Mesoarchean island-arc association in the Central Karelian terrane, Fennoscandian shield: New Geochronological data     

S. A. Svetov  N. M. Kudryashov  Yu. L. Ronkin  H. Huhma  A. I. Svetova  T. N. Nazarova 《Doklady Earth Sciences》2006,406(1):103-106

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Radio and optical spectra of objects from three complete samples of radio sources     

V. L. Afanas’ev  S. N. Dodonov  A. V. Moiseev  A. G. Gorshkov  V. K. Konnikova  M. G. Mingaliev 《Astronomy Reports》2006,50(4):255-272

We present classifications, optical identifications, and radio spectra for 19 radio sources from three complete samples, with declinations 4°–6° (B1950, S _{3.9 GHz} > 200 mJy), 10°–12°30′ (J2000, S _{4.85 GHz} > 200 mJy), and 74°–75° (J2000, S _{4.85 GHz} > 100 mJy). We also present corresponding information for the radio source J0527+0331. The right ascensions are 0–24^h and the Galactic latitudes |b| > 15° for all the samples. Our observations were obtained with the 6 m telescope from the Special Astrophysical Observatory in the range 4000–9000 Å or 4000–7500 Å and the RATAN-600 radio telescope at frequencies in the range 0.97–21.7 GHz. We obtained flux densities for the radio sources and optical spectra for their optical counterparts. Nine objects were classified as quasars with redshifts from z = 1.029 to 3.212; nine objects are emission-line galaxies with redshifts from 0.172 to 0.546, and one is a galaxy with burstlike star formation at z = 0.156, and one is a BL Lac object with z = 0.509. The spectra of five radio sources were decomposed into extended and compact components. The radio source J0527+0331, identified with a BL Lac object, displays significant variations of time scales from several days to several years. Data on flux variations are presented for 11 radio sources, as well as their spectra at several epochs.  相似文献   

Ge-bearing coals of the Luzanovka Graben, Pavlovka brown coal deposit, southern Primorye     

V. V. Seredin  Yu. A. Danilcheva  L. O. Magazina  I. G. Sharova 《Lithology and Mineral Resources》2006,41(3):280-301

Results of the study of a new Ge-bearing area of the Pavlovka brown coal deposit are presented. Ge is accumulated in bed III₂ lying at the bottom of the Late Paleogene-Early Neogene coal-bearing sequence adjacent to the Middle Paleozoic granite basement. The Ge content in coals and coal-bearing rocks varies in different sections from 10 to 200–250 ppm, reaching up to 500–600 ppm in the highest-grade lower part of the bed. The metalliferous area reveals a geochemical zoning: complex Ge-Mo-W anomalies subsequently grades along the depth and strike into Mo-W and W anomalies. Orebodies, like those at many Ge-bearing coal deposits, are concentric in plan and dome-shaped in cross-section. Coals in their central parts, in addition to Ge, W, and Mo, are enriched in U, As, Be, Ag, and Au. Distribution of Ge and other trace elements in the metalliferous sequence and products of gravity separation of Ge-bearing coals is studied. These data indicate that most elements (W, Mo, U, As, Be) concentrated like Ge in the Ge-bearing bed relative to background values are restricted to the organic matter of coals. The electron microscopic study shows that Ge-bearing coals contain native metals and intermetallic compounds in association with carbonates, sulfides, and halogenides. Coal inclusions in the metalliferous and barren areas of the molasse section strongly differ in contents of Ge and associated trace elements. Ge was accumulated in the coals in the course of the interaction of ascending metalliferous solutions with organic matter of the buried peat bogs in Late Miocene. The solutions were presumably represented by N₂-bearing thermal waters (contaminated by volcanogenic CO₂) that are typical of granite terranes.  相似文献   

Occurrence of salt water above fresh water in dynamic equilibrium in a coastal groundwater flow system near De Panne, Belgium     

A. Vandenbohede  L. Lebbe 《Hydrogeology Journal》2006,14(4):462-472

A salt water lens is found above fresh water under the shore between Dunkerque (France) and Nieuwpoort (Belgium). This inverse density distribution is in a dynamic equilibrium. It develops due to the infiltration of salt water on the back shore during high tide. Under this salt water lens, water infiltrated in the adjacent dune area flows towards the sea and discharges at the seabed. This water quality distribution differs from the classic salt water wedge under fresh water described in the literature. Here, the evolution to this water quality distribution is simulated with a density dependent numerical model. A large tidal range, shore morphology and a permeable groundwater reservoir are the main conditions for the observed water quality distribution. By altering these conditions, intermediate water quality distributions between the classic salt water wedge and the one discussed here develop. Based on these simulations, it is expected that similar kinds of inverse density distribution could be present in a number of coastal areas, which have tides, a gently sloping shore and a permeable substratum.  相似文献   

The chemical composition of HR 1512, a peculiar helium-weak star     

T. M. Rachkovskaya  L. S. Lyubimkov  S. I. Rostopchin 《Astronomy Reports》2006,50(2):123-133

We have used high-resolution spectra to study the chemical composition of HR 1512, a star with effective temperature T _eff = 15 200 K, atmospheric gravity log g = 3.52, microturbulence parameter V _t = 1.5 km/s, and rotation rate v sin i = 17 km s^?1. We confirm the presence of a helium deficiency (?0.6 dex), indicating that HR 1512 is a helium-weak star. Its considerable phosphorus excess (1.6 dex) testifies that the star belongs to the PGa subtype. We suggest that the He and P abundances increase with height; i.e., that there is stratification of He and P in the star’s atmosphere. Among the CNO elements, nitrogen demonstrates an underabundance of ?0.4 dex, while the abundances of carbon and oxygen are solar. Deficits of about ?0.5 or ?0.6 dex were also found for Mg, Si, and S. A neon excess of 0.4 dex was derived from our non-LTE analysis of NeI lines. The largest excess among the iron-peak elements (Cr, Mn, Fe, and Ni) is 0.6 dex, for manganese; the abundances of chromium and nickel display excesses of 0.5 and 0.3 dex, respectively, while the iron abundance is almost normal. The chemical anomalies of HR 1512 generally agree with those for mercury-manganese stars. This supports the hypothesis that PGa stars represent an extension of HgMn stars to higher temperatures.  相似文献   

Dissolved trace elements in river water: spatial distribution and the influencing factor, a study for the Pearl River Delta Economic Zone, China   总被引：1，自引：0，他引：1  

T. P. Ouyang  Z. Y. Zhu  Y. Q. Kuang  N. S. Huang  J. J. Tan  G. Z. Guo  L. S. Gu  B. Sun 《Environmental Geology》2006,49(5):733-742

Twenty-nine water samples were collected from different river channels of the Pearl River Delta Economic Zone, China. An inductively coupled plasma-mass spectromonitor (ICP-MS) was used to measure concentrations of the trace elements in these samples. The results suggest that the average concentrations of rare earth elements in river water show an increasing trend from the West River, the North River, the rivers of the Pearl River Delta, and the Shenzhen River to the East River. Relatively high concentrations of heavy metals appear in the East River, the rivers of the Pearl River Delta and the Shenzhen River, while the West River and the North River have relatively low heavy metal concentrations. Trace element concentrations in samples collected near urban or industrial areas are much higher than those of samples collected from distant areas, away from urban and industrial areas. After natural conditions, human activities have significant influence on the trace element concentrations in river water. This trace element concentration’s spatial distribution in the river water from the Pearl River Delta Economic Zone is actually an integrated effect of natural conditions and human activity.  相似文献   

The effect of thermal treatment on the 57Fe Mössbauer spectrum of beryl     

Geraldo Magela da Costa  Gabriel de Oliveira Polli  Márcio A. Kahwage  Eddy de Grave  Antônio Claret Soares Sabioni  Júlio Cesar Mendes 《Physics and Chemistry of Minerals》2006,33(3):161-166

Mössbauer spectra (MS) of blue, green and yellow beryl (ideally Be₃Al₂Si₆O₁₈) containing approximately 1% of iron were obtained at 295 and 500 K. Room temperature (RT) spectra of both blue and green samples showed the presence of an asymmetric Fe²⁺ doublet (ΔE _Q~2.7 mm/s, δ~1.1 mm/s), with a very broad low-velocity peak. There is no clear evidence for the presence of a ferric component. The MS of the yellow sample at RT consists of an intense central absorption with parameters typical for Fe³⁺ (ΔE _Q~0.4 mm/s, δ~0.29 mm/s), plus an apparently symmetrical Fe²⁺ doublet. This sample acquires a light-blue shade upon heating in air at about 620 K. Thermal treatments at high temperatures caused no significant changes in the MS, but the green and yellow beryl acquire a blue colour. All these results are interpreted in relation to the existence of channel water and the distribution of iron among the available crystallographic sites.  相似文献   

Typhoons and seismicity     

L. I. Morozova 《Doklady Earth Sciences》2006,410(7):1132-1135

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Alkaline magmatism and enriched mantle reservoirs: Mechanisms, time, and depth of formation     

L. N. Kogarko 《Geochemistry International》2006,44(1):3-10

Alkaline magmatism has occurred since 2.5–2.7 Ga and its abundance has continuously increased throughout the Earth’s history. Alkaline rocks appeared on the Earth with changes in the geodynamic regime of our planet, i.e., when plume tectonics was supplemented by plate tectonics. Global-scale development of plate tectonics at the Archean—Proterozoic boundary initiated subduction of already significantly oxidized oceanic crust enriched in volatiles and large-scale mantle metasomatism caused the formation of enriched reservoirs as sources of alkaline and carbonatite magmatism. Study of metasomatized mantle material showed the occurrence of traces of primary carbonatite melts, which are strongly enriched in rare elements, according to ion-microprobe analyses. The results obtained allowed us to propose a new two-stage genetic model for Ca-rich carbonatites including (1) metasomatic wehrlitization and carbonatization of mantle material and (2) partial melting of wehrlitized mantle with formation of carbonate-rich melts or three immiscible liquids (at high alkali contents), i.e., silicate, carbonatitic, and sulfide (at high sulfur activity). Original Russian Text L.N. Kogarko, 2006, published in Geokhimiya, 2006, No. 1, pp. 5–13.  相似文献   

Deformability characteristics of brazilian laterites     

Jacques De Medina  Laura M. G. Motta  João D. G. Dos Santos 《Geotechnical and Geological Engineering》2006,24(4):949-971

This paper summarizes the resilient and permanent deformation characteristics of laterite gravels, determined by cyclic loading in triaxial tests of compacted specimens. A study of laterite pavements was carried out on eight paved road sections in the state of Mato Grosso. Also reported is the influence of fine sand admixture, specimen size and soaking in two laterite samples from Roraima and Rondônia in the North of Brazil. The experimental relationships of resilient moduli against applied stresses are interpreted empirically for models what may be incorporated in a structural analysis of full depth of laterite pavement.  相似文献