CHANGES IN THE SEDIMENTATION RATES AS INDICATORS OF THE EL NIÑO-LA NIÑA CLIMATIC EVENT IN LAKE MASCARDI (PATAGONIA, ARGENTINA)

GUSTAVO VILLAROSA; JULIETA MASSAFERRO; DANIEL ARIZTEGUI; ARTURO AMOS

Durban, South Africa

Congreso; INQUA XV International Congress; 1999

Iternational Union for Quaternary Research (INQUA)

In the present paper we show the preliminary results of the analysis of sedimentation rates data obtained through 1992-1998 continuous sample collection. Sampling sites were located in the Northwest branch of Lake Mascardi. This branch was chosen mainly because it is fed by the Manso River, which carries melt-waters from most of the Argentinean glaciers of Mount Tronador, and precipitation input from temporary and permanent streams. The sediment was regularly collected using TRYPTON samplers. Each sampler consists of two sediment traps that were set at different depths, one at 5 m from the surface just above the thermocline and, the other one, at the bottom of the lake (120 m from the surface). During the first two years (1992-1994), data was obtained from four TRYPTON samplers with which a preliminary sedimentation model was developed (Valverdu et al., 1994). The following sedimentation controls were carried out with one sampler. The correlation of both, the detailed climatic information (precipitation, temperature, etc) obtained from a meteorological station located in the Manso River-Lake Mascardi basin and. the changes in the sediment records, allowed us to associate them with the influence of El Niño-La Niña climatic events. Our results show that (i) the sediment record clearly reflect the presence of wet-warm and cold-dry periods (ii) this episodes can be traced in the past analysing the lake sedimentary record. (precipitation, temperature, etc) obtained from a meteorological station located in the Manso River-Lake Mascardi basin and. the changes in the sediment records, allowed us to associate them with the influence of El Niño-La Niña climatic events. Our results show that (i) the sediment record clearly reflect the presence of wet-warm and cold-dry periods (ii) this episodes can be traced in the past analysing the lake sedimentary record.