ESA Mars Express - Deep faults and disrupted crater at Acheron Fossae

This is an image taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express of the Acheron Fossae region, an area of intensive tectonic (continental ‘plate’) activity in the past.

Other images of this region are available here at ESA website.

Acheron Fossae marks the northern edge of the Tharsis plateau. It is part of a network of extensional fractures that radiates outward from their central focus in the Tharsis ‘bulge’, a huge area of regional uplift where intensive volcanic activity occurred.

Mars Tharsis Plateau

These curved ‘faults’ were caused in the process of this uplift: cracks in the crust formed when the hot material rising from deep in the mantle of Mars pushed the overlying ‘elastic’ lithosphere (surface layers of rock) upward.

When the distorting tensions became too strong, the brittle crust on top of the lithosphere broke along zones of weakness.

The image, from orbit 37, are dominated by these curved features, showing a highly fractured, faulted and deformed area in the central part of the Acheron Fossae.

The feature is situated at approximately 35º-40º North and 220º-230º East, about 1000 kms north of the large Olympus Mons volcano.


Credits: ESA/DLR/FU (G. Neukum)

Mysterious Streaks in the Acheron Fossae region of Mars.

This observation shows a portion of the wall (light-toned material) and floor of a trough in the Acheron Fossae region of Mars.

Many dark and light-toned slope streaks are visible on the wall of the trough surrounded by dunes.

Slope streak formation is among the few known processes currently active on Mars.

While the mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material.

Some of the slope streaks show evidence that downslope movement is being diverted around obstacles, such as large boulders, and a few appear to originate at boulders or clumps of rocky material.

These slope streaks, as well as others on the planet, do not have deposits of displaced material at their downslope ends.

The darkest slope streaks are youngest and can be seen to cross cut and lie on top of the older and lighter-toned streaks.

The lighter-toned streaks are believed to be dark streaks that are lightening with time as new dust is deposited on their surface.

Image: NASA/JPL/University of Arizona