2021/06/03 by Henrik Drake, Nick M.W. Roberts, Manuel Reinhardt +5 · 1 citation
Earth and Planetary Sciences · Environmental Science · #Paleontology and Stratigraphy of Fossils #Methane Hydrates and Related Phenomena #Geology and Paleoclimatology Research
paper · pdf · doi:10.1038/s43247-021-00170-2
openalex publication_date 2021/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Abstract Earth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.