Evolution of Antarctic waters during the Maestrichtian: foraminifer oxygen and carbon isotope ratios, Leg 113

Abstract

Oxygen and carbon isotopic ratios were measured from Maestrichtian benthic and planktonic foraminifer species and bulk carbonate samples from ODP Sites 689 and 690, drilled on the Maud Rise during Leg 113. Foraminifer δ18O values at both sites document a cooling trend during early Maestrichtian time, a rapid drop in water temperatures at the time of the first appearance of Abathomphalus mayaroensis in the high southern latitude regions (about 69.9 Ma) and lower water temperatures during late Maestrichtian time. δ13C values record a depletion in 13C in the latest early Maestrichtian time beginning at about 72.2 Ma, just prior to the sharp late Maestrichtian increase in δ18O values. Benthic and planktonic foraminfer δ13C values fluctuate sympathetically and are higher in upper Maestrichtian sediments than in the lower Maestrichtian sequence. -from Authors