Abstract
In the Penninic gneisses, micaschists and amphibolites of the Zillertaler Alpen (Tyrol/Austria) the garnets show two types of zoning: a) a continuous bellshaped zoning, and b) a discontinuous zoning. The garnets with a continuous zoning have cores rich in MnO and CaO and rims rich in FeO and MgO. The differences in composition between cores and rims are greater in the garnets of the Greenschist facies than in those of the Amphibolite facies. Garnets with discontinuous zoning are found in the rocks of the Greinerschiefer series and in migmatic gneisses. These garnets show an abrupt compositional change from euhedral cores very rich in MnO and poor in CaO to marginal zones rich in CaO and FeO. The discontinous zoning is due to a two stage metamorphism of possibly Cretaceous to Tertiary age. The distribution coefficients for the mineral pair garnet/biotite are about 57 for MnO and 0.3 for MgO in the Greenschist facies and 6 for MnO and 0.4 for MgO in the Amphibolite facies.
| Translated title of the contribution | Continuous and discontinuous zoning in the garnets of the Penninic rocks of the Zillertaler Alpen (Tyrol/Austria) |
|---|---|
| Original language | German |
| Pages (from-to) | 117-136 |
| Number of pages | 20 |
| Journal | Tschermaks Mineralogische und Petrographische Mitteilungen |
| Volume | 23 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jun 1976 |
| Externally published | Yes |