Exchange and correlation interactions in electron-positron plasma     

A. V. Yudin  D. K. Nadyozhin 《Astronomy Letters》2003,29(3):158-162

The effect of particle-particle interaction on the adiabatic index γ for an electron-positron plasma is considered. An improved method for numerically calculating the Hartree-Fock exchange integral is presented and its relativistic asymptotics is determined. An approximation formula is derived for the correlation part of the interaction in the low-density limit. This formula includes degeneracy and the positron component.  相似文献   

Some integrable cases of the two-body problem with mass depending both on time and distance     

J. A. Docobo 《Astronomy Letters》2003,29(5):344-347

an extension of the Gylden-Meshcherskii problem when the mass depends both on time and distance between two bodies is considered. certain mass loss laws as well as the Meshcherskii position vector and time transformation are used to convert the problem into the cases with equations of motion arising from integrable potentials.  相似文献   

The investigation of the solar wind transsonic region at meter wavelengths     

N. A. Lotova  Ya. V. Nagelys 《Solar physics》1988,117(2):407-414

Radio astronomy experiments designed to probe the interplanetary plasma close to the Sun have been carried out at the wavelength = 2.92 m using the occultation method. The experiments are based on a modification of the occultation method by which the sources, in this case quasars, are used to measure the radial dependence of the apparent source size, the scattering angle (R). The radial dependence of this source size (R) reveals that an anomalous enhancement in the scattering appears at radial distances from about 16 to 30 R , which is associated with the solar wind transsonic region. It is shown by analysis of the theoretical equations that the radial profiles of both the source size (R) and the scintillation index m(R) are consistent in the near solar interplanetary medium (R 40 R ). Combining these two independent applications of the occultation method extends the range of the investigation and provides a powerful new diagnostic of the solar wind transsonic region.  相似文献   

Lithology and stratigraphy of the Ordovician facies complexes of Gornyi Altai     

V. N. Korzhnev 《Lithology and Mineral Resources》2008,43(6):596-602

In the Ordovician time, the transform margin of the Gornyi Altai region consisted of two bathymetric stages: (1) shelf and upper parts of continental slope; (2) foothills and lower parts of continental slope. The first stage includes the shallow-water facies complexes (terrigenous and terrigenous-carbonate schlieren and variegated flyschoid), while the second stage is composed of deep-water (black shale terrigenous) and subflysch gray (carbonate terrigenous) complexes. Model series of the facies complexes established in our work should be taken into account during the geodynamic analysis of fold zones.  相似文献   

Archean high-Mg monzodiorite–syenite,epidote skarn,and biotite–sericite gold lodes in the Granny Smith–Wallaby district,Australia: U–Pb and Re–Os chronometry of two intrusion-related hydrothermal systems     

Andreas G. Mueller  Gregory C. Hall  Alexander A. Nemchin  Holly J. Stein  Robert A. Creaser  Douglas R. Mason 《Mineralium Deposita》2008,43(3):337-362

The Granny Smith (37 t Au production) and Wallaby deposits (38 t out of a 180 t Au resource) are located northeast of Kalgoorlie, in 2.7 Ga greenstones of the Eastern Goldfields Province, the youngest orogenic belt of the Yilgarn craton, Western Australia. At Granny Smith, a zoned monzodiorite–granodiorite stock, dated by a concordant titanite–zircon U–Pb age of 2,665 ± 3 Ma, cuts across east-dipping thrust faults. The stock is fractured but not displaced and sets a minimum age for large-scale (1 km) thrust faulting (D2), regional folding (D1), and dynamothermal metamorphism in the mining district. The local gold–pyrite mineralization, controlled by fractured fault zones, is younger than 2,665 ± 3 Ma. In augite–hornblende monzodiorite, alteration progressed from a hematite-stained alkali feldspar–quartz–calcite assemblage and quartz–molybdenite–pyrite veins to a late reduced sericite–dolomite–albite assemblage. Gold-related monazite and xenotime define a U–Pb age of 2,660 ± 5 Ma, and molybdenite from veins a Re–Os isochron age of 2,661 ± 6 Ma, indicating that mineralization took place shortly after the emplacement of the main stock, perhaps coincident with the intrusion of late alkali granite dikes. At Wallaby, a NE-trending swarm of porphyry dikes comprising augite monzonite, monzodiorite, and minor kersantite intrudes folded and thrust-faulted molasse. The conglomerate and the dikes are overprinted by barren (<0.01 g/t Au) anhydrite-bearing epidote–actinolite–calcite skarn, forming a 600-m-wide and >1,600-m-long replacement pipe, which is intruded by a younger ring dike of syenite porphyry pervasively altered to muscovite + calcite + pyrite. Skarn and syenite are cut by pink biotite–calcite veins, containing magnetite + pyrite and subeconomic gold–silver mineralization (Au/Ag = 0.2). The veins are associated with red biotite–sericite–calcite–albite alteration in adjacent monzonite dikes. Structural relations and the concordant titanite U–Pb age of the skarn constrain intrusion-related mineralization to 2,662 ± 3 Ma. The main-stage gold–pyrite ore (Au/Ag >10) forms hematite-stained sericite–dolomite–albite lodes in stacked D2 reverse faults, which offset skarn, syenite, and the biotite–calcite veins by up to 25 m. The molybdenite Re–Os age (2,661 ± 10 Ma) of the ore suggests a genetic link to intrusive activity but is in apparent conflict with a monazite–xenotime U–Pb age (2,651 ± 6 Ma), which differs from that of the skarn at the 95% confidence level. The time relationships at both gold deposits are inconsistent with orogenic models invoking a principal role for metamorphic fluids released during the main phase of compression in the fold belt. Instead, mineralization is related in space and time to late-orogenic, magnetite-series, high-Mg monzodiorite–syenite intrusions of mantle origin, characterized by Mg/(Mg + Fe_TOTAL) = 0.31–0.57, high Cr (34–96 ppm), Ni (22–63 ppm), Ba (1,056–2,321 ppm), Sr (1,268–2,457 ppm), Th (15–36 ppm), and rare earth elements (total REE: 343–523 ppm). At Wallaby, shared Ca–K–CO₂ metasomatism and Th-REE enrichment (in allanite) link Au–Ag mineralization in biotite–calcite veins to the formation of the giant epidote skarn, implicating a Th + REE-rich syenite pluton at depth as the source of the oxidized hydrothermal fluid. At Granny Smith, lead isotope data and the Rb–Th–U signature of early hematite-bearing wall-rock alteration point to fluid released by the source pluton of the differentiated alkali granite dikes.  相似文献   

Petrochemistry of the Paleoproterozoic Udokan copper-bearing sedimentary complex     

B. N. Abramov 《Lithology and Mineral Resources》2008,43(1):37-43

The maturity of terrigenous material of the Paleoproterozoic Udokan copper-bearing sedimentary complex is considered. The average values of hydrolyzate module (HM), alumina-silica module (AM), and Pettijohn’s coefficient of maturity appreciably vary throughout the Udokan Complex. Among cupriferous sandstones, rocks of the Aleksandrovka Formation are characterized by the highest maturity, whereas rocks of the Chitkanda Formation are distinguished by the lowest maturity. The maturity of cupriferous sandstones of the Sakukan Formation corresponds to that of host rocks. The maturity of cupriferous sandstones from the Aleksandrovka Formation is much higher than that of host rocks. In the Chitkanda Formation, the cupriferous sandstones are much less mature than host rocks. Climatic conditions in provenances estimated from the Nesbitt index of chemical weathering or chemical index of alteration (CIA) may be characterized as temperate ones without prominent climatic features. Most CIA values range from 46 to 66. The formation of copper-bearing sediments was closely related to the periods of volcanic activity.  相似文献   

Glauconite from Paleogene volcano-terrigenous rocks in Western Kamchatka     

A. R. Geptner  T. A. Ivanovskaya  E. V. Pokrovskaya  N. P. Kuralenko 《Lithology and Mineral Resources》2008,43(3):228-249

It is shown that glauconite-bearing interbeds are widespread in the layer-by-layer studied sections on the Sea of Okhotsk coast (Mainach section) and Kheisliveem River valley (Kavran section), the volcanoterrigenous rocks of the Kovachin, Amanin, and Gakkhin formations of the Paleogene in western Kamchatka (Upper Eocene-Lower Oligocene boundary beds). Detailed mineralogical and structural-crystallochemical characteristics of glauconite from the Amanin Formation are presented. It is suggested that such glauconite should not be used for geochronological purposes.Some specific features of glauconite formation, particularly, the preservation of specific morphological forms at high accumulation rates of volcano-terrigenous rocks, are discussed. Possibility of the formation of glauconite with the active influence of bacterial metabolism is considered.  相似文献   

The 45th anniversary of the journal <Emphasis Type="Italic">Lithology and Mineral Resources</Emphasis>     

V. N. Kholodov 《Lithology and Mineral Resources》2008,43(4):303-306

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Some types of small clinoforms in latest continental deposits     

G. F. Ufimtsev 《Lithology and Mineral Resources》2008,43(1):76-80

Some rare types of small clinoforms found in the latest continental deposits of lowland platform and mountain regions are described. The clinoforms are represented by prodelta deposits of mountain lakes, oblique-bedded horizons of floodplain alluvium of strongly meandering rivers, thick and short lenses of mountain alluvium, and alluvium horizons of great lowland rivers with oblique bedding grading into horizontal bedding. Such structures bear information on paleogeographic, morphological, and lithodynamic features of continental sedimentation.  相似文献   

The Mordor Alkaline Igneous Complex,Central Australia: PGE-enriched disseminated sulfide layers in cumulates from a lamprophyric magma     

Stephen J. Barnes  J. A. C. Anderson  T. R. Smith  L. Bagas 《Mineralium Deposita》2008,43(6):641-662

The Mordor Alkaline Igneous Complex (MAIC) is a composite intrusion comprising a body of syenite and a funnel-shaped layered mafic–ultramafic intrusion of lamprophyric parentage, the Mordor Mafic–Ultramafic Intrusion or MMUI. The MMUI is highly unusual among intrusions of lamprophyric or potassic parentage in containing primary magmatic platinum-group element (PGE)-enriched sulfides. The MMUI sequence consists largely of phlogopite-rich pyroxenitic cumulates, with an inward dipping conformable layer of olivine-bearing cumulates divisible into a number of cyclic units. Stratiform-disseminated sulfide accumulations are of two types: disseminated layers at the base of cyclic units, with relatively high PGE tenors; and patchy PGE-poor disseminations within magnetite-bearing upper parts of cyclic units. Sulfide-enriched layers at cycle bases contain anomalous platinum group element contents with grades up to 1.5 g/t Pt+Pd+Au over 1-m intervals, returning to background values of low parts per billion (ppb) on a meter scale. They correspond to reversals in normal fractionation trends and are interpreted as the result of new magma influxes into a continuously replenished magma chamber. Basal layers have decoupled Cu and PGE peaks reflecting increasing PGE tenors up-section, due to increasing R factors during the replenishment episode, or progressive mixing of between resident PGE-poor magma and more PGE-enriched replenishing magma. The presence of PGE enriched sulfides in cumulates from a lamprophyric magma implies that low-degree partial melts do not necessarily leave sulfides and PGEs in the mantle restite during partial melting. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献