Fate of hydrocarbons in iron-bearing mineral environments during subduction

Aleksandr Serovaiskii, Elena Mukhina, Leonid Dubrovinsky, Aleksey Chernoutsan, Daniil Kudryavtsev, Catherine McCammon, Georgios Aprilis, Ilya Kupenko, Aleksandr Chumakov, Michael Hanfland, Vladimir Kutcherov

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)

    Abstract

    Subducted sediments play a key role in the evolution of the continental crust and upper mantle. As part of the deep carbon cycle, hydrocarbons are accumulated in sediments of subduction zones and could eventually be transported with the slab below the crust, thus affecting processes in the deep Earth’s interior. However, the behavior of hydrocarbons during subduction is poorly understood. We experimentally investigated the chemical interaction of model hydrocarbon mixtures or natural oil with ferrous iron-bearing silicates and oxides (representing possible rock-forming materials) at pressure-temperature conditions of the Earth’s lower crust and upper mantle (up to 2000(±100) K and 10(±0.2) GPa), and characterized the run products using Raman and Mössbauer spectroscopies and X-ray diffraction. Our results demonstrate that complex hydrocarbons are stable on their own at thermobaric conditions corresponding to depths exceeding 50 km. We also found that chemical reactions between hydrocarbons and ferrous iron-bearing rocks during slab subduction lead to the formation of iron hydride and iron carbide. Iron hydride with relatively low melting temperature may form a liquid with negative buoyancy that could transport reduced iron and hydrogen to greater depths.

    Original languageEnglish
    Article number651
    JournalMinerals
    Volume9
    Issue number11
    DOIs
    Publication statusPublished - Nov 2019

    Keywords

    • Hydrocarbons
    • Iron carbide
    • Iron hydride
    • Mantle
    • Petroleum
    • Subduction

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