CONICET | Buscador de Institutos y Recursos Humanos

The Lake Anonima is a periglacial lake located in an ice free area from Vega Island, north eastern Antarctic Peninsula (63.8°S; 57.3°W). In this contribution, sedimentary and hydrochemical processes in the lake and surroundings were investigated, focussing on magnetic proxies for environmental processes, and their relation with the lake depositional dynamic (geology and geomorphology on modern depositional processes, lake currents, tributaries). After a detailed bathymetry, lake surface sediments were collected from a grid of 45 sites, sub-sampled and studied using rock-magnetic (magnetic susceptibility, anhysteretic and isothermal remanent magnetisation), geochemical (TOC, TIC), sedimentological (grain size) and multivariate statistical techniques. In addition, some physicochemical characteristics of snow, river and lake water samples (pH, electrical conductivity, temperature, alkalinity, total dissolved solids and dissolved oxygen) were measured in situ and laboratory. The system shows high hydrological and hydrochemical dynamic behaviour during summer time. The field observations indicate dominant evaporation processes over infiltration ones, as well as the water input is mostly supplied by snow/ice meltwater than by streams. The multiproxy analysis suggests that tributaries around the lake basin contribute to the spatial sediment variations. In particular, magnetic proxies reveal differences between clay-silt, fine and medium sand fractions; as well as between depositional areas as consequence of bottom morphology and the influence of episodic inflow into this lake. These multi parameter results not only contribute to understand the present day sedimentary processes, but also it will allow identifying the best coring sites in Lake Anonima for future environmental and magnetic studies in the past.