1. New hydrated spectral phase and stratigraphy of smectites, sulfates, and other hydrated minerals in Ius Chasma, Valles Marineris L Roach, JF Mustard, S Murchie, RE Milliken, K. Litchenberg, BL Ehlmann, J Bishop, RE Arvidson, and the CRISM Team Martian Phyllosilicates: Recorders of Aqueous Processes Oct 21, 2008

2. Hydrated silica stratigraphy Sulfate stratigraphy Nontronite and doublet stratigraphy Identification of doublet mineralogy Role of Landslides and Faulting

3. Hydrated silica stratigraphy Sulfate stratigraphy Nontronite and doublet stratigraphy Identification of doublet mineralogy Role of Landslides and Faulting

4. Hydrated silica in multiple fine layers in wallrock at head of Louros Valles and at base. Formed on plateau and washed into trough. Restricted to region near sapping channels. Hydrated silica Louros Valles headwall FRT00009998 Louros Valles mouth HRS0000B8EB Tyrrhena Mouth Headwall Opal (library)‏

5. Hydrated silica stratigraphy Sulfate stratigraphy Nontronite and doublet stratigraphy Identification of doublet mineralogy Role of Landslides and Faulting

6. Sulfates are within enclosed topographic lows – suggest they were formed by evaporation of a closed basin. First polyhydrated sulfate (PHS), then kieserite as the brine concentrated. Based on shot data, kieserite found below -4175 m, with PHS and doublet at higher elevations (-3700 to -4175 m)‏ Elevation Contour -4200 m -3500 m Sulfates Kieserite PHS Doublet

7. Hydrated silica found overlying PHS, probably sourced from sapping channel Hydrated silica layer < few m thick Thin layer of loose, non-hydrated dark material only partially fills cracks (arrow)‏ FRT00008950 and PSP_005940_1710 Hydrated silica Sulfate 150 m

8. Sulfate and hydrated silica

9. 1 2 Hydrated silica stratigraphy Sulfate stratigraphy Nontronite and doublet stratigraphy Identification of doublet mineralogy Role of Landslides and Faulting

10. 500m across 180m across Nontronite-bearing unit Polygonally fractured but no layering or relief exposed. Doublet material-bearing unit Nontronite in thin layers overlain by doublet material. In one case doublet unconformably drapes nontronite. Layered Smectite clays Kieserite PHS Doublet

11. HiRISEPSP_006718 colorized with FRT000085A4 (RGB: 2.5, 1.5, 1.08 μm)

12. Doublet unit is brighter, more fractured, and clearly overlies smectite (smoother layered material). Window into layered smectite through doublet material Doublet unit drapes previously eroded smectite layered unit Layered Smectite clays

13. FRTBFE4FRT9B27FRTA202FRT823A Layered Smectite clays Nontronite (green) and doublet (blue)‏

14. FRT00009B27, looking S Nontronite (green) at higher elevation than doublet. Adjacent obs shows doublet material overlying nontronite.

15. Doublet spectral type Some variability in relative strength of 2.21 and 2.27 um bands

16. Doublet spectral type No library spectra are perfect matches

17. Hydrated silica stratigraphy Sulfate stratigraphy Nontronite and doublet stratigraphy Identification of doublet mineralogy Role of Landslides and Faulting

18. Multiple landslide events range from “dry” (leftmost, with no mineral signatures) to “wet” (rightmost) and nontronite and doublet material in breccia. Central landslide is not yet determined. Landslides similarly fluidized. Leftmost landslide material overruns doublet breccia material, possibly from earlier landslide Nontronite and doublet material not localized to specific breccia blocks Landslides of hydrated material Next slide Smectite and Doublet Doublet

19. FRT27E2FRTA396 FRT905B Distinctive variegated color HiRISE next page Doublet-only material: located in older landslides or in basement breccia? Landslides of hydrated material

20. PSP_006652_1725, overlapping FRTA396 Folds, fractures, and megabreccia blocks. All with 1.4, 1.9, 2.22, and 2.27 μm abs. Images ~250 m across Landslides of hydrated material

21. Interpreted Ius Chasma Stratigraphy –Sulfates form by closed evaporating basin without recharge –Smectite in both breccia and matrix of landslides – Noachian megabreccia altered by hydrothermal processes? Could non-hydrated mineral-bearing landslides be unaltered Hesperian material? –Smectites in layers in local lows – fluvial deposition? Altered ash fall? –Doublet unit unconformably overlies layered smectites, evidence of change in aqueous geochemistry? Need to resolve doublet mineralogy –Doublet also found alone or mixed with smectites in landslides. Perhaps doublet formed by second period of aqueous alteration on trough floor. Would explain both landslides with and without smectite. –Hydrated silica most recent alteration mineral. Transported short distances by sapping channel flow. Sourced from top of wall rock