Science Seminars

1/21/2010 – Characteristics of the Martian Cryolithhosphere in Zones of Outflow Channel Occurrence

Speaker: Alexis Palmero Rodriguez (Planetary Science Institute, Texas)
Date: Thursday, Jan 21, 2010
Time: 4:00pm
Location: Duane

Seminar Abstract:

Previous workers have suggested that chaotic terrain formation on Mars occurred in zones of elevated hydraulic head within a global hydrosphere.Our results indicate that chaotic terrain formation in the region of southern circum-Chryse may have resulted from the disruption of thick sedimentary deposits that contained large numbers of buried impact craters. The presented model suggests that these craters were surrounded by dense fracture systems formed during the impact events, and that both the impact crater cavities and their peripheral fractures may form zones of elevated concentrations of volatiles within the cryolithosphere. Overlapping systems of subsurface fractures and craters would have provided extensive systems of highly permeable upper crustal materials enabling distal groundwater migration into the chaotic terrains and the outflow channels, and accounting for the observed patterns of subsidence that extend beyond the margins of chaotic terrains. In addition, non-emergent thrust faults underlying wrinkle ridges may have also been zones of high permeability and aquifer formation. Formation of subsurface cavities filled with volatiles produced by melting of the permafrost and density differentiation (lithics settling relative to the volatile phase) may have also contributed to increasing the degree of subsurface interconnectivity. In summary, our work regarding the Martian cryolithosphere-hydrosphere system is indicative of an important control of tectonic fabrics on the patterns and magnitude of groundwater migration and emergence. In addition, volatile distribution appears highly heterogeneous. These results are consistent with more recent work that SUPPORT a compartmented hydrospheric system on Mars (Andrews-Hanna et al., 2007; Coleman et al., 2007; Harrison and Grimm, 2009).