Quantification of Methanogenic Pathways Using Stable Carbon Isotopic Signatures

2019 ◽  
pp. 89-94
Author(s):  
Quan Yuan
Keyword(s):  
Stable Carbon ◽  
Isotopic Signatures ◽  
Carbon Isotopic

scholarly journals Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Henrik Drake ◽  
Nick M. W. Roberts ◽  
Manuel Reinhardt ◽  
Martin Whitehouse ◽  
Magnus Ivarsson ◽  
...  
Keyword(s):  
Fennoscandian Shield ◽  
Stable Carbon ◽  
Deep Biosphere ◽  
Isotopic Signatures ◽  
Microbial Life ◽  
Carbon Isotopic ◽  
Terrestrial Life ◽  
Vein Mineral ◽  
Methyl Branched Fatty Acids

AbstractEarth’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.

Source identification of PAHs in soils based on stable carbon isotopic signatures

2018 ◽  
Vol 48 (13-15) ◽  
pp. 923-948 ◽  
Author(s):  
Peng Gao ◽  
Hongbo Li ◽  
Chris P. Wilson ◽  
Timothy G. Townsend ◽  
Ping Xiang ◽  
...  
Keyword(s):  
Source Identification ◽  
Stable Carbon ◽  
Isotopic Signatures ◽  
Carbon Isotopic

scholarly journals Isotopic Signatures of Carbon in the ‘Los Pobres’ Graphite Mine, Ronda, Spain

2020 ◽  
Vol 61 (4) ◽  
Author(s):  
Anna Neubeck ◽  
Curt Broman ◽  
Magnus Ivarsson ◽  
Nils G Holm ◽  
Martin Whitehouse ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Host Rock ◽  
Stable Carbon Isotopes ◽  
Stable Carbon ◽  
Isotopic Signatures ◽  
The Third ◽  
Carbon Isotopic ◽  
Isotopic Measurements ◽  
Crystalline Graphite

Abstract Graphite formation temperatures in the ‘Los Pobres’ mine within the Ronda peridotite, Spain, previously reported to be between 770 and 820 °C, have been reinterpreted based on new temperature measurements using Raman spectroscopy. Additional in situ and bulk stable carbon isotopic measurements and fluid inclusion studies contributed to improved understanding of parts of the graphite formation process. Raman spectroscopy revealed that the formation of the ‘Los Pobres’ graphite extends to temperatures as low as 500 °C, indicating a broader temperature range than previously reported. Stable carbon isotopes and temperature estimates suggest two different crystallization events, followed by a late hydrothermal alteration of the host rock. The first event occurred at temperatures higher than ∼600°C, in which crystalline graphite was formed with a mixed 13C composition as a result of the mixing of two different carbon-bearing sources. The second graphite formation event took place below ∼600°C, within the same system, but with lower purity and crystallinity of the graphite. In the third event, the temperature decreased to less than 550 °C, and hydrothermal fluids altered the host rock, precipitating silica and iron oxides in veins penetrating both the host rock and the deposited graphite.

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