Die känozoische Rhyolith-Formation im mittleren Abschnitt der Anden     

Prof. Dr. Werner Zeil  Dr. Hans Pichler 《International Journal of Earth Sciences》1967,57(1):48-81

Rhyolitic to rhyodacitic volcanics of sheet-like extent, predominantly of ignimbrite-structure, form the character of vast parts of the High Cordillera between 16 and 27 degree of southern latitude. Areas of more than 150 000 km² are covered by these rocks. In same sections the thickness is over 1000 m. The emission occurred between the upper Miocene and the lower Pleistocene of systems of fissures running N/S and SE/NW, which were formed in connexion with deep faultings during the raise of the Andes. The paper shows the results of terrain-examinations; moreover it gives 20 new rock-analyses and petrological data. A mobilisation of the melts from a high level of the crust must be expected. According to the field-observations the bulk of the acidic magma has been erupted like over-boiling milk, flooding the surface with ignimbrites. Pumice deposits and some small subvolcanic intrusive bodies vary the picture. The chemical analyses show an Al-surplus, which is an evidence of the anatectic origin of these sialic acidic magmas.  相似文献   

Die Persistenz der solaren und geomagnetischen Aktivität     

Dozent Dr. K. Cehak  Dozent Dr. H. Pichler 《Meteorology and Atmospheric Physics》1969,18(1-2):147-156

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The geographies of ancient ephesus and the Artemision in Anatolia     

John C. Kraft  Helmut Bückner  Ilhan Kayan  Helmut Engelmann 《Geoarchaeology》2007,22(1):121-149

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Variance of collapse capacity of SDOF systems under earthquake excitations     

Luis Ibarra  Helmut Krawinkler 《地震工程与结构动力学》2011,40(12):1299-1314

The variance of collapse capacity is an important constituent of probabilistic methodologies used to evaluate the probability of collapse of structures subjected to earthquake ground motions. This study evaluates the effect of ground motion randomness (i.e. record‐to‐record (RTR) variability) and uncertainty in the deterioration parameters of single‐degree‐of‐freedom (SDOF) systems on the variance of collapse capacity. Collapse capacity is evaluated in terms of a relative intensity defined as the ratio of ground motion intensity to a structure strength parameter. The effect of RTR variability on the variance of collapse capacity is directly obtained by performing dynamic analyses of deteriorating hysteretic models for a set of representative ground motions. The first‐order second‐moment (FOSM) method is used to quantify the effect of deterioration parameter uncertainty. In addition to RTR variability, the results indicate that uncertainty in the displacement at the peak (cap) strength and the post‐capping stiffness significantly contribute to the variance of collapse capacity. If large dispersion of these parameters exists, the effect of uncertainty in deterioration parameters on the variance of collapse capacity may be comparable to that caused by RTR variability. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The impact of discharge change on physical instream habitats and its response to river morphology     

Christoph Hauer  Günther Unfer  Hubert Holzmann  Stefan Schmutz  Helmut Habersack 《Climatic change》2013,116(3-4):827-850

The impact of climate-induced discharge change on fish habitats, based on 1951–2008 time series, was investigated within the crystalline catchment of the Grosse Mühl River in Northern Austria. A significant trend change of air temperature, based on Mann–Whitney statistical testing, was recorded for spring 1989 (P?=?98.9 %) and summer 1990 (P?=?99.9 %). This led to a pronounced increase in summer low flow periods. Hydrodynamic-numerical (one-dimensional/two-dimensional) modelling was applied to simulate the changing habitat characteristics due to decreasing discharge in relation to various morphological patterns (riffle-pool/plane-bed reaches). Using bathymetric data, which were sampled on cross sectional measurements, we clearly determined that plane-bed reaches (featureless bed forms) are sensitive to climate-related, reduced discharge, whereas riffle-pool reaches continued to exhibit suitable physical fish habitats even under extreme low-flow conditions. The impact of the decreased summer discharge on instream habitats was strong for subadult and adult grayling which have been used as target fish species. In situ measurements in microhabitats (velocity/depth) revealed habitat suitabilities. These values were taken as biotic input for habitat evaluation on the micro scale. The findings clearly show that river morphology is a decisive parameter in terms of habitat preservation and restoration in the context of the future impacts of climate change (decreased discharge).  相似文献   

Book reviews     

Andres G. Koestler  Helmut Heuberger 《GeoJournal》1994,34(1):128-114

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Book reviews     

Helmut Brückner  U. Schweinfurth  K. Müller-Hohenstein  R. Schwäble  Fouad N. Ibrahim  Cesar N. Caviedes 《GeoJournal》1994,33(2-3):326-328

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Introduction to PSS special issue: low frequency array (LOFAR) and (extra-)solar system science     

Imke de Pater  Namir Kassim  Helmut O. Rucker 《Planetary and Space Science》2004,52(15):1174-1341

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On optimal estimates for the solutions of linear difference equations on the circle     

Helmut Rüssmann 《Celestial Mechanics and Dynamical Astronomy》1976,14(1):33-37

A linear difference equation arising in the proof of Moser's twist mapping theorem is solved and optimal estimates for the solution are established.  相似文献   

The Purpose and Age of Underwater Walls in the Bay of Elaia of Western Turkey: A Multidisciplinary Approach     

Martin Seeliger  Dominik Brill  Stefan Feuser  Melanie Bartz  Ercan Erkul  Daniel Kelterbaum  Andreas Vtt  Christina Klein  Felix Pirson  Helmut Brückner 《Geoarchaeology》2014,29(2):138-155

Pergamum (modern: Bergama) was operating an important harbour used by military forces and merchants at the city of Elaia during Hellenistic and Roman Imperial times. Harbour‐related facilities such as warehouses, breakwaters and wharfs document the importance of this harbour site not only for the Pergamenians. This paper focuses on the purpose and age of six submerged wall structures situated approximately 1 km south of the ancient closed harbour basin of Elaia. Geoelectric cross‐sections and semi‐aquatic coring near these walls failed to detect any solid basement under the walls which excludes their possible use as breakwaters or wharfs. Instead, the walls were most likely delineating and separating evaporation ponds of salt works, which compares well with similar structures from other periods and places around the Mediterranean. Combined OSL and ¹⁴C‐dating determined the construction age of the installation between the 4th and 6th centuries A.D. Subsequent (re‐)uses are likely and are in agreement with findings from archaeological surveys.  相似文献