ASSOCIAÇÃO TECTONO-LITOLÓGICA DA PALEOZONA DE SUTURA ALTEROSA- SUDESTE DO BRASIL.

Abstract

Along the Alterosa Paleosuture Zone occurs a metavolcanosedimentary sequence associated to orthogneisses and syn- to tardi- tectonic granites. Intercalations of mafic and ultramafic rocks with lenses of iron formations are interpreted as ophiolites. The rocks units that crop out in the Northern and the South portions of the Alterosa suture zone were juxtaposed during Neoproterozoic continental collision when the Archaean terrenes and Neoproterozoic metasedimentary rocks were overthrusted by Guaxupé Complex resulting in present geological scenario.In the Northern of Alterosa suture an Archaean gneissicgranitic- greenstone terrene crops out, locally crosscut by Paleoproterozoic intrusive basic rocks or covered by Neoproterozoic platform metasedimentary rocks. This association was inhomogeneous affected by the Neoproterozoic tectono-metamorphic processes in the greenschist facies environment. In the south of Alterosa suture the lower crust of the obducted plate crops out, constituted by basic to acid granulites, syntectonic granitoid rocks and metasedimentary intercalations. In side this domain, the metamorphic peak reached temperatures over 950ºC and pressures of the order of 15 kbar, as shown by uplifted portions during the movement to the East. Along the Alterosa suture zone the metamorphism was stronger in the Southern portion, where pressures higher than 15 kbar and temperatures of the order of 800ºC were reached.