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101.
Guido Meinhold Dimitrios Kostopoulos Dirk Frei Felix Himmerkus Thomas Reischmann 《International Journal of Earth Sciences》2010,99(4):813-832
The Pirgadikia Terrane in northern Greece forms tectonic inliers within the Vardar suture zone bordering the Serbo-Macedonian
Massif to the southwest. It comprises Cadomian basement rocks of volcanic-arc origin and very mature quartz-rich metasedimentary
rocks. U–Pb laser ablation sector-field inductively-coupled plasma mass spectrometry analyses of detrital zircons from the
latter reveal a marked input from a Cadomian–Pan-African source with minor contribution from Mesoproterozoic, Palaeoproterozoic
and Archaean sources. The metasedimentary rocks are correlated with Ordovician overlap sequences at the northern margin of
Gondwana on the basis of their maturity and zircon age spectra. The Pirgadikia Terrane can be best interpreted as a peri-Gondwana
terrane of Avalonian origin, which was situated close to the Cadomian terranes in the Late Neoproterozoic–Early Palaeozoic,
very much like the Istanbul Terrane. The second unit investigated is the Vertiskos Terrane, which constitutes the major part
of the Serbo-Macedonian Massif in Greece. It comprises predominantly igneous rocks of Silurian age and minor metasedimentary
rocks of unknown age and provenance. U–Pb analyses of detrital zircons from a garnetiferous mica schist of the Vertiskos Terrane
indicate derivation from 550 to 1,150 Ma-old source rocks with a major Cadomian peak. This, combined with minor input of >1,950 Ma-old
zircons and the absence of ages between ca. 1.2 and 1.7 Ga suggests a NW Africa source. The protolith age of the garnetiferous
mica schist is presumably Early Ordovician. One sample of garnet-bearing biotite gneiss, interpreted as meta-igneous rock,
comprises predominantly subhedral zircons of igneous origin with late Middle Ordovician to Silurian ages. We suggest that
the rock association of the Vertiskos Terrane is part of an ancient active-margin succession of the Hun superterrane, comparable
to successions of the Austro- and Intra-Alpine Terranes. The new data of this study provide evidence of occurrences of Avalonia-
and Armorica-derived terranes in the Eastern Mediterranean and moreover help to clarify palaeogeographic reconstructions for
the peri-Gondwana realm in the Early Palaeozoic. 相似文献
102.
François Bache Speranta‐Maria Popescu Marina Rabineau Christian Gorini Jean‐Pierre Suc Georges Clauzon Jean‐Louis Olivet Jean‐Loup Rubino Mihaela Carmen Melinte‐Dobrinescu Ferran Estrada Laurent Londeix Rolando Armijo Bertrand Meyer Laurent Jolivet Gwénaël Jouannic Estelle Leroux Daniel Aslanian Antonio Tadeu Dos Reis Ludovic Mocochain Nikola Dumurdžanov Ivan Zagorchev Vesna Lesić Dragana Tomić M. Namık Çağatay Jean‐Pierre Brun Dimitrios Sokoutis Istvan Csato Gülsen Ucarkus Ziyadin Çakır 《Basin Research》2012,24(2):125-153
The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re‐visited onshore data from Italy and Turkey that lead to a new concept of a two‐step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600–900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub‐basins led to diachronous events such as the so‐called ‘Lago Mare’.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two‐step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies. 相似文献
103.
A mathematical model is proposed to simulate brackish karstic springs. Rainfall data constitutes model input information while output information is the discharge and the chloride concentration of the water versus time. The model was constructed by considering the mass and mechanical energy balance on the hydrodynamic analog, which includes three reservoirs outflowing in a tube that lies adjacent to the spring. Two reservoirs emulate the karstic system, and the third one emulates the sea. The discharge of the spring is given by the sum of the discharge of the reservoirs, and the chloride concentration by the solution of the mixing problem between the fresh and the salty water, which exists in the tube leading to the spring. The model is applied to the spring of Almiros at Heraklion, Crete, Greece. The agreement between model values and field measurements is very good for depletion periods and satisfactory for recharge periods. 相似文献
104.
Dimitrios K. Karamitros George D. Bouckovalas George P. Kouretzis 《Soil Dynamics and Earthquake Engineering》2007,27(3):200-211
Existing analytical methods for the stress analysis of buried steel pipelines at crossings with active strike-slip faults depend on a number of simplifications, which limit their applicability and may even lead to non-conservative results. The analytical methodology presented herein maintains the well-established assumptions of existing methodologies, but also introduces a number of refinements in order to achieve a more wide range of application without any major simplicity sacrifice. More specifically, it employs equations of equilibrium and compatibility of displacements to derive the axial force applied on the pipeline and adopts a combination of beam-on-elastic-foundation and elastic-beam theory to calculate the developing bending moment. Although indirectly, material and large-displacement non-linearities are also taken into account, while the actual distribution of stresses on the pipeline cross-section is considered for the calculation of the maximum design strain. The proposed methodology is evaluated against the results of a series of benchmark 3D non-linear analyses with the finite element method. It is shown that fairly accurate predictions of pipeline strains may be obtained for a wide range of crossing angles and fault movement magnitudes encountered in practice. 相似文献
105.
Heinz Wanner Stefan Brönnimann Carlo Casty Dimitrios Gyalistras Jürg Luterbacher Christoph Schmutz David B. Stephenson Eleni Xoplaki 《Surveys in Geophysics》2001,22(4):321-381
This paper aims to provide a comprehensive review of previous studies and concepts concerning the North Atlantic Oscillation. The North Atlantic Oscillation (NAO) and its recent homologue, the Arctic Oscillation/Northern Hemisphere annular mode (AO/NAM), are the most prominent modes of variability in the Northern Hemisphere winter climate. The NAO teleconnection is characterised by a meridional displacement of atmospheric mass over the North Atlantic area. Its state is usually expressed by the standardised air pressure difference between the Azores High and the Iceland Low. ThisNAO index is a measure of the strength of the westerly flow (positive with strong westerlies, and vice versa). Together with the El Niño/Southern Oscillation (ENSO) phenomenon, the NAO is a major source of seasonal to interdecadal variability in the global atmosphere. On interannual and shorter time scales, the NAO dynamics can be explained as a purely internal mode of variability of the atmospheric circulation. Interdecadal variability maybe influenced, however, by ocean and sea-ice processes. 相似文献
106.
The record of magma chamber processes in plagioclase phenocrysts at Thera Volcano,Aegean Volcanic Arc,Greece 总被引:4,自引:0,他引:4
Karen Stamatelopoulou-Seymour Dimitrios Vlassopoulos Thomas H. Pearce Craig Rice 《Contributions to Mineralogy and Petrology》1990,104(1):73-84
Lavas and pyroclastic rocks throughout the volcanic stratigraphy of the Tertiary-Quaternary volcanic complex of Thera in the Aegean island arc display inhomogenous plagioclase populations and phenocryst resorption textures, interpreted as indicative of magma mixing. Plagioclase zoning characteristics studied by Nomarski and laser interferometry techniques establish three main categories of plagioclase: (i) inherited plagioclase (nucleated in endmember prior to initial mixing event) (ii) in situ plagioclase (nucleated in mixed or hybrid magma) and (iii) xenocrystic plagioclase. Nomarski contrast images and linearized compositional zoning profiles reveal striking differences between calcic and sodic plagioclases, depending on the composition of the lava in which they are hosted. These differences reflect the contrasting effects of changes in physical-chemical parameters in basic vis-a-vis more acidic melts during magma mixing and/or influx of new magma into the subvolcanic magma chamber, as well as the influence of magma chamber dynamics on plagioclase equilibration. Variations in bulk major and trace element abundances of Thera volcanic products reflect the dominant overprint of crystal fractionation, but decoupling between major and trace element fractionation models and variations in incompatible trace element distributions are all indicative of magma mixing processes, consistent with compositional and textural zoning in plagioclases. 相似文献
107.
George Skianis Taxiarchis Papadopoulos Dimitrios Vaiopoulos Sotiris Nikolaou 《Geophysical Prospecting》1995,43(5):677-691
A new method is proposed for the quantitative interpretation of SP field data produced by a polarized ore body and simulated by an inclined sheet. The theoretical concept is based on the study of the amplitude Spectrum. It is shown that the SP amplitude Spectrum is not continuous at zero frequency; this leads to the dip angle determination of the inclined sheet. It is also shown that the SP amplitude spectrum is practically nullified at a characteristic amortization frequency that depends on the depth of the polarized body. The maximum amplitude Spectrum value of the SP gradient is used to estimate the depth to the bottom of the polarized body. Thus, the geometrical parameters h and H, the depths to the top and bottom, respectively, as well as the dip angle of the inclined sheet, can be satisfactorily determined. Some problems may arise in the determination of these parameters, affecting their accuracy, whenever unwanted frequency noise is present. 相似文献
108.
Yang Meng Hirt Christian Wu Bin Deng Xiao Le Tsoulis Dimitrios Feng Wei Wang Chang Qing Zhong Min 《Surveys in Geophysics》2022,43(4):1201-1231
Surveys in Geophysics - The harmonic correction (HC) is one of the key quantities when using residual terrain modelling (RTM) for high-frequency gravity field modelling. In the RTM technique,... 相似文献
109.
Yeudy Felipe Vargas-Alzate Vitor Silva Dimitrios Vamvatsikos Lluis Gonzaga Pujades 《地震工程与结构动力学》2022,51(1):191-212
A simplified procedure is developed to consider the azimuthal orientation of buildings when estimating seismic risk. Two square-plan reinforced concrete building models are considered as a testbed, one with similar and one with dissimilar properties along the two principal horizontal axes. The fragility of both structures is analysed using a set of ground motion records rotated to multiple incidence angles to develop orientation-dependent fragility functions. It has been observed that, re-orienting all records so that these structures have the same azimuth vis-à-vis the corresponding epicentre leads to significant differences compared to assuming random orientations. Additional results stemming from single-degree-of-freedom oscillators further confirm such findings, showing a dependence to the proximity to the faults and the level of dissimilarity in the principal horizontal axes of the structure. The end results point to a non-negligible bias in assessment studies when a structure's orientation with respect to governing rupture scenarios is not taken into account. It is shown that the median of fragility curves calculated for un-rotated incidence angles can be bias-corrected through shifted by an amount that depends on the azimuthal orientation and level of axes-dissimilarity of structures. 相似文献
110.
Examining urban sprawl in Europe using spatial metrics 总被引:1,自引:0,他引:1
Urbanisation is a global phenomenon with an important impact on the quality of human life. Europe has been widely affected by urbanisation. One of the main characteristics of urban growth is sprawl, a negative form of urban expansion, which affects large cities and most types of urban landscapes. Spatial indicators are applied to CORINE Urban Morphological Zones (UMZ) changes in order to measure urban sprawl between 1990–2000 and 2000–2006 in 24 European countries. The indicators calculate urban morphological properties such as shape, aggregation, compactness and dispersion. The results revealed that the urban areas (UMZ) increased by 146% during 1990–2006 and the urbanisation becomes more circle-shaped and less complex where mostly sprawl occurs. Moreover, urban form becomes less clumped or aggregated. Therefore, due to accelerating rates of urban sprawl, European urban planning should intensify appropriate initiatives to avoid negative impacts on human life. 相似文献