¹Alicia Noel,¹Janice L. Bishop,^2,3Muna Al-Samir,²Christoph Gross,
⁵Jessica Flahaut,^2,4Patrick C. McGuire,⁶Catherine M. Weitz,⁴Frank Seelos,⁴Scott Murchie

¹Carl Sagan Center, The SETI Institute, Mountain View, CA 94043, USA
²Planetary Science and Remote Sensing Group, Institute of Geosciences, Freie Universität Berlin, 12249 Berlin, Germany
³DLR, Institute of Planetary Research, Berlin, Germany
⁴Applied Physics Laboratory, Laurel, MD 20723, USA
⁵Earth and Life Sciences, Vrije Universiteit (VU) Amsterdam, Amsterdam, Netherlands
⁶Planetary Sciences Institute, Tucson, AZ 85721, USA

Juventae Chasma is a deep depression located north of Valles Marineris on Mars, with four bright mounds or light-toned interior layered deposits (ILDs) extending upwards from the Canyon floor. We present here the results of long-term imaging of Juventae Chasma including mounds A, B, C, and D using multiple datasets. Monohydrated sulfates (MHS) were deposited first on the canyon floor, followed by polyhydrated sulfates (PHS). The upper PHS-dominated units are largely eroded away at Juventae Chasma, but this material is still present in significant abundance at mound B. PHS are observed mixed with MHS in some areas of mounds A and C. Terraces are observed at the upper elevations of mound B that contain PHS at the steeper slopes and appear to be covered with dust on the horizontal surfaces. Current analyses of the MHS-rich unit indicate that kieserite (MgSO4⋅H2O) is the primary sulfate component, rather than szomolnokite (FeSO4⋅H2O) as previously thought. Formation of kieserite at Juventae Chasma likely required temperatures in the 150–200 °C range. Geochemical modeling is most consistent with dissolution of mafic materials followed by precipitation of kieserite from solution. The dust exhibits ferric signatures and the sand is largely mafic material. Outcrops of olivine- and pyroxene-bearing rocks are best observed along the base of mound C and in the chaotic terrain surrounding mound D. This study summarizes the current understanding of Juventae Chasma and its ILDs using HRSC, HiRISE and CTX data, an expanded laboratory spectral library, and the latest calibrations available for CRISM.

Reference
Noel A, Bishop JL, Al-Samir M, Gross C, Flahaut J, McGuire PC, Weitz CM, Seelos F, Murchie S (2014) Mineralogy, morphology and stratigraphy of the light-toned interior layered deposits at Juventae Chasma. Icarus (in Press)
Link to Article [DOI: 10.1016/j.icarus.2014.09.033]

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