ENCLAVES IN THE S-TYPE GRANITES OF THE KOSSEINE MASSIF (FICHTELGEBIRGE, GERMANY) - IMPLICATIONS FOR THE ORIGIN OF GRANITES

The Hercynian peraluminous granites of the Kosseine massif differ in c omposition and content of enclaves from the other granites of the Fich telgebirge. They are garnet-, cordierite- and andalusite-bearing S-typ e granites containing at least five different types of enclaves. Based on petrography and geochemical data, including radiogenic isotopes, t he following is concluded: The amphibolite enclave (AE) and most of th e aluminium silicate-bearing surmicaceous enclaves (SEA) are country-r ock xenoliths picked up by the granite at or close to the emplacement level. The orthopyroxene-bearing surmicaceous enclave (SEO) probably r epresents a restite from the source level of the granite. The gneiss e nclaves (GE) could be fragments of Saxothuringian paragneisses taken u p by the granite near the source level. The pale microgranular enclave s with igneous texture (PMEI) could be fragments of a yet-unknown gran itic material or unmelted igneous material of an inhomogeneous source. The biotite-rich microgranular enclaves with igneous texture (BMEI) a nd the microgranular enclaves with polygonal texture (MEP) represent m aterial which derives from the source region of the granite. The Kosse ine granites represent an independent intrusion among the Fichtelgebir ge granites formed by a combination of incomplete restite unmixing, as similation and probably fractional crystallization in the course of ma gma formation, ascent and emplacement.