Trayectoria de evolución metamórfica P-T-d del granito milonítico paleoproterozoico de Cerro Negro, megacizalla de azul, Tandilia

MARTINEZ, JUAN; FRISICALE, MARÍA CRISTINA; ANGELETTI, MELISA

San Miguel de Tucumán

Congreso; XX Congreso Geológico Argentino; 2017

ASOCIACION GEOLOGICA ARGENTINA

A granitic stripedgneiss from cerro Negro, at the western extreme of the Azul Megashear Zone,Tandilia, yields deformation microstructures generated under amphibolite faciesconditions (D1) during a metamorphic counterclockwise P-T path. Conditionsof A: 0.53 GPa - 670 ºC, B: 0.8 GPa - 650 ºC and C: 0.64 GPa - 600 ºC, weredetermined in a P-T pseudosection and through isopleths in zoned garnet withcore pyr5(gro+andr)9 spes5 alm81, intermediatezone pyr4 (gro + andr)20 spes6 alm70 andrim pyr2,5 (gro + andr)18 spes6 alm73,5 compositions.It is proposed that the metaigneous rock cooled down, from supersolidusconditions, during the tectonic overload of relatively cooler material in amedium to lower crustal zone. Microstructures of deformation generated under greenschists facies (D2) and cataclases (D3) followed oneanother during the rock exhumation.