Late Cretaceous and early Paleogene nutrient and paleoproductivity records from Blake Nose, western North Atlantic Ocean

Abstract

We evaluate phosphorus (P) and biogenic barium (bio‐Ba) as nutrient burial and export productivity indicators for the Late Cretaceous and early Paleogene, combining these with calcium carbonate (CaCO3), organic carbon (C), and bulk CaCO3 C isotopes (δ13C). Sample ages span 36–71 Ma (∼1 sample/0.5 m.y.) for a depth transect of sites in the western North Atlantic (Blake Nose, Ocean Drilling Program Leg 171B, Sites 1052, 1051, and 1050). We use a multitracer approach including redox conditions to investigate export productivity surrounding the global Paleocene δ13C maximum (∼57 Ma). Reducing conditions render most of the bio‐Ba record not useful for export productivity interpretations. P and organic C records indicate that regional nutrient and organic C burial were high at ∼61 and ∼69 Ma, and low during the Paleocene δ13C maximum, a time of proposed global high relative organic C burial. Observed organic C burial changes at Blake Nose cannot explain this C isotope excursion.