Biocronoestratigrafia de Foraminíferos em três testemunhos do Pleistoceno-Holoceno do talude continental da bacia de Campos, RJ

Abstract

Foraminiferal studies have been carried out for 222 samples from three piston cores collected on the continental slope (~1270m water depth) of Campos Basin, RJ. Samples prepared for foraminiferal investigations have been processed according to the standard methodology. A biochronostratigraphic interpretation was established with the identification of 13 planktic foram biozones: W2, W1, X3, X2, X1, Y5, Y4, Y3, Y2, Y1B, Y1A, Z2 and Z1. The W Zone occurs only in well C. The Y3 Subzone was not identified in both wells A and B, suggesting a hiatus associated to a sequence boundary unconformity. In well C, only three X subzones had been recognized, suggesting a condensed section at the W/X boundary related to a Maximum Flooding Surface (MFS). Graphic Correlation supplied absolute values of sediment accumulation rate (ranging from 7 to 30cm/Kyr) and hiatuses, from 3Kyr (well B) to 6Kyr (well A). The biochronostratigraphic and Graphic Correlation analyses indicated changes in the rate of accumulation, suggesting four different depositional settings in the slope. Analyses of the benthic and planktic fauna coupled with oxygen isotopic data show a Transgressive-Regressive-Transgressive cycle. Two fifth-order sequences and three systems tracts (TST-HST-TST) were identified. The first sequence extended for approximately 99Kyr and the second 66Kyr. Key-words: