2015年4月
Effect of clinopyroxene composition on Fe-Mg distribution coefficient between garnet and clinopyroxene
JOURNAL OF MINERALOGICAL AND PETROLOGICAL SCIENCES
- ,
- ,
- 巻
- 110
- 号
- 2
- 開始ページ
- 82
- 終了ページ
- 87
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.2465/jmps.141020
- 出版者・発行元
- JAPAN ASSOC MINERALOGICAL SCIENCES
This study examines the effect of jadeite content (Xjd) in omphacite on Fe-Mg distribution coefficient between garnet and clinopyroxene (K-D) by using natural data obtained from ultrahigh-pressure eclogites of the Sulu region, China. A previous study has already pointed out that a negative correlation between lnK(D) and Xjd and a positive correlation between Fe# [=Fe2+/(Fe2++Mg)] of omphacite and Xjd are present. On the other hand, this study newly recognized that KD decreases with decreasing Ca + Na + K contents in M2 site of omphacite, indicating that excess Fe2+ may be incorporated into M2 site of omphacite with decreasing Ca + Na + K contents and hence total Fe# values of omphacite may become excessively high. Thus, application of garnet-clinopyroxene geothermometer for omphacite with significant amount of jadeite and/or ferrosilite (and enstatite) components may overestimate the peak metamorphic temperatures in some cases. As a first approximation, it is better to avoid the use of omphacite with Ca + Na + K contents significantly lower than 1.0 a.p.f.u. for the application of garnet-clinopyroxene geothermometer.
- リンク情報
- ID情報
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- DOI : 10.2465/jmps.141020
- ISSN : 1345-6296
- eISSN : 1349-3825
- Web of Science ID : WOS:000357672800006