Crustal structure of the Lazufre volcanic complex and the Southern Puna from 3-D inversion of magnetotelluric data: Implications for surface uplift and evidence for melt storage and hydrothermal fluids

The Central Andes are unique in the global system of subduction zones that a significant, high-altitude plateau has formed above zone. In this region, both and associated magmatism have been shown to vary space time. Geophysical data invaluable determining subsurface structure region. Extensive seismic studies determined regional-scale distribution partial melt crust upper mantle. Magnetotelluric effective providing independent constraints on quantity composition Geodetic small number volcanic centers exhibit persistent, long-term uplift may indicate formation plutons or future eruptions. This paper describes detailed study Southern Puna using magnetotelluric (MT) data. region is located at southern limit where recent transition from flat-slab normal caused an increase magmatism, addition hypothesized lithospheric delamination. It also extensive zone adjacent arc undergoing surface uplift, near Volcán Lastarria Cordon del Azufre (collectively called Lazufre). main goals work define crustal investigate processes cause relatively large regions not with active volcanism. As part PLUTONS project, MT were collected east-west transect (approximately along 25°S) extended across Puna, Lazufre north Cerro Galan. combined previously around inverted give 3-D resistivity model crust. low resulted limited sensitivity mantle structure. A major conductors detected included (1) mid-crustal conductor extending eastward as far Salar de Antofalla; (2) upper- Galan; (3) rises westward terminates directly beneath Lazufre. These broadly coincident location lowshear-wave anomalies. conductive features interpreted be due stored crust, petrological used estimate fractions. Below Lazufre, it likely aqueous fluids contribute high conductivity, which observed within depth range inflation source, giving evidence magmatic hydrothermal processes.