Fortschritte in der Stratigraphie des mährischen (ostsudetischen) Devons     

Dr. Ivo Chlupáč 《International Journal of Earth Sciences》1965,54(2):1003-1025

Zusammenfassung Die vorliegende Arbeit faßt die Ergebnisse neuer Forschungen, die während der letzten zehn Jahre durchgeführt worden sind, zusammen. Im Devon werden drei Haupttypen der Faziesentwicklung unterschieden: die Entwicklung des Mährischen Karstes (Schwellenfazies mit einer Transgression im Givet und vorwiegenden Kalksteinen), die Übergangsentwicklung (Transgression im Oberems, Schiefer im Eifel, ab Givet Kalksteine, Schiefer im Famenne) und die Drahany-Entwicklung (Transgression im Siegen — Unterems, im ganzen vorwiegend Schiefer und Initialvulkanite). Die oberdevonische Schichtenabfolge ist durchweg vollkommen und stellenweise setzt die Kalksedimentation ohne Unterbrechung vom Devon bis zur Pericyclus-Stufe des Unterkarbons fort.Die jungkaledonische Faltung hinterließ im Gebiet des mährischen Devons keine nachweislichen Spuren. Die Devontransgression drang über den älteren Untergrund von N gegen S in der Zeitspanne Unterdevon — Unterfrasne vor. Die unterdevonischen Faunen sind vorwiegend rheinischen Charakters, die eifelischen weisen eine engere Beziehung zur böhmischen (herzynischen) Devonentwicklung auf und bezeugen eine breite Faunenmigrationsmöglichkeit (eine ähnliche Lage ist auch im Falle der wärmeliebenden Flachwasserfaunen vom Givet — Frasne zu beobachten). Im höheren Oberdevon erfolgt, besonders in den Gebieten der Kalkentwicklung, eine Faziesdifferenzierung. Die grundlegende, durch den Auftritt der Kulmfazies bezeichnete Faziesänderung fällt erst ins Unterkarbon. In den nichtmetamorphosierten Devon wurde fast keine bedeutsame Diskordanz zwischen dem Devon und Unterkarbon nachgewiesen; die Faltung beider Komplexe verlief gleichzeitig erst in der sudetischen oder asturischen Phase. Die bretonische Faltungsphase kam wahrscheinlich nur im metamorphen.Devon in der Nähe des Kristallins am O- und NO-Rand des Böhmischen Massivs zustande. Die Metamorphose sowie die tektonischen Störungen des Devons nehmen im allgemeinen von O gegen W zu, was die Bedeutung der variszischen Gebirgsbildung und Metamorphose bei der Gestaltung der Einheiten besonders im NO-Teil des Böhmischen Massivs unterstreicht.

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The present paper summarizes the results of investigations carried out in these ten years. In the Devonian three main types of development have been distinguished: the development of Moravian Karst (shallow-water facies with the marine transgression in Givetian and a prevalence of limestones), the Transition development (with the transgression in Upper Emsian, and shale- [Eifelian], limestone- [since Givetian], shale- [Famennian] sedimentation) and, the Drahany development (the transgression in Siegenian-Lower Emsian, general prevalence of shales and initial volcanics). The sequence of the Upper Devonian is everywhere complete, in places carbonate sedimentation continues without break up to the Pericyclus stage of the Lower Carboniferous.The Late Caledonian folding did not leave any distinct traces in the Moravian Devonian. The Devonian transgression proceeded over the older basement from the N to the S during the time-span of Lower Devonian — Lower Frasnian. The Lower Devonian faunas have prevailingly the Rhinish character, whereas those of Eifelian show a closer relationship to the Bohemian (Hercynian) development, attesting to a possibility of wide migration of fauna (similarly as the shallow-water thermophile Givet-Frasnian faunas). During the Famennian a differenciation of facies takes place, particularly in the areas of limestone development. In the sections paleontologically well evidenced the main facies change expressed by the onset of the Culm facies does not occur before the Lower Carboniferous. In the unmetamorphosed Devonian no unconformity between the Devonian and Lower Carboniferous has anywhere been proved, both the units were folded simultaneously in the Sudetic or Asturian phase. The Bretonian folding can be postulated only for the metamorphosed Devonian complexes occurring near to the marginal crystalline areas in the E and NE of the Bohemian Massif. There, also the facies change (beginning of flysch sedimentation) started probably sooner. The degree of metamorphism and tectonic disturbance generally increases from the E to the W, which emphasizes the significance of Variscan orogeny and metamorphism for the development of geological units, particularly in the north-eastern part of the Bohemian Massif.

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Résumé L'article résume les nouveaux résultats des recherches entreprises au cours des dix années dernières. Dans le Dévonien trois types principaux du développement de faciès furent distingués: celui du Karst de Moravie (faciès géoanticlinal avec transgression pendant le Givétien et la prédominance de calcaires), celui de transition (transgression pendant l'Emsien supérieur, schistes de l'Eifelien, calcaires depuis le Givétien, schistes au Famennien) et le développement de Drahany (transgression pendant le Siegénien — Emsien inférieur, prédominance générale des schistes et des volcanites initiaux). La succession du Dévonien supérieur est partout complète et par endroits la sédimentation des calcaires se poursuit sans lacune depuis le Dévonien jusqu'à l'étage Pericyclus du Carbonifère inférieur. Dans la région du Dévonien de Moravie le jeune plissement Calédonien n'a pas laissé de traces prouvables. La transgression dévonienne avançait sur le socle plus ancien dans la direction nord—sud pendant l'intervalle Dévonien inférieur — Frasnien inférieur. Les faunes du Dévonien inférieur ont pour la plupart un caractère rhénan, les faunes eifeliennes se trouvent en relation plus étroite avec le développement tchèque (hercynien) du Dévonien et prouvent la possibilité d'une migration de faunes étendue (une situation analogue existe chez les faunes néritiques thermophiles giveto-frasniennes). Dans le Famennien il se produit, surtout dans les régions du développement calcaire, une différentation de faciès. Le changement des faciès principaux, marqué par le début du faciès culmien, appartient, dans les profils mieux vérifiés du point de vue paléontologique, jusqu'au Carbonifère inférieur. Dans le Dévonien non métamorphosé une discordance entre le Dévonien et le Carbonifère inférieur ne fut prouvée nulle part; le plissement simultané des deux formation n'avait lieu que dans la phase sudétienne ou asturienne. Le plissement de la phase bretonienne se produisait probablement seulement au Dévonien métamorphisé à la proximité du Cristallin à la périphérie est ou sud-est du Massif de Bohême, où même le changement de faciès (commencement de la sédimentation du flysch) avait probablement commencé plus tôt. Le métamorphisme et les accidents tectoniques du Dévonien s'accroissent en général dans la direction est—ouest, ce qui souligne la signification de l'orogénèse et du métamorphisme varisque pendant la formation des unités, surtout dans la partie nord—est du Massif de Bohême.

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Sul carattere delle tempeste ionosferiche osservate a Buenos Aires     

Prof. Dr. Ivo Ranzi 《Pure and Applied Geophysics》1952,23(1):60-64

Riassunto L'A. espone in forma sintetica i risultati di uno studio sulle caratteristiche delle perturbazioni ionosferiche in Buenos Aires. Durante i mesi invernali la fase positiva delle perturbazioni nella regione F2 appare notevolmente ampia e si nota una stretta correlazione negativa fra la foF2 e la componente orizzontale del campomagnetico terrestre.

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Summary The Author reports synthetically the results of an investigation concerning the characteristics of ionospheric storms at Buenos Aires. In winter, the positive phase of the storms in the F2 region appears considerably large, and a close negative correlation is observed between the foF2 and the horizontal component of the terrestrial magnetic field.

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The origin of shallow landslides in Moravia (Czech Republic) in the spring of 2006     

Michal Bíl  Ivo Müller 《Geomorphology》2008,99(1-4):246-253

At the end of March 2006, the Czech Republic (CZ) witnessed a fast thawing of an unusually thick snow cover in conjunction with massive rainfall. Most watercourses suffered floods, and more than 90 shallow landslides occurred in the Moravian region of Eastern CZ, primarily in non-forested areas. This region, geologically part of the Outer Western Carpathians, is prone to landslides because the bedrock is highly erodible Mesozoic and Tertiary flysch.The available meteorological data (depth of snow, water equivalent of the snow, cumulative rainfall, air and soil temperatures) from five local weather stations were used to construct indices quantitatively describing the snow thaw. Among these, the Total Cumulative Precipitation (TCP) combines the amount of water from both thawing snow and rainfall. This concurrence of rain and runoff from snow melt was the decisive factor in triggering the landslides in the spring.The TCP index was applied to data of snow thaw periods for the last 20 years, when no landslides were recorded. This was to establish the safe threshold of TCP without landslides. The calculated safe threshold value for the region is ca. 100 mm of water delivered to the soil during the spring thaw (corresponding to ca. 11 mm day^− 1). In 2006, 10% of the landslides occurred under or at 100 mm of TCP. The upper value of 155 mm covered all of the landslides.  相似文献   

Earthquakes in Switzerland and surrounding regions during 2003     

Nicolas Deichmann  Manfred Baer  Jochen Braunmiller  Cécile Cornou  Donat Fäh  Domenico Giardini  Monika Gisler  Sarah Huber  Stephan Husen  Philipp Kästli  Urs Kradolfer  Martin Mai  Silvio Maraini  Ivo Oprsal  Thomas Schler  Danijel Schorlemmer  Stefan Wiemer  Jochen Wössner  Adrian Wyss 《Eclogae Geologicae Helvetiae》2004,97(3):447-458

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Stable isotope study of cave percolation waters in subtropical Brazil: Implications for paleoclimate inferences from speleothems     

Francisco W. Cruz  Jr.  Ivo Karmann  Oduvaldo Viana  Jr.  Stephen J. Burns  Jos A. Ferrari  Mathias Vuille  Alcides N. Sial  Marcelo Z. Moreira 《Chemical Geology》2005,220(3-4):245-262

We analyze the interannual monthly variability of oxygen isotope ratios in data from IAEA stations along the Atlantic coast of South America between 23° and 34° S to evaluate the influence of parameters such as temperature, rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical Brazil. In addition, a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the Santana Cave System (24°31′ S; 48°43′ W), is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water δ¹⁸O.

Interannual monthly variations in δ¹⁸O of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer (negative values of δ¹⁸O) to a more extratropical regime in winter (positive values of δ¹⁸O). Variations in groundwater δ¹⁸O indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters, regardless of location of collection in the cave. In addition, the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs. Significant perturbations in the groundwater composition, characterized by more positive values of δ¹⁸O, are probably connected to an increased Atlantic moisture contribution associated with extratropical precipitation. This implies that the δ¹⁸O of speleothems from caves in this region may be a suitable proxy for studying tropical–extratropical interactions over South America, a feature that is intrinsically related to the global atmospheric circulation.  相似文献   

In situ measurements of sediment settling characteristics in floodplains using a LISST‐ST     

Ivo Thonon  Johannes R. Roberti  Hans Middelkoop  Marcel van der Perk  Peter A. Burrough 《地球表面变化过程与地形》2005,30(10):1327-1343

Due to a lack of data on settling velocities (w_s) and grain size distributions (GSDs) in ?oodplain environments, sedimentation models often use calibrated rather than measured parameters. Since the characteristics of suspended matter differ from those of deposited sediment, it is impossible to derive the w_s and GSD from the latter. Therefore, one needs to measure in situ suspended sediment concentrations (SSCs), settling velocities, effective grain sizes and sedimentation ?uxes. For this purpose we used the LISST‐ST, a laser particle sizer combined with a settling tube. In 2002 (twice) and 2004, we located the LISST‐ST with an optical backscatter sensor and sediment traps in two ?oodplains in The Netherlands: one along the unembanked IJssel River, another along the embanked Waal River. Measurements revealed that the SSC in the ?oodplains varied in relation to the SSC in the river channel. Smaller ?ocs dominated the SSC, while larger ?ocs dominated the potential sedimentation ?uxes. The in situ GSD in the IJssel ?oodplain was signi?cantly coarser than in the Waal ?oodplain, while the dispersed median grain sizes were equal for both ?oodplains. Therefore, the dispersed median grain size was two to ?ve times smaller than the effective one. The in situ grain size exhibited a signi?cant positive relationship with w_s, although the w_s for the largest ?ocs showed high variability. Consequently, the variability in sedimentation ?uxes was also large. In the actual sedimentation ?uxes, and hence in sedimentation models, in situ grain sizes up to about 20 µm can be neglected. In ?oodplain sedimentation models the relation between settling velocity and in situ grain size can be used instead of Stokes's law, which is only valid for dispersed grain sizes. These models should also use adequate data on ?ow conditions as input, since these strongly in?uence the suspended sediment characteristics. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Lamellar pyroxenes and their petrogenetic significance: Three examples from the Czech Massif     

Ivo Šanc  Milan Rieder 《Contributions to Mineralogy and Petrology》1983,84(1):73-83

The first event in the crystallization of pyroxenite in nodules from Bory was the growth of clinopyroxene at an uncertain 1,190(30)° C and 2.5(2)GPa. Lamellae of garnet and orthopyroxene in CPX nucleated slightly above 1,000° C and equilibrated at 940(20)° C and 3.9(6)GPa. The growth of lamellae was followed by crystallization of groundmass that corroded lamellar clinopyroxene. Phenocrysts of clinopyroxene and orthopyroxene in olivine pyroxenite from T?i Studně crystallized at 1,290(100)° C and 2.3(1.4)GPa. The lamellae in both phases nucleated between 1,400 and 1,200° C and equilibrated at 860(40)° C and 0.2(3)GPa, before regional metamorphism. (The temperatures of nucleation mentioned rest on uncertain assumptions in the phase-boundary theory and should be viewed with caution.) The serpentinized peridotite-pyroxenite from De?tná contains clinopyroxene relics (the only primary phase) with lamellae of a 1.42 nm sheet silicate topotactically pseudomorphing enstatite, possibly a chlorite or vermiculite. All phases in lamellae are crystallographically oriented in the hosts. The present cases suggest that when applying the theory of phase boundaries, a modified procedure of Robinson et al. should also be considered, in which identity of adjacent areas, rather than just vectors, is the basis of calculation. Spinel lamellae in CPX are bounded not only by faces parallel to coherent interfaces, but also by faces formed by accumulation of incoherent edges of growth ledges.  相似文献   

Verbessertes Unpersönliches Mikrometer für Das Zirkumzenital     

Ivo Baueršíma  Josef Šuráň 《Studia Geophysica et Geodaetica》1963,7(3):209-227

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Justice for climate loss and damage     

Ivo Wallimann-Helmer 《Climatic change》2015,133(3):469-480

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A New Pseudo-dynamic Approach for Seismic Active Soil Thrust   总被引：2，自引：0，他引：2  

Ivo Bellezza 《Geotechnical and Geological Engineering》2014,32(2):561-576

A critical review of the existing pseudo-dynamic approach is provided and a new pseudo-dynamic approach is proposed based on a visco-elastic behavior of backfill overlying rigid bedrock subjected to harmonic horizontal acceleration. Considering a planar failure surface, closed form expressions for seismic active soil thrust, soil pressure distribution and overturning moment are obtained. The results of this study indicate that the existing pseudo-dynamic method can strongly underestimate the soil active thrust especially close to the fundamental frequency of the backfill, where the soil response is more sensitive to the damping ratio. The acting point of the total seismic active thrust is always found to be higher than that predicted by the traditional pseudo-dynamic approach. The effect of the shear resistance angle and wall friction angle on the acting point increases as the amplitude of the base acceleration increases, whereas their effect is generally small far from the natural frequencies of the backfill.  相似文献