Rock Magnetic Studies on two Sediment Cores From Lake Melincué, Argentina

IRURZUN, MARÍA A.; RUIZ FERNANDEZ, A C; MORALES, JUAN; GOGORZA, CLAUDIA; MARTINEZ, DIEGO; SINITO, ANA M.; ACHAGA, ROMINA; GOGICHAISHVILI, AVTO; SANCHEZ CABEZA, J A

Congreso; 6° Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG); 2019

Laguna Melincué is a shallow lake located in the central Pampean Plains of Argentina. This lake has been previously studied from different approaches, but more multidisciplinary studies are needed to understand its complex hydrological situation. Rock-magnetic studies on two cores (Lme 16-2-1 y Lme 16-2-2) collected from the center of the lake are presented to identify paleoclimatic proxies. The longest one (Lme16-2-1) was selected to make 210Pb dating and XRF studies. On Lme 16-2-2 measurements of natural remanent magnetization (ARM), isothermal remanent magnetization and its saturation (IRM and SIRM, respectively) and lithology description were made. Magnetic susceptibility (k) was used to correlate both cores. Rock magnetic analyses suggest that magnetic mineralogy is dominated by (titano) magnetite and/or maghemite, and also the possible formation of greigite. As a first estimate of relative magnetic grain-size variations, the median destructive field of the ARM (MDFARM) and SIRM (MDFSIRM) were determined. The changes in magnetic grain size and concentration of magnetic minerals indicate environmental variations and changes at the lake level consistent with historical reports. High resolution environmental analysis aims to obtain conclusion about the relationship between floods and agricultural exploitation in the area.