Abstract_EANA2025-17

Abstract EANA2025-17

Azorean Hydrothermal Systems as Geochemical Analogues to Putative Vents in the Icy Moons

Orench-Benvenutti, José M. (1); Ramos, Carlos (2); Brito de Gouveia, Lara (1); Carvalho, Madalena (1); Rodrigues, Paulo (1); Colaço, Ana (3); Silva, Catarina (4, 5); Viveiros, Fátima (4, 6) Cesário, Rute (1); Canário, João (1); Jordan, Seán F. (7); Martins, Zita (1)

(1) Centro de Química Estrutural, Institute of Molecular Sciences and Department of Chemical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal, (2) Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal, (3) Universidade dos Açores, Instituto de Investigação em Ciências do Mar - OKEANOS, Horta, Portugal, (4) IVAR–Instituto de Investigação em Vulcanologia e Avaliação de Riscos, Universidade dos Açores, Ponta Delgada, Portugal, (5) eCentro de Informação e Vigilância Sismovulcânica dos Açores (CIVISA), Ponta Delgada, Portugal, (6) Faculdade de Ciências e Tecnologia, Universidade dos Açores, Ponta Delgada, Portugal, (7) Life Sciences Institute, School of Chemical Sciences, Dublin City University, Dublin, Ireland

Hydrothermal vents are prime environments for origin-of-life studies. While the role of alkaline vents has been studied in prebiotic chemistry, mildly acidic to neutral (pH ~5–8) vents also generate energy gradients capable of supporting protocell formation [1,2]. These Earth-based systems serve as analogues for putative hydrothermal activity in the subsurface oceans of icy moons like Enceladus and Europa [3,4]. We sampled hydrothermal (6–8 m and 25–40 m) and fumarolic systems across the Azores archipelago, with sediment, liquid, and gas samples being analyzed. Sediments underwent sequential extraction and acid digestion, before trace element quantification by ICP-MS. Liquids were tested for Cl⁻, NO₃⁻, and SO₄²⁻ via ion exchange chromatography. Gas compositions were assessed through gas chromatography, potentiometric, and colorimetric titration. The data revealed trace elements such as As, Ba, Cd, Cr, Cu, Hg, Pb, U, and V across the seawater column. Biologically relevant elements like Mo, Se, and Sr were found in low concentrations across water and sediment samples. Cl⁻ and SO₄²⁻ levels in liquid samples were consistent with marine and freshwater systems, respectively, while nitrate was undetectable [5]. Gas analysis showed dominant H₂O and CO₂, mirroring Enceladus plumes [6]. Minor gases, including Ar, O₂, CH₄, He, H₂S, and N₂, match the emissions from active Azorean volcanoes [6–11]. Vent pH ranged from 6.9 to 8.0, fitting with modeled pH for Enceladus (7.9–12) and Europa (2.6–8.4) [10,12–15]. Although no uniform trend was observed in trace element profiles in liquid samples, Cl⁻ (~475 mM) and SO₄²⁻ (~23 mM) exceeded or overlapped estimates for Enceladus and Europa (Cl⁻: ~200–250 mM; SO₄²⁻: <1–40 mM). Our results support the Azorean hydrothermal systems as robust analogues for extraterrestrial environments in which putative life forms may exist [3,4,10–12,16–18].

Acknowledgements
Financial support from Fundação para a Ciência e a Tecnologia (FCT) is acknowledged by Z.M. (project ORIGINS, 2022.05284.PTDC), J.M.O.-B. (PhD fellowship 2024.01442.BD), and AC (CEECIND/00101/2021:https://doi.org/10.54499/2021.00101.CEECIND/CP1669/CT0001) through FCT, I.P., under projects UIDB/05634/2025 and UIDP/05634/2025.

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