Temporal Variation in Climate and Tectonic Coupling in the Central Andes
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Ehlers, Todd A.
Barnes, Jason B.
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CitationMcQuarrie, Nadine, Todd A. Ehlers, Jason B. Barnes, and Brendan Meade. 2009. Temporal variation in climate and tectonic coupling in the central Andes. Geology 36(12): 999-1002.
AbstractAnalog and numerical models predict a coupling between climate and tectonics whereby
erosion infl uences the deformation of orogens. A testable prediction from modeling studies is
the decrease in width of mountain ranges as a result of increased precipitation. Here we evaluate
the effect of climate on a critically tapered orogen, the central Andes, using sequentially
restored, balanced cross sections through wet (15°–16°S) and dry (21°S) regions of the orogen.
In these regions, tectonics, basin geometry, and style of deformation are similar, allowing us
to use variations in propagation (or changes in percent shortening) to evaluate whether alongstrike
changes in width and morphology are climate driven in the north. Results indicate similar
total percent shortening along the northern (40%) and southern (37%) sections, suggesting
that a wetter climate has not limited the width (propagation) in the north. However, comparison
of early (45–25 Ma) and recent (ca. 20–0 Ma) shortening indicates that early deformation
produced 45% ± 2% shortening of both sections, while recent deformation produced
41% ± 2% (north) versus 32% ± 2% (south) in the actively deforming Subandes. The latter
suggests a coupling between climate and tectonics that began between ca. 19 and 8 Ma, and
continues to 0 Ma, potentially limiting the width of the northern Subandes by ~40 km.
Citable link to this pagehttp://nrs.harvard.edu/urn-3:HUL.InstRepos:3354163
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