Estimation of parameters of the flows forming sediment waves on the western slope of the middle caspian sea

By means of mathematical modeling, the parameters of flows forming sedimentary waves on the western slope of the Derbent basin were estimated. The height of these flows depends on the slope steepness and varies from 25 to 170 m to reach its maximum values at gentler slope areas. However, the flow rate is independent of the slope steepness and depends only on the concentration of sediment matter supplied by the flow. At the upper part of the slope (the flow starting), the rate amounts to 0.4–1.4 m/s, being almost halved at the depths where the sedimentary waves are damped. The present rates of near-bottom currents show pronounced seasonal differences, and their values are close to flow rates obtained by numerical modeling.     

Rock salt mass in the Paleoproterozoic sequence of the Onega trough in Karelia (from the Onega parametric well data)

A thick (200 m) rock salt mass covering Late Archean granitoids was exposed for the first time in the Early Proterozoic volcanogenic-sedimentary formations in the Onega trough of the east Baltic Shield by the Onega parametric well. The mineral composition of salts, their geochemical features, and the isotopic composition of carbonate carbon and oxygen have been studied. After fluid inclusions present in salts, their metamorphism temperature and isotopic composition of helium and argon were determined. The obtained results give evidence of the fact that rock salts and magnesites associated with them were formed in an evaporate basin with participation of deep crustal processes. The age of the underlying granitoids (2.716 ± 9 Ma) is determined using the Pb—Pb method.     

Statistical properties of the atmospheric turbulent boundary layer over steep surface waves

A new method of digital optical anemometry (Particle Image Velocimetry, PIV) of turbulent flows is suggested and implemented in the laboratory; it is based on the use of continuous laser radiation and high-speed video photography, providing continuous statistical ensembles of flow velocity fields. Application of the method to the study of wind field over waves has allowed us to perform, for the first time, direct measurements of velocity fields, averaged over turbulent pulsations induced by waves in the air flow. The experiments demonstrated that the velocity fields, averaged over the turbulent pulsations, are nonseparated even in the case of steep and breaking waves, when separation of the flow from the wave crests in the instantaneous fields is observed. Based on comparison with the experimental data, it is shown that the average wind fields over waves are described well quantitatively in the framework of semiempirical closure models of turbulence.     

Influence of the surface energy on the kinetics of chemical reactions of mineral nanoparticles

Doklady Earth Sciences -