Day plots of bacterial magnetite from sediments of Shira lake (Khakassia, Russia)

The domain state of magnetite detected in sediments of Shira lake (Khakassia, Russia) was examined by means of magnetic hysteresis. Analysis of experimental data obtained on samples from different parts of bottom sediment cores in terms of Day plots allowed us to conclude that magnetite particles are in the pseudo-single-domain state. This indicates respectively small size of magnetite particles ($< 100$ nm) and reveals their bacterial origin. Biogenic magnetite buried in the bottom sediments can indicate the climatic changes in the Shira lake level in the Late Holocene.