STRONTIUM ISOTOPE PROFILES ACROSS K T BOUNDARY SEQUENCES IN DENMARK AND ANTARCTICA/

Strontium isotope profiles, derived from minimally altered samples, ac ross marine K/T boundary sequences exposed at Kjolby Gaard and Nye Klo v, Denmark, and on Seymour Island, Antarctica, show neither the bounda ry excursions, nor the boundary spikes, in Sr-87/Sr-86 that have been reported for K/T boundary sequences from elsewhere. Nor do our data co nform to modelled predictions of the Sr isotopic response of the ocean s to a positive spike in Sr-87/Sr-86 at the terminal Cretaceous. Bound ary values for Sr-87/Sr-86 (With 95% confidence intervals) are 0.70782 8 +/- 3 in Denmark and 0.707832 +/- 7 in Antarctica. Our data suggest that Sr-87/Sr-86 stopped increasing and started decreasing at least 90 ka before the K/T boundary. (C) 1998 Elsevier Science B.V. All rights reserved.