Estimates of the Light Element Content of the Earth's Core From Models of Core Formation

Details Estimates of the Light Element Content of the Earth's Core From Models of Core Formation Estimates of the Light Element Content of the Earth's Core From Models of Core Formation

Dec 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufmmr31b..01r&link_type=abstract

American Geophysical Union, Fall Meeting 2008, abstract #MR31B-01

Physics

1015 Composition Of The Core, 3924 High-Pressure Behavior, 8125 Evolution Of The Earth (0325), 8147 Planetary Interiors (5430, 5724, 6024)

Scientific paper

It has been known for many years that the Earth's metallic Fe-Ni core contains up to 10-12 wt% light elements, with possible candidates being S, O, Si, C, N, and H. Because chemical interaction with the mantle has been very limited during Earth's history, the light element content is expected to have been established during core formation. We estimate the concentrations of oxygen and silicon in the core through a new multi- stage model of core formation that is constrained by the concentrations of both siderophile and lithophile elements in the Earth's mantle. The Earth accretes through a series of collisions with smaller planetary bodies that had already differentiated at low pressure (e.g. <1 GPa). Each impact results in a magma ocean in which the core of the impactor reequilibrates with silicate liquid at pressures that increase during accretion, e.g. from 3 to 90 GPa, before merging with the Earth's proto-core. The bulk compositions of the proto-Earth and impactors are chondritic with oxidation states (i.e. bulk oxygen contents) that can be varied. The compositions of coexisting liquid metal and liquid silicate in the magma ocean are determined by a mass balance calculation that is based on experimental determinations of the metal-silicate partitioning of FeO and Si, together with a range of trace elements including Ni, Co, V, Cr, Ta and Nb. Models that reproduce mantle geochemistry best involve heterogeneous accretion in which the oxygen content of the accreting material increases - which causes oxygen fugacity to increase significantly as the Earth grows. In addition, the final giant impacts involve only partial reequilibration of metal and silicate at high pressure (e.g. due to incomplete emulsification of the impactor cores). Current results indicate that both O and Si are present in the core in sub-equal concentrations (e.g. 2-3 wt% O and ~5 wt% Si). Together with approximately 2 wt% S, these concentrations are sufficient to satisfy recent estimates of the density deficit.

Affiliated with

Also associated with

No associations

Rating

Estimates of the Light Element Content of the Earth's Core From Models of Core Formation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Estimates of the Light Element Content of the Earth's Core From Models of Core Formation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Estimates of the Light Element Content of the Earth's Core From Models of Core Formation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1242561