Preliminary Paleomagnetic Data From The Rio Valdez Paleolake Outcrop (Tierra Del Fuego, Argentina)

MARIA JULIA ORGEIRA; DIEGO QUIROGA; PEDRO PALERMO; ANDREA CORONATO; ANA M. SINITO; CLAUDIA GOGORZA; MARÍA IRURZUN

Puerto Vallarta

Congreso; Reunión Anual de la Unión Geofísica Mexicana (UGM 2016); 2016

Unión Geofísica Mexicana

We present preliminary results of a paleomagnetic and rock-magnetic studyfrom samples collected along a sedimentary sequence called Río Valdezpaleolake in central Tierra del Fuego Island, Southernmost Argentina. Theaim of this work is to carry out paleomagnetic and future paleoclimaticstudies, which are scarce in this region.Magnetic susceptibility at low (kLF) and high frequency (kHF) weremeasured in a MS2 Bartington susceptibilimeter. The natural remanentmagnetization (NRM) was step-wise demagnetized and measured on cubicsamples using a JR6A magnetometer, and the paleomagnetic directions(inclination and declination) were calculated using principal componentanalysis (PCA). Afterward, the anhysteretic and the isothermal remanentmagnetizations (ARM and IRM) were induced and measured using the sameinstrument in order to build a paleointensity proxy and to identify themagnetic carriers.Preliminary results indicate that the magnetic assemblage is dominated bylow coercivity minerals such as magnetite pseudo single domain (PSD) asindicated by grain size ratios (kARM/kLF, ARM/SIRM). The presence ofhematite in very low percentage along the sequence and greigite in a layerat 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 agenuine recording of the geomagnetic field. Using the preliminaryradiocarbon- chronology, the full paleomagnetic vector (inclination,declination and relative paleointensity) is compared with the closestavailable record from Potrok Aike lake sediments showing good results.