87Sr/86Sr results for the Maastrichtian samples from ODP Leg 171

The slumps and hiatus occur within a sequence dominated by pelagic chalk. The 87Sr/86Sr measurements show a general increase through the Maastrichtian at each site, but suggest chronostratigraphic gaps on the order of 10 Myr across the slumps.

Some of the slumps have burrowed upper surfaces and are composed of material that is older and coarser grained than the bounding chalks. Pelagic deposition punctuated by gravity flows easily explains the Maastrichtian record on Blake Nose, whereas an impact-based explanation for slumping is difficult to reconcile with sedimentological and geochemical observations.