Late Hesperian volatile distribution within the Martian upper Crust in eastern circum Chryse, Mars
- Paper number
IAC-06-A3.P.3.13
- Author
Dr. Alexis Rodriguez, University of Tokyo, Japan
- Coauthor
Dr. Jeffrey Kargel, United States
- Coauthor
Dr. Sho Sasaki, Japan
- Year
2006
- Abstract
Our present understanding of the distribution and history of volatiles within the uncompacted zones of the Martian upper crust has been chiefly based on the study of chaotic terrains and outflow channels in circum Chryse. The interpretation that the chaotic terrains formed due to the sudden collapse and disintegration of plateau materials, and that chaos formation was associated with the release of catastrophic floods, has led to the postulation that, at least during the stage of outflow channel activity, the Martian upper crust consisted of an upper zone below freezing point, known as the cryolithosphere, and an underlying groundwater zone known as the hydrosphere [1]. Detailed morphologic and morphometric analysis of chaotic terrains by Rodriguez et al., [2] suggests that that the top zone of the Martian upper crust consists of sedimentary deposits that formed during an early period in Martian history characterized by elevated erosional/depositional rates that led to global resurfacing. Variations in rates of basin infilling and frequencies in impact during the heavy bombardment led to a random vertical distribution of buried impact craters. According to their model buried impact craters form volatile enriched crustal zones, and wherever there are clusters of proximal impact craters, superimpositions of faults peripheral to each buried impact crater form zones of extremely high subsurface permeability. They suggest that hydrothermal activity localized to these zones resulted crustal destabilization that led to surface subsidence, collapse and the release of the immense volumes of groundwater that carved the outflow channels. We find that following formation of the higher outflow channels in eastern circum Chryse, channel floor collapse resulted in the formation of secondary chaotic terrains. Their morphologic characteristics suggest that their formation did not involve rapid surface collapse and emanations of catastrophic fluids. Instead, it appears to have been related to a slower sublimation-driven post-flood collapse. We propose that the formation of secondary chaotic terrains in the higher outflow channels was related to the exposure by surface flow of cryolithospheric taliks within the upper crustal zone of Mars. REFERENCES [1] Clifford, S. M., and Parker T. J. (2001) The evolution of the Martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains, Icarus, 154, 40–79. [2] Rodriguez, J.A.P., Sasaki S., Dohm J.M., Tanaka K.L., Strom B., Kargel J., Kuzmin, R. Miyamoto H., Spray, J.G., Fairén A.G., Komatsu G., Kurita K., and Baker V. (2005) Control of impact crater fracture systems on subsurface hydrology, ground subsidence and collapse, Mars, J. Geophys. Res., 110, E06003.
- Abstract document