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Titel |
Cold-Climate Geomorphology of Tempe Terra, Mars |
VerfasserIn |
Stephan van Gasselt, Ernst Hauber, Angelo-Pio Rossi, Alexander Dumke, Gerhard Neukum |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250036130
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Zusammenfassung |
The fretted terrain at the Martian dichotomy boundary hosts an abundance of landforms
related to the creep of mountain debris and ice which have become known as so–called lobate
debris aprons and units of lineated valley fills and concentric crater fills. Although such
features are related to different morphologic settings, there is a general consensus that
these features are in principle genetically connected to the process of ice-assisted
creep.
We here investigate lobate debris aprons in the Tempe Terra/Mareotis Fossae region of
Mars on the basis of high resolution imagery and topographic data and focus on the
emplacement and degradational history and on a mantling deposit which indicates the past
and/or present existence of near surface ice.
According to our observations we propose a multi-stage model for landscape evolution in
the Tempe Terra region, which needs further verification in other areas of the dichotomy
boundary. We have currently no observational basis for assumptions on the formation of
remnant massifs in the near–escarpment region of the highland–lowland boundary which
means that all we can say about the emplacement and distribution of remnant massifs is that
they are either autochthonous, i.e., erosional remnants of highland material or uplifted crustal
material as suggested for the southern hemispheric circum–Hellas and Argyre Planitiae
remnants.
Remnants have undergone erosional processes, be it by fluvial erosion, or be it by
gravitational processes, such as landsliding and mass wasting as well as deflation and
denudation. Additionally, cyclic obliquity changes as proposed for Mars and cyclic loss and
redeposition of volatiles and dust produced a record of ice-poor and ice-rich landforms,
respectively, that subsequently intermixed through degradational processes where the
ice/dust-rich mantling deposit either covered the remnant completely or was remobilized
gravitationally by downslope movement and revealed the underlying topography.
Apron material moving downslope forms ridges or beads as well as furrows or
crevasses as a function of compressional and tensional stresses, respectively. The
process of mantling re–deposition and gravitational mass movement has advanced
until geologically recent times, and even epsiodical events might be conceivable as
indicated by our observations. Subsequent sublimation, perhaps also initiated at
cracks and crevasses, contributed to apron degradation and revealed underlying
surfaces.
This process is thought to have been active until at least 50-100 Myr ago as crater–size
frequency distributions indicate. The activity might go on in recent times but the process of
apron degradation might be prolonged and slowly paced so that impact–crater deformation is
barely visible. |
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