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| Titel |
A first 10Be cosmogenic glacial chronology from the High Atlas, Morocco, during the last glacial cycle. |
| VerfasserIn |
David Fink, Philip Hughes, Cassie Fenton |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087875
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| Publikation (Nr.) |
 EGU/EGU2014-1931.pdf |
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| Zusammenfassung |
| Glacial geomorphological mapping, 10Be cosmogenic exposure ages of 21 erratics from
cirque-valley systems and paleo-glacier climate modelling in the High Atlas Mountains,
Morocco (31.1°N, 7.9°W), provides new and novel insights as to the history and evolution
of the largest desert region on Earth. The Atlas Mountains display evidence of
extensive and multiple Late Pleistocene glaciations whose extent is significantly
larger than that recognised by previous workers. The largest glaciers formed in the
Toubkal massif where we find 3 distinct phases of glacial advances within the last
glacial cycle. The oldest moraines occurring at the lowest elevations have yielded
eight 10Be ages ranging from 30 to 88 ka. Six of eight samples from moraines
at intermediate elevations gave ages of 19 to 25 ka (2 outliers) which correlates
well with the global Last Glacial Maximum (ca. 26-21 ka) and the last termination
during marine isotope stage 2. Five erratics from the youngest and most elevated
moraines yielded a suite of normally distributed exposure ages from 11 to 13 ka which
supports a correlation with the northern hemisphere Younger Dryas (12.9-11.7
ka). The glacial record of the High Atlas effectively reflects moisture supply to the
north-western Sahara Desert and can provide an indication of shifts between arid
and pluvial conditions. The plaeo equilibrium line altitudes (ELA) of these three
glacier phases was more than 1000 m lower than the predicted ELA based on today’s
temperatures. Glacier-climate modelling indicates that for each of these glacier phases
climate was not only significantly cooler than today, but also much wetter. The new
evidence on the extent, timing and palaeoclimatic significance of glaciations in
this region has major implications for understanding moisture transfer between
the North Atlantic Ocean and the Sahara Desert during Pleistocene cold stages. |
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