SGER: Holocene Variability of the South Pacific Westerly Wind Field

Stanford University, Stanford CA

Investigators

Abstract

This award, under the auspices of the Small Grants for Exploratory Research (SGER) program, will support the collection of a series of ~3.0 meter-long lake sediment cores from Lago Fagnano for a "proof-of-concept" analysis to determine which chemical tracers, if any, may be most useful for future paleoclimate studies. Situated within the Andean Cordillera of Tierra del Fuego, Lago Fagnano trends East to West across the boundary between Argentina and Chile and is the southernmost large (~120 km long) ice-free body of fresh water on Earth. Lago Fagnano lies in the path of the modern global southern hemisphere westerly wind system and is affected by tropical, subtropical, and polar ocean-atmosphere interactions. The Southern Hemisphere Westerly winds are thought to have played an important role in the regulation of atmospheric carbon dioxide concentration, the timing and style of deglaciation, and the character of the hydrologic water balance over much of southern South America. Scientific specifics are sparse regarding such past environmental variability, however, so this is a somewhat risky expedition. Lago Fagnano is a deep lake (>270 meters) in a high rainfall region of high topographic relief so the researchers expect that they have a good chance of recovering high sedimentation rate cores from the lake. This will help provide good age control that is critical to a well-calibrated paleoclimate record from the lake cores. The researcher and his colleagues will collect basic information about lake bathymetry, sediment distribution, and the basin-scale hydrologic regime in order to constrain some of the scientific risks and uncertainty associated with the region. The researcher will join Swiss and American colleagues in conducting a preliminary geophysical study of Lago Fagnano, utilizing high-resolution seismic reflection profiling that will be combined with a limited sediment piston coring campaign using available geophysical control for identification of suitable sediment accumulations. If the researchers are able to retrieve a high-resolution record of environmental change extending into the past, this will help move the paleoclimate research community forward from the standpoint of new data from a data sparse region of potential climatic importance.