We report about the Early Miocene Tagay fauna of Olkhon Island, the largest island of the Baikal Lake. The Tagay fauna is of high scientific importance because of the diversity of fishes, amphibians, lizards, snakes, turtles, manifold birds and mammals. The lithology, geochemistry and the fossil record along the Tagay-1 section allow reconstruction of various palaeoenvironments, i.e. open water, shallow lakes with adjacent wetlands, riverine woodlands, and also forested and dry habitats. The fossil record, lithology and geochemical sediment-analyses suggest a temperate palaeoclimate with short humid and dry periods. The small mammal record and the magnetic polarity pattern of the upper part of section Tagay-1 correlate with the subchrons C5Cn.2r – C5Cn.1r of Chron C5C and the late Burdigalian Stage of the Geologic Time Scale (GTS2000). The corresponding age range of the Tagay fauna is ~16.5 to ~16.3 Ma.

One of the most important fossil fauna localities in the Baikal region is the Tagay section. It is located on the shore of Tagay bay at the northwestern coast of Olkhon Island in the Baikal Lake and consists of two different exposures, Tagay-1 and Tagay-2. The Tagay-1 section exposes predominantly lake sediments of Miocene age and contains a faunal complex. The Tagay-2 section is composed of slope wash and subaerial sediments of Early Pleistocene (Calabrian?) age with remains of small mammals. A total of 95 samples for palaeomagnetic studies were taken in both sections. Magnetic susceptibility (MS), its frequency dependence (Fd) and anisotropy were measured from all samples. The stable component of the natural remanent magnetization (NRM) was obtained using stepwise alternating field (AF) demagnetization. The magnetic polarity pattern was constrained for the Tagay-1 section. It includes an extended zone of reversed polarity, complicated by three normal subzones of minor rank. Palaeontological data allow correlation of the Tagay-1 pattern with the magnetic chrons C5Dn to C5Cn.1n (late Burdigalian – early Langhian). Palaeomagnetic directions in the upper part of the Tagay-2 section are randomly distributed due to intensive slope-wash processes resulted in mechanical perturbation of the sediments. The lower part of Tagay-2 section demonstrates only reversed polarity, although the scatter of directions is quite large due to landsliding. This reversed interval may be correlated with the Matuyama chron between Cobb Mountain and Olduvai subchrons. Synchronous increase of MS and Fd values in palaeosols suggests a pedogenic (or “Chinese”) mechanism influencing magnetic properties of the Tagay-2 section under warm palaeoclimatic conditions.

The Ogurtsovo section, one of the key sections of the Ob’ region near Novosibirsk, has been comprehensively studied using a detailed geological description of deposits, granulometric and petromagnetic analyses. The combined methods allowed us not only to interpret the geologic structure of the Ogurtsovo section in terms of its facies and genesis but also to refine and supplement the Pleistocene geologic history of the region. Emphasis was placed upon relationships between granulometric and petromagnetic parameters. As a result, we have revealed regularities in the behavior of magnetic characteristics and their relationships as a function of granulometry in different lithogenetic types of deposits. On the example of this key section, criteria are proposed for distinguishing facies of the subaerial complex by analytical methods.

The results of paleomagnetic research of sediments from the Cenozoic key section of West Kamchatka at the Kvachina Bay are presented. In total, 152 samples collected from 121 stratigraphic levels of the 480-m-thick section are studied. The behavior of scalar magnetic parameters k, NRM, and Qn and magnetic anisotropy suggests that sedimentary rocks from the Kvachina Bay section were not subjected to significant deformations and substantial secondary alterations. A succession of 21 monopolar intervals combined into 10 magnetozones is identified within the section. Taking into account the correlation with reference levels of local zones based on diatoms, the correlation of recognized magnetozones with the Geomagnetic Polarity Time Scale (chrons C17 to C6) is outlined.

— Based on a detailed integrated petromagnetic, lithological, and micropaleontological study of the Mikhailovtsement reference section of the Moscow syneclise (Ryazan Region), the fluctuations...