Grady, M.

Nussbaumer, J.

English

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Open Research OnlineThe Open University’s repository of research publicationsand other research outputsSedimentation in Meridiani Terrae, Mars, owing tomagma-ice interaction when Tharsis arose?Conference or Workshop ItemHow to cite:Nussbaumer, J. and Grady, M. (2004). Sedimentation in Meridiani Terrae, Mars, owing to magma-ice interactionwhen Tharsis arose? In: 67th Annual Meeting of the Meteoritical Society, 2-6 Aug 2004, Rio de Janeiro, Brazil.For guidance on citations see FAQs.c© [not recorded]Version: [not recorded]Link(s) to article on publisher’s website:http://www.lpi.usra.edu/meetings/metsoc2004/pdf/5155.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukSEDIMENTATION IN MERIDIANI TERRAE, MARS, OWING TO MAGMA-ICE INTERACTION WHEN THARSIS AROSE? J. Nussbaumer and M. Grady, Department of Mineralogy, Natu-ral History Museum, London, UK, E-mail: jurn@nhm.ac.uk.   Introduction: Cold temperatures on Mars [1] and a thin atmos-phere prevent the occurrence of water in liquid form on the planet. However, sedimentary rocks at Meridiani Terrae show aqueous sedimentation. Catastrophic outgassing due to the Thar-sis rise would result in increasing temperature and pressure, ena-bling water to exist on the surface for short periods of time. Magma–ice interactions during intrusive events that correspond to peak periods of Tharsis volcanic activity have been proposed as possible origins of  surface materials in Xanthe, Margaritifer, and Meridiani Terrae [2]. New images from the Opportunity landing site show what appear characteristic of sedimentary se-quences including gradation and cross-bedding. Turbulent flow of sediment-laden water deposits grains in a graded sequence, such as is common in turbidites. Jokulhlaup deposits (sediments from subglacial outburst floods resulting from volcanic activity) in Iceland also show graded deposition [3], superposed by cross bedding structures, reflecting deposition during both the rising and falling limbs of the flood hydrograph.  Fig. 1: Graded and cross-bedded sedimentary structures (adapted from Maizels 1997), and microscopic image of graded rocks from the  Opportunity landing site, both are sequences thought to have been deposited by a waning, low density turbidity current in shallow lacustrine environment (image courtesy NASA/JPL/Cornell). Conclusions and future work: Widespread changes in vol-canic activity, atmospheric density, and water vapour triggered by Tharsis volcanoes should leave their footprints in martian rocks. At present, the only samples of the martian surface that we have in our collections are martian meteorites. Although they are all igneous rocks, they do contain pockets of melts produced by aqueous alteration [4]. We intend to investigate potential coorela-tions in the timing and extent of activity by means of  laboratory measurements, especially IR-spectroscopy. References: [1] Gaidos, E., and G. Marion, 2003, J.Geophys.Res., 108 (E6). [2] Chapman M. and Tanaka K., 2001, Icarus 155, 324–339 [3] Maizels, J., 1997, Quaternary. Science Reviews, Vol. 16, pp. 793-819. [4] Bridges, J. et al., 2001, Space Sci. Rev., 365-392.   67th Annual Meteoritical Society Meeting (2004) 5155.pdf

Sedimentation in Meridiani Terrae, Mars, owing to magma-ice interaction when Tharsis arose?

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Sedimentation in Meridiani Terrae, Mars, owing to magma-ice interaction when Tharsis arose?

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