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Biotite solid-solutions are a significant H 2 O reservoir in the lithosphere, and the assemblage BtϩOpxϩKfsϩQtz is commonly used to estimate a in high-grade metamorphic H O 2

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The paper distinguishes two complexes of high-grade metamorphic rocks in the central portion of the Kola Peninsula (Baltic Shield): 1) the Vyezhe Tundra complex, mainly enderbites and basic granulites with subordinate plagiogneisses, iron formation, and metapyroxenites, and 2) the Kola series (mainly plagiogneisses with subordinate iron formation and basic granulites). Textural and paragenetic relationships point toward multi-cyclic metamorphism in the region. Metamorphic temperature conditions were estimated using a consistent system of geothermometers and geobarometers. Temperature maxima (670, 565 and 500° C) were obtained, which correspond to different stages of metamorphism in the region. The results show that metamorphism in the two sequences occurred at similar temperatures; furthermore, no differences were found between unsheared and sheared rocks. The findings support the view that equilibration between minerals during metamorphism is controlled by breakdowncrystallization reactions. The obtained temperatures are not "blocking" temperatures, but mostly reflect discrete metamorphic episodes during the overall cooling history.