Thermal anomalies associated with shallow gas hydrates in the K-2 mud volcano, Lake Baikal

Thermal measurements and hydrate mapping in the vicinity of the K-2 mud volcano in Lake Baikal have revealed a particular type of association of thermal anomalies (29–121?mW?m^–2) near hydrate-forming layers. Detailed coring within K-2 showed that hydrates are restricted to two distinct zones at sub-bottom depths exceeding 70–300?cm. Temperature data from stations with hydrate recovery and degassing features all display low thermal gradients. Otherwise, the thermal gradients within the mud volcano are generally increased. These findings imply a more complicated thermal regime than often assumed for mud volcanoes, with important roles for both fluids and hydrates. The coexistence of neighbouring low and high thermal anomalies is interpreted to result from discharging and recharging fluid activity, rather than hydrate thermodynamics. It is suggested that hydrates play a key role in controlling the fluid circulation pattern at an early stage. At a later stage, the inflow of undersaturated lake water would favour the dissolution of structure I hydrates and the formation of structure II hydrates, the latter having been observed on top of structure I hydrates in the K-2 mud volcano.     

Factors of 18O/16O fractionation in garnets: Evidence from calculations of isotope frequency shifts

Doklady Earth Sciences - Based on the density functional theory (DFT), frequency shifts of garnet end-members upon isotope substitutions (18O/16O, as well as “non-traditional” stable...     

Kinematical characteristics of the factorized velocity model

The factorized velocity model that incorporates both vertical heterogeneity and constant anisotropy is one of the complicated analytical models used in seismic data processing and interpretation. In this paper, I derive the analytic equations for offset, traveltime and relative geometrical spreading for the quasi‐compressional (qP‐) waves that can be used for modelling and inversion of the traveltime parameters. I show that the presence of anelliptic anisotropy usually dominates over the vertical heterogeneity with respect to the non‐hyperbolicity of the factorized velocity model.     

Crystallization of authigenic carbonates in mud volcanoes at Lake Baikal

This paper presents data on authigenic siderite first found in surface sediments from mud volcanoes in the Central (K-2) and Southern (Malen’kii) basins of Lake Baikal. Ca is the predominant cation, which substitutes Fe in the crystalline lattice of siderite. The enrichment of the carbonates in the ¹³C isotope (from +3.3 to +6.8‰ for the Malen’kii volcano and from +17.7 to +21.9‰ for K-2) results from the crystallization of the carbonates during methane generation via the bacterial destruction of organic matter (acetate). The overall depletion of the carbonates in ¹⁸O is mainly inherited from the isotopic composition of Baikal water.     

冰力学参数的超声波测试研究

利用非线性高能超声测试设备及超声波(纵波、横波)波速与物体力学参数的关系,对人造冰样进行了冰样力学参数(杨氏模量、泊松比、剪切模量、体积模量)随温度变化的研究。通过MATLAB进行所测数据曲线拟合,得到超声波波速在人造冰样中随温度的变化规律,进而由理论公式推导所测人造冰样力学参数随温度的变化规律。结果表明:冰样中超声波波速随温度降低而升高,冰样的杨氏模量、泊松比、剪切模量、体积模量也都随温度降低而升高。本研究有助于超声波检测法在冰样物理力学性质测量中的应用,为开展南极冰盖、海冰以及终年冻土等力学及流动特性研究提供理论模型和实验数据。     

Elemental diffusion and segregation processes in partially ionized solar plasma

Although diffusion is usually associated with equalizing of the chemical composition, the pressure and temperature gradients inside the Sun cause elemental diffusion segregation. While light hydrogen is flowing up to the solar envelope, helium and heavier elements are settling down to the core. The target of our simulation is an accurate estimation of the settling rate in solar plasma during the course of solar evolution. The rate of helium depletion in the envelope is a key parameter of the solar evolution and depends on position and conditions around the base of the convective mixing zone. The rate of heavy element settling is sensitive to the degree of ionization and interaction with the radiation flux. We estimate the effect of ion ionization on the settling rate for several heavy elements up to iron in the framework of the LTE assumption and the thermodynamic calculation according to SAHA-S EOS.     

Monitoring of the Arctic region: contribution of the Arkhangelsk seismic network

We evaluate the contribution of the Arkhangelsk seismic network to the recording of seismic events of the Arctic region. The evaluation is performed by means of the general analysis of the network seismic catalog, evaluation of the magnitude sensitivity, and comparative analysis of the Arkhangelsk network catalogs with NORSAR seismological data services and the Geophysical Service of the Russian Academy of Sciences. It is established that the Arkhangelsk network has a rather high sensitivity and records the intra-plate and inter-plate seismic activity in the Arctic Region. Due to the start of the seismic station operation on the Franz Josef Land Archipelago, there is a capability to record earthquakes, data on which are missing in the catalogs of well-known seismological data services.     

Plio-Pleistocene geological record and small mammal faunas, eastern shore of the Azov Sea, Southern European Russia

The shoreline of the Taganrog Gulf of the Azov Sea at the mouth of Don River provides a series of extended Upper Pliocene and Quaternary sections that have been actively studied in the last century. This extraglacial region had a complex sedimentary history combining subaerial aggradation with marine, fluvial, and deltaic sedimentation. The well-exposed stratigraphical sequence and abundant palaeontological record continuously attract geologists and highlight the region as one of international importance for the addressing of numerous problems of Late Pliocene and Quaternary stratigraphy and palaeogeography. Fossil mammalian faunas of the region include important Eurasian biostratigraphical markers such as Stenocranius ex gr. hintoni-gregaloides, Lagurini spp., and Mimomys savini. For many years, fossil remains of mammals provide decisive clues to the geological history of the region. Recent geological studies of reference sections have provided data on small mammals, palaeomagnetism and palaeogeographical reconstructions in the northeastern part of the Azovian Region. Mammalian assemblages indicate the presence of the Late Pliocene, late Early Pleistocene, Middle Pleistocene and Late Pleistocene levels and, in addition, provide a clear biostratigraphical context for the Early Middle Pleistocene transition.     

Verification of the multi-chamber model of radioactivity migration in reservoirs

A multi-chamber model of radioactivity migration in reservoirs was developed. It describes transport of radioactive substances in water and in bed sediments taking into account sorbtion of radionuclides on suspended particles. The model provides higher resolution than simplified chamber models do. At the same time, unlike complex two- or three-dimensional dynamic models, it does not require hard-to-obtain data such as detailed data on bathymetry, currents and winds. The model was included into the Sybilla program code that was developed in the framework of the Rosatom project called PRORYV. The model was verified against the observed data on the contamination of the Kiev Reservoir with ¹³⁷Cs in 1986.