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  • Articles  (6)
  • geochemistry  (6)
  • Springer  (6)
  • 2005-2009
  • 1980-1984  (6)
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  • Geosciences  (6)
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  • Articles  (6)
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  • Springer  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 14 (1982), S. 331-342 
    ISSN: 1573-8868
    Keywords: Correspondence analysis ; extendedQ-mode factor analysis ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract When factor analysis is used in geochemistry, it may be useful for factors to be transformed by rotations in order to be identified either to the end members of a mixing model (Miesch, 1976a),or to known chemical equilibriums. It requires that the formula for recomputing data from the factors may be written in a factored manner, which is generally not the case in correspondence analysis. The present paper shows that this becomes possible with data having constant row sums. As an example, the method is tested on the lavas of Paricutin Volcano, already examined by using an extended Q-mode factor analysis (Miesch, 1979).Recomputation of the data after projection gives simular results for both methods. Otherwise, the fact that correspondence analysis provides centered factors makes it well suited to the study of chemical reactions leading to constant mass transformations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-8868
    Keywords: autocorrelation ; cross correlation ; geochemistry ; spectral analysis ; tectonic structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Time series analysis (autocorrelation, cross correlation, spectral analysis)is used to reconstruct tectonic structures from geochemical drill hole log data. After segmentation of a log one obtains typical patterns of significant correlations by cross correlation analysis. These patterns can be included in a “log-segment-correlation matrix” (LSCM)and are interpreted as repetitions caused by fractures or as folds extending over one or more segments. Smaller tectonic structures can be detected by spectral analysis. Examples are given from Pb-Zn exploration drill holes in the Paleozoic of Graz (Austria).
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 16 (1984), S. 531-564 
    ISSN: 1573-8868
    Keywords: Closure ; closed number system ; logistic ; logratio ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The analysis and interpretation of compositional data, such as major oxide compositions of rocks, has been traditionally plagued by the so-called constant-sum or closure problem. Particular difficulties have been the lack of a satisfactory, interpretable covariance structure and of rich, tractable, parametric classes of distributions on the simplex sample space. Consideration of logistic and logratio transformations between the simplex and Euclidan space has allowed the introduction of new concepts of covariance structure and of classes of logistic-normal distributions which have now opened up a substantial and meaningful array of statistical methodology for compositional data. From the motivation of a wide variety of practical geological problems we examine the range of possibilities with this new approach to the constant-sum problem.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 13 (1981), S. 93-117 
    ISSN: 1573-8868
    Keywords: multivariate analysis ; sediment texture ; geochemistry ; Eastern Gulf margin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Several multivariate statistical analyses were performed upon sediment textural and chemical data derived from a four-year study of the surface sediments of the Eastern Gulf of Mexico continental margin. The results were compared with the surface sediment facies map and the generalized dynamical patterns deduced by Doyle and Sparks (1980) using traditional sediment textural and compositional parameters and single moment method statistics. The addition of multivariate techniques suggested relationships among variables which were subtle and not otherwise readily apparent. Mapping of Q-mode clusters based upon sediment texture alone showed a patchy distribution of sediment classes within the traditional descriptive facies. A seasonal variation in sediment texture at several stations was also revealed which we have attributed to the reworking of the bottom and sediment transport by hurricanes and winter frontal storm systems which sweep across the shallow shelf. Based upon first-order trend surface analysis over Q-mode ordination and stepwise linear regression analysis we have interpreted that total organic carbon content, not the amount of fine grained sediment present nor the clay mineralogy, is the most important parameter affecting the distribution of the trace metals Ba, Cr, Cu, Fe, Pb, and Zn. These relationships suggest to us that organic complexing with trace metals is important in the Eastern Gulf margin sediments. Finally a strong relationship between the group of trace metals Ba, Pb, Zn, Cd, and CaCO3 shown by these analyses may be the result of biological uptake in the deeper portions of the study area and/or incorporation into the CaCO3 crystal lattice by limited substitution for calcium.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 16 (1984), S. 217-236 
    ISSN: 1573-8868
    Keywords: nonlinear regression ; discriminant analysis ; decomposition of mixtures ; pattern recognition ; geochemistry ; sedimentology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The decomposition problem—the assignment of sample observations to component populations—is studied in a spatial context. The observations are spatially located and the assignment to component populations takes into account the value of each observation as well as the values of neighboring observations. Both parameter estimation and assignment rules use a new method that integrates a standard multivariate decomposition algorithm with nonlinear regression. The method is illustrated and tested with artificial data. The distribution of the trace component Cr2O3 in recent Lake Michigan sediments is, then, analyzed by the method. It yields a pattern of component populations that is correlated with the Lake's bottom structure and depositional environments.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 16 (1984), S. 617-635 
    ISSN: 1573-8868
    Keywords: principal-component analysis ; subcomposition ; geochemistry ; closed arrays ; compositional data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The high-dimensionality of many compositional data sets has caused geologists to look for insights into the observed patterns of variability through two dimension-reducing procedures: (i)the selection of a few subcompositions for particular study, and (ii)principal component analysis. After a brief critical review of the unsatisfactory state of current statistical methodology for these two procedures, this paper takes as a starting point for the resolution of persisting difficulties a recent approach to principal component analysis through a new definition of the covariance structure of a composition. This approach is first applied for expository purposes to a small illustrative compositional data set and then to a number of larger published geochemical data sets. The new approach then leads naturally to a method of measuring the extent to which a subcomposition retains the pattern of variability of the whole composition and so provides a criterion for the selection of suitable subcompositions. Such a selection process is illustrated by application to geochemical data sets.
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