Discussion of 鈥淭he applicability of garnet-orthopyroxene geobarometry in mantle xenoliths鈥? by Wu C.-M. and Zhao G. (Lithos, v. 125, p. 1-9)

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• 作者：Paolo Nimis^a ; ^b ; ^{paolo.nimis@unipd.it} ; Herman Grü ; tter^c
• 关键词：Geobarometry ; Geothermometry ; Mantle xenoliths
• 刊名：Lithos
• 出版年：2012
• 期刊代码：54_00244937
• 类别：ear
• 出版时间：June, 2012
• 卷：142-143
• 期：Complete
• 页码：285-287
• 文件大小：430 K

摘要

Wu and Zhao (2011) argue that pressures and temperatures for mantle xenoliths are best determined by combining Taylor's (1998) garnet-orthopyroxene barometer and two-pyroxene thermometer. Here we show that this choice may lead to grossly erroneous P-T estimates for some peridotitic compositions and increased scatter around xenolith geotherms. We contend that the Nickel and Green (1985) barometer remains a better choice than the Taylor (1998) barometer for thermobarometry of garnet-facies mantle peridotites and pyroxenites, at least for orthopyroxenes with moderate sodium contents. For highly-sodic orthopyroxene compositions, the reliability of the Nickel and Green (1985) barometer and of its modifications proposed by Carswell and Gibb (1987) and Carswell (1991) still awaits detailed evaluation.