Publication Date

1982

Document Type

Dissertation/Thesis

First Advisor

Weiss, Malcolm P. (Malcolm Pickett), 1921-

Degree Name

M.S. (Master of Science)

Department

Department of Geology

LCSH

Geology, Stratigraphic--Eocene||Geology--Utah||Petrology--Utah

Abstract

The Green River Formation consists of green, gray, red, and variegated calcareous mudstones and claystones, thin- to medium-bedded siltstones and sandstones, channel sandstones and conglomerates, and thin-bedded carbonates. In general aspect the lower three-fourths is pale greenish-gray and the upper quarter buff colored. Sedimentary structures include cross-bedding, ripple marks, raindrop impressions, dessication cracks, burrows, rootlets, graded bedding, and concretions. Ostracodes, pelecypods, gastropods, reptile plates, fish scales and bones, algae, and charophytes comprise the fossil assemblage. Ostracodes, mollusks, and vertebrate remains are the most numerous and are locally conspicuous in outcrop. The Green River Formation sediments change facies from east to west across the plateau. Limestones become less abundant to the west. Locally dolomitized green calcareous mudstone interbedded with thin limestones and sparse siltstones indicate deposition in a lake-carbonate mudflat environment. Green, red, or variegated calcareous mudstone interbedded with thin-bedded siltstone and sandstone and channel sandstone and conglomerate indicate deposition in a f1uvia 1-deltaic setting. Cycles of green calcareous mudstone Cyclic repetitions of sediment sequences are common throughout the study area. The stratigraphic and geographic distributions of lithologic sequences are compatible with the model of an oscillating lake surface and resultant regression and transgression of near-shore lacustrine and proximal alluvial-deltaic-shoreline facies. The Green River Format ion represents a mixed fresh-water lake and alluvial environment. Its basin was filled, largely from the west, by material eroded from the Sevier Arch. As sediment loads varied and distributary systems migrated, the sediments of southwestern Lake Uinta alternated among fully lacustrine, transitional, and al1uvial-deltaic. The latter facies diminishes rapidly in thickness and volume to interbedded with thin-bedded sandstone ledges were deposited in shoreline (beach) settings. Cyclic repetitions of sediment sequences are common throughout the study area. The stratigraphic and geographic distributions of lithologic sequences are compatible with the model of an oscillating lake surface and resultant regression and transgression of near-shore lacustrine and proximal alluvial-deltaic-shoreline facies. The Green River Formation represents a mixed fresh-water lake and alluvial environment. Its basin was filled, largely from the west, by material eroded from the Sevier Arch. As sediment loads varied and distributary systems migrated, the sediments of southwestern Lake Uinta alternated among fully lacustrine, transitional, and al1uvial-deltaic. The latter facies diminishes rapidly in thickness and volume to the east.

Comments

Includes bibliographical references.||Includes illustrations and maps.

Extent

xii, 220 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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