CIFICEN   24414
CENTRO DE INVESTIGACIONES EN FISICA E INGENIERIA DEL CENTRO DE LA PROVINCIA DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Environmental magnetic proxies: palaeoclimatic implications for laguna Potrok Aike
Autor/es:
SINITO, A.M.; IRURZUN, M.A.; ORGEIRA, MARÍA J.; GOGORZA, C. S.; ZOLITSCHKA, BERND
Lugar:
Mérida
Reunión:
Congreso; 12th Scientific Assembly; 2013
Institución organizadora:
International Association of Geomagnetism and Aeronomy
Resumen:
This study was carried out on three piston cores collected from Laguna Potrok Aike (51°57?S, 70°24?W), a deep maar lake in southern South America. Magnetic measurements (magnetic susceptibility at low and high frequency, anhysteretic remanent magnetisation, saturated isothermal remanent magnetisation, remanentcoercivity) were performed on sub-samples from about 15,500 cal. BP to the present and associated parameters like soft-IRM, S-ratio, ARM/X, SIRM/X and ARM/ SIRM were also calculated. A simple model based on concentration of magnetic parameters, magnetic grain size and magnetic mineralogy is proposed in order to infer lake level and wind changes. Under consideration of similar magnetic mineralogy, when allochthonous sediment dominated, variations of magnetic concentration and grain size indicate lake level fluctuations. High/low values of both parameters were found for high/low lake levels.Magnetic susceptibility shows the best fit with hydrological changes. In addition, during dry periods a low percentage of greigite is observed indicating lake stratification. Geochemical data and coarse magnetic grain size suggest an eolian sediment source for these periods. According to this study, Laguna Potrok Aike was stratified at least four times during the studied time interval, probably due to the weakening of the Southern Hemispheric Westerlies. More studies are needed in order to characterize the greigite that was identified in the sediment record and to establish the associated environmental characteristics.Relationships between magnetic parameters, total organic carbon, total inorganic carbon, different elements, gastropods, pollen and diatoms were analysed to support our model.