Abstract

Siliceous shales of the Laney Member of the Green River Formation are exposed in outcrops around Fontenelle Reservoir in the northwest corner of the Green River Basin, Wyoming. An analysis of these shales is important to an understanding of the origin of laminites in the Green River formation. The shales are rhythmic, varve -like laminites, composed of quartz, authigenic potassium feldspar , dolomite, and zeolite minerals. The association of these minerals suggest that the original sediment contained significant amounts of volcanic ash, and were deposited in a shallow, near-shore, oxygenated saline - alkaline lake environment, as inferred from (1) the association of stromatolites , mud-cracked dolomicrites and ostracodal micrite, (2) fossil occurrences of Knightia (Herring-type fish) and Equisetum (horsetail), Astephus (catfish), Amyzon (sucker ) and (3) presence of dolomite and aragonite.

The excellent preservation of these mineral-organic laminites and the fossils they contain (Knightia, Astephus, and Amyzon) in shallow-water, near-shore sediments is problematic for the stratified-lake model. Fish buried by sediment in an oxygenated environment would not exhibit complete preservation if exposed to aerobic decay for extended periods. Preservation in this environment is predicted only under conditions of rapid deposition and burial. Near-shore sediments, volcanogenic minerals, low kerogen content, and excellent fossil-fish preservation indicated rapid sedimentation in a near shore, oxygenated, saline environment that is consistent with the playa - lake model.

LLU Discipline

Geology

Department

Geology

School

Graduate School

First Advisor

H. Paul Buchheim

Second Advisor

Ivan G. Holmes

Third Advisor

Conrad D. Clausen

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1983

Date (Title Page)

9-1983

Language

English

Library of Congress/MESH Subject Headings

Shale -- Wyoming -- Analysis

Type

Thesis

Page Count

vii; 69

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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