Depositional history of the Porters Creek Clay of the upper Mississippi Embayment using chemical, stratigraphic and trace-fossil data

Author

Joseph Calvin Faulkerson

Date of Award

12-1989

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Otto C. Kopp

Committee Members

Richard W. Arnseth, Steven G. Driese

Abstract

The depositional history of the Porters Creek Clay (Paleocene) was determined using stratigraphic, trace-fossil, mineralogic, and chemical data. This approach made it possible to examine the relationship between the chemical and stratigraphic data and to determine whether it is possible to use a chemical-stratigraphic approach to the analysis of shale basins. Samples were collected from three active clay pits located at Bloomfield, Missouri; Olmsted, Illinois; and Paris, Tennessee. All three locations are part of the Upper Mississippi Embayment. Samples were collected at about 1.5 meter intervals. Chemical data were obtained from X-ray fluoresence (XRF) analysis. Data were reported as percent oxides of sodium, magnesium, aluminum, silicon, phosphorus, potassium, calcium, titanium, manganese, and iron. Elements reported include sulfur, chromium, barium, rubidium, strontium and zirconium. The concentrations of the various chemical species were ploted versus depth in the pits and compared to the measured sections from each pit. Trace-fossil data were used to gain some insight into the oxygenation conditions at the time of deposition that would effect the kinds of authigenic minerals that might occur. The mineral species present were constrained by petrographic and X-ray diffraction techniques. The dominant minerals include quartz, siderite, goethite, chalcedony, glauconite, muscovite, kaolinite, illite, feldspar, pyrite, gypsum, and smectite. The data indicate that the Bloomfield, Missouri and the Olmsted, Illinois deposits were deposited in similar environments. This is most evident in the plots of S, P₂O₅, SiO₂, and Al₂O₃. At Bloomfield and Olmsted these chemical species behave in a similar fashion. In the plots of chemical variables versus depth, S and P₂O₅ tend to define a distinctive sedimentary package in the lower part of each pit and are considered to be related to the observed organics and pyrite that are prominent in the lower portion of the Bloomfield and Olmsted pits. Fe₂O₃ does not correlate well with sulfur due to the influence of detrital iron minerals throughout the section. High CaO concentrations (over 7 percent) at the base of the Bloomfield section correlate with the occurrence of the only foraminifera in the section. SiO₂ and Al₂O₃ are important constituents in the upper portion of the Bloomfield and Olmsted pits. An inverse relationship exist between the concentrations of SiO₂ and Al₂O₃. SiO₂ dilutes AI₂O₃ as a result of higher silt concentrations in the upper part of both sections. The occurrence of pyrite, glauconite and siderite are compared to the environmental criteria described by Berner (1981) and Maynard (1982), and indicate that the depositional environment of the Porters Creek Clay ranged from anoxic sulfidic to non-sulfidic post oxic. Previous workers have interpreted that the deposition of the Porters Creek Clay as representing part of a transgressive-regressive sequence. The data from this research are in agreement with these conclusions. It was possible to define a transgressive and regressive facies in the Porters Creek based on the chemical-stratigraphic data, but it is important to note that the chemical data are sensitive to late events such as the intrusion of clastic dike seen at the Paris location. The inverse relationship between SiO₂ and Al₂O₃ seen at Bloomfield and Olmsted was also observed in the Paris data, but the relationships of other chemical species at Paris to the stratigraphy were not always clear. The differences between Bloomfield, Olmsted and Paris are thought to be due in part to the Paris clastic dike event and to the relative positions of the sections within the depositional basin. Whereas Bloomfield and Olmsted are very near the axis of the basin, Paris is located well off the axis of the basin. Principal Component Analysis (PCA) of the chemical data also indicated a fundamental difference at the Paris location.

Recommended Citation

Faulkerson, Joseph Calvin, "Depositional history of the Porters Creek Clay of the upper Mississippi Embayment using chemical, stratigraphic and trace-fossil data. " Master's Thesis, University of Tennessee, 1989.
https://trace.tennessee.edu/utk_gradthes/12939