Exposure dating of Late Glacial and pre-LGM moraines in the Cordon de Doña Rosa, Northern/Central Chile (~ 31°S)

Zech, Roland; Kull, Christoph; Kubik, Peter; Veit, Heinz (2007). Exposure dating of Late Glacial and pre-LGM moraines in the Cordon de Doña Rosa, Northern/Central Chile (~ 31°S). Climate of the past, 3(1), pp. 1-14. Göttingen: Copernicus Publications 10.5194/cp-3-1-2007

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Biogeochemistry and Paleoclimate
08 Faculty of Science > Institute of Geography > Physical Geography > Unit Paleo-Geoecology
08 Faculty of Science > Institute of Geography

UniBE Contributor:

Zech, Roland and Veit, Heinz

Subjects:

900 History > 910 Geography & travel

ISSN:

1814-9324

Publisher:

Copernicus Publications

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:59

Last Modified:

29 Sep 2015 16:45

Publisher DOI:

10.5194/cp-3-1-2007

Web of Science ID:

000244506800001

BORIS DOI:

10.7892/boris.25569

URI:

https://boris.unibe.ch/id/eprint/25569 (FactScience: 59202)

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