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NOVAS EVIDÊNCIAS DE TECTONISMO CENOZÓICO NA REGIÃO SUDESTE DO BRASIL: O GRÁBEN DE BARRA DE,SÃO JOÃO NA PLATAFORMA DE CABO FRIO, RJ

1990; Sociedade Brasileira de Geologia; Volume: 20; Issue: 1 Linguagem: Inglês

10.25249/0375-7536.1990187196

2177-4382

Webster Ueipass Mohriak, ANA ZÉLIA NUNES DE BARROS,

Fish biology, ecology, and behavior

The western portion of the Campos Basin is limited by a hinge line that limits the deposition of pre-Aptian sediments in the offshore region.The Cabo Frio arch corresponds to a platform with smaller relative subsidence, where Tertiary sediments are deposited directly on shallow basement rocks.A conspicuous asymmetric graben occurs in the offshore region between Búzios and Macaé.This rhomb-graben measures 20 km by 40 km, with the longer axis trending NE.The central part of this graben is located eastwards of Barra de São João, where the water depth ranges from 20 to SO m.The southern border of the graben is controlled by an antithetic normal fault which effects the basement by at least 500 m.The sedimentary sequence, which probably reaches the Eocene, shows a substantial tilting that decreases towards the top, indicating diastrophic tectonic activity during the Tertiary.The geological and geophysical characteristics of the Barra de São João graben supports a genetic affiliation with the onshore Taubaté, Resende and Volta Redonda basins, rather than with the Campos Basin.The latter basin was formed in the Neocomian by rupturing of the Pangea, while the radiometric age determination of ankaramitic lavas near Volta Redonda suggests that the onshore basins were formed during the Eocene or Early Oligocene.A better understanding of the crustal geometry and the postulation o'f geodynamic medels for these sedimentary basins will result from the integration of the onshore geology with the subsurface data presented in this paper.