Garnets from Moldanubian garnet pyroxenites and associated pyriclasites, Bohemian Massif of Lower Austria, Austria

Abstract

The garnet pyroxenites are closely related to upper mantle garnet peridotites. During the formation of the Moldanubian granulite facies complexes which have been metamorphosed under the conditions of the lower crust, lumps and fragments of the upper mantle material penetrated into the granulite facies complexes. The “primary” garnet pyroxenites have been reconstituted into granulite facies pyriclasites. Garnets from the upper mantle garnet pyroxenites are rich in pyrope and exhibit a homogeneous distribution of the elements and are therefore unzoned to a high degree. The garnets from the pyriclasites, on the other hand, are less homogeneous and frequently zoned. They are also poorer in pyrope and richer in iron, calcium and manganese. Their zonation patterns resemble to those known from granulite facies garnets.