Jump to ContentJump to Main Navigation
Show Summary Details
More options …

American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian


IMPACT FACTOR 2017: 2.645

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

Online
ISSN
1945-3027
See all formats and pricing
More options …
Volume 92, Issue 10

Issues

A monazite oxygen isotope thermometer

Dan O. Breecker
  • Corresponding author
  • Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, U.S.A.
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Zachary D. Sharp
  • Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, U.S.A.
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2015-04-01 | DOI: https://doi.org/10.2138/am.2007.2367

Abstract

A quartz-monazite oxygen isotope thermometer was calibrated based on δ18O measurements of mineral separates from monazite-bearing rocks and on piston cylinder calcite-monazite oxygen exchange experiments. The oxygen isotope composition of monazite was measured using secondary ion mass spectrometry (SIMS) and multiple fluorination techniques. The results of these measurements suggest that (1) differences in Th content of monazite can cause the instrumental mass fractionation in an ion microprobe to vary by at least 4‰; (2) the oxygen isotope compositions of chemically distinct zones in the monazite grains analyzed are probably similar; and (3) δ18Omnz is most accurately determined by extracting oxygen via fluorination in nickel vessels. Comparing the oxygen isotope fractionation between quartz and monazite with independently derived temperature estimates suggests that (1) the coefficient of fractionation between quartz and monazite (aqtz-mnz) equals 2.2 ± 0.6, and (2) ~100 μm monazite grains in a multiply metamorphosed, granulite facies orthogneiss from the Wind River Range record the high-temperature history of this rock, whereas other isotopic thermometers suffered retrograde oxygen exchange. This evidence indicates that monazite might be used to constrain peak metamorphic temperatures, which may correlate with the ages recorded by the same mineral.

Keywords: Monazite; oxygen isotope; thermometry; ion probe; Wind River Range

About the article

Received: 2006-06-26

Accepted: 2007-05-11

Published Online: 2015-04-01

Published in Print: 2007-10-01


Citation Information: American Mineralogist, Volume 92, Issue 10, Pages 1561–1572, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am.2007.2367.

Export Citation

© 2015 by Walter de Gruyter Berlin/Boston.Get Permission

Comments (0)

Please log in or register to comment.
Log in