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Trace metals in hydrothermal systems: Northern Volcanic Zone, Iceland

Júlia Mattioli 1, Kim Berlo2, Daniele Luigi Pinti1 ,Vincent van Hinsberg2, Ásgerður K. Sigurðardóttir3, Helgi Arnar Alfreðsson3, Bjarni Gautason4

  • Affiliations: 1Geotop & Département des sciences de la Terre et de l\'atmosphère, Université du Québec à Montréal, CP.8888 Succ. Centre Ville, H3C 3P8 Montréal, Canada; 2Geotop & Earth and Planetary Sciences Department, McGill University, 3450, University Street, Montréal, Canada; 3Landsvirkjun, Háaleitisbraut 68, Reykjavik, Iceland; 4ÍSOR Iceland GeoSurvey, Rangárvellir 2, Akureyri, Iceland 

  • Presentation type: Poster

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

  • Poster Board Number: 43

  • Programme No: 3.8.27

  • Theme 3 > Session 8

Abstract

High-enthalpy hydrothermal fluids are an important source of clean energy for the green transition. Apart from heat, they also transport volatile elements from the deep Earth to the surface, contributing to element cycling between the lithosphere and the atmosphere. Hydrothermal fluid composition is the result of multiple processes and sources. In particular, the processes of magmatic degassing and fluid-rock interactions contribute to the trace-element load of these fluids, while meteoric water dilutes them. In previous work from our group, we combined trace metal signatures in down-well and surface geothermal fluids with fresh and altered reservoir host rock compositions to estimate the relative contributions of magmatic outgassing and fluid-rock interactions to the trace-metal budget of deep fluids in the Northern Volcanic Zone of Iceland. The surface fluids are depleted in base metals compared to deep-sampled fluids indicating a need to understand the sources and sinks of metals in hydrothermal fluids to interpret surface fluid compositions. Our data comprises stable water isotopes (δ¹⁸O, δ²H), Sr isotopes (87Sr/86Sr), noble gas isotopes (He, Ne, Ar, Kr, Xe) and trace metal analyses of wells in the Krafla, Bjarnarflag and Þeistareykir geothermal stations of the NVZ. Using correlations between isotopes and trace elements combined with geochemical modelling, we identify multiple sources of fluids, correcting for processes such as boiling and scale precipitation that alter the deep fluid composition, and providing insights on the sources of metals in these deep crustal fluids.