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1.
The characteristic pattern of multiple colored layers in coastal stratified lakes in the process of separation from the White Sea 总被引：1，自引：1，他引：0
Krasnova Elena D. Matorin Dmitry N. Belevich Tatiana A. Efimova Ludmila E. Kharcheva Anastasiia V. Kokryatskaya Natalia M. Losyuk Galina N. Todorenko Daria A. Voronov Dmitry A. Patsaeva Svetlana V. 《中国海洋湖沼学报》2018,36(6):1962-1977
An unusual feature of the saline stratified lakes that were formed due to ongoing postglacial uplift on the White Sea coast is the presence of several differently colored thin layers in the zone with sharp gradients. Colored layers in five lakes at various stages of separation from the sea were investigated using optical microscopy, spectrophotometry, spectrofluorimetry, and photobiology. The upper greenish colored layer located in the aerobic strata of all lakes near the compensation depth of 1% light penetration contains green algae. In the chemocline, another layer, brightly green, red or pink, is dominated by mixotrophic flagellates. Despite the very low light intensities and the presence of H 2 S, active photosynthesis by these algae appears to be occurring, as indicated by high values of the maximum quantum yield of primary photochemistry, electron transport activity, photosynthetic activity of photosystem II, the fraction of active centers, and low values of heat dissipation. In the reduced zone of the chemocline, a dense green or brown suspension of anoxygenic phototrophs(green sulfur bacteria) is located. 相似文献
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3.
I. F. Gertner V. V. Vrublevskii O. M. Glazunov P. A. Tishin T. S. Krasnova D. N. Voitenko 《Doklady Earth Sciences》2009,429(2):1526-1532
The REE distribution patterns and Nd whole-rock and mineral isotope ratios of the Kingash ultramafic-mafic massif enabled
us to propose a multistage history for its evolution at 1410 and 875 Ma. These stages reflect the magmatic evolution of the
Siberian paleocontinent margin during the Late Precambrian. The age of metamorphism of the massif during collision and accretion
in the Early Paleozoic (∼500 Ma) was obtained based on a Sm-Nd mineral isochron from rheomorphic veined albitite. The Nd and
Sr isotopic compositions of rocks from the Kingash massif suggest mantle sources for picritic and basic magmas, which are
thought to have originated by mixing of different proportions of depleted (PREMA or DM) and enriched (EM) melts. The initial
isotope ratios of the parental melts transformed during interaction with Sr-rich material from the host metasedimentary complexes. 相似文献
4.
S. A. Silantyev M. V. Portnyagin E. A. Krasnova F. Hauff R. Werner D. V. Kuzmin 《Geochemistry International》2014,52(3):179-196
The paper presents data on the petrology and geochemistry of plutonic rocks dredged from the Stalemate Fracture Zone, Northwest Pacific Ocean, during Cruise SO201-1 of the R/V “Sonne”. We proposed also the reconstruction of their formation conditions and interpretation of their tectonic evolution. The genesis of gabbroids found among plutonic rocks composing the Cretaceous-Paleogene basement of the northwestern part of the Pacific Ocean was related to magmatism at the ancient spreading center and provides record of the evolution of the parental magmatic melts of N-MORB. Along with related peridotites, basalts, and dolerites, these rocks can be attributed to the disintegrated the Cretaceous-Paleogene oceanic lithosphere of the Pacific Ocean. The shallow mantle beneath the ancient oceanic crust of this area is made up of depleted magmatic spinel lherzolite, harzburgite, and dunite. The fact that gabbro-diorite and diorite that are not genetically related to the rocks of the Cretaceous-Paleogene basement of the Northwest Pacific occur at the eastern termination of the Stalemate Fracture Zone possibly reflects the complicated structure of the tectonic collage of rocks of different age that were produced in different geodynamic environments and were later tectonically brought together near the frontal portion of the Aleutian island arc. Judging by the isotopic-geochemical characteristics of these rocks, they cannot be classed with the family of oceanic plagiogranites. Deformations of the oceanic basement can be discerned throughout the whole Stalemate Fracture Zone as brecciation and large-amplitude vertical displacements within the oceanic lithosphere. 相似文献
5.
Oceanology - The article presents data on the composition and abundance of algal flora in the coastal stratified Kislo-Sladkoe Lake (the Karelian coast of the White Sea) after its flushing with... 相似文献
6.
E. A. Krasnova M. V. Portnyagin S. A. Silantyev K. Hoernle R. Werner 《Geochemistry International》2013,51(9):683-695
This paper reports the results of a mineralogical study of 14 mantle peridotite samples dredged in 2009 from the eastern slope of the northwestern segment of the Stalemate Ridge in the northwestern Pacific during cruise SO201-KALMAR Leg 1b of the R/V Sonne. The sample collection included four serpentinized and silicified dunites and ten variably serpentinized lherzolites. The compositions of primary minerals (clinopyroxene, orthopyroxene, and spinel) change systematically from the lherzolites to dunites. Spinel from the lherzolites shows higher Mg# and lower Cr# values (0.65–0.68 and 0.26–0.33, respectively) compared with spinel from the dunites (Mg# = 0.56–0.64 and Cr# = 0.38–0.43). Clinopyroxene from the lherzolites is less magnesian (Mg# = 91.7–92.4) than clinopyroxene from dunite sample DR37-3 (Mg# = 93.7). Based on the obtained data, it was concluded that the lherzolites of the Stalemate Fracture Zone were derived by 10–12% near-fractional melting of a DMM-type depleted mantle reservoir beneath the Kula-Pacific spreading center. The dunites were produced by interaction of residual lherzolites with sodium- and titaniumrich melt and are probably fragments of a network of dunite channels in the shallow mantle. The moderately depleted composition of minerals clearly distinguishes the lherzolites from the strongly depleted peridotites of the East Pacific Rise and indicates the existence of slow-spreading mid-ocean ridges in the Pacific Ocean during the Cretaceous-Paleogene. 相似文献
7.
A. P. Lisitzin Yu. K. Vasil’chuk V. P. Shevchenko N. A. Budantseva E. D. Krasnova A. N. Pantyulin A. S. Filippov Ju. N. Chizhova 《Doklady Earth Sciences》2013,449(2):406-412
This study aimed to analyze the oxygen isotope composition of water, ice, and snow in water bodies isolated from the White Sea and to identify the structural peculiarities of these pools during the winter period. The studies were performed during early spring in Kandalaksha Bay of the White Sea, in Velikaya Salma Strait and in Rugoserskaya Inlet. The studied water bodies differ in their degree of isolation from the sea. In particular, Ermolinskaya Inlet has normal water exchange with the sea; the Lake on Zelenyi Cape represents the first stage of isolation; i. e., it has permanent water exchange with the sea by the tide. Kislo-Sladkoe Lake receives sea water from time to time. Trekhtsvetnoe Lake is totally isolated from the sea and is a typical meromictic lake. Finally, Nizhnee Ershovskoe Lake exhibits some features of a saline water body. The oxygen isotope profile of the water column in Trekhtsvetnoe Lake allows defining three layers; this lake may be called typically meromictic. The oxygen isotope profile of the water column in Kislo-Sladkoe Lake is even from the surface to the bottom. The variability of δ18O is minor in Lake on Zelenyi Cape. A surface layer (0–1 m) exists in Nizhnee Ershovskoe Lake, and the oxygen isotope variability is well pronounced. Deeper, where the freshwater dominates, the values of ?18Îvary insignificantly disregarding the water depth and temperature. This fresh water lake is not affected by the seawater and is not stratified according to the isotope profile. It is found that applying the values of ?18Î and profiles of temperature and salinity may appear as an effective method in defining the water sources feeding the water bodies isolated from the sea environment. 相似文献
8.
Stuart Crampin David C. Booth Maria A. Krasnova Evgenie M. Chesnokov Alexandr B. Maximov Nikolai T. Tarasov 《Geophysical Journal International》1986,84(2):401-412
Summary. Three-component seismograms of small local earthquakes recorded in the Peter the First Range of mountains near Garm, Tadzhikistan SSR, display shear-wave splitting similar to that previously observed near the North Anatolian Fault in Turkey. The Peter the First Range is in a region of compressional tectonics, whereas the North Anatolian Fault is a comparatively simple strike-slip fault. Detailed analysis of the Turkish records suggests that the splitting is diagnostic of crack-induced anisotropy caused by vertical microcracks aligned parallel to the direction of maximum compression. Preliminary examination of paper records from Garm shows that most shear waves arriving within the shear-wave window display shear-wave splitting, and that the polarizations of leading shear-waves are consistently aligned in a NE/SW direction. The area is complicated and the tectonics are not well-understood, but the NE/SW direction is approximately perpendicular to the compressional axis in many of the fault-plane mechanisms of the earthquakes. These earthquakes are usually at depths between 5 and 12 km, although there are some deeper events nearby.
Parallel shear-wave polarizations, such as those observed, are expected to indicate the strike of nearly vertical parallel microcracks, which would be aligned parallel to the direction of maximum compression. Thus the shear-wave polarizations in the Peter the First Range indicate that the directions of principal stress are reversed in the rock above the earthquake foci where thrust faulting is taking place. 相似文献
Parallel shear-wave polarizations, such as those observed, are expected to indicate the strike of nearly vertical parallel microcracks, which would be aligned parallel to the direction of maximum compression. Thus the shear-wave polarizations in the Peter the First Range indicate that the directions of principal stress are reversed in the rock above the earthquake foci where thrust faulting is taking place. 相似文献
9.
S. A. Silantyev E. A. Krasnova M. Cannat N. S. Bortnikov N. N. Kononkova V. E. Beltenev 《Geochemistry International》2011,49(4):323-354
This study aimed at reconstructing the sequence of events in the magmatic and metamorphic evolution of peridotites, gabbroids,
and trondhjemites of the oceanic core complexes of the Ashadze and Logachev hydrothermal vent fields. The study object was
the collections of plutonic rocks made during cruises 22 and 26 of the R/V Professor Logachev, Cruise 41 of the R/V Akademik Mstislav Keldysh, and the Russian-French expedition Serpentine aboard the R/V Pourquoi pas? The data reported here suggest that the oceanic core complexes of the Ashadze and Logachev fields were formed via the same
scenario in the two MAR regions. On the other hand, the analysis of petrological and geochemical characteristics of the rocks
indicated that the oceanic core complexes of the MAR axial zone between 12°58′ and 14°45′N show a pronounced petrological
and geochemical heterogeneity manifested in variations in the degree of depletion of mantle residues and the Nd isotopic compositions
of the rocks of the gabbro-peridotite association. The trondhjemites of the Ashadze hydrothermal field can be considered as
partial melting products of gabbroids under the influence of hydrothermal fluid. It was supposed that the presence of trondhjemites
in the MAR oceanic core complexes can be used as a marker for the highest temperature deep-rooted hydrothermal systems. Perhaps,
the region of the MAR axial zone in which petrologically and geochemically contrasting oceanic core complexes are spatially
superimposed served as sites for the development of large hydrothermal clusters with a considerable ore-forming potential. 相似文献
10.
Krasnova V. V. Chernetsky A. D. Panova E. M. Boltunov A. N. Litovka D. I. Svetochev V. N. Samsonov D. P. Belikov R. A. Andrianov V. V. 《Oceanology》2021,61(1):80-93
Oceanology - The OCP and PCB contents in the tissues of beluga whales (Delphinapterus leucas) from the Russian Arctic have been studied for the first time. Skin and subcutaneous adipose tissue... 相似文献