Rapporto K/Rb delle pertiti e delle "biotiti" del granito di Predazzo, Val di Fiemme, Trento
In a previous work (Lucchini, Morten e Rossi, 1971) a study on K/Rb ratios for the intrusive complex of Predazzo was performed, and it was noticed that R remained mainly constant during the main differentiation process—from gabbros to syenites; only in the granitic rocks it was a strong decrease of R noticed. This decrease was ascribed both to deuteric and to differentiation phenomena. The present work, a study of R on the potassic minerals of granites (biotites and perthites), proves that the decrease...