BASIN ARCHITECTURE OF THE NORTH OKANAGAN VALLEY FILL, BRITISH COLUMBIA sandy Vanderburgh B.Sc., University of Calgary I984 M.Sc., University of Calgary 1987 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Geography 0 Sandy Vanderburgh SIMON FRASER UNIVERSITY July 1993 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. APPROVAL ' Name: Sandy Vanderburgh Degree: Doctor of Philosophy Title of Thesis: Basin Architecture Of The North Okanagan Valley Fill, British Columbia Examining Committee: Chair: Alison M. Gill Associate Professor Dr. M.C. Roberts, Protessor Senior Supervisor Idr. H. Hickin, professor Dr. Dirk Tempelman-Kluit, Director Cordilleran Division, Geological Survey of Canada Dr. R.W. Mathewes, Professor, Department of Biological Sciences Internal Examiner Dr. James A. Hunter, Senior scientist & Program Co-ordinator, Terrain Sciences Division Geological Survey of Canada External Examiner Date Approved: Julv 16. 1993 PARTIAL COPYRIGHT LICENSE 8* I hereby grant to Simon Fraser University the right to lend my thesis, projector extended essay (the title of which is shown below) to users of the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this work for scholarly purposes may be granted by me or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without my written permission. Title of Thesis/Project/Extended Essay Basin Architecture Of The North Okanarran Valley Fill, British Columbia Author: (signature) Sandy Vanderburrrh (name) (date) ' ABSTRACT The North Okanagan Valley occupies an elongate basin (-45 km long by -3 km wide) situated in the Cordilleran physiographic region of the southern Interior of British Columbia. Depth to bedrock in the North Okanagan Basin is at least 680 m below the valley floor and 2200 m below the surrounding Thompson Plateau and Shuswap Highlands. The volume of sediment stored within the basin is estimated to be about 49 km3 and the study findings suggest that the basin fill was mainly deposited after -19 ka during late Wisconsin glaciation and deglaciation. Analysis of 16 km of high resolution reflection seismic profiles and 30 lithologic logs was carried out to delineate and interpret the basine'architectureof the valley fill and provide an interpretive framework for basin architectures of other glaciated Cordilleran valleys. The main objective of this study was to establish the three-dimensional basin architecture of the North Okanagan Valley. The seismic and lithologic data were integrated using a depositional systems approach which revealed four distinct depositional systems that characterize the basin architecture: the Fluvio-Glacial, Glaciolacustrine, Alluvial Fan, and Fluvial Systems. The clastic fill of the basin shows an overall fining upward trend from basal, coarse-grained, stratified and poorly stratified sand and gravel of the Fluvio-Glacial System to the Glaciolacustrine System. The Glaciolacustrine System is exposed at the surface and fines upward from glaciolacustrine fine sand to silt and clay. The Alluvial Fan System interfingers the Fluvio-Glacial and Glaciolacustrine Systems and plays an important role in the overall geometry of the basin architecture. Channel sand and silt of the Fluvial System are incised into the upper part of the Glaciolacustrine System. w From this data a three-dimensional model is proposed for the North Okanagan Basin that defines the architecture of the basin fill and highlights the geomorphic environment during deglaciation. The model illustrates that during ice advance and retreat thick sequences of coarse-grained, stratified sediments were deposited adjacent to the glacial ice. Blockage of the Okanagan Valley and formation of Glacial Lake Penticton resulted in thick accumulations of glaciolacustrine silt and clay in a setting which was relatively free of stagnant ice complexes. During, and soon after deglaciation, alluvial fans were deposited into the basin by mass movement processes that redistributed unstable glacigenic sediments. On the valley floor, the Shuswap River is incised into the glaciolacustrine sediments and is representative of contemporary geomorphic processes. DEDICATION This work is dedicated to my nieces, Kelsy and Kayla, for the happiness you bring to me. ACKNOWLEDGMENTS I would like to thank my senior supervisor, Dr. Michael C. Roberts, for his guidance, friendship, and criticism; I have benefited from the practical experience you passed along to me 'in the field' and will not forget the soggy summer of '91. Drs. Edward (Ted) J. Hickin and Dirk Tempelman-Kluit provided valuable advice and comments throughout the course of this study. Special thanks also goes out to Drs. Jim Hunter and Rolf Mathewes, whose comments were helpful and appreciated. Drs. Sue Pullan and Jim Hunter of the Geological Survey of Canada, Terrain Sciences Division, permitted the use of the Vernon seismic lines and provided computer and plotting facilities for preparation of the final printouts. Special thanks is also extended to the staff of the Geography Department and landowners in the North Okanagan Valley. Financial support was provided by a National Science and Engineering Research Council of Canada (NSERCC) Operating Grant and a Simon Fraser University Special Research Grant for investigating the "Tertiary-Quaternary Fill of the Okanagan Valley", both awarded to Dr. Roberts. Funding was also provided in the form of a Graduate Entrance Scholarship, Graduate Fellowships, and a President's Research Grant awarded to the author. I would also like to thank the British Columbia Ministry of Environment, Groundwater Division, for the provision of well logs and core samples. This dissertation would not have been possible without exceptional field crews - special thanks to David Lye, Steve Deichman, and Mike and Ev Roberts. Your strong backs, determination, and enthusiasm were greatly appreciated during those 'dog day' Okanagan afternoons. My good friend Dr. Harry Jol provided invaluable assistance during initial seismic testing in the Vernon area. To my buddies Olav Lian, Don McPhee, and Dr. Gregory Brooks, thanks for all the 'shop talk' over beers and during hikes; Arnie nights and Jack Daniels forever! Tanya Lukie provided many useful editorial comments on various drafts of the thesis and assisted in final preparation of the document. Many thanks for your kindness, moral support, and for showing up at the right time in my life. Last, but not least, I would like to thank my family for always being there. Your understanding, support, and patience has been greatly appreciated throughout my academic career. TABLE OF CONTENTS PAGE ... ABSTRACT .......................................................................................................... 111 DEDICATION ........................................................................................................ v ACKNOWLEDGMENTS ....................................................... .............................. vi ... TABLE OF CONTENTS ..................................................................................... VIII LIST OF TABLES ...............................................................................................xiii LIST OF FIGURES .............................................................................................. xv CHAPTER ONE .INTRODUCTION ......................................................... ;........... 1 Introduction .......................................................................................... 1 The North Okanagan Valley: Previous Investigations ........................ 4 Basin Architecture of the North Okanagan Valley ............................... 7 Objectives of the Study ..................................................................... 14 CHAPTER TWO .PHYSICAL SETTING AND PREVIOUS RESEARCH .......... 16 2.1 The Study Area ................................................................................. 16 2.2 Previous Geological Investigations. Tectonics. and Geology of the Study Area ........................................................................................18 2.2.1 Previous Geological Investigations ..................................... 18 2.2.2 Tectonics ............................................................................. 20 2.2.3 Geology of the Study Area ..................................................24 2.3 Quaternary Deposits. Stratigraphy. and Holocene Deposits ............. 26 2.3.1 Quaternary Deposits and Stratigraphy ................................ 26 2.3.2 Holocene Climate and Surficial Sediments ......................... 30 2.4 Glaciation. Glacial Lakes and Silt Deposits .......................................32 2.4.1 Styles of Glaciation .............................................................. 32 2.4.2 Glacial Lakes ....................................................................... 33 2.4.3 Lacustrine Silt ...................................................................... 37 CHAPTER THREE .RESEARCH METHODS ................................................... 40 3.1 Introduction .......................................................................................