Oligocene to present shallow subduction beneath the southern Puna plateau

Upper Plate Controls on the Formation of Broken Foreland Basins in the Andean Retroarc Between 26°S and 28°S: From Cretaceous Rifting to Paleogene and Miocene Broken Foreland Basins

“…Therefore, we suggest that upper plate pre-Miocene structures were the main precursor of the along-strike segmentation observed in the study area. Herein, we show that the along-strike segmentation of this portion of the Andes predates Late Oligocene to Miocene flat-slab subduction (26 Ma, Gianni et al, 2020) and controlled the subsequent deformation style. These conclusions imply that Late Oligocene-Miocene slab flattening was not responsible for the along-strike segmentation and the deformation patterns of the northern limit of the Sierras Pampeanas.…”

“…Farther north in the Central Andes (~22–24°S), Eocene to Oligocene retroact deformation was coeval with a period of flat‐slab subduction (Haschke et al, 2002; Horton, 2018b; Martinod et al, 2020). However, between 26°S and 28°S, the Eocene to Oligocene magmatic arc remained on the Western Cordillera, suggesting Paleogene normal subduction in this segment of the Central Andes (Gianni et al, 2020). Therefore, in our study area, flat‐slab subduction was not the main precursor of the documented eastward migration of deformation during the Eocene.…”

“…This model predicts that flat‐slab subduction commenced beneath the study area (26–28°S) around 12 Ma. However, Gianni et al (2020) suggested that between 25°S and 28°S flat‐slab subduction started at ~26 Ma. The formation of the Sierras Pampeanas and the Santa Barbara broken foreland basins has been directly related to Late‐Oligocene to Miocene flat‐slab subduction (Carrapa et al, 2008; Gianni et al, 2020; Jordan et al, 1983; Ramos & Folguera, 2009).…”

“…The Eocene to Oligocene tectonic evolution of the Central Andean retroarc between 25°S and 30°S has been extensively discussed. Several authors postulated that the Central Andean retroarc was undeformed and constituted a distal segment of a continuous foreland basin formed during a period of steep subduction (Carrapa et al, 2008;DeCelles et al, 2011;Gianni et al, 2020;Zhou et al, 2017). Alternative models proposed that Paleogene deformation in the Central Andean retroarc formed disconnected basement highs that characterize a broken foreland basin (del Papa et al, 2013;Hongn et al, 2007;Payrola et al, 2009).…”

Architecture, Kinematics, and Tectonic Evolution of the Principal Cordillera of the Andes in Central Chile (∼33.5°S): Insights From Detrital Zircon U‐Pb Geochronology and Seismotectonics Implications

“…At the end of the Early Cretaceous, a change in the tectonic regime, linked to a change in the convergence vector (Coney & Evenchick, 1994; Gianni et al., 2020; Somoza & Zaffarana, 2008), would have driven the Late Cretaceous compressive event (Bascuñán et al., 2015; Charrier et al., 2007; Steinmann, 1929). This would have been coetaneous to the opening of the South Atlantic and the subduction of the mid‐ocean separating the Chasca‐Catequil plates underneath the proto‐South American continent (Gianni et al., 2015; Somoza & Zaffarana, 2008).…”