Large-scale Cenozoic Wind Erosion in the Puna Plateau: The Salina del
Fraile Depression
Abstract
Wind erosion is integral to the evolution of arid landscapes on Earth
and Mars, but the nature of long-term wind erosion of bedrock is poorly
understood. Here we describe the Salina del Fraile (SdF) depression in
the Puna Plateau of the Central Andes, NW Argentina, as a landform
excavated by wind over several million years. New structural
cross-sections and a compilation of chronostratigraphic ages rule out
the hypothesis that the depression was created by transtensional
tectonics. Dated remnant lacustrine and alluvial deposits in the floor
of the depression constrain the rate and timing of erosion. Late
Oligocene–Miocene compressional folding uplifted friable strata that
were preferentially eroded, resulting in the high-relief (900 m)
depression. Up to 1.95 km and an average of 1.05 km of strata were
eroded during the last 8.2 to 17 Ma, at rates of 0.06 to 0.23 mm/yr.
These rates are similar to long-term average wind erosion rates reported
in other regions. Coarse-grained eolian megaripples, yardangs, and
elongated ridges indicate ongoing eolian abrasion and deflation, aided
by salt weathering, of the floor of the depression. Megaripple migration
across stony lag surfaces exposes fresh bedrock to continued erosion.
The SdF also contains kilometerscale mesas and ridges that we interpret
as erosional remnants. These landforms are similar to megayardangs and
erosional topography identified on the lower flanks of Mount Sharp, Gale
crater, Mars. In such hyperarid landscapes characterized by lithologic
heterogeneities, high relief landforms can be generated and sustained by
wind erosion, without significant fluvial or glacial incision.