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Asymmetric zonation of a thick Ordovician K-bentonite bed at Kinnekulle, Sweden

Ann Marie Brusewitz
Asymmetric zonation of a thick Ordovician K-bentonite bed at Kinnekulle, Sweden
Clays and Clay Minerals (August 1988) 36 (4): 349-353

Abstract

The clay fraction of a approximately 2-m-thick K-bentonite at Kinnekulle in southwestern Sweden has been studied by X-ray powder diffraction, chemical analyses, and cation-exchange capacity determinations. Previous investigations of the upper half of this bed (B-bed) have shown the clay mineral to be illite/smectite (I/S), containing about 50% illite layers at the center of the bed and 65% illite layers at the upper contact. New data on six samples from the lower part of the bed show no zonation, the I/S containing about 50% illite layers in all samples. The bentonite occurs in limestones and shales overlying a 40-m-thick limestone bed and is overlain by limestones, marls, and shales ( approximately 90 m), which in turn are overlain by a 40-m-thick diabase. The limestones are silicified in contact with the bentonite, particularly beneath the B-bed. The increased K content towards the upper contact may therefore have resulted from diffusion of K-bearing solutions from overlying shales, a process that was impeded in the lower part of the bed, probably by the silicification.


ISSN: 0009-8604
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 36
Serial Issue: 4
Title: Asymmetric zonation of a thick Ordovician K-bentonite bed at Kinnekulle, Sweden
Affiliation: Geol. Surv. Swed., Uppsala, Sweden
Pages: 349-353
Published: 198808
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 22
Accession Number: 1988-072659
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N55°15'00" - N69°15'00", E11°00'00" - E24°15'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 1988
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