ROCK MAGNETIC STUDIES FROM THE RIO VALDEZ PALEOLAKE OUTCROUP (TIERRA DEL FUEGO, ARGENTINA): PRELIMINARY RESULTS

We present preliminary results of a rock-magnetic study from a group of pilot samples collected along a sedimentary sequence called Rio Valdez paleolake in central Tierra del Fuego Island, Southernmost Argentina. The aim of this work is to characterize these sediments in order to carry out future paleomagnetic and paleoclimatic studies, which are scarce in this region (Gogorza et al., 2012, 2013; Lise-Pronovost et al., 2013). The results mainly include measurements of magnetic susceptibility in low and high frequency, natural remanence magnetization (NRM), isothermal remanent magnetization (IRM), saturation isothermal remanent magnetization (SIRM), back field and anhysteretic remanent magnetization at 100 mT (ARM). Associated parameters (ARM/k, SIRM/ARM and SIRM/k) were calculated. Additionally, we present results of magnetic NRM parameters measured with vibrating sample magnetometer (VSM). It was found that the main carrier of remanence is magnetite with the presence of hematite in very low percentage; also greigite was observed in a layer at the upper part of the sequence.