Master's Theses

Date of Award

Spring 1975

Degree Name

Master of Science (MS)

Department

Geosciences

Advisor

Michael E. Nelson

Abstract

The Shafer Limestone is the upper-most member of the Wolfcampian Elephant Canyon Formation in east-central Utah. The unit is exposed at the Shafer Trail area and forms a marine carbonate tongue that thins eastward. The unit is conformable with underlying and overlying units but displays fairly sharp contacts. Fossils, oolites, pellets and terrigenous particles form the grains in the Shafer Limestone. The unit consists of light-gray to brownish limestone comprising mainly fossil grains at the Goose Neck, Dead Horse Point and Pyramid Butte areas to the west and terrigenous grains at the Potash area to the east. Brachiopods, crinoids, gastropods, and pelecypods are principal components of the fauna. Mineral composition includes calcite, dolomite, opaques, clay minerals, and ferromagnesian minerals in order of decreasing importance. Microspar and micrite, with minor amounts of spar, form the matrix and cement and both grain and non- grain supported fabric are present. The unit was deposited under a variety of shallow marine conditions when an arm of the sea transgressed from the Oquirrh Basin, which lay to the northwest of the area and reached as far southeast as the Potash area. The strata on the west side of the Shafer Trail area were deposited mainly in quiet subtidal environments, but deposition above the wave base, probably in a near-shore environment, is suggested for the eastern strata. Ecological conditions of the Shafer Sea as suggested by paleontological and sedimentological criteria indicate that clear, warm, shallow, normal marine conditions prevailed. These data suggest good circulation with moderate to high hydrodynamic energy. Abundant burrowing organisms, mainly gastropods and pelecypods, suggest that the bottom was soft.

Rights

Copyright 1975 Ali Seyrafian

Comments

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