ИСТИНА

New analytical data on the composition and zonality of the main rock-forming minerals from the eclogites of HP-UHP Maksyutov complex (the Southern Urals) make it possible to critically evaluate the physicochemical conditions of its formation and evolution. Maximum temperatures and pressures for Grt + Cpx ± Pl + Qz of equilibrium (T ~ 805-910 ° C, P ~ 2.5-3.5 GPa), recorded in the compositions of coexisting phases, indicate possible HP-UHP conditions for the formation of the complex in the diamond stability area. Subsequent retrograde and repeated stages of metamorphism occurred at lower parameters typical for the facies of blueschist (T ~ 450-700 ° C, P ~ 1.2-1.7 GPa) and greenschist facies (T ~ 380-470 ° C, P ~ 0.7- 1.3 GPa). There are at least four episodes of progressive and associated regressive metamorphism, with a gradual decrease in its parameters from the south (from the village of Shubino) to the north (to the village of Karayanovo). The presence of opposite zonality in the garnet grains indicates the incompleteness of the processes of establishing of the Grt-Cpx equilibrium and assumes a cyclical, intermittent nature of its crystallization.