HR: 09:45h
AN: C41D-08    [Abstracts]
TI: Dating Ice Divides in West Antarctica by the Operation of the Raymond Effect
AU: * Hindmarsh, R
EM: rcah@bas.ac.uk
AF: Physical Science Division British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Navarro, F N
EM: fnv@mat.upm.es
AF: Departamento de Matem tica Aplicada ETSI de Telecomunicaci¢n,, Universidad Polit‚cnica de Madrid Ciudad Universitaria, Madrid, 28040 Spain
AU: Martin, C
EM: cmartin@mat.upm.es
AF: Departamento de Matem tica Aplicada ETSI de Telecomunicaci¢n,, Universidad Polit‚cnica de Madrid Ciudad Universitaria, Madrid, 28040 Spain
AU: Jacobel, B
EM: jacobel@stolaf.edu
AF: Physics Department, St.Olaf College 1520 St.Olaf Ave, Northfield,, MN 55057 United States
AB: Once an ice-divide forms, isochronic layers become locally upwarped through the operation of the well-known Raymond Effect. The distribution of bump-amplitude with elevation (BAE curve) evolves with time to a steady configuration that depends on the ice rheology, temperature, the accumulation rate and the chaning geomety of the ice mass. Unsaturated BAE curves can be used in principle to determine the age of the divide. We apply these techniques to several locations in West Antarctica, where isochrones have been located using radar echo sounding. Firstly, we repeat the investigations into Roosevelt Island reported by Conway et al (1998), using a more sophisticated set of calculations which include thermo-mechanical coupling. Their dating results can be obtained, but only with a relatively high rheological index. We next consider the divide in Marie Byrd Land between the Siple Coast and the Amundsen Sea Sector. Here the bump amplitudes are less than their theoretical saturated value, and we explore rheological and thermal hypotheses for this related to the likely presence of sliding. Finally we consider the Hercules dome. Here the bumps are shown to be comparable in size to their saturated steady state value.
DE: 1827 Glaciology (1863)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting