CARBON DIOXIDE DIFFUSE DEGASSING AND THERMAL ENERGY RELEASE AT CERRO BLANCO VOLCANIC – HYDROTHERMAL AREA, SOUTHERN PUNA (NW ARGENTINA)

MASSENZIO, A.; LAMBERTI, M.C.; AGOSTINA CHIODI; AGUSTO, M.; WALTER BAEZ; JOSÉ VIRAMONTE

Workshop; 14th Field Workshop on Volcanic Gases; 2022

This work presents the first carbon dioxide diffuse degassing survey in the Cerro Blanco geothermal system, located in the south of the Puna region, Northwest Argentina. Due to the large extension of the study area, the survey was developed at two different scales of analysis. Measurements of soil CO2 flux and temperature were collected along two segments that crosscut the Cerro Blanco caldera and Los Hornitos thermal site. Significant soil diffuse anomalies were only found at a hydrothermal site in the center on the Cerro Blanco caldera, namely, CBa, where 135 soil CO2 flux and temperature measurements were collected. The measured CO2 fluxes were elaborated using statistical and geostatistical methods, in order to investigate the origin of the CO2 diffuse emission, map the spatial distribution, quantify the amount of CO2 daily released from the surveyed surface and quantify the thermal energy involved in the diffuse degassing process. The CBa hydrothermal site consists of a restricted area characterized by the presence of steam-dominated fumaroles, where CO2 soil degassing produced a relatively narrow range of CO2 flux values, being comprised between 320 g m-2 d-1. The data from CBa area can be modeled by combining two log-normal populations, namely A and B. Population A represents the high flux population and population B is characterized by a CO2 flux two orders of magnitude lower than that of A, and it represents 88% of the dataset. The SGS-computed CO2 release is 187 kg d-1. The associated thermal energy is 20.57 kJ/s.