Post by Dr Mariam Sowe
Candor Chasma is situated in the central Valles Marineris (Image 1). It is characterised by Interior Layered Deposits (ILDs) that are exposed on its valley floor. ILDs are closely connected to sulphate minerals and iron oxide [Christensen et al., 2001; Gendrin et al., 2005; Mangold et al., 2007]. Using high resolution images and elevation data from the Mars Express HRSC experiment [Jaumann et al., 2007] their layer geometry can be measured.
Interior layered deposits mostly occur in the central and northern troughs and in Capri and Eos Chasmata. The thickest exposures are in Hebes and Ophir Chasmata and parts of Candor Chasma. Elsewhere (e.g., Melas Chasma) they are thinner. Although the layers differ in colour, albedo, thickness and competence, their mineralogy is comparable.
Interior layered deposits are presumably formed by sedimentary [Nedell et al., 1987; Malin and Edgett, 2000; Rossi et al., 2007] or volcanic processes [Chapman and Tanaka, 2001; Hynek et al., 2002] early in mars history (Early Hesperian time). The sediments accumulated in troughs, and were later subject to erosion and structural displacement.
The dip of the layers in south-western Candor Chasma and their relationship with potential faulted basement blocks suggest this ILD were deposited in a low-energy sedimentary environment experiencing little tectonsim [Fueten et al., 2006]. Therefore, the ILD is assumed to be an exhumed ancient deposit. However the origin of the deposit is still under discussion and alternative theories suggest the origin may be high energy glacial, lacustrine or aeolian processes.
Chapman, M. G. and K. L. Tanaka (2001): Interior trough deposits on Mars: Subice volcanoes?, JGR, 106 (E5), 10,087-010,100. [Abstract]
Christensen, P. R., R. V. Morris, M. D. Lane, J. L. Bandfield, and M. C. Malin (2001): Global mapping of Martian hematite mineral deposits: Remnants of water-driven processes on early Mars, JGR, 106 (E10), 23,873-823,885. [Abstract]
Fueten, F., R. Stesky, P. MacKinnon, E. Hauber, K. Gwinner, F. Scholten, T. Zegers, and G. Neukum (2006): A structural study of an interior layered deposit in southwestern Candor Chasma, Valles Marineris, Mars, using high resolution stereo camera data from Mars Express, GRL, 33. [Abstract]
Gendrin, A., N. Mangold, J.-P. Bibring, Y. Langevin, B. Gondet, F. Poulet, G. Bonello, C. Quantin, J. Mustard, R. Arvidson, and S. LeMouélic (2005): Sulfates in Martian Layered Terrains: The OMEGA/Mars Express View, Science, 307, 1587-1591. [Abstract]
Hynek, B. M., R. E. Arvidson, and R. J. Phillips (2002): Geologic setting and origin of Terra Meridiani hematite deposit on Mars, JGR, 107. [Abstract]
Jaumann, R., G. Neukum, T. Behnke, T. C. Duxbury, K. Eichentopf, J. Flohrer, S. Van Gasselt, B. Giese, K. Gwinner, E. Hauber, H. Hoffmann, A. Hoffmeister, U. Köhler, K.-D. Matz, T. B. McCord, V. Mertens, J. Oberst, R. Pischel, D. Reiss, E. Ress, T. Roatsch, P. Saiger, F. Scholten, G. Schwarz, K. Stephan, M. Wählisch, and the HRSC Co-Investigator Team (2007): The high-resolution stereo camera (HRSC) experiment on Mars Express: Instrument aspects and experiment conduct from interplanetary cruise through the nominal mission, Planetary and Space Science, 55, 928-952. [Abstract]
Malin, M. C. and K.S. Edgett (2000): Sedimentary Rocks of Early Mars, Science, 290 (12), 1927-1937. [Abstract]
Mangold, N., A. Gendrin, C. Quantin, J.-P. Bibring, B. Gondet, Y. Langevin, F. Poulet, R. Arvidson, J. L. Griffes, E. Hauber, P. Masson, G. Neukum, the OMEGA, and HRSC Co- Investigator Teams (2007): An overview of the sulfates detected in the equatorial regions by the OMEGA/MEX spectrometer, ICM VII, Pasadena, CA.
Nedell, S. S., S. W. Squyres, and C. W. Andersen (1987): Origin and evolution of the layered deposits in the Valles Marineris, Mars, Icarus, 70 (3), 409-414. [Abstract]
Rossi, A. P., G. Neukum, M. Pondrelli, T. Zegers, P. Masson, E. Hauber, G. G. Ori, F. Fueten, J. Oosthoek, A. Chicarro, and B. Foing (2007): The case for large-scale spring deposits on Mars: Light-toned deposits in crater bulges, Valles Marineris and chaos, LPSC XXXVIII, Houston, TX. [Abstract]
Image source: HRSC Press Release