Linking geothermal systems in the framework of the Altiplano-Puna Magma Body (APMB), Central Andean Volcanic Zone, northern Chile.

Monday, 8 January 2018
Salon Maule (Hotel Quinamavida)
Benigno Godoy1, Estefanía Camus1, Claudia Cannatelli1, Daniel Diaz1, Loreto Hernández1, Juvenal Letelier1, Santiago Maza1, Diego Morata1, Miguel Angel Parada1, Marcela Pizarro1, Alberto Renzulli2, Marco Taussi2 and Eugenio E Veloso1,3, (1)University of Chile, Department of Geology and Andean Geothermal Center of Excellence (CEGA), Santiago, Chile, (2)Università degli Studi di Urbino Carlo Bo, Dipartimento di "Scienze Pure e Applicate" (DiSPeA), Urbino, Italy, (3)Pontifical Catholic University of Chile, Department of Structural Engineering and Geotechnics, Santiago, Chile
Abstract:
Recent (<26 Ma) Central Andean volcanism in northern Chile (17º40’-27º10’S) is mainly represented by eruption of large-scale stratovolcanoes. The Altiplano-Puna volcanic complex (APVC; 21°-24°S), a volcano-tectonic province within the Central Andes, is characterized by presence of both crystal-rich huge dacite-rhyolite ignimbrite sheets and domes (de Silva, 1989). The youngest activity of the APVC is the eruption of these domes, mostly occurred in the last 100 ka (Tierney et al., 2016).

Currently, a multidisciplinary work is in progress at the Central Andes, in northern Chile. This work is foccused on the main geothermal systems, especially on those distributed within the APVC. In particular, we obtained data from Pampa Apacheta area (near Chanka, Chac-Inka, and Cerro Pabellon domes), the San Pedro-Linzor NW-striking volcanic chain (including Chao Dacite and Chillahuita domes), El Tatio Geysers, and Cerro La Torta.

Extrusive products in the APVC show crustal isotopic signatures (87Sr/86Sr) increasing eastwards. Mafic enclaves of basic-intermediate composition are widespread within the dacitic domes of the APVC, as well as within the products on stratovolcanoes of this area. Geophysical surveys (e.g. magnetotelluric, teleseismic events, etc.), supported by thermobarometry of the erupted magmas, indicate a huge partially molten zone at upper crustal levels. These petrological and geophysical constraints clearly propose that the magmatic evolution of this volcano-tectonic province is associated with mixing between less evolved magmas and a partially molten mush (the Altiplano-Puna Magma Body; APMB) in the upper crust.

Our main goal is to integrate previous results with ongoing geochemical and isotopic data of fluids, surface and fluid temperature data, geological and structural mapping, melt inclusions analysis, and CO2 soil flux measurements. This multidisciplinary approach aims to improve the understanding of the origin, ascent and recharge processes of magmas at APMB, as well as the determination of eruption triggering mechanisms (e.g. magma mixing), and their relationship with the geothermal potential recognized throughout the APVC.

Ref: de Silva, 1989. Geology 17(12):1102-1106. Tierney et al., 2016. Geology 44(8):683-686.

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