41-14 SEDIMENTOLOGICAL ANALYSIS AND DEPOSITIONAL INTERPRETATION OF BURLINGTON-KEOKUK LIMESTONE STRATA, SOUTHEAST CALLAWAY COUNTY, MISSOURI

Session: Paleontology, Stratigraphy, Sediments, and Soils (Posters)

Presenting Author:

Authors:

Abstract:

A roadcut along County Road 419 in southeast Callaway County contains Mississippian strata (Burlington-Keokuk Limestone) in which little is known about this exposure. This study uses petrography for sedimentological analysis and depositional interpretation of three medium-bedded strata within the Mississippian sequence. The three strata are designated as A (lower), B (middle), and C (upper). Stratum A contains horizontal and vertical variation of grains that includes carbonate ooids (some replaced with quartz), quartz grains, and a fine-grained microcrystalline calcite-clay matrix. Vertical change in stratum A may indicate a shift from near-shore (ooids) in the bottom portion to deeper shallow marine (muddy carbonate matrix) conditions in the upper portion. Stratum B is similar to A, however, there is more horizontal consistency of sediments in Stratum B. Vertically, there is a change from ooids near the bottom portion to more fine-grained microcrystalline calcite-clay matrix and microcrystalline chert near the top. Thus, stratum B may also indicate a shift from near-shore to deeper shallow marine conditions like stratum A. Stratum C exhibits the least amount of horizontal and vertical variation among grains and is predominantly a mixed fine-grained sparry calcite-clay matrix, lacking ooids. This may suggest environmental conditions did not change much throughout the entire deposition of stratum C. Collectively, thin sections of strata A, B, and C suggest fluctuating near-shore to shallow marine conditions throughout the Mississippian strata and later authigenic silicification. Furthermore, due to the presence of oolites, this exposed section is thought to be the Keokuk Formation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

doi: 10.1130/abs/2026SE-13854

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