Dark spots,bubbles, and shells in the lobes of extragalactic radio sources     

Wolfgang Kundt  Lakshmi Saripalli 《Journal of Astrophysics and Astronomy》1987,8(3):211-217

Based on maps of the extragalactic radio sources Cyg A, Her A, Cen A, 3C 277.3 and others, arguments are given that the twin-jets from the respective active galactic nucleus ram their channels repeatedly through thin, massive shells. The jets are thereby temporarily choked and blow radio bubbles. Warm shell matter in the cocoon shows up radio-dark through electron-scattering.  相似文献   

Transfrontier macroseismic observations of the Ml = 5.4 earthquake of February 22, 2003 at Rambervillers,France     

Michel?CaraEmail author  Wolfgang?Brüstle  Monika?Gisler  Philipp?K?stli  Christophe?Sira  Claire?Weihermüller  Jér?me?Lambert 《Journal of Seismology》2005,9(3):317-328

The 2003 Ml = 5.4 Rambervillers earthquake, north-east of France, is the largest seismic event recorded north of the Alps since the 1992 Ms = 5.3, I₀ = VII, Roermond earthquake, Netherlands. With a maximum macroseismic intensity of VI-VII EMS-98, the 2003 event was broadly felt to a distance of 300 km from the epicentre. It provides a unique opportunity to test and compare the different procedures used in France, Germany and Switzerland when evaluating macroseismic intensities. The main purpose of this paper is to present a common transfrontier macroseismic map based on the EMS-98 intensity scale. Maximum horizontal accelerations recorded in the area are compared to the intensity values, and we propose to use a differential technique to re-estimate the magnitude of the 1682 Remiremont, I₀ = VIII, earthquake, which occurred 40 km south of Rambervillers.  相似文献   

Cretaceous–Tertiary Rhenodanubian flysch wedge (Eastern Alps): clues to sediment supply and basin configuration from zircon fission-track data     

Britta Trautwein  István Dunkl  Joachim Kuhlemann  & Wolfgang Frisch 《地学学报》2001,13(5):382-393

The provenance of Cenomanian to Eocene flysch deposits accreted along the northern margin of the Eastern Alps has been investigated by means of zircon fission-track (FT) geochronology and zircon morphology. The Rhenodanubian flysch and Ybbsitz klippen zone comprise several nappes representing the Main flysch and Laab basins. The Laab basin received sediments of stable European provenance, indicated by pre-Variscan, Variscan, and Permian–Triassic zircon FT ages, and was thus located in the immediate south of the European margin. The Main flysch basin was supplied mainly from the evolving Eastern Alps and was therefore situated south of the Laab basin. Zircon populations with Permian to Jurassic cooling ages in the Main flysch basin are related to increased heat fluxes during the break-up of Pangaea and are probably derived from the northwestern part of the Eastern Alps. The dominant Cretaceous zircon FT cooling ages reflect Eoalpine metamorphism in the Austroalpine realm.  相似文献   

Long-period precursors to pP from deep-focus earthquakes: the Moho underside reflection pMP     

Thomas Schenk  Gerhard Müller  Wolfgang Brüstle 《Geophysical Journal International》1989,98(2):317-327

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Conventional and in situ geochronology of the Teplá Crystalline unit, Bohemian Massif: implications for the processes involving monazite formation     

Hilke Timmermann  Wolfgang Dörr  Erwin Krenn  Fritz Finger  Gernold Zulauf 《International Journal of Earth Sciences》2006,95(4):629-647

The Teplá Crystalline unit (TCU), western Bohemian Massif, proves highly suitable for studying the effects of differential metamorphic reworking on the U–Th–Pb systematics in monazite, as the overprint of Variscan regional metamorphism onto high-grade Cadomian paragneisses intensifies progressively towards the northwest. Although variably hampered by scarcity, small size, and low uranium contents of monazite, isotope dilution–thermal ionisation mass spectrometry of monazite from paragneisses from the garnet, staurolite, and kyanite zones of the TCU gives a narrow ²⁰⁶Pb/²³⁸U age range from 387 to 382 Ma for Variscan peak metamorphism. These data are supported by 382–373 Ma monazite ages derived from electron microprobe analyses. Inheritance of older components in grains from the central TCU imply major “resetting” of pre-Variscan monazite around 380 Ma, possibly due to widespread garnet growth during Variscan metamorphism, which led to the consumption of pre-Variscan high-Y monazite and subsequent growth of new low-Y monazite. Concordant 498–494 Ma monazite ages in a migmatitic paragneiss close to the adjacent Mariánské Lázně Complex (MLC) grew in response to metagabbro emplacement in the MLC from 503 to 496 Ma and not during either Cadomian or Variscan regional metamorphism. Backscatter imaging and electron microprobe analyses reveal that discordant monazite of the migmatite comprises a mix of various age domains that range from ca. 540 to 380 Ma. Combined evidence presented here suggests that instead of Pb loss by volume diffusion, the apparent resetting of the U–Th–Pb systematics in monazite rather involves new crystal growth or regrowth by recrystallisation and dissolution/reprecipitation.  相似文献   

Thermal characteristics of coal fires 2: Results of measurements on simulated coal fires     

Jianzhong Zhang  Claudia Kuenzer  Anke Tetzlaff  Dieter Oertel  Boris Zhukov  Wolfgang Wagner   《Journal of Applied Geophysics》2007,63(3-4):135-147

In this paper we present thermal characteristics of coal fires as measured during simulated fires under an experimental setting in Germany in July 2002. It is thus a continuation of the previously published paper “Thermal surface characteristics of coal fire 1: Results of in-situ measurement”, in which we presented temperature measurements of real subsurface coal fires in China [Zhang, J., Kuenzer, C., accepted for publication. Thermal Surface Characteristics of Coal Fires 1: Results of in-situ measurements. Accepted for publication at Journal of Applied Geophysics.]. The focus is on simulated coal fires, which are less complex in nature than fires under natural conditions. In the present study we simulated all the influences usually occurring under natural conditions in a controllable manner (uniform background material of known thermal properties, known ventilation pathways, homogeneous coal substrate), creating two artificial outdoor coal fires under simplified settings. One surface coal fire and one subsurface coal fire were observed over the course of 2 days. The set up of the fires allowed for measurements not always feasible under “real” in-situ conditions: thus compared to the in-situ investigations presented in paper one we could retrieve numerous temperature measurements inside of the fires. Single temperature measurements, diurnal profiles and airborne thermal surveying present the typical temperature patterns of a small surface-and a subsurface fire under undisturbed conditions (easily accessible terrain, 24 hour measurements period, homogeneous materials). We found that the outside air temperature does not influence the fire's surface temperature (up to 900 °C), while fire centre temperatures of up to 1200 °C strongly correlate with surface temperatures of the fire. The fires could heat their surrounding up to a distance of 4.5 m. However, thermal anomalies on the background surface only persist as long as the fire is burning and disappear very fast if the heat source is removed. Furthermore, heat outside of the fires is transported mainly by convection and not by radiation. In spatial thermal line scanner data the diurnal thermal patterns of the coal fire are clearly represented. Our experiments during that data collection also visualize the thermal anomaly differences between covered (underground) and uncovered (surface) coal fires. The latter could not be observed in-situ in a real coal fire area. Sub-surface coal fires express a much weaker signal than open surface fires and contrast only by few degrees against the background. In airborne thermal imaging scanner data the fires are also well represented. Here we could show that the mid-infrared domain (3.8 μm) is more suitable to pick up very hot anomalies, compared to the common thermal (8.8 μm) domain. Our results help to understand coal fires and their thermal patterns as well as the limitations occurring during their analysis. We believe that the results presented here can practicably help for the planning of coal fire thermal mapping campaigns — including remote sensing methods and the thermal data can be included into numerical coal fire modelling as initial or boundary conditions.  相似文献   

Palaeoecology of well-preserved coral communities in a siliciclastic environment from the Late Pleistocene (MIS 7), Kish Island, Persian Gulf (Iran): the development of low-relief reef frameworks (biostromes) in increasingly restricted environments   总被引：1，自引：0，他引：1  

Zahra Karimi Mossadegh  Justin Parker  Eberhard Gischler  Wolfgang Oschmann  David Blakeway  Anton Eisenhauer 《International Journal of Earth Sciences》2013,102(2):545-570

Major changes in community structure and depositional relief of high-latitude coral communities in the southern Persian Gulf between marine isotope stage (MIS) 7 and the present day suggest that the area has become increasingly restricted. Corals and bivalves from outcrops on Kish Island, Iran, were identified in order to interpret the Late Pleistocene palaeoenvironmental setting. U/Th disequilibrium dating was used to constrain the ages of the stratigraphic units. During MIS 7, two coral-bearing sequences were deposited on what is now Kish Island. The lower sequence is dated as MIS 7.5 and changes laterally from an assemblage dominated by Cyphastrea sp. and Platygyra daedalea in the west to one characterized by branching Montipora in the east. By contrast, the upper sequence, dated as MIS 7.1, transitions from an assemblage dominated by platy Montipora in the west to a diverse assemblage of Platygyra and other faviids in the east. The assemblages of both sequences are within a marl matrix and bounded by thin lithified mollusc-rich layers. Corals and bivalves indicate that the sequences were deposited on gentle slopes in sheltered environments less than 20 m deep. The MIS 7 deposits may be classified as coral carpets or biostromes that developed a low-relief framework. During MIS 5, coral communities were no longer framework building and are now limited to an Acropora-rich layer of coral rubble that covers large parts of the island, and two small incipient reefs with sparse faviids. Similarities between the MIS 5 and modern nearshore coral communities suggest that the environmental conditions during MIS 5 were comparable to those of today. The late Pleistocene coral carpets and non-framework coral communities of the southern Persian Gulf may serve as models for coral biostromes in the fossil record, which formed under restricted environmental conditions such as elevated terrigenous input, high turbidity, and strong seasonal changes in temperature and/or salinity.  相似文献   

Editor's note: Astron. Nachr. 9/2012     

Carsten Denker  Alex Feller  Wolfgang Schmidt  Oskar von der Lühe 《Astronomische Nachrichten》2012,333(9):789-789

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The Validity of Dynamical Models of the Solar Atmosphere     

Wolfgang Kalkofen 《Solar physics》2012,276(1-2):75-95

Important results on the structure and dynamics of the nonmagnetic solar chromosphere are based on hydrodynamic models that oversimplify either the geometry of the atmosphere or the interaction of radiation and matter. Although the observed granulation pattern is well reproduced by the three-dimensional (3D) models, oversimplification of radiative relaxation leads to the prediction of temperature fluctuations that are too high (by a factor of 10 to 100) and result in a monotonic decrease with height in the chromosphere of the horizontally and temporally averaged temperature, and hence in the prediction of absorption lines at wavelengths where only emission lines are observed on the Sun. New values of solar abundances of oxygen and other metals are based on 3D hydrodynamic models with temporal and spatial fluctuations that are far greater than those observed. These new abundances destroy the previous agreement of observed modes with acoustic eigenmodes that had been predicted for the old abundances from a solar model for which the sound speed throughout most of the Sun was determined to an accuracy of a few parts in 10⁴. One expects that, when radiative relaxation is properly accounted for, 3D models will reproduce the essential characteristics of the solar atmosphere, among them a positive temperature gradient in the outward direction and hence exclusively emission lines in the extreme ultraviolet at all times and positions in the nonmagnetic chromosphere. A?minimum characteristic length of 0.1?arcsec is identified for the solar atmosphere, below which there is no significant structure in the actual Sun, only in wave models of the Sun. This criticism does not detract from the notable success of hydrodynamic modeling to explain the mechanism by which chromospheric H_2V and K_2V bright points are formed.  相似文献   

Reconstruction of Middle to Late Quaternary sea level using submerged speleothems from the northeastern Yucatán Peninsula     

Simon D. Steidle  Sophie F. Warken  Nils Schorndorf  Julius Förstel  Andrea Schröder-Ritzrau  Gina E. Moseley  Christoph Spötl  Jeronimo Aviles  Wolfgang Stinnesbeck  Norbert Frank 《第四纪科学杂志》2021,36(7):1190-1200

We examined 14 subaerially deposited speleothems retrieved from submerged caves in the northeastern Yucatán Peninsula (Mexico). These speleothems grew during the Middle to Late Quaternary and were dated by ²³⁰Th-U techniques to provide upper depth limits for past sea levels. We report the first relative sea-level limits for Marine Isotope Stages (MIS) 11 and 6, and present new evidence for sea-level oscillations during MIS 5 and early MIS 1. For the latter periods, the origin of growth interruptions is evaluated by combining petrographic methods with trace element analyses. The MIS 5c sea-level highstand probably occurred between 103.94 ± 0.58 ka and 96.82 ± 0.42 ka and must have exceeded -10.8 m (relative to present-day local sea level). The minimum average rate of sea-level fall over a 9.4 ka-long period during the MIS 5e/5d transition is calculated from stalagmite and published coral data at 1.74 ± 0.37 m/ka. For the early Holocene, previous discrepancies with respect to a potential multimetre oscillation of local sea level were found to be challenging to reconcile with the existing speleothem data from the area.  相似文献