Mineralogy, Crystallinity, O18/O16, and D/H of Georgia Kaolins

Ali Asghar Hassanipak1 and Eric Eslinger2
School of Geophysical Sciences, Georgia Institute of Technology Atlanta, Georgia 30332
Department of Geology, West Georgia College Carrollton, Georgia 30117
1 Present address: Department of Mining Engineering, University of Tehran, Tehran, Iran.
2 Present address: Cities Service Oil and Gas Corporation, Technology Center, Box 3908, Tulsa, Oklahoma 74102.

Abstract: Mineralogy, kaolin crystallinity, Fe content, δO18, and δD were determined for late Cretaceous “soft” and early Tertiary “hard” Georgia kaolins. The crystallinity of the <0.5-, 0.5–1.0-, and 1.0–2.0- µm size fractions of soft kaolins was higher than that of equivalent size fractions of hard kaolins. δO18 and δD of the soft and hard kaolins ranged between 18.5 to 23.1‰, and −64 to −41‰, respectively, and could not be used to discriminate soft from hard kaolins. The trends of crystallinity vs. δO18 were different for kaolins collected at different localities, and, for a given sample, δO18 generally decreased with increasing crystallinity and with increasing crystallite size. These data indicate that the Tertiary kaolins could not have been simply derived from the Cretaceous kaolins by winnowing unless post-sedimentation recrystallization of one or both occurred. δD vs. δO18 systematics indicate that the late Cretaceous to early Tertiary Georgia kaolins crystallized over a temperature range of about 15°C in the presence of waters that varied little in isotopic composition.

Key Words: Crystallinity • Hardness • Isotope • Kaolin • Origin • Oxygen isotopes

Clays and Clay Minerals; April 1985 v. 33; no. 2; p. 99-106; DOI: 10.1346/CCMN.1985.0330203
© 1985, The Clay Minerals Society
Clay Minerals Society (www.clays.org)