HR: 09:00h
AN: C21A-05    [PDF]
TI: Glaciogeophysics at Matanuska Glacier, Alaska
AU: * Baker, G S
EM: gbaker@geology.buffalo.edu
AF: University at Buffalo, Dept of Geology, Buffalo, NY 14260 United States
AU: Lawson, D E
EM: Daniel.E.Lawson@erdc.usace.army.mil
AF: U.S. Army Cold Regions Rsch and Engineering Lab, 72 Lyme Rd, Hanover, NH 03755 United States
AU: Evenson, E B
EM: ebe0@lehigh.edu
AF: Lehigh University, Dept of Earth and Environmental Sciences, Bethlehem, PA 18015 United States
AU: Larson, G J
EM: larsong@pilot.msu.edu
AF: Michigan State University, Dept of Geological Sciences, East Lansing, MI 48824 United States
AU: Alley, R B
EM: ralley@essc.psu.edu
AF: Pennsylvania State University, Dept of Geosciences, University Park, PA 16802 United States
AB: Numerous near-surface geophysical studies on and near Matanuska Glacier, Alaska, have been used to test and develop hypotheses related to several important aspects of glacier margin dynamics. First, high-resolution seismic reflection data constrains the 3D distribution of debris-rich basal ice and have been used to confirm the predicted distribution determined by the basal freeze-on mechanism of sediment entrainment. Second, seismic reflection and refraction, GPR, and electrical resistivity data indicate the presence of extensive buried ice beneath the ice-proximal outwash plain. These data are used to hypothesize an alternative means for pitted-outwash plain formation that does not rely on the "buried block-of-ice" mechanism. Third, extensive GPR data collected on an ice-cored moraine complex--at the same site over a period of three years--indicate that the buried ice rigidly deformed in response to impact from re-advancing active ice. As a result (as imaged in 3D using the GPR and based on surface exposure) the overlying sediments in the ice-cored moraine deformed. This data is used to support the hypothesis that glaciotectonic deformation need not rely on stresses propagating through soft sediments; rather, buried ice can be a dominant mechanism in the deformation process. Finally, seismic reflection and refraction tomography are used to constrain depth-to-bedrock in the valley proximal to the glacier in order to constrain erosion and sedimentation rates.
UR: http://www.geophysics.buffalo.edu
DE: 0925 Magnetic and electrical methods
DE: 0935 Seismic methods (3025)
DE: 1824 Geomorphology (1625)
DE: 1827 Glaciology (1863)
DE: 7294 Instruments and techniques
SC: Cryosphere [C]
MN: 2003 Fall Meeting