Earth and Planetary Sciences ETDs

Publication Date

6-1-1967

Abstract

The Navajo Sandstone of the Triassic(?) and Jurassic age is approximately 1, 000 feet thick at Navajo Mountain, Utah, and is composed of sets of cliff-forming, highly cross-stratified sandstone and horizontally stratified limestone, siltstone, and sandstone. it is intertongued on a large scale with the underlying, fluvial Kayenta Formation of Triassic(?) age, and is comfortably overlain by the marine Carmel Formation of the Jurassic age.

In the highly cross-stratified Navajo, tabular-planner and wedge planner sets are more common than simple wedge sets, and persistent horizontal bedding and truncation planes distinguish individual sets. Ripple marks, a distinctive type of "graded bedding", and slump deformation characterize foreset beds and laminate, and suggest a largely eolian origin. Large-scale contorted bedding in association with horizontal bedding and truncation planes suggest a high groundwater table during deposition.

Horizontally stratified sets are co-extensive with many of the bedding and truncation planes which serve as excellent stratigraphic marker horizons. A prominent sequence of horizontally stratified limestone, siltstone, and sandstone sets, herein named the Lost Mesa Tongue of the Kayenta Formation, is present in the lower part of the Navajo, and was mapped in detail over an area of about 54 square miles. it is separated from the main body of the Kayenta in its distal portions by more than 300 feet of cross-stratified Navajo sandstone, and its thickness ranges from 0 to 70 feet. gross lithology and internal sedimentary structures indicate a fluvial and lacustrine depositional environment, and cross-bedding azimuths suggests a northwestern-sloping depositional substrate. The limestone is inferred to be algal in part. A peculiar type of sedimentary structure similar to swash lamination is described and indicates contemporaneity of deposition of the Lost Mesa Tongue with a cross-stratified unit of the Navajo.

A northwestern source is interpreted from cross-bedding azimuths for much of the Navajo. Although an eolian origin is indicated, deposition in a coastal regime is inferred because of the presence of Carmel-like beds within the upper part of the formation.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Stuart Alvord Northrop

Second Committee Member

Sherman Alexander Wengerd

Third Committee Member

Charles Brian Read

Language

English

Document Type

Thesis

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