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Fate of MgSiO₃ melts at core–mantle boundary conditions


Petitgirard, Sylvain ; Malfait, Wim J. ; Sinmyo, Ryosuke ; Kupenko, Ilya ; Hennet, Louis ; Harries, Dennis ; Dane, Thomas ; Burghammer, Manfred ; Rubie, David C.:
Fate of MgSiO₃ melts at core–mantle boundary conditions.
In: Proceedings of the National Academy of Sciences of the United States of America. Bd. 112 (17 November 2015) Heft 46 . - S. 14186-14190.
ISSN 1091-6490
DOI: 10.1073/pnas.1512386112


One key for understanding the stratification in the deep mantle lies in the determination of the density and structure of matter at high pressures, as well as the density contrast between solid and liquid silicate phases. Indeed, the density contrast is the main control on the entrainment or settlement of matter and is of fundamental importance for understanding the past and present dynamic behavior of the deepest part of the Earth’s mantle. Here, we adapted the X-ray absorption method to the small dimensions of the diamond anvil cell, enabling density measurements of amorphous materials to unprecedented conditions of pressure. Our density data for MgSiO3 glass up to 127 GPa are considerably higher than those previously derived from Brillouin spectroscopy but validate recent ab initio molecular dynamics simulations. A fourth-order Birch–Murnaghan equation of state reproduces our experimental data over the entire pressure regime of the mantle. At the core–mantle boundary (CMB) pressure, the density of MgSiO3 glass is 5.48 ± 0.18 g/cm3, which is only 1.6 lower than that of MgSiO3 bridgmanite at 5.57 g/cm3, i.e., they are the same within the uncertainty. Taking into account the partitioning of iron into the melt, we conclude that melts are denser than the surrounding solid phases in the lowermost mantle and that melts will be trapped above the CMB.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Institutionen der Universität: Profilfelder > Advanced Fields > Hochdruck- und Hochtemperaturforschung
Forschungseinrichtungen > Forschungszentren > Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik - BGI
Profilfelder > Advanced Fields
Forschungseinrichtungen > Forschungszentren
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik
500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
Eingestellt am: 18 Mai 2017 09:36
Letzte Änderung: 19 Mai 2017 08:14
URI: https://eref.uni-bayreuth.de/id/eprint/37164