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| Titel |
Mapping Medusae Fossae Formation materials in the southern highlands of Mars |
| VerfasserIn |
Samantha Harrison, Matt Balme, J. B. Murray, Axel Hagermann, Jan-Peter Muller |
| 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 |
250040554
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| Zusammenfassung |
| The Medusae Fossae Formation (MFF) is an extensive deposit (2.2 x 106 km2,
Bradley et al., (2002)) of wind-eroded material of widely debated origin which
unconformably overlies a considerable area of the crustal dichotomy boundary on
Mars.
The MFF has been mapped into five main outcrops and three geological members
according to exposure and stratigraphy and away from the three main lobes are numerous
outliers of MFF materials. These have mainly been reported in the northern lowlands regions
but few studies have examined the possibility of MFF outliers on high ground south of the
dichotomy boundary.
An intensive study of MOC NA images across the Mangala Valles region of Mars has
resulted in many observations of materials with morphology strikingly similar to some
examples of the MFF. These examples are typified by yardang fields and have a similar
patchy and discontinuous nature to materials of the upper member of the MFF. Most have
consistent lineation orientations across the wider area, which match the dominant orientation
of yardangs in the main MFF outcrops. Furthermore, elevation data shows that the maximum,
minimum and mean elevations of these materials are closest to those of the upper member of
the MFF.
We therefore conclude that these deposits are MFF outliers and that they probably
represent remnant upper member material. We suggest that there might be two possible
explanations for these outliers: 1) the MFF had a much greater pre-erosional extent
than previously estimated, or 2) Materials from the main outcrops were eroded and
then blown south to accrue in the highland areas, where they were subsequently
reworked.
We suggest that the topography of the region favours the first option. We outline an
“overflowing” layer-cake deposition model, in which layers of sediment stacked up against
the dichotomy boundary until they reached the topographic level of the highlands. Further
materials (that went on to become upper-member MFF material and outliers) were then
deposited across a wider area, including south of the dichotomy boundary. Such an
onlap suggests a volcaniclastic origin for the Medusae Fossae Formation materials. |
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