Neodymium isotopic reconstruction of late Paleocene–early Eocene thermohaline circulation

High-resolution, fish tooth Nd isotopic records for eight Deep Sea Drilling Project and Ocean Drilling Program sites were used to reconstruct the nature of late Paleocene–early Eocene deep-water circulation. The goal of this reconstruction was to test the hypothesis that a change in thermohaline circulation patterns caused the abrupt 4–5°C warming of deep and bottom waters at the Paleocene/Eocene boundary – the Paleocene–Eocene thermal maximum (PETM) event. The combined set of records indicates a deep-water mass common to the North and South Atlantic, Southern and Indian oceans characterized by mean ϵ Nd values of ∼−8.7, and different water masses found in the central Pacific Ocean ( ϵ Nd∼−4.3) and Caribbean Sea ( ϵ Nd∼1.2). The geographic pattern of Nd isotopic values before and during the PETM suggests a Southern Ocean deep-water formation site for deep and bottom waters in the Atlantic and Indian ocean basins. The Nd data do not contain evidence for a change in the composition of deep waters prior to the onset of the PETM. This finding is consistent with the pattern of warming established by recently published stable isotope records, suggesting that deep- and bottom-water warming during the PETM was gradual and the consequence of surface-water warming in regions of downwelling.