Paleopalynological analysis of the albian in the Campos Basin

Abstract

The present work was aimed to identify the marine and terrestrial palynomorphs from the Campos Basin and to analyze their distribution in geological sections in order to evaluate paleoenvironmental and paleobiogeographic models. The palynological material comes from the Bonito and Pampo wells, Albian, Macaé Group. Gymnospermous pollen grains occur in considerable abundance, especially Classopolis classoides, Gnetaceapollenites spp. and Equisetosporites spp., which are typically xeromorphic. The most abundant dinoflagellates are the cosmopolitan species Spiniferites ramosus, Odontochitina operculata and Trichodinium castanea. Four typically Tethyan dinoflagellate species {Codoniella campanulata, Cyclonephelium vannophorum, Endoceratium dettmanniae and Tehamadinium mazaganense) were identified. The proportion of land-derived palynomorphs increases in the strata at the end of the Albian, concomitant with the transition from carbonates to shales and marls. Furthermore, marine palynomorphs increase in diversity from the base to the top of the studied sections, changing from a biota dominated by palynoforaminifera to one with high diversity and rich in dinoflagellates. Integration of the micropaleontological data indicates that, during the formation of the South Atlantic Ocean, the Campos Basin received water from the Tethys Ocean, which contradicts the classic model of Austral water incursion simultaneously with tectonic opening from south to north.