Tectonic evolution of the North Patagonian Andes from field and gravity data (39–40°S)

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

“…Jurassic‐Cenozoic arc magmatism is embodied by the North Patagonian Batholith, which makes up most of the elevated topography in the main range, and a broad retroarc zone characterized by several igneous provinces (Pilcaniyeu and El Maitén belts) (Castro et al, ; Hervé, ; Pankhurst et al, ; Rapela et al, ). An estimated crustal thickness of up to ~32 km reflects only 10–20 km of shortening, consistent with limited large‐scale thickening via shortening or magmatic addition (Echaurren et al, ; Orts et al, , ; M. Ramos et al, ; Tassara & Echaurren, ).…”

“…Trench‐normal absolute overriding plate velocity has been identified as a first‐order plate‐scale driver of Andean orogenesis (e.g., Coney & Evenchick, ; Maloney et al, ; Mpodozis & Cornejo, ; Oncken et al, ; Ramos, ; Schellart, ; Silver et al, ; Sobolev et al, ; Sobolev & Babeyko, ; Somoza & Zaffarana, ; Vietor & Echtler, ). Phases of flat slab subduction are well recognized to correlate with spatial variations in Andean magmatism and deformation (Gutscher et al, ; Jordan et al, ; Ramos et al, ; Ramos & Folguera, ), including potential cyclical behavior involving an inboard sweep of shortening and arc magmatism during slab shallowing and neutral to extensional conditions during slab resteepening (e.g., Ramos, ; Ramos et al, ).…”

“…During the Neogene, retroarc shortening in a narrow fold‐thrust system was governed by reactivation of earlier Cenozoic extensional structures, with only 10–20 km of shortening and minor deformation in distal regions of the broken foreland (Giacosa et al, ; Giacosa & Heredia, ; Orts et al, , ; Savignano et al, ). Associated wedge‐top and foreland basin development is marked by the Ñirihuau and Collón‐Curá Basins, including documented growth strata along associated thrust faults (Bechis et al, ; Bilmes et al, ; Echaurren et al, ; García Morabito & Ramos, ; Giacosa et al, ; Huyghe et al, ; Orts et al, ; Paredes et al, ; M. Ramos et al, ). In the arc to forearc region, dextral offset along the north striking Liquiñe‐Ofqui fault zone initiated by late Miocene time, as a product of strain partitioning during oblique subduction and further modification by ridge collision during Pliocene‐Quaternary time (Cembrano et al, , ; Thomson, ).…”

“…For example, extreme crustal shortening appears to have been confined to the axis of the central Andes at 15–25°S (including the “Bolivian orocline”; Gephart, ; Isacks, ; Kley & Monaldi, ; McQuarrie, ), with accompanying episodic or cyclical removal of thickened orogenic roots (DeCelles et al, , ). In addition, transient shallowing and steepening of the subducting slab has exerted an important influence on orogenic patterns along specific segments of the plate boundary (Haschke et al, , ; Kay et al, ; Kay & Coira, ; Ramos et al, , ; Ramos & Folguera, ).…”

Phylogenetic insights into Andean plant diversification

“…Such nonuniform spatial patterns of uplift have also been suggested for the Northern Andes (Hoorn et al, 1995). For the Southern Andes, Blisniuk et al (2005) indicates that most of the uplift would have occurred by 16.5 Ma, earlier than most of the Central Andes, and several studies are in line with the idea of an Early Miocene uplift of the Southern Andes (e.g., Jordan et al, 2001;Encinas et al, 2013;Fosdick et al, 2013), but Late Miocene phases of uplift have also been reported for the northern Patagonian Andes (Ramos et al, 2014).…”