Upper mantle oxygen fugacity recorded by spinel lherzolites

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Authors:Mattioli, Glen S.; Wood, Bernard J.
Author Affiliations:Primary:
Northwest. Univ., Dep. Geol. Sci., Evanston, IL, United States
Volume Title:Nature (London)
Source:Nature (London), 322(6080), p.626-628. Publisher: Macmillan Journals, London, United Kingdom. ISSN: 0028-0836
Publication Date:1986
Note:In English. 32 refs.; illus.
Summary:The oxygen fugacity fO2 was obtained for spinel-lherzolite xenoliths entrained in alkaline magmas, by calibrating the activity of the magnetite component in MgAl2O4-rich synthetic spinel, and applying the data to calculate the thermobarometric fO2 for the three-phase assemblage: olivine-orthopyroxene-spinel. The results for appropriate model xenolith compositions corrected to 15 kbar total P, and plotted in T-fO2 space, fall at or above the synthetic quartz-fayalite-magnetite buffer. The shallow upper mantle does not retain an fO2 signature of equilibrium with the metallic core, and gaseous species in the C-H-O system will be dominated by CO2 and H2O rather than by CH4 and H2. [R.K.H.]
Subjects:Alkalic composition; Experimental studies; Fugacity; Geochemistry; Igneous rocks; Inclusions; Magmas; Mantle; Oxygen; P-T conditions; Peridotites; Phase equilibria; Plutonic rocks; Spinel lherzolite; Ultramafics; Upper mantle; Xenoliths
Abstract Numbers:87M/0915
Record ID:1987005484
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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