 |
| Titel |
Mapping of Postglacial Icelandic Lava Flows as Analogues for Mars |
| VerfasserIn |
Ernst Hauber, Thomas Platz, Laetitia Le Deit, Oryaelle Chevrel, Bernd Hoffmann, Lena Kuhlmann, Frank Trauthan, Frank Preusker, Ralf Jaumann  |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250057088
|
|
|
|
|
|
| Zusammenfassung |
| Mapping of lava flows on extraterrestrial surfaces is commonly complicated by a lack of
detailed topography, by lava flow degradation, and in particular on Mars, by widespread dust
mantling. Mapping of terrestrial analogues is therefore important for any attempt to interpret
remote sensing data of planetary lava flows. We performed a flight campaign with an airborne
version of the High Resolution Stereo Camera, HRSC-AX, for the acquisition of stereo and
colour images of postglacial lava flows in Iceland as analogues to basaltic lava flows on Mars.
The flight campaign in summer 2006 covered several regions, including parts of the Western
Volcanic Zone (WVZ). Orthophotographs have a map-projected resolution of 25Â cm pixel-1,
and Digital Elevation Models (DEM) have a vertical resolution of 10Â cm, an absolute
accuracy of ~20Â cm, and a horizontal grid spacing of 1Â m. Images and DEM were
mapped to determine the overall extent and morphology of lava flows, and field work
in summer 2010 was conducted to verify and refine the mapping results and to
collect samples for further laboratory analysis (mineralogy, chemistry, rheology).
In general, the region is characterized by ubiquitous vents and fissures. Vents are
often craters with rims consisting of scoria and partly welded spatter. Lava flows
consist of vesicular basalt, have well expressed flow margins, and display inflation
features (e.g., tumuli). Most lava flows are covered by moss, the type and thickness of
which can sometimes be used to differentiate between lava flows of different age.
Lava flow textures are commonly characterized by ropy pahoehoe, but blocky lavas
are also found. Lava flow occurred both in lava tubes and as open channel flows.
Many partly drained channels suggest that these lava flows were volume-limited.
In this study we present results of the investigation of one selected lava flow, the
outline of which was mapped using false-colour ortho-images, shaded DEM, and
slope maps. Lava transport is predominantly in lava tubes near the first 1-1.5Â km
from the vent. After a sharp break in slope (about halfway down the lava flow),
the flow continues in open-channel flow conditions over very shallow terrain. The
total length of the flow is about 4Â km. It proved to be difficult (but possible) to
identify the correct location of the vent in image data, which was confirmed by field
inspection. It is even more complicated to find the source vents of Martian lava flows,
and our results suggest that an unambiguous identification will only be possible in
a few fortunate cases. Our results also show that the preexisting topography is a
significant factor in determining the final shape of a lava flow. In turn, the observation of
changes in flow morphology of planetary lava flows may allow inferring topographic
variations even for planetary surfaces where no topographic data are available. Further
work will combine the results of our mapping with laboratory results on rheology,
allowing to test rheological flow models that are based on lava flow morphometry. The
combination of photogeological mapping, field mapping, and laboratory analysis might
improve our ability to infer compositional and rheological information from the
mapping of planetary data, and to assess emplacement conditions and controls. |
|
|
|
|
|
|