Figure 1 A: Valles Marineris showing location of Hebes Chasma. B: Mars Orbiter Laser Altimeter shaded relief map of Hebes Chasma showing locations of closed depressions, pits (P), and troughs (T) on chasma floor. C: Visible mosaic of Hebes Chasma. Mars Express High Resolution Stereo Camera. N

Figure 1. (A) Valles Marineris region showing the location of Hebes Chasma and nearby features. Mars Orbiter Laser Altimeter data. (B) Visible mosaic of Hebes Chasma showing informal place names used in this paper. Mars Express High Resolution Stereo Camera.

Figure 3 A: Oblique view of east Hebes Chasma and North Pit. Mars Express High Resolution Stereo Camera (HRSC); vertical exaggeration = 2×. 1—Northeast Flow; 2—Tongue; 3—East Pit; 4—Swale. B: Detail of headwall of Northeast Flow. Plains surface (5) and Upper Hebes Formation (UHF) (6) were dropped

Figure 13. Geologic map of Hebes Chasma produced by photogeologic interpretation. Table 3 provides a detailed legend.

Figure 14. Nadir view of Hebes Chasma showing the location of illustrations. Visible mosaic is from Mars Express High Resolution Stereo Camera.

TABLE 3. DESCRIPTIVE LEGEND FOR GEOLOGIC MAP UNITS OF HEBES CHASMA

Figure 15. The Swale at the east end of Hebes Chasma. (A) Oblique view to the northwest (no vertical exaggeration). Mars Express High Resolution Stereo Camera. (B) Nadir view with spot heights showing the ∼600 m relief of the sag between bounding fossae. Mars Odyssey Mission, THEMIS V18276001

Figure 16. (A) Big Slab in the north wall of Hebes Chasma in an oblique view to the northwest. Eye altitude is 11 km; ∼2× vertical exaggeration. Image via Google Earth from NASA/USGS/ESA/DLR/FU Berlin (G. Neukum). (B) Island Block near the southeast wall of Hebes Chasma in an oblique view

Figure 18. Map of Hebes Chasma showing the larger flows, diapirs, and pits. Large flows are sutured head to head in the South Basin and in the East Pit, as in the model. Background image is a visible mosaic from Mars Express High Resolution Stereo Camera.

Figure 19. (A) Mini-Mensa, an inferred emergent diapir in Hebes Chasma. Figure 14 shows location. (B) Jahangir Khan diapir composed of Upper Jurassic salt in the North Kerman (Ravar) Basin, Iran. Diapir is 1.2 km long and 0.9 km wide. View is to southeast; eye altitude is 2.2 km; no vertical

Figure 21. The Tongue in the eastern half of Hebes Chasma in an oblique view to the south. Eye altitude is 61 km; 2× vertical exaggeration. Image via Google Earth from ESA/DLR/FU Berlin (G. Neukum). Figure 14 shows location.

Figure 23. (A) Deep-sourced flows from the north wall of Hebes Chasma into the North Pit. The terminus of the flows (solid line) is inferred to mark the former drainage axis; the present-day trench (dashed line) is inferred to mark the final drainage axis. Oblique view to the west; eye altitude

Figure 26. (A) Present-day N-S cross section across Hebes Chasma and mensa. Location shown in Figure 14 . (B) The same section restored to a stage after the chasma subsidence had mostly ended, after the drains were clogged and overrun by flows from the base of the mensa and chasma walls. (C

Figure 5 Vertical view of evolving laboratory model of Hebes Chasma. A: Early stage of evacuation. B: Intermediate stage. C: Advanced stage. 1—graben; 2—swale; 3—thrust along trench axis; 4—inward-tilted slabs; 5—pit; 6—Hebes Mensa; 7—radial faulting in diapir roof; 8—downfaulted plains surface

Figure 6 Map of kieserite in Hebes Chasma measured by OMEGA (see text) near-infrared spectroscopy. Mars Express High Resolution Stereo Camera visible mosaic.

Fig. 3 (a) Hebes Chasma wall rock landslide complex (Slide 2) and ILD landslide (Slide 3). Arrows show movement directions for respective landslides. Image modified from MOC Image R0301338. Illumination from left.

Figure 3. Mechanical stratigraphy and qualitative strength profile of the three model layers and equivalent geologic units in Hebes Chasma. Figure 13 and Table 3 summarize Hebes geologic data.

Figure 2 A: Resistant layers of Upper Hebes Formation (UHF) on northeast rim of Hebes Chasma above talus slope of Lower Hebes Formation (LHF). UHF is not disturbed by impact crater on plains in upper right, implying post-impact formation by diagenesis. CTX (Mars Reconnaissance Orbiter Context