author={Giuseppe Etiope and Barbara Sherwood Lollar},
  journal={Reviews of Geophysics},
  pages={276 - 299}
Over the last 30 years, geochemical research has demonstrated that abiotic methane (CH4), formed by chemical reactions which do not directly involve organic matter, occurs on Earth in several specific geologic environments. It can be produced by either high‐temperature magmatic processes in volcanic and geothermal areas, or via low‐temperature (<100°C) gas‐water‐rock reactions in continental settings, even at shallow depths. The isotopic composition of C and H is a first step in distinguishing… 
Seepage in Serpentinised Peridotites and on Mars
This book has mainly addressed the classical seepage of natural gas of biotic (microbial and thermogenic) origin in sedimentary rocks. It is also known that methane and other light hydrocarbons can
Validity of geochemical signatures of abiotic hydrocarbon gases on Earth
Abiotic synthesis has been hypothesized as a mechanism for occurrences of hydrocarbon gases with atypical molecular and isotopic compositions. This paper provides biotic interpretations of these
The origin, source, and cycling of methane in deep crystalline rock biosphere
The origin, source, and cycling of methane in deep terrestrial crystalline bedrock with an emphasis on microbiology is reviewed and, based on their preferred carbon metabolism, methanogenic microbes appeared to have similar spatial distribution among the different sites.
The Production of Methane, Hydrogen, and Organic Compounds in Ultramafic-Hosted Hydrothermal Vents of the Mid-Atlantic Ridge
Abstract Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge.


Multiple origins of methane in the Earth
Natural emissions of methane from geothermal and volcanic sources in Europe
Abiogenic formation of alkanes in the Earth's crust as a minor source for global hydrocarbon reservoirs
The progressive isotopic trends for the series of C1–C4 alkanes indicate that hydrocarbon formation occurs by way of polymerization of methane precursors, and it can now be rule out the presence of a globally significant abiogenic source of hydrocarbons.
Laboratory Simulations of Abiotic Hydrocarbon Formation in Earth’s Deep Subsurface
In recent years, methane and other light hydrocarbons with an apparently abiotic origin have been identified in an increasing number of geologic fluids on Earth. These compounds have been found in a
Implications of present‐day abiogenic methane fluxes for the early Archean atmosphere
During Earth's early history, greenhouse warming by atmospheric methane helped to maintain elevated surface temperatures. Here, we estimate the present‐day abiogenic CH4 flux generated by mineral
Reappraisal of the fossil methane budget and related emission from geologic sources
Converging evidence from new top‐down and bottom‐up estimates of fossil “radiocarbon‐free” methane emissions indicates that natural geologic sources account for a substantial component of the