The Cenomanian-Turonian Boundary Event (CTBE) of the New Jersey coastal plain: New insights from palynology and geochemistry

The CTBE represents one of the most pronounced oceanic anoxic events and ranks among the largest global carbon cycle perturbations in the Phanerozoic. A unique succession of strata spanning the CTBE was recovered from the Bass River borehole, New Jersey (Ocean Drilling Program Site 174AX). The CTBE consists of a ~15 m thick, dark gray laminated, fossiliferous silty clay, and was identified based on a large positive shift in δ13Corg (~2.5‰) combined with nannofossil biostratigraphy. We carried out dinoflagellate cyst (dinocyst) micropaleontology and biomarker analyses to assess climate and ecosystem changes across the event.
Dinocyst assemblages during the onset of the CTBE are dominated by open marine species (e.g. Spiniferites). Dinocyst assemblages become dominated by Paleohystrichophora and Senegalinium, suggesting intensified run off leading to a stratified water column and/or an increase in production during the event. Sea surface temperatures, reconstructed using TEX86H paleothermometry, were around 36 ºC and remained relatively constant throughout the record. The first phase of the CTBE is, however, characterized by a distinct cooling of ~3ºC. This phenomenon is recognized throughout the North Atlantic, and is therefore probably related to decreasing CO2 levels as a result of enhanced organic carbon burial.