| Popis: |
Due to the complex geodynamic framework and the excellent state of preservation of the stratigraphic relationships towards the host metamorphic and sedimentary rocks, the Permo-Triassic magmatic sequences of the Southern Alps (Italy) are intensely studied. Throughout the Southalpine domain, the main peaks of the volcano-plutonic activity are both pre- and post-dated by the emplacement of small volume of magmas with variable chemical affinity. These magmas, preserved as dykes and veins intruded into the plutonic bodies and/or the overlying volcanites, are powerful tools for tracing the evolution of the magma source and reconstructing the temporal evolution of the magmatic episode. Here, we present a detailed geochemical and geochronological study of phonolitic dykes (SiO2 from 56.8 to 57.8 wt.%; Na2O + K2O from 11.1 to 15.3 wt.%) cropping out near Predazzo (Southern Alps; Italy) and intruded into the basaltic to trachyandesitic Middle Triassic lavas. The phonolites are mostly aphyric with a porphyricity index |
