Abstract

Multibeam echo sounder (MBES) bathymetry and backscatter data from the 2013 R/V Falkor survey are used to define the Cretaceous–Paleogene (K-Pg) boundary deposit outcropping on the Campeche Escarpment and to characterize large-scale erosional processes on the Campeche shelf. We delineate the escarpment into four geomorphic provinces based on submarine canyon density and morphology, as well as pronounced geomorphological differences formed in response to erosional processes along strike of the Campeche Escarpment. Large-scale, retrogressive-appearing mass wasting has left high-angle scarps where large slabs of sediment have eroded the escarpment edge, giving the slope a terraced appearance. This erosion reveals higher backscatter intensity material overlain with remnants of lower backscatter intensity sediments within the slide scar. We infer this high-intensity backscatter material to be predominantly carbonate layers on which erosion occurred. The most prominent high-intensity backscatter layer is interpreted to identify the K-Pg boundary deposit (KPBD) that was reported previously based on a steep bathymetric change and constrained by cores from Deep Sea Drilling Project (DSDP) Sites 86 and 94. Given its proximity to the impact crater, the KPBD is likely to be composed of a massive impact breccia. Upslope, high-intensity backscatter layers are inferred to represent postimpact carbonates that progressively infilled the basin flank after the Chicxulub bolide impact. Lower intensity backscatter material is inferred to be fine-grained Cenozoic sediment drape. The stark contrast observed in MBES backscatter data between high-intensity carbonate material and lower-intensity sediments refines and constrains the location of the K-Pg boundary deposit exposed along the Campeche escarpment and provides new insights into the carbonate platform's postbolide impact evolution as observed in the erosional styles of the Campeche escarpment.

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