Abstract
Abstract The mid-Atlantic coastal plain (eastern United States) preserves high-resolution records of the Paleocene-Eocene Thermal Maximum (PETM) and attendant carbon isotope excursion (CIE), though preservation is highly variable from site to site. Here, we use a dip transect of expanded (as much as 15 m thick) PETM sections from the New Jersey coastal plain to build a cross-shelf PETM depositional model that explains the variability of these records. We invoke enhanced delivery of fine-grained sediments, due to the rapid environmental changes associated with this hyperthermal event, to explain relatively thick PETM deposits. We utilize δ13Cbulk, percent CaCO3, and percent coarse fraction (>63 μm) data, supported by biostratigraphic records, to correlate sites along a paleoslope dip transect. Updip cores from Medford, New Jersey, preserve expanded sections of the initiation of the PETM and the earliest portion of the CIE. Medial sites (Wilson Lake, Millville) preserve an expanded CIE body, and downdip Bass River records the CIE recovery. We interpret this pattern to reflect the progradation of clinoform foresets across the paleoshelf via fluid mud, similar to modern high-sediment-supply rivers and adjacent muddy shelves (e.g., the Amazon, Mahakam [Indonesia], and Ayeyarwady [Myanmar] Rivers). Our subaqueous-clinoform delta model explains the pattern of the CIE records and provides a framework for future PETM studies in the region.
Highlights
The Paleocene-Eocene Thermal Maximum (PETM; 56 Ma) and attendant carbon isotope excursion (CIE) represent the largest warming event and carbon cycle perturbation of the Cenozoic
At site MAP 3, the transitional unit captures the CIE onset and part of the subsequent CIE decrease. This CIE decrease is extremely sharp in open ocean sites, which, in conjunction with the biostratigraphic correlations, suggests far higher rates of sedimentation on the New Jersey coastal plains (NJCP): 2.7 m of sediment preserves the CIE onset and initial CIE decrease at hole MAP 3B, versus
Geochemical, sedimentological, and biostratigraphic records demonstrate that deposition on the New Jersey paleoshelf during the PETM consisted of prograding depocenters
Summary
The Paleocene-Eocene Thermal Maximum (PETM; 56 Ma) and attendant carbon isotope excursion (CIE) represent the largest warming event and carbon cycle perturbation of the Cenozoic. Global temperatures rose by 4–8 °C (e.g., Kennett and Stott, 1991; Zachos et al, 2003) while δ13C values decreased by 2‰–4‰ in marine sections (foraminiferal and organic records) and by as much as 7.6‰ in the terrestrial realm (plant lipids) (see McInerney and Wing [2011] for a full review of CIE proxies). Understanding the trigger, rate, and timing of this light-carbon injection is hindered, in part, because most marine CIE-PETM sections are thin (
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