Resumen de Effects of the subducting Nazca Ridge on Andean Exhumation in Southcentral Peru
M. Wipf, D. Seward, Fritz Schlunegger
The subduction of oceanic lithosphere with strong relief such as a ridge may produce superimposed tectonic effects on continental margins (von Heune et al„ 1991). Because these ridges are generally believed to have been sourced at hotspots on or near a midocean ridge, they tend to be aseismic and more buoyant than the surrounding ocean floor. Consequently, where they enter the subduction zone they have an initial and profound effect on the geomorphology of the associated trench. Furthermore the subduction of a buoyant aseismic ridge is likely to result in enhanced rates of exhumation o f the upper crustal sections of the overlying slab compared to neighbouring areas, and in a rerouting of rivers as the buoyant ridge possibly causes an anomaly in the crustal uplift pattern. It is these effects that we intend to quantify.
South-central Peru (12-18°S) provides an ideal position for such a study as it combines “normal “ subduction of the Pacific Plate with an intervening ridge subduction. Additionally, the Coastal Batholith in Peru offers the possibility to study the effects of one lithological unit in one climate zone (desert) therefore decreasing the parameters that might influence the results.
