Structure and Composition of the Holocene–Pleistocene Sediments in the Northern Barents Sea

Lithology and Mineral Resources - Signs of extensive migration of gas-bearing fluids from the sedimentary cover into the water column were identified in the northern Barents Sea during Cruises 25...     

Structural–Tectonic Features of the Northeastern Barents Plate from Numerical Modeling of Potential Fields

Structural–geological inhomogeneities in the northeastern Barents Sea are zoned based on an analysis of various components of the gravity and magnetic fields. The objects revealed in the basement and sedimentary cover of the Barents Sea Plate form anomalies in potential fields at coexisting complex geological structures and contrasting petrophysical properties. Cluster analysis reveals the fault-marked boundaries of individual blocks in the basement. A numerical model of faults in the sedimentary cover and basement of the Barents Sea Plate is constructed.     

Lower–Middle Jurassic foraminiferal and ostracode biostratigraphy of the Barents Sea shelf

The Barents Sea shelf is an attractive target as a prospective large petroleum province. Further development of geological and geophysical exploration in the area requires high-resolution biostratigraphic constraints and update stratigraphic charts. The zonal succession of Lower and Middle Jurassic assemblages of foraminifers and ostracodes of the Barents Sea fits well the division for northern Siberia based on correlated independent Jurassic and Cretaceous zonal scales on all main microfossil groups, of which some scales were suggested as the Boreal Zonal Standard. The stratigraphic range of the Barents Sea microfossil assemblages has been updated through correlation with their counterparts from northern Siberia constrained by ammonite and bivalve data. Joint analysis of foraminiferal and ostracode biostratigraphy and lithostratigraphy of the sections allowed a revision to the stratigraphic position and extent of lithological and seismic units. The discovered similarity in the Lower and Middle Jurassic lithostratigraphy in the sections of the Barents Sea shelf and northern Siberia, along with their almost identical microfossil taxonomy, prompts similarity in the Early and Middle Jurassic deposition and geological histories of the two areas.     

Structure of the Earth’s crust in the northern part of the Barents–Kara region along the 4-AR DSS profile

The 1370 km long 4-AR reference profile crosses the North Barents Basin, the northern end of the Novaya Zemlya Rise, and the North Kara Basin. Integrated geophysical studies including common deep point (CDP) survey and deep seismic sounding (DSS) were carried out along the profiles. The DSS was performed using autonomous bottom seismic stations (ABSS) spaced 10–20 km apart and a powerful air gun producing seismic signals with a step size of 250 m. As a result, detailed P- and S-wave velocity structures of the crust and upper mantle were studied. The basic method was ray-tracing modeling. The Earth’s crust along the entire profile is typically continental with compressional wave velocities of 5.8–7.2 km/s in the consolidated part. Crustal thickness increases from 30 km near the islands of Franz Josef Land to 35 km beneath the North Barents Basin, 50 km beneath the Novaya Zemlya Rise, and 40 km beneath the North Kara Basin. The North Barents Basin 15 km deep is characterized by unusually low velocities in the consolidated crust: The upper crust layer with velocities of 5.8–6.4 km/s has a thickness of about 15 km beneath the basin (usually, this layer wedges beneath deep sedimentary basins). Another special property of the crust in the North Barents Basin is the destroyed structure of the Moho.     

Main Sources of 134Cs in the Barents and Kara Seas (1960–2020)

Doklady Earth Sciences - The role of the short-lived 134Cs radionuclide in the formation of the radioecological background in the marine environment of the Arctic is studied. This paper analyzes...     

Geodynamics of the Barents–Kara margin in the Mesozoic inferred from paleomagnetic data on rocks from the Franz Josef Land Archipelago

New data on paleomagnetism and isotope geochronology of Jurassic and Early Cretaceous basic igneous rocks on Franz Josef Land Archipelago (FJL) represented by flows and dikes are discussed. The first paleomagnetic data obtained for these rocks offer the opportunity to suggest a model of spatial changes in the FJL block position during the Jurassic?Cretaceous. In the Early Jurassic, the block occupied a different position relative to Europe from the modern one. It was displaced in the northeasterly direction by a distance of approximately 500 km and rotated clockwise by about 40° relative to its modern position. By the Early Cretaceous, the FJL block occupied a position close to the present-day one avoiding subsequent substantial relative displacements. The data obtained are of principal significance for reconstructing the geodynamic evolution of Arctic structures in the Mesozoic and contribute greatly to the base of paleomagnetic data for the Arctic region, development of which is now in progress.     

Barents Sea hydrodynamics change during the El Niño event

On the basis of model calculations, mutually fitted fields were obtained for the key hydrophysical properties in the vicinity of the hydrological sections executed in the Barents Sea during 1997–1998. Integrated analysis of these data allowed us to evaluate the variability of crucial hydrodynamic conditions: the decrease of supply of relatively warm and saline North Atlantic waters with compensatory inflow of Arctic waters; the decrease of total heat content and increase of thermal convection; the weakening of water dynamics in the system of general cyclone circulation; and the abnormally cold winter in 1997–1998 with the increase in the ice covering of the Barents Sea. With a high confidence probability, it was found that considerable deviations from the mean weather conditions took place in response to the El Niño global disturbance of the same period, with the maximum southern oscillation index (SOI) in January–March 1998. The El Niño signal in the baric field of the Arctic basin, noted even in November–December 1997 as a crest of increased pressure, reached its maximum development in April–June 1998 in the form of a well-pronounced atmospheric anticyclone. Recognizing the natural correlation of this phenomenon and the maximum SOI value, one may state that the Barents Sea responds to an El Niño event in about three months. This circumstance should be used as an important parameter for climate forecasting.     

Strontium-90 in Seawater and Bottom Sediments of the Barents Sea Shelf (2000–2019)

Doklady Earth Sciences - The long-term dynamics of the 90Sr concentration in water and bottom sediments of the Barents Sea is analyzed. The dependence of the distribution of 90Sr on the conditions...     

Large-Scale Atmospheric–Oceanic Interaction Regimes in the Norwegian and Barents Seas

Doklady Earth Sciences - Large-scale atmosphere–ocean interaction in the Atlantic sector of the Arctic Ocean is analyzed. New studies demonstrate that the variability of Atlantic water inflow...     

First Determination of the Isotope Age of the Andesite–Dacite Complex of the Eastern Zone of the Middle Urals

Doklady Earth Sciences - This paper reports on the first U–Pb dating of zircons from dacites of the volcanic paleo-edifice of the andesite–dacite complex of the Eastern Zone of the...     

Analysis of the degree of contamination and evolution in the last 100 years of the composition of the bed sediments of the Anllóns Basin

In this study, five cores of the Anllóns River bed sediments were analyzed in order to evaluate the downcore and downstream variations in their chemical composition. The first step was the evaluation of the metal distribution in the bulk (<2 mm) and fine fractions (<63 μm). The analysis revealed that most of the metals followed the same trend in both fractions, although the fine fraction presented usually higher concentrations. However, the concentration of both fractions tended to equalize with increasing contamination. No general increase was observed in the metal concentrations toward the surface which could be attributed to recent anthropogenic contributions. Instead, the distributions were homogeneous or peaked at various depths downcore. The most important historical feature was observed at the mouth of the river, at 96-cm depth, corresponding to the end of the eighteenth century. Upcore increased metal concentrations in parallel with increased fine fraction occurred from this depth, which were attributed to a bridge construction and consequent changes in sediment dynamics. As the metal concentrations can be influenced by variations in texture or other sediment characteristics, the second step was to evaluate the efficiency of several normalized indexes in the assessment of the degree of contamination, by calculating the enrichment factor (EF), the geoaccumulation index (I _GEO) and the pollution load index (PLI). The EFs obtained were <10, thus revealing little anthropogenic inputs to the basin. The I _GEO produced higher values when compared with the EFs. Instead of absolute EF or I _GEO absolute values, the use of cumulative probability plots allowed identifying more accurately potential outliers indicating contamination. Only one population was identified for Zn and Pb, with a reduced number of outliers at the highest concentrations for Pb. As shown, a more complex plot with the outliers identified at C4 and C5. Finally, the PLI allowed determining the absence of a significant contamination in the bed sediments. The bioavailable and non-geogenic fractions contribute up to a 90% of the total concentrations in the case of As and Cu, and showed similar (dissimilar) profiles in comparison with total metals. Also, the quality guidelines were surpassed, so the high solubility of As, Zn, Pb and Ni in the sediments revealed the need to monitor the bed sediment quality of the Anllóns River.     

Present-day tectonics of the western part of the Dzhugdzhur–Stanovoi Terrane of the southeastern frame of the North Asian Craton

The first results on current movements are presented for the western part of the Dzhugdzhur–Stanovoi Terrane based on GPS geodesy of a geodynamic survey area of the Upper Amur region. Processing of the GPS data resulted in a vector field of the displacement rates of points of the geodynamic survey area with zones of intense deformations. It was concluded from a comprehensive analysis of geological–geophysical data and estimates of the displacement rates that the terrane is characterized by kinematic integrity and was subjected to a complex of tectonic factors related to the evolution of the eastern segment of Baikal Rift Zone in the area of transpression interaction of the Eurasian and Amur plates.     

Bursting the limits of time： the reconstruction of geohistory in the age of revolution

Bursting the Limits of Time by the distin- guished historian of geology Martin Rudwick is a massive, two-part book. The first part contains what he calls a synchronous history of what eventually became historical geology in western Europe between the time of de Sans- sure＇s epoch-making ascent of Mont Blanc in 1787 and the discovery of the Kirkdale hyaena cave by Buckland in the winter of 1821-1822,     

Features of the Influence of Weather Conditions on the Deformation Processes of the Upper Layer of the Earth’s Crust

Doklady Earth Sciences - The influence of the temperature and moisture content of the near-surface soil layer on variations of the barodeformation interaction of the boundary layer of the...     

Numerical Modeling of the Effects of Major Elements on the Solubility of Chrome–Spinel and a Likely Solution of the Problem of the Origin of Chromitite

Doklady Earth Sciences - The influence of variations in fo-, fa-, en-, fs-, di-, an-, and ab-components in a high-Mg basaltic melt on the topology of the spinellide liquidus was analyzed using the...     

On the Origin of the Carat as the Unit of Weight for Gemstones

The carat is the unit of weight for diamonds and other gemstones.It corresponds to the average weight of the seeds of a leguminous tree.What kind of tree is this?We have studied the samples from Ethiopia,Egypt,Cyprus and the United States.The tree is neither“Kuara“nor“Locust“（Robina pseudoacacia Linn.）,but rather Carob(Ceratonia Siliqua).In Ethiopia,as called by local inhabitants,“Kuara“is a species of Erythrina-E.brucei rather than E.abyssinica.As might be expected,using the seeds as a means of weighing an extremely valuable commodity is not very scientific.Before 1907,at various times and in various countries,there were at least twenty-three stan-dards for the carat ranging from 187.00mg to 215.990mg.The metric carat equal to 200mg was proposed in Paris in 1907.It was adopted in the United States on July1,1913 and now is the world-accepted standard.But in reality,the standard of the carat is still confused with respect to its usage throughout the world .This is why the author reiterates that the standard of the car-at should be integrated with the metric system.     

Estimation of the stress state of the Earth’s crust and the upper mantle in the area of the Southern Kuril Islands

The catastrophic Shikotan earthquake of October 4 (5), 1994, occurred in the Pacific Ocean. Its focus was located 80 km eastward of Shikotan Island. The stress state of the Earth’s crust in this area was estimated by the method of the cataclastic analysis of the whole range of the earthquake mechanisms. The performed reconstruction of the parameters of the current stress state of the Earth’s crust and the upper mantle in the area of the Southern Kuril Islands made it possible to establish that this area is characterized, on the one hand, by the presence of extensive areas of steady behavior of the stress tensor parameters and, on the other hand, by the presence of local sections of anomalously fast changes in these parameters.     

The Nature of the “Voice of the Sea”

Strong vibrations of the Earth’s crust in the frequency range of 7–9 Hz, referred to as the “voice of the sea,” have been recorded in the course of processing synchronous experimental data obtained during recording of variations in the deformation of the Earth’s crust using a shore laser strainmeter, atmosphere pressure variations using a laser nanobarograph, and hydrosphere pressure variations using a laser meter for hydrospheric pressure and wind velocity variations. The nature of these vibrations and their transformation to adjacent geospheres have been discussed.