ROCK MAGNETIC STUDIES ON TWO SEDIMENT CORES FROM LAKE MELINCUÉ, ARGENTINA

ACHAGA, R.; C. S. G. GOGORZA; A. IRURZUN; A. GOGICHAISHVILI; D.A. MARTINEZ; A. C. RUIZ FERNANDEZ; J.A. SÁNCHEZ CABEZA; A. M. SINITO; JUAN MORALES

Santiago

Congreso; VI Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LatinMag).; 2019

Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LatinMag). - Sede Chile

 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 and Lme 16-2-2, collected from the center of the lake are presented in order to identify paleoclimatic proxies. The longest one (Lme 16-2-1) was selected to make 210Pb dating and XRF studies. On Lme 16-2-2 measurements of natural remanent magnetization (NRM), alternating field (AF) demagnetization, anhysteretic 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 possibly also greigite. As a first estimate of relative magnetic grain-size variations, the median destructivefield 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.