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Clay minerals in delta deposits and organic preservation potential on Mars


Clay-rich sedimentary deposits are often sites of organic matter preservation1,2, and have therefore been sought in Mars exploration3. However, regional deposits of hydrous minerals, including phyllosilicates and sulphates4,5, are not typically associated with valley networks and layered sediments that provide geomorphic evidence of surface water transport on early Mars6,7,8. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)9 has recently identified phyllosilicates10 within three lake basins with fans or deltas that indicate sustained sediment deposition: Eberswalde crater7,11,12, Holden crater12,13 and Jezero crater14. Here we use high-resolution data from the Mars Reconnaissance Orbiter (MRO) to identify clay-rich fluvial–lacustrine sediments within Jezero crater, which has a diameter of 45 km. The crater is an open lake basin on Mars with sedimentary deposits of hydrous minerals sourced from a smectite-rich catchment in the Nili Fossae region. We find that the two deltas and the lowest observed stratigraphic layer within the crater host iron–magnesium smectite clay. Jezero crater holds sediments that record multiple episodes of aqueous activity on early Mars. We suggest that this depositional setting and the smectite mineralogy make these deltaic deposits well suited for the sequestration and preservation of organic material.

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Figure 1: Mineralogy and extent of the Jezero crater watershed.
Figure 2: MRO view of Jezero crater.
Figure 3: CRISM spectra compared with library9 mineral reflectance spectra.
Figure 4: Topography and stratigraphy of Jezero basin.


  1. Kennedy, M. J., Peaver, D. R. & Hill, R. J. Mineral surface control on organic carbon in black shale. Science 295, 657–660 (2002).

    Article  Google Scholar 

  2. Wattel-Koekkoek, E. J. W., Buurman, P., van der Plicht, J., Wattel, E. & van Breemen, N. Mean residence time of soil organic matter associated with kaolinite and smectite. Eur. J. Soil Sci. 54, 269–278 (2003).

    Article  Google Scholar 

  3. Farmer, J. D. & Des Marais, D. J. Exploring for a record of ancient Martian life. J. Geophys. Res. 104, 26977–26995 (1999).

    Article  Google Scholar 

  4. Bibring, J.-P. et al. Mars surface diversity as revealed by the OMEGA/Mars Express observations. Science 307, 1576–1581 (2005).

    Article  Google Scholar 

  5. Poulet, F. et al. Phyllosilicates on Mars and implications for early martian climate. Nature 438, 623–627 (2005).

    Article  Google Scholar 

  6. Carr, M. Water on Mars 229p (Oxford Univ. Press, New York, 1996).

    Google Scholar 

  7. Malin, M. C. & Edgett, K. S. Evidence for persistent flow and aqueous sedimentation on early Mars. Science 302, doi:10.1126/science.1090544 (2003).

  8. Irwin, R. P., Howard, A., Craddock, R. & Moore, J. M. An intense terminal epoch of widespread fluvial activity on early Mars: 2. Increased runoff and paleolake development. J. Geophys. Res. 110, E12S15 (2005).

    Article  Google Scholar 

  9. Murchie, S. et al. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on Mars Reconnaissance Orbiter (MRO). J. Geophys. Res. 112, E05S03 (2007).

    Article  Google Scholar 

  10. Mustard, J. F. et al. Hydrated silicate minerals on Mars observed by the CRISM instrument on MRO. Nature (submitted).

  11. Moore, J. M., Howard, A., Dietrich, W. E. & Schnek, P. M. Martian layered fluvial deposits: Implications for Noachian climate scenarios. Geophys. Res. Lett. 30, doi:10.1029/2003GL019002 (2003).

  12. Milliken, R. E. et al. Seventh Int. Conf. on Mars, July 9–13, 2007, Pasadena, California, abstract 3282 (2007).

  13. Grant, J. A. et al. HiRISE imaging of impact megabreccia and sub-meter aqueous strata in Holden Crater Mars. Geology 36, 195–198 (2008).

    Article  Google Scholar 

  14. Fassett, C. I. & Head, J. W. Fluvial sedimentary deposits on Mars: ancient deltas in a crater lake in the Nili Fossae region. Geophys. Res. Lett. 32, L14201 (2005).

    Article  Google Scholar 

  15. McEwen, A. S. et al. Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE). J. Geophys. Res. 112, E05S02 (2007).

    Article  Google Scholar 

  16. Greeley, R. & Guest, J. E. Geologic map of the eastern equatorial region of Mars. I-1802-B (US Geological Survey, 1987).

  17. Mustard, J. F. et al. Olivine and pyroxene diversity in the crust of Mars. Science 307, 1594–1597 (2005).

    Article  Google Scholar 

  18. Hoefen, T. M. et al. Discovery of olivine in the Nili Fossae Region of Mars. Science 302, 627–630 (2003).

    Article  Google Scholar 

  19. Hamilton, V. E. & Christensen, P. R. Evidence for extensive, olivine-rich bedrock on Mars. Geology 33, 433–436 (2005).

    Article  Google Scholar 

  20. Mangold, N. et al. Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 2. Aqueous alteration of the crust. J. Geophys. Res 112, E08S04 (2007).

    Article  Google Scholar 

  21. Kanner, L. C., Mustard, J. F. & Gendrin, A. Assessing the limits of the Modified Gaussian Model for remote spectroscopic studies of pyroxenes on Mars. Icarus 187, 442–456 (2007).

    Article  Google Scholar 

  22. Bishop, J. L., Pieters, C. M. & Edwards, J. O. Infrared spectroscopic analyses on the nature of water in montmorillonite. Clays and Clay Minerals 42, 702–716 (1994).

    Article  Google Scholar 

  23. Swayze, G. A. et al. in Proc. 11th JPL Airborne Earth Science Workshop (ed. Green, R. O.) 373–387 (JPL Publication 03–4, Pasadena, California, 2002).

  24. Nanson, G. C. Point bar and flood-plain formation of the meandering Beatton River north-eastern British Colombia, Canada. Sedimentology 27, 3–29 (1980).

    Article  Google Scholar 

  25. Mossop, G. D. & Flach, P. D. Deep channel sedimentation in the Lower Cretaceous McMurray Formation, Athabasca Oil Sands, Alberta. Sedimentology 30, 493–509 (1983).

    Article  Google Scholar 

  26. Garvin, J. B., Sakimoto, S. E. H. & Frawley, J. J. Sixth Int. Conf. on Mars, July 20–25, 2003, Pasadena, California, abstract 3277 (2003).

  27. Chamley, H. Clay Sedimentology 623p (Springer, Berlin, 1989).

    Book  Google Scholar 

  28. Chevrier, V., Poulet, F. & Bibring, J.-P. Early geochemical environment of Mars as determined from thermodynamics of phyllosilicates. Nature 448, 60–63 (2007).

    Article  Google Scholar 

  29. Huertas, F. J., Caballero, E., Jiménez de Cisneros, C., Huertas, F. & Linares, J. Kinetics of montmorillonite dissolution in granitic solutions. Appl. Geochem. 16, 397–407 (2001).

    Article  Google Scholar 

  30. Klein, H. P. The Viking Mission and the search for life on Mars. Rev. Geophys. 17, 1655–1662 (1979).

    Article  Google Scholar 

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Special thanks go to the entire MRO team: without their ongoing efforts, these new discoveries would not be possible. We especially recognize the efforts of the CTX and HiRISE teams for coordinated observations with CRISM. Special thanks to Gregg Swayze for numerous discussions on interpreting CRISM spectra from the Nili Fossae region. The comments of reviewers Vincent Chevrier and Victor Baker helped improve this manuscript.

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Correspondence to Bethany L. Ehlmann.

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Ehlmann, B., Mustard, J., Fassett, C. et al. Clay minerals in delta deposits and organic preservation potential on Mars. Nature Geosci 1, 355–358 (2008).

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