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   

Managanese and iron in the White Sea: Sedimentation and diagenesis     

A. G. Rozanov  I. I. Volkov  N. M. Kokryatskaya  M. V. Yudin 《Lithology and Mineral Resources》2006,41(5):483-501

Iron and manganese in bottom sediments studied along the sublatitudinal transect from Kandalaksha to Arkhangelsk are characterized by various contents and forms depending on sedimentation environments, grain size of sediments, and diagenetic processes. The latter include redistribution of reactive forms leading to enrichment in Fe and Mn of the surface sediments, formation of films, incrustations, and ferromanganese nodules. Variations in the total Fe content (2–8%) are accompanied by changes in the concentration of its reactive forms (acid extraction) and the concentration of dissolved Fe in the interstitial water (1–14 μM). Variations in the Mn content in sediments (0.03–3.7%) and the interstitial water (up to 500 μM) correspond to a high diagenetic mobility of this element. Changes in the valence of chemical elements results in the redox stratification of sediment strata with maximum concentrations of Fe, Mn, and sulfides. Organic matter of sediments with a considerable terrestrial constituent is oxidized by bottom water oxygen mainly at the sediment surface or in anaerobic conditions within the sediment strata. The role of inorganic components in organic matter oxidation changes from surface sediments, where manganese oxyhydroxide dominates among oxidants, to deeper layers, where sulfate of interstitial water serves as the main oxidant. Differences in river runoff and hydrodynamics are responsible for geochemical asymmetry of the transect. The deep Kandalaksha Bay serves as a sediment trap for manganese (Mn content in sediments varies within 0.5–0.7%), whereas the sedimentary environment in the Dvina Bay promotes its removal from sediments (Mn 0.05%).  相似文献   

Effect of temperature and pressure on the composition of oils from the Bazhenovskaya Formation in the latitudinal segment of the Ob River area     

O. F. Stasova  A. I. Larichev  N. I. Larichkina 《Geochemistry International》2006,44(9):925-934

Detailed data obtained on surface oil samples from the Bazhenovskaya Formation in the latitudinal segment of the Ob River area indicate that the composition of the oil is largely controlled by the P-T conditions in the reservoir. It was determined that the generation of hydrocarbon fluids starts at higher temperatures (T _f > 100°C) if the fluid reflux is hindered and the formation pressures are anomalously high. In systems with the free reflux of hydrocarbon fluids, the processes generating oil and gas are different. The composition of oil in the Bazhenovskaya Formation with the free reflux of hydrocarbon fluids is largely controlled by migration processes, which determine, along with the P-T parameters, the physicochemical characteristics of the oils and their concentrations of hydrocarbon groups and individual hydrocarbons. Original Russian Text ? O.F. Stasova, A.I. Larichev, N.I. Larichkina, 2006, published in Geokhimiya, 2006, No. 9, pp. 996–1005.  相似文献   

The late visean-serpukhovian stage in paleozoic reef formation     

V. G. Kuznetsov  A. I. Antoshkina 《Stratigraphy and Geological Correlation》2006,14(2):223-223

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On two types of metalliferous carbonaceous rocks     

I. N. Tomson  O. P. Polyakova  V. Yu. Alekseev  V. A. Baskina 《Geology of Ore Deposits》2006,48(1):74-76

Two types of metalliferous carbonaceous rocks that differ in associated metals are considered. One of them is characterized by gold occurring in finely dispersed arsenopyrite and arsenic-bearing pyrite, and the other, by finely impregnated native metals in carbonaceous matter. Rocks of the first type also contain elements of the platinum group, while those of the second type bear rhenium, silver, iron, molybdenum, and other metals. Graphitic mineralization is usually localized in the shear zone associated with alkaline basalts.  相似文献   

Typhoons and seismicity     

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

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The evolution of groundwater in the Tyrrell catchment, south-central Murray Basin, Victoria, Australia     

B. Petrides  I. Cartwright  T. R. Weaver 《Hydrogeology Journal》2006,14(8):1522-1543

The Tyrell catchment lies on the western margin of the Riverine Province in the south-central Murray Basin, one of Australia’s most important groundwater resources. Groundwater from the shallow, unconfined Pliocene Sands aquifer and the underlying Renmark Group aquifer is saline (total dissolved solids up to 150,000 mg/L) and is Na-Cl-Mg type. There is no systematic change in salinity along hydraulic gradients implying that the aquifers are hydraulically connected and mixing during vertical flow is important. Stable isotopes (¹⁸O+²H) and Cl/Br ratios indicate that groundwater is entirely of meteoric origin and salts in this system have largely been derived by evapotranspiration of rainfall with only minor halite dissolution, rock weathering (mainly feldspar dissolution), and ion exchange between Na and Mg on clays. Similarity in chemistry of all groundwater in the catchment implies relative consistency in processes over time, independent of any climatic variation. Groundwater in both the Pliocene Sands and Renmark Group aquifers yield ages of up to 25 ka. The Tyrrell Catchment is arid to semi-arid and has low topography. This has resulted in relatively low recharge rates and hydraulic gradients that have resulted in long groundwater residence times.  相似文献   

The ICP-MS determination of rare earths and other metals in Baikal crude oil: Comparison with crude oils in Siberia and the Russian Far East     

T. A. Yasnygina  Yu. M. Malykh  S. V. Rasskazov  S. P. Primina  T. I. Zemskaya  O. M. Khlystov 《Doklady Earth Sciences》2006,411(8):1237-1240

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Energy transfer among Pb, Ce and Mn in fluorescent calcite from Kuerle, Xinjiang, China     

Aierken Sidike  X.-M. Wang  Alifu Sawuti  H.-J. Zhu  I. Kusachi  N. Yamashita 《Physics and Chemistry of Minerals》2006,33(8-9):559-566

Natural calcite from Kuerle, Xinjiang, China, shows orange-red fluorescence when exposed to short-wave ultraviolet (UV) light (Hg 253.7 nm). Photoluminescence (PL) emission and excitation spectra of the calcite are observed at room temperature in detail. The PL emission spectrum under 208 nm excitation consists of three bands: two UV bands at 325 and 355 nm and an orange-red band at 620 nm. The three bands are ascribed to Pb²⁺, Ce³⁺ and Mn²⁺, respectively, as activators. The Pb²⁺ excitation band is observed at 243 nm, and the Ce³⁺ excitation band at 295 nm. The Pb²⁺ excitation band is also observed by monitoring the Ce³⁺ fluorescence, and the Pb²⁺ and Ce³⁺ excitation bands, in addition to six Mn²⁺ excitation bands, are also observed by monitoring the Mn²⁺ fluorescence. These indicate that four types of the energy transfer can occur in calcite through the following processes: (1) Pb²⁺ → Ce³⁺, (2) Pb²⁺ → Mn²⁺, (3) Ce³⁺ → Mn²⁺ and (4) Pb²⁺ → Ce³⁺ → Mn²⁺.  相似文献   

Integrated radio luminosities of pulsars     

I. F. Malov  O. I. Malov 《Astronomy Reports》2006,50(6):483-495

The integrated radio luminosities of 311 long-period (P > 0.1 s) and 27 short-period (P < 0.1 s) pulsars have been calculated using a new compilation of radio spectra. The luminosities are in the range 10²⁷ ? 10³⁰ erg/s for 88% of the long-period pulsars and 10²⁸ ? 10³¹ erg/s for 88% of the short-period pulsars. We find a high correlation between the luminosity L and the estimate L ₁ = S ₄₀₀ d ² from the catalog of Taylor et al. The factor η for the transformation of the rotational energy of the neutron star into radio emission increases-decreases with increasing period for long-period and short-period pulsars. The mean value of η is ?3.73 for the long-period and ?4.85 for short-period pulsars. No dependence was found between L and the pulsar’s kinematic age t _k = |z|/〈v _z〉, where |z| and 〈v _z〉 = 300 km/s are the pulsars’ height above the plane of the Galaxy and mean velocity. A dependence of L on the rate of rotational energy losses ? was found for both groups of pulsars. It is shown that L ∝ ? ^1/3 for the entire sample. The pulsar luminosity function is constructed, and the total number and birth rate of pulsars in the Galaxy are calculated.  相似文献