Abstract

In this contribution we examine the relationship between active compression and construction of Pleistocene volcanoes in the present-day magmatic arc of the central Andes (23°S-24°S). Deformation produced severalN-S striking,~40 km long subparallel ridges. These ridges formed by folding of Pliocene ignimbrites and upper Pliocene and Pleistocene lavas; they are asymmetrical in profile and have a gentle back limb and steeper frontal limb. Andesitic monogenetic volcanoes show a close spatial relationship with the ridges; some volcanoes are on the hinge zone, whereas others lay on the sides of the ridges. We interpret this spatial pattern as a result of magma storage and migration along a system of subhorizontal reservoirs and reverse faults. Magma reservoirs probably formed along flat portions of reverse faults between ramp structures that serve as episodic magma transport pathways. © 2009 by the American Geophysical Union.