Ultrapotassic dykes in the Moldanubian Zone and their significance for understanding of the post-collisional mantle dynamics during Variscan orogeny in the Bohemian Massif
- Citation data:
Lithos, ISSN: 0024-4937, Vol: 272, Page: 205-221
- Publication Year:
- Repository URL:
- https://scholarworks.boisestate.edu/geo_facpubs/364; https://scholarworks.boisestate.edu/geo_facpubs/346
- Earth and Planetary Sciences; dyke swarm; ultrapotassic magmatism; Variscan Orogeny; Bohemian Massif; variscan orogeny; Earth Sciences; Geophysics and Seismology
We report mineral textures, geochemistry and age relations of two ultrapotassic dykes from a dyke swarm in the Western part of the Moldanubian Zone at contact to the Teplá-Barrandian Block. The dykes have orientation almost perpendicular to the NNE–SSW trending Central Bohemian plutonic complex and cross cut metamorphic foliation in basement gneisses and migmatites. Based on mineral compositions and geochemistry, the dykes show close relations to Mg-K syenite plutons in the Moldanubian Zone. The two dykes are vaugnerite and syenite in compositions and contain talc pseudomorphs after olivine within a fine-grained matrix that consists of K-feldspar, phlogopite with small amounts of clinopyroxene and accessory quartz, apatite, titanite and sulphides of Fe, Cu, Ni. The syenite porphyry dyke cross cuts the vaugnerite. It contains quartz phenocrysts and comparing to vaugnerite has lower modal content of talc pseudomorphs.