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Oceanology - The variety of information obtained during scientific research and exploration of seafloor massive sulfide (SMS) deposits include significant data on the morphology of orebodies formed... 相似文献
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G. Cherkashov V. Bel'tenev V. Ivanov L. Lazareva M. Samovarov V. Shilov 《Marine Georesources & Geotechnology》2013,31(4):308-316
Two new major hydrothermal fields have been discovered in the rift valley of the MAR at 13°N (Ashadze) and l6°38′N (Krasnov). The Ashadze field consists of a cluster of active hydrothermal sites associated with ultramafic rocks and located at the greatest depth in the ocean (4,200 m). By contrast, the Krasnov field consists of inactive sulfide mounds hosted in basalts. The Krasnov is the largest hydrothermal deposit on the MAR (17.4 Mt) so far discovered with iron sulfide as the principal mineral type. By contrast, Cu-Zn sulfides are the major minerals in the Ashadze deposits, which are also enriched in gold and several other metals. 相似文献
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The role of the Spitsbergen shear zone in determining morphology,segmentation and evolution of the Knipovich Ridge 总被引：1，自引：1，他引：1
Crane Kathleen Doss Hany Vogt Peter Sundvor Eirik Cherkashov Georgy Poroshina Irina Joseph Devorah 《Marine Geophysical Researches》2001,22(3):153-205
In 1989–1990 the SeaMARC II side-looking sonar and swath bathymetric system imaged more than 80 000 km2 of the seafloor in the Norwegian-Greenland Sea and southern Arctic Ocean. One of our main goals was to investigate the morphotectonic
evolution of the ultra-slow spreading Knipovich Ridge from its oblique (115° ) intersection with the Mohns Ridge in the south
to its boundary with the Molloy Transform Fault in the north, and to determine whether or not the ancient Spitsbergen Shear
Zone continued to play any involvement in the rise axis evolution and segmentation.
Structural evidence for ongoing northward rift propagation of the Mohns Ridge into the ancient Spitsbergen Shear Zone (forming
the Knipovich Ridge in the process) includes ancient deactivated and migrated transforms, subtle V-shaped-oriented flank faults
which have their apex at the present day Molloy Transform, and rift related faults that extend north of the present Molloy
Transform Fault. The Knipovich Ridge is segmented into distinct elongate basins; the bathymetric inverse of the very-slow
spreading Reykjanes Ridge to the south. Three major fault directions are detected: the N-S oriented rift walls, the highly
oblique en-echelon faults, which reside in the rift valley, and the structures, defining the orientation of many of the axial
highs, which are oblique to both the rift walls and the faults in the axial rift valley.
The segmentation of this slow spreading center is dominated by quasi stationary, focused magma centers creating (axial highs)
located between long oblique rift basins. Present day segment discontinuities on the Knipovich Ridge are aligned along highly
oblique, probably strike-slip faults, which could have been created in response to rotating shear couples within zones of
transtension across the multiple faults of the Spitsbergen Shear Zone. Fault interaction between major strike slip shears
may have lead to the formation of en-echelon pull apart basins. The curved stress trajectories create arcuate faults and subsiding
elongate basins while focusing most of the volcanism through the boundary faults. As a result, the Knipovich Ridge is characterized
by Underlapping magma centers, with long oblique rifts.
This style of basin-dominated segmentation probably evolved in a simple shear detachment fault environment which led to the
extreme morphotectonic and geophysical asymmetries across the rise axis. The influence of the Spitsbergen Shear Zone on the
evolution of the Knipovich Ridge is the primary reason that the segment discontinuities are predominantly volcanic.
Fault orientation data suggest that different extension directions along the Knipovich Ridge and Mohns Ridge (280° vs. 330°,
respectively) cause the crust on the western side of the intersection of these two ridges to buckle and uplift via compression
as is evidenced by the uplifted western wall province and the large 60 mGal free air gravity anomalies in this area.
In addition, the structural data suggest that the northwards propagation of the spreading center is ongoing and that a `normal'
pure shear spreading regime has not evolved along this ridge.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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The results of permafrost and coastal dynamics investigations at four key sites on the shores of the Kara and Barents Seas are discussed. Three ACD key sites, Marre-Sale, Shpindler, and Kolguev, characterize areas with active thermal erosion; key site Cape Bolvansky is found on a relatively stable coast. It is found that the coastal retreat rate has spatial and temporal variability, which is typical of the entire Arctic coast. Coastal deposits on the Kara and Barents Seas have a low organic carbon content. Annual input of material into the Kara Sea resulting from coastal degradation reaches 35–40 million t, including about 7.5 million t of ice, 0.35 million t of organic carbon, and 0.3 million t of soluble salts.This revised version was published online January 2005 with corrections to the title of the article. 相似文献
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Hugues Lantuit Pier Paul Overduin Nicole Couture Sebastian Wetterich Felix Aré David Atkinson Jerry Brown Georgy Cherkashov Dmitry Drozdov Donald Lawrence Forbes Allison Graves-Gaylord Mikhail Grigoriev Hans-Wolfgang Hubberten James Jordan Torre Jorgenson Rune Strand ?deg?rd Stanislav Ogorodov Wayne H. Pollard Volker Rachold Sergey Sedenko Steve Solomon Frits Steenhuisen Irina Streletskaya Alexander Vasiliev 《Estuaries and Coasts》2012,35(2):383-400
Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447?km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5?m? year?1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales. 相似文献
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Oceanology - Sea level changes during of Earth’s glacial periods the reduce hydrostatic pressure on the ocean bottom. The decrease in hydrostatic pressure increases magmatic activity and, as... 相似文献
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V. Yu. Kuznetsov E. V. Tabuns K. A. Kuksa G. A. Cherkashov V. E. Bel’tenev Kh. A. Arslanov F. E. Maksimov L. I. Lazareva A. I. Zhuravleva A. Yu. Petrov V. A. Grigoriev 《Doklady Earth Sciences》2018,480(2):700-704
This paper reports on the integrated geochronological and geochemical methods used in studying the ore deposits and metalliferous sediments of the Yubileinoye field. This study gives the opportunity to carry out cross dating of hydrothermal deposits, including the 230Th/U dating of sulfides, the 230Th, 14C dating, and foraminiferal analysis of the sediments, and, on this basis, to reconstruct hydrothermal activity over time. It was established that the ores started forming about 100 000–123 000 years ago and were renewed 4–5 times with a frequency of 10–20 ka. As a result, the complex of pyrite-marcasite, chalcopyrite and sphalerite ores and the associated metal-bearing and ore-bearing sediments with consistent geochemical specialization were formed. The integrated geochronological and geochemical studies of the ores and sediments allow us to obtain detailed data on evolution of the hydrothermal ore-formation not only in the certain areas but also for the entire Mid-Atlantic Ridge. 相似文献
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