Wray, J. J. and Milliken, R. E. and Dundas, C. M. and Swayze, G. A. and Andrews-Hanna, J. C. and Baldridge, A. M. and Chojnacki, M. and Bishop, J. L. and Ehlmann, B. L. and Murchie, S. L. and Clark, R. N. and Seelos, F. P. and Tornabene, L. L. and Squyres, S. W. (2011) Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars. Journal of Geophysical Research E, 116 . Art. No. E01001. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:20121016-103332073
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Columbus crater in the Terra Sirenum region of the Martian southern highlands contains light-toned layered deposits with interbedded sulfate and phyllosilicate minerals, a rare occurrence on Mars. Here we investigate in detail the morphology, thermophysical properties, mineralogy, and stratigraphy of these deposits; explore their regional context; and interpret the crater's aqueous history. Hydrated mineral-bearing deposits occupy a discrete ring around the walls of Columbus crater and are also exposed beneath younger materials, possibly lava flows, on its floor. Widespread minerals identified in the crater include gypsum, polyhydrated and monohydrated Mg/Fe-sulfates, and kaolinite; localized deposits consistent with montmorillonite, Fe/Mg-phyllosilicates, jarosite, alunite, and crystalline ferric oxide or hydroxide are also detected. Thermal emission spectra suggest abundances of these minerals in the tens of percent range. Other craters in northwest Terra Sirenum also contain layered deposits and Al/Fe/Mg-phyllosilicates, but sulfates have so far been found only in Columbus and Cross craters. The region's intercrater plains contain scattered exposures of Al-phyllosilicates and one isolated mound with opaline silica, in addition to more common Fe/Mg-phyllosilicates with chlorides. A Late Noachian age is estimated for the aqueous deposits in Columbus, coinciding with a period of inferred groundwater upwelling and evaporation, which (according to model results reported here) could have formed evaporites in Columbus and other craters in Terra Sirenum. Hypotheses for the origin of these deposits include groundwater cementation of crater-filling sediments and/or direct precipitation from subaerial springs or in a deep (∼900 m) paleolake. Especially under the deep lake scenario, which we prefer, chemical gradients in Columbus crater may have created a habitable environment at this location on early Mars.
|Additional Information:||© 2011 American Geophysical Union. Received 12 July 2010; accepted 3 November 2010; published 5 January 2011. We thank S. Mattson and A. Dumke for their efforts producing HiRISE and HRSC DEMs, respectively. Early reviews by J. K. Crowley, G. A. Desborough, and S. A. Wilson Purdy as well as discussions with J. F. Mustard, M. P. Golombek, N. A. Cabrol, J. A. Grant, D. J. Des Marais, V. F. Chevrier, T. S. Altheide, and S. Karunatillake improved the paper. We thank R. P. Irwin III and an anonymous reviewer for their thorough attention to the manuscript. J.J.W. thanks the Fannie & John Hertz Foundation and the NSF Graduate Research Fellowship for support. We thank the HiRISE and CRISM science and operations teams for acquiring the data most critical to our observations and interpretations.|
|Subject Keywords:||Mars; crater; paleolake; sulfate; phyllosilicate; astrobiology|
|Official Citation:||Wray, J. J., et al. (2011), Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars, J. Geophys. Res., 116, E01001, doi:10.1029/2010JE003694.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||16 Oct 2012 18:03|
|Last Modified:||27 Dec 2012 02:52|
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