Mineralizations and transition metal mobility driven by organic carbon during low-temperature serpentinization

Abstract Serpentinization is known to provide substantial amounts of energy in the form of molecular hydrogen along with a suite of abiotic organic compounds of low molecular weight (mainly as short chain alkanes and carboxylic acids), all sustaining the development of microbial ecosystems in the mantle-derived crust. The latter have a cryptoendolithic life style and are responsible for (i) the local formation of biomass and of organic metabolic byproducts and (ii) the production of extracellular polymeric substances which organize the community in the form of a biofilm at the surface of the rock-forming minerals. In accordance, whatever their origin, organic compounds can be diverse and widespread in the shallow oceanic crust where they undergo hydrothermal degradation and remobilization through fluid circulations. Here we show that organic carbon is directly involved in low temperature serpentinization reactions (