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Ryabchuk D.,VSEGEI | Vallius H.,GTK | Zhamoida V.,VSEGEI | Kotilainen A.T.,GTK | And 4 more authors.
Baltica | Year: 2017

Neva Bay is the shallowest and easternmost part of the Gulf of Finland (Baltic Sea). St. Petersburg, Russia’s second largest city, occupies the coastal area where the Neva River debouches into Neva Bay. St. Petersburg has a protracted history of industrial, transportation and urban related activity that have affected Neva Bay. By the sealing off the bay from the eastern Gulf of Finland, the St. Petersburg Flood Protective Facility, which was constructed from the 1970‘s to 2011, transformed Neva Bay into a “technogenic” lagoon. Neva Bay sediments record a unique history of pollution near the metropolis. Heavy metal concentrations of most elements studied varied consistently throughout sediment cores. Temporal trends indicate that metals started to accumulate abruptly in the first half of the 20th century. Zinc, lead and copper were the first metals to reach contaminant thresholds implicating the regional base metal industry as a source. Significant increase in cadmium levels a decade or two later suggests pollution from the regional chemical industry. Comparison of geochemical data collected from sediment cores and recent annual sediment surveys highlighted the temporal history and potential sources of pollution in Neva Bay. Intensive dredging in 2007–2008 resuspended and redistributed contaminated sediment around Neva Bay causing a dramatic increase in benthic sediment heavy metal concentrations. Concentrations of all measured metals subsequently declined from 2009–2014 relative to the elevated values observed for 2007–2008. Pollution history of Neva Bay bottom sediments is closely linked with changing of sedimentation conditions. Analyses of sedimentological data collected by 20th and 21st century scientific surveys reveal dramatic shifts in Neva Bay sedimentation processes over the last three centuries. The western part of Neva Bay has transitioned from a sand dominated system to one of mud accumulation with the aerial extent of mud deposition expanding significantly during the 20th century. This inventory coupled with an understanding of primary natural and anthropogenic processes can help inform decision makers to support the overall ecological health of the bay. © Baltica 2017.

Breitkreuz C.,TU Bergakademie Freiberg | Eliwa H.,Menoufia University | Khalaf I.,Menoufia University | Gameel K.E.,TU Bergakademie Freiberg | And 5 more authors.
Precambrian Research | Year: 2010

Chronology of Neoproterozoic volcanosedimentary successions remains controversial for many regions of the Arabian-Nubian Shield, including the Dokhan Volcanics of NE Egypt. New U-Pb zircon SHRIMP ages have been obtained for 10 silica-rich ignimbrites and two subvolcanic dacitic bodies, mapped as Dokhan Volcanics, from the North Eastern Desert of Egypt. Crystallization ages range between 592 ± 5 and 630 ± 6. Ma (Early Ediacaran). Apparently, the late consolidation of the Arabian-Nubian Shield was accompanied by the evolution of isolated volcanic centres and basin systems which developed during a period of approx. 40. Ma, independently in space and time and probably under changing tectonic regimes. The obtained age data together with other previously published reliable ages for Dokhan Volcanics suggest two main pulses of volcanic activity: 630-623. Ma and 618-592. Ma. Five samples contain inherited zircons, with ages of 669, 715-746, 847 and 1530. Ma, supporting models that North Eastern Desert crust is mainly juvenile Neoproterozoic crust. © 2010 Elsevier B.V.

Mikhalsky E.V.,VNIIOkeangeologia | Henjes-Kunst F.,Bundesanstalt fur Geowissenschaften und Rohstoffe | Belyatsky B.V.,VNIIOkeangeologia | Roland N.W.,Bundesanstalt fur Geowissenschaften und Rohstoffe | Sergeev S.A.,VSEGEI
Precambrian Research | Year: 2010

We report isotopic (Sm-Nd, Rb-Sr and zircon Hf and U-Pb SIMS SHRIMP) data on rocks collected from various localities throughout the southern Prince Charles Mountains known as the Ruker Province. The area is made up of a high-grade metamorphic basement, overlain by variably deformed and metamorphosed supracrustal associations of Proterozoic age. The area comprises two distinct tectonic terranes, experienced major tectonothermal processes in the Archaean (ca. 3400-2800. Ma: the Ruker Terrane) or in the Palaeoproterozoic (ca. 2500-2100. Ma: the Lambert Terrane). New zircon U-Pb ages of ca. 3180-3150. Ma, ca. 2800, and ca. 2500. Ma were obtained for various orthometamorphic rocks from the Ruker Terrane and ca. 2200. Ma, ca. 1740. Ma, and ca. 920. Ma for syn-tectonic granitic veins and leucosomes from the Lambert Terrane. The Sm-Nd data provide evidence for the initial separation of the continental crust of the Ruker Terrane from the mantle mainly between ca. 3.2 and 3.4. Ga, but up to 3.8. Ga, and indicate the presence of two mantle reservoirs which correspond to (1) depleted to slightly enriched, and (2) ultra-depleted mantle. Some material was also derived from the mantle at ca. 2.7-3.0. Ga; the crust of this age apparently underlies the central part of the Ruker Terrane (the Cumpston. Massif-Mt Newton block), which is also distinguished by younger (ca. 2.5-2.1. Ga) zircon ages. The Lambert Terrane contains subordinate ca. 3.6-3.8. Ga protoliths, and the bulk of the crust seems to have originated between 2.6-2.9. Ga from various mantle sources and it may represent an accretional complex onto the Archaean Ruker Terrane.We also summarize published isotopic data and propose an integrated geological evolution for both terranes of the Ruker Province, discuss its relationships with the bordering Rayner Province, and compare its isotopic features with other Precambrian cratons of Gondwana. The key geological features of the Ruker Terrane suggest a similarity to the Yilgarn Craton, which would imply considerable mineral resource potential of the Prince Charles Mountains. © 2010 Elsevier B.V.

Petrov O.V.,VSEGEI | Smelror M.,Geological Survey of Norway
Polar Record | Year: 2014

Following an initiative taken by the Russian Ministry of Natural resources and Ecology and by the Federal Agency of Mineral Resources (Rosnedra) in 2003 international cooperation on compiling a new generation of circum-Arctic geological and geophysical maps (in scale 1: 5 000 000) was undertaken by a consortium of national agencies from Canada, Denmark, Finland, Norway, Russia, Sweden and the USA. The polar stereographic maps include onshore and offshore geological coverage to 60° N. The bedrock map and database was first published in 2008, the geophysical maps were completed in 2010, while a tectonic map is currently in press. The new circum-Arctic maps are formally published under the Comission for the Geological Map of the World (CGMW/CCGM). A metallogenic map and database of the main occurrences of onshore and offshore metal deposits is scheduled to be completed in 2016. Copyright © 2014 Cambridge University Press.

Sobolev P.O.,VSEGEI | Soloviev A.V.,Russian Academy of Sciences
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

The regional Late Cretaceous-Cenozoic exhumation event is rather poor investigated for the Russian part of the Barents Sea. Recently interpretation of existing offshore well logs for the Russian Barents Sea was performed and generalized porosity-depth trends were compiled (Sobolev, 2012). The results of porosity-depth analysis were supplemented with sonic log interpretation and vitrinite reflectance data to provide assessment of the total Mesozoic-Cenozoic exhumation magnitude. In this study we extended the latter approach to interpolate the results from wells using seismic velocity data from common-depth point seismic reflection surveys. The previous point assessments of the regional Cenozoic exhumation magnitude were significantly improved. Differential exhumation throughout the province has occurred. The least uplift and erosion (400-500 m) occur in the depocenters of both South and North Barents Sea Basins. The combined fission-track and U/Pb dating of apatite by LA-ICP-MS was used for reconstruction of the thermal history. The apatite from all 13 samples (Fersmanovskaya-1 well) was dated is partially annealed. The tentative interpretation of fission-track data shows that the Lower Triassic - Lower Jurassic rocks, apparently, used to be within the partial annealing zone in Middle Jurassic - Cretaceous, and an acceleration of exhumation occurred in Early Paleogene (∼60 Ma). Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

Vasilyev M.A.,VSEGEI | Daragan-Suschova L.A.,VSEGEI | Rukavishnikova D.D.,Russian Academy of Sciences
Geomodel 2013 - 15th Scientific-Practical Conference on Oil and Gas Geological Exploration and Development | Year: 2013

The work deals with evaluation of Cenozoic uplift and associated erosion of the Eastern part of the Barents Sea sedimentary basin based on 2D multichannel seismic data results using interval velocity versus depth relationships. A large amount of seismic data, including the most modern, was used. Minimum values of uplift (100 - 1400 meters) were observed in the south of the investigated area, and the maximum (500 - 2200 meters) were observed in the northern part of the area. The results we have received well correspond with basic tectonical structures of the district and coincide with previous researches results of other authors.

Sobolev P.O.,VSEGEI | Lavrenteva M.A.,VSEGEI
7th EAGE Saint Petersburg International Conference and Exhibition: Understanding the Harmony of the Earth's Resources Through Integration of Geosciences | Year: 2016

The porosity studies results of the sedimentary rocks from the South Barents Sea Basin are discussed. The porosity was estimated by several methods including well logging analysis and core measurements. As a result of the research generalized porosity trends with depth were obtained for the upper part of the basin (about 3-4 km). Main factors affecting the porosity and permeability of siliciclastic rocks were assessed. The greatest influence on the porosity has a compaction (depth). Also, both porosity and permeability depend on the cement type and grain size. These patterns have been used to study the processes of diagenesis, estimation of uplift/erosion, basin burial and petroleum systems modeling.

Sobolev P.O.,VSEGEI
Saint Petersburg 2012 - Geosciences: Making the Most of the Earth's Resources | Year: 2012

The Cenozoic regional uplift remains very poor investigated for the Russian part of the Barents Sea. Several methods were used to estimate magnitude of the uplift and erosion for the Eastern Barents Sea. First method was related with using of generalized porosity-depth trends. Geophysical well logging data from the Russian Barens Sea (about thirty deep offshore wells) were compiled and processed. The joint interpretation of sonic, gamma-ray, resistivity, spontaneous potential logs were used to calculate porosity and shale fraction for siliciclastic rocks. Comparison of smoothed exponential porosity-depth curves from different wells reveals the rate of compaction for the different kinds of sediments (sands, silts and shales) and different level of erosion. Similar results were obtained with Magara's approach for sonic logs of shales. We used vitrinite reflectance data for the independent evaluation of the uplift and for calibration. Combining the data on wells we have determinated uplifts ranging from 300 m in the south (Pechora Sea) to 700 m in the central part of the South-Barents deep and to 2 km in the Franz-Joseph Land. The magnitude of erosion increase eastward as well. Seismic profiles and structural maps were used to trace and interpolate the estimates of uplift between wells.

Kashubin S.N.,VSEGEI | Roslov Y.V.,VSEGEI | Krupnova N.A.,VSEGEI | Sakoulina T.S.,VSEGEI
4th International Conference and Exhibition: New Discoveries through Integration of Geosciences, Saint Petersburg 2010 | Year: 2010

The long-term experience of work WARRP with bottom ocean stations (offshore Barents, Kara, Okhotsk regions) and the subsequent processing of received materials have been acquired by Sevmorgeo. The powerful waves source (120 liters) and short stations interval (250 m between sources and about 10 km between bottom stations) provide registration and tracking of refraction/reflection waves. The advantage of OBS measurement is the possibility of multi component recording. It allows picking of not only P waves but also PS waves. The revision of the data was aimed at PS-wave processing resulted in S-velocity model building. Several segments of the regional lines were chosen after four component record analyses. The key factors were: (1) geological background (2) the possibility to trace PS waves. Preprocessing and picking have been performed in order to create PS wave travel time data base. New data base has been merged with existed P wave travel time date base. S-waves velocity models down to Moho boundary along segments selected have been constructed due to kinematic modeling in framework of SeisWide software although different approached were also investigated. Geological interpretation of the S velocity models obtained is presented.

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