Geophysical Modeling in the Cabot Strait - St
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GEOPHYSICAL MODELING IN THE CABOT STRAIT - ST. GEORGE’S BAY AREA BETWEEN CAPE BRETON ISLAND AND SOUTHWESTERN NEWFOUNDLAND, CANADA By Louis Zsámboki Honours B. Sc. (Earth Sciences), McMaster University Hamilton, Ontario 2009 Thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science (Geology) Acadia University Fall Graduation 2012 © by Louis Zsámboki, 2012 This thesis by Louis Zsámboki was defended successfully in an oral examination on September 6th, 2012. The examining committee for the thesis was: __________________________________ Dr. Kirk Hillier, Chair __________________________________ Dr. Fraser Keppie, External Reader __________________________________ Dr. Robert P. Raeside, Internal Reader __________________________________ Dr. Sandra M. Barr, Supervisor __________________________________ Dr. Sonya A. Dehler, Supervisor __________________________________ Dr. Ian S. Spooner, (Acting) Head of Department This thesis is accepted in its present form by the Division of Research and Graduate Studies as satisfying the thesis requirements for the degree of Master of Science (Geology). ……………......................…………………. iii I, Louis Zsámboki, grant permission to the University Librarian at Acadia University to reproduce, loan or distribute copies of my thesis in microform, paper or electronic formats on a non-profit basis. I, however, retain the copyright in my thesis. ______________________________________ Author ______________________________________ Supervisor ______________________________________ Date iv TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................... ix ACKNOWLEDGEMENTS ............................................................................................. xiii ABSTRACT ..................................................................................................................... xiv Page CHAPTER 1 INTRODUCTION .....................................................................................1 1.1 Purpose of the Study .....................................................................................................1 1.2 Location of the Study Area ...........................................................................................2 1.3 Geological Background and Previous Work ................................................................2 1.3.1 Introduction ...................................................................................................2 1.3.2 Cape Breton Island ........................................................................................3 1.3.3 Southwestern Newfoundland ........................................................................5 1.3.4 Offshore Geology.........................................................................................7 1.4 Previous Geophysical Work .........................................................................................8 1.5 Methods ......................................................................................................................10 1.5.1 Geophysical Data and Modeling ................................................................10 1.5.2 Physical Property Data ...............................................................................11 CHAPTER 2 GEOLOGIC SETTING ...........................................................................19 2.1 Introduction ...............................................................................................................19 2.2 Bras d’Or Terrane .....................................................................................................19 2.2.1 Introduction ................................................................................................19 2.2.2 Bras d’Or Gneiss ........................................................................................21 2.2.3 George River Metamorphic Suite ..............................................................22 v 2.2.4 Ca. 565-555 Ma Plutonic Units .................................................................24 2.2.4.1 Mafic to intermediate plutons ......................................................25 2.2.4.2 Intermediate to felsic plutons ......................................................26 2.2.5 Ca. 500 Ma Plutonic Units .........................................................................28 2.2.6 Bourinot Belt ..............................................................................................29 2.3 Aspy Terrane .............................................................................................................29 2.3.1 Introduction ................................................................................................29 2.3.2 Cape North Group ......................................................................................30 2.3.3 Money Point Group....................................................................................31 2.3.4 Clyburn Brook Formation ..........................................................................31 2.3.5 Cheticamp Lake Gneiss .............................................................................32 2.3.6 Glasgow Brook Orthogneiss ......................................................................32 2.3.7 Cameron Brook Granodiorite ....................................................................33 2.3.8 Neils Harbour Gneiss .................................................................................33 2.3.9 Ingonish Island Rhyolite ............................................................................34 2.3.10 Black Brook Granitic Suite ........................................................................34 2.3.11 Wilkie Sugarloaf and Similar Granite Plutons...........................................35 2.3.12 Fisset Brook Formation..............................................................................35 2.4 Blair River Inlier .......................................................................................................35 2.4.1 Mesoproterozoic Rocks .............................................................................35 2.4.2 Lowland Cove Formation ..........................................................................37 2.5 Carboniferous Units in Cape Breton Island ..............................................................38 2.5.1 Horton Group .............................................................................................38 2.5.2 Windsor Group...........................................................................................38 vi 2.5.3 Mabou Group .............................................................................................39 2.5.4 Morien Group.............................................................................................39 2.5.5 Pictou Group ..............................................................................................39 2.6 Southwestern Newfoundland ....................................................................................40 2.6.1 Introduction ................................................................................................40 2.6.2 Humber Zone .............................................................................................41 2.6.3 Notre Dame Subzone .................................................................................44 2.6.4 Port-aux-Basques and Meelpaeg Subzones (Gander Zone) .......................46 2.6.5 Exploits Subzone .......................................................................................48 2.6.6 Burgeo Subzone .........................................................................................50 2.6.7 Silurian-Devonian Plutons .........................................................................51 2.7 Carboniferous Rocks in Southwestern Newfoundland ............................................53 2.8 Offshore Geology......................................................................................................54 CHAPTER 3 METHODS ..............................................................................................62 3.1 Sources of Digital Magnetic and Gravity Data .........................................................62 3.2 Magnetic Data ...........................................................................................................62 3.3 Gravity Data ..............................................................................................................65 3.4 Magnetic Susceptibility Data ....................................................................................66 3.5 Specific Gravity Data ................................................................................................67 3.6 Seismic Data .............................................................................................................68 3.7 Potential Field Modeling...........................................................................................69 vii CHAPTER 4 RESULTS ................................................................................................74 4.1 Introduction ...............................................................................................................74 4.2 Magnetic Maps..........................................................................................................74 4.2.1 Total Magnetic Field ..................................................................................74