TECTONIC REACTIVATION IN AN ANCIENT SHEAR ZONE
Reactivation, Shear Zone, Cenozoic, Faults, Geomorphic
Old shear zones in an intra-plate environment can be reactivated by
more recent tectonic events. In the region of São Tomé das Letras and its surroundings, the
reactivation of the Caxambu Shear Zone, in the Cenozoic, has a major influence on the
on the relief modeling and drainage network. The combination of modern techniques,
including the application of geomorphic indices, qualitative and quantitative geomorphological
and quantitative geomorphological analysis, combined with structural mapping (faults, fractures and striations) and analysis of
analysis, enabled a detailed investigation of the structures affecting the region.
With the results obtained, the dominant structural trends were defined, with a main direction of
E-W and NE-SW, and the occurrence of six tectonic events: NE-SW thrust,
NE-SW sinistral transpression, E-W sinistral transpression, NW-SE distension, NE-SW destral
NE-SW and NE-SW sinistral transpression. Together, these data suggest that the
ancient structures have been reactivated and are responsible not only for the current conformation of the
relief, but also for deviations in drainage, anomalies, the formation of rapids, valleys
and waterfalls.