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RESEARCH PRODUCT

Carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at Copahue-Caviahue Volcanic Complex (Argentina)

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Fil: Chiodini, Giovanni. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna. Bologna, Italia. Fil: Cardellini, Carlo. Università degli Studi di Perugia, Dipartimento di Fisica e Geologia. Perugia, Italy. Fil: Lamberti, María C. Universidad de Buenos Aires. Instituto de Estudios Andinos. Buenos Aires, Argentina. Fil: Agusto, Mariano. Universidad de Buenos Aires. Instituto de Estudios Andinos. Buenos Aires, Argentina. Fil: Caselli, Alberto Tomás Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro. Argentina. Fil: Liccioli, Caterina. Universidad de Buenos Aires. Instituto de Estudios Andinos. Buenos Aires, Argentina. Fil: Tamburello, G.. Università degli Studi di Palermo. Italia. Fil: Tassi, Franco. Università degli Studi di Firenze, Dipartimento di Scienze della Terra, Istituto di Geoscience e Georisorse–Consiglio Nazionale delle Ricerche. Florencia, Italia. Fil: Vaselli, O. Department of Earth Sciences, University of Florence, Institute of Geosciences and Earth Resources of the National Research Council. Florencia, Italia. Fil: Caliro, Stefano. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli-Osservatorio Vesuviano. Napoli, Italia. The north-western sector of Caviahue caldera (Argentina), close to the active volcanic system of Copahue, is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that ~165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H–C–O gas system indicate the presence of a large, probably unique, single phase vapor zone at 200–210 °C feeding the hydrothermal manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural ther-mal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera. The north-western sector of Caviahue caldera (Argentina), close to the active volcanic system of Copahue, is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that ~165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H–C–O gas system indicate the presence of a large, probably unique, single phase vapor zone at 200–210 °C feeding the hydrothermal manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural ther-mal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera.