An integrated Cretaceous microfossil biostratigraphy

An integrated calcareous nannoplankton, calpionellid, and planktonic foraminifer biostratigraphy was constructed for the Cretaceous Period. This biostratigraphy, which consists of 73 informal zones, is based upon a literature survey of numerous DSDP/ODP and land sections as well as investigations of several of these sequences. Although the sections included are from low, mid, and high latitudes, from all of the major ocean basins and from epicontinental seaways, the integrated scheme is most applicable in mid- and low-latitude sequences. Current nannofossil, calpionellid, and planktonic foraminiferal zonations offer limited resolution (2-6 my/zone) in the Cretaceous Period. The integrated zonation scheme proposed significantly increases potential biostratigraphic resolution to between 0.5 and 1.5 my/zone because these fossil groups are often worked on collectively, and because the correlation between the groups is reasonably well known in most intervals. -Authors