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781.
Lein A. Yu. Rusanov I. I. Zakharova E. E. Flint M. V. Ivanov M. V. 《Doklady Earth Sciences》2010,432(1):687-689
Within the mass of recent (unit-I) and ancient Black Sea (unit-II) sediments on the outer shelf of the Russian sector of the
Black Sea, the rates of anoxic processes participating in diagenetic transformations of carbon and sulfur compounds were first
measured using 35S and 14C radioactive tracers. The main energy source for biogeochemical processes in (unit-I) sediments is the organic matter (OM)
supplied to the bottom from the water mass. In (unit-II) sediments, this is methane in a migratory form proved by the excess
of its oxidation rate over that of its generation. In recent silt, the primary microbial process is sulfate reduction; in
unit-II, this is methane anoxic oxidation by the consortium of archeides and sulfate reductants. The organic matter produced
in methane oxidation, in turn, acts as an energy source for the community of anaerobic heterotrophic microorganisms in the
bottom sediments, which are remote from the water-sediment interface. 相似文献
782.
783.
P.E. Mikhailik A.I. Khanchuk E.V. Mikhailik M.V. Ivanov V.A. Rashidov N.V. Zarubina M.G. Blokhin N.N. Barinov S.P. Pletnev 《Russian Geology and Geophysics》2018,59(3):217-225
Variations in mercury contents in marine sediments have implications for hydrothermal activity, paleoclimate, depositional environments, and primary bioproduction. Mercury contents reach 148 ppb in hydrogenic ferromanganese crusts on flat-topped seamounts. Such crusts, with up to 4120 ppb Hg, were dredged from the slopes of Seth Guyot in the western Marcus-Wake Seamounts in 1982, during the 13th cruise of RV Vulkanolog. The Seth Fe-Mn crusts are of the same origin as hydrogenic Co-rich ferromanganese deposits from seamounts in other oceanic regions. Mercury accumulated in the Cenozoic as Fe-Mn oxyhydroxides in the crusts adsorbed Hg from bottom water. The process was especially rapid during the Pliocene volcano-tectonic rejuvenated stage. 相似文献
784.
On the basis of the intrinsic (U – B)0 colours of the cepheid variables, found by the authors, the UV-excesses in the maximum and minimum light δ(U – B)max and δ(U – B)min are defined. It is found out that the UV-excesses in the maximum light δ(U – B)min increase with the period P (Fig. 2), but there is no correlation between δ(U – B)min and log P. A correlation between δ(U – B)max and the “amplitude defects” fB is also determined. These results in connection with some other considerations, as well as the possible causes of the UV-excesses, are discussed. 相似文献
785.
Summary Northern Hemisphere monthly mean temperature anomalies during the twentieth century exhibit seasonal differences. To expose
the most significant intermonthly dissimilarities, here we investigate this issue in more details. We show that the trends
significantly differ for the months close to the equinoxes. Using the technique of multidimensional scaling analysis we find
that two underlying attributes are sufficient to acceptably describe the structure of the observed intermonthly dissimilarities.
Namely, these are the monthly sample percentiles around the 30th and the 70th together with the linear trends. We find that
intraannual temperature anomaly dissimilarities statistically depend on the seasonal cycles of the Northern Hemisphere oceanic
heat content, sea ice and snow cover and the Arctic sea ice cover as well as on the seasonality of the chaoticity of the Northern
Hemisphere atmospheric dynamics. We also speculate that the annual cycles of these ocean and cryosphere characteristics statistically
set the pattern for the observed course of linear warming over the calendar months. 相似文献
786.
Yu. V. Erokhin V. A. Koroteev V. V. Khiller E. V. Burlakov K. S. Ivanov D. A. Kleimenov 《Doklady Earth Sciences》2017,477(2):1441-1444
New data on the mineral composition of Kargapole meteorite, which was found in Kurgan oblast in 1961, are presented. It has been established that the meteoritic material is represented by olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (diopside), plagioclase (oligoclase), chromite, Fe and Ni metal particles (kamacite, taenite, tetrataenite), sulfides (troilite, pentlandite), chlorapatite, and merrillite. For the first time, diopside, tetrataenite, pentlandite, chlorapatite, and merrillite were identified in the Kargapole meteorite. The chemical compositions of all minerals studied are given in Table 1. In terms of petrology, the meteorite is classified a common H4 chondrite. 相似文献
787.
The Klyuveskoi gabbro-ultramafic massif is the most representative ophiolite complex on the eastern portion of the Uralian
paleoisland arc part. The massif is composed of dunite-harzburgite (tectonized mantle peridotites) and dunite-wehrlite-clinopyroxenite-gabbro
(layered part of the ophiolite section) rock associations. The U-Pb age was obtained for the accessory zircons from the latter
association using a SHRIMP-II ion microprobe at the Center for Isotopic Research at the Karpinskii Russian Geological Research
Institute. The euhedral zircon crystals with thin rhythmic zoning from dunites are 441.4 ± 5.0 Ma in age. Zircons from olivine
clinopyroxenite show three age clusters with sharply prevalent grains 449.0 ± 6.8 Ma in age. Two points give 1.7 Ga, which
is probably related to the age of the mantle generating the layered complex. One value corresponds to 280 Ma, which possibly
reflects exhumation of ultramafic rocks in the upper crust during the collision of the Uralian foldbelt. Thus, dunites and
olivine pyroxenites from the Klyuchevskoi massif are similar in age at 441–449 Ma. The bottom of the layered part of the ophiolite
section corresponds to the M paleoboundary and, consequently, the age of the Mohorovicic discontinuity conforms with the Ordovician-Silurian
boundary in this part of the Urals. 相似文献
788.
Doklady Earth Sciences - It is shown that the observed latitudinal zonality of the Ural Fold Belt is determined mainly by the different levels of erosion of different areas. Thus, the deep levels... 相似文献