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 of R is due mainly to the differentiation process; the deuteric phenomenon has acted on the biotites while very little on perthites that affect the R in whole rocks.
Referenze Bibliografiche
DEER W. A., HOWIE R. A. e ZUSSMAN J. (1965) - Rock-forming minerals. Longmans, Green e Co., LTD, vol. 3.
DEL MONTE M., PAGANELLI L. e TIBURTINI R. (1965) - The feldspars from Predazzo granite, North Italy, «Miner. Petrogr. Acta», 11, 91-109.
GALLITELLI P. e SIMBOLI G. (1970) - Ricerche petrografiche e geochimiche sulle rocce di Predazzo e dei Monzoni (prov. Trento, Italia) svolte nell'Istituto di Mineralogia e Petrografia dell'Università di Bologna negli anni 1962-1970, «Miner. Petrogr. Acta», 16, 221-238.
GALLITELLI P. e SIMBOLI G. (1971) - Petrological and Geochemical Research on the Rocks of Predazzo and Monzoni (North Italy), «Verh. Geol. B-A», Heft 2, 326-343.
HALL A. (1967) - The distribution of some major and trace elements in feldspars from the Rosses and Ardara granite complexes, Donegal, Ireland, «Geochim. Cosmochim. Acta», 31, 835-847.
LUCCHINI F., MORTEN L. e ROSSI P. L. (1971) - K/Rb ratio in the intrusive rocks of the petrographic province of Predazzo (North Italy), «Miner. Petrogr. Acta», 17, 55-73.
PAGANELLI R. e TIBURTINI R. (1964) - The Predazzo Granite, North Italy, «Miner. Petrogr. Acta», 10, 57-79.
SHAW D. M. (1968) - A review of K/Rb fractionation trends by covariance analysis, «Geochim. Cosmochim. Acta», 32, 573-601.
Con il contributo del Ministero per i Beni e le Attività Culturali