Dynamics of intrafault deformation waves: Results of physical simulation

Doklady Earth Sciences - Physical simulation of how a large shear zone forms in terms of an elastic-viscoplastic model of the lithosphere is conducted, and computer processing of the obtained photo...     

Amplitudes of long-period PcP and the core-mantle boundary

The amplitudes of the core reflection PcP are sensitive to the wave velocities and densities in the neighborhood of the core-mantle boundary (CMB). We study the amplitude ratio of the long-period phases PcP and P from two South American deep-focus earthquakes with favorable fault-plane solution, depth and magnitude, as recorded by WWNSS and CSN stations in North America.Comparison is made with long-period PcP/P amplitude ratios, derived from theoretical seismograms for a variety of CMB models. Models from previous studies, which were mainly derived from short-period PcP observations and which are characterized by discrete layers above the CMB, are almost all inconsistent with the long-period data. The data also discriminate against low nonzero S velocities below the CMB. Simple first-order-discontinuity models of the CMB, for instance according to the Jeffreys-Bullen earth model or according to recent models based mainly on free oscillations, explain the data reasonably well.Model improvements are attempted by varying the P-velocity gradient above the CMB. The best amplitude fit is obtained for a rather strong decrease in P velocity with depth in this zone which, however, gives no acceptable traveltime fit for PcP. The scatter in body-wave amplitudes is considerable even for long-period waves and may prevent the correct assessment of that part of the amplitude variation of a phase with distance that is due to the variation of velocities and densities with depth alone.     

Evolution and observational signature of diffused antiworld

The existence of macroscopic regions with antibaryon excess in the baryon asymmetric Universe with general baryon excess is the possible consequence of practically all models of baryosynthesis. Diffusion of matter and antimatter to the border of antimatter domains defines the minimal scale of the antimatter domains surviving to the present time. A model of diffused antiworld is considered, in which the density within the surviving antimatter domains is too low to form gravitationally bound objects. The possibility to test this model by measurements of cosmic gamma ray fluxes is discussed. The expected gamma ray flux is found to be acceptable for modern cosmic gamma ray detectors and for those planned for the near future.     

Carbonate equilibria in hydrothermal systems: First ionization of carbonic acid in NaCl media to 300°C

The ionization quotients of aqueous carbon dioxide (carbonic acid) have been precisely determined in NaCl media to 5 m and from 50° to 300°C using potentiometric apparatus previously developed at Oak Ridge National Laboratory. The pressure coefficient was also determined to 250°C in the same media. These results have been combined with selected information in the literature and modeled in two ways to arrive at the best fits and to derive the thermodynamic parameters for the ionization reaction, including the equilibrium constant, activity coefficient quotients, and pressure coefficients. The variation with temperature of the two fundamental quantities $\text{Δ}\text{V}\text{?}{}^{\mathrm{o}}$ and $\text{Δ}\text{C}\text{?}{}^{\mathrm{o}}{}_{\mathrm{p}}$ were examined along the saturation vapor pressure curve and at constant density. The results demonstrated again that for reactions with minimal electrostriction changes the magnitudes and variations of $\text{Δ}\text{C}\text{?}{}^{\mathrm{o}}{}_{\mathrm{p}}$ and $\text{Δ}\text{V}\text{?}{}^{\mathrm{o}}$ with temperature are small and, in addition, $\text{Δ}\text{C}\text{?}{}_{\mathrm{p}}$ and $\text{Δ}\text{V}\text{?}$ are approximately independent of salt concentration.The results have also been applied to an examination of the solubility of calcite as a function of pH (in a given NaCl medium) for the neutral to acidic region both for systems with fixed CO₂ pressure and systems where the calcium ion concentration equals the concentration of carbon. The pH of saturated solutions of calcite with P_CO2 of 12 bars increases from 5.1 to 5.5 between 100° and 300°C.     

Ecological-geochemical assessment of the state of the Volga source of water supply to Moscow

Long-term observational data (1992?C2009) on heavy metal (Cu, Zn, Pb, Cr, Ni, V, Mo, Co, Fe, and Mn) content of different links in the Ivankovo Reservoir ecosystem are used to consider the regularities in the distribution and behavior of heavy metals in the system anthropogenic pollution sources-reservoir and its drainage area, thus enabling the assessment of the pollution level of the Volga Source of water supply to Moscow.     

中国汽车工业──改革开放后的重整与国际化

大规模的重整和广泛的国际化是改革开放后中国汽车工业发展的两个主要特征。作者首先从企业组织结构、生产能力与品种结构、规模经济和空间分布等四个方面分析了近二十年来中国汽车工业重整的效果及所形成的行业特征;其次根据利用的外资和技术的来源以及涉及的技术形态分析了其国际化的程度及在世界汽车工业中的位置;最后总结了中国汽车工业面临的若干问题,并提出在散乱的格局和跨国公司竞争的双重压力下,中国汽车工业正处于成长的关键时期。     

Geochemical signatures of two different coastal depositional environments within the same catchment

The geochemistry of lake (Renstradträsket) and estuarine (Pieni Pernajanlahti Bay) sediment was investigated in a medium sized watershed draining to the Gulf of Finland, Baltic Sea. Catchment land-use types were compared and found similar. Sediment cores were dated using ²¹⁰Pb- and ¹³⁷Cs-chronologies and analyzed for Al, K, Cu, Zn, Fe, Mn, phosphorus fractions, TN, TC and biogenic silica (BSi). Differences between the sediment cores were studied by using linear regression analysis and principal components analysis (PCA). Despite similarities in catchment land-use and history, the sediment geochemical profiles of the sites varied significantly. Some of the differences could be related to differences in chemical sedimentation environment (lacustrine versus estuarine). TP concentration was found to be positively correlated with sediment iron content in estuarine sediment but negatively correlated with Fe in lake sediment. In the estuarine core sedimentary iron was not correlated to lithogenic potassium and aluminum but in the lake core the iron seemed to be lithogenic in origin, as suggested by the strong positive correlations (r ² = 0.95–0.96) between these three variables. Most similarities among the cores were found in Al concentrations. Estuarine nutrient profiles appeared relatively monotonous compared to the lake core. This is probably due to more vigorous mixing of the sediments that may ensure more rapid and complete consumption of the organic matter deposited on the bottom of the estuary. Therefore the lake sediment appeared to preserve the historical record of eutrophication better. Biologically less active and more particle-bound materials like the trace metals Cu and Zn seemed to retain good records of anthropogenic impact also in the estuarine core. The study highlights the need to take the sedimentation environment into account when interpreting geochemical record.     

Density and conductivity properties of Na−CO3−Cl−SO4 brine from Mono Lake, California, USA

Relationships among conductivity, temperature, total dissolved solids (TDS), and density were determined for hypersaline brine (TDS, 83 g kg⁻¹) from Mono Lake. A theoretical estimate of density based on ionic composition and calculated partial molar volumes compared well with actual measurements (difference, 390 ppm). However, an empirically derived equation of state based on temperature and conductivity provides the most accurate density estimates (residual errors, 190 ppm) and can be used with data collected with CTD profilers.