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| Titel |
Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina) |
| VerfasserIn |
J. Zhu, A. Lücke, H. Wissel, C. Mayr, D. Enters, K. Ja Kim, C. Ohlendorf, F. Schäbitz, B. Zolitschka  |
| 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 ; 10, no. 6 ; Nr. 10, no. 6 (2014-12-09), S.2153-2169 |
| Datensatznummer |
250117084
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| Publikation (Nr.) |
 copernicus.org/cp-10-2153-2014.pdf |
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| Zusammenfassung |
| The Southern Hemisphere Westerlies (SHW) play a crucial role in large-scale
ocean circulation and global carbon cycling. Accordingly, the reconstruction
of how the latitudinal position and intensity of the SHW belt changed during
the last glacial termination is essential for understanding global climatic
fluctuations. The southernmost part of the South American continent is the
only continental mass intersecting a large part of the SHW belt. However,
due to the scarcity of suitable palaeoclimate archives continuous proxy
records back to the last glacial are rare in southern Patagonia. Here, we
show an oxygen isotope record from cellulose and purified bulk organic
matter of submerged aquatic moss shoots from Laguna Potrok Aike
(52° S, 70° W), a deep maar lake located in semi-arid,
extra-Andean Patagonia, covering the last glacial–interglacial transition
(26 000 to 8500 cal BP). Based on the highly significant correlation
between oxygen isotope values of modern aquatic mosses and their host waters
and abundant well-preserved moss remains in the sediment record a
high-resolution reconstruction of the lake water oxygen isotope (δ18Olw-corr) composition is presented. The reconstructed δ18Olw-corr values for the last glacial are ca.
3‰ lower than modern values, which can best be explained
by generally cooler air temperatures and changes in the moisture source
area, together with the occurrence of permafrost leading to a prolonged lake
water residence time. Thus, the overall glacial δ18Olw-corr level until 21 000 cal BP is consistent with a
scenario of weakened or absent SHW at 52° S compared to the
present. During the last deglaciation, reconstructed δ18Olw-corr values reveal a significant two-step rise describing
the detailed response of the lake's hydrological balance to this fundamental
climatic shift. Rapid warming is seen as the cause of the first rise of ca.
2&permil, in δ18Olw-corr during the first two
millennia of deglaciation (17 600 to 15 600 cal BP) owing to more 18O
enriched precipitation and increasing temperature-induced evaporation.
Following this interpretation, an early strengthening of the SHW would not
be necessary. The subsequent decrease in δ18Olw-corr by up
to 0.7‰ marks a millennial-scale transition period
between 15 600 and 14 600 cal BP interpreted as the transition from a
system driven by temperature-induced evaporation to a system more dominated
by wind-induced evaporation. The δ18Olw-corr record
resumes its pronounced increase around 14 600 cal BP. This further
cumulative enrichment in 18O of lake water could be interpreted as
response to strengthened wind-driven evaporation as induced by the
intensification and establishment of the SHW at the latitude of Laguna
Potrok Aike (52° S) since 14 600 cal BP. δ18Olw-corr approaching modern values around 8500 cal BP reflect
that the SHW exerted their full influence on the lake water balance at that
time provoking a prevailing more arid steppe climate in the Laguna Potrok Aike region. |
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