麻豆传媒

The Kingnait Moraine system in western Foxe Peninsula, Baffin Island marks the ice margin position before the final wasting of glacial ice in the area. This area of Baffin Island is of particular interest due to its proximal location to both the Hudson Strait and the Foxe Basin, two locations which controlled local ice dynamics. Ice movement in this region also may have major implications for Heinrich Events in the north Atlantic region. Cosmogenic 10Be exposure dating was used to date both boulders perched on esker crests as well as a depth profile taken through the topsets of a glaciomarine delta at 151 m asl. Boulder exposure ages on eskers crests, bracketing the moraine, yield maximum ages of 8.9 + 0.5 ka and 6.9 + 0.4 ka (2 precision) indicating that the moraine was likely formed following the Cockburn event (9.6 ka) though possibly in response to the 8.2 Arctic cooling event or the Noble inlet advance (8.9-8.4 ka). This agrees with a mean exposure age of 7.5 + 1.4 ka for the abandonment of a sampled glaciomarine delta approximately 80 km to the southeast, which is down ice from the moraine. The exposure ages represent the first known esker exposure ages and demonstrate an important advancement in delta chronologic technique. Recent 14C ages of marine shells (Utting et. al., in press Feb., 2007) further support this conclusion.

Keywords: Moraine, Esker, Cosmogenic Nuclide, Glaciomarine Delta, Ice Stream
Pages: 62
Supervisor: John Gosse