Metamorphism and phase relations in carbonate rocks from the Nevado-Filábride Complex (Cordilleras Béticas, Spain): application of the Ttn + Rt + Cal + Qtz + Gr buffer |
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| Authors: | V López Sánchez-Vizcaíno J A D Connolly M T Gómez-Pugnaire |
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| Institution: | (1) Departamento de Geología, Universidad de Jaén, Escuela Universitaria Politécnica, Calle Alfonso X el Sabio 28, E-23700 Linares, Spain, ES;(2) Institut für Mineralogie und Petrographie, ETH Zentrum, Sonneggstrasse 5, CH-8092 Zürich, Switzerland, CH;(3) Departamento de Mineralogía y Petrología, Universidad de Granada, Avda Fuentenueva s/n, E-18002 Granada, Spain, ES |
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| Abstract: | Phase relations and metamorphic conditions have been studied in metacarbonate rocks from the Nevado-Filábride Complex (Cordilleras
Béticas) through forward modeling. In many rock samples, the assemblage titanite + rutile + calcite + quartz + graphite buffered
the composition of the C-O-H fluid present during metamorphism. Over a wide range of P-T conditions, fluid compositions computed for this buffer are essentially binary H2O-CO2 mixtures. This buffer also constrains the chemical potentials of TiO2, CaO and SiO2. Consequently it is possible to make a thermodynamic projection through these components to predict the stable phase relations
consistent with the buffer. Using this method, phase relations have been analyzed in a rock containing the buffer assemblage
and paragonite, albite, phengite, epidote, and chlorite. The equilibrium P-T conditions for this assemblage are constrained, by minimization of the differences between predicted and observed mineral
compositions, to be 560 ± 15 °C and 9.5 ± 1 kbar. Conditions obtained compare well with those estimated from other studies
in different lithologic units. The inferred metamorphic fluid composition is H2O-rich ().
Received: 11 October 1995 / Accepted 5 August 1996 |
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