40Ar/39Ar constraints on the tectonic evolution of the late Paleozoic and early Mesozoic accretionary complex of coastal central Chile

Integrated structural and 40 Ar/ 39 Ar geochronologic analyses of basement rocks exposed along the north-central coast of Chile (~ 33.5°S) allow a reconstruction of a multistage history of magmatism, metamorphism, and deformation since the late Paleozoic. Each phase of ductile deformation documented from the Late Carboniferous-Late Jurassic is inextricably linked to coeval magmatism or melt infiltration. A regionally recognized NW-WNW-striking structural architecture, formed initially in the Late Carboniferous during intrusion of the igneous Santo Domingo Complex, modulated subsequent phases of deformation and magmatism during periods of oblique convergence. All together, the new data document a punctuated history of subduction, arc magmatism, accretion, and segmentation along the proto-Pacific margin of Gondwana and development of the Andean margin. Because the reactivation of NW-striking structures during great earthquakes is recognized regionally, the results of this work are pertinent to a holistic understanding of seismic hazards in suprasubduction zone settings.