Hematite Is a Mineralogical Marker of Ancient Climate Change on Mars

Marek Szczerba; Tanya S Peretyazhko; Elizabeth B Rampe; Thomas F Bristow; Benjamin M Tutolo; Douglas W Ming; Dave T Vaniman; Richard V Morris; Silas J Ralston; Nikole C Haney; Bum Soo Kim; David F Blake; Steve J Chipera; Robert T Downs; Robert M Hazen; Shaunna M Morrison; Allan H Treiman; Albert S Yen; Valerie M Tu; Michael T Thorpe; Cherie N Achilles; David J Des Marais; John P Grotzinger; Nicholas Castle; Patricia C Craig; Elisabeth M Hausrath; Sarah L Simpson

NASA NTRS · 20260002891

Hematite Is a Mineralogical Marker of Ancient Climate Change on Mars

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Abstract

The ancient climate of Mars changed from warm to cold surface conditions. This climate transition is demonstrated by geomorphological evidence, but lacks suitable mineralogical indicators. We investigate the crystallographic properties of hematite (iron oxide) in Gale crater, measured by the Curiosity rover, and compare them to laboratory experiments. Hematite crystallite sizes are ~5 to ~65 nm in the oldest sedimentary rocks investigated by the rover (the Murray formation) and <10 nm in the younger overlying strata (Mirador and Carolyn Shoemaker formations). We attribute the larger crystallites in the Murray formation to post-depositional coarsening by groundwater in warm and wet conditions, which persisted for several million years. Hematite with small crystallites co-occurs with goethite (iron oxyhydroxide) in the overlying layers, consistent with colder and water- limited conditions.

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Marek Szczerba, Tanya S Peretyazhko, Elizabeth B Rampe, Thomas F Bristow, Benjamin M Tutolo, Douglas W Ming, Dave T Vaniman, Richard V Morris, Silas J Ralston, Nikole C Haney, Bum Soo Kim, David F Blake, Steve J Chipera, Robert T Downs, Robert M Hazen, Shaunna M Morrison, Allan H Treiman, Albert S Yen, Valerie M Tu, Michael T Thorpe, Cherie N Achilles, David J Des Marais, John P Grotzinger, Nicholas Castle, Patricia C Craig, Elisabeth M Hausrath, Sarah L Simpson. 2026-08-01. Hematite Is a Mineralogical Marker of Ancient Climate Change on Mars. https://ntrs.nasa.gov/citations/20260002891

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