Research Fellow in Isotope Geochemistry - AR1837SB

University of St Andrews - Department of Earth and Environmental Sciences

Triple oxygen isotope geochemistry and the evolution of the atmosphere

Atmospheric oxygen concentrations have changed dramatically over Earth’s 4.5 billion year history. Earth’s atmosphere was devoid of free oxygen for the first 2 billion years of planetary history, with two apparent increases in concentration at ~2.4 and ~0.55 billion years ago. Extreme climatic effects and massive reorganization of biogeochemical cycles accompanied both periods of oxygenation. Despite these profound influences on the Earth system, we lack fundamental quantitative constraints on atmospheric oxygen levels over the past 2.4 billion years. This project will develop new analytical methods to measure triple oxygen isotope geochemistry in key sedimentary samples and increase the database of measurements from which fundamental constraints can be derived.

Recent advances in Cavity Ringdown Spectroscopy have enabled the determination of 17-O excess in H2O to 10 permeg precision. The fellow will develop classic methodology to induce isotope exchange between nitrate, sulfate, perchlorate and water, and quantify the 17-O excess via pre-post measurements on the H2O. This new method (IE-CRDS) should enable comparable measurements for samples with large 17-O excess, at a fraction of the cost and effort of classic methods. Additional measurements will be carried out in Louisiana, U.S.A., using the IRMS technique pioneered by project-partner Dr Huiming Bao.

The IE-CRDS and IRMS methodologies will be used to analyze 17-O excess in geological samples spanning post-GOE Earth history. The lab already has exciting samples from never-before-analyzed ~ 2.2 – 2.0 Ga evaporites obtained from new drill core in the Karelia province, Russia. To complement those, the fellow will conduct field work in northwest Namibia and the southwest US to obtain sulfate-related evaporitic samples spanning the Neoproterozoic record of Snowball Earth and the rise of animals. Sampling campaigns to the western Alps/Apennines and the southwestern USA will enable collection of arid deposits of the Permo-Triassic, spanning the largest extinction event in Earth history. Project partner Dr. Tony Prave will help guide sampling strategies. An additional field excursion to the Atacama desert, Chile will collect soil samples spanning a hyper-arid to arid rainfall gradient. These samples will provide a critical ground-truth needed to validate predictive oxygen isotope photochemical models, which will be developed concurrently by the research group.

We are looking to appoint a Postdoctoral Research Fellow with experience in field geology and isotope geochemistry. This is a 36 month, full time position, starting salary, £31,656 - £37,768 per annum, depending upon experience. For any enquiries about the project please contact Mark Claire ( A start date is anticipated for January 1st, 2017, but is negotiable.

The University of St Andrews is committed to promoting equality of opportunity for all, which is further demonstrated through its working on the Gender and Race Equality Charters and being awarded the Athena SWAN award for women in science, HR Excellence in Research Award and the LGBT Charter;

Interview Date:  14 November 2016

We encourage applicants to apply online at, however if you are unable to do this, please call +44 (0)1334 462571 for an application pack.          

The University of St Andrews is a charity registered in Scotland (No SC013532)

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