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Date Permissions Signed

6-3-2018

Date of Award

Summer 2008

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Housen, Bernard Arthur

Second Advisor

Hirsch, David M., 1969-

Third Advisor

Burmester, Russell F.

Abstract

The mid-Cretaceous Skeena Group of British Columbia is a sedimentary continental margin deposit that overlies the lower Jurassic Hazelton Group of the Stikine Terrane. Nine paleomagnetic sites were collected in 2006 and 2007, demagnetized thermally in 50-15°C steps, and high temperature components fit using principal component analysis. A new Ar40/Ar39 age of 93.9 ± 0.6 Ma for a flow of the Rocky Ridge Formation was also collected.

Three volcanic sites of the Rocky Ridge Volcanics possess coherent magnetizations, but did not prove useful. Five of six sedimentary sites from the Rocher de Boule and Bulkley Canyon Formations appear more likely to retain a primary magnetization. Curie temperature analysis indicates the primary carrier of magnetic remanence is magnetite. Hysteresis and direct field demagnetization data indicate the magnetite is primarily multi-domain in the volcanic sites and possess a mix of single and multi-domain grains in the sedimentary rocks, which may account for the more likely primary remanence from the sedimentary formations

When subjected to a bootstrap fold test, the sedimentary sites have maximum grouping at 40% untilting, but the hypotheses that the magnetization was acquired either before or after tilting cannot be rejected at the 95% confidence level. An inclination-only paleolatitude analysis was used to estimate paleolatitude as different declinations between sites suggest rotation between sites. The resulting paleolatitude for the Skeena Group is ~57°± 21°. This is equivalent to a location ~1150 ± 2000 km south of the expected latitude with respect to North America.

Uranium-lead ages of detrital zircons from a sample of the Rocher de Boule Formation were obtained using laser ablation inductively coupled mass spectrometry. These ages form several Mesozoic peaks indicating that the majority of zircons came from Stikine terrane units and Mesozoic arc volcanism. A Mississippian peak with some Proterozoic aged grains suggests a source from the Yukon-Tanana terrane. No Archean-aged grains were found.

Type

Text

Keywords

Geochronology, Paleomagnetism, Stikine terrane

DOI

https://doi.org/10.25710/v7mv-eh04

Publisher

Western Washington University

OCLC Number

1047603241

Comments

The CD-Rom is unavailable.

Subject – LCSH

Geology, Structural--British Columbia--Skeena Group; Paleomagnetism--British Columbia--Skeena Group; Geology, Stratigraphic--Cretaceous

Geographic Coverage

Skeena Group (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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