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Project Progress

In the previous year we suggested that the signature of large past oceans on Mars is preserved as deformed shorelines following an episode of true polar wander (Perron et al., 2007). We investigated the relic signature of this possible polar wander in the present day Martian gravity field. We are unable to rule out the possibility of significant polar wander (Daradich et al., 2008).

Water-lain sediments associated with the proposed northern ocean on Mars
have not been found. In the west of the Hellas basin, however, wind
erosion has exposed deep-lying, deformed layered terrain. Earlier work
based largely on Viking data identified Hellas as a candidate ocean, and
these deformed layers may be its sedimentary record. But spectroscopic
confirmation is lacking, in part because Hellas is coated by bright,
anhydrous dust.

Thick evaporite deposits on Early Mars would have been unstable to thermal
convection. The deformed layered terrain shows a kilometer-scale cellular
pattern, consistent with both thermal convection and compositional
convection. We have assembled a GIS of the Western Hellas region to map
and understand stratigraphic relationships. We are working to quantify the observed deformation, and relate these measurements to 2D numerical simulations of diapirism and convection within sedimentary deposits. Our short-term objective is to determine the thickness, and constrain the effective viscosity, of the deformed layered terrain.

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