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11.
Joseph F. Whelan Leonid A. Neymark Richard J. Moscati Brian D. Marshall Edwin Roedder 《Applied Geochemistry》2008
Secondary calcite, silica and minor amounts of fluorite deposited in fractures and cavities record the chemistry, temperatures, and timing of past fluid movement in the unsaturated zone at Yucca Mountain, Nevada, the proposed site of a high-level radioactive waste repository. The distribution and geochemistry of these deposits are consistent with low-temperature precipitation from meteoric waters that infiltrated at the surface and percolated down through the unsaturated zone. However, the discovery of fluid inclusions in calcite with homogenization temperatures (Th) up to ∼80 °C was construed by some scientists as strong evidence for hydrothermal deposition. This paper reports the results of investigations to test the hypothesis of hydrothermal deposition and to determine the temperature and timing of secondary mineral deposition. Mineral precipitation temperatures in the unsaturated zone are estimated from calcite- and fluorite-hosted fluid inclusions and calcite δ18O values, and depositional timing is constrained by the 207Pb/235U ages of chalcedony or opal in the deposits. Fluid inclusion Th from 50 samples of calcite and four samples of fluorite range from ∼35 to ∼90 °C. Calcite δ18O values range from ∼0 to ∼22‰ (SMOW) but most fall between 12 and 20‰. The highest Th and the lowest δ18O values are found in the older calcite. Calcite Th and δ18O values indicate that most calcite precipitated from water with δ18O values between −13 and −7‰, similar to modern meteoric waters. 相似文献
12.
13.
We present a numerical model of the dynamics of Lake Donuzlav, which enables one to perform simultaneous numerical analyses
of the currents, sea level, waves, and sediment transport. The model is based on the hydrodynamic block and the spectral wave
model. For typical storm situations, we study the specific features of the integral circulation of waters and the three-dimensional
structure of currents, investigate the wind-induced wave fields, and evaluate the flows of sediments and deformations of the
bottom. The presence of intense eddy structures is revealed in the field of currents caused by the bottom topography. A significant
intensification of waves in the south part of the lake is established in the case of penetration of storm waves through the
strait. It is shown that the account of waves leads to qualitative changes in the structure of circulation in the lake and
to the formation of well-pronounced areas of wave-induced elevations and lowerings of the sea level.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 43–65, March–April, 2006. 相似文献
14.
V. A. Ivanov S. P. Lyubartseva N. Mikhailova N. B. Shapiro 《Physical Oceanography》2001,11(6):509-524
We analyze the results of numerical calculations performed according to the three-dimensional interdisciplinary model of an
ecological system of the Black-Sea shelf zone near the estuary of the Danube. The complete system of equations of hydrothermodynamics
is solved together with transport equations of the advection-diffusion-reaction type used to describe the transformation of
a substance (nitrogen) between the components of the characteristic vectors of the ecosystem: plankton, detritus, and biogenic
elements (nitrates). We describe the distinctive features of the circumcontinental distribution of components obtained as
a result of numerical experiments and present arguments for the conclusion that the ecosystem of the Danube estuary water
area plays the role of a buffer zone between the press of the Danubian biogenic pollutions and the neighbouring areas of the
shelf zone and open sea.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
15.
V. F. Ivanov 《Physical Oceanography》2001,11(5):425-437
On the basis of a nonlinear model taking into account viscosity, density diffusion, and currents, we perform the numerical
analysis of propagation of perturbations formed in the abyssal part of the Black Sea as a result of the action of tangential
wind stresses or density flows in the form of a strip on the sea surface. It is shown that, in the course of time, in the
region of the bottom slope, these perturbations generate a train of waves in the sea, which causes oscillations of the fields
of density and currents. There are some differences between the generation of internal waves by the flows of density and the
wind. Unlike the wind action, in the presence of flows of density in the upper layer in the region of the strip, the initial
period of generation is characterized by the formation of intense perturbations without train structure.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
16.
17.
The problem of the seasonal variations of temperature and salinity in the intermediate zone located between the West African and the Gulf of Guinea upwellings is considered. The vertical distribution of the phase-amplitude characteristics of the annual and semi-annual variations is examined in good detail and their parameters are defined from the monthly means using the least-squares fit technique. The contribution of isopycnic advection to the formation of seasonal thermohaline variations is studied.Translated by Vladimir A. Puchkin. 相似文献
18.
Ivanov V. A. Kubryakov A. I. Lyubartseva S. P. Mikhailova É. N. Shapiro N. B. 《Physical Oceanography》2004,14(2):67-83
In the present work, we generalize the results of our investigations in the field of simulation of hydrophysical and ecological processes in coastal regions of various seas and some closed basins. The developed and applied mathematical models and the results of numerical experiments are briefly analyzed. 相似文献
19.
V. F. Ivanov 《Physical Oceanography》2001,11(3):205-219
For various stratifications and different types of bottom patterns we study the transformations of solitary perturbations
of density appearing in the depth of the sea. In the two-dimensional case, under the assumption that the average dynamic characteristics
weakly vary in time as compared with the wave characteristics, we deduce the equations for mean currents and waves taking
into account vertical and horizontal viscosity and the diffusion of density. Numerical examples show that the stratification,
bottom topography, nonlinearity, mean currents, and dissipation strongly affect both the process of splitting of a solitary
wave into wave trains and their amplitude and length. The wave currents exhibit the oscillatory (train-like) character. It
is emphasized that, in the case of propagation of solitary perturbations of density with dissipation, it is also important
to take into account the combined influence of nonlinearity, currents, bottom topography, and stratification.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
20.