Garnet-pyroxene and lawsonite-bearing rocks of the Maksyutov Complex (Southern Urals)

Abstract

The new petrological and geochrological data are used to constrain the nature of garnet-clinopyroxene and lawsonite-bearing rocks, which contain a rare variety of Fe-Ca-rich garnets. These rocks associated with antigorite serpentinites have no equivalents in the other units of the Maksyutov eclogite-glaucophane schist complex and, thus, can be regarded as a separate “mafic-ultramafic” unit. Based on their mineral and chemical composition, the garnet-clinopyroxene and lawsonite-bearing rocks can be interpreted as HP associations formed within a deep continental rifting setting. They experienced a series of metasomatic alterations during decompression exhumation and were accreted to the Maksyutov Complex as a result of the arc-continent collision. The U–Pb zircon data indicate that a Late Riphean–Lower Paleozoic age (824 and 440–470 Ma) was a crystallization age of garnet-clinopyroxene rocks and Ar–Ar white mica age (341 ± 2 Ma) represents the timing of the final accretion of all structural unit to the Maksyutov Complex.