Warming, euxinia and sea level rise during the Paleocene–Eocene Thermal Maximum on the Gulf Coastal Plain: implications for ocean oxygenation and nutrient cycling

• DOI: 10.5194/cp-10-1421-2014
• Publication Date: 2014-07-25T13:53:41Z
• Authors: A. Sluijs; L. van Roij; G. J. Harrington; S. Schouten; J. A. Sessa; L. J. LeVay; G.-J. Reichart; C. P. Slomp
• Keywords: Terrigenous sediment; Dinocyst; Paleoclimatology; Terrestrial plant; Paleogene

Abstract. The Paleocene–Eocene Thermal Maximum (PETM, ~ 56 Ma) was a 200 kyr episode of global warming, associated with massive injections 13C-depleted carbon into the ocean–atmosphere system. Although climate change during PETM is relatively well constrained, effects on marine oxygen concentrations and nutrient cycling remain largely unclear. We identify in sediment core from US margin Gulf Mexico. Biomarker-based paleotemperature proxies (methylation branched tetraether–cyclization tetraether (MBT–CBT) TEX86) indicate that continental air sea surface temperatures warmed 27–29 to 35 °C, although variations relative abundances terrestrial biomarkers may have influenced these estimates. Vegetation changes, as recorded pollen assemblages, support this warming. bracketed by two unconformities. It overlies Paleocene silt- mudstones rich angular (thus situ produced; autochthonous) glauconite grains, which sedimentary condensation. A drop abundance organic matter changes dinoflagellate cyst assemblages suggest rising level shifted deposition terrigenous material landward. This consistent previous findings eustatic rise PETM. Regionally, attribution glauconite-rich unit implicates dating primate fossil, argued represent oldest North American specimen record. biomarker isorenieratene within indicates euxinic photic zone conditions developed, likely seasonally, along Coastal Plain. data compilation O2 dropped all ocean basins response hydrological change, cycle feedbacks. culminated (seasonal) anoxia many margins, analogous modern trends. Seafloor deoxygenation widespread caused phosphorus regeneration suboxic anoxic sediments. argue fueled shelf eutrophication, widely microfossil studies, increasing burial margins negative feedback input If properly quantified future work, offers opportunity assess biogeochemical enhanced regeneration, timescales operates view deoxygenation.