# Exploring for natural hydrogen in peralkaline nepheline-syenite plutons: the Kola peninsula, NW Russia

Camille Dusséaux, Vyacheslav Pukha, Olga Mokrushina, Andrey Kalashnikov, Jessy Dominique, Loïs Monnier, Stefano Salvi, Frédéric Donzé, Laurent Truche, Valentin Nivin, et al.

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## To cite this version:

Camille Dusséaux, Vyacheslav Pukha, Olga Mokrushina, Andrey Kalashnikov, Jessy Dominique, et al.. Exploring for natural hydrogen in peralkaline nepheline-syenite plutons: the Kola peninsula, NW Russia. Goldschmidt2022, 2022, Honolulu, United States. 10.46427/gold2022.10129. hal-04251615

HAL Id: hal-04251615

https://hal.science/hal-04251615v1

Submitted on 20 Oct 2023

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# Exploring for natural hydrogen in peralkaline nepheline-syenite plutons: the Kola peninsula, NW Russia

Camille Dusséaux<sup>*1</sup>, Vyacheslav Pukha<sup>2</sup>, Olga Goychuk<sup>2</sup>, Andrey Kalashnikov<sup>2</sup>, Jessy Dominique<sup>1</sup>, Loïs Monnier<sup>3</sup>, Stefano Salvi<sup>3</sup>, Frédéric-Victor Donzé<sup>1</sup>, Laurent Truche<sup>1</sup>, Valentin Nivin<sup>2</sup>, Julia Mikhailova<sup>2</sup>

It is well established that serpentinization of ultramafic rocks produces natural hydrogen, a phenomenon extensively investigated at seafloor and continents seepage sites. Much less is known that remarkable amounts of hydrogen are detected in peralkaline plutons (e.g. Ilímaussaq, Greenland; Strange Lake, Canada; Khibiny and Lovozero, Russia). The most spectacular occurrences are the last two - the world's largest alkalic intrusions - where up to 40 mol % H₂, along with CH₄ and other gases have been detected in fluid inclusions<fnref n="1" /> and found to migrate freely in fractures and mine workings<fnref n="2" />. Previous studies have documented extremely uneven distribution of both occluded and, especially, free gases (mainly CH₄ and H₂)<fnref n="2" />,<fnref n="4" />,<fnref n="5" />. These authors consider that these gases formed abiogenically, either through magmatic processes or during subsolidus hydrothermal alteration. Relatively elevated concentrations of subsurface H₂ are found in loose sediments near lithological boundaries, e.g. in fenitized Archean gneiss surrounding both Paleozoic plutons, at the contact between layered and epidalyte-rich units in Lovozero, and in the Central Arch in Khibiny, where occur large REE and phosphate deposits.

Our team seeks to understand how and when hydrogen and associated gases were produced, their migration pathways and where they are stored in Khibiny-Lovozero. To constrain these processes, our efforts combine geochemical, geophysical, mineralogical and environmental approaches. Thus far, field investigations include: (1) mapping soil gases using multi-gas detectors; (2) collecting different rock samples from outcrops and boreholes; (3) sampling spring water and soils. Complementary laboratory analyses include: (1) detailed petrology of rock samples (SEM-EDS, microprobe); (2) bulk-rock gas chromatography, using mechanical grinding; (3) microthermometry and Raman investigation of fluid and melt inclusions. We also experimentally simulated the hydrothermal alteration of pure epidalyte and rocks containing epidalyte and arfvedsonite (250°C, 2 months) to assess their capacity to produce hydrogen and to discuss H₂-producing reactions<fnref n="3" />.

The study of the origin, migration and storage of natural hydrogen in peralkaline rocks will provide a better understanding of H₂ production during the formation of ore deposits and its role in environmental disturbances. It is also essential for an adequate assessment of natural H₂ as a potential energy resource from continental sources.

**Keywords**: hydrogen, exploration, water-rock interaction; alkalic; kola; fluid inclusions; melt inclusions

<footnote><sup>*1</sup> Université Grenoble Alpes, ISTERRE, CNRS, F-38058, Grenoble, France</footnote>

<footnote><sup>*2</sup> Geological Institute, Kola Science Centre, Russian Academy of Sciences, 184209 Apatity, Russia</footnote>

<footnote><sup>*3</sup> Géosciences Environnement Toulouse, University of Toulouse, CNES, CNRS, IRD, UPS, 31400 Toulouse, France</footnote>

<footnote n="1">1. Potter, J., Salvi, S. & Longstaffe, F. J. Abiogenic hydrocarbon isotopic signatures in granitic rocks: Identifying pathways of formation. *Lithos* **182–183**, 114–124 (2013).</footnote>

<footnote n="2">2. Nivin, V. A. Occurrence Forms, Composition, Distribution, Origin and Potential Hazard of Natural Hydrogen–Hydrocarbon Gases in Ore Deposits of the Khibiny and Lovozero Massifs: A Review. *Minerals* **9**, 535 (2019).</footnote>

<footnote n="3">3. Truche, L. et al. Hydrogen generation during hydrothermal alteration of peralkaline granite. *Geochim. Cosmochim. Acta* **308**, 42–59 (2021).</footnote>

<footnote n="4">4. Nivin, V. The Origin of Hydrocarbon Gases in the Lovozero Nepheline-Syenite Massif (Kola Peninsula, NW Russia), as Revealed from He and Ar Isotope Evidence. *Minerals* **10**, 830 (2020).</footnote>

<footnote n="5">5. Nivin, V. A., Treloar, P. J., Konopleva, N. G. & Ikorsky, S. V. A review of the occurrence, form and origin of C-bearing species in the Khibiny Alkaline Igneous Complex, Kola Peninsula, NW Russia. *Lithos* **85**, 93–112 (2005).</footnote>