Fission track thermochronology of Neogene plutons in the Principal Andean Cordillera of central Chile (33-35°S): Implications for tectonic evolution and porphyry Cu-Mo mineralization

Abstract

AbStRACt. Apatite fission track data for Miocene plutons of the western slope of the Principal Andean Cordillera in central Chile (33-35°S) define a distinct episode of enhanced crustal cooling through the temperature range of the apatite partial annealing zone (~125-60°C) from about 6 to 3 Ma. This cooling episode is compatible with accelerated exhumation of the plutons at the time of Pliocene compressive tectonism, and mass wasting on the western slope of the Principal Andean Cordillera in central Chile. The timing coincides with the southward migration of the subducting Juan Fernández Ridge and the development of progressive subduction flattening northward of 33°S. It also corresponds to the time of active magmatic-hydrothermal processes and rapid unroofing of the world class Río Blanco-Los Bronces and El Teniente porphyry Cu-Mo deposits. Zircon fission track ages coincide with previous 40 Ar/ 39 Ar dates of the intrusions, and with some of the apatite fission track ages, being coherent with igneous-linked, rapid cooling following magmatic intrusion. The thermochronologic data are consistent with a maximum of about 8 km for Neogene exhumation of the plutons.

The Distribution and Timing of Molybdenite Mineralization at the El Teniente Cu-Mo Porphyry Deposit, Chile

“…The tectonic setting, regional geology and magmatic-hydrothermal evolution of El Teniente have been the focus of numerous studies over the last 90 years (Lindgren and Bastin, 1922;Howell and Malloy, 1960;Camus, 1975;Charrier et al, 2002;Skewes et al, 2002;Maksaev et al, 2004Maksaev et al, , 2009Cannell et al, 2005Cannell et al, , 2007Skewes and Stern, 2007;Klemm et al, 2007;Rabbia et al, 2009;Astudillo et al, 2010;Stern et al, 2010;Vry et al, 2010;Muñoz et al, 2012). Combined, these investigations have helped build an understanding of the magmatic and hydrothermal evolution of the deposit.…”

“…Maksaev et al, 2004Maksaev et al, , 2009Vry et al, 2010). Three vein chronologies have been formulated using vein cross-cutting relationships, each identifying at least 13 distinct vein types (the El Teniente mine classification used since 2003; Cannell et al, 2005;Vry et al, 2010).…”

Nuevos antecedentes estratigráficos y geocronológicos para el Meso-Cenozoico de la Cordillera Principal de Chile entre 32° y 32°30’S: Implicancias estructurales y paleogeográficas

“…1) se ubica en el límite sur de la zona de subducción subhorizontal Pampeana o Chilena que se desarrolla entre ~27° y 33°S (Cahill e Isacks, 1992;Ramos, 1999;Gutscher et al, 2000;Ramos et al, 2002). Al sur de la zona de estudio (al sur de 33°S), en la parte norte del segmento de subducción normal, los depósitos del Eoceno superior al Mioceno inferior han sido estudiados desde la década del 60 y se ha interpretado el ambiente tectónico en que se habrían originado, mediante la caracterización de los depósitos, las estructuras que los afectan, su geocronología y geoquímica, entre otras metodologías (Aguirre, 1960;Thiele, 1980;Aguirre et al, 2000;Charrier et al, 1996Charrier et al, , 2002Godoy et al, 1996Godoy et al, , 1999Sellés, 1999Sellés, , 2000Zurita, 1999;Rivera y Cembrano, 2000;Giambiagi y Ramos, 2002;Nyström et al, 2003;Fock et al, 2005;Fock et al, 2006a, b;Muñoz et al, 2006;Jara et al, 2009a, b;Maksaev et al, 2003Maksaev et al, , 2009Armijo et al, 2009;Farías et al, 2010;Rauld, 2011, entre otros). Estos estudios han permitido asignar las rocas de la Formación Abanico (Fig.…”

Migrating deformation in the Central Andes from enhanced orographic rainfall

“…Our hypothesis predicts the largest changes south of the region from the Beni basin where rainfall rates decrease from > 3500 mm per year at 16 ° S, to the Pilcomayo basin at 20 ° S with ca 1000 mm per year, as seen by the shift towards low channel concavities and gradients 14 . Th is is indeed supported by northsouth reversal trends of apatite fi ssion track ages 26,44,52,53 , and a series of left -lateral transtensional faults ( Fig. 1a ).…”