EGU22-11272, updated on 28 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Micro-scale characterization of vermiculite-rich sample from Granby Tuff, an analogue to Oxia Planum clays

Benjamin Bultel1, Agata Krzesinska1, Marco Veneranda2, Damien Loizeau3, Cédric Pilorget3, Vincent Hamm3, Lionel Lourit3, Guillaume Lequertier3, Jean-Pierre Bibring, and Stephanie C. Werner1
Benjamin Bultel et al.
  • 1Center for Earth Evolution and Dynamics (CEED), Beyond Earth, Oslo, Norway (
  • 2Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Ave. Francisco Vallés, 8, 47151, Boecillo, Spain
  • 3Institute of Space Astrophysics, CNRS/ Paris-Sud University, France

In 2022, ESA/ROSCOSMOS will launch ExoMars2022 rover mission to Mars. The selected landing site for the mission is Oxia Planum, a Noachian, phyllosilicate-bearing plain located between Mawrth Vallis and Ares Vallis. The Fe,Mg-rich clay mineral detected at Oxia Planum are one of the largest exposures of this type on Mars. They clearly record past water-rock interactions and as such are promising target to answer scientific questions that are the objectives of the ExoMars 2022 mission in terms of past water-rich environment and both ancient and present habitability of the planet.

NIR spectral features of the phyllosilicates at Oxia suggest some kind of Fe-rich vermiculite and/or saponite. Survey of Fe-rich terrestrial vermiculite-bearing rocks and characterization by powder near-infrared and X ray diffraction analyses (Krzesinska et al, 2021) showed that the best spectral analogy is shown by the basaltic tuffs from Granby, Massachusetts, USA. The tuffs have been altered and Fe-rich clays resides in amygdales of supposedly hydrothermal origin (April and Keller, 1991).

The analogue was incorporated to the Planetary Terrestrial Analogue Library (PTAL) collection (Dypvik et al., 2021, As a part of collection, it is further characterized for purposes of supporting the ExoMars mission science.

As shown by bulk analysis of powdered samples, Granby tuffs represent fine-scale mixture of phyllosilicates (Krzesinska et al., 2021). Based on bands between 2.3 and 2.5µm in NIR, vermiculite and saponite are intergrowing with various proportions. For Oxia Planum, better spectral match is shown by samples dominated by vermiculite rather than mixed with saponite.

Here we report an in-situ, micron-scale combined analysis on the same sample by the instrument of MicrOmega (NIR), RLS (RAMAN) completed by sub-micron EDX analysis. Such analysis allows a more detailed characterization of phyllosilicate constituents and understanding their spectral manifestation. This is important to prepare the future in situ scientific investigations on Mars and will also bring a better understanding of the Granby clays that could represent a unique bridge of solid solution between chlorite and saponite (April and Keller, 1991).

How to cite: Bultel, B., Krzesinska, A., Veneranda, M., Loizeau, D., Pilorget, C., Hamm, V., Lourit, L., Lequertier, G., Bibring, J.-P., and Werner, S. C.: Micro-scale characterization of vermiculite-rich sample from Granby Tuff, an analogue to Oxia Planum clays, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11272,, 2022.