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Detailed geochemical study of diffuse degassing in Puerto Naos, La Palma (Canary Islands) for geothermal exploration purposes

Gladys V. Melián1,2, Nemesio M. Pérez1,2, Daniela Taño Ramos1, Laura Trujillo Vargas1, Claudia Ramos Delgado1, Ana Gironés1,2, Sttefany Cartaya1,2, Mónica Arencibia1,2, María Asensio-Ramos1,  Eleazar Padrón1,2, Pedro A. Hernández1,2

  • Affiliations: 1Instituto Volcanológico de Canarias (INVOLCAN), Puerto de la Cruz, Tenerife, Canary Islands, Spain. 2Instituto Tecnológico y de Energías Renovables (ITER), Granadilla de Abona, Tenerife, Canary Islands, Spain. 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 14

  • Programme No: 5.1.20

  • Theme 5 > Session 1

Abstract

Sustainable exploitation of geothermal resources requires a thorough understanding of the chemical properties of geothermal fluids (water and gases) and the rocks that host their flow paths. Geochemical studies are fundamental to geothermal exploration and development as they provide critical information on the composition, origin and interactions of subsurface fluids and rocks. This information allows the identification of possible geothermal reservoirs, even in the absence of surface manifestations, as was the case in La Palma, Canary Islands until the 2021 eruption. Here are shown the results of an extensive soil gas survey (~5,000 sampling points/km²) conducted over a 0.11 km² area in Puerto Naos, western flank of Cumbre Vieja, La Palma. This area lacks of geothermal surface manifestations. 561 sampling points were selected to measure in situ diffuse CO₂ efflux and ²²²Rn gas activity. In addition, gas samples from soil atmosphere were collected at a depth of 40 cm for subsequent chemical and isotopic (δ13C-CO2) analysis. Statistical and spatial analysis of the data reveals significant anomalies indicating gas enrichment from deeper sources. These anomalies may be related to zones of higher vertical permeability and possible potential upwelling or boiling regions at greater depth. The results underscore the relevance of surface gas geochemical studies to delineate subsurface permeability and geothermal potential in areas without surface manifestations, providing valuable data for targeted geothermal exploration and sustainable energy development.