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Spectrally distinct ejecta in Syrtis Major, Mars: Evidence for environmental change at the Hesperian-Amazonian boundary

Skok, John R. and Mustard, John F. and Murchie, Scott L. and Wyatt, Michael B. and Ehlmann, Bethany L. (2010) Spectrally distinct ejecta in Syrtis Major, Mars: Evidence for environmental change at the Hesperian-Amazonian boundary. Journal of Geophysical Research E, 115 . Art. No. E00D14. ISSN 0148-0227.

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Analysis of visible and near-infrared (VNIR) imaging spectrometer data of the Syrtis Major volcanic complex on Mars shows spectrally distinct ejecta (SDE) around a subset of the region's impact craters. We explore the nature of this spectral difference with the intention of constraining the physical cause of the distinction and the significance of their near random spatial distribution. Crater counting performed by Baratoux et al. (2007) indicated that the craters with SDE are systematically younger than craters without SDE. Extensive crater counts of the craters with SDE show that they fit a consistent Hartmann (2005) isochron indicting that they represent temporally continuous population. This population was dated near 2 Ga, consistent with the counts of Baratoux et al. (2007). This modeled age corresponds to just after the Hesperian-Amazonian boundary, indicating that it may be related to a global event. We explore possible explanations for the lack of SDE around older craters, including atmospheric changes, significant but brief regional emplacement of materials, and volcanic activity. We conclude that the preferred explanation is that the SDE represent the true composition of the Syrtis Major volcanics and that surfaces older than 2 Ga were altered by interactions with water vapor or volcanic gases under different Hesperian climatic and atmospheric conditions leading to all craters formed after this alteration event to display SDE.

Item Type:Article
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URLURL TypeDescription
Murchie, Scott L.0000-0002-1616-8751
Ehlmann, Bethany L.0000-0002-2745-3240
Additional Information:© 2010 American Geophysical Union. Received 23 January 2009; accepted 23 September 2009; published 27 February 2010. The work has benefited greatly from the technical assistance and scientific guidance of Leah Roach, the crater counting advice from Caleb Fassett, and the insightful comments of an anonymous reviewer. Additional thanks to the OMEGA and CRISM teams for data acquisition and processing. We gratefully acknowledge NASA’s support for the CRISM investigation through the Mars Reconnaissance Orbiter mission. This works is supported by subcontract JHAP852950 from the Johns Hopkins University Applied Physics Laboratory.
Funding AgencyGrant Number
NASA Mars Reconnaissance Orbiter missionUNSPECIFIED
Johns Hopkins University Applied Physics LaboratoryJHAP852950
Subject Keywords:remote sensing; surface coating
Record Number:CaltechAUTHORS:20121016-075223105
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Official Citation: Skok, J. R., J. F. Mustard, S. L. Murchie, M. B. Wyatt, and B. L. Ehlmann (2010), Spectrally distinct ejecta in Syrtis Major, Mars: Evidence for environmental change at the Hesperian-Amazonian boundary, J. Geophys. Res., 115, E00D14, doi:10.1029/2009JE003338.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34908
Deposited By: Ruth Sustaita
Deposited On:16 Oct 2012 15:09
Last Modified:09 Mar 2020 13:19

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