Roveacrinids in mid-Cretaceous biostratigraphy of the Sergipe Basin, northeastern Brazil

As part of a study of the Cenomanian–Coniacian sedimentary succession in the Sergipe Basin in northeastern Brazil, microfacies analyses were tested for possible chronostratigraphic application. The common and widespread remains of roveacrinid echinoderms proved useful for intrabasinal biochronostratigraphy. Local dolomitization in the basin, which destroyed most other fossil remains, left the magnesian-calcitic roveacrinid skeletons largely unaffected. Thus, where diagnostic fossils are scarce or lacking, roveacrinids may provide an ancillary means of chronostratigraphic correlation. The forms recorded from Sergipe are described, and a stratigraphic range chart is presented for intrabasinal application, with the possibility of regional or even global correlation either qualitatively (presence/absence patterns) or quantitatively (eco-event patterns). Several roveacrinid abundance horizons have been reported worldwide in relation to sea level changes and associated hypoxic events, during which roveacrinids developed abundant opportunistic populations. The present study of the Sergipe Basin provides a basis for comparisons and correlations of roveacrinid occurrences in the mid-Cretaceous succession of the South Atlantic continental margin basins and ODP/DSDP drill cores.