Controversies on the placement of Cretaceous-Paleogene boundary and the K/P mass extinction of planktonic foraminifera

Abstract

Examination of recently reported K/P boundary sections indicates that the placement of the K/P boundary is based on equivocal criteria and that the boundary as placed is not synchronous. The conclusion that the K/P boundary in several U.S. Gulf Coast sections is complete and within a condensed section is simply the artifact of delineating the K/P boundary on disparate paleontologic datum planes and preservational bias of the microfossil assemblages. The upper slope and outer shelf sections at El Kef, Gredero, and Agost as well as the DSDP Site 577 section are continuous. The non-separation of Zone P0 at some deep sea sites is due to very low sedimentation rates and the short time interval of Zone P0