Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near‐surface water on early Mars |
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| Authors: | Alberto G FAIRÉN James M DOHM Victor R BAKER Shane D THOMPSON William C MAHANEY Kenneth E HERKENHOFF J Alexis P RODRÍGUEZ Alfonso F DAVILA Dirk SCHULZE‐MAKUCH M Ramy EL MAARRY Esther R UCEDA Ricardo AMILS Hirdy MIYAMOTO Kyeong J KIM Robert C ANDERSON Christopher P McKAY |
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| Institution: | 1. SETI Institute, 189?N Bernardo Ave, Mountain View, California 94043, USA;2. Space Science and Astrobiology Division, NASA Ames Research Center, MS 245‐3, Moffett Field, California 94035, USA;3. Department of Hydrology and Water Resources, The University of Arizona, Tucson, Arizona 85721, USA;4. School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA;5. Quaternary Surveys, 26 Thornhill Ave., Thornhill, Ontario, Canada, L4J 1J4;6. Astrogeology Science Center, U.S. Geological Survey, 2255?N. Gemini Drive, Flagstaff, Arizona 86001, USA;7. Planetary Science Institute, 1700 E. Ft. Lowell Rd., Suite 106, Tucson, Arizona 85719, USA;8. School of Earth and Environmental Sciences, Washington State University, Pullman, Washington 99163, USA;9. Max‐Planck Institut für Sonnensystemforschung, 37191 Katlenburg‐Lindau, Germany;10. Centro de Astrobiología (INTA–CSIC), Ctra. Ajalvir km 4, Torrejón de Ardoz, 28850, Madrid, Spain;11. The Museum, The University of Tokyo, Tokyo, Japan;12. Korea Institute of Geoscience and Mineral Resources, Daejeon, Korea;13. Jet Propulsion Laboratory, Pasadena, California 91109, USA |
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| Abstract: | Abstract– Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25 km‐long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10–80 m of deflation in the last 3–3.5 Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface. |
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