Magnetic properties of lake Bannoe sediments (Southern Urals, Russia)

Relevance. Lake sediments contain the unique data on mineral composition and physical properties reflecting environmental and climate changes over the past millennia. These data are extremely important for understanding environmental processes today and in the future. Magnetic minerals and properties are considered as essential to reconstruct sediment supply and climate fluctuations. Aim. To reveal magnetic susceptibility and coercive spectrometric parameters relevant for lake cores stratification in accordance with climate terms. Object. Core of Lake Bannoe sediments (length is cm). The age of the core is similar to 12.5 thousand years old. Materials and methods. The magnetic susceptibility was measured using MFK-1A Kappabridge (AGICO). The hysteresis parameters of the studied sedimentary deposits were determined using a coercive spectrometer (J_meter). Induced magnetization based differential thermomagnetic analysis was performed on auto-registering magnetic torsion balance using the zero method. Results. The magnetic susceptibility of sediments taken from Lake Bannoe ranges from 0.88 to 7,87 center dot 10(-7)m(3)/kg. Differential thermomagnetic analysis revealed the presence magnetite in these sediments. The Day-Dunlop plot indicated that the magnetic grains in the samples of Lake Bannoe are mix of single-domain and multi-domain (pseudo-single-domain) particles, with multi-domain grains comprising 70 to 92% the total. Variations in magnetic susceptibility and its components were analyzed in relation to the Holocene climatic stages as defined by the Blytt-Sernander classification. Conclusions. It is found that the variations in magnetic properties of studied sediments are in harmony with climate stages of the Holocene. Sediments of Lake Bannoe recorded the Bond event #8 (similar to 11100 years ago), as well as regional aridization events which occurred similar to 4500 and similar to 2000 years ago. The results obtained during this study complement already existing paleoclimatology data, which will be interesting to a wide range researchers - from paleoclimatologists to limnologists and ecologists.