Crust and upper mantle structure of the Bohemian Massif from the dispersion of seismic surface waves     

Axel Plešinger  Horst Neunhöfer  Erhard Wielandt 《Studia Geophysica et Geodaetica》1991,35(3):184-195

Summary The phase velocity dispersion of Rayleigh waves for the Moxa-Vienna (MOX-VIE) and Moxa-Kaperské Hory (MOX-KHC) profiles, and of both Rayleigh and Love waves for the Kaperské Hory-Ksi (KHC-KSP) profile have been measured and inverted into models of shearwave velocity vs. depth. The three paths cross, respectively, the central part of the Bohemian Massif, its western margin, and the Bohemian Pluton and Cretaceous. For the MOX-VIE profile mean and lower crustal shear wave velocities of 3.7 and 3.9 km/s, respectively, a mean Moho depth of 34 km, and no existence of a low-velocity layer in the lower crust were found. The model obtained for the MOX-KHC profile is characterized by a slightly lower velocity in the lower crust (3.8 km/s), by a slightly lower Moho depth (32 km), and by the appearance of a weak low-velocity channel between 55 and 140 km. The crustal section of the final model for the KHC-KSP profile agrees well with the KHKS82 model derived by Novotný from results of DSS along international profile VII. Our final Rayleigh-wave model has significantly lower shear-wave velocities down to 215 km in the mantle. A systematic difference of 0.18 km/s between the average velocities of Rayleigh and Love waves has been revealed for the depth range from 30 to 215 km. Since almost no contamination of the fundamental Love mode with higher modes has been observed, and since the investigated structure hardly contains an unresolved system of thin, alternately low- and high-velocity layers, the cause of the difference is evidently polarization anisotropy of the upper mantle beneath the Bohemian Massif. It is recommended that the discussed investigations should be supplemented with data from the fan of KSP-GRF (Gräfenberg Array, Germany) paths and from the KHC-BRG (Berggiesshübel, Germany) profile.  相似文献   

Combination of common-midpoint-refraction seismics with the generalized reciprocal method     

Dirk Orlowsky  Horst Rüter  Lothar Dresen 《Journal of Applied Geophysics》1998,39(4):221-235

A useful method for increasing the signal/noise ratio of refracted waves is Common-Midpoint (CMP)-refraction seismics. With this technique the shallow underground can be described in detail using all information (amplitude, frequency, phase characteristics) of the wavetrain following the first break (first-break phase). Thus, the layering can be determined and faults, weak zones, and clefts can be identified. This paper deals with the optimization of CMP-refraction seismics used in combination with the Generalized Reciprocal Method (GRM). Theoretical studies show a close relationship of both methods to the kinematics of wave propagation. Velocities and optimum offsets determined by the GRM can be used directly in the partial Radon transformation in CMP-refraction seismics. The integration of refracted waves leads to an increase in the signal/noise ratio but simultaneously the integration boundaries must be restricted to deal only with selective parts of the investigated refractor. The result of this process is an intercept-time section which can be converted directly to a depth section using standard refraction seismic techniques. Another possibility of depth conversion is the transformation of this intercept-time section to a `pseudo-zero-offset section', known from reflection seismics. Thus, zero-offset sections can be migrated using wave-equation techniques such as Kirchhoff migration.  相似文献   

Industrialization affects heavy metal and carbon isotope concentrations in recent Baltic Sea sediments     

Helmut Erlenkeuser  Erwin Suess  Horst Willkomm 《Geochimica et cosmochimica acta》1974,38(6):823-842

Recent sediment cores of the western Baltic Sea were analyzed for heavy metal and carbon isotope contents. The sedimentation rate was determined from radiocarbon dates to be 1.4 mm/yr. The ‘recent age’ of the sediment was about 850 yr. Within the upper 20 cm of sediment, certain heavy metals became increasingly enriched towards the surface; Cd, Pb, Zn and Cu increased 7-, 4-, 3- and 2-fold, respectively, whereas Fe, Mn, Ni and Co remained unchanged. Simultaneously, the radiocarbon content decreased by about 14 per cent. The enrichment in heavy metals as well as the decrease in the ¹⁴C-concentration during the last 130 ± 30yr parallels industrial growth as reflected in European fossil fuel consumption within that same period of time. The near-surface sediments are affected by residues released from fossil fuels at the rate of about 30 g/m² yr for the past two decades. The residues have a pronounced effect on the heavy metal and carbon isotope composition of the most Recent sediments allowing estimates to be made for sedimentation, erosion and heavy metal pollution.  相似文献   

Mobility of heavy metals in harbour sediments: an environmental aspect for the reuse of contaminated dredged sediments   总被引：3，自引：0，他引：3  

Tanja Lager  Kay Hamer  Horst D. Schulz 《Environmental Geology》2005,48(1):92-100

Different methods to determine the source strength of two harbour sediment fractions were applied and are discussed with a focus on As, Cd, Cr, Co, Cu, Mo, Ni, Pb, and Zn. Four different batch experiments were performed with both the sandy and the silty fractions of harbour sediments sampled at the disposal site for dredged material in Bremen Seehausen, north Germany. In addition to the batch experiments a modified centrifugation tube was used in order to obtain pore water from the unsaturated silty fraction. Column experiments were run with the sandy fraction of the material under saturated and unsaturated conditions, irrigated with artificial acid rain water. The results show that the legal threshold value applying to Mo and Pb is not exceeded in any of the methods applied to the sandy or the silty fractions. As for the sandy fraction, Cr and Co were also below this limit. Cd, Ni, Cu and Zn exceeded the threshold values in some of the batch experiments applied to both fractions, depending on the pH value and the elution agent used in the experiment. All results obtained from saturated column leaching were below the respective threshold values; however, it should be noted that the pH was between 7 and 8 throughout the entire experiment. This pH also applied to the unsaturated column, with the exception of the first flush. This first sample had a pH value of 3.8, which was due to sulphide oxidation at the beginning of the experiment and led to strong leaching of all the elements under study. As a consequence, arsenic, Cu and Ni values exceeded their respective threshold values.  相似文献   

Evolution of a tourmaline-bearing lawsonite eclogite from the Elekdağ area (Central Pontides,N Turkey): evidence for infiltration of slab-derived B-rich fluids during exhumation   总被引：3，自引：0，他引：3  

Rainer?AltherrEmail author  Gültekin?Topuz  Horst?Marschall  Thomas?Zack  Thomas?Ludwig 《Contributions to Mineralogy and Petrology》2004,148(4):409-425

An undated high-pressure low-temperature tectonic mélange in the Elekda area (central Pontides, N Turkey) comprises blocks of MORB-derived lawsonite eclogite within a sheared serpentinite matrix. In their outer shells, some of the eclogite blocks contain large (up to 6 cm) tourmaline crystals. Prograde inclusions in poikiloblastic garnet from a well-preserved eclogite block are lawsonite, epidote/clinozoisite, omphacite, rutile, glaucophane, chlorite, Ba-bearing phengite, minor actinolite, winchite and quartz. In addition, glaucophane, lawsonite and rutile occur as inclusions in omphacite. These inclusion assemblages document the transition from a garnet-lawsonite-epidote-bearing blueschist to a lawsonite eclogite with the peak assemblage garnet + omphacite I + lawsonite + rutile. Peak metamorphic conditions are not well-constrained but are estimated approximately 400–430°C and >1.35 GPa, based on Fe–Mg exchange between garnet and omphacite and the coexistence of lawsonite + omphacite + rutile. During exhumation of the eclogite–serpentinite mélange in the hanging wall of a subduction system, infiltration of B-rich aqueous fluids into the rims of eclogite blocks caused retrogressive formation of abundant chlorite, titanite and albite, followed by growth of tourmaline at the expense of chlorite. At the same time, omphacite I (X_Jd=0.24–0.44) became unstable and partially replaced by omphacite II characterized by higher X_Jd (0.35–0.48), suggesting a relatively low silica activity in the infiltrating fluid. Apart from Fe-rich rims developed at the contact to chlorite, tourmaline crystals are nearly homogeneous. Their compositions correspond to Na-rich dravite, perhaps with a small amount of excess (tetrahedral) boron (~5.90 Si and 3.10 B cations per 31 anions). ¹¹ B values range from –2.2 to +1.7. The infiltrating fluids were most probably derived from subducting altered oceanic crust and sediments.  相似文献   

Plötzlicher Herztod und Wetter     

Horst Josef Fladung 《Theoretical and Applied Climatology》1952,4(1):85-96

Zusammenfassung An einem Material von 100 Fällen eindeutig gesicherten Herztodes, die im Institut für Gerichtliche und Soziale Medizin in Frankfurt am Main aus einem bestimmten Bereich — Raum Frankfurt am Main — und einer bestimmten zeit—Kalenderjahre 1948 bis 1950—zur Autopsie gelangten, einerseits und den bioklimatischen Daten für den gleichen Raum und die gleiche Zeit anderseits, wurde der Zusammenhang von Herztodesfällen und Wettervorgängen mit der Wahrscheinlichkeitsüberlegung, dem Wahrscheinlichkeitsintegral und formalstatistischen Methoden überprüft. Die Auswertung ergab, daß eine starke Abhängigkeit des Herztodes vom Wettergeschehen besteht. Die Häufung der Herztodesfälle konnte für die Sammelgruppe Wetterstörungen, für labiles Aufgleiten, Warmfront mit Aufgleiten und Kaltfront mit Turbulenz ebenso eindeutig gesichert werden, wie die Verminderung der Herztodesfälle in störungsfreien Zeiten. Die hohe Wahrscheinlichkeit einer Beziehung besteht ferner für Kaltfront mit Aufgleiten und in geringerem Maße auch für Föhndurchbruch. Während bei Okklusion das Material zu einem abschließenden Urteil zu gering war, konnte bei allen übrigen Wetterlagen eine Beziehung zum plötzlichen Herztod nicht nachgewiesen werden. Auch für die Gruppen, bei denen eine enge Beziehung statistisch gesichert werden konnte, sei betont, daß die Wettervorgänge nicht die alleinige Ursache des plötzlichen Herztodes, sondern nur ein auslösendes Moment bei schon vorher schwer geschädigten Herzen darstellen.

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Summary On the basis of 100 ascertained cases of cardiac death from a certain region—province Frankfort on-the-Main—and a certain period—calendar years 1948 to 1950—, submitted to autopsy in the Institute for Legal and Social Medicine at Frankfort on-the-Main, and of bioclimatic data from the same region and period, the relation between cardiac death and meteorological phenomena was examined by means of probability considerations, the probability integral, and methods of formal statistics. Evaluation of this material showed cardiac death to be strongly dependent on weather conditions. Increase of frequency of cardiac death could be established without any doubt for the collective groups weather disturbances, unstable ascending motion, warm front with ascending motion, cold front with turbulence, whereas decrease of frequency was found in undisturbed periods. Furthermore, high probability of an existing relation was found for cold front with ascending motion and, to a lesser degree, also for foehn invasion. As to occlusion no definite conclusions could be drawn for scarcity of observations. For all the other weather types no relation to sudden cardiac death could be proved. Meteorological phenomena are by no means the only cause of sudden cardiac death, not even for the groups in which a close relation could be established statistically. They have but an initiatory effect in case of prior severe heart diseases.

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Résumé Disposant d'un matériel médical de 100 cas de mort cardiaque qui ont fait l'objet d'autopsies à l'Institut de médecine légale et sociale de Francfort sur le Mein (région de Francfort et période de 1948 à 1950), et disposant d'autre part pour la même région et pour la même période d'observations bioclimatologiques, l'auteur a étudié la relation de ces décès avec les phénomènes météorologiques à l'aide des méthodes modernes de statistique, de l'intégrale de probabilité etc. Le résultat montre une étroite dépendance centre les cas de mort cardiaque et les conditions météorologiques. On a pu vérifier sans doute possible l'augmentation des décès lors de «perturbations», d'«ascendances labiles», de «fronts chauds avec glissement ascendant», de «fronts froids avec turbulence», de même que leur diminution lors de périodes non troublées. La forte corrélation subsiste avec les «fronts froids avec ascendance» et à un moindre degré avec «l'invasion du foehn». Tandis que pour les «occlusions» le matériel disponible était trop restreint pour aboutir à une conclusion, l'examen des situations autres que les précédentes n'a pas conduit à une relation intime. Il convient de remarquer que pour tous les groupes de météores ayant donné une corrélation statistique très nette, les phénomènes météorologiques n'ont joué qu'un rôle déclancheur chez des malades déjà gravement atteints.

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Mit 2 Textabbildungen.  相似文献   

Aquifer Tuning for Optimum Performance of In Situ Remedies     

Suthan Suthersan  John Horst  Denice Nelson  Scott Potter 《Ground Water Monitoring & Remediation》2010,30(3):39-44

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Illite authigenesis in sandstones of the Guaritas Allogroup (Early Paleozoic): Implications for the depositional age,stratigraphy and evolution of the Camaquã Basin (Southern Brazil)     

Anderson José Maraschin  Ana Maria Mizusaki  Horst Zwingmann  André Weissheimer de Borba  Gesiane Fraga Sbrissa 《Journal of South American Earth Sciences》2010,29(2):400-411

Several analytical studies performed on alluvial-eolian sandstones of the Early Paleozoic Guaritas Allogroup (Camaquã Basin, southern Brazil) indicate illite to be abundant, showing different morphologies as authigenic grain rims and pore-bridging filaments. Authigenic illite separates of variable grain sizes from distinct stratigraphic intervals of the Guaritas Allogroup yielded ⁴⁰K–⁴⁰Ar ages from 521.7 ± 10.3 to 473.7 ± 9.4 Ma. These ages, interpreted to record the timing of illite authigenesis, are coincident with the age of emplacement of the Rodeio Velho andesites (470 ± 19 Ma). Moreover, field structures suggest interaction between hot, andesite lava flows and wet, poorly consolidated sediments of the Pedra Pintada Alloformation (lower strata of the Guaritas Allogroup). This set of data indicates that the Rodeio Velho volcanism could have been responsible for a widespread remobilization of interstitial fluids and consequent authigenic illite precipitation in the sandstones of the Guaritas Allogroup.  相似文献   

Activity of comets: Gas transport in the near-surface porous layers of a cometary nucleus     

Yuri V. Skorov  Rik van Lieshout  Horst U. Keller 《Icarus》2011,212(2):867-876

The gas transport through non-volatile random porous media is investigated numerically. We extend our previous research of the transport of molecules inside the uppermost layer of a cometary surface ( [Skorov and Rickman, 1995] and [Skorov et al., 2001]). We assess the validity of the simplified capillary model and its assumptions to simulate the gas flux trough the porous dust mantle as it has been applied in cometary physics. A microphysical computational model for molecular transport in random porous media formed by packed spheres is presented. The main transport characteristics such as the mean free path distribution and the permeability are calculated for a wide range of model parameters and compared with those obtained by more idealized models. The focus in this comparison is on limitations inherent in the capillary model. Finally a practical way is suggested to adjust the algebraic Clausing formula taking into consideration the nonlinear dependence of permeability on layer porosity. The retrieved dependence allows us to accurately calculate the permeability of layers whose thickness and porosity vary in the range of values expected for the near-surface regions of a cometary nucleus.  相似文献   

Geotechnical characteristics of deep-sea sediments from the North Atlantic and North Pacific oceans     

Horst G. Brandes 《Ocean Engineering》2011,38(7):835-848

Geotechnical properties from a series of deep-sea sites in the North Atlantic and North Pacific oceans are examined to evaluate overall trends and to compare with similar fine-grained soils found on land. The study areas encompass a range of sedimentary environments dominated by combinations of turbidite and pelagic deposits. Carbonate content in excess of 20% is seen to result in a decrease in liquid limit and compressibility. Vertical profiles of geotechnical properties in the North Pacific show broader changes in down-core geotechnical properties compared to the North Atlantic and reflect the effects of long-term climatic changes and seafloor spreading. Sediments in the North Atlantic indicate significant differences depending on location, which is attributed to variability in turbidite deposition, water depth, distance from sediment sources, and the effects of bottom currents. Compared to equivalent fine-grained soils on land, deep-sea sediments are generally softer, more compressible and have higher friction angles at comparable Atterberg limits. Deeper and older sediments in the North Pacific are characterized by unusually large plastic limits, which are attributed to the presence of volcanic fractions. Empirical relationships for compression index and friction angle are discussed for sediments from both oceans.  相似文献