Elemental abundance, classification

In Chapter 1 and again above, we introduced the cosmochemical classification of elements based on their relative volatilities in a system of cosmic (solar) composition. In a cooling solar gas, elements condense in a certain order, depending on their volatility (Table 7.1). Condensation and evaporation partition elements between coexisting gas and solid (or liquid) phases, and the removal of one or the other of these phases can fractionate element abundances of the system as a whole from their original cosmic relative proportions. 

Patterns of Elemental Distribution. The major, minor, and trace element abundances and the lithology of the stratigraphic sequence are summarized in Tables I and II for the Beulah coals. The data from the Center Mine is given in Karner and others ( 1) where the spatial distribution of elements in the seam was described as fitting into several patterns. In this study the classification of elemental distribution patterns includes 1) Concentration at... 

FIGURE 8 Plot of K20 versus Si02 for various models of bulk continental crustal composition, superimposed on the classification of calc-alkaline volcanic rocks. The model favored here is shown in the heavy black circle. A variety of other compositions have been proposed on the basis of plate tectonic models (e.g., andesite, ocean island basalt open crosses) and various seismic and geological models (open squares). These various models predict a wide range of heat-producing element abundances (K, Th, U) and thus can be tested from heat-flow data. 

Table 1. Classification of chemical elements according to their water solubility, natural abundance and toxicity.

Schematic depth ocean profiles for elements. This figure is based on a classification of elements according to their oceanic profiles given by Whitfield and Turner (1987). Uptake of some of the elements, especially the recycled ones, occurs somewhat analogously as that of nutrients. There are some elements such as Cd that are non-essential but may be taken up (perhaps because they mimick essential elements) the same way as nutrients. The concentration ranges given show significant overlap, since the concentrations of the elements also depend on crustal abundance.

Isotopic abundances are listed either as their sum being 100 % or with the abundance of the most abundant isotope normalized to 100 %. The latter is used throughout this book because this is consistent with the custom of reporting mass spectra normalized to the base peak (Chap. 1). The isotopic classifications and isotopic compositions of some common elements are listed below (Table 3.1). A full table of the elements is included in the Appendix. 

In the MK system, most J-type stars are classified as C4-5 4-5 stars which show very strong C and CN bands. Yamashita(l972,l975) classified many C7-9 stars most of which are CS or SC stars. His classification of C7-9J stars is mainly based on Cl2Cl3(0,l)band at 6168 A, C13N(4,0)band at 6260 A, and Lil 6708 A line. In most of C7-9 stars, lines of s-process elements are greatly enhanced. It is a question if in all J-type stars abundances of s-process elements are nearly normal or not. 

The classification of chemical elements into major and minor or trace element categories is somewhat arbitrary. Thermodynamically, a minor element may be defined as one that is partitioned between coexisting phases in compliance with laws of dilute solutions, such as Henry s law, eq. (7.2b). In geochemical parlance, however, trace elements are usually categorized on the basis of abundance data. In this context, the mineral, rock or environment containing the chemical elements must be defined as well as the concentration boundary separating a major and trace element. 

Undifferentiated and differentiated meteorites. 03.1.3.2 Cosmochemical classification of elements Cl Chondrites as Standard for Solar Abundances... 

Figure 1 Element/Si mass ratios of characteristic elements in the major groups of chondritic (undifferentiated) meteorites. Meteorite groups are arranged according to decreasing oxygen content. The best match between solar abundances and meteoritic abundances is with Cl-meteorites. For classification of meteorites,...

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.)... 

Figure 17.2 shows the relative abundance of the elements of the universe and of the earth. The abundances are approximate, as a consequence of die difficulties in their assessment and limitations of experimental techniques. The abundances in the universe (based on spectral measurements on stars and interstellar matter) are used as a refinement of data obtained for the solar system. Stellar light is divided in spectral classes depending on the surface temperature of the star, see Fig. 17.1. The various classes (Harvard Spectral Classification) show lines of the elements as listed below in approximately decreasing intensity ...

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