Mecanismos de deformación en la transición milonitas/striped gneiss y milonitas/ ultramilonitas en las sierras de Azul, cratón del Río de la Plata, Buenos Aires

摘要: 2 INGEOSUR-CONICET 3 INGEOSUR-CIC ABSTRACT: Deformation mechanisms in the mylonite/striped gneiss and mylonite/ultramylonite transition Sierras de Azul, Rio la Plata cra- ton, Buenos Aires. At western sector of Azul Megashear, mylonitic rocks with variable deformation that includes pro- tomylonites, mylonites, ribbon striped ultramylonites were identified. A detailed examination defor- mation acting on main minerals like feldspar, quartz, amphibole pyroxene was done. The analysis allowed to establish metamorphic degree reached this shear zone. Thus, two areas different conditions recognized. One them, involve outcrops Sector Norte, Cerro Negro Manantiales Pereda, a produced under amphibolite granulite facies (temperatures higher than 600o); other less intense condi- tions greenschists facies, involving La Manuela Chiquita. Furthermore, meso microscopic ki- nematic indicators such as S-C structures, fragmented rigid grains, rotated porphyroclasts mineral-fish structures analyzed order sense movement rock masses region compare it results else- where Megashear.