33 Mineralogy/Crystallography, Petrology, and Geochemistry

Added due to amount of discipline submissions.

Tuesday, 10 March 2026
4:00 PM - 5:30 PM
RCC, 104

Why is the Ketona Dolomite an Extraordinary Geobotanical Habitat: Insights from Petrology, Pedology, and Geochemistry

Paper number: 33-2
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

The Ketona Dolomite is a relatively rare Middle Cambrian rock unit that crops out in Bibb County, AL along the banks of the Cahaba River. Certain localities of the outcrop form glade environments that host up to nine single site endemic plant species (vis Allison and Stevens, 2001). This research describes the geochemistry, petrology, and pedology of the Ketona Dolomite and associated soil parameters in order to identify unique factors that may contribute to the Ketona’s extraordinary ecological role. Thirteen samples of the dolomite and overlying soil were collected from glade localities. These were analyzed using petrographic facilities, XRD, pedological tools, and ICMS instrumentation at Auburn University. Thin sections analyzed by SEM and light microscopy provided basic microtextural information. Grain size ranged from 2.5 - 125 mm with the predominant grain size ranging from 10 - 25 mm. Samples showed predominantly planar, subhedral grain boundaries with varying degrees of fracturing and minor porosity infilled by occasional calcite and chalcedony. Porosity ranged from 0.07 – 3.3%. Mg/Ca ratios ranged from 0.55 – 0.62 and Sr/Ca ratios ranged from 0.28 – 0.52 (mmol/mol). Relative to each other, the 13 samples showed considerable variation in Al, V and Mn, with Al varying by more than an order of magnitude. NASC normalized REE patterns were relatively flat with several samples displaying Ce anomalies. Several samples show anomalously high concentrations of minor and trace elements. Soil analysis indicated a cationic predominance of Ca2+>Mg2+>K+>Na+. The low variation of bases content and P among horizons suggest limited influence of soil organic matter in the nutrient availability. The source of these elements could be attributed to the parent material. The soil organic content (SOC) varies between 0.2 and 1.9%. Together these preliminary analyses suggest that along with other ecological factors, the Ketona Dolomite may contribute to an environment favoring plant physiological specialization by excluding predominant flora.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411858

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