In-situ abiogenic methane synthesis from diamond and graphite under geologically relevant conditions

Miriam Pena Alvarez, Alberto Vitale Brovarone, Mary-Ellen Donnelly, Mengnan Wang, Philip Dalladay-Simpson, Ross Howie, Eugene Gregoryanz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Diamond and graphite are fundamental sources of carbon in the upper mantle, and their reactivity with H2-rich fluids present at these depths may represent the key to unravelling deep abiotic hydrocarbon formation. We demonstrate an unexpected high reactivity between carbons’ most common allotropes, diamond and graphite, with hydrogen at conditions comparable with those in the Earth’s upper mantle along subduction zone thermal gradients. Between 0.5-3 GPa and at temperatures as low as 300 °C, carbon reacts readily with H2 yielding methane (CH4), whilst at higher temperatures (500 °C and above), additional light hydrocarbons such as ethane (C2H6) emerge. These results suggest that the interaction between deep H2-rich fluids and reduced carbon minerals may be an efficient mechanism for producing abiotic hydrocarbons at the upper mantle.
Original languageEnglish
Article number6387
Pages (from-to)1-5
Number of pages5
JournalNature Communications
Volume12
DOIs
Publication statusPublished - 4 Nov 2021

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