scholarly journals COMMENTS ON THE ARTICLE AUTHORED BY M.V. MINTS AND K.A. DOKUKINA – THE BELOMORIAN ECLOGITE PROVINCE (EASTERN FENNOSCANDIAN SHIELD, RUSSIA): MESO-NEOARCHEAN OR LATE PALEOPROTEROZOIC?

2021 ◽  
Vol 12 (3) ◽  
pp. 652-661
Author(s):  
S. G. Skublov ◽  
A. V. Berezin ◽  
L. I. Salimgaraeva
Keyword(s):  
White Sea ◽  
Distribution Patterns ◽  
Fennoscandian Shield ◽  
Mobile Belt ◽  
Chemical Compositions ◽  
The White Sea ◽  
Tectonic Model ◽  
Precambrian Geology ◽  
Dating Methods ◽  
The One

The comments are given on the article authored by M.V. Mints and K.A. Dokukina – The Belomorian Eclogite Province (Eastern Fennoscandian Shield, Russia): Meso-Neoarchean or Late Paleoproterozoic? (Geodynamics & Tectonophysics 2020, 11 (1), 151–200). The Belomorian (White Sea) province of the Fennoscandia Shield is a key site for studying the tectonics of the early periods because numerous Precambrian eclogites have been found there. It was not anticipated, but the problem of age determinations of the eclogite metamorphism of gabbroids in the White Sea mobile belt has turned out to be extremely relevant not only for this region, but also for the Precambrian geology in general. The reason is that a number of authors determine the age of eclogites as Archean (2.7–2.8 Ga), which makes the White Sea mobile belt the only example of the Archean eclogite metamorphism in the world and, therefore, the only dated evidence in support of the plate tectonic model of the evolution of the Earth’s crust at the earliest stage of its formation. The article consistently provides a critical analysis of the arguments put forward by the supporters of the Archean age of the eclogites of the White Sea mobile belt. Special emphasis is made on the isotope geochronological and geochemical features of the composition of zircons from eclogite samples, as well as on the phase and chemical compositions and distribution patterns of mineral inclusions. Considering the age of eclogite metamorphism that led to the formation of eclogites in the White Sea mobile belt, we propose our interpretation based on a set of independent isotope geochemical dating methods, including the local U- Pb method for heterogeneous zircons with magmatic cores and eclogite rims, the Lu-Hf and Sm-Nd methods for the minerals of eclogite paragenesis (garnet and omphacite). And this age interpretation is fundamentally different from the one described in the commented article: all the three methods independently determine the eclogite metamorphism as Paleoproterozoic and yield the same age of circa 1.9 Ga. According to our data, the eclogites of the White Sea mobile belt are among the most ancient high-pressure rocks, their reliably established age of metamorphism is circa 1.9 Ga, and the age of the magmatic protolith is the range of 2.2–2.9 Ga.

scholarly journals Fahlbands of the Keret archipelago, White Sea: the composition of rocks and minerals, ore mineralization

2020 ◽  
Vol 245 ◽  
pp. 513-521
Author(s):  
Laysan Salimgaraeva ◽  
Sergey Skublov ◽  
Aleksey Berezin ◽  
Olga Galankina
Keyword(s):  
White Sea ◽  
Mobile Belt ◽  
The White Sea ◽  
Geochemical Characteristic ◽  
Ni Content ◽  
Icp Ms ◽  
Ore Mineralization ◽  
Sulfide Content ◽  
Small Grains ◽  
Host Rocks

This paper presents a complex mineralogical and geochemical characteristic (based on SEM-EDS, ICP-MS analysis) of the fahlband rocks of the Kiv-Guba-Kartesh occurrence within the White Sea mobile belt (WSMB). The term “fahlband” first appeared in the silver mines of Kongsberg in the 17th century. Now fahlbands are interlayers or lenses with sulfide impregnation, located in the host, usually metamorphic rock. The level of sulfide content in the rock  exceed the typical accessory values, but at the same time be insufficient for massive ores. Fahlbands are weathered in a different way than the host rocks, so they are easily distinguished in outcrops due to their rusty-brown color. The studied rocks are amphibolites, differing from each other in garnet content and silicification degree. Ore mineralization is represented mainly by pyrrhotite and pyrite, and pyrrhotite grains are often replaced along the periphery by iron oxides and hydroxides, followed by pyrite overgrowth. At the same time, the rock contains practically unaltered pyrrhotite grains of irregular shape with fine exsolution structures composed of pentlandite, and individual pyrite grains with an increased Ni content (up to 5.4 wt.%). A relatively common mineral is chalcopyrite, which forms small grains, often trapped by pyrrhotite. We have also found single submicron sobolevskite and hedleyite grains. The REE composition of the fahlband rocks suggests that they are related to Archean metabasalts of the Seryakskaya and Loukhsko-Pisemskaya structures of the WSMB, rather than with metagabbroids and metaultrabasites common in the study area.

scholarly journals Mercury in the water of small rivers of the Onega Bay basin of the White Sea

2019 ◽  
Vol 487 (1) ◽  
pp. 93-96
Author(s):  
Yu. A. Fedorov ◽  
A. E. Ovsepyan ◽  
V. A. Savitskiy ◽  
A. A. Zimovets ◽  
I. V. Dotsenko
Keyword(s):  
Anthropogenic Impact ◽  
White Sea ◽  
Small Rivers ◽  
The White Sea ◽  
Natural Conditions ◽  
Onega Bay ◽  
The One ◽  
Dissolved Mercury ◽  
The Relationship ◽  
Hydrological Phases

The results of the expeditionary studies of the mercury behavior in the water of small rivers of the Onega Bay basin of the White Sea are presented. Priority forms of mercury migration have been identified and the forms of its location along the trunk of the Kyanda River have been calculated. The relationship between the content of various forms of mercury on the one hand and salinity, pH, Eh waters on the other has been analyzed. The influence of hydrological phases on the transformation of inorganic forms of mercury has been revealed. Differences in the levels of content of dissolved mercury and its connection with the salinity in the extuar areas of the marginal filters of the Subarctic rivers in natural conditions and the environment of anthropogenic impact were established.

Paleoproterozoic remagnetization in the white sea mobile belt, Karelia: Petro-paleomagnetic evidence and supercomputer modeling

2015 ◽  
Vol 70 (2) ◽  
pp. 84-96 ◽  
Author(s):  
N. V. Lubnina ◽  
V. S. Zakharov ◽  
M. A. Novikova ◽  
V. P. Vorontsova
Keyword(s):  
White Sea ◽  
Mobile Belt ◽  
The White Sea

scholarly journals Mercury in White Sea bottom sediments: distribution, sources, and deposition chronology

2019 ◽  
Vol 59 (1) ◽  
pp. 153-162
Author(s):  
Yu. A. Fedorov ◽  
A. E. Ovsepyan ◽  
V. A. Savitsky ◽  
A. P. Lisitzin ◽  
V. P. Shevchenko ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
White Sea ◽  
Dry Weight ◽  
Distribution Patterns ◽  
Mercury Content ◽  
General Tendency ◽  
The White Sea ◽  
Sea Bottom ◽  
Kandalaksha Gulf ◽  
Landslide Processes

For the first time, vertical and lateral distribution patterns of mercury in White Sea bottom sediments have been determined. An abrupt change in the nature of mercury concentrations has been revealed, with a general tendency to decrease with depth. Natural variations in mercury concentrations within 0.01 - 0.03 μg/g dry weight (dw) have been established. An upper value of 0.03 μg/g dw is taken for the natural background content of the element. The distribution of mercury concentrations in the sequence of bottom sediments is influenced by both anthropogenic and natural factors and processes. With distance from the marine -estuary boundary of the Northern Dvina River, the river’s role in supplying mercury to the White Sea is reduced, and global and regional atmospheric mass transfer take over. The mercury content is used as an indicator of landslide processes in Kandalaksha Gulf of the White Sea. The accumulation chronology of mercury in White Sea sediments is studied, and the proportion of anthropogenic mercury is calculated.

Archean rock homologs in the Kola superdeep borehole section in the northern part of the White Sea mobile belt, Voche-Lambina test site

2012 ◽  
Vol 442 (1) ◽  
pp. 28-31 ◽  
Author(s):  
L. N. Morozova ◽  
F. P. Mitrofanov ◽  
T. B. Bayanova ◽  
V. R. Vetrin ◽  
P. A. Serov
Keyword(s):  
White Sea ◽  
Test Site ◽  
Mobile Belt ◽  
The White Sea ◽  
Archean Rock ◽  
Superdeep Borehole ◽  
Kola Superdeep Borehole

New petro-paleomagnetic data of Kandalaksha and Onega Bay Islands in the White Sea

2020 ◽  
Author(s):  
Natalia Kosevich ◽  
Ivan Lebedev ◽  
Tanya Bagdasaryan
Keyword(s):  
Magnetic Susceptibility ◽  
White Sea ◽  
Flow Direction ◽  
Mobile Belt ◽  
Magnetic Fraction ◽  
The White Sea ◽  
Petrographic Composition ◽  
North West ◽  
Kandalaksha Bay ◽  
Onega Bay

<p>We have studied the AMS of metamorphic rocks (gneiss, granitoids, dykes) and soft sediments (mainly marine sediments or reworked diamicton) from the Kandalaksha and Onega Bay’s Islands of the White sea. The objects of research are located within the White sea mobile belt, represented by large tectonic nappes.</p><p>The magnetic susceptibility in soft sediment samples ranges from 78.6 E-6 to 1525E-6 (Km), and the degree (P) from 1.8% to 4.1%. Ellipsoids have a predominantly flattened type, such a distribution of AMS is typical for sedimentary rocks. At the same time, in a number of samples (from the Islands of Joker, Ipanchinikha and Olenevsky), the maximum axis is directed in a North-Westerly direction, which may indicate the flow direction. This is especially evident in flattened-triaxial ellipsoids (T=0.2-0.3). Values that have a T greater than 0.5 have a predominantly northerly direction and the orientation of minerals of the magnetic fraction and the direction of paleoflow is less pronounced.</p><p>The study of the anisotropy of the magnetic susceptibility of the Archean complexes composing the Islands of the Kandalaksha Bay of the White sea showed a high magnetic susceptibility-5E-6-1E-3 (Km), which confirms the change in the petrographic composition of gneiss. The degree of anisotropy (P) is 9% on average. It was found that the distribution of the main axes of the magnetic susceptibility ellipsoid coincides with shale and banding in the root outlets, while the maximum axis of the ellipsoid coincides with the West-North-West stretch of the regional fault. In the Onega Bay we sampled paleoproerozoic dykes, and there are AMS is coincided as contacts of studied dykes.</p><p>We done alternating field and thermal demagnetization of pilot collection which contains samples from all studied complexes. And it gives us not good results because of bad paleomagnetic record. Most of samples contain only low coercive or low temperature components and it mainly has modern direction.</p>

scholarly journals 134Cs, 137Cs, 40K, 232Th, 226Ra in bottom sediments of the Dvina Bay on the White Sea (the Suhoe Sea Gulf)

2018 ◽  
Vol 18 (4) ◽  
pp. 148-154 ◽  
Author(s):  
Vidas Kriauciunas ◽  
Stanislav Iglovsky ◽  
Alexander Bazhenov ◽  
Irina Kuznetsova ◽  
Evgenya Shakhova ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
White Sea ◽  
Sea Water ◽  
Specific Activity ◽  
Chemical Properties ◽  
Statistical Processing ◽  
Distribution Patterns ◽  
Nuclear Industry ◽  
The White Sea ◽  
Natural Processes

The Suhoe Sea Gulf is a unique White Sea water body. Taking into account the risk of contamination of the White Sea with radionuclides as a result of the activities of the domestic and foreign nuclear industry and considering the plans to construct a deep-water part of the Arkhangelsk port on the Kuya River, the content and distribution patterns of natural and man-made radionuclides in the bottom sediments of the Suhoe Sea Gulf need to be studied. The specific activity of radionuclides was measured using a PROGRESS-2000 gamma spectrometer. Statistical processing of the data was performed using the STATISTICA (data analysis software system), version 10 software by StatSoft, Inc. (2011). The average specific activity of 226Ra, 232Th and 40K was 6.5 ± 1.4, 14.2 ± 4.3, 416 ± 89, accordingly. 134Cs and 137Cs were detected in 4 and 5 samples with a mean specific activity value of 3.3 ± 1.6 and 3.5 ± 1.1, respectively. The highest specific activity values of 40K are confined to the pelitic deposits. The main driving force in the processes of accumulation and redistribution of 232Th is gravitational water accumulation and mechanical transfer. The measured values of the specific activity of radionuclides do not exceed those previously determined by other authors in the bottom sediments of the White Sea. Correlation analysis showed a significant relationship between the content of 134Cs and 137Cs (0.77, p = 0.05), 232Th and 40K (0.67, p = 0.05) and 137Cs and 40K (0.84, p = 0.05). Factor analysis allowed two groups of radionuclides to be identified, their content being is determined by different processes: 134Cs, 137Cs, and 40K are jointly controlled by the most powerful factor (50%) and 232Th is affected by the weaker factor (29 %). Both factors are based on natural processes of radionuclide receipt and redistribution: the first factor reflects the ability of bottom sediments to adsorb 40K and isotopes of cesium, which are similar in chemical properties, and the second one reflects the natural process of removal by rivers of 232Th with terrigenous material.

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