Evidence for a rapid release of carbon at the Paleocene-Eocene thermal maximum.

ABSTRACT: The Paleocene/Eocene thermal maximum (PETM) and associated carbon isotope excursion (CIE) are often touted as the best geologic analog for the current anthropogenic rise in pCO2. However, a causal mechanism for the PETM CIE remains unidentified because of large uncertainties in the duration of the CIE's onset. Here, we report on a sequence of rhythmic sedimentary couplets comprising the Paleocene/Eocene Marlboro Clay (Salisbury Embayment). These couplets have corresponding ?(18)O cycles that imply a climatic origin. Seasonal insolation is the only regular climate cycle that can plausibly account for ?(18)O amplitudes and layer counts. High-resolution stable isotope records show 3.5‰ ?(13)C decrease over 13 couplets defining the CIE onset, which requires a large, instantaneous release of (13)C-depleted carbon. During the CIE, a clear ?(13)C gradient developed on the shelf with the largest excursions in shallowest waters, indicating atmospheric ?(13)C decreased by ~20‰. Our observations and revised release rate are consistent with an atmospheric perturbation of 3,000-gigatons of carbon (GtC).

SUBMITTER: Wright JD 

PROVIDER: S-EPMC3791743 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature