Geological map of the cenozoic of Volta Redonda basin region (Rio de Janeiro State, central segment of the Continental Rift of Southeastern Brazil): Identification of new grabens and discontinuous occurrences, and characterization of tectonosedimentary stages

Abstract

This work aims to present new results of geological mapping and tectonosedimentary analysis of the cenozoic of Volta Redonda basin region, inserted in the central segment of the Continental Rift of Southeast Brazil (CRSB). Were recognized three paleogenic depocenters (grabens of Colônia Santo Antônio, Dorândia, Casa de Pedra - most importantly, for its volcanic and sedimentary record) and discontinuous paleogenics deposits (areas of Belmonte, Jardim Amalia, Cafundó, Vargem Alegre), and two expressives quaternary grabens (grabens of the Rio Bananal and the Usinal), distributed in the NE-SW direction. The paleogenic filling was related to three tectonic stages: Pre-Rift phase, linked to the deposition of the Ribeirão Quatis Formation (fluvial); Rift phase I (main), related to Resende Formation, characterized by a fluvial and alluvial fan systems associated with major fault edges, and basanitic volcanism (Casa de Pedra Basanite); Rift phase II (final) relating to Pinheiral Formation fluvial deposits, responsible for clogging of paleogenics depocenters. Significant accumulations of recent alluvial deposits are linked to the fulfillment of the Quaternary grabens. The current configuration of the Volta Redonda basin region is the results of a generation of several brittle structures associated to paleogenic opening and neotectonic deformation. Thus, this segment of the CRSB is represented by a mosaic of paleogenic dpocenters and discontinuous occurrences significantly compartmentalized by recent deformation, and quaternary depocenters, mainly linked to the Holocene extension event. The identification and characterization of these feautures, brings a new arrangement of cenozoic record in the region of the Volta Redonda basin, measuring around 40 km in the NE-SW and 10 km in the NW-SE direction.