Preliminary relative palaeointensity record and chronology on sedimentary cores from Lake Esmeralda (Vega Island, Antarctica)

IRURZUN, M A; MARCOS A.E. CHAPARRO; SINITO, A M; GOGORZA, C S G; LIRIO, J M; NUÑEZ, H; NOWACZYK, N. R.; BÖHNEL, H. N.

Montevideo

Congreso; 3ª Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG).; 2013

Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG)

Four cores from bottom sediments of Lake Esmeralda, Vega Island, Antarctica (60°48´ S, 57°37´ W) were analysed to achieve relative palaeointensity (RPI) records. Rock magnetic studies suggest that the main carriers of magnetisation are ferrimagnetic minerals, predominantly pseudo single domain (PSD) (titano) magnetite. The magnetic grain size of the samples is in the range 1-5 microm and the variation of the inter-parametric ratios is less than one order of magnitude. Demagnetization of the natural remanent magnetization (NRM) shows a stable remanent magnetization in most of the samples. Thus, the samples fulfil the necessary conditions to calculate RPI. Radiocarbon dating was conducted on three sediment samples. Then, a combined method of radiocarbon and RPI dating were applied. The RPI records obtained in this work are in good agreement with reported records from the area and Patagonia (Argentina). According to the results, the records of Lake Esmeralda span the last 15,000 cal. BP. A hiatus was found at around 10,980 cal. BP, and apparently the sedimentation ceased during 1,800 years. The mean sedimentation rate is 0.3 mm/yr reaching a maximum of 1.3 mm/yr, which is expected for the region under study.