Preliminary Palaeomagnetic and Rock-magnetic studies on sediments from Lake Esmeralda (Vega Island), Antarctica

ANA M. SINITO; MARCOS A.E. CHAPARRO; MARÍA A. IRURZUN; JUAN M. LIRIO; NORBERT R. NOWACZYK; HARALD N. BÖHNEL; HECTOR NUÑEZ

Tandil

Congreso; 2da. Segunda Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG); 2011

LATINMAG y UNCPBA

In this work, three up to 2.5 m long sediment cores from Lake Esmeralda (Antarctica) were investigated for rock-magnetism and palaeomagnetic studies. It is a glacial lake and the clastic sediment input is mostly carried by meltwater during summer. Such lake sediments can be useful palaeoclimatic and palaeomagnetic data of the Holocene record from Antarctica. The record may span 9000 years BP according to the last glacial ice retreat in the Antarctic continent.The rock-magnetic measurements -magnetic susceptibility, hysteresis cycles, anhysteretic and isothermal remanent magnetisation, and thermal demagnetisation- suggest the presence of paramagnetic and ferrimagnetic minerals. These ferrimagnetic, and in lower proportion antiferromagnetic, minerals control the remanent magnetisation. On the other hand, sedimentological analysis evidence sediment changes that may be related to climatic changes in Antarctic Peninsula. 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 3 cores was obtained from studies of palaeomagnetism. It may be possible to fit the curve to well dated master curves from Argentina, hence contributing to establish a chronology for such sediments and others in the area.