Abstract
AbstractImpact craters and associated hydrothermal systems are regarded as sites within which life could originate on Earth, and on Mars. The Haughton impact crater, one of the most well preserved craters on Earth, is abundant in Ca-sulphates. Selenite, a transparent form of gypsum, has been colonized by viable cyanobacteria. Basement rocks, which have been shocked, are more abundant in endolithic organisms, when compared with un-shocked basement. We infer that selenitic and shocked gypsum are more suitable for microbial colonization and have enhanced habitability. This is analogous to many Martian craters, such as Gale Crater, which has sulphate deposits in a central layered mound, thought to be formed by post-impact hydrothermal springs. In preparation for the 2020 ExoMars mission, experiments were conducted to determine whether Raman spectroscopy can distinguish between gypsum with different degrees of habitability. Ca-sulphates were analysed using Raman spectroscopy and results show no significant statistical difference between gypsum that has experienced shock by meteorite impact and gypsum, which has been dissolved and re-precipitated as an evaporitic crust. Raman spectroscopy is able to distinguish between selenite and unaltered gypsum. This shows that Raman spectroscopy can identify more habitable forms of gypsum, and demonstrates the current capabilities of Raman spectroscopy for the interpretation of gypsum habitability.
Highlights
Impact generated sulphate deposits and significance for lifeHydrothermal deposits within craters on Mars represent one of the most important targets in the search for life on Mars (Cabrol et al 1999; Newsom et al 2001)
Sample SH1 has a fragment of gypsum, and the spectrum shows a v1 band position of 1007.52 cm−1, which is indicative of gypsum, it does not show the presence of water molecules at the expected wavelength
A range of gypsum samples were analysed using Raman spectroscopy, to determine if this technique can differentiate between Ca-sulphates, which have enhanced habitability, and those that do not
Summary
Impact generated sulphate deposits and significance for lifeHydrothermal deposits within craters on Mars represent one of the most important targets in the search for life on Mars (Cabrol et al 1999; Newsom et al 2001). Over 60 impact craters with associated hydrothermal activity have been discovered on Earth, and given the long bombardment history of Mars, impact craters could be a common site to search for life (Chapman & Jones 1977; Naumov 2002). The Eocene Haughton impact crater, located on Devon Island in the Canadian High Arctic Archipelago, provides a useful analogue site to study post impact sulphate deposits (Sherlock et al 2005). It is exceptionally well preserved, which is why it has been extensively studied, and has examples of sulphate deposits containing microbial life
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