The geological distribution of mixed-layered kaolinite/expandables (K/E) and its importance within the kaolin group
- Illinois State Geological Survey, Champaign, IL (United States)
Kaolin-group minerals form in soils by at least three alteration pathways: (1) halloysite forms under pH and ionic extremes, and continues to increase in crystallinity and crystallite sizes along its alteration pathway; (2) mixed-layered kaolinite/smectite or kaolinite/expandables (K/S or K/E) forms from 2:1 layer silicates and contains true expandable layers and inherited Fe[sup VI] and Al[sup IV] within its 7[angstrom] layers. Minor increases in crystallinity and crystallite size accompany further alteration along the K/E pathway; and (3) well-crystallized kaolinites, dickites, and nacrites precipitate from solution, mostly in reducing environments where Fe[sup 2+] is removed from solution by crystallization of sulfides or carbonates. Kaolinite formed along pathways 1 and 2 retains attributes of parent material, whereas kaolinite from pathway 3 retains little. K/E occurs in Recent loessal soils of the Midwest and in related glacigenic paleosols, Quaternary-Pliocene paleosols, Eocene ball clays and their source paleosols on the Porters Creek Clay, Jurassic paleosols in Ireland, and Pennsylvanian underclays. The characteristic properties of K/E imprint kaolinite formed along this pathway. The frequency with which this imprint is being found suggests that K/E is spatially and chronologically more widespread than previously reported and that wider recognition of this imprint will increase the understanding of many kaolin occurrences.
- OSTI ID:
- 5011660
- Report Number(s):
- CONF-9303210-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:3; Conference: 27. annual Geological Society of America (GSA) North-Central Section meeting, Rolla, MO (United States), 29-30 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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