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Date Permissions Signed

8-31-2018

Date of Award

Spring 1999

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Brown, Edwin H.

Second Advisor

Talbot, James L.

Third Advisor

Babcock, R. Scott (Randall Scott)

Abstract

The Slollicum and Cogburn terranes, metamorphosed country rock within the southern Coast Plutonic Complex, are juxtaposed along a thrust fault together with large slabs of ultramafic rock. The structure and metamorphism along and near this fault are the focus of this study.

Three periods of deformation (D1-D3) affected the study area. D1 structures consist of penetrative foliation and lineations that are attributed to thrust stacking of the Slollicum and Cogburn terranes. Foliation, which parallels the fault contact, dips to the northeast at moderate to steep angles. Lineations have mainly down-dip orientations. D2 structures record the intrusion of the Spuzzum pluton and consist of a foliation, defined mainly by biotite, that parallels the pluton contact. D3 caused rotation and distention of post-tectonic porphyroblasts during localized reactivation of the D1 foliation. D3 is probably a result of orogen-normal contraction that caused large map scale folding that affected the region some time after thrusting ceased.

The metamorphic grade increases to the northeast across the study area from greenschist to amphibolite facies. Three metamorphic events (M1-M3) affect the rocks in the study area. M1, associated with D1, resulted primarily in greenschist facies metamorphism. M2, a result of contact metamorphism from the Spuzzum intrusion, produced the index minerals biotite, hornblende and garnet. M3, a high pressure event, is characterized by an overprint of large garnet and radiating hornblende, which grew over the D1 foliation. These M3 porphyroblasts were then rotated or pulled apart suggesting D3 began after the peak of high pressure metamorphism. M3 also may have produced the randomly oriented hornblende that is observed on foliation surfaces of many Slollicum and Cogburn rocks. Terrane stacking must have taken place after 146 Ma, which is the U/Pb zircon age of the Slollicum rocks (Walker, in Bennett, 1989), and prior to the 96 Ma age (Brown and Walker, 1993) of the Spuzzum pluton.

Type

Text

Keywords

Talc Creek area, Harrison Lake B.C., Foliation

Publisher

Western Washington University

OCLC Number

1088420359

Subject – LCSH

Geology, Structural--British Columbia--Harrison Lake Region; Metamorphic rocks--British Columbia--Harrison Lake Region; Metamorphism (Geology)--British Columbia--Harrison Lake Region

Geographic Coverage

Harrison Lake Region (B.C.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this thesis 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.

Included in

Geology Commons

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