Net land subsidence in Northwest Greenland during the Holocene
with Karlee Prince, PhD Candidate, University of Buffalo.
Abstract: Observations of paleo-sea level are essential for data-model comparisons that increase confidence in ice-sheet models and reduce uncertainty in future sea-level rise projections. To fill an important spatial data gap and investigate the unexpectedly low marine limit in NW Greenland, we used isolation basins and marine basins to constrain the relative sea level history at Aappilattoq. In sediment cores from three lakes at 22.0, 16.9, and 6.9 m above mean sea level we found lacustrine sediments overlying deglacial sediments with no marine sediments. In sediment cores from three marine basins with sill depths 6.7, 2.4, and 0.2 m below mean sea level, we found marine sediments overlying lacustrine sediments that cap deglacial sediments. We use modern tidal data to determine paleo-mean-sea-level and radiocarbon results from sediment ingression contacts to find that mean sea level was 8.0 m bsl at 5.5 ± 0.1 cal ka BP, reached 3.7 m bsl at 1.5 ± 0.2 cal ka BP, and reached 1.5 m bsl at 0.7 ± 0.2 cal ka BP. Thus, the marine basins were lakes until inundated by local sea level rise, and modern sea level marks the marine limit at Aappilattoq. We hypothesize that Aappilattoq lies on a subsiding forebulge of the Laurentide, Innuitian and Greenland Ice Sheets. Despite the relatively thick ice cover over Aappilattoq during the Last Glacial Maximum, mantle material was transported into the area because of the configuration of regional ice sheet loading. Further investigations of a potential ice-sheet and GIA feedback of shallowing ocean floors during advances and subsidence during retreat are important to understand Greenland Ice Sheet behavior during the Last Glacial Maximum.
