Climatic control on the location of continental volcanic arcs

Orogens and volcanic arcs at continental plate margins are primary surface expressions of convergent plate tectonics. Although it is established that climate affects the shape, size, and architecture of orogens via orographic erosion gradients, the crustal upwelling of magmas and location of volcanic arcs have been considered insensitive to erosion. However, available data reveal westward migration of late-Cenozoic volcanic activity in the Southern Andes and Cascade Range where orography drives an eastward migration of the topographic water divide by increased precipitation and erosion along west-facing slopes. Here we use thermomechanical numerical modeling to show that orographic erosion and leeward topographic shift may entail asymmetric crustal structures, driving magma upwelling toward the region of enhanced erosion. Considering the different tectonic histories between the Southern Andes and the Cascade Range, the orographic erosion gradient is a plausible shared causal mechanism behind the late-Cenozoic westward migration of the regional volcanic arcs.