The effect of random isotropic inhomogeneities on the phase velocity of seismic waves   总被引：3，自引：0，他引：3  

S. A. Shapiro    R. Schwarz  N. Gold 《Geophysical Journal International》1996,127(3):783-794

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Mineral deposit formation in Phanerozoic sedimentary basins of north-east Africa: the contribution of weathering     

Klaus Germann  Torsten Schwarz  Mario Wipki 《International Journal of Earth Sciences》1994,83(4):787-798

The intra- and epicontinental basins in north-east Africa (Egypt, Sudan) bear ample evidence of weathering processes repeatedly having contributed to the formation of mineral deposits throughout the Phanerozoic.The relict primary weathering mantle of Pan-African basement rocks consists of kaolinitic saprolite, laterite (in places bauxitic) and iron oxide crust. On the continent, the reaccumulation of eroded weathering-derived clay minerals (mainly kaolinite) occurred predominantly in fluvio-lacustrine environments, and floodplain and coastal plain deposits. Iron oxides, delivered from ferricretes, accumulated as oolitic ironstones in continental and marine sediments. Elements leached from weathering profiles accumulated in continental basins forming silcrete and alunite or in the marine environment contributing to the formation of attapulgite/saprolite and phosphorites.The Early Paleozoic Tawiga bauxitic laterite of northern Sudan gives a unique testimony of high latitude lateritic weathering under global greenhouse conditions. It formed in close spatial and temporal vicinity to the Late Ordovician glaciation in north Africa. The record of weathering products is essentially complete for the Late Cretaceous/Early Tertiary. From the continental sources in the south to the marine sinks in the north, an almost complete line of lateritic and laterite-derived deposits of bauxitic kaolin, kaolin, iron oxides and phosphates is well documented.  相似文献   

Grenzen quantitativer Untersuchungen bei tektonischen Experimenten     

Prof. Dr. R. Hoeppener  Dr. G. Schäfer  Dr. H. -U. Schwarz  Dipl. Phys. H. Mischke 《International Journal of Earth Sciences》1978,67(3):858-879

Quantitative experimental and theoretical investigations, except basic research, should focus only to such parameters which can be measured in the field. This is shown by three examples.

1. A model of a discontinuum composed of particles, between which friction occurs during shear is presented. Even at simple shear external and internal stresses are in equilibrium; no rigid body rotation occurs. The theory is examinated experimentally.
2. In deformation experiments with clay and sand a development of anisotropy is observed, which can cause shear fractures. The orientation of the normal stress directions can be discovered from the shear sets, their angular distribution, and the rotation of the individual blocks.
3. Most folds can be traced back to the following three types, a) Similar folds, b) concentric folds, and c) box folds. b) and c) occur only near the surface and near shear planes, as shown by experiments and field observations. In all other cases the more energy-consuming similar folds are formed. Kink bands are presumably transitional between folds and shear fractures.

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Biomasseuntersuchungen am Zooplankton der ostmecklenburgischen Küstengewässer - ein Beitrag zum Eutrophiestatus. Teil 3: Hydrographie und Biomasseuntersuchungen in den Bodden von Kloster und Vitte     

S. Schwarz 《洁净——土壤、空气、水》1978,6(2):145-151

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Biologische und bakteriologische Aspekte der Abwasserreinigung im Stabilisierungsteichsystem Warnitz     

S. Schwarz  G. P. Schmidt 《洁净——土壤、空气、水》1975,3(2):173-178

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Volcanic geomorphology and tectonics of the Aeolian archipelago (Southern Italy) based on integrated DEM data   总被引：1，自引：0，他引：1  

Massimiliano FavalliM  Dávid Karátson  Roberto Mazzuoli  Maria Teresa Pareschi  Guido Ventura 《Bulletin of Volcanology》2005,68(2):157-170

The geomorphological and morphometric analysis of the sea floor topography surrounding the Aeolian Islands, South Tyrrhenian Sea, Italy, provides insights into the relationships between the volcanological evolution of the islands and their tectonic features. We constructed geomorphological maps of the submarine portions of the seven large edifices constituting the islands on the basis of a DEM with a 5 m resolution step. These maps include constructional and destructional landforms such as submarine volcanic vents located west of Lipari and north of Alicudi, and hummocky surfaces recognised north of Lipari and Salina. The latter landforms, together with the occurrence of large scars affecting the main edifices on land, suggest that sector collapses affected some islands. Geomorphological data indicate that the location of subaerial and submarine vents is strongly controlled by local tectonic structures striking WNW-ESE (Alicudi-Filicudi sector), NNW-SSE (Salina-Lipari-Vulcano sector) and NE-SW (Panarea-Stromboli sector). The islands can be divided into two groups on the basis of some morphometric parameters: a first group with a pancake-like shape, Dp/D (abrasion platform diameter/basal diameter) higher than 0.40 and H/D (total height/basal diameter) lower than 0.13, and a second group with a conical shape, characterised by Dp/D lower than 0.34 and H/D higher than 0.14. These ratios and other morphometric parameters reflect the different volcanological and structural evolution of the Aeolian Islands. The pancake-like shaped complexes have been created, in addition to their submarine stage, by extrusive and highly explosive activity, whereas the cone-shaped edifices have been characterised by effusive or moderate explosive activity.Editorial responsibility: C Kilburn  相似文献   

Experimental and theoretical bond critical point properties for model electron density distributions for earth materials     

G. V. Gibbs  D. F. Cox  K. M. Rosso  A. Kirfel  T. Lippmann  P. Blaha  K. Schwarz 《Physics and Chemistry of Minerals》2005,32(2):114-125

Generalized X-ray scattering factor model experimental electron density distributions and bond critical point, bcp, properties generated in recent studies for the earth materials stishovite, forsterite, fayalite and cuprite with high energy single crystal synchrotron X-ray diffraction data and those generated with high resolution diffraction data for coesite and senarmonite were found to be adequate and in relatively good agreement, ~5% on average, with those calculated with quantum chemical methods with relatively robust basis sets. High resolution low energy single crystal diffraction data, recorded for the molecular sieve AlPO₄-15, were also found to yield model electron density distribution values at the bcp points for the AlO and PO bonded interactions that are in relatively good to moderately good agreement with the theoretical values, but the Laplacian values of the distribution at the points for the two bonded interactions were found to be in relatively poor agreement. In several cases, experimental bcp properties, generated with conventional low energy X-ray diffraction data for several rock forming minerals, were found overall to be in poorer agreement with the theoretical properties. The overall agreement between theoretical bcp properties generated with computational quantum methods and experimental properties generated with synchrotron high energy radiation not only provides a basis for using computational strategies for studying and modeling structures and their electron density distributions, but it also provides a basis for improving our understanding of the crystal chemistry and bonded interactions for earth materials. Theoretical bond critical point properties generated with computational quantum methods are believed to rival the accuracy of those determined experimentally. As such the calculations provide a powerful and efficient method for evaluating electron density distributions and the bonded interactions for a wide range of earth materials.Dedicated to Professor Robert F. Stewart of Carnegie Mellon University on his retirement for his brilliant and original work modeling electron density distributions.  相似文献   

Evolution and structure of the Upper Rhine Graben: insights from three-dimensional thermomechanical modelling     

Michael Schwarz  Andreas Henk 《International Journal of Earth Sciences》2005,94(4):732-750

The evolution and geometry of the Tertiary Upper Rhine Graben were controlled by a continually changing stress field and the reactivation of pre-existing crustal discontinuities. A period of WNW-ESE extension in the late Eocene and Oligocene was followed by lateral translation from the early Miocene onwards. This study utilizes 3D finite element techniques to simulate extension and lateral translation on a lithospheric scale. Brittle and creep behaviour of lithospheric rocks are represented by elastoplasticity and thermally activated power-law viscoplasticity, respectively. Contact elements allocated with cohesion and frictional coefficients are used to describe pre-existing zones of weakness in the elastic-brittle field. Our results suggest that (1) extension is accommodated along listric border faults to midcrustal depth of 15–16 km. Beneath, pure shear stretching occurs without a need for localized shear zones in lower crust and upper mantle. (2) Ductile flow at midcrustal depth across the graben accounts for the pronounced halfgraben morphology. Thereby, the shape of the border faults, their frictional coefficients, and sedimentary loads have profound effects on the rate of ductile flow across the graben. (3) Horizontal extension of 8–8.5 km and sinistral displacement across the rift of 3–4 km are needed to accommodate the observed sediment thickness.  相似文献   

Geochemistry of the Submarine Gaseous Emissions of Panarea (Aeolian Islands, Southern Italy): Magmatic vs. Hydrothermal Origin and Implications for Volcanic Surveillance     

Giovanni Chiodini  Stefano Caliro  Giorgio Caramanna  Domenico Granieri  Carmine Minopoli  Roberto Moretti  Lavinia Perotta  Guido Ventura 《Pure and Applied Geophysics》2006,163(4):759-780

The marine sector surrounding Panarea Island (Aeolian Islands, South Italy) is affected by widespread submarine emissions of CO₂ -rich gases and thermal water discharges which have been known since the Roman Age. On November 3^rd, 2002 an anomalous degassing event affected the area, probably in response to a submarine explosion. The concentrations of minor reactive gases (CO, CH₄ and H₂) of samples collected in November and December, 2002 show drastic compositional changes when compared to previous samples collected from the same area in the 1980s. In particular the samples collected after the November 3^rd phenomenon display relative increases in H₂ and CO and a strong decrease in the CH₄ contents, while other gas species show no significant change. The interaction of the original gas with seawater explains the variable contents of CO₂, H₂S, N₂, Ar and He which characterize the different samples, but cannot explain the large variations of CO, CH₄ and H₂ which are instead compatible with changes in the redox, temperature and pressure conditions of the system. Two models, both implying an increasing input of magmatic fluids are compatible with the observed variations of minor reactive species. In the first one, the input of magmatic fluids drives the hydrothermal system towards atypical (more oxidizing) redox conditions, slowly pressurizing the system up to a critical state. In the second one, the hydrothermal system is flashed by the rising high-T volcanic fluid, suddenly released by a magmatic body at depth. The two models have different implications for volcanic surveillance and risk assessment: In the first case, the November 3^rd event may represent both the culmination of a relatively slow process which caused the overpressurization of the hydrothermal system and the beginning of a new phase of quiescence. The possible evolution of the second model is unforeseeable because it is mainly related to the thermal, baric and compositional state of the deep magmatic system that is poorly known.  相似文献   

Determination of the Physical Parameters of Binary Systems: A Statistical Approach     

Fabrizio Barone  Santi Mancuso  Leopoldo Milano  Guido Russo 《Astrophysics and Space Science》1998,260(4):469-491

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