MAGNETIC CHARACTERIZATION OF SEDIMENTS FROM LAKE FONCK CHICO, ARGENTINA

A. IRURZUN; F. PETRUZZELLA; C. S. G. GOGORZA; J. MASSAFERRO; A.M. SINITO

Santiago

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

In this work, we present the results of magnetic mineralogy, concentration and grain size in a sedimentary core collected from Lake Fonck Chico (41°18′36″ S 71°47′13″ W). Cyclic variations of magnetic mineralogy, as well as, in the amount of iron oxides are observed. Magnetic grain size also shows a cyclic behaviour and a decreasing grain size trend for the first 50 cm. Low S ratio values indicates the presence of high coercivity minerals that suggests the contribution of iron sulphurs and/or antiferromagnetic minerals in some periods. Magnetic susceptibility shows sectors with very low values indicating less clastic material and according to the lithology, higher percentage of organic matter. Changes in the remanence ratio suggest hydrologic variations, particularly, in four sectors, which would indicate a fall in the lake level. Frequency factor F suggests the presence of superparamagnetic grains, in general, associated to in situ processes.