Date of Award:
5-1973
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Geosciences
Department name when degree awarded
Geology
Committee Chair(s)
Raymond L. Kerns, Jr.
Committee
Raymond L. Kerns, Jr.
Committee
Donald R. Olsen
Committee
Robert Q. Oaks, Jr.
Abstract
Mineralogical and petrographic analyses of the upper Jurassic - lower Cretaceous units in the vicinity of the Dinosaur National Monument quarry near Jensen, Utah, have elucidated their characteristics and the locations of formational boundaries. The lower part of the Morrison Formation is distinguished by a decreased amount of illite and an increased amount of kaolinite. In contrast, the underlying Curtis Formation contains an approximately equal mixture of illite and kaolinite. The lower Salt Wash Member and the upper Brushy Basin Member of the Morrison are both lithologically and mineralogically identifiable in this area. Above the boundary between the two, kaolinite decreases and illite increases. The strata above the Morrison, here recognized as an extension of the Cedar Mountain Formation, reveal another change in clay content. They contain kaolinite as the dominant clay mineral, whereas illite is almost completely absent.
The upper Curtis Formation is a near-shore marine deposit, whereas the members of the Morrison Formation are fluvial and lacustrine. A possible climatic or depositional change is equated with the changes in the clay content within the members of the Morrison Formation. After deposition of the Morrison, the lower Cretaceous sediments that now comprise the Cedar Mountain Formation accumulated. These formed in a transitional zone (fluvial to littoral) and were eventually covered by the Dakota Formation (littoral) and the Mowry Formation (marine).
Checksum
b48f854e093bb23f7a44500ee1cc949b
Recommended Citation
Bilbey, Sue Ann, "Petrology and Geochemistry of the Morrison Formation, Dinosaur Quarry Quadrangle, Utah" (1973). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 1641.
https://digitalcommons.usu.edu/etd/1641
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