Application of INVEQ to the geothermobarometry of metamorphic rocks near a kyanite-sillimanite isograd, Mica Creek, British Columbia
-
Edward D. Ghent
and
Terence M. Gordon
Abstract
A kyanite-sillimanite isograd is well-exposed in the Mica Creek area, British Columbia, and both pelitic and basic rocks occur within a few hundred meters of the isograd. This provides us with an opportunity to test geothermobarometry in pelitic and basic bulk compositions against an independent metamorphic equilibrium, kyanite-sillimanite. The kyanite-sillimanite isograd is modeled by a univariant P-T curve that passes through the following points (T °C, P kbar): 564/5; 610/6; 656/7; and 796/10. The quoted experimental uncertainty is 25 °C or about 350 J in ΔG. Samples that bracket the kyanite-sillimanite isograd in the Mica Creek area have the following mineral assemblages: quartzmuscovite- biotite-garnet-plagioclase-kyanite or sillimanite in pelitic rocks; and hornblende-plagioclase- clinopyroxene-garnet-quartz in basic rocks. Using the thermodynamic database of Berman (1988) and the INVEQ program of Gordon (1992), we have calculated metamorphic pressures and temperatures for 17 samples that bracket the kyanite-sillimanite isograd.
For the basic rocks, the P-T estimate fell entirely within the kyanite stability field, even for samples containing sillimanite, and the 68.3% confidence region overlapped the ±25 °C uncertainty in the kyanite-sillimanite P-T curve. For the pelitic rocks, the P-T estimate and the 68.3% confidence region usually fell within the sillimanite stability field and the confidence region overlapped the ±25 °C uncertainty in the kyanite-sillimanite P-T curve.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Eclogite-facies relics and inferred ultrahigh-pressure metamorphism in the North Dabie Complex, central-eastern China
- Application of INVEQ to the geothermobarometry of metamorphic rocks near a kyanite-sillimanite isograd, Mica Creek, British Columbia
- Microstructural characterization of metamorphic magnetite crystals with implications for oxygen isotope distribution
- Coexisting monazite and allanite in peraluminous granitoids of the TribečMountains, Western Carpathians
- Effect of alkalis, phosphorus, and water on the surface tension of haplogranite melt
- Direct observation of immiscibility in pyrope-almandine-grossular garnet
- On the cluster analysis of grains and crystals in rocks
- Experimental approach to constrain second critical end points in fluid/silicate systems: Near-solidus fluids and melts in the system albite-H2O
- Estimation and testing of standard molar thermodynamic properties of tourmaline end-members using data of natural samples
- An investigation of matrix effects in the analysis of fluorine in humite-group minerals by EMPA, SIMS, and SREF
- New data on the crystal-chemistry of fluoborite by means of SREF, SIMS, and EMP analysis
- Effect of aluminum on Ti-coordination in silicate glasses: A XANES study
- XAFS study of Cu model compounds and Cu2+ sorption products on amorphous SiO2, γ-Al2O3, and anatase
- Oxidation-reduction mechanism of iron in dioctahedral smectites: I. Crystal chemistry of oxidized reference nontronites
- Oxidation-reduction mechanism of iron in dioctahedral smectites: II. Crystal chemistry of reduced Garfield nontronite
- 15N NMR study of nitrate ion structure and dynamics in hydrotalcite-like compounds
- 29Si and 27Al MAS-NMR spectroscopy of b-eucryptite (LiAlSiO4): The enthalpy of Si,Al ordering
- The nuclear and magnetic structure of “white rust”—Fe(OH0.86D0.14)2
- In-situ study of the R3̅ to R3̅c phase transition in the ilmenite-hematite solid solution using time-of-flight neutron powder diffraction
- In situ X-ray diffraction investigation of lawsonite and zoisite at high pressures and temperatures
- A shell model for the simulation of rhombohedral carbonate minerals and their point defects
- Optical properties of natural and cation-exchanged heulandite group zeolites
- The crystal structure of gearksutite, CaAlF4(OH)· H2O
- A new anhydrous amphibole from the Eifel region, Germany: Description and crystal structure of obertiite, NaNa2(Mg3Fe3+Ti4+)Si8O22O2
- Kinoshitalite, Ba(Mg)3(Al2Si2)O10(OH,F)2, a brittle mica from a manganese deposit in Oman: Paragenesis and crystal chemistry
- The crystal structure of parisite-(Ce), Ce2CaF2(CO3)3
- High-pressure synthesis of Na2Mg6Si6O18(OH)2—a new hydrous silicate phase isostructural with aenigmatite
