NASA Astrobiology Institute (NAI)

1. Early oceans on Mars

   Project Investigators:

   Other Project Members

   Amy Daradich (No Role Selected)

   Michael Manga (No Role Selected)

   Jerry Mitorvica (No Role Selected)

   Taylor Perron (No Role Selected)

   edwin kite (Doctoral Student)

   Summary

   We investigate the possible origin and fate of oceans early in Martian history.

   Astrobiology Roadmap Objectives:

   • Objective 1.1: Models of formation and evolution of habitable planets
   • Objective 2.1: Mars exploration

   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.

   
   

   Possible shear zone formed by thermochemical convection in ocean-deposited evaporites.

Publications

Daradich, A.  (2008).  Equilibrium rotational stability and figure of Mars.  Icarus, 194:463-475.

Kite, E.S.  (submitted).  True polar wander driven by late-stage volcanism and the distribution of paleopolar deposits on Mars.  Geophysical Research.