Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Engineering Science

First Advisor

Brian F. Platt

Second Advisor

Jennifer N. Gifford

Third Advisor

Inoka H. Widanagamage

Relational Format



Bauxite is a heavily-mined aluminum ore that forms through the relative depletion of silica to aluminum. In North Mississippi, bauxite occurring within the Upper Midway and Lower Wilcox groups has been the subject of study for over a century. Despite the abundance and duration of research, controversy surrounds the subjects of bauxite genesis and economic value. The last detailed study of North Mississippi bauxite was in the 1980’s, so the goal of this project is to apply newly available technologies and modern hypotheses on bauxite formation to refine and obtain new data. Fieldwork observations yielded pisoliths, horizonation, and possible rhizoliths, which support a lateritic genesis at the most well exposed outcrop, which is located in Pontotoc County and mapped as the Upper Midway Group. Additionally, stratigraphic trends in percentages of SiO2, Al2O3, and Fe2O3 at this location closely resembled that of a typical lateritic bauxite profile reflecting the depletion of SiO2 and enrichment of Fe2O3 upsection. Abundances of chromium (Cr) and nickel (Ni) as well as percentages of zirconium (Zr), gallium (Ga), and chromium (nickel) (Cr(Ni)) determined the bauxite protolith was acidic and/or sedimentary and that bauxites were of the high-iron lateritic variety. This aligned with the occurrence of siderite (iron carbonate) in the interpreted protolith as well as ratios of lanthanum to yttrium that indicated an acidic paleoenvironment throughout the section. Lastly, stable isotope data confirmed prior hypotheses of a warm paleoclimate and indicated subaerial exposure of the interpreted parent material. A comparison with the reworked bauxite of the Lower Wilcox Group found that pisoliths were different in regards to structure and chemistry, supporting the hypothesis that these originated in a separate event or under different conditions.

Included in

Geology Commons



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