Thermobarometric and Petrological Study of Mafic Xenolithes in Plagiogranites of the River Lotta Area of the Central Zone of the Lapland Granulite Belt

Thermobarometric data, fluid inclusions data and carbon isotope data confirm the conclusion that leucocratic garnet - bearing plagiogranites of the Lapland Granulite Belt (LGB) are associated with the anatexis of country khondalites during peak of metamorphi sm. The formation of these magmas occurred at depths of 25 - 30 km. During ascent, granitic magmas trapped mafic (two pyroxene - plagioclase) xenoliths at pressures 6.0 - 6.4 kbar. The interaction of predominantly aqueous - salt fluids issued by the magmas with th e xenoliths during cooling at depths less than 20 km (5.0 - 5.5 kbar) led to their widespread amphibolization at temperatures of 740 - 780°C.