Unique phenomenon of the accumulation of <Emphasis Type="Italic">terrestrial</Emphasis> metal iron particles in lacustrine deposits: Zhombolok volcanic region,East Sayan

The native iron particles that were previously detected by thermomagnetic and microprobe analyses in the sediments of different age in many regions of the world are of extraterrestrial origin. The similarity in the compositions, grain shapes, and sizes observed in the extraterrestrial and terrestrial particles of native iron testifies to the common production conditions of iron particles during the formation of planets. In this paper, the single finding of terrestrial iron in the lacustrine sediments of the Zhombolok volcanic region, East Sayan, is discussed. The uniqueness of the results indicates that the spatial distribution of the particles of native iron is limited to a fairly narrow area around their source—volcanic eruption or/and the fall of a large meteorite.     

Hysteresis characteristics of subaeral deposits in the Baikal region

The results of rock magnetic studies in four subaeral cis-Baikalian sections of different ages and geneses are described in detail. The similarities and distinctions in the formation of the magnetic properties of the sediments are established based on the analysis of the magnetic hysteresis parameters. The mechanisms responsible for the dissimilarity of the magnetic characteristics of the rocks in the different sections are identified. The variations in the composition, concentration, and particle size of the grains of magnetic fraction as a function of climate, geomorphologic factors, and volcanism are demonstrated.     

Rock magnetism and magnetostratigraphy of the loess-sol series of Ukraine (Roksolany,Boyanychi, and Korshev sections)

The results of the rock magnetic and paleomagnetic studies for the Quaternary loess-sol deposits of Ukraine are reported. The magnetic properties of the rocks composing the sections in the Pre-Black-Sea Depression (Roksolany) and Volyn Upland (Boyanychi and Korshev) are compared. Based on the highly precise measurements by modern instruments, the primary magnetization component is isolated in the rocks and its polarity is reliably determined in both the loess and soil horizons. The position of the Matuyama–Brunhes boundary in the Roksolany section is determined at a depth of 46.6 m at the contact of the Lubenskii and Martonoshskii soil horizons. This is consistent with the present-day notions of the group of Ukrainian scientists about the Quaternary stratigraphy of the south of Ukraine and inconsistent with the previous results that placed this boundary at a depth of 34 m in loesses above the PK₇ level.     

U–Th age of the Kazantsevo (MIS 5) Horizon of the Upper Neopleistocene Ust Oda reference section,Baikal Region

For the first time, the organic sediments of the Kazantsevo Horizon (Baikal Region) were characterized geochronometrically. The ²³⁰Th/U age of the buried gyttias from the Upper Neopleistocene Ust Oda stratotypical section on the Kitoi River was determined using a new version of isochronous approximation. The assemblage of all the ²³⁰Th/U age data, which were obtained taking into account the errors in the entire range from 136 to 86 kyr, indicates that most likely gyttia age is 115–104 kyr (MIS 5d). Thus, the paleontological conclusions on the Kazantsevo age of the Ust Oda Formation with buried gyttias are confirmed. Our geochronometric data supplement and make more reliable the age model of the formation of sedimentary rocks of the Ust Oda section.     

Katabatic glacier wind

Doklady Earth Sciences -     

Energetic analysis of global topography

Diagrams of the various distributions of the potential energy of the continental and oceanic-bottom topography as a quantitative indices of energy consumption by tectonic processes have been calculated and plotted for the first time on the basis of high-resolution ETOPO 2′ digital data on a 2′ × 2 ′ uniform network with height intervals of 100 m. The potential energy of the continents and oceanic bottom is mainly stored in mountainous regions of Asia and South America with an anomalous type of energy distribution and in mid-oceanic ridges, respectively. The topography of the oceanic bottom bears five times more energy than the continental topography. With allowance for the isostatic compensation of denudation, the bulk reserve of the potential energy of the global topography is estimated at 10³³ erg, a value which amounts to only an insignificant fraction of other items in the energetic budget of the Earth. Fifty percent of this energy has been gained over the last 70 Ma. Currently, the rate of accumulation of the potential energy of the topography is 10²⁵ erg/yr, i.e., 1000 times less than the bulk geothermal flow and 10 times less than energy released by all earthquakes during a year. So far, there are no grounds to bind the potential energy of the Earth’s topography with a specific source.     

Bathymetry of the seas in the West Pacific transition zone based on the ETOPO 2′ digital data

New results of the statistical analysis of the depth distribution in the seas of the West Pacific transition zone based on the ETOPO 2′ digital data are presented in the form of bathygraphic and bathymetric curves with a 100 m depth interval for the entire zone, individual seas, and 5-degree latitudinal bands (transects). The depth distributions show wide diversity in the seas at high correlation over the transects. The new average depths of the seas calculated in this work are higher than those reported in previous works.