Alteration of ultramafic rocks plays a major role in the production of hydrocarbons and organic compounds via abiotic processes on Earth and beyond and contributes to the redistribution of C between solid and fluid reservoirs over geological cycles. Abiotic methanogenesis in ultramafic rocks is well documented at shallow conditions, whereas natural evidence at greater depths is scarce. Here we provide evidence for intense high-pressure abiotic methanogenesis by reduction of subducted ophicarbonates. Protracted (Z0.5–1Ma), probably episodic infiltration of reduced fluids in the ophicarbonates and methanogenesis occurred from at least B40km depth to B15–20km depth. Textural, petrological and isotopic data indicate that methane reached saturation triggering the precipitation of graphitic C accompanied by dissolution of the precursor antigorite. Continuous infiltration of external reducing fluids caused additional methane production by interaction with the newly formed graphite. Alteration of high-pressure carbonate-bearing ultramafic rocks may represent an important source of abiotic methane, with strong implications for the mobility of deep C reservoirs.

Alberto Vitale Brovarone, Isabelle Martinez, Agnès Elmaleh, Roberto Compagnoni, Carine Chaduteau, Cristiano Ferraris, et al. (2017). Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps. NATURE COMMUNICATIONS, 8, 1-13 [10.1038/ncomms14134].

Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps

Alberto Vitale Brovarone;
2017

Abstract

Alteration of ultramafic rocks plays a major role in the production of hydrocarbons and organic compounds via abiotic processes on Earth and beyond and contributes to the redistribution of C between solid and fluid reservoirs over geological cycles. Abiotic methanogenesis in ultramafic rocks is well documented at shallow conditions, whereas natural evidence at greater depths is scarce. Here we provide evidence for intense high-pressure abiotic methanogenesis by reduction of subducted ophicarbonates. Protracted (Z0.5–1Ma), probably episodic infiltration of reduced fluids in the ophicarbonates and methanogenesis occurred from at least B40km depth to B15–20km depth. Textural, petrological and isotopic data indicate that methane reached saturation triggering the precipitation of graphitic C accompanied by dissolution of the precursor antigorite. Continuous infiltration of external reducing fluids caused additional methane production by interaction with the newly formed graphite. Alteration of high-pressure carbonate-bearing ultramafic rocks may represent an important source of abiotic methane, with strong implications for the mobility of deep C reservoirs.
2017
Alberto Vitale Brovarone, Isabelle Martinez, Agnès Elmaleh, Roberto Compagnoni, Carine Chaduteau, Cristiano Ferraris, et al. (2017). Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps. NATURE COMMUNICATIONS, 8, 1-13 [10.1038/ncomms14134].
Alberto Vitale Brovarone; Isabelle Martinez; Agnès Elmaleh; Roberto Compagnoni; Carine Chaduteau; Cristiano Ferraris; Imène Esteve...espandi
File in questo prodotto:
File Dimensione Formato  
Vitale Brovarone et al 2017 NatComm.pdf

accesso aperto

Tipo: Versione (PDF) editoriale
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 5.74 MB
Formato Adobe PDF
5.74 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/827234
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 124
  • ???jsp.display-item.citation.isi??? 116
social impact