Stable carbon and oxygen isotope ratios across the Cretaceous/Tertiary boundray on the Walvish Ridge

The stratigraphic range of the samples is from the Arkhangelskiella cymbiformis Zone in the Maastrichtian to the Heliolithus kleinpelli Zone in the Danian.

Nannofossil diversity was high (Shannon-Weaver diversity index, 'H= 2.5-3) in the late Cretaceous, but decreased sharply (H c. 1 ) across the K/T boundary. The delta13C values also decrease across the K/T boundary at the four sites, suggesting a reduction in surface productivity in the South Atlantic concomitant with the reduction in diversity. During the Danian, nannofossil diversity and delta13C show some recovery approximately 500-700 k.y. after the boundary event.