Soil and fumarole gas emissions at Deception Island volcano, Antarctica: prospecting for its potential thermal energy

GUERRIERO, L.; LAMBERTI, M.C.; MASSENZIO, A.; NUÑEZ, N.; FORTE, P.; AGUSTO, M.

Arequipa

Workshop; 14th Field Workshop on Volcanic Gases; 2022

Commission on the Chemistry on Volcanic Gases

Deception Island (62°43´S, 60°57´W) is an active volcano located at the southwestern sector of the South Shetland Islands (Antarctica), within the Bransfield Strait, and whose last eruptions took place in 1967-1970. The volcanic edifice emerges from the sea floor forming a horseshoe-shaped island. The island hosts several hydrothermal sites, which are characterized by steaming grounds and/or fumarolic emissions.From January-March 2022, an extensive geochemical campaign was carried out in seven hydrothermal sites. In this work, we report the results of a carbon dioxide (CO2) soil diffuse degassing survey and direct fumarole sampling. CO2 soil diffuse degassing was studied acquiring 857 CO2 soil diffuse flux and 1011 soil temperature measurements. Soil CO2 fluxes were obtained by means of a West Systems portable flow-meter. In addition, fumaroles were studied taking 40 samples with an alkaline trap (NaOH - Cd(OH)2) in 10 subaerial and submerged gas discharges.Measurements of CO2 soil diffuse flux showed values up to ⁓13400 g m-2d-1. Soil temperatures ranged between -3 and ⁓50°C, whereas fumaroles reached temperatures as high as 90-100°C. Most hydrothermal sites present well defined diffuse degassing structures that release up to 5 t d-1 of volcanic CO2 into the atmosphere. Primero de Mayo bay constitutes the largest fumarolic field in the island, with gas emissions characterized by CO2 and H2S, with minor proportions of SO2.A full analysis of geochemical and isotopic dataset will allow identifying the different sources of the gas emissions, estimating the total output of CO2 and calculating the thermal energy release of Deception Island.