Geochemical distribution of the elements

Goldschmidt, in 1932, classified the elements into groups based initially on their distribution among the mineral phases in meteorites, as follows  

Siderophile elements, tending to occur as metals and alloys (e.g., 

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In the final section, the overall geochemical distribution of the elements is considered in the light of electronic structure theories. Previous attempts to classify elements on the basis of their preferences for compound formation with oxygen or sulfur are reviewed. 

Goldschmidt V. M. (1923). Geochemical laws of the distribution of the elements. Videnskaps. Skrift Mat.-Natl Kl, 3 1-17. 

Chapter 5 summarizes the crystal field spectra of transition metal ions in common rock-forming minerals and important structure-types that may occur in the Earth s interior. Peak positions and crystal field parameters for the cations in several mineral groups are tabulated. The spectra of ferromagnesian silicates are described in detail and correlated with the symmetries and distortions of the Fe2+ coordination environments in the crystal structures. Estimates are made of the CFSE s provided by each coordination site accommodating the Fe2+ ions. Crystal field splitting parameters and stabilization energies for each of the transition metal ions, which are derived from visible to near-infrared spectra of oxides and silicates, are also tabulated. The CFSE data are used in later chapters to explain the crystal chemistry, thermodynamic properties and geochemical distributions of the first-series transition elements. 

The ionic radius criterion for interpreting geochemical distributions of trace elements was given a boost in the early 1970 s when correlations were shown to exist between ionic radii and partition coefficients of some trace elements (Onuma et al., 1968 Higuchi and Nagasawa, 1969 Jensen, 1973). The influence of cation radius and charge on trace element distribution patterns was demonstrated by measurements of the distribution coefficient, >, defined by... 

In this, the last major chapter of the book, we turn our attention to the applications of modern electronic structure models and eoncepts to more general geochemical problems namely, those described by Goldschmidt as being eoncerned with the distribution of elements in the geochemical spheres and the laws governing the distribution of the elements (see Preface). 

Table 8.10. Geochemical classification" of the elements, according to distribution between iron, sulfides, silicates, atmosphere, and organisms... 

A relationship can be demonstrated between the distribution observed in the seam and the geochemical properties of the elements. The relationship is summarized in Table V. At present the information in Table V is based only on the study reported here, and therefore must be considered to be a qualitative presentation of rules of thumb. Current work in our laboratory is focused on several additional lithologic sequences. As more data is accumulated we expect to be able to extend Table V and incorporate quantitative relationships. ... 

FIGURE 1-9 Geochemical Classification of the Elements. (Adapted with permission from P. A. Cox, The Elements, Their Origin, Abundance, and Distribution, Oxford University Press, Oxford, 1990, p. 13.)... 

To this point, we have emphasized that the cycle of mobilization, transport, and redeposition involves changes in the physical state and chemical form of the elements, and that the ultimate distribution of an element among different chemical species can be described by thermochemical equilibrium data. Equilibrium calculations describe the potential for change between two end states, and only in certain cases can they provide information about rates (Hoffman, 1981). In analyzing and modeling a geochemical system, a decision must be made as to whether an equilibrium or non-equilibrium model is appropriate. The choice depends on the time scales involved, and specifically on the ratio of the rate of the relevant chemical transition to the rate of the dominant physical process within the physical-chemical system. 

Goldschmidt VM (1929) The Distribution of the Chemical Elements. Proceedings of the Royal Institution of Great Britain 26 73-86, as quoted in Mason B, Victor Moritz Goldschmidt Father of Modern Geochemistry, The Geochemical Society San Antonio TX184 pp. 

Figure 1.14 Curve showing the typical distribution of the geochemically abundant elements.

ABSTRACT Southwest China s geochemical mapping project to measure 76 elements was initiated in 2000. 2700 composite samples were analysed by ICP-MS, XRF and ICP-AES, along with other techniques where necessary. The resulting geochemical maps shows the distribution of majority of the elements in the periodic table. 

The 76 elements geochemical maps show the distribution of all elements in the periodic table, especial for rare and dispersive and precious metals elements. 

Trace elements are useful tracers of geochemical processes mostly because they are dilute their behavior depends primarily on the trace element-matrix interaction (e.g., Rb-host feldspar, Sr-calcite) and very little on the trace-trace interaction (e.g., Rb-Rb, Sr-Sr). Consequently, the distribution of trace elements among natural phases largely obeys the linear Henry s law. The modeling of trace elements in various geological environments (magmas, hydrothermal fluids, seawater,...) relies on three different aspects... 

The Koongarra U deposit in the Northern Territory of Australia has been studied to evaluate the processes and mechanisms involved in the geochemical alteration of the primary ore zone, and to model the formation of the secondary U ore zone and dispersion fan (Duerden 1991 Duerden Airey 1994). Studies of the distribution of the U in the dispersion fan (Murakami et al. 1991) have provided data on the fixation of U leached from the primary ore deposit. Their work has shown that, for this system, fractures are not only preferential pathways for ground-water movement but also contain secondary minerals with high sorption capacity for elements such as U. Even in the monsoonal climate, in which this deposit is located, a significant proportion of the uranium has not been released from the vicinity of the primary ore body. 

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