Applications of Remote Sensing to Tectonics and Glacial Processes in the Saint Elias Orogen
Authors: Bruhn, R.L., Forster, R.R., Ford, A.L.J. and Pavlis, T.L.
Conference: American Geophysical Union Annual meeting
Dates: 6-10 December 2002
Abstract:The Saint Elias orogen provides a natural laboratory to evaluate the interrelationships between tectonics, glaciation and erosion. Geological investigations have demonstrated that several large alpine and piedmont glaciers flow along major tectonic boundaries that segment the orogen into regions of different structural style. For example, the Seward Glacier is located at the northwestern end of the Fairweather transform fault, the Malaspina Glacier flows onto the piedmont where it is bounded by the hanging wall of the Malapsina fault system, and the Bering Glacier bounds a region of superposed folding at the western end of the orogen. We are applying several remote sensing techniques to complement previous geological studies. The purpose is to investigate effects of bedrock structure on glacier flow, determine the locations of structural boundaries beneath the ice, and further determine the nature of folding and faulting throughout the orogen. The instruments and techniques include synthetic aperture radar (SAR) and interferometric analysis thereof (InSAR), newly released digitial elevation data from the Shuttle Radar Topography Mission (SRTM), and optical imagery from Landsat's TM/ETM and Terra's ASTER instruments. Significant observations with respect to glacial features and processes include: 1) Splay faulting at the northwestern end of the Fairweather fault disrupts the Seward Glacier basin causing flow of the Seward Glacier to be diverted southward toward the Saint Elias range front where the ice abuts a faulted bedrock ridge (Ford, Forster and Bruhn, Ann. Glac., in press). 2) Linear topographic depressions on the surface of the Malaspina Glacier form a trellis pattern that is inferred to reflect sub-glacial meltwater channels that are clearly important for the dispersal of eroded sediment from beneath the glacier although their origin remains enigmatic (Ford, Bruhn and Forster, this meeting). Remote sensing also provides insight into regional structure including the spatial distribution and style of superposed folding, down-plunge views into the cores of large-scale folds, and the locations of fault scarps and uplifted shorelines. Work in progress includes detailed modeling of the strain field responsible for superposed folding at the western end of the orogen, and further study of the Bering Glacier to determine how its location and flow may be affected by subjacent structures.
http://www.agu.org/meetings/fm02/
Source: Manual
Preferred by: Andrew Ford