ALBERT

Description: The response of the Earth System to greenhouse-gas driven warming is of critical importance for the future trajectory of our planetary environment. Hypethermal events – past climate transients with significant global-scale warming – can provide insights into the nature and magnitude of these responses. The largest hyperthermal of the Cenozoic was the Palaeocene-Eocene Thermal Maximum (PETM ~ 56 Ma). Here we present a new high-resolution cyclostratigraphy for the classic PETM section at Zumaia, Spain. With this new age model we are able to demonstrate that detrital sediment accumulation rates within this continental margin section increased more than four-fold during the PETM, representing a radical change in regional hydrology that drove dramatic increases in terrestrial to marine sediment flux. During the body of the PETM, orbital-scale variations in bulk sediment Si/Fe ratios are evidence for the continued orbital pacing of sediment erosion and transport processes, most likely linked to precession controls on sub-tropical hydroclimates. Most remarkable is that detrital accumulation rates remain high throughout the body of the PETM, and even reach peak values during the recovery phase of the characteristic PETM carbon isotope excursion (CIE). Using a series of Earth System Model inversions, we demonstrate that the silicate weathering feedback alone is insufficient to recover the PETM CIE, and that active organic carbon burial is required to match the observed dynamics of the CIE. Further, that the period of maximum organic carbon sequestration coincides with the peak in detrital accumulation rates observed at Zumaia. Based on these results, we hypothesize that precession controls on tropical and sub-tropical hydroclimates, and the sediment dynamics associated with this variation, play a significant role in the timing of the rapid climate and CIE recovery from peak-PETM conditions.