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—Variations in the magnetic and geochemical properties of the sediments of Lake Bolshoe Yarovoe (Altai Territory) were studied. The data were derived from five core columns (up to 4.5 m long) covering a time interval of more than 8000 years. In addition, coercive spectra were obtained for 792 samples taken every 2 cm. Coercive spectra were then used to identify soft magnetic (10–15 mT) and hard magnetic (35–50 mT) components. The soft magnetic component is detrital, and the hard magnetic component is biogenic, which is confirmed by microscopic studies. Moreover, the samples contain micrometeorite particles. Variations in geochemical properties allow reconstruction of the environmental history of the lake. Sediments in the lower part of the section vary both in the content of ferrimagnetic components and in geochemical properties, which indicates a sharp environmental change between ~6100 and ~7600 years ago. Quasiperiodic alternation of warm (dry) and cool (humid) periods is observed higher in the section, between ~4100 and ~6100 years ago. The variations in the magnetic components are consistent with the environmental changes and can be used for the historical reconstruction.

The objective of this study is to provide a well-dated point for a future palaeosecular variation (PSV) reference curve for western Russia. For this purpose archaeomagnetic and magnetic property analyses were carried out on a pottery kiln unearthed at the UNESCO World Heritage site of ancient Bolgar, having a rather precise age dating. The archaeological context provided an age between 1340 and 1360 C.E. The characteristic remanence vector was determined through alternating field demagnetisation and Thellier-Thellier palaeointensity experiments. Some innovations were introduced regarding palaeointensity. The check testing the equality of blocking and unblocking temperature was redefined. This allowed waiving the commonly used additional zero-field cooling steps during the Thellier-Thellier experiment. Another innovation concerns the calculation of archaeointensity at structure level. A Bayesian approach was introduced for averaging individual specimen archaeointensities using a prior probability distribution of unknown uncertainties. Next, an additional prior probability distribution was used to correct for cooling rate effects. This resulted in a lower uncertainty compared to common practice and in eluding time consuming cooling rate experiments. The complex magnetic mineralogy consists of maghaemite, multi-domain haematite and Al-substituted haematite. Some samples contained also some non-stoichiometric magnetite. The magnetic mineralogy was determined through hysteresis loops, backfield and remanence decay curves, measurements of the frequency dependence of magnetic susceptibility and through low temperature magnetisation curves. Accompanying high-temperature thermomagnetic analyses revealed an excellent thermo-chemical stability of the studied specimens. Directions obtained from alternating field demagnetisation and those extracted from archaeointensity experiments are congruent and have low uncertainties. The obtained archaeomagnetic results are fairly in agreement with global geomagnetic field models and contemporary PSV data of the wider area. The geomagnetic field vector obtained for ancient Bolgar is of high quality, deserving thus its inclusion in a future PSV reference curve for European Russia.

Features of the sedimentation of lakes Bolshoi Kisegach and Turgoyak (Southern Urals) are described by studying the magnetic fractions and magnetic properties of bottom sediments via scanning electron microscopy. The magnetic fraction of lacustrine sediments consists of authigenic and allothigenic minerals.

Over the last few years, there has been an expansion of fallow lands in Russia due to issues in agricultural economics. Soils become fallow when left uncultivated for a time after successive crops. The recovery process depends on the duration of continuous arable farming in the area, soil type, area size and preferred land use methodology. Therefore, the importance of a comprehensive study of the processes occurring in fallow soils is reflected in their enormous expansion. In the course of soil formation, the transformation and migration of iron compounds change the magnetic susceptibility of soil. This suggests that magnetic susceptibility reflects the process of soil formation and may be considered a diagnostic indicator. This article presents the research results on the magnetic properties of fallow soils in Zelenodolsky district (Kazan). Samples of fallow sod-podzolic soils were used in this work. The magnetic properties of fallow soils were studied, and changes in the magnetic characteristics of fallow sod-podzolic soils were analyzed. The soil is characterized by the eluvial/illuvial type of profile patterns of magnetic susceptibility distribution. Evaluation of the contribution of the dia- /paramagnetic, superparamagnetic and ferromagnetic components from the coercive spectra shows that the increase in the magnetic susceptibility of sod-podzolic soils is due to the contribution of the ferromagnetic component.

Acquisition curves of isothermal remanent magnetization for 1057 samples of core KDP-01 from Lake Hovsgul (Mongolia) are decomposed into three endmembers using non-negative matrix factorization. The obtained mixing coefficients also decompose hysteresis loops, back-field, and strong-field thermomagnetic curves into their related endmember components. This proves that the endmembers represent different mineralogical fractions of the Lake Hovsgul sedimentary environment. The method used for unmixing offers a new possibility to apply rock magnetism in paleoecological and paleoclimatic studies. For Lake Hovsgul it indicates that a low-coercivity component with a co-varying paramagnetic phase represents a coarse-grained magnetite fraction from terrigenous influx probably via fluvial transport. A second component with coercivities close to 50∼mT is identified as a magnetite fraction related to magnetosomes of magnetotactic bacteria. The third component has coercivities near 85∼mT and is identified as greigite of biotic or abiotic origin common in suboxic/anoxic sediments. Significant positive correlations between variations of intensity of all three mineralogical components along the core are found. A rapid drop in all endmember concentrations by more than one order of magnitude at about 20∼m depth testifies to a major change of the environmental or geological conditions of Lake Hovsgul. It possibly is related to the onset of MIS∼10 marking the termination of arid climate conditions. Short intervals of high productivity are characterized by an abundance of magnetite magnetosomes and may highlight glacial-interglacial transition intervals. For the rest of the core greigite magnetization substantially exceeds that of magnetite, indicating a predominantly anoxic environment. This article is protected by copyright. All rights reserved.

We study the magnetic properties of virgin forest-steppe soils which formed on original vertical uniform unconsolidated parent material. In this work, profile samples of virgin dark-gray forest light loamy soil developed on a Permian (Kazanian stage) siltstone and virgin leached medium-thick fat light-loam chernozem developed on the Quaternary deluvial loam were used. Both soils are characterized by accumulative type of magnetic susceptibility and its components. The accumulative type refers to a profile where the maximum accumulation of substances takes place at the surface with a gradual fall in their content with depth. The calculation of frequency-dependent magnetic susceptibility (F-factor) shows that in studied soils F-factor reflect changes in their ferromagnetic fraction. In the humus part of the soil profile magnetic materials are present predominantly as fine mineral particles, and their content in the

The new method is suggested for separating ferromagnetic components in sediments through analyzing the coercivity spectra of the samples by the continuous wavelet transform with the Gaussian-based wavelet (MHAT). A total of 1056 samples of Lake Khuvsgul’s sediments (Mongolia) are studied. At least four groups of magnetic components are identified based on the analysis of their magnetization and remagnetization curves. Almost all samples are found to contain two components of bacterial origin which are represented by the assemblages of the interacting single-domain grains and differ by the grain compositions (magnetite and greigite). The applicability of the magnetic data for diagnosing magnetotactic bacteria in sediments and building paleoecological and paleoclimatic reconstructions is demonstrated.