The influence of analytical error upon the interpretation of chemical variations in clay minerals

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Authors:Warren, E. A.; Ransom, B.
Author Affiliations:Primary:
CNRS, Cent. Geochim. Surface, Strasbourg, France
Univ. Calif. at Berkeley, United States
Volume Title:Clay Minerals
Source:Clay Minerals, 27(2), p.193-209. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1992
Note:In English. 49 refs.; 2 tables, charts
Summary:Understanding the chemical variability of clay minerals depends on the analytical reliability of the techniques used. Uncertainties in clay mineral compositions were computed for common sources of analytical error such as those that arise from contaminant phases present in clay size-fractions in concentrations below the detection limit of routine XRD screening techniques, and the analytical limits of precision for TEM/AEM analysis. When plotted on standard diagrams used to represent clay mineral compositions, the calculated error envelopes were found to be of significant size, such that analyses of pure illites and pure smectites straddled the field for mixed-layered illite-smectites. In addition, on some diagrams random analytical errors resulted in linear trends identical to those caused by mixtures of two or more clay minerals. It follows that variations in the compositions of clay minerals reported in the literaure do not always necessarily represent the actual chemical variation of the minerals. As a result, current interpretations of clay compositional variations may not be as definitive as hoped.
Subjects:Chemical analysis; Chemical properties; Clay mineralogy; Clay minerals; Errors; Experimental studies; Interpretation; Minerals; Sheet silicates; Silicates; TEM data; X-ray diffraction data
Abstract Numbers:93M/1353
Record ID:1992037804
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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