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| Titel |
Paleoglacier reconstruction of the central massif of Gredos range during
Last Glacial Maximum. |
| VerfasserIn |
Néstor Campos, Luis Miguel Tanarro |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152935
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| Publikation (Nr.) |
 EGU/EGU2017-17845.pdf |
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| Zusammenfassung |
| The accurate reconstruction of paleoglaciers require a well determined extent and morphology of
them, one of the main problems is the absence of glacial geomorphic evidences which made
possible the delimitation of the ice limits, for this reason physical-based models are
useful for ice surface reconstruction in areas where geomorphological information is
incomplete.
A paleoglacier reconstruction during its maximum extension is presented for a high
mountain area of the western part of the central massif of Gredos range, in the
center of Iberian Peninsula, this area is located 30 km west of Almanzor (40˚ 14′
48? N; 5˚ 17′ 52? W; 2596 m a.s.l.), the highest peak of Iberian Central System
(ICS) and covers five gorges: La Nava, Taheña- Honda, La Vega, San Martín and
Los Infiernos, the first three facing North, San Martin facing Northwest and Los
Infiernos facing West. Despite the existence of some works analyzing the extension
of paleoglaciers in the ICS during its maximum extension, there is still a need to
improve the understanding of this zone, to provide a more detailed knowlegde of the
evolution of the range and to know more in detail the full extent of paleoglaciers in this
area.
For delimitate the glaciated area the most distant frontal moraines with a larger
geomorphological entity that indicates a great advance or a prolonged stay and stabilization
which would presumably correspond with the maximum advance of the glaciers have
been mapped, for that, photo interpretation of digital aerial photographs (25 cm
resolution) has been done, in some areas where the location or limits of the moraines
were not clear 3D images were used, all the work was complemented with detailed
field surveys. Once the ice limits have been determined is necessary to estimate
the topography of the paleoglaciers, for that purpose a simple steady-state models
that assume a perfectly plastic ice rheology have been used, reconstructing the
theoretical ice profiles and obtaining the extent of the paleoglaciers (based on the largest
moraines of the front and sides of the valley as the main indicator of the LGM), in
order to reconstruct the ice surface we calculated longitudinal profiles, with these
reconstructed profiles a digital elevation model (DEM) of 5 m pixel size was created
and combined with actual topography in order to obtain the ice thickness at the
LGM.
The combination of these physical-based models and geomorphological evidences has
demonstrated to be a successful method to reconstruct the topography of paleoglaciers, the
most distant frontal moraines of the studied area are located at different altitudes
depending on the paleoglacier, the lower altitude of a frontal moraine is 1320 meters and
the higher is located at 1570 meters, the preliminary results show that during the
LGM, the studied paleoglaciers had a maximum ice thickness of 366 meters in La
Vega gorge, with a total volume of 28.56 x 108 m3 and a mean paleoELA of 1940
meters.
References:
Benn, D.I., Hulton, N.R.J., 2010. An ExcelTM spreadsheet program for reconstructing
the surface profile of former mountain glaciers and ice caps. Computers & Geosciences 36,
605e610.
Schilling, D.H., Hollin, J., 1981. Numerical reconstructions of valley glaciers and small
ice caps. In: Denton, G.H., Hughes, T.J. (Eds.), The Last Great Ice Sheets. Willey, New York,
USA, pp. 207e220.
Research funded by Deglaciation project (CGL2015-65813-R), Government of Spain |
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