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Powder X-ray diffraction analysis of homogeneous and heterogeneous sedimentary dolostones

Brian Jones, Robert W. Luth and Alexander J. MacNeil
Powder X-ray diffraction analysis of homogeneous and heterogeneous sedimentary dolostones
Journal of Sedimentary Research (September 2001) 71 (5): 790-799

Abstract

The %Ca (molar Ca/(Ca + Mg) X 100) in sedimentary dolomite, which ranges from 48 %Ca to 62.5 %Ca, can be determined by atomic absorption spectrometry, electron microprobe analysis, or powder X-ray diffraction analysis. The latter procedure, which relies on the fact that the position of the d (sub 104) reflection depends linearly on the Ca content, offers an easy and relatively inexpensive method of determining %Ca in dolomite. To date, such analyses have assumed that the dolostone is homogeneous with respect to the %Ca content of its constituent dolomite crystals. Herein, the XRD technique is extended to compositionally heterogeneous dolostones. A considerable amount of important information can be derived from X-ray diffractograms of dolostones if they are analyzed with peak-fitting techniques (PF-XRD). Specifically, this technique allows (1) determination of the %Ca with an accuracy of +0.5 %Ca, (2) identification of heterogeneous dolostone samples formed of more than one population of dolomite crystals as defined by their %Ca content, and (3) derivation of the proportion of each population of dolomite crystals with an accuracy of + 10%. The PF-XRD technique is a powerful analytical tool that provides valuable information on the major-element composition of low-Fe dolomite. Compared to other techniques, the PF-XRD technique is accurate, rapid, relatively inexpensive, and easy to use.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 71
Serial Issue: 5
Title: Powder X-ray diffraction analysis of homogeneous and heterogeneous sedimentary dolostones
Affiliation: University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada
Pages: 790-799
Published: 200109
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 38
Accession Number: 2002-000697
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200201
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