A Multidisciplinary Study of Biomarkers in Hydrothermal Deposits: Applications to the Search for Life on Mars

• Main Author: Preston , Louisa Jane
• Other Authors: Genge, Matthew
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Imperial College London 2008
• Subjects: New Zealand; Iceland
• Online Access: http://hdl.handle.net/10044/1/4276; https://doi.org/10.25560/4276

Hydrothermal systems have been suggested as suitable environments for the appearance of life on the Early Earth and may provide habitats for microorganisms on Mars. The deposits created by these systems are preserved in the geological record. This research investigates the key mineralogical, textural and biological markers found in terrestrial hydrothermal deposits that can be used as analogues in the search for evidence of life on Mars. Samples of silica sinter from Iceland and New Zealand, the Rhynie Chert 396 Ma old deposit from Aberdeenshire and hydrothermally altered impactites from the Chicxulub impact crater have been analysed to understand the mineralogical properties unique to the different hydrothermal conditions and the evidence of extant or extinct microorganisms within them. Re-colonisation of basaltic substrates by hot spring-derived cultures was also carried out. This research was conducted using a multidisciplinary approach with the analytical techniques and instruments involved currently used for in-situ and orbital observations of planetary bodies. The principal techniques, Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography Mass Spectrometry (GCMS), were used due to their combined capabilities in the identification of a variety of rocks and minerals, and a wide range of organic compounds. This PhD research has shown that FTIR in particular is an exceptional analytical technique for use in astrobiological investigations. This research has characterised hydrothermal deposits of different ages and created by different processes on Earth to ascertain their potential for preserving organic compounds in similar deposits on Mars. Results indicate that siliceous hydrothermal deposits of recent and ancient formation yield biomolecular evidence for past and present microbial colonisation as do hydrothermally altered impact deposits and re-colonised basaltic substrates. The identification of mineralogical and biological information using FTIR reflectance spectroscopy has wide implications in the search for life on Mars and other planetary bodies.