STABLE ISOTOPE AND CRYSTALLINITY VARIATIONS IN KAOLIN DEPOSITS OF GEORGIA IN UP DIP TO DOWN DIP OCCURRENCES

Kaolin mining is a one billion dollar industry for the state of Georgia and is used primarily in paper coating, but is also used in plastics, ceramics, paints, and pharmaceuticals. Recently, kaolin has been used in the production of nano-composites showing its versatility and economic importance. Economically exploited kaolin beds south of the Fall Line are formed by weathering of aluminosilicate minerals, with the source being aluminosilicate-rich granitic rocks in the Georgia Piedmont region. Variations in the crystal structure and chemical state are vital to how the clays will be used in the production industry. This study examined the δ¹⁸O and δD isotopic variation in sediment-hosted kaolin deposits geologically located in up-dip to down-dip occurrences in the Eocene-aged Huber Formation of central Georgia. When isotopic values were compared with that of mineralogy determined by X-ray diffraction, there were no correlations with kaolinite crystalline defect disorder. However, the isotopic values showed correlations with location and a general trend of δD enrichment in the up-dip direction. This supports the notion that kaolin beds in the up-dip direction (with less overburden) have experienced recrystallization with meteoric waters at a higher temperature.