HR: 0800h
AN: C51A-0264    [Abstracts]
TI: Fracture Patterns and the Reconstruction of Grounding Zone Dynamics on the Ross Ice Shelf, Antarctica
AU: * Fines, A K
EM: finesa@pdx.edu
AF: Portland State University, Department of Geology 1720 SW Broadway, Portland, OR 97201 United States
AU: Hulbe, C L
EM: chulbe@pdx.edu
AF: Portland State University, Department of Geology 1720 SW Broadway, Portland, OR 97201 United States
AU: Cruikshank, K M
EM: CruikshankK@pdx.edu
AF: Portland State University, Department of Geology 1720 SW Broadway, Portland, OR 97201 United States
AB: Fractures observed on the Ross Ice Shelf document a 1000 year history of the time-varying stress state within the shelf. The outlet area at Kamb Ice Stream is a site of recent, large amplitude change. Fractures that have formed in this region record variations of grounding line location, shear margin activity, and ice flux. Here, fracture analysis methods from structural geology are used to study that history. We limit out study area to a downstream distance of 60 km so that distortions due to ice advection are limited and fracture patterns represent primarily changes in stress state. Mapped fracture geometries are compared with stress trajectory maps for present-day ice shelf conditions. Where the two disagree, either near-field interactions among fractures has modified the propagation direction or past changes in the stress state are implied. We distinguish between these three possibilities and develop scenarios for past stress states in the Kamb outlet area. Paleo-stress states can, in turn, be used to infer past activity of Kamb and adjacent ice streams and past grounding line locations.
DE: 0728 Ice shelves
DE: 0730 Ice streams
DE: 0774 Dynamics
DE: 8010 Fractures and faults
SC: Cryosphere [C]
MN: Fall Meeting 2005