New Mössbauer measurements of Fe 3+/ΣFe in chromites from the mantle section of the Oman ophiolite

Evidence for the oxidation of the sub-oceanic mantle

H. Rollinson, J. Adetunji, A. A. Yousif, A. M. Gismelseed

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Room temperature Mössbauer and electron-probe measurements of Fe 3+/ΣFe in chromite from the mantle section of the Oman ophiolite define two groups of samples: a low Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.21-0.36) have cr# = Cr/(Cr + Al) in the range 0.49-0.75, whereas a smaller more geographically localized high Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.71-0.78) have a more restricted range of cr# ratios of 0.72-0.75. The low Fe 3+/ΣFe chromitites have very variable Fe 3+/ΣFe ratios. They are thought to have crystallized from melts that have interacted with depleted mantle and thereby acquired their variable Fe 3+/ ΣFe ratio. The high Fe 3+/ΣFe chromitites are restricted to one small area of the mantle and their high oxidation state is thought to be post magmatic. They are either the product of later heating, related to melt flux or interaction with a later oxidising melt. A difference in oxygen fugacity between the MORB-depleted harzburgite host, which is at the quartz-fayalite-magnetite (QFM) buffer and the later chromite-bearing melts (QFM + 2) implies that there is a real difference in the oxidation state of the MORB and arc-magma sources.

Original languageEnglish
Pages (from-to)579-596
Number of pages18
JournalMineralogical Magazine
Volume76
Issue number3
DOIs
Publication statusPublished - 2012

Fingerprint

Ferrosoferric Oxide
Chromite
Quartz
chromite
ophiolite
Bearings (structural)
melt
mantle
oxidation
Oxidation
fayalite
mid-ocean ridge basalt
magnetite
Buffers
Oxygen
Fluxes
quartz
Heating
harzburgite
Electrons

Keywords

  • chromite
  • chromitite
  • iron oxidation state
  • mantle rocks
  • Mössbauer spectrometry
  • Oman ophiolite
  • spinel

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

New Mössbauer measurements of Fe 3+/ΣFe in chromites from the mantle section of the Oman ophiolite : Evidence for the oxidation of the sub-oceanic mantle. / Rollinson, H.; Adetunji, J.; Yousif, A. A.; Gismelseed, A. M.

In: Mineralogical Magazine, Vol. 76, No. 3, 2012, p. 579-596.

Research output: Contribution to journalArticle

@article{4b7b070a0cbb4aec887fabdfa9a1ea85,
title = "New M{\"o}ssbauer measurements of Fe 3+/ΣFe in chromites from the mantle section of the Oman ophiolite: Evidence for the oxidation of the sub-oceanic mantle",
abstract = "Room temperature M{\"o}ssbauer and electron-probe measurements of Fe 3+/ΣFe in chromite from the mantle section of the Oman ophiolite define two groups of samples: a low Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.21-0.36) have cr# = Cr/(Cr + Al) in the range 0.49-0.75, whereas a smaller more geographically localized high Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.71-0.78) have a more restricted range of cr# ratios of 0.72-0.75. The low Fe 3+/ΣFe chromitites have very variable Fe 3+/ΣFe ratios. They are thought to have crystallized from melts that have interacted with depleted mantle and thereby acquired their variable Fe 3+/ ΣFe ratio. The high Fe 3+/ΣFe chromitites are restricted to one small area of the mantle and their high oxidation state is thought to be post magmatic. They are either the product of later heating, related to melt flux or interaction with a later oxidising melt. A difference in oxygen fugacity between the MORB-depleted harzburgite host, which is at the quartz-fayalite-magnetite (QFM) buffer and the later chromite-bearing melts (QFM + 2) implies that there is a real difference in the oxidation state of the MORB and arc-magma sources.",
keywords = "chromite, chromitite, iron oxidation state, mantle rocks, M{\"o}ssbauer spectrometry, Oman ophiolite, spinel",
author = "H. Rollinson and J. Adetunji and Yousif, {A. A.} and Gismelseed, {A. M.}",
year = "2012",
doi = "10.1180/minmag.2012.076.3.09",
language = "English",
volume = "76",
pages = "579--596",
journal = "Mineralogical Magazine",
issn = "0026-461X",
publisher = "Mineralogical Society",
number = "3",

}

TY - JOUR

T1 - New Mössbauer measurements of Fe 3+/ΣFe in chromites from the mantle section of the Oman ophiolite

T2 - Evidence for the oxidation of the sub-oceanic mantle

AU - Rollinson, H.

AU - Adetunji, J.

AU - Yousif, A. A.

AU - Gismelseed, A. M.

PY - 2012

Y1 - 2012

N2 - Room temperature Mössbauer and electron-probe measurements of Fe 3+/ΣFe in chromite from the mantle section of the Oman ophiolite define two groups of samples: a low Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.21-0.36) have cr# = Cr/(Cr + Al) in the range 0.49-0.75, whereas a smaller more geographically localized high Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.71-0.78) have a more restricted range of cr# ratios of 0.72-0.75. The low Fe 3+/ΣFe chromitites have very variable Fe 3+/ΣFe ratios. They are thought to have crystallized from melts that have interacted with depleted mantle and thereby acquired their variable Fe 3+/ ΣFe ratio. The high Fe 3+/ΣFe chromitites are restricted to one small area of the mantle and their high oxidation state is thought to be post magmatic. They are either the product of later heating, related to melt flux or interaction with a later oxidising melt. A difference in oxygen fugacity between the MORB-depleted harzburgite host, which is at the quartz-fayalite-magnetite (QFM) buffer and the later chromite-bearing melts (QFM + 2) implies that there is a real difference in the oxidation state of the MORB and arc-magma sources.

AB - Room temperature Mössbauer and electron-probe measurements of Fe 3+/ΣFe in chromite from the mantle section of the Oman ophiolite define two groups of samples: a low Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.21-0.36) have cr# = Cr/(Cr + Al) in the range 0.49-0.75, whereas a smaller more geographically localized high Fe 3+/ΣFe group (with Fe 3+/ΣFe = 0.71-0.78) have a more restricted range of cr# ratios of 0.72-0.75. The low Fe 3+/ΣFe chromitites have very variable Fe 3+/ΣFe ratios. They are thought to have crystallized from melts that have interacted with depleted mantle and thereby acquired their variable Fe 3+/ ΣFe ratio. The high Fe 3+/ΣFe chromitites are restricted to one small area of the mantle and their high oxidation state is thought to be post magmatic. They are either the product of later heating, related to melt flux or interaction with a later oxidising melt. A difference in oxygen fugacity between the MORB-depleted harzburgite host, which is at the quartz-fayalite-magnetite (QFM) buffer and the later chromite-bearing melts (QFM + 2) implies that there is a real difference in the oxidation state of the MORB and arc-magma sources.

KW - chromite

KW - chromitite

KW - iron oxidation state

KW - mantle rocks

KW - Mössbauer spectrometry

KW - Oman ophiolite

KW - spinel

UR - http://www.scopus.com/inward/record.url?scp=84863516351&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84863516351&partnerID=8YFLogxK

U2 - 10.1180/minmag.2012.076.3.09

DO - 10.1180/minmag.2012.076.3.09

M3 - Article

VL - 76

SP - 579

EP - 596

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 3

ER -