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Date Permissions Signed

5-16-2018

Date of Award

Fall 1999

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Suczek, Christopher A., 1942-2014

Second Advisor

Brown, Edwin H.

Third Advisor

Mahoney, J. Brian

Abstract

Since Mesozoic time, the western margin of North America has grown through the addition of tectonic terranes, transported atop the subducting paleo-Pacific oceanic plate. The “Baja British Columbia” terrane model postulates accretion of the Insular superterrane at the latitude of southern Mexico and subsequent, margin-parallel translation north to juxtaposition with the western portion of the Intermontane superterrane. After amalgamation, the composite block continued north to its current location. The timing of the proposed translation has not bear well constrained. In the study area, the Okanogan Range batholith of the Intermontane superterrane’s Quesnellia terrane is juxtaposed with the sedimentary and volcanic deposits of the Insular superterrane’s Methow terrane across the Pasayten fault, the superterrane boundary. Deposited upon basement rocks of both superterranes are the Late Cretaceous non-marine conglomerate, sandstone and subordinate volcaniclastics of the Pipestone Canyon Formation. Based on geochemical comparisons between samples from the batholith and plutonic clasts from the formation, a significant proportion of the plutonic debris within Pipestone Canyon Formation strata is inferred to have been derived from the Okanogan Range batholith. The age of the formation, determined by palynology and a zircon fission-track date, is latest Campanian to early Maastrichtian. Therefore, the Pipestone Canyon Formation links the superterranes by 70 Ma and constrains the timing of any northward translation of the Insular superterrane and subsequent, post-amalgamation, northward movement of the Insular-Intermontane superterrane composite unit.

Type

Text

Keywords

Pipestone Canyon Formation, Tectonic terranes, Intermontane superterrane

Publisher

Western Washington University

OCLC Number

1060614599

Subject – LCSH

Formations (Geology)--Washington (State); Sedimentary rocks--Washington (State); Geology, Stratigraphic--Cretaceous

Geographic Coverage

Washington (State)

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.

1999petersonjamesthesismap1.pdf (1209 kB)
Plate 3: Pipestone Canyon Formation Cross-Section

1999petersonjamesthesismap2.pdf (6955 kB)
Blue Buck Mountain Quadrangle

1999petersonjamesthesismap3.pdf (3819 kB)
Plate 2: Pipestone Canyon Formation

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