Along-strike segmentation of the Abanico Basin, central Chile: New chronological, geochemical and structural constraints

Apatite (U–Th)/He thermochronology and Re–Os ages in the Altar region, Central Andes (31°30′S), Main Cordillera of San Juan, Argentina: implications of rapid exhumation in the porphyry Cu (Au) metal endowment and regional tectonics

“…At this time there is clear evidence of tectonic activity in the Altar-Pelambres region where field relationships indicate that the Pelambres Fault was active as a thrust fault between 18 and 14 Ma (Mpodozis et al 2009;Perelló et al 2012). This event has been also well recognized in Chile and Argentina south of 32°S (Giambiagi et al 2012;Piquer et al 2017;Buellow et al 2018) matching with the beginning of deformation and collapse (inversion) of the extensional Abanico-Coya Machalí Basin (Charrier et al 2002(Charrier et al , 2005Piquer et al 2017) (Jordan et al 1996;Pérez 2001;Alarcón and Pinto 2015).…”

“…At Altar they include a lower unit of basaltic andesite and porphyritic andesite-dacite lavas, andesitic-dacitic lapilli tuff, and pyroclastic breccia that grade upwards to a unit of compact and thick rhyolitic tuff (U-Pb zircon ages of 21.6 ± 1.2 Ma and 20.8 ± 0.3 Ma, Maydagán et al 2011;Maydagán 2012). Both the Pachón Formation and the Mondaca Strata are, in part, equivalent to the regionally extensive volcanic Abanico/Coya-Machalí formations that form the bulk of the main Cordillera of Central Chile (33°-36ºS, Aguirre 1960;Klohn 1960;Thiele 1980;Charrier et al 2002;Piquer et al 2017).…”

Southward-Directed Subduction of the Farallon–Aluk Spreading Ridge and Its Impact on Subduction Mechanics and Andean Arc Magmatism: Insights From Geochemical and Seismic Tomographic Data

“…(2) For the second magmatic period, between the Paleocene and the Eocene (59-37 Ma), we included arcrelated sequences emplaced between 36 • and 38 • S (PVNM) (Provincia Magmática Neuquino Mendocina; 56-38 Ma; Rapela and Llambías, 1985;Llambías and Rapela, 1989) and magmatism located along the Patagonian Precordillera between 40 • and 43 • S (Pilcaniyeu magmatic belt; 57-43 Ma) (Rapela et al, 1988;Aragón et al, 2011;Iannelli et al, 2017). (3) For the last magmatic period defined between the latest Eocene to the early Miocene (37-20 Ma) we considered from north to south, the volcanic sequences developed along intraarc basins mainly located between 33 • and 36 • S (Abanico Formation; 36-20 Ma; 33-36 • S; Kay et al, 2005;Muñoz et al, 2006;Montecinos et al, 2008;Piquer et al, 2017), magmatic units between 36 • and 38 • S (lower Cura Mallín Formation; 27-20 Ma; 36-39 • S; Burns et al, 2006;Kay et al, 2006;Utgé et al, 2009), and the arc-related sequences developed along the Central Depression between 37 • and 43.5 • S (Coastal Magmatic Belt, CMB; 28-20 Ma; López-Escobar and Vergara, 1997;Muñoz et al, 2000).…”

“…By the last magmatic period (37-20 Ma) Andean arc-like sequences show a more widespread and continuous distribution in comparison with the previous magmatic stages, as well as less pronounced geochemical differences. A regional comparison is made between studied Auca Pan Formation (29 Ma, 39 • S; Iannelli et al, 2017), the volcanic units of the Abanico Formation emplaced at 33-36 • S (36-20 Ma;Charrier et al, 2002;Kay et al, 2005;Muñoz et al, 2006;Piquer et al, 2017), the lower sections of the Cura Mallín Formation at 36-38 • S (27-20 Ma; Suárez and Emparán, 1995;Burns et al, 2006;Kay et al, 2006;Utgé et al, 2009), and the southern Coastal Magmatic Belt developed between 37 • and 43.5 • S (28-20 Ma;López-Escobar and Vergara, 1997; 2000; Figure 1).…”

“…Schematic diagram showing the main arc-related units used in the regional comparison. Geochemical data area from the following: for the first magmatic period (80-59 Ma): Casé et al (2008); De La Fuente (2014), Franchini et al (2003); Iannelli et al (2018), Llambías and Aragón (2011); Lucassen et al (2004), Mateo-Fernández Caso et al (2011); Muñoz et al (2018), and Zamora Valcarce et al (2006); for the second magmatic period (59-37 Ma): Aragón et al (2011); Iannelli et al(2017),Kay et al (2006), andLlambías and Rapela (1989); and for the last period (37-20 Ma):Iannelli et al (2017);Kay et al (2005)Kay et al (2006); López-Escobar and Vergara (1997),Piquer et al (2017), andUtgé et al (2009).…”