Distribution, Morphology, and Origin of Layered Deposits within Schiaparelli Basin, Mars

Article · September 2002with 12 Reads
Abstract
Schiaparelli basin is an ancient 470-km impact structure found in the eastern Terra Meridiani region of Mars. Observed along the interior margins of this basin are sequences of layered deposits that occur within material mapped as smooth plains. In places, over a dozen distinct layers are identified on high resolution Global Surveyor MOC images, with individual layer thicknesses ranging between 10 - 25 m as determined from MOLA data. Although these sediments may have been emplaced as an air fall deposit (i.e., volcanic ash or aeolian dust) [e.g., 1], evidence suggest that such layers may have been deposited in an aqueous environment - one characterized by alternating periods of deposition and non-deposition [2]. Since Schiaparelli is a closed basin, it could have served as a lake reservoir during early Martian history when environmental conditions were suitable for supporting seas of water [3]. If this were the case, then layered sediments may have formed insitu. Such a lacustrine setting could have produced the observed layering by way of the deposition of limestone. Although carbonate material may have been deposited through a purely chemical process, its presence is intriguing for its paleobiological implications since, as on Earth, the accretion of shells and other hard parts of marine organisms produce some forms of this rock. Ongoing research includes the analyses of Odyssey THEMIS data, in conjunction with morphologic evidence, in an attempt to detect the presence of carbonate deposits within the Schiaparelli basin. References: [1] B. A. Hynek et al. (2002), LPSC, 33, 1408. [2] M. C. Malin and K. S. Edgett (2000), Science, 290, 1927-1936. [3] N. A. Cabrol and E. A. Grin (2001) Icarus, 149, 291-328.

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  • ... Tilted layering in the fill could be interpreted as aeolian sediments while parallel layers, if observed, can be associated with a fluvial filling process. Such sedimentation is already observed in high-resolution MOC images in several mid-latitude Martian craters as previously mentioned for the impact crater (located at 0.9°S, 346.2°W) in the northwestern Schiaparelli Basin [Crane and Albin; 2002], ...
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    We report results from a field survey performed on a recently discovered impact field in the southwestern Egyptian desert, using a 270 MHz Ground-Penetrating Radar (GPR). This hyperarid region has significant similarities to the Martian heavily eroded mid-latitude cratered terrains in terms of crater density, size, and geomorphology. Profiles across small-buried craters revealed a coherent sequence of tilted layers constituting the cratonic infill resulting from aeolian deposits. In the intercrater areas the radargram revealed a poorly-defined subsurface stratigraphy and the presence of shallow structural elements associated with potential evidences of the consequences of the shock effects, i.e., faulting, fractures, and chaotic bedrock. The radar-penetration depth varied from 2 to 15 m, depending mainly on the amplitude of the volume and multiple scattering in the subsurface, caused by fractures and debris created by the impacts. We conclude that mid-frequency GPR onboard future Martian rovers can successfully perform similar structural mapping.
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