DEUCALIONIS-REGIO, MARS - EVIDENCE FOR A NEW-TYPE OF IMMOBILE WEATHERED SOIL UNIT

A small equatorial region south of Sinus Meridiani, Deucalionis Regio, has been found spectrally distinct from other regions as seen in a hi gh spectral resolution telescopic image of Mars. Interpretations from a variety of other observations, including infrared radiometric data, historical occurrences of localized dust storms, and general circulati on wind modeling, also suggest that the surface of Deucalionis Regio h as properties that are different than those of nearby regions, Arabia, Acidalia, Sinus Meridiani, and Oxia, in terms of expression of color, crystalline hematite content, and perhaps pyroxene abundance and mine ralogy. The thermophysical and aeolian observations indicate that the soils in Deucalionis Regio are relatively immobile, despite the likely occurrence of winds strong enough to move unconsolidated materials. W e propose that the soils in this region are indurated or crusted. We p redict that a Mars Observer-class thermal emission spectrometer and ga mma ray spectrometer will show the presence of crust-forming minerals and elements in the soils of this region. The spatial correlation betw een areas that have been previously proposed to be regional exposures of crust, and areas that are spectrally similar to Deucalionis Regio, may suggest a possible genetic relationship between the composition an d the physical properties. (C) 1996 Academic Press, Inc.