Date of Award:
Master of Science (MS)
Raymond L. Kerns
Near Logan, Utah, the Fish Haven Formation is a thick-bedded, dark-gray dolostone. The Laketown Formation, which rests on the Fish Haven, is a less resistant, medium-gray dolostone. The Ordovician-Silurian boundary has been placed locally at the top of the Fish Haven by stratigraphers, and in the lower Laketown Formation by paleontologists.
Four sections of the Fish Haven and Laketown dolostones were measured near Logan, Utah. The samples from these four sections were examined using petrography, insoluble residue analyses, x- ray diffraction, quantitative and qualitative x-ray fluorescence spectroscopy, and statistical analysis.
Petrography appears to be the best lab technique for distinguishing the two dolostones. This technique shows the grain size decreases in going from the Fish Haven Formation to the Laketown Formation. This decrease in grain size is also seen in the field.
All other laboratory techniques show that the two dolostones are very similar and cannot, in general, be distinguished. To summarize, the percent insoluble residue and the percent of quartz and illite found in each formation are independent of formational boundaries. X-ray diffraction, X-ray fluorescence spectroscopy, and statistical analysis all show that the two formations are geochemically similar.
A comparison of dolostones shows that they may, in general, be divided into two categories of pure and impure. The Fe2O3 content of pure dolostones may be less than the Fe2O3 content of impure dolostones. Other than the change in Fe2O3 content dolostones tend to be the same geochemically. This suggests that the process of dolomitization tends to obliterate any differences which may have originally existed and make all dolostones essentially uniform in composition.
Mecham, Brent H., "Petrography and Geochemistry of the Fish Haven Formation and Lower Part of the Laketown Formation, Bear River Range, Utah" (1973). All Graduate Theses and Dissertations. 3172.
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