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Investigating Magma Ocean Solidification on Earth Through Laser‐Heated Diamond Anvil Cell Experiments
Author(s) -
Nabiei Farhang,
Badro James,
Boukaré CharlesÉdouard,
Hébert Cécile,
Cantoni Marco,
Borensztajn Stephan,
Wehr Nicolas,
Gillet Philippe
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092446
Subject(s) - silicate perovskite , geology , crystallization , silicate , mantle (geology) , fractional crystallization (geology) , mineralogy , phase diagram , geochemistry , materials science , phase (matter) , thermodynamics , chemical engineering , chemistry , physics , organic chemistry , engineering
We carried out a series of silicate fractional crystallization experiments at lower mantle pressures using the laser‐heated diamond anvil cell. Phase relations and the compositional evolution of the cotectic melt and equilibrium solids along the liquid line of descent were determined and used to assemble the melting phase diagram. In a pyrolitic magma ocean, the first mineral to crystallize in the deep mantle is iron‐depleted calcium‐bearing bridgmanite. From the phase diagram, we estimate that the initial 33%–36% of the magma ocean will crystallize to form such a buoyant bridgmanite. Substantial calcium solubility in bridgmanite is observed up to 129 GPa, and significantly delays the crystallization of the calcium silicate perovskite phase during magma ocean solidification. Residual melts are strongly iron‐enriched as crystallization proceeds, making them denser than any of the coexisting solids at deep mantle conditions, thus supporting the terrestrial basal magma ocean hypothesis (Labrosse et al., 2007).