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C324: Sniffing Hydrated Minerals for Life (Lead Supervisor: David Hodell, Earth Sciences)

Supervisors: David Hodell (Earth Sciences), Markus Kalberer (Chemistry) and Rod Jones (Chemistry)

Importance of the area of research:

The current search for life on Mars is centred on analysis of the Martian atmosphere for the presence of biogenic gases (e.g., methane).  There was much excitement when a large methane spike was observed by the Curiosity rover two years ago, but the transient event has not recurred. Instead, gases trapped in inclusions contained within hydrated minerals may hold important information about the gas composition of the environment at the time of mineral formation. Hydrated minerals require water to form and trap gases in inclusions.  For example, evolved gas analysis of natural gypsum samples has shown that they contain carbon dioxide, methane, hydrogen sulfide, and volatile organic compounds that are released upon dehydration. These gases are absent or found at much lower concentrations in gypsum formed inorganically.  This project will analyse the composition and isotope ratios of evolved gases in hydrated minerals to assess their potential for detecting chemical signatures of life.

Project summary:

Evolved gas analysis of gas inclusions contained in hydrated minerals may provide vital information in the search for life on Mars. In the absence of oxygen, microbes on Earth reduce iron, sulphur and carbon dioxide to produce energy. These biochemical processes produce gases such as H2S and CH4 that are depleted in the light isotopes of sulfur and carbon. These gases, which are trapped in mineral inclusions, form in environments where sulfate reduction and methanogenesis are actively occurring. In addition, the oxygen and hydrogen isotopic composition of the hydration water provides environmental information about the water from which the mineral was precipitated (Gazguez et al., 2015; Evans et al., 2015).

What the student will do:

The student will extract gases from hydrated minerals formed in different environments of deposition and ages, and determine their composition and isotopic ratios (d13C of the CO2 and CH4, and the d34S of H2S). The focus will initially be on gypsum (CaSO4 2H2O) that is abundant on both Earth and Mars and is known to possess gas inclusions containing carbon dioxide, methane, hydrogen sulfide, and volatile organic compounds. Experiments will also be conducted using the Mars simulator at the Open University to determine if inclusions retain their original gas content when subjected to variations in Martian temperatures and pressures.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Ming, D.W. et al., Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale Crater, Mars. Science, 343,1-9, (24 Jan 2014). 

Gázquez, F., Mather, I., Rolfe, J., Evans, N.P., Herwartz, D., Staubwasser, M., Hodell, D.A., Simultaneous analysis of 17O/16O, 18O/16O and 2H/1H of gypsum hydration water by cavity ringdown laser spectroscopy. Rapid Communications in Mass Spectrometry, 29, 1997–2006 (2015).

Evans, N.P., Turchyn, A.V.,  Gázquez, F., Bontognali, T.R.R., Chapman, H.J., and Hodell, D.A..  Coupled measurements of d18O and dD of hydration water and salinity of fluid inclusions in gypsum from the Messinian Yesares Member, Sorbas Basin (SE Spain). Earth Planet. Sci. Letts., 430, 499–510 (2015).

Follow this link to find out about applying for this project

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