ANALYZING CHEMICAL VARIABILITY AND ITS RELATIONSHIP TO ENGINEERING PROPERTIES IN THE BURLINGTON-KEOKUK FORMATION, SPRINGFIELD, MISSOURI

The Burlington-Keokuk formation is regionally extensive through Iowa and Missouri and can be roughly-correlated into Arkansas and Oklahoma. This formation is the surficial rock unit in most of the Springfield plateau. It has been studied extensively in Northeast Missouri, Iowa, and Illinois. These studies looked at the lateral variability of depositional facies with only a few geochemical studies. In southwest Missouri there are a limited number of geochemical studies.

In the Springfield Plateau, many caves, sinkholes, and other karst features exist which appear to relate to the hydrology within the Burlington-Keokuk and adjacent units. This relation may be caused by the amount of chert variability or lithological changes both vertically and horizontally, going from a purely crystalline limestone with an occasional bivalve fossil to a crinoidal packstone. Another change is seen in surface streams, where beds of Burlington-Keokuk appear to serve as aquicludes at certain points in the stream, suggesting vertical variability alongside horizontal change. Anecdotally, local quarry operators suggest that LA Abrasion tests indicate vertical variations, and data from LA Abrasion confirms their suggestion, offering possible support for chemical differences seen in Fe, Sr, Co, and U. Data from ICP-MS chemistry methods (to investigate chemical variability), and LA Abrasion testing (to investigate variations in the formation's abrasiveness) are being used to evaluate vertical variation in the formation. Comparing the chemical differences to abrasiveness could help explain trends seen on the surface and give a reason to differences seen in LA Abrasion tests.