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The amphibolite‐granulite facies transition in West Uusimaa, S.W. Finland. A fluid inclusion study
Author(s) -
SCHREURS J.
Publication year - 1984
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.1984.tb00593.x
Subject(s) - granulite , metamorphism , geology , metamorphic facies , facies , geochemistry , metamorphic rock , fluid inclusions , inclusion (mineral) , petrology , geomorphology , mineralogy , paleontology , quartz , structural basin
This work presents the results of a fluid inclusion study of an amphibolite‐granulite facies transition in West Uusimaa, S.W. Finland. Early fluid‐inclusions in the granulite facies area are characteristically carbonic (CO 2 ), in contrast to predominantly aqueous early inclusions in the amphibolite facies area. These early inclusions can be related to peak metamorphic conditions (750‐820°C and 3‐5 kbar for peak granulite facies metamorphism). Relatively young CO 2 inclusions with low densities (<0.8g/cm 3 ) indicate that the first part of the cooling history of the rocks was characterized by a near isothermal uplift. N 2 ‐CH 4 inclusions, with compositions ranging between pure CH 4 and pure N 2 (Raman spectral analysis), were found in the whole area. They are probably syn‐ or even pre‐early inclusions. Only nearly critical homogenizing inclusions have been found (low density). Pressure estimates, based on densities of early fluid inclusions, show that the rapid transition of amphibolite towards granulite facies metamorphism is virtually isobaric. Granulite facies metamorphism in West Uusimaa is a thermal event, probably induced by the influx of hot, CO 2 ‐bearing fluids.