Glacial History of Ridge AB, West Antarctica

University Of Washington, Seattle WA

Investigators

Abstract

0087144 Conway This award supports the study the glacial history of Ridge AB in West Antarctica using well-established geophysical methods. Our study is motivated by the need to improve under-standing of how the configuration and activity of the West Antarctic drainage system is changing, and how this affects the stability of the ice sheet. Ridge AB has been chosen for several reasons: 1) previous studies of inter-stream ridges in West Antarctica have revealed much information about the history of the surrounding ice streams. There is an "information-hole" in the southern sector of the ice sheet; we are optimistic that our study of Ridge AB will reveal new information about recent changes in the configuration and activity of Ice Streams A and B; 2) geologic evidence from Reedy Glacier indicates that ice in the vicinity of Ridge AB was ~700 m thicker during the last glacial maximum. This helps constrain the magnitude of thinning that has occurred through the Holocene, and opens the possibility of linking the history of the West Antarctic Ice Sheet to the geologic record in the Trans-Antarctic Mountains. Our approach is to first map spatial variations of internal layering, buried crevasses, surface velocity, and accumulation rate. The main investigative tools are: high and low-frequency radar systems, GPS surveying methods, and short (20 m) firn cores. The diagnostic measurements will then be examined with ice flow models to infer the glacial history of Ridge AB and the surrounding ice streams. The history will be interpreted in context of the histories that are emerging from the other inter-ice stream ridges, as well as the geologic evidence from Reedy and other outlet glaciers in the Trans-Antarctic Mountains. Our overall goal is to improve understanding of the evolution of the WAIS drainage system.