanite mantle composition is shown to be inconsistent with density and compressibility profiles of the lower mantle. We also explore the buoyant stability of bridgmanite over a range of temperatures and compositions expected for Large Low-Shear Velocity Provinces, concluding that bridgmanite-dominated thermochemical piles are more likely to be passive dense layers externally supported by convection, rather than internally supported metastable domes. The metastable dome scenario is estimated to have a relative likelihood of only 4-7%, given the narrow range of compositions and temperatures consistent with seismic constraints. If buoyantly supported, such structures could not have remained stable with greater thermal contrast early in Earth's history, ruling out formation scenarios involving a large concentration of heat producing elements.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据