Feições regionais da região emersa do Alto de Cabo Frio e sua continuação para as Bacias de Campos e Santos.

Abstract

The present work presents the results of a geological and geophysical study that used several tools and methods (particularly gravimetric data, magnetic data, and field work) in the attempt to identify the megastructures in the Cabo Frio High province, and their possible continuation towards the Campos and Santos coastal basins. The same tools were also used, but with a more detailed approach in geological field work, aiming at identifying structurally and petrographically a NE-SW trending fault concordant with the main regional structural directions. This fault is here recognized and named as "Falha do Bico-Preto", and we suggested that it was tectonically active during the Late Tertiary. This fault is parallel to an importang fault known as "Falha do Pai Vitório", located near Buzios, which limits the southern border of the Barra de São João Graben, and extends towards the shallow water continental platform between Búzios and Macaé. In this study several geophysical surveys were analyzed, including magnetic, aeromagnetic, gravity, bathymetry and topography data, which were integrated with satellite images of the Cabo Frio High and along the coastal basins between the Campos and Santos basins. The field work was conducted in the area between Saquarema and Búzios, and also in the Islands of Cabo Frio platform, which were also visited during the integration of all available information. The results of the integration indicate that the NE-SW trend, which is the main direction of the regional structures observed in the onshore area, is clearly manifested in the potential field methods, and also coincide with the directions of the diabase dikes and major faults that were formed in the Early Cretaceous synrift phase that affected the marginal basins. These structures present a continuity towards the offshore area, towards the Campos and Santos basins. In the region between Ilha Grande and Cabo Frio, however, these directions are affected by the Cretaceous hinge line of the Santos Basin, with a prominent E-W direction, which limits both the synrift sequence and the transitional evaporitic sequence. Most of the megastructures could also be individualized in the geophysical interpretation, particularly the Badejo High, the Corvina Low, and the Barra de São João Graben in the Campos Basin. In the Santos Basin the potential field methods allowed the identification of the regional expression of the Cretaceous hinge line, the shelfbreak along the continental platform, and also the NW-SE trending lineaments associated with the dikes of the Ponta Grossa Arch, which also affect the onshore Paraná Basin.