High-density CO2−N2 inclusions in eclogite-facies metasediments of the Münchberg gneiss complex, SE Germany

Autor: Reiner Klemd, E. E. Horn, A. M. van den Kerkhof
Rok vydání: 1992
Předmět:
Zdroj: Contributions to Mineralogy and Petrology. 111:409-419
ISSN: 1432-0967
0010-7999
DOI: 10.1007/bf00311200
Popis: The eclogite-facies metasedimentary rocks in the Munchberg gneiss complex (T=630±30° C/P≥17–24 kbar) locally contain CO2−N2-rich fluid inclusions of extremely low molar volumes (32 cm3/mol) in quartz. These fluid compositions are mainly found in rocks intercalated with calcsilicate bands. Densities were determined from low-temperature phase transitions like stable or metastable homogenization (L+V→L), partial homogenization (S+L+V→S+L) and the transition S+L→L (L = liquid, V = vapour, S = solid). The high fluid densities are in agreement with eclogite-facies pressure and temperature and subsequent amphibolite facies. CO2−N2 inclusions were not observed in adjacent eclogites nor in non-calcareous metasediments. These rock types contain predominantly H2O-rich inclusions correlating with amphibolite-facies conditions. The variation of fluid composition with lithological differences indicates local fluid gradients and speaks against a pervasive fluid flow during eclogite-facies metamorphism.
Databáze: OpenAIRE
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