Preface: Proceedings of the 5th International Symposium on Lithographic Limestone and Plattenkalk   总被引：1，自引：0，他引：1  

Daniel Marty  Jean-Paul Billon-Bruyat  Christian A. Meyer  Loïc Costeur  Basil Thüring 《Swiss Journal of Geoscience》2011,104(1):1-29

Magmatic rocks from the pre-Mesozoic basements of the Sambuco and Maggia nappes have been dated by U–Pb zircon ages with the LA-ICPMS technique. Several magmatic events have been identified in the Sambuco nappe. The mafic banded calc-alkaline suite of Scheggia is dated at 540 Ma, an age comparable to that of mafic rocks in the Austroalpine Silvretta nappe. The Sasso Nero peraluminous augengneiss has an age of 480–470 Ma, like many other “older orthogneisses” in Alpine basement units. It hosts a large proportion of inherited zircons, which were dated around 630 Ma, a Panafrican age indicating the Gondwanan affiliation of the Sambuco basement. The calc-alkaline Matorello pluton yielded ages around 300 Ma, similar to numerous Late Carboniferous intrusions in other basement units of the Lower Penninic (Monte Leone, Antigorio, Verampio) and Helvetic domains (Gotthard and other External Crystalline Massifs). Associated lamprophyric dykes are slightly younger (300–290 Ma), like similar dykes sampled in gneiss blocks included in the sedimentary cover of the underlying Antigorio nappe (290–285 Ma). The Cocco granodiorite and Rüscada leucogranite, both intruding the basement of the neighbouring Maggia nappe, yielded ages of ca. 300–310 Ma, identical within errors to the age of the Matorello pluton. They are significantly older than former age determinations. This age coincidence, coupled with remarkable petrologic similarities between the Cocco and Matorello granodiorites, strongly suggests paleogeographic proximity of the Sambuco and Maggia nappes in Late Carboniferous times. In recent publications these two nappes have been interpreted as belonging to distinct Mesozoic paleogeographic domains: “European” for Sambuco and “Briançonnais” for Maggia, separated by the “Valais” oceanic basin. In this case, the similarity of the Matorello and Cocco intrusions would demonstrate the absence of any significant transcurrent movement between these two continental domains. Alternatively, according to a more traditional view, Sambuco and Maggia might belong to a single large Alpine tectonic unit.  相似文献   

Remote sensing- and GIS-based runoff modeling with the effect of land-use changes (a case study of Cochin corporation)     

M. Nagarajan  George Basil 《Natural Hazards》2014,73(3):2023-2039

A study was conducted to estimate the runoff in urbanized zone using Soil Conservation Services Curve Number (SCS-CN) method through remote sensing and GIS techniques. In this study, the region was identified as Cochin Corporation (Kerala State, India) with an aerial extent of 96.44 km². The spatial and non-spatial data were collected from different sources, and the thematic layers of soil hydrologic group and land-use maps were prepared and overlaid with one other. The overlaid output results were assigned by curve numbers with respect to soil and land-use categories, and the CN map was prepared with the help of Visual Basic (VB) language in ArcGIS platform. Through supervised classifications, 13 different land-use classes were identified from Quickbird data for the year of 2005 and 2010. The most prominent land-use classes were water bodies, residential, mixed crops, commercial and industrial, and 3 types of soil hydrologic groups were identified namely A, B, and C categories. The B group is most prominent occupying 60 km² of the study area. The CN map shows the ranges that 92–100 is the major CN area with high runoff potential zone of the study region. At the final stage, the runoff was estimated by the maximum successive rainfall received in this study area in two different years—2005 and 2010 along with their land-use pattern. The runoff model is applied for temporal variation in land-use change, and impact of runoff was studied. The study area showed significant changes in land-use pattern between 2005 and 2010 particularly in the land-use change from agricultural into industrial, commercial, and residential (high density). The area covered by the highest runoff depth with the range of 92–100 CN values increased from 43.87 to 45.32 km² from 2005 to 2010. The volume of runoff was increased from 135.56 to 141.49 Mm³ from 2005 to 2010 due to the land-use change pattern.  相似文献   

Trapping of particles in a time-dependent Hamiltonian     

Basil Barbanis 《Celestial Mechanics and Dynamical Astronomy》1976,14(2):201-208

The trapping of particles in the case of two coupled oscillators, when the frequency of one approaches the constant frequency of the other exponentially in time, is investigated. It is found that we can predict the region of initial conditions for which a test particle can be trapped around a resonant periodic orbit.  相似文献   

Physical parameters of the atmosphere of Venus     

Basil Petropoulos 《Earth, Moon, and Planets》1988,42(1):29-40

The following parameters have been computed for the Cytherean atmosphere: pressure, density, speed of sound, collisional frequency, column mass, density scale, mean-free-path, viscosity, pressure scale, mean particle velocity, number density at an altitude from 0 to 170 km.The chemical composition, the temperature distribution function of the altitude, the surface pressure and the surface temperature measured by Pioneer Venus have been used as input data for these computations.  相似文献   

Small scale solar magnetic fields and their relation to various solar activity indices     

Basil P. Tritakis 《Astrophysics and Space Science》1983,93(1):141-147

Correlation studies between various solar activity indices and a long time series of annual sums of the maximum value of solar magnetic field intensity, observed for each group of sunspots during each passage of it over the visible solar hemisphere, have pointed out a couple of interesting points. First, the faculae have a significant contribution to the numerical representation of the small scale solar magnetic coefficients and low standard errors of estimation to the above mentioned maximum values of the solar magnetic field. These properties give to the area index an important physical meaning which is a first approximation to the small scale solar magnetic fields expressed by the above-mentioned maximum values of it. Finally, the main point which comes out is that long term studies of the solar magnetic fields, especially extrapolated studies to the past, could be supported by photospheric indices of the solar activity. This paper constitutes the expanded version of a report presented to theIAU Symposium No. 102 ‘Solar and Stellar magnetic fields: Origins and coronal effects’, held in Zürich 2–6 August, 1982.  相似文献   

Controls on sediment export from the Waipaoa River basin, New Zealand     

Jonathan D. Phillips  Basil Gomez† 《Basin Research》2007,19(2):241-252

A stability model of drainage basin mass balance is used to interpret historic and prehistoric patterns of sediment production, storage and output from the Waipaoa River basin, New Zealand and assess the sensitivity of basin sediment yield to land use change in the historic period. Climate and vegetation cover changed during the late Holocene, but the drainage basin mass balance system was stable before the basin was deforested by European colonists in the late 19th and early 20th centuries. In this meso‐scale dispersal system sediment sources and sinks are closely linked, and before that time there was also little variability in the rate of terrigenous mass accumulation on the adjacent continental shelf. However, despite strong first‐order geologic controls on erosion and extensive alluvial storage, sediment delivery to the continental shelf is sensitive and highly responsive to historic hillslope destabilization driven by land use change. Alluvial buffering can mask the effects of variations in sediment production within a basin on sediment yield at the outlet, but this is most likely to occur in basins where alluvial storage is large relative to yield and where the residence time of alluvial sediment is long relative to the time scale of environmental change. At present, neither situation applies to the Waipaoa River basin. Thus, the strength of the contemporary depositional signal may not only be due to the intensity of the erosion processes involved, but also to the fact that land use change in the historic period destabilized the drainage basin mass balance system.  相似文献   

Attenuation of shear-waves in the back-arc region of the Hellenic arc for frequencies from 0.6 to 16 Hz     

Antonis Polatidis  Anastasia Kiratzi  Panagiotis Hatzidimitriou  Basil Margaris 《Tectonophysics》2003,367(1-2):29-40

Q_β for shear-waves is determined for the inner part of the Hellenic arc, the back-arc area, as a function of frequency in the range 0.6–16 Hz. We used 314 digital records from 32 earthquakes with magnitudes (M_w) ranging from 3.9 to 5.1. Epicentral distances ranged from 65 to 515 km. The data were obtained in 1997 during a 6-month operation of a digital portable network in Greece. The Q_β estimates were made for five frequency bands centred at 0.8, 1.5, 3.0, 6.0 and 12.0 Hz and the Q_β values obtained were 47, 79, 143, 271 and 553, respectively. The results show that Q_β for S-waves increases with frequency taking the form Q_β=55f ^0.91 (or Q_β⁻¹0.018f^−0.91). The high attenuation and the strong frequency dependence found, which is close to the frequency dependence of coda Q for Greece, are characteristic of an area with high seismicity, rapid extension, and in agreement with other similar studies in Greece.  相似文献   

Fabric studies within the Cascade Lake shear zone, Sierra Nevada, California   总被引：1，自引：0，他引：1  

Basil Tikoff  Matthew R. Davis  Christian Teyssier  Michel de St. Blanquat  Guillaume Habert  Sven Morgan   《Tectonophysics》2005,400(1-4):209-226

The Cascade Lake shear zone occurs on the eastern margin of the Tuolumne Intrusive Suite, Sierra Nevada Batholith, California. Foliation in the zone is NNW trending and subvertical, and lineation is moderately south plunging. Deformation is syn-tectonic with emplacement of the Cathedral Peak granodiorite. A deformation gradient exists toward the NE margin of this pluton, with higher strains and lower temperatures of deformation found near the contact. We compare fabric data collected very densely in this shear zone using several techniques: field fabrics, 3D orientation of K-feldspar megacrysts, and AMS (anisotropy of magnetic susceptibility) analysis. In general, the results from the three different methods are in agreement. Deformation in this shear zone is part of a larger pattern of deformation within the Cathedral Peak granodiorite, as recorded by AMS analysis, and dextral shearing associated within the last stage of plutonism within the Sierra Nevada magmatic arc.  相似文献   

Geographical and vertical variation of the earth's seismicity     

Theodoros M. Tsapanos  Basil C. Papazachos 《Journal of Seismology》1998,2(3):183-192

Information concerning a total number of 13700 instrumentally recorded earthquakes is used to study the geographical and the vertical distribution of the Earth's seismicity. From these earthquakes, which form four complete samples of data (M 7.0, 1894–1992; M 6.5, 1930–1992; M 6.0, 1953–1992; M 5.5, 1966–1992), 11511 are shallow (h 60 km), 2085 are of intermediate focal depth (61 h 300 km) and 564 are deep focus earthquakes (301 h 720 km). The parameters a and b of the frequency-magnitude relationship were calculated in a grid of equally spaced points at 1° by using the data of earthquakes located inside circles centered at each point. The radius of the circles increased from 30 km with a step of 10 km until the information for the earthquakes located inside the circle fulfil three criteria which concern the size of the sample used to compute these parameters at each point of the grid. The results are given in a qualitative way (epicenter maps) as well as in a quantitative way (mean return periods).  相似文献   

Relationship between crustal finite strain and seismic anisotropy in the mantle, Pacific–Australia plate boundary zone, South Island, New Zealand     

Timothy A. Little  Martha K. Savage  Basil Tikoff 《Geophysical Journal International》2002,151(1):106-116

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