8/3/2019 Current State and Disintegration of Rock-Glacier Landforms in Tempe Terra Mars - S Van Gasselt Et Al 2007

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European Space Agency

European Mars Science and Exploration Conference: Mars Express & ExoMars

ESTEC, Noordwijk, The Netherlands, 12 - 16 November, 2007

Current State and Disintegration of Rock-Glacier Landforms in Tempe Terra, Mars S. van Gasselt1, E.Hauber, G. Neukum

1. 1Institute of Geological Scienes, Planetary Sciences and Remote Sensing. 2German Aerospace Center,

Institute of Planetary Research. stephan.vangasselt@fu-berlin.de

Abstract: The fretted terrain at the Martian

dichotomy boundary exhibits a variety of creep-related morphologies generally known as lobate

debris aprons and lineated valley fills [1-5]. We here

investigate debris aprons and adjacent terrain in the

Tempe Terra/Mareotis Fossae region (270-294E,

46-54N) and provide observational evidence for

several stages and mechanisms of debris supply at

remnant massifs, i.e., rock fall and landsliding in a

sequence with (cyclic) 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. Correlations ofgeomorphometric key parameters in a global context

show that the Tempe Terra/Mareotis Fossae debris

aprons are comparable to other characteristic

locations of debris aprons on Mars. The values for

these key parameters do not show any significant

dependencies on geographic locations (e.g.,

latitudes), suggesting that an equilibrium state of

debris advance and deformation has been reached

globally before disintegration processes initiated.

The latest phase of apron deformation has been

active in a geologically recent time as

geomorphologic features appear pristine and crater

size-frequency measurements on selected apronsyield ages in the range of 50-100 Ma only and

would support the idea of climatically-driven

landform degradation at Martian mid-latitudes.

Degradation of surfaces is also confirmed by

observations of theoretically derived cross-profiles

of debris aprons and lineated valley fill units. Both

creep-related landforms show an unsatisfactory fit to

the model-curve. This divergence might either be

caused by limitations in the flow relation used for

the model or by the eroded state of these landforms,

similar to what is known from terrestrial rock-

glacier research [e.g., 6-7].

References: [1] Sharp, J. Geophys. Res., 78, pp.

4073, 1973; [2] Carr and Schaber, J. Geophys. Res.

82(11), pp. 4039, 1977; [3] Sqyures, Icarus 34(3), pp. 600,

1978; [4] Squyres, J. Geophys. Res., 84(B14), pp. 8087,

1979; [5] Lucchitta, J. Geophys. Res. 89(B1), pp. 409,

1984; [6] Ikeda and Matsuoka, Permafrost Perigl. Proc.,

13(2), pp.145, 2002 [7] Berthling et al., Permafrost Perigl.

Proc., 9(2), pp. 135, 1998; [8] Mangold and Allemand,

Geophys. Res. Lett., 28(3), pp. 407, 2001.

Figure 1. Map of the Mareotis Fossae/Tempe Terra region with location of lobate debris aprons that were investigated

morphologically and morphometrically, Frames refer to HRSC (H), Viking (V) and MOC (M) image data.