[IGPP Everyone] Badro geocheminar

[John Wasson]

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 Earth’s 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 Earth’s core.
PNAS 111, 7545.

 

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