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Isotopic signature of core-derived SiO (sub 2)

George Helffrich, Anat Shahar and Kei Hirose
Isotopic signature of core-derived SiO (sub 2)
American Mineralogist (July 2018) 103 (7): 1161-1164


We apply an experimentally based thermodynamic model of Si+O saturation for the core to determine the saturation level of these elements under the conditions when the core formed. The model limits the bulk Si content of the core to between 0.4 and 3.1 wt% depending on the pressure, temperature, and oxygen content of the metal when it segregated from silicate. With knowledge of the core's Si content, the measured (super 30) Si content of the silicate Earth, and the experimentally determined metal-silicate fractionation factor, we can calculate the core's delta (super 30) Si, which is between -0.92 to -1.36 ppm. SiO (sub 2) cycled through the core and then released into the mantle might be trapped in inclusions in diamond formed in the lower mantle. These would be characterized by significantly lighter delta (super 30) Si values of -1.12 + or - 0.13 ppm (1sigma ), compared to bulk silicate earth values of -0.29 ppm and a potentially key indicator of mass transfer from the core to the mantle.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 103
Serial Issue: 7
Title: Isotopic signature of core-derived SiO (sub 2)
Affiliation: Tokyo Institute of Technology, Earth-Life Science Institute, Tokyo, Japan
Pages: 1161-1164
Published: 201807
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 37
Accession Number: 2018-083832
Categories: Isotope geochemistrySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: Carnegie Institution for Science, USA, United StatesUniversity of Tokyo, JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201821
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