SEISMIC STRATIGRAPHY OF EIRIK DRIFT, SOUTHERN GREENLAND MARGIN: TRACKING NORTH ATLANTIC BOTTOM WATER FLOW SINCE THE LATE MIOCENE

Eirik Drift is a detached, giant elongated drift extending roughly 400 km off the southern tip of Greenland. Sedimentation at Eirik Drift is strongly influenced by the southwest flow of North Atlantic Deep Water (NADW), a major contributor to the global thermohaline circulation system. Consequently, the history of Eirik Drift is a potential indicator of changes in ocean circulation that could provide forecasts of changes in ocean circulation expected in a warming world. Patterns of sediment accumulation across Eirik Drift in time and space were mapped using multi-channel seismic profiles collected during cruise KN166-14 of the R/V Knorr. These data were tied to the lithology, physical properties, and sedimentation rates of IODP Sites U1305, U1306 and U1307, and ODP Site 646. This analysis concludes that drift building began at 7.5 Ma and continues to the present, but did not follow a uniform history. Widespread seafloor erosion in the Late Miocene was followed by significant buildup in the mid-Pliocene that developed much of the form of Eirik Drift seen today. Growth of the Drift slowed during the Pleistocene with variations apparently tied to glacial-interglacial rhythms. Throughout this time, the flow of NADW varied in speed and depth in response to changing climate regimes, modifying the shape and distribution of the drift due to the interplay between changes in sediment supply, ocean circulation, and atmospheric temperatures. Our findings are consistent with other measurements and models of the history of NADW and North Atlantic Ocean circulation and atmospheric conditions.