Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia
Hughen, Konrad A.
MetadataShow full item record
KeywordSouthern westerlies; Inorganic geochemistry; Paleohydrology; Paleohydroclimatology; Fjord sediments; Southern South America; Chilean Patagonia
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 in 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 in 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.
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Quaternary Science Reviews 105 (2014): 195-208, doi:10.1016/j.quascirev.2014.09.021.
Showing items related by title, author, creator and subject.
Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44–47°S) : spatial variability and implications for paleoclimate reconstructions Bertrand, Sebastien; Hughen, Konrad A.; Sepulveda, Julio; Pantoja, Silvio (2011-09-22)The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy ...
Using the N/C ratio to correct bulk radiocarbon ages from lake sediments : insights from Chilean Patagonia Bertrand, Sebastien; Araneda, Alberto; Vargas, Patricia; Jana, Patricia; Fagel, Nathalie; Urrutia, Roberto (2012-06-12)The offset between AMS radiocarbon ages obtained on bulk lake sediments and the true age of deposition was evaluated at four sites in Northern Chilean Patagonia. Our results show that the bulk radiocarbon ages are ...
Fluctuations in export productivity over the last century from sediments of a southern Chilean fjord (44°S) Sepulveda, Julio; Pantoja, Silvio; Hughen, Konrad A.; Lange, Carina B.; Gonzalez, Fidelina; Munoz, Praxedes; Rebolledo, Lorena; Castro, Rodrigo; Contreras, Sergio; Avila, Alejandro; Rossel, Pamela; Lorca, Gisella; Salamanca, Marco; Silva, Nelson (2005-07-08)Here we present the first reconstruction of changes in surface primary production during the last century from the Puyuhuapi fjord in southern Chile, using a variety of parameters (diatoms, biogenic silica, total organic ...