Garnet peridotite from the Pohorje Mountains
The Pohorje Mountains form a polymetamorphic horst, situated along the Periadriatic lineament. North of Slovenska Bistrica a peridotite body measuring 5 by 1 km extends in the general E-W tectonic trend of the area. It consists mainly of dunite and harzburgite, with some small garnet-bearing peridotite lenses included too. Veinforming clinopyroxene crystals up to 6 cm in size, though uncommon, show complex unmixing textures with olivine and garnet. The peridotite body is abundantly interlayered with streaks and lenses of kyanite eclogite. The relation of garnet peridotite to other mentioned rocks points out their common crystallisation under high granulite and/or eclogite facies conditions. The rocks were tectonically emplaced into their present crustal environment and subjected to retrogressive metamorphism of different degrees. The representative ultramafic rock types are petrographically described.