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Date Permissions Signed

2-22-2018

Date of Award

Winter 1987

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

Hansen, Thor A.

Abstract

The Upper Oligocene Sooke Formation, the uppermost unit of the Carmanah Group, is exposed along the southeastern coast of Vancouver Island, British Columbia, where it is part of the Crescent terrane. The Sooke Formation is generally less than 45 meters thick.

Typically, a basal boulder breccia is overlain by interdigitated layers of cross-stratified, often fossiliferous sandstone and conglomerate. Deposition of the Sooke Formation occurred along a steep coast with abundant cliffs, narrow boulder beaches and sandy beaches, and a nearby fluvial source. The conglomerates and breccias were deposited by debris flows, rock falls, and as storm lag deposits. Sandstones were deposited dominantly on the shoreface under both fairweather and storm conditions.

The Sooke Formation sandstones are lithic arenites. The sandstones are texturally immature, and modal grain size is fine sand. Calcite cement is the most common cement, although pyrite, hematite, zeolite, clay, silica, and K-rich cement are also present, indicating a complex diagenetic history. Petrographic studies indicate that the dominant source area for the Sooke Formation was Vancouver Island. Boulders and cobbles were derived locally from the underlying Metchosin Volcanics and Sooke Gabbro, and adjacent Leech River Complex. Sand-sized clasts contain more diverse lithologies derived from several sources on Vancouver Island.

Deposition occurred soon after major movement on the Leech River fault, which is thought to be a suture along which rocks of the Crescent terrane were amalgamated with southern Vancouver Island in an early Tertiary subduction regime. Movement along the Leech River fault prior to deposition of the Sooke Formation caused uplift of the Leech River Complex. The area was tectonically active during deposition. Facies show pulses of shallowing-upwards trends superimposed on a general deepening- upward trend.

Type

Text

Keywords

Geologic history, Sooke Formation

DOI

https://doi.org/10.25710/me63-0m35

Publisher

Western Washington University

OCLC Number

1032335087

Subject – LCSH

Sedimentation and deposition--British Columbia--Vancouver Island; Sediments (Geology)--British Columbia--Vancouver Island; Plate tectonics--British Columbia--Vancouver Island; Geology, Stratigraphic--Oligocene

Geographic Coverage

Vancouver Island (B.C.)

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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