Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits
Tara Djokic, Martin J. Van Kranendonk, Kathleen A. Campbell, Malcolm R. Walter & Colin R. Ward
Nature Communications 8, Article number: 15263 (2017)
doi: 10.1038/ncomms15263
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Microbiology Chemical origin of life Palaeontology Precambrian geology
Received: 18 July 2016 Accepted: 15 March 2017
Published online: 09 May 2017
Abstract
The ca. 3.48 Ga Dresser Formation, Pilbara Craton, Western Australia, is well known for hosting some of Earth’s earliest convincing evidence of life (stromatolites, fractionated sulfur/carbon isotopes, microfossils) within a dynamic, low-eruptive volcanic caldera affected by voluminous hydrothermal fluid circulation. However, missing from the caldera model were surface manifestations of the volcanic-hydrothermal system (hot springs, geysers) and their unequivocal link with life. Here we present new discoveries of hot spring deposits including geyserite, sinter terracettes and mineralized remnants of hot spring pools/vents, all of which preserve a suite of microbial biosignatures indicative of the earliest life on land. These include stromatolites, newly observed microbial palisade fabric and gas bubbles preserved in inferred mineralized, exopolymeric substance. These findings extend the known geological record of inhabited terrestrial hot springs on Earth by ∼3 billion years and offer an analogue in the search for potential fossil life in ancient Martian hot springs.
Acknowledgements
Many thanks to: J. Reinter for discussion and assistance with Raman spectroscopic data; C. Marjo for assistance with Raman spectroscopic data; K. Privat for assistance with SEM-EDS data and the electron microscope unit, UNSW. Research support provided by the Australian Centre for Astrobiology and School of Biological, Earth and Environmental Sciences at the University of New South Wales, the Sloan Foundation and the ARC Centre for excellence Core to Crust Fluid Systems. Phanerozoic hot spring comparative studies were supported by funding to K.A.C. from the New Zealand government (RSNZ Marsden Fund and Ministry of Business, Innovation and Employment) and the National Geographic Society. Gigapan image generated by Ken Williford and the abcLab, Jet Propulsion Laboratory, California Institute of Technology. Kind hospitality in the field was provided by Faye and Geoff Myers, and Haoma Mining.
Author information
Affiliations
Australian Centre for Astrobiology, PANGEA Research Centre and School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
Tara Djokic, Martin J. Van Kranendonk & Malcolm R. Walter
Australian Research Council Centre of Excellence for Core to Crust Fluid Systems (CCFS), Macquarie University, New South Wales 2109, Australia
Tara Djokic & Martin J. Van Kranendonk
Big Questions Institute, University of New South Wales Australia, Kensington, New South Wales, 2052 Australia
Martin J. Van Kranendonk
School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
Kathleen A. Campbell
School of Biological, Earth and Environmental Sciences, University of New South Wales Australia, Kensington, New South Wales 2052, Australia
Colin R. Ward
Contributions
The methodology was conceived and designed by T.D. and M.J.V.K. Geological mapping was carried out by T.D. and M.J.V.K. Petrographic analyses were carried out by T.D., M.J.V.K., K.A.C. and M.R.W. SEM-EDS data were acquired and interpreted by T.D. and M.J.V.K. XRD analysis spectra were acquired by C.R.W. All authors contributed to discussion, interpretation and writing.
Competing interests
The authors declare no competing financial interests.
Corresponding author
Correspondence to Tara Djokic.
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