The Serra do Japi and adjacent countries are the result of tectonic, metamorphic and magmatic processes attributed to poliphasic events of the Trans-Amazonic and Brazilian Cycles. The Amparo Group is represented in the region by geosynclinal sequence of essentially pelitic sediments (Ermida Formation) which pass to a psamitic one in the upper part at Serra do Japi (Japi Formation). The regional metamorphism of the sequences is of amphibolite facies and penecontemporaneously processes of folding, partial migmatization and perhaps intrusion of sintectonic granites took place. The migmatites and metasediments were refolded during a second phase, and the resultant folds are those more commonly observed in the field. These phenomena are looked as due to the Trans-Amazonic Cycle. At the end of the Brazilian Cycle, post-tectonic granite bodies have intruded in the region. Some transcurrent faults which develloped after this magmatism and joints which cutt all the lithologic and structural units, represent the last structures.
