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Studies of primary multiphase silicate inclusions in accessory Cr-spinels from the fine-grained dunites of the Nizhnii Tagil Pt-bearing massif reveal their similarity to melt inclusions trapped by chromite during its growth. The analyzed Cr-spinels with multiphase silicate inclusions differ in composition from ore chromites of the same massif and from chromites (with melt inclusions) from ultramafic oceanic complexes but are similar to Cr-spinels in dunites from Pt-bearing alkaline ultramafic massifs (Konder and Inagli). According to petro- and geochemical data on heated multiphase silicate inclusions, the studied Cr-spinels crystallized with the participation of subalkalic picrobasaltic melts similar to the magmas of the Konder Pt-bearing massif and having almost the same chemical composition as tylaites. The differences between the compositions of olivines formed within the multiphase silicate inclusions and of the rock-forming minerals show that the studied Cr-spinels formed from an intercumulus liquid melt in the olivine crystal interstices during the cumulate crystallization of most of the Nizhnii Tagil massif dunites in the intrusive chamber. Numerical modeling based on the compositions of heated multiphase silicate inclusions in accessory Cr-spinels demonstrates that olivines and Cr-spinels from the studied dunites crystallized at 1430 to 1310 ºC and then olivine formation continued to 1280 ºC during the evolution of melts.

We present results of investigation of the trace-element (REE, HFSE) and Hf isotope compositions and U-Pb age of single zircons crystallized from alkaline-carbonatite magmas of the Ilmeny-Vishnevogorsky complex (IVC) (Urals, Russia). It has been established that the geochemical characteristics of the early zircon (U-Pb age is 430-410 Ma) from alkaline rocks and carbonatites of this complex are determined mainly by the magmatic evolution of parental fluid-saturated alkaline-carbonatite melts and, to a large extent, are associated with the cocrystallization of zircon and uranium rare-metal minerals (gatchettolite and pyrochlore) at the final stages of the magmatic-system activity. Early IVC zircons have a moderately depleted Hf isotope composition (εHf from +11.3 to +4.7), confirming the mantle nature of the magma source and indicating the participation of DM-like and enriched-source (probably, lower-crust component) substances in the magma generation. The considerable variations in the initial Hf isotope composition of the early zircons testify to the multistage zircon crystallization involving new portions of melts with different isotope compositions related to mixing of substances at their source. Late IVC zircons (250-350 Ma) have strongly disturbed «rejuvenated» isotope systems and a geochemical composition different from that of the magmatic zircons. They formed apparently at the metamorphic stage without a substantial input of additional material.

We present nomenclature and geochemical classification of Paleoproterozoic LILE-enriched high-Mg low-Ti mafic-granitoid rocks of the eastern margin of the Sarmatia paleocontinent and substantiate their tectonic position. Two differentiated rock series are recognized: 1) biotite-orthopyroxene melanorite-quartz-meladiorite-melagranodiorite and 2) hornblende-biotite quartz-diorite-tonalite-granodiorite. Both series correspond in chemical composition to calc-alkalic gabbro-diorites, diorites, tonalites, and granodiorites. As follows fr om their mineralogical and geochemical compositions, these are norite-diorite rocks (intrusive analogs of boninites) (SiO2 = 52-65 wt.%, MgO = 5-20 wt.%, TiO2 = 0.2-0.8 wt.%) and high-Mg granitoids (SiO2 = 60-70 wt.%, Na2O/K2O = 0.65-1.33, MgO = 3.23-7.4 wt.%, K2O = 1.9-4.0 wt.%), respectively. Their high Mg# values (67-87) and Cr contents (>100 ppm), on the one hand, and their isotope-geochemical characteristics similar to those of the host metaterrigenous rocks, the magma enrichment in LILE, and the presence of Ni sulfide ores with a predominance of light sulfur isotopes, on the other, testify to crustal contamination of mantle magmas. The rock series are nearly of the same age and belong to the same magmatic system, wh ere high-Mg granitoids are differentiates of parental high-Mg (boninite-like) norite-dioritic magma. This is confirmed by a gradual increase in SiO2 and K2O contents and a decrease in Mg# and Ni, Co, V, and Cr contents in the sequence from norites to granodiorites and by the facies and phase relationships between the series. Intrusion of rocks took place at shallow depths after low-temperature metamorphism and folding under postcollisional collapse of the East Sarmatian orogen.

Several sections have been studied to understand the distribution and interrelation of basic genetic types of Quaternary deposits in the Uimon basin and adjacent area. The OSL date of 101 ± 10 ka from the glaciolacustrine terrace on the northeastern rim of the basin corresponds to the cool substage of MIS 5. The glaciolacustrine sediments of the northern rim are covered with widespread diamictic flows of the outburst draining of the ice-dammed lake. The diamicts are overlain by a subaerial complex of three loesses and three paleosoils. From the OSL loess dates in the range of 43 to 49 ka we infer that the complex formed from the early MIS 3 through the Holocene. This is also supported by radiocarbon dates from fluvial deposits incised into the glaciolacustrine terrace and into megaflood sediments of the final draining of the last paleolake. The OSL dates in the range of 78 to 89 ka from alluvial sediments indicate that postglacial downcutting of the present-day Katun’ valley probably started just after MIS 5. The discrepancy between the beryllium dates from dropstones and Holocene TL-dates of the Katun’ valley floods ranging from 23 to 6 ka can be explained if the younger floods are related to the draining of moraine- and landslide-dammed rather than ice-dammed lakes. The younger floods, though being less voluminous than the glacial megafloods, were capable to produce giant ripple marks.

High-resolution stratigraphic analysis of the lower second member of the Shahejie Formation of the W79 Block of Bohai Bay Basin, China, has revealed that the study area, previously interpreted as a shallow water delta system, actually originated mainly in a subaerial setting with a distributive pattern. Depositional systems of the distributive fluvial complex (DFC) have been recognized. The regional correlation of the lithofacies within the different depositional systems has led to a high-resolution-stratigraphic framework of two long-term base level cycles, six middle-term base level cycles, and more than 58 short-term base level cycles. Sequence boundary SB1 marks the top of the target interval and is characterized by thick and continuous mudstone overlying sand-rich channel sediments. Sequence boundary SB2 marks the bottom of the target interval and is characterized by stably distributed shales between sand-rich sediments. The base-level fluctuation has a strong tectonic component consistent with the regional tectonic setting; during the active subsidence stage, base-level rising semi-cycles were recorded in the strata, and during the relatively stable stage, base-level falling semi-cycles were recorded.

The pore space of reservoir rocks has a lot of active centers capable to form different types of bonds (from hydrogen to chemical). Therefore, almost any hydrocarbon can be adsorbed to a particular extent on the internal pore surface and form an adsorbed layer, which has a definite spatial configuration and makes contact with a certain part of the rock surface. Study of gas condensate reservoirs brings up the question of the composition of adsorbed hydrocarbons. The properties of such hydrocarbons in many giant gas condensate fields are of special interest as these compounds can serve as an additional source of resources after production of mobile-gas reserves. The performed study of gas condensate reservoirs of the Karachaganak, Astrakhan, and Yamburg fields has shown that their adsorbed hydrocarbons (adsorbed oil) have polar components with sulfur and oxygen atoms.

This study continues the work by Mikhail Gzovsky on geological (tectonophysical) criteria for seismic risk. It is suggested to perform seismic-risk zoning according to parameters of normal and shear stresses on fault planes converted from results of tectonophysical stress reconstructions. The approach requires the knowledge of both dip and strike of the respective fault segments. Slip geometry is estimated from stress tensor, assuming that it is directed along shear stress. The suggested approach is applied to faults in the northern Tien Shan, and the current stress parameters are reconstructed using source mechanisms of catalogued earthquakes recorded by the KNET seismological network of the RAS Science Station in Bishkek. Stress modeling is performed by the method of cataclastic analysis providing constraints on stress ellipsoids, as well as on relations between the spherical and deviatoric components of the stress tensor. Plotted on the Mohr diagram, the fault stress points allow estimating whether the respective fault segments are close to the critical state (brittle failure). The suggested seismic-risk zoning of faults in the northern Tien Shan reveals up to 25 km long hazardous fault segments.

Gas hydrates in sediments can dissociate on heating, which causes a characteristic change in temperature over time. This can be used to detect hydrates and estimate their content. The geothermal method for gas hydrate prospecting consists in obtaining thermograms and defining regularities related to the presence of gas hydrates in the medium. The aim of this study was a quantitative estimation of hydrate content in sediments, based on data from repeated measurements of the temperature of a linear heat source (needle probe). The power of the source is chosen so that hydrate does not decompose in the first measurement but decomposes in the second. Afterward, we solve the optimization inverse problem of determination of the model parameters, one of which is a hydrate content. Experimental data on heating of the laboratory samples are processed, and hydrate contents are obtained with an accuracy of 30%. These values agree with independent estimates. The analytical solution of the axially symmetric problem of gas hydrate dissociation, based on the solution of the Stefan problem, is applied as a mathematical model for hydrate heating and decomposition in the sample.

The data obtained in 1995-2014 in the areas of the Sulakskaya and Turalinskaya lagoons (Dagestan, the western coast of the Middle Caspian) were summarized. The lagoons are located in a “bottleneck”, a narrow migration corridor traversed by one of the largest migration routes of trans-Palearctic species in Russia. This route is a part of the West Siberian-East African migration range. The migration traffic and territorial localization of the Laridae populations, participating in the total migratory flow along the western coast of the Caspian Sea were determined. The present-day migratory range of Laridae covering the area from Western Europe to Lake Baikal and Western India was specified. It was determined that Dagestan is crossed not by one but two independent and stable migration flows of Laridae, flying across the transit region in different migration routes but at the same periods of time. Three types of migration intensity of Laridae across the study area were defined: weak, average and mass migration. Both spring and autumn migration includes 5 peaks of migration activity (migratory waves). Timing, taxonomical composition and abundance of Laridae species vary for each degree type of migratory waves. Key determinants of migratory wave intensities are abundance of migratory populations and weather conditions of the year. It was proved that over the last 5-7 years there has been a steady decrease in abundance of some Laridae species on the western coast of the Middle Caspian. This decrease was determined by a set of factors acting across the whole migration range. Decrease in abundance of migratory Laridae leads to blurring of the boundaries between migratory waves and migration intensity. It causes changes in migration routes of some Laridae populations which now have shifted from traditional wintering grounds along the western coast of the Caspian Sea and countries of the Middle East and North-East Africa to India.

The colonies of slaty-backed gull (Larus schistisagus) and vegetation development were studied on the barrier islands of the Ola lagoon (the Sea of Okhotsk), which coastline has underwent great changes over the last 40 years. The number of the birds increased 2.6 times in the last 5 years, and in 2014 reached 7 thousand pairs. Five vegetation communities with prevalence of herbaceous plants were described and shown schematically.