Authigenic Kaolinite and Dickite Associated with Metal Sulfides—Probable Indicators of a Regional Thermal Event

W. D. Keller
Geology Department, University of Missouri-Columbia Columbia, Missouri 65211
Note added in proof: A recent article entitled “Supercomputer Analysis of Sedimentary Basins” by C. M. Bethke, W. J. Harrison, Craig Upson, and S. P. Altaner, Science 239, 261–267 (1988) reported numerical experiments on a supercomputer that give insights on how temperatures of 60°–100°C may result from ground-water flow from the Illinois and Arkoma basins, driven by topographic relief on the Pascola arch and Ouchita Mountains. From these brines, ore minerals of Pb, Zn, Ba, and F were precipitated in the Mississippi Valley rocks, clay minerals of the 2:1 layer types were formed during diagenesis, and kaolin was deposited as late cement. Thus, from two clearly different perspectives—field observations of authigenic kaolin polytypes and laboratory supercomputer simulation—similar geologic conclusions were reached.

Abstract: Authigenic, well-crystallized kaolinite and dickite occur within sulfide mineral deposits (minesize to hand-specimen size occurrences) of the Mississippi Valley type in Arkansas, Kansas, Missouri, Iowa, Wisconsin, Illinois, and Indiana. Fluid inclusions in these rocks indicate temperatures of formation as high as 140°C. These authigenic kaolin-group minerals are probable geologic indicators of a regional thermal event. Such elevated temperatures are probably the result of heated waters derived from deeply buried sedimentary or tectonic basins, of passage of the region over a hot spot, or of an episode of thinning of the crustal plate in the mid-continent region.

Key Words: Dickite • Kaolinite • Metallic ores • Morphology • Regional thermal event

Clays and Clay Minerals; April 1988 v. 36; no. 2; p. 153-158; DOI: 10.1346/CCMN.1988.0360209
© 1988, The Clay Minerals Society
Clay Minerals Society (www.clays.org)