Response to a comment by Chun-Ming Wu on “Quantifying the tectono-metamorphic evolution of pelitic rocks from a wide range of tectonic settings: mineral compositions in equilibrium”
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Wu (2009) has commented on aspects of our paper (Caddick and Thompson 2008; hereafter CT08), whose primary purpose was to demonstrate how the coexisting compositions of minerals are highly sensitive to the available buffering assemblage in metamorphic rocks over wide ranges of pressure and temperature (P and T). The concerns of Wu involve (a) the validity of methods used to derive expressions for garnet–biotite (GB) and garnet–plagioclase (GASP) equilibria as a function of P and T, and (b) the performance of these expressions compared to alternative thermobarometer calibrations. In particular, calculation from a large thermodynamic dataset (Holland and Powell 1998) rather than a primary set of reversed equilibrium experiments, and the use of P–T–XPhase relations calculated for a fixed bulk-rock composition are questioned.
CT08 examines the P and Tdependence of particular exchange equilibria and net transfer (continuous) reactions using existing calibrations via published...
KeywordsMineral Composition Kyanite Natural Assemblage Calculate Phase Equilibrium Wide Compositional Range
- Gessmann CK, Spiering B, Raith M (1997) Experimental study of the Fe–Mg exchange between garnet and biotite: constraints on the mixing behavior and analysis of the cation-exchange mechanisms. Am Miner 82:1225–1240Google Scholar
- Hodges KV, McKenna LW (1987) Realistic propagation of uncertainties in geologic thermobarometry. Am Miner 72:671–680Google Scholar
- Holdaway MJ (2000) Application of new experimental and garnet Margules data to the garnet- biotite geothermometer. Am Miner 85:881–892Google Scholar
- Holdaway MJ (2001) Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer. Am Miner 86:1117–1129Google Scholar
- Perchuk LL, Lavrent’eva IV (1983) Experimental investigation of exchange equilibria in the system cordierite–garnet–biotite. In: Saxena SK (ed) Kinetics and equilibrium in mineral reactions, vol 3. Springer, New York, pp 199–239Google Scholar
- Wu C-M (2009) Comment on “Quantifying the tectono-metamorphic evolution of pelitic rocks from a wide range of tectonic settings: mineral compositions in equilibrium” by M.J. Caddick and A.B. Thompson. Contrib Mineral PetrolGoogle Scholar