排序方式： 共有84条查询结果，搜索用时 15 毫秒
21.
22.
Precise provenance analysis of andesite and dacite pebbles from conglomerates in the Eastern Alpine Molasse zone, using geochemical and geochronological methods, provides evidence for a synorogenic volcanic chain in the Eastern Alps which is completely eroded today. This volcanism was related to Periadriatic magmatism along the Periadriatic lineament and took place in the Palaeogene, roughly between 40 and 30 Ma. The occurrence of remnants of these volcanic rocks together with other marker lithologies in the Eastern Alpine Molasse, implies an early to middle Miocene drainage system which was, in some respects, similar to the present Inn river system, but had a considerably larger catchment area, reaching farther south. The Palaeo-Inn drained the central and eastern sections of the Periadriatic magmatic belt to the northern foreland basin. 相似文献
23.
Meghan E. Gray Christian Wolf Marco Barden Chien Y. Peng Boris Häußler Eric F. Bell Daniel H. McIntosh Yicheng Guo John A. R. Caldwell David Bacon Michael Balogh Fabio D. Barazza Asmus Böhm Catherine Heymans Knud Jahnke Shardha Jogee Eelco van Kampen Kyle Lane Klaus Meisenheimer Sebastian F. Sánchez y Taylor Lutz Wisotzki Xianzhong Zheng David A. Green R. J. Beswick D. J. Saikia Rachel Gilmour Benjamin D. Johnson Casey Papovich 《Monthly notices of the Royal Astronomical Society》2009,393(4):1275-1301
We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at z ∼ 0.165 has been the subject of an 80-orbit F606W Hubble Space Telescope (HST) /Advanced Camera for Surveys (ACS) mosaic covering the full span of the supercluster. Extensive multiwavelength observations with XMM–Newton , GALEX, Spitzer , 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction and creation of a master catalogue. We perform the Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star formation rates for this field. We define galaxy and cluster sample selection criteria, which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues. 相似文献
24.
Balázs Koroknai Péter Horváth Kadosa Balogh István Dunkl 《International Journal of Earth Sciences》2001,90(3):740-751
Petrological and geochronological investigations were carried out on metamorphic rocks of the Veporic unit (Inner Western Carpathians) in northern Hungary. K/Ar and Ar/Ar data on micas and amphibole show only Alpine ages (mostly in the range of 87-95 Ma) in this basement unit. Thermobarometric calculations yield lower amphibolite facies peak conditions (ca. 550냴 °C and 9ǃ kbar) for the Eoalpine metamorphic event. Complex evolution of gneissic rocks is reflected by the presence of discontinuously zoned garnets, the cores of which may represent relics of a pre-Alpine (presumably Variscan) thermal event. Zircon fission track (FT) data in the narrow range of 75-77.5 Ma indicate that this portion of the Veporic unit was emplaced to shallow crustal levels already during the Senonian time. The relative minor difference between zircon FT and K/Ar or Ar/Ar ages suggests very rapid cooling during the Late Cretaceous, most probably related to the extensional unroofing of the Veporic core complex. The obtained cooling ages do not support previous models of Tertiary uplift and exhumation of the Veporic unit along the Hurbanovo-Diósjeni Line. 相似文献
25.
Problems of site selection for nuclear waste disposal in a loess-covered hill environment in Hungary
Problems of the long-term storage of nuclear waste produced by the Paks power plant have recently come to the fore in Hungary. After an extensive debate between investors and the local population the decision makers took the side of those having opposed the establishment of the waste disposal site in the initially proposed environment. Several studies have been conducted to support both pros and cons. Although the idea was rejected finally, this debate has proven that comprehensive research prior to decision making is indispensable in similar cases.Regretfully, the academic staff of the GRIHAS was invited to participate in the expertise too late, in 1988, to investigate the geomorphological and social-economic environmental conditions of the proposed site. The latter cannot be neglected since the settlement pattern, demographic structure, character of economic activities, the level and state of the infrastructure — though indirectly — exert a long-term impact on the circumstances of the operation of the site, the living conditions of the people working there and on the use of the environment. Any harmful effect from the secondary wastes to be deposited could endanger the security of the local population, that is why a thorough geographical analysis based on field research in the immediate and wider surroundings of the site is necessary already in the phase of decision preparation. 相似文献
26.
Summary The distribution of strontium in 26 igneous rocks from the Tokaj Mountains, ranging from basalt to rhyolite has been determined by using stable isotope dilution techniques. The comparison with main component analytical data allows a classification of the different rock types (basalts, andesites, dacites, rhyolites) into only two distinctly separate genetic groups, which can be described schematically by independent liquid-solid fractionation processes. It is shown that alkaline metasomatism can produce Sr/Ca relationships similar to those developed in a liquid-solid fractionation process. Contamination by partial melting of crustal rocks, as well as magma contamination by transvaporizational mechanisms, results in similar changes in the Sr/Ca ratio, which therefore can be misleading in defining various stages of magma development.
With 3 Figures 相似文献
Über die Geochemie des Strontiums in tertiären Erstarrungsgesteinen des Tokaj-Gebirges
Zusammenfassung Die Strontiumverteilung in 26 Erstarrungsgesteinen des Tokaj-Gebirges wurde mit der Isotopenverdünnungsmethode bestimmt. Der Vergleich mit den chemischen Hauptkomponenten läßt die Einteilung der verschiedenen Gesteinstypen (Basalte, Andesite, Dazite, Rhyolite) in nur zwei, genetisch voneinander deutlich verschiedenen Reihen zu; diese können schematisch als voneinander unabhängige Fraktionierungsprozesse zwischen liquider und fester Phase beschrieben werden. Es wird gezeigt, daß Alkalimetasomatose Sr/Ca-Beziehungen erzeugen kann, die denen durch Liquidus/Solidus-Fraktionierung hervorgerufenen ähnlich sind. Kontamination durch partielles Aufschmelzen von Krustengesteinen und Magmenkontamination durch Transvaporisationsprosesse bewirken ähnliche Änderungen im Sr/Ca-Verhältnis; dieses kann daher bei der Definition verschiedener Stadien der Magmenentwicklung zu Fehldeutungen führen.
With 3 Figures 相似文献
27.
28.
M. W. Dunlop A. Balogh W. Baumjohann G. Haerendel K.-H. Fornacon E. Georgescu R. Nakamura S. Kokubin 《Annales Geophysicae》1999,17(12):1535-1559
Magnetic field measurements, taken by the magnetometer experiment (MAM) on board the German Equator-S spacecraft, have been used to identify and categorise 131 crossings of the dawn-side magnetopause at low latitude, providing unusual, long duration coverage of the adjacent magnetospheric regions and near magnetosheath. The crossings occurred on 31 orbits, providing unbiased coverage over the full range of local magnetic shear from 06:00 to 10:40 LT. Apogee extent places the spacecraft in conditions associated with intermediate, rather than low, solar wind dynamic pressure, as it processes into the flank region. The apogee of the spacecraft remains close to the magnetopause for mean solar wind pressure. The occurrence of the magnetopause encounters are summarised and are found to compare well with predicted boundary location, where solar wind conditions are known. Most scale with solar wind pressure. Magnetopause shape is also documented and we find that the magnetopause orientation is consistently sunward of a model boundary and is not accounted for by IMF or local magnetic shear conditions. A number of well-established crossings, particularly those at high magnetic shear, or exhibiting unusually high-pressure states, were observed and have been analysed for their boundary characteristics and some details of their boundary and near magnetosheath properties are discussed. Of particular note are the occurrence of mirror-like signatures in the adjacent magnetosheath during a significant fraction of the encounters and a high number of multiple crossings over a long time period. The latter is facilitated by the spacecraft orbit which is designed to remain in the near magnetosheath for average solar wind pressure. For most encounters, a well-ordered, tangential (draped) magnetosheath field is observed and there is little evidence of large deviations in local boundary orientations. Two passes corresponding to close conjunctions of the Geotail spacecraft are analysed to confirm boundary orientation and motion. These further show evidence of an anti-sunward moving depression on the magnetopause (which is much smaller at Equator-S). The Tsyganenko model field is used routinely to assist in categorising the crossings and some comparison of models is carried out. We note that typically the T87 model fits the data better than the T89 model during conditions of low to intermediate Kp index near the magnetopause and also near the dawn-side tail current sheet in the dawnside region. 相似文献
29.
This paper presents directional low energy solar proton measurements together with inter-planetary magnetic field measurements. Propagation of 1 to 13 MeV solar protons is discussed in terms of the relative importance of field-aligned streaming compared to convection of the proton population in the solar wind. Evidence is presented to show that protons associated with the January 24, 1969 solar flare were stored near the Sun for at least 90 minutes. It is also shown that under favourable conditions solar protons can be accelerated near the Earth's bow shock. The decay of solar protons is shown to be mainly convective; however, there are indications that in smooth field regimes convection of 1 MeV solar protons can be greatly reduced. Finally, it is pointed out that the effect of adiabatic deceleration can be quite important. 相似文献
30.
Vanja Bi?evac Erwin Krenn Dra?en Balen Fritz Finger Kadosa Balogh 《Mineralogy and Petrology》2011,102(1-4):163-180
Granitic pebbles occurring in the Permotriassic metasedimentary sequence of eastern Papuk, Slavonian Mountains, Croatia, were recognized to represent a coherent group of felsic, muscovite-albite metagranites. Fabrics, modal compositions and geochemical data imply that the rocks are derivatives of S-type granites formed through a combination of igneous and subsequent metasomatic processes. A Variscan formation age is demonstrated by K-Ar dating on coarse muscovite (range of 329?C317?Ma) as well as by electron microprobe based Th-U-Pb monazite dating (338?±?15?Ma). Additionally to the Variscan metasomatic processes of albitization and greisenisation, which led to an almost complete replacement of K-feldspar and biotite by albite and coarse muscovite, pebbles were affected by a younger phase of alteration resulting in the formation of a fine-grained sericitic matrix. The fine sericite yields K-Ar ages of 91?C83?Ma. A substantial reheating of the rocks during the Cretaceous is also indicated by the growth of new monazite dated at 106?±?10?Ma. Yttrium-contents of the Cretaceous monazite from the granite pebbles (0.3?C0.9?wt% Y2O3) are compatible with metamorphic temperatures of ~350?C400°C. These data confirm recent concepts according to which large parts of the Slavonian Mountains received a pervasive Cretaceous low-T regional metamorphic overprint. Furthermore, the pebbles provide useful information on the nature of the eroded Variscan crust of the Tisia Terrain, which has obviously contained considerable amounts of evolved high-level S-type granites modified through albitization and greisenization. 相似文献