Late holocene shifts in the latitudinal position of the southern westerly winds recorded in peat bogs in Tierra del Fuego.

MAUQUOY D, ; HUGHES PDM, ; VAN BELLEN S, ; ROLAND TP, ; DALEY TJ, ; LOADER NJ, ; PANCOTTO VA,; DE VLEESCHOUWER F, ; PAYNE RJ, ; STREET-PERROTT FA.

Congreso; VIII Southern Connection Congress; 2016

Here wereconstruct quantitative changes in water table depth using testate amoeba assemblagesrecovered from a series of rain-fed peat bogs in Tierra del Fuego. These miresurface wetness reconstructions are complemented with plant macrofossil and stable isotope data and serve as a surrogate forchanges in the strength of the Southern Westerly Winds (SWW) during the last~2000 years. We aim to reconstruct changes in the strength of the SWW in thecore region of the Southern Westerly Wind Belt (SWWB). Two patterns oflong-term changes in the SWW in southern South America have been identified inthe literature. One pattern involves a latitudinalchange in the position of the SWWBwith an anti-phased behavior of precipitation trends between the northern andsouthernmost margin of the SSWB. A secondpattern suggests that changes in the strengthof the SWW occurred throughout a largepart of the SWWB range spanning ~1000 km. Based upon the testate amoebae watertable reconstructions from our network of Sphagnummagellanicum raised peat bogsin Tierra del Fuego, water tables appear to have been relatively stable duringthe last 2000 years. However, latitudinalchanges in the position of the SWWB(poleward/equatorward shifts) may have occurred during the last ~1000 years.This is because our reconstructed precipitation trends are approximatelysynchronous but of a different sign between the core and northern margin of theSWWB. Our data suggest that a poleward shift of the SWWB occurred between ~1400-900cal. yr. BP