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Helmut Weissert receives Jean Baptiste Lamarack Medel 2013
for his fundamental contribution to the application of carbon-isotope geochemistry to stratigraphy and palaeoceanography.
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New Science study about the ENSO variability
Lago Cardiel is a closed lake basin in southern Argentina (49S) lying on the Patagonian plateau between the Andean cordillera and the Atlantic coast, at an altitude of 276 m.a.s.l. The lake is situated in a tectonic depression covering a modern surface area of about 370 km2 and has a maximum water depth of 76 m. Mean annual precipitation in the area of the lake is relatively low (~150 mm) due to the orographic rain shadow effect on the Southern Westerlies. But as the lake’s catchment area is mostly located to the west, it is characterized by a steep precipitation gradient receiving an annual precipitation of up to 500 mm. This geographical setting within a precipitation gradient makes the lake a sensitive recorder of past changes in the regional climate as shown by a series of palaeo-shorelines indicating past lake level changes (Stine and Stine, 1990). A combined approach of seismic surveying and analyzing sedimentary cores permitted to identify, map the extent, and date past lake level fluctuations.
Seismic investigations using different acoustic sources have imaged in
detail the sub-surface of the basin (Beres et al., 2008; Gilli et al.,
2001; Gilli et al., 2005a). Lago Cardiel was shallow with a probable
water depth of only few meters during the Late Glacial. A desiccation
period of a few hundred years occurred after 13.16 Ka BP. This was
followed by a large change in the hydrological balance as observed in a
large transgression in the early Holocene with a lake level rise of
over up to 120 meters (Markgraf et al., 2003; Stine and Stine, 1990).
Lake level subsequently receded, but never fell significantly below the
modern level during the entire Holocene. The onset of strong westerly
winds around 6800 cal years BP caused a strong and persistent focus of
the sediment in the center of the lake basin (Gilli et al. 2005b).
Beres, M., Gilli, A., Ariztegui, D. and Anselmetti, F.S., 2008, The
Lago Cardiel basin, Argentina (49°S): Origin and evolution revealed by
high-resolution multi-channel seismic reflection studies: Journal of
South American Earth Sciences, v. 25, p. 74-85. (pdf, 2.8MB)
Gilli, A., Anselmetti, F.S., Ariztegui, D., Bradbury, J.P., Kelts,
K.R., Markgraf, V., and McKenzie, J.A., 2001, Tracking abrupt climate
change in the Southern Hemisphere: a seismic stratigraphic study of
Lago Cardiel, Argentina (49 degrees S): Terra Nova, v. 13, p. 443-448. (pdf, 1.1MB)
Gilli, A., Anselmetti, F.S., Ariztegui, D., Beres, M., McKenzie, J.A.,
and Markgraf, V., 2005a, Seismic stratigraphy, buried beach ridges and
contourite drifts: the Late Quaternary history of the closed Lago
Cardiel basin, Argentina (49 degrees S): Sedimentology, v. 52, p. 1-23. (pdf, 5.5MB)
Gilli, A., Ariztegui, D., Anselmetti, F.S., McKenzie, J.A., Markgraf,
V., Hajdas, I., and McCulloch, R.D., 2005b, Mid-Holocene strengthening
of the Southern westerlies in South America - Sedimentological
evidences from Lago Cardiel, Argentina (49 degrees S): Global and Planetary Change, v. 49, p. 75-93. (pdf, 1.1MB)
Markgraf, V., Bradbury, J.P., Schwalb, A., Burns, S., Stern, C., Ariztegui, D., Gilli, D., Anselmetti, F.S., Stine, S., and Maidana, N., 2003, Holocene paleoclimate of Southern Patagonia: Limnological and environmental history of Lago Cardiel, Argentina: The Holocene, v. 13, p. 581-591. (pdf, 952KB)
Stine, S., and Stine, M., 1990, A record from Lake Cardiel of climate in southern South America, Nature, v. 345, p. 705–708. (pdf, 452KB)
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