Grant, John A. and Wilson, Sharon A. and Dobrea, Eldar Noe and Fergason, Robin L. and Griffes, Jennifer L. and Moore, Jeffery M. and Howard, Alan D. (2010) HiRISE views enigmatic deposits in the Sirenum Fossae region of Mars. Icarus, 205 (1). pp. 53-63. ISSN 0019-1035 http://resolver.caltech.edu/CaltechAUTHORS:20100217-090352028
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HiRISE images together with other recent orbital data from Mars define new characteristics of enigmatic Hesperian-aged deposits in Sirenum Fossae that are mostly 100–200 m thick, drape kilometers of relief, and often display generally low relief surfaces. New characteristics of the deposits, previously mapped as the “Electris deposits,” include local detection of meter-scale beds that show truncating relationships, a generally light-toned nature, and a variably blocky, weakly indurated appearance. Boulders shed by erosion of the deposits are readily broken down and contribute little to talus. Thermal inertia values for the deposits are ~200 J m^(−2) K^(−1) s^(−1/2) and they may incorporate hydrated minerals derived from weathering of basalt. The deposits do not contain anomalous amounts of water or water ice. Deflation may dominate degradation of the deposits over time and points to an inventory of fine-grained sediment. Together with constraints imposed by the regional setting on formation processes, these newly resolved characteristics are most consistent with an eolian origin as a loess-like deposit comprised of redistributed and somewhat altered volcanic ash. Constituent sediments may be derived from airfall ash deposits in the Tharsis region. An origin directly related to airfall ash or similar volcanic materials is less probable and emplacement by alluvial/fluvial, impact, lacustrine, or relict polar processes is even less likely.
|Additional Information:||© 2009 Published by Elsevier Inc. Received 7 November 2008; revised 23 April 2009; accepted 24 April 2009. Available online 9 May 2009. We thank the people at the University of Arizona, Ball Aerospace, the Jet Propulsion Laboratory, and Lockheed Martin that built and operate the HiRISE camera and the Mars Reconnaissance Orbiter Spacecraft. Reviews by Kevin Williams, Ken Herkenhoff, and an anonymous reviewer improved the manuscript. This work was supported by NASA.|
|Subject Keywords:||Mars; Geological processes|
|Official Citation:||John A. Grant, Sharon A. Wilson, Eldar Noe Dobrea, Robin L. Fergason, Jennifer L. Griffes, Jeffery M. Moore, Alan D. Howard, HiRISE views enigmatic deposits in the Sirenum Fossae region of Mars, Icarus, Volume 205, Issue 1, MRO/HiRISE Studies of Mars, January 2010, Pages 53-63, ISSN 0019-1035, DOI: 10.1016/j.icarus.2009.04.009. (http://www.sciencedirect.com/science/article/B6WGF-4W7YXX4-2/2/3ecd139a4897df696d162f0f016c4c28)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||19 Feb 2010 18:17|
|Last Modified:||26 Dec 2012 11:46|
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