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Determination of the soil weathering rate plays an important role in estimation of the stability of terrestrial ecosystems because weathering is the major source of matter in ecosystem. This work was aimed at elaborating a technique for comparative evaluation of the rates of weathering in small areas making up a single landscape-geochemical system. The studies were carried out in the basin of the Pereemnaya River. The present-day and the average historical weathering rates were estimated. Data on the ion runoff show that the contributions of different areas of the water catchment basin are unequal. For the total content of Ca²⁺, Mg²⁺, K⁺, and Na⁺, the weathering rates calculated using the balance method vary from 1.1 to 5.4 keq·ha^-1·yr^-1. The weathering rates calculated from the isotopic composition of Sr are nearly the same (1.6-5.2 keq

This paper reports new data on geological structure, palynostratigraphy, and paleomagnetism obtained from key BH-9 as well as from BH-2, BH-6, and BH-13 drilled in the south of the Novosibirsk Region. The rock lithology has been described to follow the stratigraphic sequence. The question on recognition of the Upper Cretaceous is discussed. Zonal complexes of dinocysts, spores, and pollen are characterized. The marine deposits date from the Paleocene and Miocene, and the continental ones, from the Oligocene and Miocene. The data on microphytofossils confirm the recurrent character of development of the Tavda sea basin in the late Middle-Late Eocene. Cysts of dinoflagellates of the genus Pseudokomewuia were established for the first time in the Upper Oligocene sediments (Turtas lake-sea), which suggested a connection of the Turtas basin with southern seas through the Turgai strait at the beginning of Zhuravka time. The range of occurrence of dinocysts is bordered south of 55

Results of petro- and geochemical study of traps in the basin of the Morkoka-Markharata River are reported. The traps are compared with Permo-Triassic basites from other regions of the Siberian Platform. Permo-Triassic trap intrusions in the eastern Tunguska syneclise are made up of three petrochemically different types of basic melts. They successively intruded during the same tectonomagmatic cycle. Each of the intrusive groups has its proper geochemical specifics originated during the magma generation and preserved throughout evolutionary transformations up to the emplacement of magma in a modern chamber. This specifics does not depend on the volume of intruded melt, scale of intrachamber differentiation in the intrusions, character of transformation of magma during its deep-level fractionation on the path to a modern chamber, and position of the intrusions relative to magma control zones within the Tunguska syneclise.

Choice of observation sites is of key importance for understanding geodynamic processes and related phenomena, especially earthquakes, as it has been found out through three decades of investigation into preseismic, coseismic, and postseismic dynamic and nonlinear effects. Junctions of trans-lithospheric active faults are extremely heterogeneous zones in the multiphase polydisperse system of the lithosphere. These zones, marked by specific nonlinear and dynamic properties, build up the greatest elastic strain and are thus the least stable thermodynamic elements highly sensitive to external physical effects, mainly associated with regional stress variations. The sensitive local lithospheric zones with their ability to accumulate, redistribute, and release various types of energy were called sensitive energy active points (SEAP). Monitoring at the Kajaran SEAP station in an active seismic region of southern Armenia showed compression effects related to all earthquakes within the Arabia/Eurasia collision zone, irrespective of their epicentral distances.

The relationship between layer and apparent reflection velocities obtained for a layer much thinner than the overlying in a 2D transversely isotropic medium can be used to plot offset dependence of effective ray velocity indicative of anisotropy type. This approach, called point inversion, is based on the properties of two rays which are reflected from the layer top and bottom and connect a single source-receiver pair. Point inversion is applied, after constraining the layer thickness, to obtain the indicator function of ray velocity and then to find the horizontal velocity and anisotropy in each layer. Processing of seismoacoustic radio buoy data acquired in marine sediments and numerical modeling show up to 16 percent anisotropy of type 2.

The study further details the formation and subformation stratigraphy of the Silurian section of the northwestern Siberian Platform in terms of the distribution of ecosystems correlated to chronozones. A lithified fossil ecosystem is represented by a genetically uniform dominant lithology and the hosted fossil biocenosis, which together make an ecostratigraphic unit (lithified biocenosis or biolithocenosis). The ecostratigraphic structure of Silurian sediments in the region is described according to the ages, locations, and dominant lithologies and fossil fauna assemblages of 105 units distinguished in the section.

Principles of medium-scale neotectonic mapping have been considered by the example of junction of the old Siberian Platform and young West Siberian Plate. Instead of neotectonic systems commonly used as a basic unit in teotectonic mapping, the fault-block structure of terranes and its morphotectonic analysis are proposed. The role of faults in the formation of contrasting relief features increases in the transition from global through regional to local level of structures. Being a derivative of neotectonic movements, the relief mirrors neotectonic structures. The more contrasting relief, the younger it is and the faster neotectonic movements are. A schematic succession of neotectonic analysis is as follows: morphotectonic analysis of relief - detailed mapping of network of fault structures - recognition and ranking of neotectonic blocks - characteristic of neotectonic relief within the blocks and estimation of its contrast - calculation of velocities of neotectonic movements - construction of a neotectonic map.At the junction of the Siberian Platform and West Siberian Plate in the lower reaches of the Kan River, the neotectonic structure is controlled by the Baikal-Yenisei fault zone, represented by a dense network of submeridional reverse-fault-nappe structures having distinct traces of Pleistocene rejuvenation. The zone of the Baikal-Yenisei fault is crossed by young diagonal strike-slip structures, of which the northwestern ones are dextral, and northeastern, sinistral.This system of faults cuts out a series of macro- and microblocks. West of the Baikal-Yenisei fault, the block structures tend to subside, and east of it, they tend to rise. The velocities of subsiding and rising are quite close, which is inferred from the compensated filling of basins with young sediments in the immediate vicinity of the rising block. Vertical and horizontal displacements along young faults have been recognized for the study area, their kinematic type has been ascertained, and the character of lithosphere blocking has been defined as a function of the type of its stress state. It has been established that the territory is most fragmented where fields of compressive and shear stresses are superposed.

Natural bitumens are widespread in the sedimentary cover of the Yakutian diamond province. They occur within a broad stratigraphic range and differ in size and character. A number of oil and gas fields have been discovered in the province. Numerous natural bitumen occurrences are found in kimberlite pipes and host rocks. Geochemical characteristics of the samples taken from different sites in and off the body of kimberlite pipe - kimberlite, xenolith, host rocks - display a rather intricate pattern. Their composition can be considered as a result of superposition of two processes: thermal destruction and deasphaltization of oils. The calculated temperatures of host rock heating and the time of cooling of kimberlite pipe suggest weak thermal destruction in both xenoliths and host rocks.

Increasingly more attention is paid to the problem of hydrocarbon production from reservoirs with a complex geologic structure. In particular, these beds can be of lenticular structure, with separate sandstone lenses distributed in a shale matrix. A stochastic approach seems to be quite natural to describe such deposits.The probabilistic description of a system of lenses involves such parameters as: shape and size of deposit, shape and size of lens, probability density of distribution of lenses, and number of lenses in the study area.Mathematical tools have been devised to describe relationships between a system of lenses and a system of wells. Formulas for the probabilities of the relevant events have been derived and used for solving an inverse problem. The parameters of the system of lenses are numerically estimated by the method of maximum likelihood using data of exploratory drilling.Some results of practical significance have been obtained. The proposed approach has been used to analyze the uncertainty and risk of well location and to estimate the effectiveness of horizontal well drilling and hydraulic fracturing in lenticular reservoirs. The described approach is illustrated by its application to the estimation of oil field parameters. An example was a field in West Siberia.

The northern zone of West Sayan, made up of Vendian, Early Cambrian, and Middle Cambrian volcanosedimentary rocks, is a fragment of a large island-arc system on the southwestern periphery of the Siberian craton. The specifics of this zone is a wide occurrence of plagiogranitoids of the Maina tonalite-plagiogranite complex, which are spatially associated only with the deposits of the Early Cambrian Nizhny (Lower) Monok Formation.By now, the nature and age of the Maina plagiogranites have been debatable because of the absence of reliable isotope-geochronological data and drastic diversity of opinions regarding the nature of pebble of plagiogranitoids from conglomerates of the Lower and Middle Cambrian volcanosedimentary deposits.Plagiogranitoids of the Maina complex were compared with plagiogranitoid pebble from the lower beds of the Verkhny (Upper) Monok Formation, which contain paleontologic remains of Early Cambrian age. It has been established that some pebble varieties do not differ in petrographic, petrochemical, and trace-element compositions from plagiogranites of the Yenisei and Tabat plutons. Results of U-Pb and Ar-Ar isotope dating of the plagiogranitoids point to their Early Cambrian age (523.8±2.1 Ma). Isotope-geochemical modeling of the composition of the source of plagiogranites showed that their primary melts were produced from metabasic substrates corresponding in trace-element composition to island-arc tholeiitic basalts at low (<10 kbar) pressures.