Composición de biotitas y anfíboles del Batolito de Las Chacras - Potrerillos: Implicancias geoquímicas para el magmatismo Devónico Medio de la Sierra de San Luis

the las chacras - potrerillos batholith is the largest devonian igneous unit that crops out in sierra de san luis. according to its silica content it is divided into two suites: monzonitic ( 65% sio2). new mineral chemical data obtained by electronic microprobe on biotites and amphiboles of both suites are presented. the analysis of biotite composition indicates that mg/(mg + fe) is higher for the monzonitic suites and the calc-alkaline, metaluminous to peraluminous magmatic signature. emplacement pressure calculated from the amphibole data are bracketed between 3,3 - 4,6 kbar (monzonitic suite) and 4,2 - 4,7 kbar (granitic suite).