No abstract

No abstract

Diagenesis and metamorphism______________________________________ 18 Geologic setting _______________________________________________________________________ _ Chemical composition of sandstones_____________________________________ 20 Distribution and paleogeography _________________________________ _ Statistical methods___________________________________________________________ 20 Stratigraphic relations __________________________________________________ _ Means_________________________________________________________________________________ 20 Sampling plan __________________________________________________________________________ _ Geochemical relations______________________________________________________ 25 Methods of analysis ________________________________________________________________ _ 12 Analysis of variance________________________________________________ 25 Direct-reader spectrometric analyses, by Raymond

A set of four artificial glass reference standards, to which were added 46 trace elements, was designed at the U.S. Geological Survey for quality control of trace-element analysis in rocks. This study is a compilation of results from geochemical laboratories of many countries and from three laboratories of the Survey. These standards were made in 180-to 200pound lots by Corning Glass Works for the Survey. They were designed primarily for monitoring spectrochemical mobile laboratories, as well as for standardizing direct reading spectrometers, or for other similar uses, and are not for sale or distribution outside the U.S. Geological Survey. Medians, instead of the customary arithmetic means, are given for major and minor constituents and for 49 trace elements. Results expressed as medians, obtained by all methods of analyses for lead, rubidium, strontium, and uranium compare favorably with results given for isotopedilution analyses. Comparisons of quantitative with semiquantitative medians are made with the overall medians for 10 elements; the comparison shows the quantitative medians are in better agreement with the overall medians. The spread of the quantitative data for the three Survey laboratories are compared with each other as well as with the data from the outside laboratories; one Survey laboratory showed the least spread, whereas all the Survey laboratories showed a medium spread of results as compared with the larger spread of the outside laboratories. A quantitative spectrochemical study of compositional homogeneity is included as an important part of establishing the final accuracy of results on these standards. Some isotope-dilution data, for different bottles, are presented for lead and uranium as additional evidence for compositional homogeneity.

No abstract