¹Alexandre V. Andronikov,¹Irina E. Andronikova,¹Ondrej Pour,¹Petr Bohdalek
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14347]
¹Division of Geochemistry and Laboratories, Czech Geological Survey, Prague, Czech Republic
Published by arrangement with John Wiley & Sons

We have analyzed in situ mineral phases in a Potůčky fragment of the stony-iron IVA-an meteorite Steinbach for trace-element compositions. The studied fragment contains silicate grains (pyroxene and tridymite) interspersed with grains of metal (kamacite, plessite, and taenite) displaying Widmanstätten pattern and troilite. Multiple inclusions of chromite, troilite, and bi-mineral troilite + taenite assemblages were observed within some pyroxene grains. The data on variations in trace-element compositions in different meteorite phases are consistent with a number of models, suggesting the involvement of several processes in the generation of the lithologies presently observed in the Potůčky meteorite. These processes might have involved fractional crystallization of silicate liquid, collision, impact, shock melting, and cooling. As a result of such processes, specific trace-element composition of different mineral phases was formed. Trace-element compositions of metals and sulfides from the Potůčky meteorite are very similar to those for minerals from the LL ordinary chondrite, suggesting LL-like asteroid as a parent body for the Potůčky (IVA-an) precursor material.

¹Carole Freissinet et al. (>10)
Proceedings of the National Academy of Science of the USA (PNAS) 122, e2420580122 Open Access Link to Article [https://doi.org/10.1073/pnas.2420580122]

¹Laboratoire Atmosphères et Observations Spatiales, Université Versailles St Quentin Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt 78280, France

Organic molecules preserved in ancient Martian rocks provide a critical record of the past habitability of Mars and could be chemical biosignatures. Experiments conducted by the Sample Analysis at Mars instrument onboard the Curiosity rover have previously reported several classes of indigenous chlorinated and sulfur-containing organic compounds in Gale crater sedimentary rocks, with chemical structures of up to six carbons. Here, we report the detection of decane (C10H22), undecane (C11H24), and dodecane (C12H26) at the tens of pmol level, released from the Cumberland drilled mudstone sample, using a modified SAM analytical procedure optimized for the detection of larger organic molecules. Laboratory experiments support the hypothesis that the alkanes detected were originally preserved in the mudstone as long-chain carboxylic acids. The origin of these molecules remains uncertain, as they could be derived from either abiotic or biological sources.