Lake- and groundwater-associated alteration of the olivine-rich Margin unit in Jezero crater, Mars
Abstract The Margin unit in Jezero crater, Mars, was explored by NASA’s Perseverance rover as orbital data suggested it may represent an ancient lake shoreline. Using SuperCam data, we evaluate the origin and alteration history of this enigmatic unit. Here, we show that the Margin unit explored at high elevations (>−2350 m) has a texture and chemistry indicative of a slow-cooled, crystalline, olivine-rich rock without significant water exposure. In contrast, exposures situated below the hypothesized Jezero paleolake’s second terrace level reveal a complex history of water-rock interaction, with signs of physical reworking near Neretva Vallis and the Western fan. We identify three main alteration episodes: first, neutral-to-alkaline CO 2 -rich fluids circulated within the bedrock, forming carbonate-rich ridges upon erosion. Then, exposure to the Jezero paleolake waters or changes in groundwater fluids remobilized carbonate and precipitated silica in the secondary pore spaces. Finally, late-stage hydrothermal fluids flowed through younger fractures, precipitating fluorite-bearing, Ca-sulfate mineral veins. This sequence of multiple fluid events driven by groundwater activity and exposure to the lake reinforces the Margin unit as a locality of astrobiological interest.
Authors
- E. Dehouck (ORCID: https://orcid.org/0000-0002-1368-4494)
- Julene Aramendia (ORCID: https://orcid.org/0000-0003-3728-8370)
- Lucia Mandon (ORCID: https://orcid.org/0000-0002-9310-0742)
- Clément Royer (ORCID: https://orcid.org/0000-0002-5472-7235)
- Juan Manuel Madariaga (ORCID: https://orcid.org/0000-0002-1685-6335)
- C. C. Bedford (ORCID: https://orcid.org/0000-0002-0783-1064)
- Susanne Schröder (ORCID: https://orcid.org/0000-0003-1870-3663)
- Kenneth H. Williford (ORCID: https://orcid.org/0000-0003-0633-408X)
- Elise Clavé (ORCID: https://orcid.org/0000-0002-9514-8168)
- Eleanor Louise Moreland (ORCID: https://orcid.org/0000-0003-0210-7576)
- Briony H. N. Horgan (ORCID: https://orcid.org/0000-0001-6314-9724)
- R. C. Wiens (ORCID: https://orcid.org/0000-0002-3409-7344)
- Kathryn M. Stack (ORCID: https://orcid.org/0000-0003-3444-6695)
- Linda C. Kah (ORCID: https://orcid.org/0000-0001-7172-2033)
- Pierre Beck (ORCID: https://orcid.org/0000-0002-6532-5602)
- A. Cousin (ORCID: https://orcid.org/0000-0001-7823-7794)
- Bradley Garczynski
- Eleni Ravanis (ORCID: https://orcid.org/0000-0002-0911-4341)
- Olivier Forni
- Alexander Jones
- Adrian Brown
- Stephanie Connell
Institutions
- Université Claude Bernard Lyon 1 (FR)
- École Normale Supérieure de Lyon (FR)
- University of Hawaiʻi at Mānoa (US)
- Centre National de la Recherche Scientifique (FR)
- Planetary Science Institute (US)
- Jet Propulsion Laboratory (US)
- University of the Basque Country (ES)
- Université Fédérale de Toulouse Midi-Pyrénées (FR)
- Purdue University West Lafayette (US)
- Université Paris-Saclay (FR)
- Institut d'Astrophysique Spatiale (FR)
- Institut de Planétologie et d'Astrophysique de Grenoble (FR)
- Czech Academy of Sciences, Institute of Geophysics (CZ)
- Institute of Space Science - INFLPR Subsidiary (RO)
- Blue Marble Space (US)
- Blue Marble Space Institute of Science (US)
- Institut de Recherche en Astrophysique et Planétologie (FR)
- Université de Toulouse (FR)
- Imperial College London (GB)
- Western Washington University (US)
- Rice University (US)
- University of Tennessee at Knoxville (US)
- Université Jean Monnet (FR)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Communications Earth & Environment
- Published
- 2026-09-21
- DOI
- https://doi.org/10.1038/s43247-026-03997-9
- Primary Topic
- Planetary Science and Exploration
- Type
- article
- Field-Weighted Citation Impact
- 0.00