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| Titel |
LGM Tibetan Plateau glaciers were not much larger than today |
| VerfasserIn |
Jakob Heyman, Arjen P. Stroeven, Clas Hättestrand, Helena Alexanderson, Marc W. Caffee, Ping Fu, Jon Harbor, Alun Hubbard, Yingkui Li, Liping Zhou |
| 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 |
250044099
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| Zusammenfassung |
| The Tibetan Plateau is the largest and highest elevated area on Earth with consequential
impacts on regional (monsoon development) and global (CO2 sequestering) climate patterns
and evolution, and with its glaciers providing meltwater for some of the largest rivers of the
world. The glacial history of the Tibetan Plateau is dominantly characterized by glaciers and
ice caps centered on elevated mountain regions of the plateau, as evidenced by an extensive
glacial geological record. Here we present the outcome of a five year project aiming towards
a palaeoglaciological reconstruction for the Bayan Har Shan region of the northeastern
Tibetan Plateau. We have used remote sensing, field studies and 10Be exposure ages towards
a robust reconstruction of former glaciation. Glacial landforms and sediments in Bayan Har
Shan, distributed around elevated mountain areas, indicate a maximum Quaternary glaciation
significantly larger than today. We have dated 40 boulders, 12 surface pebbles samples,
and 15 depth profile samples (in 4 depth profiles) from 15 sites (mainly moraine
ridges) using 10Be exposure dating. Our boulder and pebble exposure ages range
from 3 ka to 128 ka with large age spreads within populations of individual sites.
Based on the premise that cosmogenic age spreads within populations are caused by
post-depositional shielding which yields exposure ages younger than deglaciation
ages (see Heyman et al. Abstract/Poster in session CL4.7/GM2.4/SSP2.5/SSP3.9:
EGU2010-14159-1) and based on the exposure ages of the multiple sample types, all dated
glacial deposits pre-date the global Last Glacial Maximum (LGM). Our results further
indicate that even the innermost and highest of the dated moraines, formed by glaciers |
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