Estudios preliminares de Paleomagnetismo y Magnetismo de Rocas en sedimentos del Lago Esmeralda, Isla Vega, Antártida

MARCOS A. E. CHAPARRO; JUAN M. LIRIO; HARALD N. BÖHNEL; NORBERT R. NOWACZYK; CLAUDIA S.G. GOGORZA; HECTOR NUÑEZ; ANA M. SINITO

Mendoza

Congreso; XXIV Reunión Científica de la Asociación Argentina de Geofísicos y Geodestas; 2009

Asociación Argentina de Geofísicos y Geodestas

In this work, four up to 2.5 m long sediment cores from Lake Esmeralda (Antarctica) were investigated for rock-magnetic properties and palaeomagnetic studies. The lake is a glacial lake and the clastic sediment input into the lake is mostly carried by meltwater during summer. Such lake sediments can be useful palaeoclimatic and palaeomagnetic data of the Holocene record from Antarctica; such record may span 9000 years BP according to the last glacial ice retreat in the Antarctic continent.As a collaboration work between institutions, the sediment cores were sampled and studied in four laboratories from Argentina, Mexico and Germany. The rock-magnetic measurements –magnetic susceptibility, hysteresis cycles, anhysteretic and isothermal remanent magnetisation, and thermal demagnetisation– suggest the presence of paramagnetic minerals; and that ferrimagnetic (and antiferromagnetic) minerals control the remanent magnetisation. On the other hand, sedimentological analysis evidence sediment changes that may be related to climatic changes in Antarctica. Such changes are observed from magnetic parameters as well; hence they could be used as proxies for this lake.A preliminary directional (inclination) SV curve for core Esm-7 was obtained from studies of palaeomagnetism, as well as, relative palaeointensity curves for cores Esm-4, Esm-6 and Esm-7. It may be possible to fit the Esm curves to well dated master curves from Argentina, thus contributing to establish a chronology for such sediments and other in the area.