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Antonis Koroneos 《Chemie der Erde / Geochemistry》2010,70(3):221-241
The origin, evolution and geotectonic setting of the Upper Jurassic Monopigadon granitoid pluton (Chalkidiki, Central Macedonia) are studied. The pluton is composed of slightly peraluminous to peraluminous high-K calc-alkaline biotite granodiorite (BGrd), biotite granite (BGr), leucogranite (LGr) and aplites (Apl). Enclosed rocks (Enc) are mostly xenoliths, surmicaceous enclaves and biotite clots occurring frequently in BGrd and BGr. Serpentinite bodies as well as amphibolite and calc-silicate hornfelses are exposed as inliers in the pluton. The granitoids are characterized by relatively low Sr contents (<180 ppm) and low Sr/Y ratio (0.4–6.4). REE are enriched in the granitic rocks (LaCN=89–148, LuCN=6–25) and the enclaves (LaCN=19–55, LuCN=15–18). The (La/Lu)CN ratio ranges from 10.5 to 4.9 in BGrd, from 11.1 to 3.8 in BGr and from 11.3 to 25.7 in LGr. The BGrd and BGr show similar LILE-enriched, spiked patterns with negative anomalies at Ba, Ta, Nb, Sr and Ti and a positive anomaly at Pb, while the patterns of LGr show higher Ta, Nb, Sr, Ti negative and Pb positive anomalies. Sr initial isotopic ratios vary from 0.7147 to 0.7174 in BGrd, are relatively constant at 0.7105–0.7113 in BGr, and range from 0.7213 to 0.7340 in LGr, while they are lower in the enclaves (0.7087–0.7094). BGrd shows the lowest εNd values (?8.31 to ?6.43), while it ranges from ?6.11 to ?4.26 in BGr and from ?3.37 to ?0.89 in LGr. Late Triassic to Late Jurassic intrusion zircon ages are reported for the Monopigadon pluton, which is unconformably overlain by Kimmeridgian–Tithonian limestones, whereas fragments of the plutonic rocks occur in the limestones. The geochemical variability of the BGrd is reproduced by two different AFC models having the same parental magma and assimilation/fractionation ratio but different assimilated end members. Geochemical modelling suggests that the BGr variability could be reproduced by two different FC models having the same parental magma but with different fractionating assemblages. The BGrd and BGr have similar sources and they likely originated by partial melting of middle-lower crustal rocks with intermediate-basaltic compositions, such as amphibolites, andesites and basalts. Felsic garnet granulites and metapelites are candidate source rocks for LGr. It is suggested that the Monopigadon plutonic rocks originated by melting of an inhomogeneous crust in a volcanic arc environment due to the heating of mantle-derived magmas, which, however, had not mixed or mingled with the crustal melts. 相似文献
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In the present work the most characteristic mechanical and physical properties of ten Hellenic marbles were investigated. The marbles, five of which were white and the other five coloured, are the most representative ones found in Greece. Among those studied are the famous marbles of Paros and Penteli, the latter being the basic material of the Parthenon. After a rough classification and the determination of their composition, the following properties of each marble were determined: specific gravity; apparent density; behaviour in water; coefficient of thermal conductivity; coefficient of linear thermal expansion and its variation with temperature; strength in various loading forms; and dynamic modulus of elasticity as well as the resistance to frost and corrosion. All the results obtained are given in diagrammatic and tabular forms. On the basis of these results, useful conclusions regarding the utility of each marble for various applications are derived. 相似文献
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RC buildings retrofitted by converting frame bays into RC walls 总被引：1，自引：1，他引：0
Michael N. Fardis Antonis Schetakis Elias Strepelias 《Bulletin of Earthquake Engineering》2013,11(5):1541-1561
Adding concrete walls by infilling certain frame bays with reinforced concrete is popular for seismic retrofitting, but is covered by codes only if the connection of the old concrete to the new ensures monolithic behavior. To avoid penalizing the foundation of the new wall with a very high moment resistance, the new concrete should not be thicker than, or surround, the old frame members. A cost-effective connection of these members to a thin new web is proposed, alongside a design procedure and detailing that conform to current codes. Owing to practical difficulties, footings of added walls are often small and weakly connected to the other footings, hence they uplift and rock during the earthquake. The model for uplift of 3D footings consists of two pairs of nonlinear-elastic springs in a cross layout and approximates also moderate nonlinearities in the soil continuum. It is used in nonlinear, static or dynamic, analyses of three buildings with added walls. The analyses of a clean, regular 4-story building show the benefit from uplift to the added walls and a certain adverse effect on some columns but not on beams, as well as the lack of a clear positive effect of tie-beams. The application to a 7-story and a 2-story real building with extreme, yet typical, irregularities in plan and elevation exemplifies the real-life restrictions in the use of added walls and shows their limits for the improvement of seismic performance; certain deficiencies in flexure or shear remain in both and are corrected at very low cost with local fiber reinforced polymer (FRP) jackets without new analysis of the building, as FRPs do not change the member effective stiffness or moment resistance. 相似文献
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Sharp-interface (or interface) flow models with Dupuit-Forchheimer approximation are widely used to assess, to first order, an aquifer’s vulnerability to seawater intrusion (SWI) and to evaluate sustainable management options for coastal groundwater resources at the screening level. Recognising that interface flow models overestimate SWI, corrections have been proposed to account for the neglected mixing and also for the outflow through a finite gap. These corrections, however, were introduced in the context of specific studies and may not be generally applicable as proposed. The interface model is revisited, placing its corrections in the context of variable-density flow (VDF) theory, by expressing them in terms of the dimensionless parameters governing VDF in schematised (aspect ratio?=?thickness/length) homogeneous confined coastal aquifers: the coupling parameter (α), a Péclet number (Pe), and the dispersivities ratio (rα). Interfaces are compared to the 50%-salinity lines of VDF numerical solutions and regression equations are developed for estimating the outflow gap and for correcting the length of the interface (terminating with a blunted edge); the dispersion correction, which modifies the interface curvature, is restated with a variable exponent. The corrections for dispersion and for the interface length appear to be the most effective; an outflow gap is important only at small α values (strong advection relative to vertical flow due to density differences). These concepts are applied successfully to calculate the interface position in the lowermost confined sub-unit of the Coastal Plain aquifer of Israel, as an estimate of SWI. 相似文献
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Antonis J Zarkanellas 《Marine pollution bulletin》1979,10(1):11-13
Benthic studies were conducted in winter and summer 1977 in Elefsis Bay, Greece and in this report the oxygendeficient and the organic carbon fields expansion over the last few years is presented. In summer 1977 the oxygendeficient field has been increased more than two times, as compared to that existing in the summer 1973, covering an area of about 80% of the bottom of the bay. In 1977 most of the bottom consisted of sediment with more than 1% organic carbon. Comparing the results of this study with those of a previously conducted study it is found that the bottom area with organic carbon over 1% has been doubled between 1975 and 1977, covering a similar area to the oxygen-deficient field. 相似文献
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Antonis J. Zarkanellas 《Marine environmental research》1979,2(3):191-207
Benthic studies in Elefsis Bay, Greece, have shown pronounced seasonal changes in both numbers of species and of individuals. In both winter and summer, abundance and diversity were higher in the western than in the eastern part of the Bay. In summer, abundance and diversity increased in the former and sharply decreased or dropped to zero in the latter. In summer most of the bottom, with an oxygen concentration of less than 1 ml/litre, became almost azoic. With increasing oxygen concentration the numbers of species and individuals increased. The most abundant and frequent winter species were found in summer in reduced numbers at a limited number of stations, all of which were characterised by an oxygen concentration higher than 1 ml/litre.Dominance diversity (H′), as measured by the Shannon-Werner formula, and its species diversity component (d), showed wide differences both spatially and temporally, which coincided with the dissolved oxygen regimes in the Bay. The evenness component (J′) did not seem to be a reliable ‘weighting factor’ of H′ when numbers of species and individuals were low, thus necessitating caution in its use.The values of H′, J′ and d were compared with those of other areas divided into pollution zones based on purely faunistic data. Using the results of these comparisons, Elefsis Bay was divided into pollution zones which, from two in winter (subnormal and polluted), increased to three in summer when an azoic zone was formed. 相似文献
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