Arctic early Paleogene environments with special emphasis on the Paleocene-Eocene thermal maximum: A dinoflagellate and biomarker perspective

We reconstruct latest Paleocene and Early Eocene (~57 - 50 Ma) environmental trends in the Arctic Ocean, and focus on the Paleocene - Eocene thermal maximum (PETM; ~ 55 Ma), using strata recovered from the Lomonosov Ridge by Integrated Ocean Drilling Program Expedition 302. The Lomonosov Ridge was still partially subaerial during the latest Paleocene and earliest Eocene and gradually subsided during the Early Eocene. Organic dinoflagellate cyst (dinocyst) assemblages point to brackish and productive surface waters throughout the latest Paleocene and Early Eocene. Dinocyst assemblages are cosmopolitan during this time interval, suggesting warm conditions, which is corroborated by TEX86’-reconstructed temperatures of 15-18 °C. Inorganic geochemistry generally reflects reducing conditions within the sediment and euxinic conditions during the upper Lower Eocene. Spectral analysis reveals that the cyclicity, recorded in XRF scanning Fe data from close to Eocene Thermal Maximum 2 (~53 Ma; presence confirmed by dinocyst stratigraphy), is related to precession. Within the lower part of the PETM, proxy records indicate enhanced weathering, runoff, anoxia and productivity, along with sea level rise. Based on total organic carbon content and variations in sediment accumulation rates, excess organic carbon burial in the Arctic Ocean appears to have contributed significantly to the sequestration of injected carbon during the PETM.
Initial results from the WUN pACE initiative in Spitsbergen will be discussed.