Padrão de fraturas da região da Serra dos Órgãos (RJ) e sua relação com a tectônica mesozóico-cenozóica do sudeste do Brasil

Abstract

The Serra dos Orgaos range, between Petropolis and Teresopolis cities, Rio de Janeiro State, is one of the most remarkable physiographic features of southeastern Brazilian coast. This feature, part of the Serra do Mar coastal range, with summits over 2.200 m.a.s.l, follow Precambrian basement structures constituted of metamorphic rocks intruded by several generations of granitoid rocks, included in the Oriental Terrane of the central segment of the Ribeira folded belt. After a long period of tectonic quiescence, the present-day southeastern Brazilian coastal region was subjected to an important process of tectonic reactivation, manifested since Jurassic times, which culminated with the opening of South Atlantic Ocean. Analysis of the fracture pattern of the Serra dos Orgaos range in the region of the Serra dos Orgaos National Park (Parque Nacional da Serra dos Orgaos - PARNASO) indicated the existence of five tectonic deformation phases, active from Neoproterozoic-Cambrian until the Recent times, in part correlatable with previously recognized deformations in southeastern Brazil: (1) Neoproterozoic-Cambrian left-lateral E-W-trending strike-slip; (2) and (3) Early Cretaceous and Late Cretaceous to Paleocene left-lateral E-W-trending strike-slip; (4) Eocene NW-SE-trending extension; and (5) Holocene E-W-trending compression.