title: 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 δ(18)O cycles that imply a climatic origin. Seasonal insolation is the only regular climate cycle that can plausibly account for δ(18)O amplitudes and layer counts. High-resolution stable isotope records show 3.5‰ δ(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 δ(13)C gradient developed on the shelf with the largest excursions in shallowest waters, indicating atmospheric δ(13)C decreased by ~20‰. Our observations and revised release rate are consistent with an atmospheric perturbation of 3,000-gigatons of carbon (GtC).
authors.affiliation: Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854.
authors.forename: James D
authors.initials: JD
authors.lastname: Wright
authors.forename: Morgan F
authors.initials: MF
authors.lastname: Schaller
mesh_terms: D001272:Atmosphere / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis*; D057231:Climate Change; D019015:Geologic Sediments / Q000032:analysis*; D005844:Geology / Q000379:methods*; D049690:History, Ancient; D009792:Oceans and Seas
chemical_list: D002247:Carbon Isotopes
keywords: carbon cycle; climate change
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