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Date Permissions Signed

5-22-2018

Date of Award

Fall 1985

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Suczek, Christopher A., 1942-2014

Second Advisor

Babcock, R. Scott (Randall Scott)

Third Advisor

Engebretson, David C.

Abstract

The Upper Eocene (Refugian) Quimper Sandstone and overlying Marrowstone Shale document approximately 300 meters of sediment deposited in a tectonically active, shallow marine area during a transgression. The Quimper Sandstone and Marrowstone Shale can be roughly divided into three facies, representing deposition from outer shore face and inner shelf to offshore or outer shelf.

Petrographic analysis of the Quimper Sandstone and Marrowstone Shale indicates geography and hydrodynamic conditions were responsible for a slight petrologic trend in composition such as more feldspar and lithic grains in the lower energy facies. The sandstones are lithic and feldspathic arenites and wackes with abundant feldspars and volcanic lithic fragments. The petrology requires source areas with granitic rocks, andesite, basalt, and chert exposed. Possible source areas include the Crescent Formation, the Coast Plutonic Complex, the San Juan Islands, Vancouver Island, and the North Cascades.

Deposition of the Quimper Sandstone and Marrowstone Shale marks the culmination of movement on the Discovery Bay Fault Zone. These sediments are found overlying the fault zone but not apparently offset by it. Bedding attitudes are consistent across the fault zone. The Discovery Bay Fault Zone has been suggested to be a tectonic suture between the Crescent Terrane and local Tertiary North America. The arrival and subsequent docking of the Crescent Terrane is coincident with a plate reorganization along with a decrease in convergence rates between the Farallon and North American plates. Cessation of movement on the Discovery Bay Fault, along with simple thermal subsidence of the Crescent basalts, deepened the basin, as shown by the sediments grading from hummocky cross-stratified sands of the inner shelf to silty shales of the outer shelf.

Type

Text

Keywords

Petrology, Quimper sandstone, Marrowstone shale

DOI

https://doi.org/10.25710/t0ft-am03

Publisher

Western Washington University

OCLC Number

1047604486

Subject – LCSH

Sedimentation and deposition--Washington (State)--Olympic Peninsula; Sedimentary rocks; Geology, Stratigraphic--Eocene; Sandstone--Washington (State)--Olympic Peninsula; Shale--Washington (State)--Olympic Peninsula

Geographic Coverage

Olympic Peninsula (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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