Y/Ho Ratios in the Late Cenozoic Basalts from the Eastern Tuva, Russia: An ICP-MS Study with Enhanced Data Quality

A set of forty seven Late Cenozoic basaltic rocks from the Eastern Tuva (southern Siberia, Russia) have been studied by ICP-MS using In as an internal standard. Yttrium and Ho concentrations, determined along with other trace elements, varied systematically from one analytical run to another and covered the entire charge-and-radius-controlled field within the range 24 < Y/Ho < 34, so obscuring any geochemical interpretation. A correction procedure was therefore developed in which the Y/Ho ratios were recalculated using concentrations of these elements determined in international and in-house reference materials (BHVO-1, AGV-1, BIR-1 and U-94-5). Statistical analysis of the recalculated data set revealed two groups of samples not related by their genesis but rather by their respective analytical runs. Fourteen samples originally analysed in five different runs were then re-measured by the same instrument in peak-hopping mode using only specific mass peaks (m/z = 89, 115 and 165). All of these samples yielded Y/Ho ratios in a narrow range between 29 and 31, thus illustrating how analytical problems in the determination of Y and Ho by routine ICP-MS procedures can be overcome. Finally, a mean value of Y/Ho = 30.3 ± 1.1 (1s) was derived for the basaltic rocks of the Eastern Tuva. This is close to the value of 28.8 accepted for chondrites and for ocean island basalts. Despite the uniform Y/Ho ratio, the element concentrations in basaltic rocks from the Eastern Tuva show systematic enrichment in heavy rare earth elements and yttrium from the Miocene to the Quaternary.     

Determination of the excess density in a horizontal layered model

The inversion gravity problem formulated as follows is solved. The excess density in each layer of a fixed horizontal stratified model is a function of horizontal coordinates (σ(ξ, η)) approximated by a specially constructed function. The problem is to reconstruct the function σ = σ(ξ, η) from the external gravity field. If the geological model includes more than one layer, the problem is solved with the use of a set of reference points at which the sought function is given. Variations in a gravity anomaly with respect to the field at a fixed point are used in solving this problem.     

Inverse gravity problems for models composed of bodies of Sretenskii’s class

An inverse gravity problem is solved for a geological model consisting of bodies of Sretenskii’s class. The position of the middle plane is fixed for each body. It is required to determine the upper and lower boundaries of a body, which are described by analytical functions and are parameterized. The solution of the problem is illustrated by an example.     

Effect of the Geometric Characteristics of a Basin on the Space Structure of Forced Oscillations

By the method of mathematical simulation, we study the effect of changes in the width and depth of a ring-shaped basin with parabolic profile of the bottom on the space structure of waves generated by variations of atmospheric pressure periodic as a function of time. Our investigation is carried out under the assumptions of the linear theory of long waves with regard for the action of the Coriolis force. The structures of the profiles of liquid surface are compared for the cases of free and forced waves. We also establish the dependences of the period of atmospheric disturbances on the geometry of the basin for which the number of nodal points of the free-surface profile in the case of forced oscillations coincides with the number of nodal points of the profile of liquid surface in the case of free oscillations.     

Pleistocene mammal faunas of Eastern Europe

Systematic studies of the Pleistocene mammal assemblages of Eastern Europe have been carried out for more than a century, and they elucidated evolutionary changes and ascertained chronological sequence of the faunas. The available evidence on fossil mammals from Eastern Europe allows differentiation of 7 complexes of large mammals. These complexes represent 15 assemblages and their phases distinguished for small mammals. The appearance of new taxa of different rank provides the basis for identification of the principal stages in mammal evolution. Multi-disciplinary studies of fossil mammal localities have made it possible to correlate theriological data with the main events of the Pleistocene (such as glacials and interglacials) by comparison between geological, geochronological and palaeontological data.Interglacial and periglacial mammal faunas of different age have been defined on the basis of their structural characteristics and geographical distribution. Two types of mammal assemblages are recognised: zonal interglacial and periglacial assemblages specific to glacial periods. In the first type, each zonal assemblage is dominated by a single ecological group of mammals. A distinctive feature of the second type is the co-existence of animals belonging to different ecological groups and inhabiting different natural environments.     

The radial velocity variations of certainOii,Siiii, andNii lines — A confirmation of the shell ejection in the P cygni stellar wind

The radial velocity variations of the components of someOii, Siiii, andNii lines in P Cyg spectrum are investigated during the period 1981–1983. All data are analyzed in terms of a model which implies a multiple ejection of shells in the stellar wind. It is shown that the observed phenomenon is not periodic, but it occurs on a time-scale between 110 and 160 days with the most frequently observed length of the cycle of about 110 days. The shells move away from the star with an acceleration that is greater at low velocities than at high ones. The radial velocity variations ofOii, Siiii, andNii lines agree with these of hydrogen lines if we assume velocity and excitation condition differences inside the shell.     

Analysis of the Black-Sea climatic fields below the main pycnocline obtained on the basis of assimilation of the archival data on temperature and salinity in the numerical hydrodynamic model

We study model climatic temperature and salinity fields and the fields of currents in the 350–1000-m layer. The following specific features are revealed: Colder waters are observed in the regions with anticyclonic vorticity. At the same time, warmer waters are detected in the regions with cyclonic vorticity. This temperature effect can be explained by the elevation of temperature with depth below the main pycnocline. In the region of the Sevastopol anticyclone, at depths greater than 500 m, we observe a zone of cyclonic rotation of waters. Near the Caucasian coast, in the region of Gelendzhik, we reveal a narrow jet current existing at a depth of 350 m from March till July. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp.3–15, January–February, 2009.