Sediment routing system response to tectonic activity in the Argentine Precordillera : Sierra Las Penas-Las Higueras
Abrahamson, Ingrid Syverine
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Alluvial fan deposition in the Argentine Central Precordillera is part of a sediment routing system that changes along strike of an active thrust front. This study area is partitioned into erosional and depositional sectors for analysis. The erosional sector drainage basins are analyzed using topographic data from a digital elevation model, to see how morphology changes with fault displacement. Drainage basins become shorter with more displacement. The depositional sector alluvial fans are classified using spectral characteristics from satellite imagery. The fans are classified based on thermal, near infrared, and elevation parameters. Fans close to the thrust front are interpreted to be old sheetflood deposits, with younger fans more distal from the front in the foreland. In this setting, progressive fault displacement causes shortening of the erosional sector, increasing the efficiency of sediment evacuation from the range, and causing a progradation of sheetflood fans into the foreland basin. Remote sensing analysis techniques are useful for characterizing the sediment routing system of alluvial systems where field-based information (geodetic, seismic, structural and lithologic data) is not available.