Abiogenesis not required to explain the origin of volcanic-hydrothermal hydrocarbons

  • Abiotic formation of n-alkane hydrocarbons has been postulated to occur within Earth's crust. Apparent evidence was primarily based on uncommon carbon and hydrogen isotope distribution patterns that set methane and its higher chain homologues apart from biotic isotopic compositions associated with microbial production and closed system thermal degradation of organic matter. Here, we present the first global investigation of the carbon and hydrogen isotopic compositions of n-alkanes in volcanic-hydrothermal fluids hosted by basaltic, andesitic, trachytic and rhyolitic rocks. We show that the bulk isotopic compositions of these gases follow trends that are characteristic of high temperature, open system degradation of organic matter. In sediment-free systems, organic matter is supplied by surface waters (seawater, meteoric water) circulating through the reservoir rocks. Our data set strongly implies that thermal degradation of organic matter is able to satisfy isotopic criteria previously classified as being indicative of abiogenesis. Further considering the ubiquitous presence of surface waters in Earth’s crust, abiotic hydrocarbon occurrences might have been significantly overestimated.

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Author:Jens Fiebig, Andri Stefánsson, Andrea Ricci, Franco Tassi, Fatima Viveiros, Catarina Silva, Taryn Lopez, Christoph Schreiber, Sven Hofmann, Bruce W. Mountain
Parent Title (English):Geochemical perspectives letters
Place of publication:[Paris]
Contributor(s):Liane G. Benning
Document Type:Article
Year of Completion:2019
Date of first Publication:2019/07/29
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2019/09/30
Tag:abiogenesis; hydrocarbons; volcanic gases
Page Number:5
First Page:23
Last Page:27
Published by the European Association of Geochemistry under Creative Commons License CC BY-NC-ND 4.0
Institutes:Geowissenschaften / Geographie / Geowissenschaften
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
Open-Access-Publikationsfonds:Geowissenschaften / Geographie
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell - Keine Bearbeitung 4.0