I am a scientist in my third year as a postdoctoral associate at Yale University. I am driven by curiosity about the interactions between planet Earth and its living biosphere over billions of years. In particular, my research explores how geological materials (rocks, minerals and sediments) select, shape and sustain communities of organisms, and how these communities in turn produce, degrade and modify rocky substrates to leave lasting traces in the geological record. The study of these interactions (“geobiology”) deepens our understanding of where we come from and improves our ability to search for life elsewhere in the universe. Much of my work has focused on the habitability of Mars, but I am also interested in the habitability of Earth’s deep subsurface. A second focus in recent years has been experimental palaeontology: the attempt to understand and replicate the processes that allow fossils to form.
Refereed journal articles
1. McMahon, S., Hood, A. v S., & McIlroy, D. The Origin and Occurrence of Subaqueous Sedimentary Cracks. Geological Society of London, Special Publications. In press.
2. McMahon, S., Anderson, R. P. A., Saupe, E. E., & Briggs, D. E. G. (2016). Experimental evidence for inhibition of bacterial growth by clay minerals and its implications for fossil preservation. Geology. In press. DOI:10.1130/G38454.1
3. McMahon, S., Parnell, J., & Blamey, N. J. (2016) Evidence for seismogenic hydrogen gas, a potential microbial energy source on Earth and Mars. Astrobiology. In press.
4. McCoy, V. E., Saupe, E. E., Lamsdell, J. C., Tarhan, L. G., McMahon, S., Lidgard, S., Mayer, P., Whalen, C. D., Soriano, C., Finney, L., Vogt, S., Clark, E. G., Anderson, R. O., Petermann, H., Locatelli, E. R., & Briggs, D. E. G. (2016) The Tully Monster is a Vertebrate. Nature 532, 496–499.
5. Neubeck, A., Tulej, M., Ivarsson, M., Broman, C., Riedo, A., McMahon, S., Wurz, P., & Bengston, S. (2016) Mineralogical determination in situ of a highly heterogeneous material using a miniaturized laser ablation mass spectrometer with high spatial resolution. International Journal of Astrobiology 15, 133–146.
6. Briggs, D.E.G., & McMahon, S. (2016) The role of experiments in investigating the taphonomy of exceptional preservation. Palaeontology 59, 1–11.
7. Parnell, J., McMahon, S. (2016) Physical and Chemical Controls on Habitats for Life in the Deep Subsurface Beneath Continents and Ice. Transactions of the Royal Society of London A 374, 20140293.
8. McMahon, S., Cockell, C. S. (2015) Martin Brasier (1947-2014): Astrobiologist. International Journal of Astrobiology 14, 527–531.
9. Blamey, N., Parnell, J., McMahon, S., Mark, D., Tomksinson, T., Lee, M., Shivak, J., Izawa, M., Banerjee, N., & Flemming, R. (2015) Evidence for methane in martian meteorites. Nature Communications 6: 7399.
10. Parnell, J., McMahon, S., Blamey, N. J. F., Hutchinson, I. B., Harris, L. V., Ingley, R., Edwards, H. G. M., Lynch, E. & Feely, M. (2014) Detection of reduced carbon in a basalt analogue for martian nakhlite: a signpost to a habitat on Mars. International Journal of Astrobiology. In press (early view online).
11. Price, M., Ramkissoon, N., McMahon, S., Miljkovic, K., Parnell, J., Wozniakiewicz, P., Kearsley, A., Blamey, N., Cole, M., & Burchell, M. (2014) Limits on methane release and generation via hypervelocity impact of Martian analog materials. International Journal of Astrobiology. In press (early view online).
12. McMahon, S., Parnell, J. (2014) Weighing the deep continental biosphere. FEMS Microbiology Ecology 87: 113-120. Chief Editor’s Choice, January 2014.
13. McMahon, S., O’Malley-James, J., & Parnell, J. (2013) Circumstellar habitable zones for terrestrial deep biospheres. Planetary and Space Science 85, 312–318.
14. McMahon, S., Parnell, J., Ponicka, J., Hole, M., & Boyce, A. (2013) The habitability of vesicles in martian basalt. Astronomy & Geophysics 54, 1.17–1.21.
15. Brasier, M., Matthewman, R., McMahon, S., Kilburn, M., & Wacey, D. (2013) Pumice from the ~3,460 Ma Apex Basalt, Western Australia: a natural laboratory for the early biosphere. Precambrian Research 224, 1–10.
16. McMahon, S., Parnell, J., & Blamey, N. J. F. (2013) Sampling methane in basalt on Earth and Mars. International Journal of Astrobiology 12, 113-122.
17. McMahon, S., Parnell, J., & Blamey, N. J. F. (2012). Sampling methane in hydrothermal minerals on Earth and Mars. International Journal of Astrobiology 11, 163-167.
18. Brasier, M.D., Matthewman, R., McMahon, S., & Wacey, D. (2011). Pumice as a Remarkable Substrate for the Origin of Life. Astrobiology 11, 725-735.
Conference proceedings (extended abstracts)
(Poster) McMahon, S. & Parnell, J. (2013) Potential for deep hydrogenotrophic life on Mars. In Proc. Lunar and Planetary Science Conf. XLIV, abstract 2870.
(Poster) McMahon, S., James, J. O., Parnell, J. (2013) Circumstellar habitable zones for deep biospheres. In Proc. Lunar and Planetary Science Conf. XLIV, abstract 2931.
(Poster) Price, M. C., Parnell, J., Wozniakiewicz, P. J., Kearsley, A. T., McMahon, S, Blamey, N. J. F. and M. J. Burchell, M. J. (2013) Gas retention in basaltic rocks following hypervelocity impact: implications for methane on Mars. In Proc. Lunar and Planetary Science Conf. XLIV, abstract 1935.
(Presented) McMahon, S. (2012).Plenary talk: Deep biospheres on Earth, Mars and beyond. ESA/ISGP Joint Life Sciences Meeting 2012, Aberdeen, UK [awaiting online release].
McMahon, S., Parnell, J. & Blamey, N. J. F. (2012). Analysis of volatile fluids in basalt: a possible source of Martian methane. In Proc. Lunar and Planetary Science Conf. XLIII, abstract 1046.
McMahon, S., Parnell, J., Burchell, M. & Blamey, N. J. F. (2012). Methane retention by rocks following simulated meteorite impacts: implications for Mars. In Proc. Lunar and Planetary Science Conf. XLIII, abstract 1040.
Other conference participation
(2016) Northeast Geobiology Meeting, Harvard University, MA, USA (Poster)
(2015) Palaeotological Association Annual Meeting, Cardiff, UK (Talk)
(2015) Northeast Geobiology Meeting, Princeton University, NJ, USA (Poster)
(2013) UK Astrobiology Conference (ASB5), Edinburgh, UK (Poster)
(2012) European Astrobiology Network Association Workshop, Stockholm, Sweden (Two talks)
(2012) Astrobiology Science Conference, Atlanta, Georgia, USA (Talk)
(2011) Royal Astronomical Society Specialist Discussion Meeting, London, UK (Talk)
Honours and awards
(2013, NASA Ames Research Centre) Planetary Biology Internship
(2013, University of Aberdeen) Principal’s Prize for Public Engagement with Research: Recognition of Special Achievement
(2009, University of Oxford) Palaeontological Association Prize
Awarded for best examination performance in Oxford cohort
(2009, Summer) E. P. Abraham Internship
Oxford University Museum of Natural History (palaeontology collections)
(2008, University of Oxford) Nuffield Undergraduate Research Bursary
Awarded for technical photography of putative early animal fossils
(2016 -) Council for the Defence of British Universities
(2014 -) International Journal of Astrobiology, Editorial Board
(2013 –) Astrobiology Society of Britain
(2012 –) Royal Astronomical Society