%0 Journal Article
%T Geometria e evolu£¿£¿o do feixe de zonas de cisalhamento Manhua£¿u - Santa Margarida, Or¨®geno Ara£¿ua¨ª, MG
%A Silva
%A Cl¨¢udio Maur¨ªcio Teixeira da
%A Alkmim
%A Fernando Flecha
%A Pedrosa-Soares
%A Ant£¿nio Carlos
%J Rem: Revista Escola de Minas
%D 2009
%I Escola de Minas
%R 10.1590/S0370-44672009000100005
%X the n-s trending manhua£¿u-santa margarida shear zone system extends for ca. 300 km in eastern minas gerais. as one of the main structures of the crystalline core of the neoproterozoic ara£¿ua¨ª orogen, the manhua£¿u-santa margarida system is made up of a series of ductile shear zones, which show a sigmoidal trace in map view. the northern segment of the system mainly consists of west-verging thrusts and subordinate dextral strike-slip shear zones. the central and southern segments are dominated by dextral strike-slip shear zones. the development of the manhua£¿u-santa margarida system occurs in four distinct neoproterozoic deformation phases. during the first phase, the system nucleated as a series of thrust shear zones, which remain preserved in the northern segment. during the second phase, the thrust zones experienced a clockwise rotation coupled with an intensive strike-slip reactivation, becoming vertical and ne-striking in the southern portion of the orogen. the third deformation phase generated normal-sense shear zones, observed only in the northern segment of the system. brittle deformation along wnw-striking fault zones and jointing are the manifestations of the fourth and youngest deformation phase. the southern segment of the manhua£¿u-santa margarida system, dominated by dextral strike-slip zones, rotates progressively to a ne orientation and merges with the structures of the northwestern segment of the ribeira belt. therefore, the structures of the southern termination of the manhua£¿u-santa margarida system are of the same age or slight older than the dextral strike-slip shear zones that characterize the tectonic grain of the northwestern portion of the ribeira belt.
%K strike-slip shear zones
%K ara£¿ua¨ª orogen
%K ribeira belt
%K brasiliano.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0370-44672009000100005&lng=en&nrm=iso&tlng=en