HIGH RESOLUTION RECORDS OF ICE RAFTED DEBRIS AT ODP SITE 980 NORTHEAST ATLANTIC OCEAN DURING MARINE ISOTOPE STAGES 4-2

Recovery of high sedimentation rate deep-sea sediment sections from the North Atlantic have resulted in several studies demonstrating that climate instability at millennial time-scales is a pervasive component of Late Pleistocene North Atlantic climate. This is particularly true during Marine Isotope Stages (MIS) 4-2. One such high sedimentation rate section was recovered at ODP Site 980, Northeast Atlantic Ocean where sedimentation rates during MIS 4-2 exceed 15cm/kyr. We have recently reduced our sampling interval at site 980 from 20 to around 2.5 cm, improving the resolution of our records an order of magnitude, from 1200-1300 to 100-200 years. 245 samples from MIS 4-2 were used to generate 2 proxies that document changes in the input of ice-rafted detritus (IRD), % lithics, >150mm and lithic grains, >150mm per gram sediment. These high resolution IRD records can be evaluated within the context of our previously generated lower resolution benthic oxygen isotope record used to generate our age model for this interval. Our previously published low resolution IRD record enabled us to identify Heinrich events 1-6 within the sediment intervals deposited during the last glacial. Each event is characterized by IRD concentrations ranging from 800 to over 2500 lithic grains per gram and 30% to over 65% lithics. Our new high resolution IRD records of Heinrich events 3,2,1 occurring at approximately 32, 23, and 17 kya, are each composed of a series of separate abrupt rapid increases in IRD concentrations approaching 1,500 lithic grains per gram and 65% lithics. In the early part of the last glacial H6, H5, and H4, occurring at approximately 66, 47, and 38 kya, respectively, are recorded as much more abrupt and rapid increases in IRD concentrations to 1,800 or greater lithic grains per gram, >30% lithics than previously observed in our low resolution records. Finally, our new IRD records record a series of additional abrupt increases in IRD concentrations comparable in intensity to identified Heinrich events. This suggests that ODP Site 980 sediments are recording a series of more closely spaced episodic increases in IRD concentrations that may be related to Dansgaard/Oeschger events recorded in Greenland ice cores.