[IGPP Everyone] Badro geocheminar today at noon
John Wasson
jtwasson at ucla.edu
Tue Feb 10 10:27:10 PST 2015
Geocheminar
Slichter 3843
12 noon, 10 Feb 2015
Dr. James Badro
IPGP (Paris)
Accreting the Earth and forming its core: Experimental and theoretical
constraints.
Terrestrial core formation produced geophysical and geochemical signatures
that remain to this day. Seismology requires incorporation of light elements
in the core, while mantle geochemistry reveals patterns of siderophile
element depletion inherited imposed by the prevailing physiochemical
conditions during core formation. Combining results from petrologic and
geochemical data together with constraints from mineral physics and
seismology, core formation models allow tracking the evolution of mantle and
core composition; I will show that core formation must be restricted to
mid-mantle depth and high temperatures. I will also propose, in contrast to
the current paradigm, that the Earths mantle started more oxidized that it
is at present, and has become reduced through time by oxygen incorporation
in the growing core. This range of conditions producing the observed mantle
abundance of nickel, cobalt, chromium, and vanadium, yield an oxygen-rich
core consistent with seismic observables.
More information: James Badro, Alexander S. Côtéa, and John P. Brodholt
(2014) A seismologically consistent compositional model of Earths core.
PNAS 111, 7545.
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