Preliminary paleomagnetic data from the Rio Valdez paleolake outcrop (Tierra del Fuego, Argentina)

CLAUDIA GOGORZA; IRURZUN, M A; PEDRO PALERMO; ANDREA CORONATO; ANA MARÍA SINITO; ORGEIRA, M J; QUIROGA DIEGO

Puerto Vallarta

Congreso; Unión Geofísica Mexicana, Reunión Anual 2016; 2016

Unión Geofísica Mexicana

We present preliminary results of a paleomagnetic and rock-magnetic study from samples collected along a sedimentary sequence called Río Valdez paleolake in central Tierra del Fuego Island, Southernmost Argentina. The aim of this work is to carry out paleomagnetic and future paleoclimatic studies, which are scarce in this region.Magnetic susceptibility at low (kLF) and high frequency (kHF) were measured in a MS2 Bartington susceptibilimeter. The natural remanent magnetization (NRM) was step-wise demagnetized and measured on cubic samples using a JR6A magnetometer, and the paleomagnetic directions (inclination and declination) were calculated using principal component analysis (PCA). Afterward, the anhysteretic and the isothermal remanent magnetizations (ARM and IRM) were induced and measured using the same instrument in order to build a paleointensity proxy and to identify themagnetic carriers.Preliminary results indicate that the magnetic assemblage is dominated by low coercivity minerals such as magnetite pseudo single domain (PSD) as indicated by grain size ratios (kARM/kLF, ARM/SIRM). The presence of hematite in very low percentage along the sequence and greigite in a layer at the upper part was also observed. The NRM is defined by a strong, stable, single component magnetization with maximum angular deviation (MAD); values are generally below 5°. Altogether, these results suggest a genuine recording of the geomagnetic field. Using the preliminary radiocarbon- chronology, the full paleomagnetic vector (inclination,declination and relative paleointensity) is compared with the closest available record from Potrok Aike lake sediments showing good results.