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Evidence for ice flow prior to trough formation in the martian north polar layered deposits

Winebrenner, Dale P. and Koutnik, Michelle R. and Waddington, Edwin D. and Pathare, Asmin V. and Murray, Bruce C. and Byrne, Shane and Bamber, Jonathan L. (2008) Evidence for ice flow prior to trough formation in the martian north polar layered deposits. Icarus, 195 (1). pp. 90-105. ISSN 0019-1035. doi:10.1016/j.icarus.2007.11.030.

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The relative importance of surface mass fluxes and ice flow in shaping the north polar layered deposits (NPLD), now or in the past, remains a fundamental and open question. Motivated by observation of an apparent ice divide on Gemina Lingula (also known as Titania Lobe), we propose a two-stage evolution leading to the present-day topography on that lobe of the NPLD. Ice flow approximately balances surface mass fluxes in the first stage, but in the second stage ice flow has minimal influence and topography is modified predominantly by the formation of troughs. We focus here on evidence for the first stage, by testing the fit of topography between troughs to an ice-flow model. We find that independent model fits on distinct flow paths closely match inter-trough topography, uniformly over a broad region on Gemina Lingula, with mutually consistent and physically reasonable fitting parameters. However, our model requires ice to occupy and flow in spaces where troughs currently incise the ice. We therefore infer that the troughs (and the distribution of mass balance that caused them) post-date deposition of the inter-trough material and its modification by flow. Because trough formation has apparently altered inter-trough topography very little, we infer that trough formation must have been rapid in comparison to the (still unknown) time-scale of flow since troughs began to form. We view the evidence for past flow as strong, but we do not think that topographic evidence alone can be conclusive. Observations of englacial stratigraphy using orbital sounding radars will yield conclusive tests of our inferred mechanism for the formation of inter-trough topography.

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Additional Information:© 2008 Elsevier Inc. Received 27 August 2007; revised 29 October 2007. Available online 12 January 2008. We thank I.R. Joughin for helpful conversations on flow-line delineation and for providing to us his gradient-finding routine. This work was supported by NASA grant NNX06AD99G and NSF grant OPP 0440666.
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NSFOPP 0440666
Subject Keywords:Marspolar caps; Geophysics; Ices
Issue or Number:1
Record Number:CaltechAUTHORS:20140409-152845292
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Official Citation:Dale P. Winebrenner, Michelle R. Koutnik, Edwin D. Waddington, Asmin V. Pathare, Bruce C. Murray, Shane Byrne, Jonathan L. Bamber, Evidence for ice flow prior to trough formation in the martian north polar layered deposits, Icarus, Volume 195, Issue 1, May 2008, Pages 90-105, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44838
Deposited By: Ruth Sustaita
Deposited On:09 Apr 2014 22:44
Last Modified:10 Nov 2021 16:56

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