Литосфера (Dec 2015)
Metasomatites of medium and mafic composition from Nyaschevo massif (Ilmeny Mauntains, South Urals)
Abstract
The results of the study of mediosiliceous and mafic metasomatites located in ultramafic and mafic rocks Nyaschevo massif presents in the paper. The texthural and structural features of these rocks allow to attribute them to tectonites - protomylonites and mylonites. Mineralogical and geochemical characteristics of the rocks indicate to polycyclic process of metamorphism accompanied by metasomatic transformation. The metasomatites of medium composition have been characterized the primary of magmatic origins followed by metamorphic and regional deformation processes associated with metasomatic transformation (gedrite, cummingtonite ( T = 800-700°С, P = 2-5 kbar)).The metasomatites of mafic composition are the result of mylonitization and metasomatism under the influence of fluid induced the mobility of elements, such as Al, Ti, К, Ba and LREE. The input Mg from host serpentinites on the final stages of conversion is clear recorded in the forming of gedrite and height-magnesium enstatite. The metasomatites of mafic composition is showed the petrogeochemical connection with the rocks of syenite-carbonatite association.
