Reassessment of the garnet-clinopyroxene Fe−Mg exchange thermometer: II. Thermodynamic analysis

Berman, R G; Aranovich, L. Ya.; Pattison, David R.M.

doi:10.1007/bf00310715

Cited by 148 publications

(76 citation statements)

References 34 publications

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“…The temperature and pressure ranges of 760810 °C and 11.5 13.4 kbars calculated on the basis of garnet-pyroxene geothermometer (Ravna 2000) and garnet-plagioclaseamphibole-quartz geobarometer (Kohn Spear 1990) correspond to high-grade conditions of metamorphic equilibration. The temperatures estimated using Ravna (2000) calibration do not show large deviations from previous calibrations (e. g. Ellis Green 1979, Powell 1985, Ai 1992, Berman et al 1995 and are regarded as more accurate for a large compositional range of rocks (Ravna 2000). Only ten percent of analyzed garnet-clinopyroxene pairs (only from the rims of grains) were found suitable for this geothermometer and results in the above mentioned relatively broad range of calculated temperatures.…”

Section: Holice Skarn Localitymentioning

confidence: 73%

Three types of skarn in the northern part of the Moldanubian zone, Bohemian Massif - Implications for their origin

Drahota¹,

Pertold²,

Pudilová³

2012

J. Geosci.

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Section: Holice Skarn Localitymentioning

confidence: 73%

Three types of skarn in the northern part of the Moldanubian zone, Bohemian Massif - Implications for their origin

Drahota¹,

Pertold²,

Pudilová³

2012

J. Geosci.

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“…Since the proposal of the prototype geothermometer by Råheim and Green (1974), many researchers have recalibrated the garnet-clinopyroxene geothermometer, by mainly introducing non-ideal terms for variations in garnet composition (e.g., Ellis and Green, 1979, Powell, 1985, Pattison and Newton, 1989, Ai, 1994, Ganguly et al, 1996, Krogh-Ravna, 2000, Nakamura, 2009). However, the effect of changes in clinopyroxene composition on distribution coefficient between garnet and clinopyroxene (K D ) has not been paid much attention in these calibrations except for a few works (e.g., Berman et al, 1995). However, Hirajima (1996), based on the data from ultrahigh-pressure (UHP) eclogites collected from Yangkou area of the Sulu region of eastern China, pointed out that the apparent temperatures calculated from the geothermometer (Powell, 1985) increased from about 600°C to 900°C with an increase in jadeite content (Xjd) in omphacite from about 0.50 to 0.75, which was caused by an increase of Fe# [= Fe 2+ /(Fe 2+ + Mg)] in omphacite along with Xjd.…”

Section: Introductionmentioning

confidence: 99%

Effect of clinopyroxene composition on Fe–Mg distribution coefficient between garnet and clinopyroxene

Nakamura

Okada

Hirajima

2015

Journal of Mineralogical and Petrological Sciences

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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# [= Fe 2+ /(Fe 2+ + Mg)] of omphacite and Xjd are present. On the other hand, this study newly recognized that K D decreases with decreasing Ca + Na + K contents in M2 site of omphacite, indicating that excess Fe 2+ 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 garnetclinopyroxene 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.

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“…The metamorphic P-T conditions were determined by multi-equilibria computation using the thermodynamic data of Berman (1988), Berman et al (1995), and Berman and Aranovich (1996) for end-member phases. The activity models of garnet, plagioclase, amphibole, clinopyroxene, and biotite used in this multi-equilibrium approach were from Berman (1990), Fuhrman andLindsley (1988), Mäder et al (1994), Berman et al (1995), andBerman et al (2007), respectively. For a given assemblage, good convergence of equilibria curves suggests equilibrium among minerals, whereas divergence suggests that one or more phases were improperly involved in the assemblage (e.g., G.C.…”

Section: Multi-equilibria Geothermobarometry: Twq Computationmentioning

confidence: 99%

Metamorphic evolution and geochronology of the tectonic mélange of the Dongbatu and Mogutai blocks, middle Dunhuang orogenic belt, northwestern China

Wang

Zhang

et al. 2018

Geosphere

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Mafic granulite and amphibolite in the Dongbatu and Mogutai blocks, middle Dunhuang orogenic belt, northwest China, southernmost Central Asian orogenic belt, occur as lenses within the matrix of metapelite and marble, exhibiting typical block-in-matrix fabrics of tectonic mélange. Three stages of metamorphic mineral assemblages were identified in these lenses. Clockwise metamorphic pressure-temperature (P-T) paths were obtained through geothermobarometry and thermodynamic pseudosection modeling, passing from 656 °C and 10.9 kbar through 830 °C and 16.5 kbar to 657 °C and 4.9 kbar for the mafic granulite, and from 564-645 °C and 3.2-9.6 kbar through 634-727 °C and 6.1-14.2 kbar to 615-664 °C and 3.2-4.2 kbar for the amphibolites, respectively. Metamorphic peak P-T conditions in the metapelitic country rocks were estimated to be 635-675 °C and 6.0-6.9 kbar. The metamorphic peak of the mafic granulite approaches the high P-T facies series, indicative of a subduction zone. Secondary-ion mass spectrometry and laser ablationinductively coupled plasma-mass spectrometry U-Pb dating of metamorphic zircons suggests that the metamorphic event occurred between ca. 420 and 372 Ma. These data further certify that the subduction of the continental margin and subsequent uplift of the Dunhuang orogenic belt represent a longlived tectono-metamorphic event in the Paleozoic.

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Reassessment of the garnet-clinopyroxene Fe−Mg exchange thermometer: II. Thermodynamic analysis

Cited by 148 publications

References 34 publications

Three types of skarn in the northern part of the Moldanubian zone, Bohemian Massif - Implications for their origin

Three types of skarn in the northern part of the Moldanubian zone, Bohemian Massif - Implications for their origin

Effect of clinopyroxene composition on Fe–Mg distribution coefficient between garnet and clinopyroxene

Metamorphic evolution and geochronology of the tectonic mélange of the Dongbatu and Mogutai blocks, middle Dunhuang orogenic belt, northwestern China

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