Pollen evidence for Thermophilic and Hydrophilic Terrestrial Vegetation in the Central Arctic During the Paleocene/Eocene Thermal Maximum

Rapid increases in sea-surface and continental temperature and moisture delivery to the Arctic during the global warming called the Paleocene/Eocene Thermal Maximum (PETM) have been documented by dinoflagellate cysts and organic geochemical proxies. We compare new pollen data with published dinocyst, higher-plant n-alkane isotope, TEX86 sea surface- and MBT continental-temperature records from PETM sediments recovered from Lomonosov Ridge in the central Arctic Ocean by Integrated Ocean Drilling Program Expedition 302. Substantial increases in abundance of Taxodiaceae and angiosperm pollen occur at the onset of the PETM, when Apectodinium, a subtropical dinoflagellate restricted to low latitudes before the PETM, first appears. Pollen assemblages during the PETM indicate temperate to subtropical atmospheric temperatures and greater moisture availability during this interval. A shift back to conifer-dominated assemblages later in the PETM coincides with atmospheric and sea-surface cooling, decreased abundances of Apectodinium, the termination of photic zone euxinia, and increased salinity. We will discuss new pollen evidence that is consistent with published subtropical sea-surface and atmospheric temperature reconstructions in the Arctic. These data address hypotheses on the synchroneity of ocean-land climate changes and provide new constraints on potential vital effects on higher-plant n-alkane isotope records.