Thursday, November 10, 2011, 4:30AM - 5:30AM
The Greenland Ice Sheet (GIS) is the last remaining Northern Hemisphere ice sheet and arguably the most important archive of Late Quaternary and Holocene Northern Hemisphere climate. A record of ice-sheet and ice-stream history, ice-sheet ocean interactions, and paleoclimate is preserved offshore of the GIS in the sediments of the Umanak fjord, shelf trough and trough mouth fan system of West Greenland. During cruise JR175 of the UK ship RRS James Clark Ross in 2009, sediment cores and geophysical data were collected from the Umanak System to document the glacial history of the area. SWATH bathymetry data show that the Greenland Ice Sheet extended to the shelf edge via an ice stream in the Umanak System of West Greenland during the Last Glacial Maximum (LGM). The objective of this study is to document the timing and rate of ice retreat, and the role of the West Greenland Current (WGC) in initiating or sustaining ice retreat. This talk presents preliminary analyses of a transect of 4 cores from the upper slope to the inner Umanak shelf trough collected during JR175. Preliminary evidence will be presented for changes in environmental conditions as the core sites transitioned from subglacial to ice-proximal to open water from the LGM through the Holocene. With the knowledge that warm Atlantic Water impinging on the marine margins of the present-day GIS is speeding ice sheet retreat, this project is investigating the past interactions between the Umanak Ice Stream and the WGC through analysis of foraminiferal assemblages and stable isotopes on foraminifera.