Reconstructing Changes in Deep Ocean Temperature and Global Carbon Cycle during the Early Eocene Warming Trend: High-Resolution Benthic Stable Isotope Records from the SE Atlantic.

From the late Paleocene to the early Eocene, Earth’s surface temperatures generally rose, resulting in an increase of at least 5°C in the deep ocean and culminating in the Early Eocene Climatic Optimum (EECO). This long-term warming was punctuated by a series of short-lived global warming events known as “hyperthermals”, of which the Paleocene-Eocene Thermal Maximum (PETM) represents the most extreme example. At least two other short-term episodes have been identified as hyperthermals: the ETM2 (or Elmo event) at about 53.7 Myr and the ETM3 (or X-event) at about 52.5 Myr. These transient events are marked by prominent carbon isotope excursions (CIEs), recorded in marine and continental sedimentary sequences and driven by fast and massive injections of ¹³C-depleted carbon into the ocean-atmosphere system. Recently, evidence has indicated the presence of a regular series of hyperthermal events following the peak in temperatures of the EECO. However, continuous records are needed to investigate short- and long- term changes in the climate system throughout the Early Eocene warming trend. Here, we present new high-resolution benthic stable isotope records of the Early Eocene from ODP Site 1263, (Walvis Ridge, SE Atlantic). The carbon and oxygen records document changes in deep-sea temperature and global carbon cycle encompassing the Early Eocene hyperthermal events and the EECO interval. The transition phase to the post-EECO events is distinct by the decoupling of carbon and oxygen isotopes on the long-term scale. Spectral and wavelet analyses suggest the influence of orbital forcing, specifically long and short eccentricity cycles.