COMPARING THREE NEW IRD MAR RECORDS FROM IODP EXPEDITION 341 IN THE GULF OF ALASKA
We propose that rocky, coarse-grained intervals in the drill core resulting in no recovery at Site U1421 are periods of glacial advance to the shelf edge. This interpretation is supported by analogous IRD MAR drops in Site U1419. Intervals of coincident IRD peaks suggest periods of glacial termini retreat along the Alaskan coast. During a period of Bering Glacier retreat, a short-term reduction in IRD MAR was observed at Site U1421. We propose that this was caused by sea ice expansion which may have trapped Bering Glacier icebergs on the shelf. Inconsistencies in IRD MAR peaks do occur between the three sites, potentially due to contributions from other coastal Alaskan tidewater glaciers, influences of oceanic currents, and varying local sea surface temperatures. Glaciers finally terminated at Site U1421 and U1419 at approximately 15.5 Kyr. Prominent peaks in IRD MAR at Sites U1419 and U1417 are coincident with Heinrich event 1 (H1), but the response to H2 and H3 is less apparent.