Relationship of the Long-Period Free Oscillations of the Earth with Atmospheric Processes

Doklady Earth Sciences - Based on the five-year record of the superconducting gravimeter in Strasburg (48.6° N, 7.7° E), the correlation is calculated between the long-period free...     

New data on sedimentation and biostratigraphy of ancient and New Azov Deposits (Sea of Azov)

Applying the methods of absolute geochronology and lithology, it has been established that the average sedimentation rate in the Sea of Azov over the last 6000 years (Ancient and New Azov times) varied from 0.2 to 2.0 mm/year. Its minimum values are confined to transit and sediment-starved zones coinciding with the directions of the main marine currents. It has been indicated that changes in the water level of the Sea of Azov occur with lag relative to landscape–climate phases. The obtained data confirm the relation between marine and terrestrial processes occurring in the Sea of Azov region: transgressive phases are preceded by general humidification in adjacent regions, while regressive phases correlate with climate aridization. The biostratigraphic analysis of the Holocene sections examined reveals the unstable behavior of the sea level during their formation. The results of diatom analysis confirm development of the Phanagoria and Korsun Regressions and Nymphea Transgression. Frequent fluctuations of the Sea of Azov the level determined the rhythmical structure of the sedimentary sequence saturated with autochthonous and allochthonous organic matter.     

Dynamic Mode of the Azov Sea in Conditions of Salinization

Doklady Earth Sciences - We studied the currents mode of the Azov Sea on the basis of instrumental measurements of R/V Deneb in 2018 and 2019. Using ADCP current meters, water exchange...     

New Results on the History of the Sea of Azov in the Holocene

Doklady Earth Sciences - The results of comprehensive studies of bottom sediments and coastal transects in the Sea of Azov, obtained in recent years, have been analyzed. The changes in natural...     

Dynamics and Thermohaline Structure in the Contact Zones of the Azov Sea

Doklady Earth Sciences - The results of instrumental measurements of the thermohaline structure and currents in the areas where fresh river waters (Taganrog Bay and Temryuk Bay) and the Black Sea...     

Fold-thrust dislocations in sedimentary cover of the Sea of Azov

As follows from geological and geophysical data, tectonic deformations formed under lateral compression are widespread in the sedimentary cover at the bottom of the Sea of Azov. Fold-thrust dislocations are established in the North Azov Trough on the southern slope of the Ukrainian Shield, in the Azov Swell of the young Scythian Plate, and in the Indol-Kuban Foredeep. The transregional Main Azov Thrust Fault and smaller thrust faults of listric morphology tens of kilometers in extent are known. Asymmetric anticlines are related to their fronts. In plan view, the crests of these anticlines are displaced down the dip of the controlling faults. Folds and thrusts developed in pulsatory manner in the regime of periodically acting tangential compression are recorded in the thickness of the plate complex and stratigraphic and angular unconformities. Some of these dislocations are active and accompanied by anomalously high formation pressure, temperature and hydrochemical anomalies, tectonic brecciation, and mud volcanoes.     

库水位涨落对库岸滑坡稳定性的影响

三峡水库正常蓄水后, 库水位在175~145m之间周期性波动, 滑坡地下水渗流状态将会发生较大的改变, 可能导致滑坡失稳.因此, 研究库水位周期性波动下滑坡的稳定性具有十分重要的意义.提出了土水特征曲线的多项式约束优化模型和采用饱和-非饱和渗流数值模型.以赵树岭滑坡为例, 利用有限元数值计算了库水位在175~145m之间波动下地下水渗流场, 将计算得到的孔隙水压力用于滑坡的极限平衡分析, 探讨了库水位上升和下降对库岸滑坡稳定性的影响.研究表明: 多项式优化模型可以很好地拟合非饱和土的土水特征曲线; 库水位上升时滑坡稳定性系数总体逐渐增大, 库水位下降时滑坡稳定性系数总体逐渐减小; 无论是库水位上升还是下降到库水位155m时, 其稳定性系数最小; 同一库水位下, 库水位上升时的稳定性系数比下降时的稳定性系数大.      

库水位变化对库岸边坡稳定性的影响

在假定坡体孔隙水水位为水平线且不考虑渗透作用影响的基础上,基于极限平衡法考察了水位上升及下降的快慢对边坡安全系数的影响。对比计算表明:在水位缓慢变化即坡体内外水位线等高的条件下,边坡的安全系数随着水位坡高比的增大先略减小后急剧增大,且在水位坡高比为0.3处取得最小值,在边坡完全淹没于水中时取得最大值。当边坡完全淹没于水中后,水位高于坡顶的多少对边坡安全系数没有影响;在水位骤降或陡升条件下,相同库水位对应的边坡安全系数基本上均小于水位缓慢变化情况下的安全系数,故工程实际中无论是排水还是蓄水,都应尽量保持水位缓慢变化,这样才能使边坡处于较安全的状态。     

Late holocene climate changes in the Sea of Azov region

The results of paleoclimatic reconstructions made with the help of the information-statistical method developed by V.A. Klimanov based on palynological data from the Sea of Azov bottom sediments. For the period of the last 3000 years, four phases of warm and dry climates and three phases of relatively cool and humid climates were identified. The latter phases were characterized by wider expansion of tree vegetation in the region around the Sea of Azov. The range of mean annual temperatures between warmer and cooler intervals was about 4°C.     

Modern diversity of the macroalgae of the Sea of Azov,the Black Sea,and the Caspian Sea

Currently, the species list of the macroalgae (excluding Charales) inhabiting the southern seas of Russia includes 388 species, specifically, 362 species in the Black Sea, 46 species in the Sea of Azov, and 70 species in the Caspian Sea. The species list has been increased by approximately 30% (96 species, most of them are registered in the Black Sea), compared to the data obtained 30 years ago. The green and red macroalgae of warm-water Mediterranean and tropical origin (Ceramium, Polysiphonia, Laurencia, Ulva, and Chaetomorpha) and brown algae (Sargassum and Cytoseira) were the key invaders. Nowadays the maximal species diversity is found on the Crimean coast and the Turkish coast of the Black Sea; and the species list of the Turkish coast differs significantly from all the other studied sites of the Black Sea. The number of the algae of the warm-water complex increased the most in 1990s–2000s in the Black Sea; species of boreal-tropical and subtropical origin dominate. However, such a tendency was not observed in the Sea of Azov and in the Caspian Sea, but expansion of the habitats of the brackish green algae has been registered.     

Impact of atmospheric circulation fluctuations on the zoobenthos dynamics in the Sea of Azov

The impact of atmospheric circulation fluctuations (Vangengeim’s classification) on the zoobenthos dynamics in the Sea of Azov was studied. The “western” circulation processes lead to zoobenthos biomass decrease, and the opposite pattern was observed when “eastern” circulation processes prevail. A quasiperiodicity with 3–7 to 10–15 year cycles is revealed for the zoobenthos biomass dynamics. These changes are closely connected with the climatically induced increase of the zoobenthos biomass in the Sea of Azov.     

New data on the sedimentation rate in the Sea of Azov in the Late Holocene

The sedimentation rates in the Sea of Azov for the period of the last 2000 years (Late Azov stage) were studied by methods of absolute geochronology, lithology, and biostratigraphy. The average sedimentation rate of the Late Azov deposits varied from 0.4–0.8 to 1.5–2.0 mm per year. It reached as much as 4.0–6.0 mm per year in the areas close to the sharp coasts and was defined by the area geomorphology. The scheme of the lithological transects, sedimentation rates, and absolute age of the sediments is presented. The palaeoecology peculiarities of deposit accumulation during the Late Azov stage are described from the diatom and spore-pollen analyses.