Rock-Magnetic Studies on Paleolake Sediments from Tajamar Formation

IRURZUN, M.A.; LARCHER, N.; GONZÁLEZ BONORINO, G.; C. S. G. GOGORZA

Tandil

Congreso; Segunda Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LatinMag).; 2011

LatinMag/UNCPBA

In this paper we conducted a detailed study of rock magnetism to characterize sediments obtained from three cores located in an outcrop in Guachipas (25º 31´S 65° 30.5 ´W), Tajamar Formation. Guachipas sediments are located in the river drainage of Guachipas River, which drains Meso-Cenozoic outcrops thatbordering the southern end of the Lerma valley. Measurements of magnetic susceptibility (specific, χ and volumetric, k), declination, inclination andintensity of the natural remanent magnetization (D, I and NRM), anhisteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM), reaching saturation (SIRM) were performed. A reverse field was applied to determine the coercivity of remanence (BCR). Associated parameters werecalculated. The stability of the NRM was analyzed by alternating field demagnetization. The studied samples showed a viscous remanent magnetization (VRM) removed with alternating fields of about 10-15mT., Inclination vary around -20° and declination around 1°.The magnetic properties haveshown highly variable values, showing changes in both grain size and concentration of magnetic minerals. It was found that the main carrier of remanence is magnetite with the presence of hematite in differentpercentages.