EGU2020-9161
https://doi.org/10.5194/egusphere-egu2020-9161
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Volatile organic compounds in barite-hosted fluid inclusions from the 3.5 Ga old Dresser Formation, Western Australia

Volker Thiel, Jan-Peter Duda, Alfons M. van den Kerkhof, Joachim Reitner, and Helge Mißbach
Volker Thiel et al.
  • Geoscience Centre, University of Göttingen, Göttingen, Germany

The c. 3.5 Ga Dresser Formation of the East Pilbara Craton (Western Australia) contains large amounts of blackish barite. These rocks produce an intense sulfidic odor when crushed, resulting from abundant primary fluid inclusions. In part, the black barites are interbedded with sulfidic stromatolites. Using Raman spectroscopy, microthermometry, and two different online GC–MS approaches, we characterized in detail the chemical composition of the barite-hosted fluid inclusions. Our GC–MS techniques were based on (i) thermodecrepitation at 150-250°C and (ii) solid phase microextraction (SPME)–GC–MS at reduced temperature (50°C), thereby minimizing external contamination and artefact formation. Major fluid inclusion classes yielded mainly H2O, CO2, and H2S in varying abundance, along with minor amounts of COS and  CS2, N2, and CH4 (< 1%). Notably, we also detected a wide range of volatile organic compounds, including short–chain ketones and aldehydes, thiophenes, and various organic (poly)sulfides. Some of these compounds (CH3SH, acetic acid) have previously been invoked as initials agents for carbon fixation under primordial conditions, but up to now their presence had not been observed in Precambrian materials. Based on our findings, we hypothesize that hydrothermal seepage of organic and inorganic compounds during Dresser times provided both, catabolic and anabolic substrates for early microbial metabolisms.

How to cite: Thiel, V., Duda, J.-P., van den Kerkhof, A. M., Reitner, J., and Mißbach, H.: Volatile organic compounds in barite-hosted fluid inclusions from the 3.5 Ga old Dresser Formation, Western Australia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9161, https://doi.org/10.5194/egusphere-egu2020-9161, 2020

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