Independent Researcher 

phone (617) 230 2860
email gizon’AT’

Department of Earth, Atmospheric and Planetary Sciences
Massachusetts Institute of Technology
E25-631, 45 Carleton Street
Cambridge, MA 02139



2023– Boyle/Ono Research Specialist (80:20), Independent Researcher, MIT, USA
2017–2023: Research Scientist and Acting Lab Manager, Summons Lab, MIT, USA.
2016–2017: Postdoctoral Associate, Light-Stable Isotope Geochemistry, MIT, USA.
2013–2016: Postdoctoral Research Associate, Light-Stable Isotope Geochemistry, St Andrews University, UK.
2013–2016: Visiting Research Associate, University of Leeds, UK.
2013–2016: Visiting Research Associate, University of Maryland, USA.
2008–2012: PhD, Trace Element and Isotope Geochemistry, The Open University, UK.
2007–2008: MSc, Geochemistry, The University of Leeds, UK.
2004–2007: BSc, Geological Sciences, The University of Leeds, UK.


I have very broad research interests having worked on a variety of events over varying timescales that encompass the majority of Earth’s history. In the broadest sense I am interested in the exploitation of elemental and isotopic proxies to answer a broad range of pertinent geological, palaeoceanographic and low-temperature geochemical questions. At the heart of my research is the desire to develop an understanding of the causes and consequences of transient aberrations in the Earth system (e.g. marine anoxia, climate change and mass extinctions), their effects on global biogeochemical cycles and the implications for the biosphere, both in the past and as a consequence of anthropogenic negligence.

More recently I have become increasingly fascinated with the quadruple sulphur-isotope record. The “mass-independency” of the S-isotope record has been used extensively since its discovery to chart the rise in atmospheric oxygen; however, if we consider its secular evolution, the route to its demise at the GOE is far from straightforward: displaying variable magnitude and changeable relationships between the minor S-isotopes (∆36S/∆33S). Understanding how to read this rich tapestry of information is central to answering key questions surrounding the evolution of the biosphere, its effect on planetary chemistry, and ultimately how our planet transitioned towards the habitable oxygenated planet we’re all familiar with today. All of which have ramifications for the search for life outside of our solar system.

In this vein, during my time at MIT I will be constructing high-resolution quadruple-S, nitrogen and carbon isotope records from newly cored continuous expressions of the Great Oxidization Event (GOE) obtained from the Transvaal Supergroup, South Africa. These data will provide unprecedented insight into the directionality, and timing of planetary oxygenation, whilst providing a robust framework for future research on the coevolution of Earth’s life and the surface environment.

Commercial Services: From time to time we conduct commercial isotopic and organic analyses. Analysis costs are strongly influenced by the amount of preparative effort expended and, naturally, reflect the sample and analysis type(s). Discounts are available for fully collaborative endeavours that align with our own research interests. If you are interested in any of the facilities we offer, or are interested in conducting work in the Summons Lab more generally, then please do not hesitate to reach out.

Select Publications

Google scholar citations

  • Rezeau, H., Jagoutz, O., Beaudry, P., Klein, B.Z., Izon, G., & Ono. S. Lower crustal assimilation revealed by sulfur isotope systematics of the Bear Valley Intrusive Suite, southern Sierra Nevada Batholith, California, USA. Contributions to Mineralogy and Petrology (Submitted; 2023).
  • Havsteen, J.C., Eickmann, B., Izon, G., Kleinhanns, I.C., Rosca, C., Beukes, N.J., Schoenberg, R. Atmospheric oxygenation at the onset of Earth’s Great Oxidation forced marine anoxia. Journal of South African Geology (Submitted; 2023).
  • Zhang, X., Paoletti, M.M., Izon, G., Fournier, G.P., Summons R.E. Late acquisition of the rTCA carbon fixation pathway by Chlorobi. Nature Ecology and Evolution (2023). DOI: 10.1038/s41559-023-02147-0
  • Havsteen, J.C., Kleinhanns, I.C.,  Schröder, S., Eickmann, B.,  Izon, G., Gogouvitis, M.D., Ngobeli, R., Beukes, N.J., Schoenberg., R (2023) Evidence for contemporaneous deposition of the Duitschland and Rooihoogte formations (Transvaal Supergroup): Implications for tempo and mode of Earth’s Great Oxidation. Precambrian Research, 391. DOI: 10.1016/j.precamres.2023.107055
  • Rezeau, H., Jagoutz, O., Beaudry, P., Izon, G., Kelemen, P., Ono, S. (2023) The role of immiscible sulfides for sulfur isotope fractionation in arc magmas: Insights from the Talkeetna island arc crustal section, south- central Alaska.  Chemical Geology, 619. DOI: 10.1016/j.chemgeo.2023.121325
  • Uveges, B.T., Izon, G., Ono, S., Beukes, N.J., Summons, R.E. (2023) Reconciling discrepant minor sulphur isotope records of the Great Oxidation Event. Nature Communications, 14: 279. DOI: 10.1038/s41467-023-35820-w.
  • Gong, S., Izon, G., Peng, Y., Cao, Y., Liang, Q., Peckmann, J., Chen, D., Feng, D., (2022) Multiple sulfur isotope systematics of pyrite for tracing sulphate-driven anaerobic oxidation of methane. Earth and Planetary Science Letters, 597, 117827. DOI:10.1016/j.epsl.2022.117827
  • Izon, G., Luo, G., Uveges, B.T., Beukes, N.J., Kitajima, K., Ono, S., Valley, J.W., Ma, X., Summons, R.E. (2022) Bulk and Grain-Scale Minor Sulfur Isotope Data Reveal Complexities in the Dynamics of Earth’s Oxygenation. Proceedings of the National Academy of Sciences, 119, e2025606119. DOI:10.1073/pnas.2025606119
  • Ranta, E., Gunnarsson-Robin, J., Halldórsson, S.A., Ono, S., Izon, G., Jackson, M.G., Reekie, C.D.J., Jenner, F., Guðfinnsson, G.H., Jónsson, O.P., Stefánsson A. Primordial and recycled sulfur sampled by the Iceland mantle plume. Earth and Planetary Science Letters584, 117452. DOI:10.1016/j.epsl.2022.117452. Pre-print archived at
  • Dong, A., Sun, Z., Kendall, B., Izon, G., Cao, H., Li, Z., Ma, X., Yin, X., Qiu, Z., Zhu, X-K., Bekker, A., Poulton S.W. (2022) Insights from modern diffuse-flow hydrothermal systems into the origin of post-GOE deep-water Fe-Si precipitates. Geochimica et Cosmochimica Acta, 317, 1–17. DOI:10.1016/j.gca.2021.10.001
  • Liu, J., Pellerin, A., Antler, G., Izon, G., Findlay, A.J., Røy, H., Ono, S., Kasten, S., Turchyn, A.V., Jørgensen, B.B. (2021) Early diagenesis of sulfur in Bornholm Basin sediments: The role of upward diffusion of isotopically “heavy” sulfide. Geochimica et Cosmochimica Acta, 313, 359–377. DOI:10.1016/j.gca.2021.08.018
  • Zavina-James, N.A.V., Zerkle, A.L., Steele, R.C.J., Warke, M., Izon, G., Savage, P.S., (2021) A copper isotope investigation of methane cycling in Late Archaean sediments. Precambrian Research; 317, 106267. DOI: 10.1016/j.precamres.2021.106267
  • Zhang, X., Bianchi, T., Hanna, A., Shields, M., Izon, G., Hutchings, J., Ping C-L., Kanevskiy M., Haghipour N., Eglinton T. (2021) Recent Warming Fuels Increased Organic Carbon Export from Arctic Permafrost. AGU Advances, 2, e2021AV000396. DOI:1029/2021AV000396 [Editor’s Highlights]
  • Liu, J., Antler, G., Pellerin, A., Izon, G., Dohrmann, I., Findlay, A.J., Røy, H., Ono, S., Turchyn, A.V., Kasten, S., Jørgensen, B.B. (2021) Isotopically ‘heavy’ pyrite in marine sediments due to high sedimentation rates and non-steady-state deposition. Geology, 49 (7), 816–821.  DOI: 10.1130/G48415.1 [Cover Image]
  • Zerkle, A.L., Yin, R., Chen, C., Li, X., Izon, G., Grasby, S.E. (2020) Anomalous fractionation of mercury isotopes in the Late Archean atmosphere. Nature Communications, 11,  DOI: 10.1038/s41467-020-15495-3
  • Liu, J., Pellerin, A.Izon, G., Wang, J., Antler, G., Liang, J., Su, P., Jørgensen, B.B., Ono, S. (2020) The multiple sulphur isotope fingerprint of a sub-seafloor oxidative sulphur cycle driven by iron. Earth and Planetary Science Letters, 536, 116165. DOI:10.1016/j.epsl.2020.116165.
  • Yang, J., Junium, C.K., Grassineau, N.V., Nisbet, E.G., Izon, G., Mettam, C., Martin, T., Zerkle, A.L. (2019) Ammonium availability in the Late Archaean nitrogen cycle. Nature Geoscience, 12, 553–557. DOI: 1038/s41561-019-0371-1
  • Dong, A., Zhao, S., Louchouarn, P., Izon, G., Zhang, H., Jiang, X. (2019). The distribution and accumulation of mercury and methylmercury in surface sediments beneath the East China Sea. Environmental Science and Pollution Research, 26 (5)4667–4679. DOI:1007/s11356-018-3880-3.
  • Liu, J., Izon, G.,Wang, J., Antler, G., Wang, Z., Zhao, J., Egger, M. (2018), Vivianite formation in methane-rich deep-sea sediments from the South China Sea. Biogeosciences, 15, 6329–6348. DOI:5194/bg-15-6329-2018.
  • Paiste, K., Lepland, A., Zerkle, A.L., Kirsimäe, K., Izon, G., Patel, N. K., McLean, F., Kreitsmann, T., Mänd, K., Bui, T.H., Romashkin, A.E., Rychanchik, D.V., Prave, A.R. (2018) Multiple sulphur isotope records tracking basinal and global processes in the 1.98 Ga Zaonega Formation, NW Russia. Chemical Geology, 499, 151–164. DOI:1016/j.chemgeo.2018.09.025.
  • Luo, G., Junium, C.J., Izon, G., Ono, S., Beukes, N.J., Algeo, T.J., Cui, Y., Xie, S., Summons, R.E. (2018), Nitrogen fixation sustained productivity in the wake of the Palaeoproterozoic Great Oxygenation Event. Nature Communications9, Article number:  DOI:10.1038/s41467-018-03361-2.
  • Mettam C., Zerkle, A.L., Claire, M.W., Izon, G., Junium, C.J., Twitchett, R.T., (2017) High-frequency fluctuations in redox conditions during the latest Permian mass extinction. Palaeogeography, Palaeoclimatology, Palaeoecology485; 210–230. DOI:1016/j.palaeo.2017.06.014.
  • Izon, G., Zerkle, A.L., Williford, K.H., Farquhar, J., Poulton, S.W. and Claire, M.W. (2017), Biological regulation of atmosphere chemistry en route to planetary oxygenation. Proceedings of the National Academy of Sciences, DOI:1073/pnas.1618798114.
  • Izon, G., Zerkle, A.L., Zhelezinskaya, Y., Farquhar, J., Newton, R.J., Poulton, S.W., Eigenbrode, J.L & Claire. M.W. (2015), Multiple Oscillations in Neoarchaean Atmospheric Chemistry. Earth and Planetary Science Letters, 431; 264–273.
  • Miller, C.S., Leroy, S.A.G., Izon, G., Lahijani, H.A.K., Marret, F., Cundy, A.B. & Teasdale, P.A. (2013), Palynology: A tool to identify abrupt events? An example from Chabahar Bay, southern Iran. Marine Geology, 337195–201.
  • Goldberg, T., Gordon, G., Izon, G., Archer, C., Pearce, C.R., McManus, J., Anbar, A., and Rehkämper, M. (2013). Resolution of inter-laboratory discrepancies in Mo-isotope data: An intercalibration. Journal of Analytical Atomic Spectrometry, 28724–735.
  • Bond, D.P., Wignall, P.B., Wang, W., Izon, G., Jiang, H., Lai, X., Sun, Y., Newton, R.J., Shao, L., Vedrine, S., Cope, H., (2010). Mid-Capitanian middle Permian mass extinction and carbon isotope record of South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 292; 282–294.
  • Wignall, P.B., Sun, Y., Bond, D.P., Izon, G., Newton, R.J., Vedrine, S., Widdowson, M., Ali, J.R., Lai, X., Jiang, H., Cope, H., Bottrell, S.H. (2009). Volcanism, mass extinction, and carbon isotope fluctuations in the Middle Permian of China. Science324; 1179–1182.

Equal contribution authorship