APPLICATION OF THE L-CURVE METHOD IN DETERMINING THE QUASI-OPTIMAL REGULARIZATION PARAMETER FOR TWO-DIMENSIONAL INVERSION OF MAGNETOTELLURIC DATA AT THE BISHKEK GEODYNAMIC TEST SITE

APPLICATION OF THE L-CURVE METHOD IN DETERMINING THE QUASI-OPTIMAL REGULARIZATION PARAMETER FOR TWO-DIMENSIONAL INVERSION OF MAGNETOTELLURIC DATA AT THE BISHKEK GEODYNAMIC TEST SITE

DOES A SCIENTIST NEED A PERSONAL BIBLIOGRAPHY MANAGER?

A calculation of the amount of literature that should be processed by a scientist when conducting research in the field of Earth science has been made. An approximate estimate of the volume of literary sources processed by a scientist is 10000 works over 20 years. To work with such a large volume of literature it is necessary to use programs of bibliographic managers. The EndNote and Mendelay software are reviewed. The problems of such software packages and their advantages are discussed. The main disadvantage is the lack of support for long-term literature review work. In addition, there is insufficient support for hierarchical systems of semantic-intelligent relationship of articles with problems of the science of the Earth. The limitations of professional software of the bibliography managers forced to develop our own bibliographic manager. Algorithms of its operating bibliographic system, which realized implementation in the Access Microsoft program, are considered. The proposed algorithm can be used in other fields of science as well.

ECOLOGICAL-GEOCHEMICAL ASSESSMENT OF PETROLEUM HYDROCARBON CONTENT IN SOILS OF THE TAIGA ZONE OF THE LOWER AMUR REGION AND NORTHERN SAKHALIN (FAR EAST)

The background content of total petroleum hydrocarbons (TPH) in the most common soils of the Lower Amur region and Northern Sakhalin was determined. About 300 samples taken from the surface layers and horizons of 8 typical soil pedons were analyzed. The accumulative nature of TPH distribution in the soil profile was established, and their highest content was revealed in the organogenic horizons. The soils of eluvial landscapes (Podzols, Spodic Cambisols, Fulvic Cambisols) contain a smaller amount of TPH compared to the soils of accumulative landscapes (Histosols, Fluvisols). The maximum content of TPH was found in the Spodic Hyperalbic Technosols. The content of TPH in the anthropogenic abrasives of the Lower Amur region is estimated as acceptable, the level of pollution in the anthropogenic abrasives in Northern Sakhalin varies from low to very high. The results obtained on the background content of TPH can used for assessing of soils pollution and in conducting ecological monitoring studies.

EXPERIENCE OF COMPLEX MICROSEISMIC AND MAGNETOTELLURIC SOUNDING ON THE NORTHERN PART OF THE CENTRAL SIKHOTE-ALIN FAULT

We present the results of a study of the crustal structure of the northern part of the Central Sikhote-Alin Fault (CSAF) by methods of microseismic sounding (MSS) and magnetotelluric sounding (MTS). A geoelectric section based on MTS data and a section of relative velocities of P-waves according to MSS data were constructed and interpreted at a depth of up to 9 km and a length of 42 km. The main blocks, their boundaries, fault zones and some anomaly zones identified by microseismic and magnetotelluric sounding practically coincide. The CSAF zone is expressed by a narrow subvertical zone between high resistivity blocks. The data obtained indicate that the fault zone in the study area is impermeable. A similar structure was identified 6 km northwest of the CSAF zone, which can be traced to twice the depth (up to 20 km). It is concluded that the combination of microseismic and magnetotelluric sounding methods is promising for studying the structure of the Earth's crust in fault zones.

MORPHOLOGY OF THE PIIP SUBMARINE VOLCANO IN THE KOMANDORSKY BASIN BASED ON MULTIBEAM ECHOSOUNDER DATA

We analyzed the bathymetric data obtained during the cruises on the German research vessel “Sonne” using multibeam echosounders within the framework of the Russian-German projects KALMAR (cruise SO201-2, 2009) and BERING (cruise SO249-2, 2016) in the Komandorsky Basin of the Bering Sea. Detailed bathymetric maps of the Piip submarine volcano were constructed. New morphological features of its summit edifices and their age relations are described, hydrothermal activity confined to the edifices is localized, and all side cones and lava flows are mapped. Based on the flank cones and fissure lava flows alignments we determined the tectonic paleostress that existed at the time of their formation, presumably after the Late Miocene-Early Pliocene. It differs from the recent tectonic stress caused by right-lateral displacements along the Bering fault zone.

MINERAL WATERS OF THE AVACHINSKY DEPRESSION, KAMCHATKA

Saline waters (up to 22 g/l) were tapped by deep (to 3000 m) wells at the foot of active volcanoes Avachinsky and Koryaksky, within Avachinsky depression. Temperature of waters was ~ 60°C in the western part and cold in the eastern part, closer to the Pacific coast. In this paper we present the literature and our own data on chemical and isotopic composition of these waters. The waters are of the Na-Cl type with extremely low abundances of sulfate and magnesium, high concentration of calcium and surprisingly high concentration of strontium. The waters contain about 50 ml/l of gas where methane and nitrogen are main components (~ 70 vol% and 30 vol%, respectively) and also presents H2S (~ 30 ml/l) and very low concentrations of CO2 (< 0.5 vol%). The N2/Ar ratio, as a rule, is higher than the air ratio, i.e., the non-atmospheric nitrogen presents. We discuss the possible options of the water-rock interaction, responsible for the chemical composition of waters, and offer a conceptual model of the proposed basin of mineral waters that includes the distribution of deep temperatures, the location of the possible sources of heat mineralized solutions.

BEHAVIOR OF RARE EARTH ELEMENTS IN THE SOIL AND VEGETABLE COVER OF URBAN LANDSCAPES IN SOCHI

The geochemical regional specialization of the behavior of rare earth elements (REE) in the soils of Sochi, manifested in the predominance of REE of the middle group, has been established. The enrichment by the middle group of REE is inherited from the rocks (mainly clayey mudstones) of the territory. At the same time, the features of the distribution of REE, characteristic of natural soils, are not violated for soils formed under the conditions of technogenesis. This indicates that the pollution of urban soils is determined by a natural and technogenic factor. The sources of pollution are man-made sites and talus, which lack a soil-vegetation layer, including those recently formed during the preparation for the 2014 Winter Olympic Games and composed of the same material as the parent rocks, but significantly crushed and, accordingly, subject to active weathering. In mosses of the urban zone, in the eluvial landscape, the predominance of the middle group of REE is not observed. However, as we move down the slope, the REE distribution curve relative to the North American shale standardization becomes similar to the similar graph for soils and rocks. The relationship between the accumulation of elements in mosses, and in soils and underlying rocks is revealed when considering the features of fractionation of REE in mosses of the super-aquatic landscape.

TECTONIC STRUCTURE OF KERCH-TAMAN FOLD ZONE OF AZOV-KUBAN TROUGH

The nrotectonic structure of the Kerch-Taman folded zone, the southern deformed part of the Azov-Kuban piedmont trough, has a number of structural features and a history of deformation development. The authors divide the zone into five transverse segments, differing in the age of the main phase of folding. In the central Taman segment, folding is still going on, while in the framing segments, the main phases of folding took place in the Pliocene. In the peripheral segments, the main phase of folding is older - Early-Middle Miocene. The boundaries of the Kerch-Taman zone, as well as its youngest, the Taman segment, coincide with the transverse fault (fault-flexure) zones. It is shown that the southern frame of the Kerch-Taman folded zone is the continuation of the structures of the Crimean Mountains and the Northwestern Caucasus. The correlation of mud volcanism manifestations with tectonic elements of the Taman segment is noted to be ambiguous.

KLYUCHEVSKOY VOLCANO: NEW FLANK ERUPTION NAMED AFTER G.S. GORSHKOV, 2021 (KAMCHATKA)

February 18, 2021, a flank eruption started on the north-western slope of the Klyuchevskoy Volcano (Kamchatka, Russia). Cinder cone was formed at the altitude of 2 850 m above sea level, from which a lava flow was spreading north-west. Having moved 1.2 km downslope, the lava flow entered the Ehrmann Glacier, which resulted in the formation of huge mud-stone flows. The latter made their way further north-east along the Kruten’kaya River bed and reached the length of about 30 km. The eruption brought onto the surface high-aluminous basaltic andesites typical of the Klyuchevskoy Volcano. By March 21, the flank eruption ended. It has been named after G.S. Gorshkov, associate member of USSR Academy of Science, famous Russian volcanologist.

HEAVY CLASTIC MINERALS AS AN INDICATOR OF GEODYNAMIC SETTINGS OF ACCUMULATION AND PROVENANCE OF CRETACEOUS SEDIMENTS OF THE WEST SAKHALIN TERRANE

The article discusses the results of studying heavy clastic minerals from the Cretaceous sandy rocks of the West Sakhalin Terrane, and also presents their paleogeodynamic interpretation. It is shown that in terms of mineralogical and petrographic parameters, the terrane sandstones correspond to typical graywackes and are petrogenic rocks formed mainly by destruction of igneous rocks of the source areas. The sediments were found to contain both sialic, granite-metamorphic association minerals, and femic, formed by products of the destruction of basic and ultrabasic volcanic rocks. The interpretation of the entire set of data on the content, distribution and microchemical composition of heavy minerals was carried out by comparing them with minerals from older rocks and modern sediments accumulated in known geodynamic settings. The results obtained indicate that during the Cretaceous, sedimentation occurred along the continent-ocean boundary in a basin associated with large-scale left-lateral transform movements of the Izanagi Plate relative to the Eurasian continent. The source area that supplied clastic material to that basin combined a sialic landmass composed of granite-metamorphic and sedimentary rocks, a mature deeply dissected ensialic island arc, and fragments of accretion prisms, in the structure of which involved ophiolites.