Palynological Response to Middle Eocene Climate Variability in the North Atlantic Ocean: IODP Expedition 342, Newfoundland Ridge, Offshore Canada

Proxy records from Eocene hyperthermals provide evidence for rates and magnitudes of environmental changes associated with these events, as well as their impacts on terrestrial and marine ecosystems. The Middle Eocene Climatic Optimum (MECO) occurred ~40 Million years ago (Ma) and lasted ~500,000 years, and previous research has documented changes in marine and terrestrial biotas during and after this event. Cores collected in sediment drifts on Newfoundland Ridge off the coast of eastern Canada during IODP Expedition 342 recovered expanded sections of the middle Eocene, with sedimentation rates of 1-2 cm/kyr. We present results from pollen, palynofacies, and dinocyst analyses from Sites 1408 (41.438'N, 49.786'W, 3022 mwd), 1409 (41.296'N, 49.233'W, 3501 mwd), and 1410 (41.328'N, 49.170'W, 3387 mwd), spanning an interval that includes the MECO. Palynological assemblages are well preserved throughout the middle Eocene at Sites 1408 and 1410, whereas carbonate-rich samples from Site 1409 were completely barren of palynomorphs. Substantial variability in dinocyst species composition and diversity, pollen assemblages, and organic palynofacies were observed within the MECO event. Fluctuations in concentrations of opaque organic matter, insect fragments, and pollen and spores from terrestrial vegetation reflect changes in terrigenous influx, intensity of the hydrologic cycle, and source vegetation. Dinocyst assemblage shifts are correlated with changes in productivity, nutrient supply, and salinity. Integration of palynological data with other proxies will provide further insights into correlations between increased terrigenous input and eutrophication, leads and lags between terrestrial and marine responses to climate fluctuations, and environmental stability during the Middle Eocene.