HR: 1340h
AN: MR23A-0046    [Abstracts]
TI: Iron-magnesium alloy in the Earth's Core
AU: * Dubrovinskaia, N
EM: Natalia.Dubrovinskaia@uni-bayreuth.de
AF: Bayerisches Geoinstitut, Universit„t Bayreuth, Bayreuth, 95440 Germany
AU: Dubrovinsky, L
EM: Leonid.Dubrovinsky@uni-bayreuth.de
AF: Bayerisches Geoinstitut, Universit„t Bayreuth, Bayreuth, 95440 Germany
AU: Abrikosov, I
EM: Igor.Abrikosov@lin.se
AF: Department of Physics and Measurement Technology, Link”pings University, Link”ping, 751 21 Sweden
AB: Composition of the Earth's outer core is a geochemical parameter crucial for understanding the evolution and current dynamics of our planet. Since it was recognized that the liquid metallic outer core is about 10% less dense than pure iron, different elements lighter than iron, including Si, S, O, C, and H, were proposed as major or at least significantly abundant in Earth's core. However, combination of experimental results with theoretical and geochemical considerations shows that it is unlikely that any one of these elements can account for the density deficit on its own. In series of experiments in a multianvil apparatus and in electrically- and laser-heated diamond anvil cells, we demonstrate that high pressure promotes solubility of magnesium in iron and at megabar pressure range more than 10 at% of Mg can dissolve in Fe. At pressures above 95 to 100 GPa, molten iron reacts with periclase MgO forming an iron-magnesium alloy and iron oxide. Our observations suggest that magnesium can be an important light element in Earth's outer core, but it cannot account for the seismologically determined density deficit on its own.
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
DE: 3672 Planetary mineralogy and petrology (5410)
DE: 3909 Elasticity and anelasticity
DE: 3924 High-pressure behavior
DE: 3929 NMR, Mossbauer spectroscopy, and other magnetic techniques
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005