Warming, euxinia and sea level rise during the paleocene-eocene thermal maximum on the gulf coastal plain: Implications for ocean oxygenation and nutrient cycling
The Paleocene-Eocene Thermal Maximum (PETM, ∼ 56 Ma) was a ∼ 200 kyr episode of global warming, associated with massive injections of 13C-depleted carbon into the ocean-atmosphere system. Although climate change during the PETM is relatively well constrained, effects on marine oxygen concentrations and nutrient cycling remain largely unclear. We identify the PETM in a sediment core from the US margin of the Gulf of Mexico. Biomarker-based paleotemperature proxies (methylation of branched tetraether-cyclization of branched tetraether (MBT-CBT) and TEX86) indicate that continental air and sea surface temperatures warmed from 27-29 to ∼ 35 °C, although variations in the relative abundances of terrestrial and marine biomarkers may have influenced these estimates. Vegetation changes, as recorded from pollen assemblages, support this warming.
The PETM is bracketed by two unconformities. It overlies Paleocene silt-and mudstones and is rich in angular (thus in situ produced; autochthonous) glauconite grains, which indicate sedimentary condensation. A drop in the relative abundance of terrestrial organic matter and changes in the dinoflagellate cyst assemblages suggest that rising sea level shifted the deposition of terrigenous material landward. This is consistent with previous findings of eustatic sea level rise during the PETM. Regionally, the attribution of the glauconite-rich unit to the PETM implicates the dating of a primate fossil, argued to represent the oldest North American specimen on record.
Sluijs A.,Van Roij L.,Harrington G.J.,et al. Warming, euxinia and sea level rise during the paleocene-eocene thermal maximum on the gulf coastal plain: Implications for ocean oxygenation and nutrient cycling[J]. Climate of the Past,2014-01-01,10(4)