22-EPN3-127: Silcrete deposits of the Kalahari Desert as potential analogs for silica-rich deposits on Mars
April 26, 2024

22-EPN3-127: Silcrete deposits of the Kalahari Desert as potential analogs for silica-rich deposits on Mars

Visit by Maxime Pineau (Laboratoire d’Astrophysique de Marseille (LAM), France) and Simon Gouzy (Laboratoire de Planétologie et Géosciences (LPG), France) to TA1.5 Makgadikgadi Salt Pans (Botswana).
Dates of visit: 21-28 August January 2023

Report Summary: Hydrated silica occurs in various forms depending on the geological context and as such are good tracers for paleoenvironmental reconstitutions on Earth and Mars, as well as a prime exobiological target. Observed on Mars since the early 2000’s, hydrated silica minerals have been used to describe aqueous geological processes in diverse regions. However, geological origins of some deposits are still misunderstood because no satisfactory terrestrial analogues were found. Likewise, the exobiological potential of hydrated silica as a prime host of Mars organic matter remains to be fully ascertained.

The Makgadikgadi Salt Pans show a very high potential to be considered as a terrestrial analogue site for Mars hydrated silica, especially in fluvio-lacustrine geological settings. Maxime Pineau (LAM), Simon Gouzy (LPG), plus 2 other colleagues (Vassilissa Vinogradoff (PIIM) and John Carter (LAM)), spent 9 days at the pans (15 different locations) and sampled numerous samples (over 80s) of silicified clastic sedimentary rocks (i.e., silcretes) and conducted preliminary visible-near infrared spectra with a portable spectrometer.

Field observations and spectral analyses confirm the large amount of amorphous to (micro-)crystalline silica in the samples, along with different clays (e.g., glauconite, sepiolite) and salts (e.g., sulfates). This type of mineralogy, possibly indicating a formation in a fluvio-lacustrine context in semi-desert environments, is reminiscent of some silica-rich deposits on Mars in locations interpreted as potential paleo-lakes. These observations will be completed by further laboratory measurements (spectroscopy, microscopy, geochemical and organic analyses) in order to perform advanced studies in terrestrial geology, comparative planetology (e.g., Mars’ geology) and astrobiological exploration.

Read the full scientific report with kind permission by Maxime Pineau and Simon Gouzy.