Oxidation state of the upper mantle beneath the northwestern part of the Arabian lithosphere

Sobhi Nasir, Ibrahim Abu-Aljarayesh, Sami Mahmood, Abdel Fatah Lehlooh

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Abstract

The Fe3+ contents of spinels from upper mantle lherzolite xenoliths occurring in the Pleistocene alkali basalts of northeast Jordan have been determined using 57Fe Mössbauer spectroscopy at room temperature. The determined Fe3+ fractions were used to calculate oxygen fugacity. The calculated f{hook}O2-T-P conditions are consistent with derivation of the lherzolite samples from a relatively oxidized source region dominated by CO2 and/or H2O fluid species. Calculated f{hook}O2's range from 0.5 above to 1.1 log-units below the fayalite-magnetite-quartz (FMQ) buffer. Estimated Fe3+ Fetotal-ratios from microprobe analyses are 2-7% more than those determined from Mössbauer spectroscopy and can shift the computed oxygen fugacity by 0.1 to 0.6 log-units. Pressure and/or temperature does not contribute significantly in the calculated Δf{hook}O2. The average Δf{hook}O2 (relative to FMQ) is -0.29 ± 0.4 log-units. This is higher than that reported for western Europe (-0.89 ± 0.58), British Columbia (-1.05 ± 0.3), and eastern Australia (-1.78 ± 0.66).

Original languageEnglish
Pages (from-to)359-366
Number of pages8
JournalTectonophysics
Volume213
Issue number3-4
DOIs
Publication statusPublished - Nov 15 1992

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ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geophysics

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