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In order to ascertain the mechanisms of formation of a 20 to 150 m high, 300 km long, N-S trending escarpment located between 34o and 38o S, Argentina, geomorphometric analysis of parameters such as sinuosity, topography, and local fluvial evolution were used to study regional features produced through fluvial and tectonic evolution. Surficial units were mapped based on the interpretation of 3 arc second DEMs and available geologic maps in order to place the escarpment evolution into regional context. The sinuosity of the escarpment face was found to range from 1.1 to 1.3 in the northern section, between 1.5 to 1.7 in the central section, and from 1.3 to 1.5 in the southern section, indicating that incision of the scarp has been greatest in the central region. Analysis of fluvial knickpoints on streams flowing east over the escarpment reveal that a greater number of farther migration of knickpoints in the south than the north. The Rio Salado, which flows within 15 km along much of the escarpment, shows a significant knickzone situated near the central region. These and other geomorphometric analyses, mapped location of faults, and the interpretation of the regional topography suggests that this escarpment was formed though the parallel incision of the Rio Salado. The location and rate of Rio Salado incision was controlled by normal faulting and base level change. The local extension and consequent incision has also affected sedimentation patterns and incision history of major Andean streams that are tributaries of the Rio Salado.

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Pages: 68
Supervisor: John Gosse