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An occurrence of lacustrine Mg-smectite in a pan of the southwestern Kalahari, Namibia

Published online by Cambridge University Press:  09 July 2018

F. Mees
F. Mees*
Affiliation:
Department of Geology and Soil Science, University of Ghent, Krijgslaan 281 S8, B-9000 Ghent, Belgium
*
*E-mail: florias.mees@rug.ac.be
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Abstract

The clay fraction of the deposits of the Otjomongwa Pan, southwestern Kalahari, is dominated by Mg-smectite. This mineral formed as an authigenic precipitate in a groundwater-fed lake, without involving the transformation of a precursor mineral. During the earliest recorded period, Mg-smectite formed together with sepiolite and dolomite in a shallow lake. This period was ended by a change in environmental conditions that led to an increase in the depth of the lake and a decrease in salinity and Mg content of the water. This resulted in a transition to a mineral association without sepiolite and including calcite, together with Mg-smectite and dolomite. The depth of the lake gradually decreased after this event, while the lake water progressively became depleted in Mg.

Keywords

smectitesepiolitedolomitelacustrine sedimentationKalahari DesertNamibia
Type
Research Article
Information
Clay Minerals , Volume 36 , Issue 4 , December 2001 , pp. 547 - 556
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2001

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