PALEOAMBIENTES E ICNOFÁCEIS DA SEQÜÊNCIA CARBONÁTICA DA BACIA DA PARAÍBA (CRETÁCEO-PALEOGENO), NORDESTE DO BRASIL

Abstract

This work deals an investigation of the stratigraphic, sedimentological and paleontological aspects, mainly ichnologic, in outcrops of carbonate deposits of the Gramame and Maria Farinha formations in the Paraiba Basin, northeast Brazil. The objective of the investigation was to obtain detailed information on the depositional environments of these units. The Gramame Formation was deposited in a regime of highstandstand system tract, belowstand the base level of fair weather waves where prevailed conditions of soft bottom and lowstand energy, but often reached by storm events, correlated to the Cruziana ichnofacies. The Maria Farinha Formation was deposited during a regressive event, with the increase of energy and siliciclastic input, important lateral facies variation and Cruziana-Skolithos ichnofacies . The eocenic carbonate rocks, that occur in the south coast of Paraiba state, present s expressive difference from the deposits of the typical Maria Farinha Formation, and it could represent another unit. These reefal carbonates was deposited in reef-lagoon s complexes and arc se pa rated from the Maria Farinha Formation by an unconformity and, probably indicate the establishment of a lowstand system tract . The ichnofacies interpreted for them was Trypanites?. The data integration suggests a paleobathymetry of middle to inner platform (150-80m), for the Gramame Formation, and inner platform to infralitoral (60-20m), including proximity of estuaries, for the Maria Farinha Formation.