Carbon isotope and biostratigraphic evidence for an expanded PETM section in the deep Gulf of Mexico: implications for landscape response to climate change from source to sink

We present evidence of a ca 200 m-thick Paleocene–Eocene Thermal Maximum (PETM) sedimentary section within a 543 m-thick deep-marine core in the Gulf of Mexico (GoM). The negative carbon isotope excursion (CIE) characteristic of the PETM is identified thanks to organic carbon stable isotopes and tightly linked to the Paleocene-Eocene boundary thanks to high-resolution biostratigraphic constraints provided by nannofossil and palynomorph assemblages. The unusual thickness of the CIE suggests that the PETM climate perturbation in the upstream North American catchments induced a substantial response in the downstream sectors of the Gulf Coastal Plain, and ultimately in the GoM. This relationship is illustrated in the deep-water basin by 1) the deposition of a shale interval when coarse-grained terrigenous material was trapped upstream at the onset of the PETM, and 2) considerable sediment supply in response to increased sediment transport upstream. These results are particularly relevant for paleoclimate and source-to-sink reconstructions because they link deep water sedimentation with a continental-scale paleo-drainage.