OCCURRENCE OF PRE-BRASILIANO TECTONICS IN SERRA-NEGRA REGION, SOUTHEASTERN EDGE OF SAO-FRANCISCO CRATON (BRAZIL)

The Serra Negra Region represents a peculiar structural domain, where the effects of the Transamazonian tectonics (2.0+/-0.2 Ga), erased els ewhere in the Espinhaco Range by the Brasiliano deformation (650-550 M a), can be recognized. The most prominent structures are E-W trending thrust faults, a low-angle parallel foliation and a N-S stretching and mineral lineation. Kinematic criteria, based on microstructures and o rientation of quartz [c] axes in quartzites and gneiss, indicate consi stently a southward tectonic transport. In the domains to the south of Serra Negra, the foliation is in some places steeply dipping and show s a submeridian trend. All these structures are reworked by the Brasil iano Event, a tangential westward tectonic event responsible for a set of N-S trending regional faults and low-grade metamorphism.