Abstract

Seismic reflection data combined with results from ocean drilling document regional-scale slumping associated with the Cretaceous-Tertiary (K-T) impact event. The K-T boundary is biostratigraphically complete at three Ocean Drilling Program sites (1049, 1050, and 1052) located on Blake Nose (30°N, 75°W) off eastern Florida in water depths of 1300–2600 m. Maastrichtian chalk is folded and fractured below the K-T boundary at all three sites, whereas lowermost Paleocene clays and chalks are undeformed. Deformation is pervasive in Maastrichtian at the deepest water site (Site 1049), whereas at the shallower water sites (Sites 1050 and 1052) thick intervals of structurally intact Maastrichtian chalk are separated by thinner intervals of highly deformed sediments. Correlation of core to seismic reflection data indicates that the K-T boundary immediately overlies seismic facies characteristic of mass wasting that extend across most of the ∼55 km distance of the depth transect. Maastrichtian sediments appear to have moved as large slump blocks on the upper part of Blake Nose but deformed more uniformly in the deeper water parts of the transect. We suggest that mass wasting occurred on the Blake Nose >1600 km from the Chicxulub crater in response to the cataclysmic seismicity generated by the impact.

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