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| Titel |
Exposure dating of Late Glacial and pre-LGM moraines in the Cordon de Doña Rosa, Northern/Central Chile (~31° S) |
| VerfasserIn |
R. Zech, Ch. Kull, P. W. Kubik, H. Veit |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 3, no. 1 ; Nr. 3, no. 1 (2007-01-15), S.1-14 |
| Datensatznummer |
250000737
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| Publikation (Nr.) |
 copernicus.org/cp-3-1-2007.pdf |
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| Zusammenfassung |
| Despite the important role of the Central Andes (15–30° S) for climate
reconstruction, knowledge about the Quaternary glaciation is very limited
due to the scarcity of organic material for radiocarbon dating. We applied
10Be surface exposure dating (SED) on 22 boulders from moraines in the
Cordon de Doña Rosa, Northern/Central Chile (~31° S). The
results show that several glacial advances in the southern Central Andes
occurred during the Late Glacial between ~14.7±1.5 and 11.6±1.2 ka.
A much more extensive glaciation is dated to ~32±3 ka, predating the temperature minimum of the global LGM (Last Glacial
Maximum: ~20 ka). Reviewing these results in the paleoclimatic
context, we conclude that the Late Glacial advances were most likely caused
by an intensification of the tropical circulation and a corresponding
increase in summer precipitation. High-latitude temperatures minima, e.g.
the Younger Dryas (YD) and the Antarctic Cold Reversal (ACR) may have
triggered individual advances, but current systematic exposure age
uncertainties limit precise correlations. The absence of LGM moraines
indicates that moisture advection was too limited to allow significant
glacial advances at ~20 ka. The tropical circulation was less
intensive despite the maximum in austral summer insolation. Winter
precipitation was apparently also insufficient, although pollen and marine
studies indicate a northward shift of the westerlies at that time. The
dominant pre-LGM glacial advances in Northern/Central Chile at ~32 ka
required lower temperatures and increased precipitation than today. We
conclude that the westerlies were more intense and/or shifted equatorward,
possibly due to increased snow and ice cover at higher southern latitudes
coinciding with a minimum of insolation. |
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