Abstract

In my efforts to discover source, time, and mechanism of formation of the clastic pipes and dikes found in the region of Kodachrome Basin State Reserve, I found it necessary to understand the depositional environments of the different members and formations within the study area. Mapping and study of the rock units of the Carmel, Entrada, Henrieville, and Tropic-Dakota formations and subsequent comparison with the interpretation of the depositional environments by others working in the same formations in the surrounding region suggest the following history.

The parallel-laminated, siliciclastic sediments and limestones of the Paria River Member of the Carmel Formation indicate a shallow marine platform. The platform sediments are followed by the sandstones, siltstones, shales, and gypsum layers of the Winsor and Wiggler Wash members which, at the present time, have not been interpreted. During the Preuss marine period, the sandstones, siltstones, and shales of the Entrada Sandstone were deposited in a deltaic environment which was a transition between eolian sands to the east and southeast and marine sands in the northwest. After a period of erosion, encroachment by fluvial and eolian deposited shales, siltstones, sandstones, and conglomerates of the Henrieville Formation completed the Jurassic history of the reserve. Early Cretaceous erosion is indicated by an angular unconformity at the top of the Henrieville Formation. Cretaceous coals, sandstones, siltstones, shales, and fossiliferous siltstones and shales of the Tropic-Dakota formations show transgressive- regressive marine phases that cycle between coal swamp, lagoon, and other delta environments. Another unconformity, limited in extent, lies between the Cretaceous and the reserve's Plio-Pleistocene conglomerates. Uplift, due to faulting, allowed the Paria River to erode the Late Cretaceous and Early Tertiary rocks in the Paria Amphitheater and to deposit Plio-Pleistocene channel and sheet conglomerates.

During the period of conglomerate deposition, clastic pipes and dikes intruded the strata of the area. X-ray and thin section analyses of samples from the outer sandstone of the intrusives match samples from both the Paria River and Winsor members of the Carmel Formation. Penetration by the intrusive pipes reached the upper Escalante Member of the Entrada Sandstone. A conglomerate on top of pipe # 38 exhibits pebble counts, heavy minerals, phi-size distributions, and clay x-ray patterns which are similar to both the Plio-Pleistocene channel conglomerates and intrusive sandstones. This is explained by the mixing of intrusive sediments with the channel conglomerates during invasion by this pipe and suggests a Plio-Pleistocene age for the intrusion of the pipes and dikes in the reserve. The proximity of the pipes and dikes to fault zones and the age of intrusion penecontemporaneous with major faulting in the area suggest that the intrusions were the result of seismically generated sediment Tiquification. Neither disruption of the bedding planes nor compressive strain in the country rock is seen around the intrusions. This seems to indicate that scouring of the country rock by the sediments at the advancing head of the intrusion possibly created the space for the pipes and dikes in the invaded formations.

LLU Discipline

Geology

Department

Geology

School

Graduate School

First Advisor

Lanny H. Fisk

Second Advisor

H. Paul Buchheim

Third Advisor

Ivan G. Holmes

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1985

Date (Title Page)

3-1985

Language

English

Library of Congress/MESH Subject Headings

Intrusions (Geology) -- Utah Geology; Structural

Type

Thesis

Page Count

xv; 179

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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