Illite polytype quantification using Wildfire© calculated x-ray diffraction patterns

Clays and Clay Minerals
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Abstract

Illite polytype quantification allows the differentiation of diagenetic and detrital illite components. In Paleozoic shales from the Illinois Basin, we observe 3 polytypes: 1Md, 1M and 2M1. 1Md and 1M are of diagenetic origin and 2M1 is of detrital origin. In this paper, we compare experimental X-ray diffraction (XRD) traces with traces calculated using WILDFIRE© and quantify mixtures of all 3 polytypes, adjusting the effects of preferred orientation and overlapping peaks. The broad intensity (“illite hump”) around the illite 003, which is very common in illite from shales, is caused by the presence of 1Md illite and mixing of illite polytypes and is not an artifact of sample preparation or other impurities in the sample. Illite polytype quantification provides a tool to extrapolate the K/Ar age and chemistry of the detrital and diagenetic end-members by analysis of different size fractions containing different proportions of diagenetic and detrital illite polytypes.

Publication type Article
Publication Subtype Journal Article
Title Illite polytype quantification using Wildfire© calculated x-ray diffraction patterns
Series title Clays and Clay Minerals
DOI 10.1346/CCMN.1996.0440615
Volume 44
Issue 6
Year Published 1996
Language English
Publisher The Clay Minerals Society
Description 8 p.
First page 835
Last page 842
Online Only (Y/N) N
Additional Online Files (Y/N) N
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