NANNOFOSSIL DIVERSITY AND EQUITABILITY AND FINE-FRACTION DELTA C-13 ACROSS THE CRETACEOUS TERTIARY BOUNDARY AT WALVIS RIDGE LEG-74, SOUTH-ATLANTIC Academic Article uri icon

abstract

  • The isotopic composition and diversity of nannofossils were studied in cores from the Deep Sea Drilling Project (DSDP) Sites 525A, 527, 528, and 529 from the Walvis Ridge, South Atlantic to better understand the changes which occurred across the Cretaceous/Tertiary boundary (K/T boundary). 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 (H1) across the K/T boundary. The 13C 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 13C show some recovery approximately 500-700 k.y. after the boundary event. However, not until 2.5 Ma after the boundary event did diversity become constant. Diversity values similar to those for the late Cretaceous were not attained again in the early Paleocene interval studied. Carbon isotopic compositions similar to those from the Cretaceous were not attained until 4.5 Ma after the K/T event. 1992.

published proceedings

  • MARINE MICROPALEONTOLOGY

author list (cited authors)

  • ALCALAHERRERA, J. A., GROSSMAN, E. L., & GARTNER, S.

citation count

  • 21

complete list of authors

  • ALCALAHERRERA, JA||GROSSMAN, EL||GARTNER, S

publication date

  • October 1992