Emplacement of Lobate Rock-Glacier Landforms and Landscape Modification

• Main Authors: Mareotis Fossae Mars, S. Van Gasselt, E. Hauber, G. Neukum
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: climate; Mars; periglacial; planetary permafrost; rock glaciers; Ice; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.622.7369; http://elib.dlr.de/55901/1/Van_Gasselt_et_al.Tempe_LDA.NICOP_2008.pdf

The so-called fretted terrain at the Martian dichotomy boundary exhibits a variety of creep-related morphologies generally known as lobate debris aprons and lineated valley fills. These features usually occur along troughs and circumferentially to remnant massifs. We here report on investigations of debris aprons and adjacent terrain in the Tempe Terra/Mareotis Fossae region and provide observational evidence for several phases and mechanisms of debris supply at remnant massifs comprising rock fall and large-scale landsliding and terminating with deposition and disintegration of a widespread surficial mantling deposit. The mantling deposit disintegrates by processes similar to thermokarstic degradation as indicated by heavily dissected areas and characteristic shallow and aligned circular depressions. Comparisons of theoretically derived cross-section profiles to topographic measurements along and across lineated-valley fill units, as well as lobate debris aprons, provide additional clues that such creep-related landforms are currently degrading,. It is also shown that a considerable volume of debris/ice is transported along the intra-highland valleys. Such processes might even be active today, as geomorphologic features appear pristine, and crater-size frequency measurements yield ages in the range of 50–100 Ma only. Such observations confirm modeling results of the stability of ground ice on Mars. Various phases of emplacement and degradation confirm theories about cyclic re-deposition of volatiles caused by the changes of the configuration of orbital parameters of Mars.