Neotectonics on Mars?

Mars has experienced significant tectonic activity; the majority of which appears to have taken place during the Noachian/Hesperian. There is now growing evidence that volcanic activity on Mars may have continued until very recent times. Similarly, the first evidence of very young (< 2 My) tectonics on Mars has now been identified (Spagnuolo et al., 2011; Roberts et al, 2012). We present a first compilation of possible recent (extensional) tectonic activity on Mars, far from the Tharsis volcanoes and concentrated in chasmata and chaos areas, affecting Interior Layered Deposits (ILDs), dunes and mass wasting deposits within those basins. Their morphology and morphometry have been characterized using high resolution imagery and stereo-derived topography. Several steep scarps have been identified. They border certain sections of Martian ILDs in both chasmata and chaotic terrains (e.g. Aureum, Aram). They tend to have a linear or curvilinear plan outline and they are characterized by an actual dip higher than that of the local slope. We interpret them as normal faults. These scarps are associated with major, degraded cliffs and aprons at their base. Absolute dating is difficult, but in some cases, the observable evidence suggests an age of only a few million years. Late-stage subsidence and collapse might be responsible for the initial formation and sustained activity of these faults, deforming already emplaced ILDs. We do not exclude that these structures might be the surface expressions of larger ones, potentially partially reactivated. We suggest that at least some of these faults might have been active in the last few million years and possibly still now. Whether related to regional stresses or, more likely, to some residual subsidence or collapse linked to very late-stage processes acting on Valles Marineris and Chaotic Terrains, these recent faults offer unique windows into the recent endogenic activity of Mars. Although most of the structures identified so far are located in areas that would be challenging for any lander or rover, an assessment of relatively small but possibly seismogenic faults in chasmata and chaotic terrains would have profound implications also for future exploration. Future missions addressing the state of geological activity on Mars could measure the status of some of the identified structures. References Roberts, G. P., et al. (2012), JGR, 117, E02009, doi:10.1029/2011JE003816. Spagnuolo, M., et al. (2011) EPSL, 312 (2011) 13-21. doi:10.1016/j.epsl.2011.09.052.