Afro-arabian geology: A kinematic view,Robert Bowen and Ulrich Jux,Chapman & Hall,London, 1987. No. of pages: 295     

Andrew Watson 《地球表面变化过程与地形》1989,14(5):455-456

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Diffusion of Sm,Sr, and Pb in fluorapatite     

E.Bruce Watson  T.Mark Harrison  F.James Ryerson 《Geochimica et cosmochimica acta》1985,49(8):1813-1823

Diffusion coefficients for Sm, Sr, and Pb in fluorapatite at 900°–1250°C were obtained by measuring experimentally-induced diffusional uptake profiles of these elements in the margins of gem-quality apatite crystals. The crystals were immersed in synthetic melts enriched in the trace elements of interest and presaturated in apatite, and the resulting diffusion gradients were characterized by electron microprobe analysis. Except in the case of Pb, the diffusivities define good Arrhenius lines for the respective elements: D_Sm = 2.3 × 10^?6exp(?52,200/RT) D_Sr = 412 exp(?100,000/RT). (Diffusion perpendicular to and parallel to c is measurably different in the case of Sr; the Arrhenius equation given above is an average for the two directions). Results on Pb were erratic, probably because extremely Pb-rich melts were used for some of the experiments. Data believed to be reliable define the following Arrhenius line: D_Pb = 0.035 exp(?70,000/RT). Constraints based on closure of natural apatites with respect to Pb suggest that the experimental data can be extrapolated, with sizeable uncertainty, to temperatures as low as 550°C.When applied to the question of isotopic and trace-element equilibration of residual or entrained apatites with crustal melts, the measured diffusivities indicate that 0.05-cm crystals will rarely preserve the original Pb-isotope characteristics of the source; the same is not true, however, of Sr (and, under some conditions, the REE), which may be unaffected at crystal cores during typical melting events.  相似文献   

Triangle based interpolation     

D. F. Watson  G. M. Philip 《Mathematical Geosciences》1984,16(8):779-795

Triangle based interpolation is introduced by an outline of two classical planar interpolation methods, viz. linear triangular facets and proximal polygons. These are shown to have opposite local bias. By applying cross products of triangles to obtain local gradients, a method designated “slant-top proximal polygon interpolation” is introduced that is intermediate between linear facets and polygonal interpolation in its local bias. This surface is not continuous, but, by extending and weighting the gradient planes, a C¹ surface can be obtained. The gradients also allow a roughness index to be calculated for each data point in the set. This index is used to control the shape of a blending function that provides a weighted combination of the gradient planes and linear interpolation. This results in a curvilinear, C¹,interpolation of the data set that is bounded by the linear interpolation and the weighted gradient planes and is tangent to the slant-top interpolation at the data points. These procedures may be applied to data with two, three, or four independent variables.  相似文献   

Distribution of partial melt in a felsic system: the importance of surface energy   总被引：2，自引：0，他引：2  

Stephen R. Jurewicz  E. Bruce Watson 《Contributions to Mineralogy and Petrology》1984,85(1):25-29

The texture, distribution, and infiltration tendency of a quartz-albite melt in equilibrium with a synthetic, texturally-equilibrated quartzite was examined in a series of distribution and infiltration experiments at 1,250° C and 8 kbar hydrostatic pressure. Wetting angle measurements from melt distribution experiments show a dihedral angle () of 60 degrees, implying a quartz/quartz interfacial energy approximately 1.7 times the quartz/melt value. Because of this specific relationship between interfacial energies, the system can achieve its lowest surface free energy state with the melt either in pools or along grain edge intersections, possibly forming some interconnected channels. Stability of melt in pockets and along grain edge intersections was observed in a fourteen-day, dispersed-melt experiment, yet melt pools failed to disperse into the quartzite during infiltration experiments. Comparison of the observed dihedral angle with previously measured surface energy values for the melt and quartz shows excellent agreement, and also demonstrates that an aggregate of randomly orientated anisotropic grains acts approximately isotropically.While these experiments are not strictly applicable to real crustal systems, they do indicate that, at least in some felsic systems, the melt has no preference for uniform grainedge wetting relative to collection at grain corners or in large pools. This ambivalent behavior is attributable to the 60-degree wetting angle, which has been shown to separate systems in which melt tends to disperse in interconnected channels (<60°) from those in which melt tends to become isolated at grain corners (> 60°).  相似文献   

Smoothing and interpolation by kriging and with splines   总被引：1，自引：0，他引：1  

G. S. Watson 《Mathematical Geology》1984,16(6):601-615

Let scalar measurements at distinct points x₁, , x_n be y₁, , y_n.We may look for a smooth function f(x)that goes through or near the points (x_i, y_i).Kriging assumes f(x)is a random function with known (possibly estimable) covariance function (in the simplest case). Splines assume a definition of the smoothness of a nonrandom function f(x).An elementary explanation is given of the fact that spline approximations are special cases of the solution of a kriging problem.  相似文献   

Badland dynamics in the Central Pyrenees: temporal and spatial patterns of weathering processes     

E. Nadal‐Romero  D. Regüés  C. Martí‐Bono  P. Serrano‐Muela 《地球表面变化过程与地形》2007,32(6):888-904

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Factors influencing the release of dissolved organic carbon and dissolved forms of nitrogen from a small upland headwater during autumn runoff events   总被引：1，自引：0，他引：1  

Richard Cooper  Vera Thoss  Helen Watson 《水文研究》2007,21(5):622-633

We identify and assess the relative importance of the principal factors influencing the release of dissolved organic carbon (DOC) and dissolved forms of nitrogen (N) from a small upland headwater dominated by podzolic soils during a sequence of autumn runoff events. We achieve this by subjecting high‐resolution hydrometeorological and hydrochemical data to an R‐mode principal component factor analysis and a stepwise multivariate regression analysis. We find that the release of DOC and N is influenced by four principal factors, namely event magnitude, soil water flow through the Bs horizon, the length of time since the soil profile was last flushed, and rewetting of the H horizon. The release of DOC and dissolved organic nitrogen (DON) is most strongly influenced by the combination of event magnitude and soil water flow through the Bs horizon, and to a lesser extent by the length of time since the soil profile was last flushed. Rewetting of the H horizon also influences the release of DOC, but this is not the case for DON. The release of nitrate (NO₃‐N) is most strongly influenced by the combination of the length of time since the soil profile was last flushed and rewetting of the H horizon, and to a lesser extent by event magnitude. Soil water flow through the Bs horizon does not influence the release of NO₃‐N. We argue that the mechanisms by which the above factors influence the release of DOC and N are probably strongly associated with moisture‐dependent biological activity, which governs the turnover of organic matter in the soil and limits the availability of NO₃‐N in the soil for leaching. We conclude that the release of DOC and N from upland headwaters dominated by podzolic soils is largely controlled by the variable interaction of hydrometeorological factors and moisture‐dependent biological processes, and that a shift in climate towards drier summers and wetter winters may result in the release of DOC and N becoming increasingly variable and more episodic in the future. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Baade-Wesselink and related techniques for mode discrimination in nonradial stellar pulsations     

P. A. Stamford  R. D. Watson 《Astrophysics and Space Science》1981,77(1):131-158

Linearized nonradial expressions for light, colour and radial velocity changes are employed to examine the Baade-Wesselink method as applied to the problem of nonradial mode identification in variable stars. It is demonstrated that the usual assumption of a single-valued relation between surface brightness changes and colour variations fails for spherical harmonics withl>1. A Baade-Wesselink expression taking this into account is then given. Using test models for different variable star regimes it is shown that discrimination betweenl=0, 1, and 2 is currently feasible provided adequate attention is paid to pressure effects and to the procedure used to obtain radial velocity data. For higherl, mode discrimination, while possible in principle, is constrained by the stringent requirements on radial velocity measurements and by cases of confusion with lowerl. A review of related but less observationally demanding possible mode discriminators is given. This demonstrates that techniques based on amplitude and phase information in light and colour data may provide reliable discrimination betweenl=0, 1, and 2 when pressure effects are allowed for. For these techniques discrimination of higherl is limited by inadequate model atmosphere limbdarkening information and by confusion with lowerl.  相似文献   

Time structure of the extensive air shower front     

G. Agnetta  M. Ambrosio  C. Aramo  G. C. Barbarino  J. Beaman  B. Biondo  D. Campana  O. Catalano  L. Colesanti  G. D''Ali  A. Erlykin  F. Guarino  A. Lauro  J. Lloyd-Evans  A. Mangano  G. Osteria  A. A. Watson 《Astroparticle Physics》1997,6(3-4):301-312

The GREX/COVER_PLASTEX experiment has measured the temporal and spatial fine structure of the EAS disc at sea level in a new and original way, using resistive plate counter detectors for direct measurements of the arrival time of each particle crossing the detector. Data were taken at EAS core distances up to 100 m for shower size N > 10⁵ (PeV energy range). Arrival times of shower particles were measured with nanosecond accuracy. More than 450000 air shower events have been included in this analysis.  相似文献   

Auf dem Wege zur internationalen Seekarte     

Ltd. Reg. Dir. a. D. Hans Ermel 《Ocean Dynamics》1976,29(2):51-57

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