Signs of life in Paleoarchean chemical sedimentary rocks: a strategy to search for extra-terrestrial life

Theme: Past Life & Environments

Primary Supervisor:

Dominic Papineau

Earth Sciences, UCL

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Secondary Supervisor:

Matthew Powner

Chemistry, UCL

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Project Description:

Evidence of life in early Archean rocks is challenging to decipher because of the many possible sources of biological and non-biological organic matter in metamorphosed sedimentary rocks. This problem is important because determining that life on Earth originated within only a few hundred million years, increases the probability of life originating elsewhere, and thus, is an important testbed to search for fossil extra-terrestrial life. The project will seek to perform a detailed characterization of the nature of microscopic particles of organic matter in Palaeoarchean chemical sedimentary rocks from Western Australia, South Africa, and India. Laboratory analyses will consist in documenting, by optical microscopy and micro-Raman imaging, the mineral associations with organic matter in hydrothermal-sedimentary chert. Focus will be placed on various types of sedimentological-diagenetic microstructures, including some highly debated microfossil-like structures. These analyses will be complemented by the characterization of molecular compositions by Gas Chromatography – Mass Spectrometry (GC-MS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Nuclear Magnetic Resonance (NMR), and synchrotron-based Scanning Transmission X-ray Microscopy (STXM). Results will allow the recognition of indigenous organic matter and a critical evaluation of its composition in relation to the metamorphic history of the rocks. Whether or not early microbial ecosystems can be recognized in Paleoarchean chert, the analytical and scientific strategy will contribute to pave the way to search for extra-terrestrial life on other ancient planetary surfaces, including for Mars.

Policy Impact of Research:

The research will involve analyses with a range of instruments and produce multi-disciplinary datasets and training. It is an opportunity to explore the topics of the origin of life, biosignatures for exobiology, and the earliest evolution of biogeochemical cycles.


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