QRC members lead and participate in a wide range of disciplinary and interdisciplinary research projects from the study of past earth climates and glaciations to shifts in the geographic distributions and evolution of vegetation and faunal communities, to the evolution and dispersals of the genus Homo and the increasing scales of human modification of earth environments through the Holocene. QRC provides a venue for meeting and collaborating with scholars across Quaternary disciplines. We are also fortunate to be able to provide seed funding and small grants for member research projects. We are especially happy to support grad student and junior scholar research activities, much of which leads to larger, external funding from agencies like the National Science Foundation.
Constraining past Antarctic Ice Sheet thickness using cosmogenic 14C in bedrock
Abstract: During the last glaciation, a grounded ice sheet filled the Ross Sea of Antarctica, where the Ross Ice Shelf exists today. This ice sheet began to thin around 13 kyr BP, and the transition from grounded to floating ice retreated inland towards its present position. We have mapped and dated glacial deposits alongside Darwin and Hatherton Glaciers, which record this thinning. Our new exposure ages suggest that the ice sheet remained grounded here until <3 kyr BP, which changes our understanding past ice flow in this region. Unfortunately, there was no clear limit of deposition at the mouth of Darwin Glacier, so we were not able to determine the thickness of the ice sheet at this location. We therefore will use cosmogenic 14C in a bedrock elevation transect from the mouth of Darwin Glacier, adjacent to the former Ross Sea Ice Sheet, in order to constrain the ice thickness during the last deglaciation. Due to the short half-life of this isotope, the concentration of 14C in rock reaches saturation within 30 kyr. Burial by ice would shield the rock from cosmic rays, shutting down the production of 14C. Even just a few thousand years of past ice cover will drastically reduce the concentration. Thus, if a given rock is saturated with respect to 14C, it could not have been covered by ice for any considerable amount of time in the last 30 kyr. If a rock contains less than the saturation concentration of 14C, then this suggests it was buried by ice during the last glaciation. Therefore, the respective elevations of the highest unsaturated sample and the lowest saturated sample will constrain the former ice sheet surface. We will use these data along with our chronology from nearby glacial deposits as constraints on a numerical ice-flow model in order to investigate the time at which the ice sheet began to thin at the mouth of Darwin Glacier.