Deadline for application: 21 April 2014
Start date: 1 October 2014
Duration of studentship: 4 years (includes stipend and fees)

Biosignatures in Earth’s oldest sedimentary rocks - When “Nano” meets “Geo”
This project will involve a field component and the use of state-of-the-art micro-analytical methods for the ‘nanobiogeochemical’ characterization of ancient organic matter. This project will be conducted primarily in the London Centre for Nanotechnology, but instruments located at Imperial College and Open University will also be used for this research. The overarching goal of this doctoral project is to trace the origin of organic matter as a possible biosignature of early life on Earth. Studying traces of life in some of the oldest sedimentary rocks on Earth is challenging because of the possibility of natural contamination by young fluids in the crust and alteration minerals that may be similar to biologically-produced ones. This quest to understand our origins is therefore astrobiological in nature and can be seen as preparatory work to study future Mars Sample Return.

This exciting project will involve the systematic study of organic matter in petrographic thin sections from a range of Precambrian sedimentary rocks such banded iron formations, cherts, stromatolitic carbonates, and others. Various micro-analytical tools will be used to characterize the molecular, elemental, isotopic, and structural characteristics of the organic matter. The student candidate will learn to characterize organic matter with micro-analytical techniques such as laser Raman micro-spectroscopy, Scanning and Transmission Electron Microscopy (SEM and TEM), Secondary Ion Mass Spectrometry (SIMS), dual beam Focused Ion Beam – SEM (FIB), and Time-of-Flight Secondary Ion Mass spectrometry (ToF-SIMS).
All these techniques are well developed and have been used in a correlated manner to study graphitic carbon in some of the oldest metasedimentary rocks (Papineau et al., 2010a; 2010b; 2011). Results have to first confirm that the organic matter is indigenous to the rock and not from a younger source that could have been emplaced late in the history of the rock, which would have no bearing on the nature of primitive Earth life. Then the geochemical composition has to be consistent with a biological origin, in which case could be informative of the kinds of microorganisms that evolved on the early Earth and the nature of these mysterious environments in which life originated (e.g. Wacey et al., 2014). However, the scientific contribution would be equally important if the organic matter is shown to not be indigenous or to be non-biological in origin, because we need this benchmark in order to prepare for the analysis of samples from Mars, a planet where we do not yet know whether life ever existed.

Papineau, D., DeGregorio, B.T., Cody, G.D., O'Neil, J., Steele, A., Stroud, R.M., and Fogel, M.L.
(2011) Young poorly crystalline graphite in the >3.8 Gyr old Nuvvuagittuq banded iron
formation, Nature Geoscience 4, 376-379.
Papineau, D., DeGregorio, B.T., Cody, G.D., Fries, M.D., Mojzsis, S.J., Steele, A., Stroud, R.M., and
Fogel, M.L. (2010) Ancient graphite in the Eoarchean quartz-pyroxene rock from Akilia in
southwest Greenland I: Petrographic and spectroscopic characterization. Geochimica et
Cosmochimica Acta 74, 5862-5883.
Papineau, D., DeGregorio, B.T., Stroud, R.M., Steele, A., Pecoits, E., Konhauser, K., Wang, J., and
Fogel, M.L. (2010) Ancient graphite in the Eoarchean quartz-pyroxene rock from Akilia in
southern West Greenland II: Isotopic and chemical compositions and comparison with
Paleoproterozoic banded iron formations. Geochimica et Cosmochimica Acta 74, 5884-5905.
Wacey, D., Menon, S., Green, L., Gerstmann, D., Kong, C., McLoughlin, N., Saunders, M., and
Brasier, M. (2012) Taphonomy of very ancient microfossils from the 3400 Ma Strelley Pool
Formation and 1900 Ma Gunflint Formation: New insights using a focused ion beam.
Precambrian Research 220-221, 234-250.

Contact: Dr Dominic Papineau