Plate tectonic setting of the Andean Cordillera

Abstract

The Andes are a natural laboratory for the study of the interaction between subduction of the oceanic plate and active geological processes. Inter-and intraplate seismicity, volcanic activity, thick-and thin-skinned fold and thrust belts, and foreland basin subsidence, in conjunction with space geodetic observations, contribute to characterize the present plate tectonic setting of discrete segments of the Andes. The inherited geological history, as well as the present tectonic setting, is responsible for the unique geology of the Northern, Central, and Southern Andes. The Northern Andes are the result of Mesozoic and Cenozoic collisions of oceanic terranes, prior to the present Andean-type setting. The Central Andes have a long history of subduction and volcanic arc activity, while the Southern Andes record the closing of a back-arc oceanic basin, and almost no volcanic arc activity. These major geological units have along-strike variations in the subduction geometry that controls the different volcanic zones. The link between trench collision of aseismic ridges and flat-slab segments plays an important role in the conclusion of the volcanic activity. The collision of seismic ridges also produces a volcanic arc gap, but with an unusual suite of near trench magmatism, plateau basalts, and adakites.