Title: Miocene extension of the hinterland Antofalla Basin, southern central Andes: Relationship to lithospheric foundering
Abstract: In the Southern Puna Plateau, NW Argentina, Miocene to Quaternary lithospheric foundering is inferred from a combination of backarc volcanism and geophysically imaged detached lithosphere. Anomalous tectonic extension or transtension may be key to better constraining the dynamics of foundering, but the timing and scale of such extension remains enigmatic. We present new mapping and geochronology that document Middle to Late Miocene extension of the Antofalla Basin, which is centrally located in the area affected by foundering.
The Antofalla Basin is a ~125 km long, ~800 m deep linear basin that trends NNE within the Southern Puna Plateau and is internally drained. New geologic mapping, stratigraphy, and geochronology from an exceptionally well-exposed part of the Antofalla area reveal a normal fault system that became active between 13 and 11 Ma and probably generated the relief observed in the modern basin.
The onset of extension >11 Ma at the Vega Antofalla locality is consistent with age estimates from the southern part of the Antofalla Basin based on the ages of basal evaporite strata within the basin, suggesting a common evolution for the entire basin. Extension of the Antofalla Basin several Myr before major backarc volcanism (ca. 8 Ma) is consistent with numerical models of lithospheric foundering.
Biography: I am a structural geologist and tectonicist interested in relationships between deformation, exhumation, and lithospheric evolution in mountain belts. I investigate these processes through geologic mapping, thermochronometry, detrital records, and cross section restoration. I am an assistant professor at Utah Tech University.
To join virtually: Zoom
Contact: alex.tye@utahtech.edu
Recording: Zoom Recording (will be available within a week after the seminar)