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Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia

Bertrand, Sébastien ; Hughen, Konrad ; Sepúlveda, Julio ; Pantoja, Silvio

Quaternary science reviews, 2014-12, Vol.105, p.195-208 [Periódico revisado por pares]

Elsevier Ltd

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  • Título:
    Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia
  • Autor: Bertrand, Sébastien ; Hughen, Konrad ; Sepúlveda, Julio ; Pantoja, Silvio
  • Assuntos: Chilean Patagonia ; Fjord sediments ; Inorganic geochemistry ; Marine ; Paleohydroclimatology ; Paleohydrology ; Southern South America ; Southern westerlies
  • É parte de: Quaternary science reviews, 2014-12, Vol.105, p.195-208
  • Notas: ObjectType-Article-1
    SourceType-Scholarly Journals-1
    ObjectType-Feature-2
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  • Descrição: The climate of Chilean Patagonia is strongly influenced by the southern westerlies, which control the amount and latitudinal distribution of precipitation in the southern Andes. In austral summer, the Southern Westerly Wind Belt (SWWB) is restricted to the high latitudes. It expands northward in winter, which results in a strong precipitation seasonality between ∼35 and 45°S. Here, we present a new precipitation seasonality proxy record from Quitralco fjord (46°S), where relatively small latitudinal shifts of the SWWB result in large changes in precipitation seasonality. Our 1400 yr record is based on sedimentological and geochemical data obtained on a sediment core collected in front of a small river that drains the Patagonian Andes, which makes this site particularly sensitive to changes in river discharge. Our results indicate Fe/Al and Ti/Al values that are low between 600 and 1200 CE, increasing at 1200–1500 CE, and high between 1500 and 1950 CE. Increasing Fe/Al and Ti/Al values reflect a decrease in mean sediment grain-size from 30 to 20 μm, which is interpreted as a decrease in seasonal floods resulting from an equatorward shift of the SWWB. Our results suggest that, compared to present-day conditions, the SWWB was located in a more poleward position before 1200 CE. It gradually shifted towards the equator in 1200–1500 CE, where it remained in a sustained position until 1950 CE. This pattern is consistent with most precipitation records from central and southern Chile. The comparison of our record with published regional sea surface temperature (SST) reconstructions for the late Holocene shows that equatorward shifts of the SWWB are systematically coeval with decreasing SSTs and vice versa, which resembles fluctuations over glacial–interglacial timescales. We argue that the synchronicity between SST and SWWB changes during the last 1400 years represents the response of the SWWB to temperature changes in the Southern Hemisphere. [Display omitted] •1400 yr record of seasonal flood intensity in northern Chilean Patagonia.•Precipitation seasonality was high in 600–1200 CE, lowest in 1500–1950 CE.•Changes in precipitation seasonality reflect latitudinal variations of the SWWB.•Equatorward shift of the SWWB is coeval with decreasing SSTs.•Absence of SWWB and SST changes associated to the MCA or LIA.
  • Editor: Elsevier Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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