The paleoceanographic and paleoclimatic signature of the Cretaceous/Paleogene boundary in the Antarctic: stable isotopic results from ODP Leg 113

Abstract

Stable isotopic records across the Cretaceous/Paleogene (K/P) boundary in Maud Rise Holes 689B and 690C indicate that significant climatic changes occurred during the latest Cretaceous, beginning ~500ky prior to the mass extinction event and the enrichment of iridium at the K/P boundary (66.4Ma). An oxygen isotopic decrease of ~0.7‰-~1.0‰ is recorded in the late Cretaceous planktonic and benthic foraminifers between 66.9 and 66.6Ma. The negative isotope excursion was followed by a positive excursion of similar magnitude between 66.6Ma (latest Cretaceous) and ~66.3Ma (earliest Paleocene). A major δ13C excursion occurred 200ky prior to the boundary, involving a positive shift in planktonic and benthic δ13C of ~0.5‰-0.75‰. Any model that attempts to explain the demise of the oceanic plankton at the end of the Cretaceous should consider the oceanic environmental changes that were occurring prior to the massive extinction event. -from Authors