Signs of life in Paleoarchean chemical sedimentary rocks

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:

The search for evidence of life on the earliest Earth is challenging because we cannot simply use uniformitarian principles that assume life existed then. This is because the existence of life itself is the main question at the centre of this rich debate. A thorough analytical approach is needed to uncover the true signatures of life in graphitic carbon that has been altered by metamorphism, which is the only archive available. There is also the problem that non-biological organic matter was the source of carbon in the environments of the origin of life. This project aims at characterizing the nature of microscopic particles of organic matter in Palaeoarchean chemical sedimentary rocks from Western Australia and South Africa. The research will consist in the petrography of organic matter by optical microscopy and micro-Raman imaging, which will provide detailed documentation of mineral associations with organic microstructures. 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 molecular composition in relation to the metamorphic history of the rocks and possible early microbial ecosystems, which will pave the way to search for extra-terrestrial life on other ancient planetary surfaces.

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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