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).
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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
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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
4.2.2 First Vertical Derivative ...... 76
4.2.3 Second Vertical Derivative ...... 78
4.2.4 Downward Continuation ...... 80
4.3 Gravity Maps ...... 81
4.4 Seismic Data ...... 82
4.4.1 Lithoprobe/Frontier Geoscience Lines 86-4 and 86-5A ...... 83
4.4.2 Industry Seismic Lines – Cabot Strait and Sydney Basin...... 84
4.4.3 Industry Seismic Lines – St. George’s Bay ...... 85
4.5 Physical Property Data ...... 86
4.5.1 Pre-Carboniferous Rocks – Cape Breton Island ...... 86
4.5.2 Pre-Carboniferous Rocks – Newfoundland ...... 88
4.5.3 Carboniferous Units – Cape Breton Island ...... 88
4.5.4 Carboniferous Units – Newfoundland ...... 89
4.6 Potential Field Models ...... 89
4.6.1 Model Parameters ...... 89
4.6.2 Profile 1 ...... 90
4.6.3 Profile 2 ...... 91
4.6.4 Profile 3 ...... 92
4.6.5 Profile 4 ...... 93
4.6.6 Profile 5 ...... 94
4.6.7 Profile 6 ...... 95
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CHAPTER 5 DISCUSSION ...... 112
5.1 Geophysical Implications for Onshore Geology...... 112
5.1.1 Cape Breton Island ...... 112
5.1.2 Southwestern Newfoundland ...... 115
5.2 Geophysical Implications of Offshore Geology ...... 118
5.2.1 Major faults and terrane boundaries ...... 118
5.2.2 Interpretation of basement units on profile models ...... 121
5.3 Limitations of the Study...... 124
CHAPTER 6 CONCLUSIONS ...... 143
REFERENCES ...... 146
APPENDIX A: Measured density (g/cm3) and susceptibility (x10-3 SI units) in pre-Carboniferous samples from northeastern Cape Breton Island...... 167
APPENDIX B: Summary of density and magnetic susceptibility data used in
this study ...... 200
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LIST OF FIGURES
Figure Page
1.1 Total field magnetic anomaly map of Cape Breton Island, southwestern
Newfoundland and adjacent areas...... 13
1.2 Bathymetric map of the area between Cape Breton Island and southwestern
Newfoundland ...... 14
1.3 Map of part of the northern Appalachian orogen showing major geological
components...... 15
1.4 Simplified geological map showing rock units in the Aspy and Bras d’Or terranes
...... 16
1.5 Map of the Cabot Strait and surrounding area showing depth to pre-Mesozoic,
pre-Carboniferous, and pre-Paleozoic basement...... 17
1.6 Legend for the map in Figure 1.5 ...... 18
2.1 Geologic map of eastern Cape Breton Island showing the major rock units ...... 58
2.2a Geologic map of southwestern Newfoundland...... 59
2.2b Legend for Fig. 2.2a...... 60
2.3 Geological map of the Cabot Strait area ...... 61
3.1 Location of on-land gravity survey measurements and off-shore tracklines of
marine gravity surveys...... 70
3.2 Geological map of northeastern Cape Breton Island modified from Figure 2.1
showing locations of samples measured for magnetic susceptibility...... 71
3.3 Locations of seismic reflection line interpretations used in this study...... 72
3.4 Map showing the locations of the six cross-sections used for forward modeling
using magnetic and gravity data ...... 73
x
4.1 Total magnetic field anomaly map of the study area...... 96
4.2 First derivative of the total magnetic field anomaly map...... 97
4.3 Second derivative of the total magnetic field anomaly map...... 98
4.4 Downward continuation by 400 m of the total magnetic field produced in the
present study as described in Chapter 3...... 99
4.5 Bouguer (onshore) and free-air (offshore) gravity anomaly map ...... 100
4.6 Map showing calculated horizontal gradient of gravity anomaly data in Figure 4.5
with illumination at an azimuth of 315o...... 101
4.7 Summary of values for density (ρ in kg/m3) and magnetic susceptibility (k in x10-3
SI units) used for units in models ...... 102
4.8 Enlargement of the Cabot Strait area from the first derivative map ...... 103
4.9 Model for profile 1 produced in GM-SYS...... 104
4.10 Model for profile 2 produced in GM-SYS...... 105
4.11 Model for profile 3 produced in GM-SYS...... 106
4.12 Enlarged view of the area around the Ingonish magnetic anomaly from the first
derivative of the total magnetic field anomaly map...... 107
4.13 Model for profile 4 produced in GM-SYS...... 108
4.14 Model for profile 5 produced in GM-SYS ...... 109
4.15 Enlargement of the St. Georges Bay area from the first derivative magnetic
anomaly map ...... 110
4.16 Model for profile 6 produced in GM-SYS ...... 111
5.1a Total magnetic field anomaly map of northeastern Cape Breton Island with
geologic map overlay...... 126
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5.1b First vertical derivative magnetic anomaly map of northeastern Cape Breton
Island with geologic map overlay ...... 127
5.1c Second vertical derivative magnetic anomaly map of northeastern Cape Breton
Island with geologic map overlay ...... 128
5.1d Bouguer (on shore) and free-air (offshore) gravity anomaly map of northeastern
Cape Breton Island with geologic map overlay ...... 129
5.1e Map showing horizontal gradient of gravity anomalies with illumination at an
azimuth of 315o ...... 130
5.2a Total magnetic field anomaly map of southwestern Newfoundland with geologic
map overlay ...... 131
5.2b First vertical derivative magnetic anomaly map of southwestern Newfoundland
with geologic map overlay ...... 132
5.2c Second vertical derivative magnetic anomaly map of southwestern Newfoundland
with geologic map overlay ...... 133
5.2d Bouguer (onshore) and free-air (offshore) gravity anomaly map of southwestern
Newfoundland with geologic map overlay ...... 134
5.2e Map showing horizontal gradient of gravity anomalies with illumination at an
azimuth of 315o ...... 135
5.3a Total magnetic field anomaly map of the study area with geologic map overlay
...... 136
5.3b First derivative of the total magnetic field anomaly map of the study area with
geologic map overlay ...... 137
5.3c Second derivative of the total magnetic field anomaly map of the study area with
geologic map overlay ...... 138
xii
5.3d Bouguer (onshore) and free-air (offshore) gravity anomaly map of the study area
with geologic map overlay ...... 139
5.3e Horizontal gradient of gravity anomaly with illumination at an azimuth of 315o
with geologic map overlay ...... 140
5.4 First vertical derivative magnetic map with geologic map overlay and inferred
terrane correlation between Cape Breton Island and Newfoundland ...... 141
5.5 First vertical derivative magnetic map of the study area with geologic map overlay
and pre-Carboniferous units inferred from GM-SYS forward modeling profiles
...... 142
xiii
ACKNOWLEDGEMENTS
I would like to thank the people who made this project possible. First and foremost I offer my sincerest gratitude and appreciation to my supervisors, Drs. Sandra
M. Barr and Sonya Dehler for their assistance, advice, encouragement, and financial support and who have supported me throughout my thesis preparation with their patience and knowledge. I am grateful to the Geological Survey of Canada for allowing me access to their databases and use of their software. A special thanks to Lori Cook from the
Newfoundland and Labrador Department of Natural Resources for providing a more recent magnetic data set to use for the St. George’s Bay area. I also extend my gratitude to all the professors, students and staff members of the Department of Earth and
Environmental Science at Acadia University for their kind and friendly support throughout my thesis work. The contribution of all the people mentioned above allowed me to complete this thesis, and helped to get through the last fifteen months.
The financial support for this project was provided by a Services Contract with
Natural Resources Canada and an Acadia University Graduate Award.
xiv
ABSTRACT
Magnetic and gravity data from northeastern Cape Breton Island, southwestern
Newfoundland, and the intervening Cabot Strait area were compiled, and a series of maps displaying magnetic (filtered total field, first and second derivative, and downward continuation) and gravity (Bouguer anomaly onshore, free-air anomaly offshore and horizontal gradient) information was generated using UNIX-based GMT software. With further constraints from previously published seismic reflection interpretations and detailed maps of onshore geology, six 2D subsurface models were generated with GM-
SYS 4.2 2D modeling software. Based on geophysical signatures, anomalies in the offshore were matched to onshore faults, rock units, and pre-Carboniferous terranes. The
Cabot Fault separates Grenvillian basement to the northwest from peri-Gondwanan
Aspy/Port-aux-Basques/Exploits basement to the southeast. The Cape Ray Fault merges with the Cabot Fault so that Notre Dame subzone rocks do not extend into the Cabot
Strait area. Linear magnetic anomalies extending from the Port-aux-Basques subzone in southwestern Newfoundland to the Aspy terrane of Cape Breton Island are inferred to be a result of orthogneissic plutons in Aspy/Port-aux-Basques/Exploits basement rock.
Magnetic halos in the Cabot Strait appear to be caused by Silurian-Devonian plutons like those in the Burgeo Batholith. The Aspy-Bras d’Or terrane boundary is located north of the Ingonish magnetic anomaly which was resolved into five components representing
Late Neoproterozoic dioritic and granodioritic plutons of the Bras d’Or terrane and the
Ingonish Island Rhyolite. The Bras d’Or terrane can be traced to the Grey River area in southern Newfoundland. A model in the Bay St. George sub-basin showed Grenvillian basement characteristic of the Humber Zone, overlain by the salt-bearing Codroy Group and clastic Barachois Group.
1.0 INTRODUCTION
1.1 Purpose of the Study
The purpose of this study is to further investigate pre-Carboniferous geology and geological correlations between Cape Breton Island and southwestern Newfoundland using geophysical data. Geophysical modeling using potential field (magnetic and gravity) data supported by seismic reflection data are used as a basis for interpreting pre-
Carboniferous units and structures and hence refining previous interpretations. One feature of particular interest is a large positive magnetic anomaly centered 25 km east of
Cape Breton Island which disrupts the otherwise mainly linear anomalies in the area (Fig.
1.1).
The specific goals of this study are to:
1. compile magnetic and gravity data from the study area and produce filtered
magnetic and gravity maps to compare to geological maps in both northeastern
Cape Breton Island and southwestern Newfoundland and extrapolate the geology
into offshore areas.
2. use these maps to select 6 suitable locations for constructing 2D subsurface
models, and compile and interpret available seismic reflection data to provide
additional constraints on the 2D models.
3. build 2D models from magnetic, gravity, and seismic data along these 6 lines,
and make observations and interpretations based on these models.
4. use the maps and models to interpret onshore and offshore geology between
northeastern Cape Breton Island and southwestern Newfoundland.
2
1.2 Location of the Study Area
The study area is approximately 20,000 km2 and includes northeastern Cape
Breton Island, southwestern Newfoundland, and the intervening offshore area (Fig. 1.1).
In the offshore, the study area includes the Cabot Strait and northern part of the Sydney
Basin, as well as St. George’s Bay in southwestern Newfoundland (Fig. 1.1). Water depths are generally less than 200 m, except in the Laurentian Channel where depths exceed 400 m (Fig. 1.2). In terms of geological features, it encompasses parts of the
Blair River Inlier and Aspy and Bras d’Or terranes of northeastern Cape Breton Island and their inferred offshore extensions across the Cabot Strait and into southwestern
Newfoundland (Fig. 1.3).
1.3 Geological Background and Previous Work
1.3.1 Introduction
The Appalachian orogen was formed as a result of closing of the ancient Iapetus and Rheic oceans (e.g., van Staal 2007). This process caused deformation of Paleozoic and older rocks in the orogen. The Appalachian orogen is narrower and more highly deformed in southwestern Newfoundland and Cape Breton Island compared to elsewhere in Newfoundland and in New Brunswick and New England. This difference has been attributed to the position of the geological components of this area on both Laurentian and Gondwanan promontories during collision (Lin et al. 1994).
In southwestern Newfoundland, the Cabot (or Long Range) Fault separates the
Grenvillian Humber Zone from the mainly oceanic rocks of the peri-Laurentian Notre
Dame subzone (Fig. 1.3). However in Cape Breton Island the Notre Dame subzone appears to be absent and peri-Gondwanan rocks of the Aspy terrane are in faulted contact 3 with the Grenvillian Blair River Inlier, correlated with Grenvillian basement rocks in the
Humber Zone (Barr and Raeside 1989; Barr et al. 1998).
1.3.2 Cape Breton Island
Cape Breton Island is divided (from north to south) into the Blair River Inlier and
Aspy, Bras d’Or, and Mira terranes (Fig. 1.3). The Mira terrane is part of Avalonia and hence similar to the Avalon zone of Newfoundland located east of the Dover-Hermitage
Bay Fault (Hibbard et al. 2006). The Mira terrane is not included in the present study area. The Aspy and Bras d’Or terranes are both considered to be part of Ganderia, the part of the Central Mobile Belt located east of the Red Indian Line in Newfoundland and equivalent areas on the mainland (Hibbard et al. 2006). The Bras d’Or terrane is characterized by low-pressure cordierite-andalusite (or sillimanite) gneiss and low- to high-grade metasedimentary and minor metavolcanic rocks, both intruded by abundant ca. 565-555 Ma and ca. 500 Ma plutonic rocks (Fig. 1.4; Raeside and Barr 1990; Barr et al. 1990). The older plutons (565-555 Ma) are composed of diorite, tonalite, granodiorite and granite and interpreted to have formed in a continental margin subduction zone (e.g.,
Farrow and Barr 1992). The ca. 500 Ma plutons are of granitic composition and may have formed by crustal melting during postorogenic uplift or during periods of localized extension within the terrane (White et al. 1994). The variation in level of exposure in
Bras d’Or terrane is consistent with the Bras d’Or terrane having been thrust over the
Aspy terrane, with subsequent erosion exposing deeper levels of the terrane near its boundary with the Aspy terrane (Barr et al. 1995).
The Aspy terrane is characterized by Ordovician and Silurian metasedimentary and metavolcanic rocks affected by Devonian thermal events and widespread granitic 4 magmatism (Fig. 1.4; Barr and Jamieson 1991). The metasedimentary and metavolcanic rocks are assigned to a number of different units based on age and stratigraphic, structural and metamorphic characteristics (Barr and Jamieson 1991; Lin et al. 2007). Of particular importance in the present study are the units in the northeastern part of the Aspy terrane, including the Money Point Group, Cape North Group, Cheticamp Lake Gneiss, and
Clyburn Brook Formation (Fig. 1.4). The major plutonic units in the Aspy terrane in that area are the ca. 375 Ma, mainly granitic Black Brook Granitic Suite (Yaowanoiyothin and Barr 1991) and the ca. 402 Ma Cameron Brook Granodiorite (Dunning et al. 1990a).
The Neils Harbour Gneiss includes components of the Cameron Brook Granodiorite,
Black Brook Granitic Suite, and biotite-rich paragneiss of uncertain protolith and age
(Yaowanoiyothin and Barr 1991). Also potentially important in the present study is the
Ingonish Island Rhyolite, a magnetite-rich rhyolite that occurs only on Ingonish Island
(Barr and Raeside 1998; Fig. 1.4). St. Paul Island, located in the Cabot Strait about 25 km east of the northeastern tip of Cape Breton Island (Fig. 1.5), consists of rocks inferred to correlate with those of the Aspy terrane (Lin 1994; Barr et al. 1998). These units and their relevance to this study are described in more detail in Chapter 2.
The Blair River Inlier is composed of gneiss, syenite and anorthosite that have been metamorphosed partly to granulite facies with overprinting at amphibolite and greenschist facies conditions (Barr et al. 1998). The Blair River Inlier has age, compositional, and metamorphic similarities with Grenvillian rocks in the Humber Zone of Newfoundland, although in the Blair River Inlier the Grenvillian rocks were affected extensively by Silurian orogenic activity dated at 425 Ma based on U-Pb ages from titanite (Miller et al. 1996; Barr et al. 1998). Also in contrast to the Humber Zone, the
Blair River Inlier lacks a Cambrian-Ordovician passive margin sedimentary sequence, 5 other than possibly some minor calc-silicate and marble lenses interpreted to be either xenoliths or fault-bound enclaves in the gneissic rocks (Barr et al. 1998; Miller and Barr
2000). The absence or near absence of a cover sequence may be the result of the Blair
River Inlier being situated on the St. Lawrence promontory during Silurian orogenesis, such that cover rocks were most likely eroded during uplift (Barr et al. 1998). Ca. 580
Ma gabbroic dikes in the Blair River Inlier are similar to other mafic units found along the northeastern Laurentian margin associated with opening of the Iapetus Ocean (Miller and Barr 2004).
Devonian and Carboniferous sedimentary rocks of the Maritimes Basin overlie the older rock units around the periphery of the Cape Breton Highlands (Fig. 1.4, 1.5).
Locally, Devonian sedimentary and bimodal volcanic rocks of the Fisset Brook
Formation underlie the Carboniferous units, forming the early fill in extensional basins that developed after Devonian orogenesis. The more widespread Horton Group occupies fault-bounded basins across Atlantic Canada (e.g., Hamblin and Rust 1989; Gibling et al.
2008). It is overlain by the Windsor Group, which also oversteps pre-Carboniferous units and includes clastic rocks as well as carbonate and evaporite rocks deposited in a marine environment. The Windsor Group is overlain conformably by lacustrine rocks of the
Mabou Group, which is in turn unconformably overlain by fluvial/lacustrine rocks of the
Morien Group and red mudstone and sandstone of the Pictou Group, which extends in places into the Permian (e.g., Pascucci et al. 2000).
1.3.3 Southwestern Newfoundland
The Cape Ray Fault Zone in southwestern Newfoundland is generally interpreted to connect with the Red Indian line, the boundary between Laurentia and peri-Laurentian 6 terranes (Notre Dame subzone) and Ganderia (Exploits subzone and Gander zone) in central Newfoundland. The Notre Dame subzone, Exploits subzone, and Gander zone make up the Central Mobile Belt of older Appalachian terminology (Fig. 1.3). These zones and subzones are well defined in central Newfoundland but become narrow and converge in southwestern Newfoundland, and their continuation under the Cabot Strait and into Cape Breton Island is uncertain (e.g., Lin et al. 2007).
The Humber zone preserves the sedimentary record of the Laurentian margin that formed on ca. 1.0-1.5 Ga Grenville basement (e.g., Waldron and van Staal 2001).
Waldron and van Staal (2001) proposed a two-stage rifting model for the margin, with the first stage during the Late Proterozoic forming the Iapetus Ocean, and the second stage during the Early Cambrian (550 Ma) forming the Humber (or Taconic) Seaway and separating the Dashwoods microcontinent (Notre Dame subzone in Fig. 1.5) from the rest of Laurentia. During this time a passive margin was built on the western margin of the
Humber Seaway. Subsequently during the Late Cambrian-Early Ordovician, the
Dashwoods microcontinent collided with a subduction zone to the east, resulting in closure of the Humber Seaway and causing the Taconic Orogeny (Waldron and van Staal
2001). In the St. George’s Bay area, the Laurentian margin includes Lower Cambrian to
Lower Ordovician carbonate shelf rocks which overlie Upper Neoproterozoic to
Cambrian rift facies and Grenvillian basement (Fig. 1.5; Waldron and van Staal 2001).
Metasedimentary and metavolcanic rocks in the area between the Cape Ray Fault
Zone and Bay d’Est Fault Zone are generally assigned to Ganderia (e.g., Valverde-
Vaquero et al. 2000; Hibbard et al. 2006; Lin et al. 2007), with the Isle-aux-Morts Fault separating the Gander zone part (Port-aux-Basques and Meelpaeg subzones) from the
Exploits subzone part (Fig. 1.5, 1.6). South of the Bay d’Est Fault Zone, Silurian rocks 7 lie unconformably on Late Neoproterozoic-Late Cambrian rocks, a relationship similar to that inferred in the Aspy terrane of Cape Breton Island (e.g., Lin et al. 2007). The Late
Neoproterozoic rocks include granodiorite and tonalite, together with porphyry intrusions and metavolcanic rocks, yielding U-Pb zircon ages ranging from ca. 686-548 Ma but mostly from ca. 585-557 Ma (Valverde-Vaquero et al. 2006). Also present are Late
Cambrian intrusions dated at ca. 499-495 Ma (Valverde-Vaquero et al. 2006). Some workers in Newfoundland have interpreted this area to be part of Avalonia, rather than
Ganderia, based on the Neoproterozoic ages (e.g., O’Brien et al. 1991; Valverde-Vaquero et al. 2006).
Carboniferous sedimentary rocks of the Maritimes Basin also occur in southwestern Newfoundland west of the Cabot Fault in the Bay St. George sub-basin
(Fig. 1.5). In that area they are termed the Anguille, Codroy, and Barachois groups, equivalent to the Horton, Windsor, and Mabou-Morien-Pictou groups, respectively, in
Cape Breton Island (e.g., Langdon and Hall 1994).
1.3.4 Offshore Geology
Carboniferous sedimentary rocks are generally less than 2 km thick onshore in
Cape Breton Island and southwestern Newfoundland but thicken significantly in the offshore in the Sydney and Magdalen basins (Fig. 1.5). Both basins are part of the regional Maritimes Basin, which includes most Carboniferous rocks in Atlantic Canada
(e.g., Gibling et al. 1987). In the Sydney Basin, the Horton Group rocks fill extensional basins within pre-Carboniferous “basement blocks”, bordered by south-dipping master fault zones (Pascucci et al. 2000). The Horton Group is overstepped by the overlying
Windsor and Mabou groups, which also rest on pre-Carboniferous basement rocks 8
(Pascucci et al. 2000). The varied styles of superimposed basins have generated a composite depocentre in the Sydney Basin (Pascucci et al. 2000).
The sediment fill in the Magdalen Basin is thicker than in the Sydney Basin but contains equivalent stratigraphic units, and is characterized by extensive volcanic rocks in the central part of the basin and widespread evaporite rocks and associated salt tectonics
(e.g., Langdon and Hall 1994). The Cabot Strait area is located at the boundary between these two basins, and is characterized by structural complexity involving both salt tectonics and strike-slip faults (Langdon and Hall 1994). Under the strait, two linear graben parallel major fault trends and preserve up to 6 km of Devonian-Carboniferous sedimentary rocks, as described in more detail in Chapter 2.
The Bay St. George sub-basin is part of the Magdalen Basin (Fig. 1.5), and contains a thick sequence of Carboniferous rocks (Codroy and Barachois groups) in faulted contact at the St. George’s Bay Fault with the onshore section (Langdon and Hall
1994). The potential correlation of this fault and others in the Cabot Strait with specific faults in Cape Breton Island remains speculative (Langdon and Hall 1994).
1.4 Previous Geophysical Work
Loncarevic et al. (1989) compiled and interpreted available magnetic and gravity data for Cape Breton Island, southwestern Newfoundland, and the intervening offshore area, and proposed broad correlations between tectonostratigraphic zones in Cape Breton
Island and southwestern Newfoundland. They also used deep seismic reflection lines 86-
5A and 5B, recorded through the area in 1986 as part of the Canadian Lithoprobe and
Frontier Geoscience programs (Marillier et al. 1989). Loncarevic et al. (1989) showed that both the Cape Breton Highlands and southwestern Newfoundland are characterized 9 by distinctive magnetic and gravity anomaly patterns that can be traced offshore into the
Cabot Strait, but connections between the two areas are equivocal. Loncarevic et al.
(1989) correlated the Bras d’Or terrane with the Hermitage Flexure area in
Newfoundland, the Aspy terrane with the area between the Cape Ray and Bay d’Est faults, and the Blair River Inlier with Grenvillian basement in the Humber zone. They interpreted evidence for a seismic break on Line 86-5A as the boundary between the
Aspy and Bras d’Or terranes, with south-dipping reflectors suggesting that the Bras d’Or terrane is underlain by the Aspy Terrane, consistent with the overthrusting model of Barr et al. (1995, 1998).
Langdon and Hall (1994) used industry reflection seismic data to identify several major strike slip faults in the Cabot Strait and St. Georges Bay area. According to
Langdon and Hall (1994) the Cabot Fault was a master fault along which most of the strike-slip displacement occurred during late Carboniferous deformation of the sedimentary fill in the Magdalen and Sydney basins. They interpreted St. Paul Island to be located on a restraining bend along the Cabot fault.
Williams and Grant (1998) compiled offshore and onshore data to make a map showing thickness of Mesozoic and Carboniferous basins (Fig. 1.5). The Magdalen
Basin contains more than 12 km of Carboniferous rocks, including evaporites (Windsor
Group).
Williams et al. (1999) provided an overview of magnetic and gravity characteristics of the geological terranes of Newfoundland and Nova Scotia. These data provide a regional framework for the more detailed investigations of the present study.
Ethier (2001) compiled geological and geophysical data for northern Cape Breton
Island and used these data to revise the existing geological map by Barr et al. (1992). 10
Pascucci et al. (1999, 2000) compiled and interpreted industry seismic data in the
Sydney Basin area, together with data from two offshore wells in the area and deep reflection profile line 86-5. They identified major faults in the offshore and postulated correlations with onshore faults. They also recognized positive flower structures associated with the faults which deformed upper Paleozoic strata in the basin, and experienced several phases of reactivation into the Permian.
Using magnetic and gravity map patterns and measured petrophysical data, King
(2002) showed systematic contrasts in physical properties and measured responses between the Mira and Bras d’Or terranes in Cape Breton Island. He modeled the terrane boundary as sub-vertical at surface and shallowing to a dip of 50-70o northwest at depth.
He correlated the boundary with the McIntosh Brook-Georges River fault onshore (Fig.
1.3). Magnetic and gravity map patterns and models indicate that the original terrane boundary has been cut and offset by other faults, consistent with a dynamic post-
Devonian tectonic history (e.g., Pascucci et al. 2000).
1.5 Methods
1.5.1 Geophysical Data and Modeling
Magnetic and gravity data for the study area and surrounding areas were obtained from the Geological Survey of Canada. Data were regridded and new maps produced to bring all data to the same projection and allow for digital analysis and processing.
Processing of the magnetic and gravity data were accomplished using UNIX-based GMT software (Smith and Wessel 1991), version 4.5.7 released July 15th, 2011. The magnetic data were regridded at a spacing of about 500 m and a new total magnetic field (TMF) anomaly map was generated. The regridded data were used to calculate the 1st and 2nd 11 vertical derivative maps, and a map displaying downward continuation of the data to 400 m. The gravity data compilation consisted of Bouguer-corrected data for the onshore and free-air corrected data for the offshore. The gravity data were regridded at a spacing of about 2 km and a new gravity anomaly map was made. The regridded data were also used to make a map showing the horizontal gradient of the gravity field. More details about the methodology are provided in Chapter 3.
Based on previous work in the area, mainly by Loncarevic et al. (1989), Langdon and Hall (1994), and Pascucci et al. (2000), and the new geophysical maps compiled during the present study, locations were selected for 6 models: two models across the offshore magnetic anomaly near northern Cape Breton Island (Fig. 1.1) to interpret the cause of this anomaly; three other models across the Cabot Strait to help understand how the geology of Cape Breton Island correlates to southwestern Newfoundland; and one model to represent the subsurface geology of the Bay St. George sub-basin. The forward modeling was completed using GM-SYS (Pro)® 4.8 2D modeling software (Wessel and
Smith 2012). The geophysical models were constrained using geological information and seismic reflection profile interpretations obtained from published papers and reports, and by physical property information described below.
1.5.2 Physical Property Data
In order to provide additional constraints on the models, magnetic susceptibility was measured in about 2800 samples from the eastern Cape Breton Highlands. These samples were collected by S. Barr, her colleagues, and students between 1978 and 2010 and are archived in the Department of Earth and Environmental Science at Acadia
University. The accompanying database for these samples includes rock types and UTM 12 coordinates. Most of the samples are cut slabs. Susceptibility measurements were made using a hand-held KT-9 Kappameter manufactured by Exploranium Radiation Detection
Systems. Typically three measurements were made on each slab, and the results averaged. No samples are available from rock units in southwestern Newfoundland so typical values from published papers and lithologically similar rocks in Cape Breton
Island were used in the models for units in that area.
For gravity modeling, density values were assumed using data for similar rocks types from the compilation by Tenzer et al. (2011), as well as measured data from the work of King (2002). The methods and sources of the data covered in this study are described in more detail in Chapter 3. 13
Fig. 1.1 Total field magnetic anomaly map of Cape Breton Island, southwestern Newfoundland and adjacent areas from Oakey and Dehler (1998) showing the location of the study area. The small black box inside the study area indicates the location of the circular anomaly east of Cape Breton Island noted in the text. White areas indicate lack of data.
14
Fig. 1.2 Bathymetric map of the area between Cape Breton Island and southwestern Newfoundland from Oakey (1999).
15
Fig.1.3 Map of part of the northern Appalachian orogen showing major geological components (modified from Lin et al. 2007). The study area is outlined in red. Inset map on lower right shows terranes in Cape Breton Island in more detail. Abbreviations: A, Aspy terrane; B, Bras d’Or terrane; BEF, Bay d’Est Fault; BRI, Blair River Inlier; CF, Cabot (Long Range) fault, CRF, Cape Ray Fault, DHBF, Dover - Hermitage Bay Fault, ESZ, Exploits subzone; GZ, Gander Zone; HF, Hermitage Flexure area; M, Mira terrane (Avalonia); NDS, Notre Dame subzone; RIL, Red Indian Line.
16
Fig. 1.4 Simplified geological map showing rock units in the Aspy and Bras d’Or terranes (modified from Lin et al. 2007). Lettered units are as follows: a, Money Point Group; b, Cape North Group; c, Cheticamp Lake Gneiss; d, Clyburn Brook Formation; e, Cameron Brook pluton; f, Black Brook Granitic Suite; g, Neils Harbour Gneiss. Abbreviations: EHSZ, Eastern Highlands Shear Zone (Aspy- Bras d’Or terrane boundary); MB/GRF, MacIntosh Brook/Georges River Fault (Bras d’Or-Mira terrane boundary); RRF/WBF, Red River Fault/Wilkie Brook Fault (Blair River Inlier-Aspy terrane boundary).
17
Fig. 1.5 Map of the Cabot Strait and surrounding area showing depth to pre-Mesozoic (shades of yellow), pre-Carboniferous (shades of blue; depth colour represented at 2 km intervals), and pre-Paleozoic (shades of green) basement (modified from Williams and Grant 1998).The Sydney and Magdalen basins are both part of the Maritimes Basin (Gibling et al. 1987). Also shown are major tectonostratigraphic subdivisions in southwestern Newfoundland (as described in the text), and distribution of Silurian-Devonian, Neoproterozoic, and Mesoproterozoic rocks in Cape Breton Island. Legend is shown in Figure 1.6.
18
Fig. 1.6 Legend for the map in Figure 1.5 (modified from Williams and Grant 1998). 19
2.0 GEOLOGICAL SETTING
2.1 Introduction
This chapter provides more detailed background information about rock units onshore in eastern Cape Breton Island (Fig. 2.1) and southwestern Newfoundland (Fig.
2.2a, b). Pre-Carboniferous units in these areas are described below by terrane, followed by Carboniferous units, first in Cape Breton Island and then in Newfoundland. The geology of the intervening offshore area is then described.
As noted in Chapter 1, previous workers, most recently Lin et al. (2007), have speculated on pre-Carboniferous unit correlations between Cape Breton Island and
Newfoundland, but the relations remain equivocal because of thick Carboniferous cover in the offshore and geological and structural complexity both onshore and offshore.
2.2 Bras d’Or Terrane
2.2.1 Introduction
The Bras d’Or terrane consists low-pressure cordierite-andalusite (or sillimanite) gneiss (Bras d’Or Gneiss), low- to high-grade metasedimentary and minor metavolcanic rocks (George River Metamorphic Suite), an abundance of mafic to felsic plutonic rocks of mainly ca. 565-555 Ma and ca. 500 Ma ages, and minor Cambrian-Ordovician sedimentary and volcanic rocks (e.g., Raeside and Barr 1990; White et al. 1994). The protolith rock types of the various components in the George River Metamorphic Suite and Bras d’Or Gneiss are similar and include pelitic, psammitic and carbonate rocks, but they differ in relative abundance (Raeside 1989, 1990; Raeside and Barr 1990). The absolute ages of the metamorphic units in the Bras d’Or terrane are not well constrained, 20
but their minimum age is late Neoproterozoic, based on the ages of cross-cutting plutonic rocks. The 565-555 Ma plutons are composed of diorite, tonalite, granodiorite and granite with petrological characteristics indicating that they formed in a continental margin subduction zone (Farrow and Barr 1992). The 500 Ma plutons are of granitic composition and formed during localized extension within the terrane (White et al. 1994).
The boundary between the Bras d’Or terrane and the Aspy terrane is interpreted to be the Eastern Highlands shear zone, a mylonitic fault zone with a protracted and complex history (e.g., Raeside and Barr 1992; Lin 1993, 1995; Lin et al. 1994; Barr et al.
1995, 1998). The zone is composed of mylonite, blastomylonite, and chlorite schist and ranges in width from 200 to 1300 m (Raeside and Barr 1992). Yaowanoiyothin and Barr
(1991) suggested that the Black Brook Granitic Suite is a “stitching pluton” and that the
Aspy – Bras d’Or terrane boundary originally extended through the Black Brook Granitic
Suite (Fig. 2.1). They based this interpretation on differences in xenolithic material between western and eastern parts of the suite and also on the presence of a belt of strongly foliated granitic rocks through the central part of the plutonic suite. They suggested that the Black Brook Granitic Suite intruded into the active shear zone at the terrane boundary, which then stepped to the south, forming splays that extend north and south of the Cameron Brook pluton and which continued to be active into the
Carboniferous. Hence units in that area, including the Clyburn Brook Formation, Neils
Harbour Gneiss, Cameron Brook pluton, and Ingonish Island Rhyolite, are enigmatic in terms of whether they are part of the Aspy or Bras d’Or terrane. However, because of their overall similarity to Aspy terrane units, they are described with the Aspy terrane below, rather than with Bras d’Or terrane. 21
Metamorphic and plutonic rocks in the Bras d’Or terrane formed at a wide range of crustal depths from shallow in the south to deep (as much as 25 km) near the Eastern
Highlands shear zone (Barr et al. 1995; Farrow and Barr 1992). The variation in depth of exposure is consistent with a model that involves thrusting of Bras d’Or terrane over
Aspy terrane and implies that the terrane boundary dips to the south (Barr et al. 1995).
The southern boundary of the Bras d’Or terrane is placed at the MacIntosh Brook-
George River fault, an early Carboniferous fault which cannot be traced across upper
Carboniferous units (e.g., Pascucci et al. 2000). The terrane boundary is placed at this fault because of contrasts in Neoproterozoic rock units northwest (Bras d’Or terrane) and southeast (Mira terrane) of the fault; however, it is recognized that the fault is a
Carboniferous feature and not the actual terrane boundary (e.g., Barr et al. 1995). Based on potential field modeling, the terrane boundary is approximately at that location and dips to the northwest (King 2002).
2.2.2 Bras d’Or Gneiss
Two components of the Bras d’Or Gneiss occur in the eastern part of Cape Breton
Island, the Kellys Mountain Gneiss and the Frenchvale Road Metamorphic Suite (Fig.
2.1). The Kellys Mountain Gneiss is composed of migmatitic paragneiss with dominating assemblages bearing biotite, and biotite-cordierite (Jamieson 1984).
Subordinate rock types include cordierite-sillimanite (andalusite) gneiss, amphibolite, and calc-silicate rocks (Raeside and Barr 1990). The level of migmatization increases towards the centre of gneiss, away from the exposed contacts with the Kellys Mountain Granite and associated diorite (Raeside and Barr 1990; Barr et al. 1990). Metamorphism of the 22
Kellys Mountain Gneiss was dated using U-Pb (titanite) at 496 ± 5 Ma, the same age as the surrounding Kellys Mountain Granite (Dunning et al. 1990a), but the protolith age of the gneiss is unknown.
The Frenchvale Road Metamorphic Suite is located on the southeastern margin of the Bras d’Or terrane adjacent to the MacIntosh Brook – George River Fault, but no evidence of deformation related to the fault has been found in the gneiss (Raeside 1989).
The dominant rock types are marble and calc-silicate rocks, particularly in the northern area of the suite; other components are quartzite and feldspathic quartzite (Raeside and
Barr 1990). The lack of minerals to indicate metamorphic grade resulted in the unit previously being assigned to the low-grade George River Group (Milligan 1970).
However, the calc-silicate rocks are interlayered with thin semipelitic and pelitic layers, preserved as andalusite-biotite schist, cordierite-biotite gneiss, and sillimanite-biotite gneiss, and hence Raeside and Barr (1990) assigned the unit to the Bras d’Or Gneiss rather than the George River Metamorphic Suite.
2.2.3 George River Metamorphic Suite
Historically, most pre-Middle Devonian stratified units in central and northern
Cape Breton Island, including the Bras d’Or Gneiss, were assigned to the George River
Series or Group, particularly if they contain carbonate-bearing sequences (e.g., Milligan
1970; Keppie 1979). More recently, in recognition of the fact that these units vary in rock type and metamorphic grade, and correlation among them cannot be proven, local names have been applied and together they are termed the George River Metamorphic
Suite instead of group (Raeside and Barr 1990; Keppie 2000). The components of the 23
George River Metamorphic Suite which occur in the eastern part of Cape Breton Island
(Fig. 2.1) are described here. In addition to the major units mentioned below, smaller areas of these rocks occur in faulted slivers along the southeastern margin of the Kellys
Mountain Granite (Fig. 2.1).
The Benacadie Brook Formation (Fig. 2.1) of the western Boisdale Hills consists of bedded to massive metasiltstone, quartzite, marble, and minor mafic volcanic rocks
(Raeside 1989). Regional metamorphic grade throughout the area is in the lower greenschist facies, with biotite and cordierite occurring only near contacts with plutons.
The McMillan Flowage Formation is the largest, most continuous, and most compositionally variable stratified unit in the Bras d’Or terrane (Raeside and Barr 1992).
The formation terminates to the north against the Eastern Highland Shear Zone and extends to the south for 50 km where it is overlain unconformably by Carboniferous units
(Raeside and Barr 1992). Raeside and Barr (1992) divided the McMillan Flowage
Formation into five members. The lowermost member is composed of quartzite, semipelitic phyllite, and black slate, grading upward into garnet phyllite interbedded with psammite. The overlying member is composed predominantly of quartzite with some arkosic or psammitic varieties. It is overlain by the middle member, composed of a lower pelitic and semipelitic part containing thin amphibolite and calc-silicate lithologies, a middle part composed of quartzite and amphibolite, and an upper part composed of semipelitic schist with fewer quartzite and amphibolite layers. The overlying marble member is composed of 25-35 m of marble and calc-silicate with 1-2 m layers of amphibolite, overlain by a 25-75 m layer of quartzite and feldspathic quartzite. The 24
uppermost member is 500 m thick and composed of quartzite, feldspathic quartzite, and semipelite, with thin lensoid amphibolite in its upper part (Raeside and Barr 1992).
The Barachois River Metamorphic Suite is represented by two blocks of gneissic rocks enclosed by the Indian Brook Granodiorite, Ingonish River Tonalite, and Timber
Lake Diorite, and areas of metasedimentary rocks in the Big Hill and Kellys Mountain area (Fig. 2.1). A small area of gneissic rocks west of Middle Head termed the Ingonish
Beach Gneiss may be part of the same unit, based on its location between the Ingonish
River Tonalite and Wreck Cove Dioritic Suite (Fig. 2.1). The gneissic rocks contain K- feldspar augen with flaggy semipelitic and mafic gneiss interlayers (Raeside and Barr
1992). Farther south, the unit becomes more sedimentary in appearance as the metamorphic grade decreases and the units are dominated by grey metawacke which make up most of the Big Hill and Kellys Mountain metasedimentary blocks.
The Price Point Formation is a subgreenschist-facies volcanic unit restricted to the southeastern Cape Breton Highlands where it occurs mainly in graben-like structures in the Indian Brook Granodiorite and associated plutons (Fig. 2.1). It consists of calc-alkalic andesitic to dacitic rocks (Macdonald and Barr 1985; Grecco and Barr 1999). Based on contact relations, it is assumed to be similar in age to and co-magmatic with the surrounding ca. 560 Ma plutons (Macdonald and Barr 1985).
2.2.4 Ca. 565-555 Ma Plutonic Units
The ca. 565-555 Ma plutonic units in the eastern part of the Bras d’Or terrane are described according to dominant rock type, beginning with mafic-intermediate plutons and then intermediate-felsic plutons. 25
2.2.4.1 Mafic to intermediate plutons
The Gisborne Flowage Quartz Diorite intruded the McMillan Flowage Formation and has a U-Pb (zircon) igneous crystallization age of 564 ± 2 Ma, with titanite yielding a somewhat younger cooling age of 548 ± 2 Ma (Dunning et al. 1990a). In comparison to other plutons in the area, the Gisborne Flowage Quartz Diorite has a greater abundance of biotite, as well as streaks, layers, and patches of mafic (amphibolitic) composition
(Raeside and Barr 1992). It has been intruded by dykes and small bodies of granitic pegmatite and grey foliated granodiorite with medium to fine grey size (Raeside and Barr
1992).
The Wreck Cove Dioritic Suite is composed mainly of medium-grained quartz diorite, but grades to diorite and granodiorite. Grain size varies from fine to coarse to pegmatoid (Raeside and Barr 1992). Pegmatoid hornblende yielded a 40Ar/39Ar age of about 560 Ma, a minimum age for the diorite (Reynolds et al. 1989). The pluton is intruded by the Ingonish River Tonalite, as evidenced by the presence of dioritic xenoliths in the tonalite near the contact (Raeside and Barr 1992), and by granite and granodiorite of the Cape Smokey, Birch Plain and Indian Brook plutons (Raeside and
Barr 1992). In addition to the main body of the pluton, dioritic rocks on the Middle Head
Peninsula (Fig. 2.1) are also considered to be part of the Wreck Cove Dioritic Suite
(Raeside and Barr 1992).
The Kathy Road Dioritic Suite is the most extensive dioritic intrusion in the Cape
Breton Highlands, elongate in a north-south direction parallel to the boundary with the
Aspy terrane to the west (Raeside and Barr 1992). Strong foliations are visible near its western margin in the Eastern Highlands shear zone. Medium-grained quartz diorite is 26
the most abundant rock type, and more mafic diorite and leucocratic tonalite varieties also occur, with grain size ranging from fine to coarse (Raeside and Barr 1992). The presence of epidote of magmatic origin suggests relatively high pressure of crystallization, consistent with the high Al-amphibole composition (Farrow and Barr
1992). The U-Pb (zircon) age is 560 ± 2 Ma (Dunning et al. 1990a).
The Timber Lake Dioritic Suite is composed of rocks similar to those of the
Kathy Road Dioritic Suite, although the McMillan Flowage separates the two units, and is assumed to be related and of similar ca. 560 Ma age (Raeside and Barr 1992).
Composition varies from quartz diorite to diorite.
The Ingonish River Tonalite is a large intrusion extending from the Ingonish area south to the Barachois River area (Raeside and Barr 1992). The age of the tonalite is 555
± 2 Ma, based on U-Pb (zircon) dating (Dunning et al. 1990a).
The Kellys Mountain Diorite occurs mainly in the southern part of the Kellys
Mountain peninsula and along its western edge. It is typically a composite unit which includes granodioritic and granitic rocks (Barr et al. 1982). The unit is undated but assumed to have an age of ca. 560 Ma like other dioritic plutons in Bras d’Or terrane
(Raeside and Barr 1990).
In addition to these large dioritic and tonalitic plutons, small bodies composed of similar rocks are scattered through the area and are assumed to be related and of similar age.
2.2.4.2 Intermediate to felsic plutons
The Indian Brook Granodiorite is the largest intermediate to felsic pluton in eastern Cape Breton Island. It is medium- to coarse-grained biotite-hornblende 27
granodiorite composed of plagioclase, microcline, quartz, hornblende and biotite, with accessory titanite, zircon, and magnetite. The U-Pb (zircon) age of about 575 to 572 Ma contains evidence of inheritance, and the U-Pb (titanite) age of 564 ± 5 Ma is assumed to better indicate the igneous crystallization age (Dunning et al. 1990a). Smaller granodioritic bodies of similar composition in the St. Anns area, described in detail by
Grecco and Barr (1999), are also grouped with the Indian Brook Granodiorite for the purposes of this study.
The Birch Plain Granite is undated but appears to have been intruded by the
Indian Brook Granodiorite and hence may be older (Raeside and Barr 1992). Minerals present are plagioclase, microcline, quartz, and up to 10% biotite, with accessory allanite, zircon, titanite, apatite, and magnetite. The Birch Plain Granite contains weak to moderate foliation defined by biotite alignment (Raeside and Barr 1992).
The Cross Mountain Pluton and Bell Lakes Plutonic Suite differ from the other plutons of the Bras d’Or terrane as they consist of granodioritic and tonalitic rocks which contain muscovite and lack amphibole. Both are fine to medium grained and weakly foliated (Raeside and Barr 1992). Plagioclase and quartz are the most abundant felsic minerals, with varying amounts of K-feldspar (Raeside and Barr 1992). A garnet-bearing muscovite-biotite granodiorite sample from the Bell Lakes Plutonic Suite yielded an age of 556 ± 4 Ma, similar to the ages of amphibole-bearing plutons in the area.
The Shunacadie Pluton is located in the western part of the Boisdale Hills and intruded the Benacadie Brook Formation. Granodiorite forms almost all of the pluton
(Barr and Setter 1986) and yielded a U-Pb (zircon) age of 564 +3/-2 Ma (Dunning et al.
1990a). The nearby Boisdale Hills Pluton is a composite suite of plutonic rocks 28
including diorite, hornblende granodiorite, biotite-hornblende granodiorite, and biotite granodiorite, but dominated by granodiorite (Barr and Setter 1986). Its age is not well constrained by U-Pb dating, but it is assumed to be of similar age to the Shunacadie
Granodiorite.
2.2.5 Ca. 500 Ma Plutonic Units
The Cape Smokey Granite is a large pluton in the Cape Smokey area. U-Pb dating of zircon yielded a Late Cambrian age of 493 +1/-2 Ma (Dunning et al. 1990a).
The Cape Smokey Granite consists of pink to red, medium- to coarse-grained leucogranite, with equal abundance of plagioclase, orthoclase, and quartz. The unit contains only 1 to 2 % biotite, which is almost completely altered to chlorite (Raeside and
Barr 1992). The Cape Smokey Granite also occurs as sheets and small bodies in dioritic rocks on Middle Head, and forms a small body east of the Cameron Brook pluton at Red
Head (Fig. 2.1). The latter occurrence is significant because it ties this area to the Bras d’Or terrane in the early Cambrian, and supports the interpretation of Lin et al. (2007) that Aspy terrane rocks were deposited on Bras d’Or terrane units.
The Kellys Mountain Granite is composed of the same leucogranite as the Cape
Smokey Granite, as well as minor biotite granite and granodiorite (Barr et al. 1982). The leucogranite is a medium- to coarse-grained and composed of plagioclase (albite- oligoclase), perthitic orthoclase, and quartz, with very minor mafic minerals (1-2 % chloritized biotite) (Raeside and Barr 1992). The U-Pb (zircon) age is 498 ± 2 Ma (Barr et al. 1990). Similar leucogranite forms large bodies in the St. Anns area where it intruded granodioritic rocks and the Price Point Formation (Fig. 2.1). 29
The Mount Cameron Syenogranite is in the northern part of the Bourinot belt in the Boisdale Hills. It consists of plagioclase and quartz phenocrysts in a granophyric groundmass. It has yielded a U-Pb (zircon) age of 509 ± 2 Ma, similar to the age of rhyolite in the Bourinot Group with which it is interpreted to be comagmatic based on similar age and petrology (White et al. 1994; Palacios et al. 2012).
2.2.6 Bourinot Belt
The Bourinot belt (Fig. 2.1.) is a narrow fault-bounded, northeast-trending belt 30 km long and 3 km at its maximum width. It occupies a valley between ridges of older metamorphic and plutonic units, and is composed of Cambrian and Lower Ordovician volcanic and sedimentary rocks (White et al. 1994; Palacios et al. 2012).
2.3 Aspy Terrane
2.3.1 Introduction
The Aspy terrane underlies most of western and central Cape Breton Highlands
(Fig. 1.2). It is characterized by metamorphosed Ordovician and Silurian sedimentary and volcanic rocks affected by Devonian thermal events and granitic magmatism, but also includes Neoproterozoic rocks in the western highlands with similarities to Bras d’Or terrane units (Raeside and Barr 1992; Lin et al. 2007).
One of the most prominent faults in Cape Breton Island, the Aspy Fault, occurs within the Aspy terrane. Most of the fault is overlain by alluvial and scree deposits; sheared rocks exposed in the North Aspy River show brittle fracturing with abundant quartz or calcite veining (Raeside and Barr, 1992). The Aspy fault has remobilized 30
gypsum and limestone of the Windsor Group, and the Margaree Pluton has been cut by the fault indicating an age of movement in the post-Late Devonian to Early Mississippian
(Raeside and Barr 1992).
The boundary of the Aspy terrane with the Blair River Inlier is located north of the Aspy Fault at the Wilkie Brook fault zone. In the west, the Red River fault separates the Aspy terrane from the Blair River Inlier. The zone of confluence of the two faults is cut by Devonian granite (Margaree Pluton; Fig. 2.1). Both fault zones contain chloritized mica schist preserving porphyroclasts with strong cataclastic textures (Raeside and Barr
1992). Fault movement likely occurred during the amphibolite-granulite facies metamorphism of the Polletts Cove River Group, and during the greenschist facies retrograde metamorphism, which affected the Blair River Inlier and the Aspy terrane mylonite in the fault zones (Raeside and Barr 1992). Late brittle movement during the
Carboniferous and younger periods is indicated by kink-band structures (Raeside and
Barr 1992).
2.3.2 Cape North Group
The Cape North Group consists of semipelitic, pelitic, and calc-silicate gneiss, with small quantities of amphibolite and marble (Macdonald and Smith 1980; Raeside and Barr 1992). The age is not well constrained, except it is older than a diorite body near Money Point which yielded a U-Pb (zircon) age of 424 ± 5 Ma (Lin et al. 2007). It is uncertain whether the Cape North Group is older or younger than the Money Point
Group, or its higher grade correlative (Lin et al. 2007).
31
2.3.3 Money Point Group
The Money Point Group is more extensive than the Cape North Group (Fig. 2.1).
It consists of both metavolcanic rocks (metabasalt, metatuff and metarhyolite) and metasedimentary rocks (pelite, semipelite, calc-silicate rocks, and rare marble). A rhyolite sample yielded a U-Pb zircon age of 427.5 ± 2 Ma (Keppie et al. 1992). Various areas assigned to the unit are separated from one another by faults and/or granitic and orthogneiss bodies (Raeside and Barr 1992). The areas of the Money Point Group to the south of the Aspy Fault are compositionally similar to the rocks in the north (from where the dated sample was collected) but have been metamorphosed at medium to high grades
(Raeside and Barr 1992). Geochemical characteristics of volcanic rocks in the Money
Point Group indicate that these rocks formed in a volcanic-arc setting (Barr and Jamieson
1991).
Farther to the southwest in the Aspy terrane, the Sarach Brook Metamorphic Suite
(Fig. 2.1) is considered to be correlative with the Money Point Group (Barr and Jamieson
1991). It consists of metasedimentary and interlayered metabasic rocks in the west and felsic crystal-lithic tuff, epiclastic volcanogenic sedimentary rocks, and minor flow- banded rhyolite in the structurally higher eastern part. Rhyolitic crystal tuff near the structural top of the suite has yielded a U-Pb (zircon) crystallization age of 433 ± 2 Ma
(Dunning et al. 1990a).
2.3.4 Clyburn Brook Formation
The Clyburn Brook Formation includes mafic and felsic flows and tuffs, interlayered with less abundant semi-pelitic metasedimentary rocks (Barr and Raeside 32
1998). These rocks are located in the boundary zone between the Bras d’Or and Aspy terranes (Barr and Raeside 1998). Petrochemical characteristics of mafic rocks in the
Clyburn Brook formation indicate tholeiitic affinity and origin in an arc-related setting, possibly a back-arc. Felsic rocks also have compositions consistent with an extensional setting, possibly a continental arc or back. Overall, the Clyburn Brook formation shows lithological and chemical similarity to the Money Point Group, and is inferred to be of similar Silurian age.
2.3.5 Cheticamp Lake Gneiss
The Cheticamp Lake Gneiss occurs in the central part of the Aspy terrane (Fig.
2.1). The most common rock types are semipelitic gneiss, biotite schist, and massive quartzofeldspathic gneiss (Raeside and Barr 1992). The age of deposition of the sedimentary protolith of the gneiss is unknown. A U-Pb (zircon) age of 396 ± 2 Ma is interpreted to indicate the time of high-grade metamorphism and migmatization (Dunning et al. 1990a).
2.3.6 Glasgow Brook Orthogneiss
The Glasgow Brook orthogneiss is composed of foliated medium- to coarse- grained hornblende-biotite tonalite to granodiorite (Raeside and Barr 1992). The rock is gneissic in appearance, with alternating feldspathic and mafic mineral layers defining the foliations. The pluton intrudes schist of the Money Point Group on the north, and a narrow band of mica schist of the Cheticamp Lake Gneiss separates it from the Black 33
Brook Granite Suite (Raeside and Barr 1992). It contains abundant dioritic and semipelitic xenoliths (Raeside and Barr 1992).
2.3.7 Cameron Brook Granodiorite
The Cameron Brook Granodiorite intruded the Clyburn Brook Formation and possibly Ingonish River Tonalite. It consists mainly of coarse-grained, variably megacrystic granodiorite (Raeside and Barr 1992). The megacrysts are composed of perthitic K-feldspar and plagioclase. The dominant mafic mineral is biotite, locally accompanied by subordinate amphibole (Raeside and Barr 1992). A mid-Devonian U-Pb
(zircon) age of 402 ± 3 Ma was obtained for the pluton (Dunning et al. 1990a).
2.3.8 Neils Harbour Gneiss
The Neils Harbour Gneiss is located along the eastern margin of the Black Brook
Granitic Suite which intruded it (Yaowanoiyothin and Barr 1991). It is composed of heterogeneous gneissic rocks, predominantly orthogneiss with some local biotite schist
(Raeside and Barr 1992). The orthogneiss is typically granodioritic with porphyroblasts and megacrysts of microcline. U-Pb dating of zircon from the megacryst orthogneiss gave an age of 403 ± 3 Ma, which is inferred to be the igneous crystallization age of the igneous protolith (Dunning et al. 1990a). Given the similarity in age and petrology, the orthogneiss is likely to be the deformed equivalent of the Cameron Brook Granodiorite.
34
2.3.9 Ingonish Island Rhyolite
On Ingonish Island (Fig. 2.1), flow-banded rhyolite is unconformably overlain by the Windsor Group. The rhyolite is mostly dark brown to black, with sparse phenocrysts of alkali feldspar and quartz (Raeside and Barr 1992). Finely disseminated magnetite causes the dark coloration of the felsic volcanic rocks (Raeside and Barr 1992). The volcanic flows contain cryptocrystalline to microcrystalline quartz and potassium feldspar, with phenocrysts of euhedral and subhedral anorthoclase (Raeside and Barr
1992). The flows are interbedded with pyroclastic flows composed of sparse crystal and lithic fragments in recrystallized tuffaceous matrix of quartz, alkali feldspar, magnetite, and sericite (Raeside and Barr 1992). The rhyolite is cut across by fine-grained granitic dykes which appear similar to the Black Brook Granitic Suite. Preliminary results of U-
Pb dating of zircon indicated an age of ca. 400 Ma (G. Dunning, personal communication to S. Barr, 2010).
2.3.10 Black Brook Granitic Suite
The Black Brook Granitic Suite is composed of three units, two different monzogranitic units and a granodiorite unit. All three units contain muscovite and biotite, and are peraluminous (Yaowanoiyothin and Barr 1991; Raeside and Barr 1992). U-Pb dating of monzonite from the Black Brook Granitic Suite yielded an age of 375 +7/-2 Ma, interpreted to be the igneous crystallization age of the pluton (Dunning et al. 1990a).
Several other granitic and orthogneissic units in the eastern Aspy terrane appear similar in mineralogy to the Black Brook Granitic Suite and are likely part of the same igneous event. They include the Park Spur Granite and Middle Aspy River Orthogneiss 35
(Fig. 2.1). Similar fine- to medium-grained foliated muscovite-biotite granite plutons, sheets and dykes occur in the Money Point and Cape North groups north of the Aspy
Fault (Macdonald and Smith 1980).
These widespread granite plutons likely formed during collision between the Bras d’Or and Aspy terranes.
2.3.11 Wilkie Sugarloaf and Similar Granite Plutons
Wilkie Sugarloaf Granite is the largest of several similar granite plutons that occur near the Aspy Fault. The plutons are composed of coarse-grained monzogranite containing oligoclase, microcline, quartz, and biotite, and all are likely of Devonian age.
They may be related to the Margaree Pluton in the western part of the terrane.
2.3.12 Fisset Brook Formation
Late Devonian sedimentary and bimodal volcanic sequences occur in scattered fault-bounded basins in western Cape Breton Island, where they are termed the Fisset
Brook Formation (Kelley and Mackasey 1965; Dunning et al. 2002). The rhyolite units have yielded ages of ca. 375 Ma throughout the terrane (Dunning et al. 2002), and hence are likely cogenetic with granitic plutons of similar Late Devonian age and within-plate petrological characteristics, such as Margaree and Wilkie Sugarloaf.
2.4 Blair River Inlier
2.4.1 Mesoproterozoic Rocks 36
The Blair River Inlier forms the northwestern tip of Cape Breton Island, in faulted contact along the Red River and Wilkie Brook shear zones with rocks of the Aspy terrane
(Fig. 2.1). It consists mainly of several composite orthogneissic units, intruded by less deformed plutons of varied compositions including anorthosite, gabbro, syenite, and granite. Miller et al. (1996) and Miller and Barr (2000) reported U-Pb dates confirming that major units in the inlier are of Mesoproterozoic age, including the Sailor Brook gneiss (>1217 Ma), Lowland Brook Syenite (1080 +5/-3 Ma), Red River Anorthosite
Suite (>1095 Ma), and Otter Brook gneiss (978 +6/-5 Ma). They also showed that high- grade metamorphism of the Sailor Brook gneiss occurred at 1035 +12/-10 Ma, and that the Red River Anorthosite Suite was metamorphosed at 996+6/-5 Ma.
Paleozoic igneous activity in the Blair River inlier is demonstrated by the 435
+7/-3 Ma age from a small granitic unit. In addition, Paleozoic amphibolite-facies metamorphism is reflected in ca. 425 Ma titanite ages from the Proterozoic units, and subsequent cooling through hornblende, muscovite, and phlogopite 40Ar/39Ar, and rutile
U-Pb, closure temperatures lasted until ca. 410 Ma (Miller et al. 1996).
No record of Cambrian-Ordovician passive margin sedimentary sequences is preserved in the Blair River Inlier, unlike in the Humber Zone of Western Newfoundland
(Barr et al. 1998). The absence of a cover sequence may be the result of the Blair River
Inlier being situated on the Laurentian promontory during Silurian orogenesis, cover rocks were most likely eroded or removed during uplift (Barr et al. 1998).
The Polletts Cove River Group (Fig. 2.1) includes all of the stratified rocks of the
Blair River Inlier, composed mainly of quartzofeldspathic gneiss, amphibolite and amphibolite gneiss, and metagabbro, with minor amount of calc-silicate rocks and 37
granulite (Raeside and Barr 1992). The quartzofeldspathic gneiss shows the most layering, in part attributed to relict bedding but in most cases caused by the variation in mafic minerals caused by metamorphism (Raeside and Barr 1992).
The Lowland Brook Syenite is the largest intrusion in the Blair River Inlier
(Raeside and Barr 1992). The syenite varies from massive to gneissic, generally red in colour, medium to coarse grained (Raeside and Barr 1992). It consists mainly of perthitic and antiperthitic alkali feldspar, with minor interstitial sodic plagioclase, amphibole and clinopyroxene (Raeside and Barr 1992).
Rock types and ages in the Blair River Inlier indicate that it is part of the
Grenville province of the Canadian Shield, like similar inliers in the Humber Zone in
Newfoundland (Barr et al. 1998). Its gneissic rocks are similar to those in the Indian
Head Inlier in the Humber Zone, and its anorthositic components are like those of the
Steel Mountain Inlier in the Humber Zone (Fig. 2.2a, b).
2.4.2 Lowland Cove Formation
The Lowland Cove Formation is a 400-m-thick sequence of rhyolite, clastic sedimentary and tuffaceous rocks, basalt, and andesite. The sedimentary components contain palynomorphs most recently interpreted as latest Famennian (Martel et al. 1993).
A rhyolite sample from this formation yielded an age of 365 ± 2 Ma, younger than the
Fisset Brook Formation elsewhere in western Cape Breton Island (Dunning et al. 2002), and hence the separate formation name is retained.
2.5 Carboniferous Units in Cape Breton Island 38
2.5.1 Horton Group
The latest Devonian (Famennian) to Tournaisian Horton Group unconformably
(in places conformably) overlies the Fisset Brook and Lowland Cove formations described above, as well as older units. It was deposited in a series of separate fault- bounded basins, mainly half-graben, with bounding faults oriented mainly east-west to northeast-southwest (Gibling et al. 2008). It is typically composed of thick conglomerate, shale, and sandstone successions deposited in alluvial fans, rivers, deltas, perennial lakes or brackish bays within rifted basins, and a topmost alluvial succession
(e.g., Hamblin and Rust 1989; Martel and Gibling 1996; Gibling et al. 2008).
2.5.2 Windsor Group
The Visean Windsor Group unconformably overlies the Horton Group, although the time gap between the two units is not large. The Windsor Group is composed of interstratified marine evaporite, marine carbonate and nonmarine siliciclastic rocks (e.g.,
Schenk et al. 1994; Boehner et al. 2003; Gibling et al. 2008). Evaporite accumulations are several hundreds of meters thick, the seafloor eventually becoming exposed in playa flats and during karstification (Schenk et al. 1994; Boehner 1986). The evaporite strata include sulfate and chlorite evaporites, with local potash and borate salts. Middle and upper
Windsor Group strata include thin fossiliferous marine carbonate rocks intercalated with redbeds. Total thickness of the Windsor Group is highly variable but can reach 1000 m in some areas, and even thicker in some places such as western Newfoundland and southern New Brunswick (Schenk 1969; Pascucci et al. 1999; Gibling et al. 2008).
39
2.5.3 Mabou Group
The late Visean-Namurian Mabou Group (previously known as the Canso Group;
Ryan et al. 1991) conformably overlies the Windsor Group, and consists of sandstone, siltstone, shale, limestone, and sulphate evaporates with some thick dark shale (Pascucci et al.1999; Gibling et al. 2008). The group can attain a thickness of 3000 m in Nova
Scotia.
2.5.4 Morien Group
The late Westphalian to Stephanian Morien Group (also known as the
Cumberland Group in other parts of the region; Pascucci et al. 1999) rests unconformably on the Mabou and Windsor groups (Pascucci et al. 1999). The basal part of the unit consists of braided-fluvial sandstones with minor coal. The upper part of the unit consists of sandstone, mudstone, economic coals, dark limestone, calcrete that were deposited in alluvial to restricted marine conditions (Pascucci et al. 1999).
2.5.5 Pictou Group
The Pictou Group was deposited during the Westphalian to Lower Permian, and is the youngest Paleozoic unit in the region. It consists mainly of continental red beds which were deposited across the Maritimes Basin during a period of regional thermal sag and aridity (Bell 1944; Ryan et al. 1991; Gibling et al. 2008). The red beds are composed of red sandstone and mudstone, reaching a thickness of 1650 m in the Cumberland Basin, and up to 3000 m in the Gulf of St. Lawrence (Ryan et al. 1991; van de Poll et al. 1995;
Pascucci et al. 1999). 40
2.6 Southwestern Newfoundland
2.6.1. Introduction
Lithotectonic zones in Newfoundland converge in the southwest in the western part of the area of transverse structures known as the Hermitage Flexure (Williams et al.
1988; Dunning and O’Brien 1989). This narrowing of the orogen has been attributed to promontory-promontory collision during closure of the Iapetus and Rheic oceans and the collision between composite Laurentia and the peri-Gondwanan fragments during the
Silurian and Devonian (Williams et al. 1988; Dunning et al. 1990b; Lin et al. 1994; van
Staal et al. 2009). The Red Indian Line (Fig. 2.2a) represents the suture between the peri-
Laurentian and peri-Gondwanan elements in central and northern Newfoundland, and merges with the Cape Ray Fault in southern Newfoundland (Dubé et al. 1996; Hibbard et al. 2006).
The early Paleozoic margin of Laurentia formed by Neoproterozoic rifting and is known as the Humber Zone (e.g., Waldron et al. 1998). Rifting occurred in two stages, initially opening the Iapetus Ocean and then subsequently a smaller oceanic area
(Taconic Seaway) when a Laurentian fragment (Dashwoods block) broke away,
(Waldron and van Staal 2001). This part of Newfoundland preserves a record of the interaction between oceanic terranes of the Iapetus Ocean and Taconic Seaway with the peri-Laurentian Dashwoods block (Waldron and van Staal 2001; van Staal et al. 1996a,
1998; Whalen et al. 1997). In southern Newfoundland the Notre Dame subzone contains deeper, more intensely metamorphosed and structurally deformed rocks than in north- central Newfoundland (Pehrsson et al. 2003). It is composed of ophiolitic remnants, melange with a variety of mafic through felsic paragneissic rocks, which have been 41
intruded by tonalitic to granodioritic metaplutonic rocks; this area has been referred to as the “sea of tonalite” (Fox and van Berkel 1988; Hall and van Staal 1999).
Peri-Gondwanan rocks in southwestern Newfoundland include gneissic rocks located between the Cape Ray and Isle-aux-Morts faults (Brown 1977), now known as the Grand Bay and Port-aux-Basques complexes (Valverde-Vaquero et al. 2000). These rocks are considered to be part of the peri-Gondwanan margin (Gander Zone) of the
Iapetus Ocean (Williams et al. 1988; Lin et al 1994; Hibbard et al. 2006).
The Hermitage Flexure area to the east is generally assigned to the Exploits
Subzone (Hibbard et al. 2006). It includes a Neoproterozoic to Early Ordovician
“basement complex” overprinted by Ordovician and Silurian-Devonian events, including abundant plutons.
These zones/subzones in southwestern Newfoundland are described here from west to east.
2.6.2 Humber Zone
The eastern boundary of the Humber zone in central Newfoundland is the Baie
Verte-Brompton line, which in the area of Fig. 2.2a is coincident with the Cabot (or Long
Range) Fault. The Humber Zone in southwestern Newfoundland consists of allochthonous ophiolitic and sedimentary rocks, and an underlying autochthonous to parautochthonous assemblage (Williams and Stevens 1974). The lower assemblage unconformably overlies the Grenvillian basement, which includes the Indian Head
Complex and Steel Mountain Inlier. The Indian Head Complex is composed of foliated, dioritic to granodioritic gneiss, anorthosite, and layered gabbroic rocks that have been cut 42
by foliated granitic rocks (Williams 1985). The Indian Head Complex gneisses are deeply weathered at the northeastern contact with the overlying sedimentary succession, indicating that the basement rocks were exposed for a prolonged period of time before the sedimentary units were deposited on top of them (Palmer et al. 2002). The Steel
Mountain Inlier to the east consists mainly of Mesoproterozoic anorthosite and related rocks.
The Early Cambrian to Middle Cambrian Labrador Group is composed of mixed siliciclastic and carbonate rocks and unconformably overlies Grenvillian basement. It marks the base of the Cambrian shelf sequence (James et al. 1989; Knight 1991; Knight and Cawood 1991).
The Middle Cambrian to Upper Cambrian carbonate rocks of the Port au Port
Group (Fig. 2.2) are composed of three formations: March Point, Petit Jardin and Berry
Head (Knight and Boyce 2000). The March Point and lower Petit Jardin formations are composed of shale, laminated calcareous argillite containing siltstone, red and grey silty mudstone, dolomitic, argillaceous and shaly ribbon and parted limestone, bedded and burrowed lime mudstone and wackestone, oolitic grainstone, intraclastic rudstone and floatstone, stromatolitic limestone and dololaminite and other dolostones (Knight and
Boyce 2000). The upper Petit Jardin Formation is composed of buff to yellow- weathering, micro to finely crystalline, light grey and grey dolostone and shale (Knight and Boyce 2000). The Berry Head Formation is composed of a basal marker of cherty, thrombolytic and stromatolitic, dark grey dolostone, which is overlain by a middle succession of thick bedded dolostone followed by an upper unit of intercalated limestone and dolostone (Knight and Boyce 2000). 43
The Lower Ordovician to Middle Ordovician St. George Group conformably overlies the Port au Port Group and is composed of limestone, dolomitic limestone, dolostone, and minor calcareous and dolomitic shale (Knight and James 1987). The St.
George Group limestone and dolomite package is 500 m thick (Knight et al. 1991).
The Middle Ordovician Table Head Group is composed of several carbonate- dominated formations, including Table Point, Table Cove, and Cape Cormorant (Stenzel et al. 1990). It conformably or unconformably in most places overlies the St. George
Group (Knight 1987).
The Middle Ordovician Goose Tickle Group (Fig. 2.2a) is composed of clastic rocks and overlies the Table Head Group. It includes thin basal units of dark shale with turbiditic sandstone and siltstone containing detritus from both the shelf succession and the Humber Arm Allochthon in the upper units (Quinn 1988, 1991; Stenzel at al. 1990;
Corney 1991). Waldron et al. (1993) noted that the Goose Tickle Group is composed of three types of conglomerate interbedded with sandstone and shale.
The Humber Arm Supergroup is composed of deep water equivalents of the shelf succession and occurs in the Humber Arm Allochthon. Local deformation of the units produced mélange-like fabrics during transportation (Waldron 1985; Waldron et al 1988).
Late Cambrian to Early Ordovician ophiolite of the Bay of Islands and Littleport complexes were also transported in the Humber Arm Allochthon, derived from arc- related oceanic crust (Jenner et al. 1991).
Carbonate rocks and shale of the Upper Ordovician Long Point Group and the overlying predominantly red clastic sedimentary rocks of the Silurian Clam Bank
Formation unconformably overlie both the Cambrian-Ordovician shelf sequences and the 44
rocks of the Humber Arm Allochthon (Stockmal and Waldron 1990; Waldron et al.
1993).
2.6.3 Notre Dame Subzone
The Notre Dame subzone includes metasedimentary rocks of the Dashwoods block and varied ophiolitic rocks with a wide range in ages (Waldron and van Staal
2001). The Dashwoods block represents a microcontinent that formed the basement for the Notre Dame arc that was active from the Early Ordovician to Early Silurian (489-435
Ma) (Whalen et al. 1997; Waldron and van Staal 2001; van Staal 2007). During the Late
Ordovician Taconic orogeny, collision of the Dashwoods block with the Laurentian margin caused regional deformation and high grade metamorphism, this was followed by a late syn to post kinematic magmatism with rapid uplift in the Early Silurian (Pehrsson et al. 2003; Whalen et al. 2006).
The Long Range Ultramafic-Mafic Complex in the southern part of the Notre
Dame Subzone is interpreted to be part of the Lush’s Bight ocean tract, and is composed of gabbro, pyroxenite and homogeneous harzburgite, underlain by metasedimentary mélange containing ophiolite-derived blocks (Dunning and Chorlton 1985; Hall and van
Staal 1999). Similarities of the tectonic history of the Long Range Ultramafic-Mafic
Complex to that of the Lush’s Bight ophiolite led Lissenberg et al. (2005) to interpret it as part of the Lush’s Bight oceanic tract. The Lush’s Bight oceanic tract includes the oldest ophiolitic rocks of the Notre Dame Subzone (508-501 Ma), composed mostly of sheeted dykes and pillow basalts in the northern part of the subzone (Elliot et al. 1991;
Swinden et al 1997; Kurth et al. 1998). The emplacement of the Long Range Complex 45
on the Dashwoods microcontinent occurred prior to 488 Ma, as indicated by the ophiolite and underlying mélange being cut by ca. 488 Ma granodiorite (Dubé et al. 1996).
The Baie Verte oceanic tract formed during Taconic Seaway subduction at 489-
484 Ma (Dunning and Krogh 1985; Cawood et al. 1996; Kurth et al 1998). The metamorphosed mélanges in the area contain various mafic and ultramafic inclusions that include amphibolite, serpentinized dunite, pyroxenite and gabbro (Fox and van Berkel
1988).
Most of the Notre Dame subzone consists of magmatic material formed in the
Cambrian-Ordovician Notre Dame arc. It includes voluminous tonalite and granodiorite plutons formed in two phases: 489-477 Ma and 469 to 459 Ma (Whalen et al. 1997; van
Staal 2007). The plutons vary from strongly to non-foliated and contain metamorphic xenoliths of mafic and ultramafic composition, including amphibolite, metagabbro, and metapyroxenite; magma mingling of leucocratic granitoid and mafic compositions has occurred in various places (Brem et al. 2003; Pehrsson et al 2003).
The Cape Ray Igneous Complex consists of variably deformed intermediate to felsic plutonic rocks, interpreted to be remnants from the Notre Dame Arc (Whalen et al.
1997).
The Windsor Point Group (Fig. 2.2a) includes an ignimbrite subunit which unconformably overlies ca. 469 Ma tonalite of the Cape Ray Igneous Complex, and rhyolite feeder dykes intruded the tonalite (Wilton 1983). The felsic volcanic member is overlain conformably by conglomeratic rocks with clasts composed mainly of the felsic volcanic material from the underlying member, along with rare clasts from the Cape Ray
Igneous Complex (Wilton 1983). The conglomerate member is overlain by intercalated 46
chlorite and sericite schist member with interbeds of chert, limestone, conglomerate, graphite schist, and rhyolite with small gabbroic intrusions; these rocks form 65% of the
Windsor Point Group (Wilton 1983). Felsic volcanic rocks of the Windsor Point Group yielded an Ordovician U-Pb (zircon) age of 453 +5/-4 Ma (Dubé et al. 1996).
2.6.4 Port-aux-Basques and Meelpaeg Subzones (Gander Zone)
Rocks interpreted to be related to the Gander Zone of central and eastern
Newfoundland occur in two areas in southwestern Newfoundland, separated by faults and the Devonian Rose Blanche Pluton. The southern area is here termed the Port-aux-
Basques subzone to distinguish it from the larger more northerly area known as the
Meelpaeg subzone. The Port-aux-Basques subzone is located between the Grand Bay fault on the northwest and the Isle-aux-Morts fault on the east, and is dominated by the
Port-aux-Basques and Grand Bay complexes (Dubé et al. 1996; Valverde-Vaquero et al.
2000).
The Grand Bay Complex is an elongate belt of metamorphic rocks located south of the Cape Ray Fault (Fig. 2.2a). During the Late Silurian to Early Devonian, high angle oblique thrusting placed the Grand Bay Complex over the low-grade Windsor Point
Group along the Cape Ray Fault (Valverde-Vaquero et al. 2000). The Grand Bay
Complex is composed of gedrite-bearing schist and metapsammite with abundant intercalations of amphibolite, minor coticule beds, and orthogneiss (van Staal et al.
1996a). The 206Pb/238U age of metamorphic titanite in the complex is 412 +/- 2 Ma
(Dunning et al. 1990b). The 40Ar/39Ar cooling age of hornblende is 406 – 393 Ma and
403 Ma for biotite (Burgess et al. 1995; Dubé et al. 1996). The Grand Bay Complex is 47
intruded by the Isle-aux-Morts granite with a U-Pb (zircon) age of 386 ± 3 Ma which stitches the Cape Ray Fault (Dubé et al. 1996). The Grand Bay Complex is in contact on the southeast with the Port-aux-Basques Complex at a thrust-sense shear zone known as the Grand Bay Fault (Burgess et al. 1992, 1995).
The Port-aux-Basques Complex (Fig. 2.2a, b) is composed of quartzofeldspathic paragneiss, amphibolite, minor metapelite, rare coticules, and abundant orthogneiss. The complex includes Port-aux-Basques granite and the Kelby’s Cove and Margaree orthogneiss bodies (van Staal et al. 1996a, 1996b). The complex underwent partial metamorphism in the kyanite zone, sillimanite zone, and in the transition between sillimanite and the sillimanite with K-feldspar zones (Valverde-Vaquero et al. 2000).
The U-Pb (zircon) age for syntectonic granite in the complex is ca. 450 Ma. A U-Pb
(monazite) age from the migmatitic paragneiss is 420-415 Ma (van Staal et al. 1994). The
40Ar/39Ar cooling ages obtained for hornblende and muscovite are 407-399 Ma and 394-
391 Ma, respectively (Burgess et al. 1995).
The Margaree Orthogneiss is composed mostly of hornblende-bearing tonalitic orthogneiss, and less abundant granitic orthogneiss, amphibolite, and ultramafic rocks
(Valverde-Vaquero et al. 2000). Tonalitic orthogneiss with subordinate dioritic and granodioritic rocks forms 60% of the unit (Valverde-Vaquero et al. 2000). Based on U-
Pb (zircon) dating the igneous crystallization age of the tonalitic orthogneiss is 474 +14/-
4 Ma. The granitic orthogneiss intruded the tonalitic gneiss and contains enclaves and/or dykes of amphibolite, both in the coastal Fox Roost and the inland Grandy’s Brook sections (Valverde-Vaquero et al. 2000). The U-Pb (zircon) age of the granitic orthogneiss in the Fox Roost section is 472 ± 2.5 Ma, in the Grandy’s Brook section it 48
was dated at 465 ± 3 Ma. The U-Pb (titanite) ages are similar in both locations dated at
410 ± 2 Ma and 411 ± 2 Ma, respectively (Valverde-Vaquero et al. 2000).
The Kelby's Cove orthogneiss is composed principally of mafic to felsic orthogneiss with rare layered ultramafic bodies, all possibly coeval (van Staal et al.
1996c). Both the Margaree and Kelby's Cove orthogneiss are cut by intrusions dated at ca. 470 Ma (van Staal et al. 1996b). The Kelby’s Cove orthogneiss occurs in both the
Grand Bay and Port-aux-Basques complexes, whereas the Margaree orthogneiss occurs only in the Port-aux-Basques Complex (Schofield et al. 1998). The overall lithological assemblages of both the Margaree and Kelby’s Cove orthogneiss units are similar, but the
Kelby’s Cove orthogneiss contains garnet and gedrite indicating slight chemical differences between the two orthogneisses (Schofield et al. 1998).
The Meelpaeg subzone contains lower grade metasedimentary rocks assigned to the Gander Group, intruded by the Devonian North Bay Batholith.
2.6.5 Exploits Subzone
The Isle-aux-Morts fault zone separates the Port-aux-Basques Complex from the
Harbour le Cou Group, considered part of the Exploits subzone (Fig. 2.2a, b). The Rose
Blanche Pluton cuts the fault and adjacent units, separating this part of the Exploits subzone from its continuation to the east (Fig. 2a).
The Harbour le Cou Group is divided into two formations, Grandy’s and Otter
Bay. The Grandy’s Formation is composed of semipelitic and pyritiferous pelitic schist interlayered locally with coticule beds (Schofield et al. 1998). The Otter Bay Formation is composed of intensely deformed, rhythmically interlayered psammitic and pyritiferous 49
pelitic metasedimentary rocks that have been metamorphosed to garnet-sillimanite schist.
It also includes hornblende-clinopyroxene metagabbro and pillowed metabasalt (O’Brien et al. 1991; Schofield et al. 1993; Lin et al. 1993), and yielded a U-Pb (zircon) age of 419
± 2 Ma. It is intruded by the ca. 419 Ma two-mica Rose Blanche granite (Benn et al.
1993; van staal et al. 1994, 1996c). The western part of the Harbour le Cou Group provided a U-Pb (titanite) age of 418 ± 9 Ma (Burgess et al. 1995).
The Bay Le Moine Shear Zone and Rose Blanche Pluton separate the Harbour le
Cou Group from the Bay du Nord Group which dominates the rest of the Exploits subzone in southwestern Newfoundland (Fig. 2.2a). Near the Bay le Moine shear zone, the rocks are thin-bedded phyllitic siltstone and mudstone, some which are tuffaceous and include a rhyolite sill or flow (Lin et al. 1993). Farther east, the rocks are graded, thin- to thick-bedded immature sandstone to siltstone and conglomerate (Lin et al. 1993).
Feldspar and blue quartz fragments are abundant in the sandstone, with well-developed graded bedding and near complete Bouma sequences in places (Lin et al. 1993). Farther east, the Bay du Nord Group contains thick beds of immature sandstone, with abundant lithic and feldspar fragments (Lin et al. 1993). U-Pb (zircon) dating of foliated felsic tuff samples yielded a crystallization age of 466 ± 3 Ma (Dunning et al. 1990b). The rocks of the Bay du Nord Group have been metamorphosed regionally only to greenschist facies but are locally contact metamorphosed to cordierite and/or andalusite grade by the ca.
416 Ma La Poile Batholith and 390 ± 2 Ma Petites Granite (Lin et al. 1993).
50
2.6.6 Burgeo Subzone
The name Burgeo subzone is used informally here for the part of the Exploits subzone south of the Bay d’Est Fault (Fig. 2.2a, b). This area is dominated by Silurian-
Devonian plutons (described separately below) but also includes Precambrian to Silurian units absent in the Exploits subzone to the north. The Precambrian units occur in two small areas, one in the west south of the Cinq Cerf Fault Zone and the other in the east at
Grey River (Fig. 2.2a).
In the western area, Precambrian units include the Cinq Cerf Gneiss, Whittle Hill
Sandstone, Third Pond Tuff, Roti Intrusive Suite, and other gabbroic to granitic rocks
(O’Brien et al. 1991; Valverde-Vaquero et al. 2006). The Cinq Cerf Gneiss is a composite unit composed of supra-crustal and intrusive rocks with composite gneissic fabric cut by the Silurian Western Head granite (Valverde-Vaquero et al. 2006). The gneiss is composed of amphibole-rich and quartzofeldspathic rocks with gabbroic pods, deformed mafic dykes and granitic orthogneiss (Valverde-Vaquero et al. 2006). The granitic orthogneiss has a U-Pb (zircon) protolith age of 675 +12/-11 Ma, and the cross- cutting Sandbank Point Gabbro has yielded an upper intercept age of 557 +14/-5 Ma
(Valverde-Vaquero et al. 2006). The Whittle Hill Sandstone and Third Pond Tuff form a conformable succession of greenschist-facies sedimentary and tuffaceous volcanic rocks
(O’Brien et al. 1991). They were intruded by tonalite of the Roti Intrusive Suite, and tuff has been dated at 585-582 Ma. The Roti Intrusive Suite includes granite, granodiorite, and tonalite with ages of 568-563 Ma (Valverde-Vaquero et al. 2006). Younger units in this complex area include the Wild Cove granite, dated at 499 +3/-2 Ma, which was in turn intruded by the Ernie Pond Gabbro dated at 495 ± 2 Ma (O’Brien et al. 1991). The 51
Western Head granite, a composite intrusion composed of granite and granodiorite, contains deformed enclaves of the Cinq Cerf gneiss and the Sandbank Point metagabbro.
It yielded a U-Pb (zircon) age of 431.5 ± 1.1 Ma (Valverde-Vaquero et al. 2006).
These Precambrian and Cambrian rocks are interpreted to form the basement under the La Poile Group, composed of subaerial felsic volcanic and quartz-rich fluvial sedimentary rocks (O’Brien et al. 1991). The La Poile Group generally has a relatively simple deformation history compared to older units described above, and has been regionally metamorphosed under lower greenschist facies conditions. Two tuff samples yielded U-Pb (zircon) ages of 429 ± 2 Ma and 422 ± 2 Ma (O’Brien et al. 1991).
In the Grey River area, metavolcanic and metasedimentary rocks occur in association with a belt of amphibolite, hornblende diorite, migmatite, orthogneiss, and migmatized schists (Blackwood 1985; Dunning and O’Brien 1989). Dunning and
O’Brien (1989) inferred a magmatic protolith age of 686 +33/-15 Ma and a metamorphic age of 579 ± 10 Ma for the gneiss, and an age of 544 ± 5 Ma for lower grade felsic tuffs north of the gneissic rocks.
2.6.7 Silurian-Devonian Plutons
Silurian to Devonian plutons are present locally in the Notre Dame subzone, but are a major component of the Meelpaeg, Exploits, and Burgeo subzones (Fig. 2.2a).
The Burgeo intrusive suite is a large polyphase body composed of gabbroic and granitic rocks (O’Brien and Dickson 1986; Dickson et al. 1989). The oldest rocks in the suite include hornblende-bearing biotite granodiorite, granite, and tonalite emplaced into
Ordovician host rocks synkinematically as sheets. K-feldspar porphyritic granite cross- 52
cuts these older intrusions and forms most of the suite; medium-grained biotite ± muscovite granite is the youngest part of the suite (Dickson et al. 1989). U-Pb dating has indicated an age of ca. 429 Ma for hornblende-bearing biotite granodiorite and ca. 415
Ma for muscovite-bearing granite (Dunning et al. 1990b).
The North Bay Batholith is similar to the Burgeo intrusive suite in being a variably deformed, composite body, made up of several syn-tectonic granodiorite, granite, and muscovite-bearing tonalite and granite plutons (Dickson 1990).The suite also includes post-tectonic, coarse-grained porphyritic biotite ± muscovite granite
(Dickson 1990). Ordovician deformation affected the oldest plutons whereas the youngest plutons are massive with xenoliths of polydeformed Ordovician strata (Dickson
1990). Samples from the youngest massive porphyritic biotite granite (Dolland Brook) yielded a 207Pb/206Pb (zircon) upper intercept age of 396 +6/-3 Ma, interpreted to be the age of crystallization of the granite (Dunning et al. 1990b). The ca. 419 Ma two-mica
Rose Blanche granite (Benn et al. 1993; van Staal et al. 1994, 1996c) is likely related to the North Bay Batholith.
The Chetwynd Granite is divisible into an area of K-feldspar +/- quartz porphyritic granite containing adamellite variants, and fine- to coarse-grained equigranular granite (Dickson et al. 1989). The western part of the Burgeo intrusive suite is intruded by the Chetwynd granite, the granite also crosscuts foliations in all of the adjacent units (Chorlton and Dallmeyer 1986; O’Brien and Tomlin 1985; O’Brien 1987).
A crystallization age of 390 ± 3 Ma has been established for this intrusion (O’Brien et al.
1991).
53
2.7. Carboniferous Rocks in Southwestern Newfoundland
Relatively undeformed Upper Devonian and Carboniferous sedimentary rocks make up the sediment fill of the onshore part of the Bay St. George sub-basin on the southern part of the Humber Zone (Fig. 2.2a). They are subdivided into three groups
(Knight 1983; Miller et al. 1990; Hall et al. 1992). The Late Devonian to Early
Mississippian Anguille Group is the oldest and thickest unit, and is equivalent of the
Horton Group in Cape Breton Island. It occurs mainly in a narrow basin which is an eastward extension of the Maritimes Basin (Bradley 1982; Williams and Grant 1998).
The Anguille Group is composed of nonmarine siliciclastic, red to grey fluviodeltaic shale to coarse sandstone, with local conglomerate (Knight 1983). It is interpreted to have been deposited in a deep lake in a narrow, elongate fault-bounded sub-basin (Knight
1983). The sediments were derived from uplands to the southeast (Miller et al. 1990).
The rocks of the Anguille Group are well cemented and highly competent.
The overlying Codroy Group is the equivalent of the Windsor Group of Nova
Scotia, and similarly reflects both marine and nonmarine depositional environments
(Miller et al. 1990). The Codroy Group is of Late Mississippian age and consists of marine and nonmarine sequences of siliciclastic rocks, evaporites, and calcareous rocks
(Knight 1983). The Codroy Group was deposited over a greater area than the Anguille
Group (Miller et al. 1990).
The Barachois Group consists of red and grey siltstone-sandstone sequences of fluvial origin with minor mudstone and coal (Knight 1983). It was deposited in a fluvial environment with meandering river systems and flood plains (Miller et al. 1990). The 54
upper part of the Barachois Group contains coals and finer sediments that correlate with the lowermost coal units in Nova Scotia and New Brunswick (Solomon 1986).
2.8 Offshore Geology
The offshore area around southwestern Newfoundland and Cape Breton Island is part of two Carboniferous basins, the Magdalen Basin to the northwest and the Sydney
Basin to the south (Fig. 1.4). Both are part of the larger Maritimes Basin, initiated in the
Late Devonian on older rocks of the Appalachian orogen as a composite basin consisting of several depocentres (Gibling et al. 1987; McCutcheon and Robinson 1987; Williams and Grant 1998), although the mechanism of basin formation is not fully understood
(e.g., Bradley 1982; McCutcheon and Robinson 1987; Lynch and Tremblay 1994;
Murphy et al. 1999). These basins contain late Devonian to Carboniferous (in places
Permian) rocks equivalent to the thinner successions exposed onshore in Cape Breton
Island and southwestern Newfoundland.
The oldest basin-fill rocks in the Magdalen Basin are mafic and felsic volcanic rocks and interbedded terrestrial sedimentary rocks, the offshore equivalents of the Fisset
Brook and Lowland Cove formations in western Cape Breton Island. They are overlain conformably to unconformably by the latest Devonian to Early Carboniferous Horton
Group, also largely deposited in restricted graben. Later sedimentary units of the basin are regionally more widespread and comprise the shallow marine and nonmarine
Windsor Group (mid-Viséan) and the nonmarine coal-bearing Mabou, Cumberland, and
Morien/Pictou groups (late Viséan to early Permian). The evaporite sequences in the 55
Magdalen Basin are thickest near its southeastern margin, an area dominated by salt tectonics (e.g., Langdon and Hall 1994).
The Bay St. George sub-basin is part of the larger Magdalen Basin, and includes
Carboniferous rocks onshore in southwestern Newfoundland (as described above) and
Carboniferous rocks in the offshore under St. Georges Bay. The onshore and offshore parts of the sub-basin are separated by the St. Georges Bay Fault which follows the southern coastline of St. Georges Bay (Fig. 2.3). The offshore part of the basin includes northern and southern half-graben separated by the Central Bay Fault. The pre-
Carboniferous basement of Bay St. George sub-basin is likely composed of Humber Zone
Precambrian rocks similar to those found in the Indian Head Complex, as well as overlying Late Precambrian to Silurian rocks of the Humber Zone (Miller et al. 1990;
Enachescu 2006). Sediment fill in the northern half-graben reaches a thickness of 3500 m above pre-Carboniferous basement, whereas the larger southern graben contains a thicker sequence, up to 6 km based on potential field modeling by Kilfoil (1988). A well in the northern half-graben penetrated 400 m of Carboniferous rocks (Barachois and
Codroy formations) before crossing into the underlying Ordovician Long Point Group
(Enachescu 2006). The same units appear to be present in the southern half-graben, and the Anguille Formation appears to be absent in the offshore (Miller et al. 1990). The St.
Georges Bay sub-basin, especially the southern half-graben, is structurally complex as a result of salt tectonics and transtensional faulting (Enachescu 2006).
In the Sydney basin, three distinctive units were identified in the Carboniferous basin fill by Pascucci et al. (2000) based on seismic line interpretations. Unit 1 occurs on pre-Carboniferous basement and was correlated with the Horton Group. The lower part of 56
Unit 1 was interpreted to consist of well stratified volcanic and sedimentary rocks equivalent to the Fisset Brook Formation, although that unit does not occur in the adjacent onshore part of Cape Breton Island. The quality of the seismic data is such that the presence or absence of the mid-Devonian McAdams Lake Formation, which underlies the Horton Group onshore, cannot be determined in the offshore; it might be included in the “basement” in the interpretations of Pascucci et al. (2000). The middle part of unit 1 could be shale-rich, but could also be volcanic or other rock types with similar seismic impedance (Pascucci et al. 2000). Overlying unit 2 is correlated with the Windsor and
Mabou groups, and unit 3 as the Pictou and Morien groups (Pascucci et al. 2000).
The boundary between the Magdalen and Sydney basins approximately coincides with the inferred extension of the Cabot fault from southwestern Newfoundland to Cape
Breton Island, where it is typically connected to the Aspy fault. However, the fault is not a continuous feature but has numerous offsets (Fig. 2.3). The inferred trace of the fault in the area is flanked by two linear graben that preserve up to 6 km of Devonian-
Carboniferous sedimentary rocks (Langdon and Hall 1994). The northwestern graben is named Searston, bounded on the north by a fault system inferred by Langdon and Hall
(1994) to be a continuation of the Hollow fault and the St. Georges Bay Fault. In this interpretation, the Carboniferous rocks onshore in southwestern Newfoundland would be the continuation of rocks in the Searston graben. The southern graben, Cape Ray, is bounded on the southeast by the inferred extension of the Cape Ray fault (Fig. 2.3). In the interpretation of Langdon and Hall (1994), that fault does not appear to extend to Cape
Breton Island and instead terminates south of St. Paul Island by bending into east-west faults and joining the Cabot fault (Fig. 2.3). 57
The Searston and Cape Ray graben contain typical Maritimes Basin stratigraphic units. The many salt structures in the Searston Graben are indicative of a thick Windsor-
Codroy sequence (Langdon and Hall (1994 (Langdon and Hall (1994). The lack of salt structures east of the Cabot fault and stratigraphic association to the Sydney Basin could indicate that the lower Windsor-Codroy Group is missing from the deeper basin fill. The low-angle thrust faults under the Cabot Strait appear to be décollement faults that occur at the base of the Windsor (=Codroy) Group and are associated with salt structures rising upwards. The more competent Horton Group commonly behaved as a ramp to allow the salt-lubricated Windsor Group sedimentary rocks to thrust out of the basin (Langdon and
Hall 1994). 58
Fig. 2.1 Geologic map of eastern Cape Breton Island showing the major rock units after Raeside and Barr (1992) and Lin et al. (2007). Abbreviations: AF, Aspy Fault; BB, Black Brook Granitic Suite; BL, Bell Lakes Plutonic Suite; BH, Boisdale Hills pluton; BP, Birch Plain Granite; Be, Benacadie Brook Formation; BR, Barachois River Formation; C, Cape North Group; Ca, Cameron Brook Granodiorite; Ch, Cheticamp Lake Gneiss; Cl, Clyburn Brook formation; CM, Cross Mountain Pluton; CS, Cape Smokey Pluton; FV, Frenchvale Road Metamorphic Suite; GB, Glasgow Brook Orthogneiss; GF, Gisborne Flowage Quartz Diorite; IB, Indian Brook Granodiorite; In, Ingonish Beach Gneiss; IR, Ingonish River Tonalite; KG, Kellys Mountain Gneiss; KM, Kellys Mountain Granite; KR, Kathy Road Diorite; M, Money Point Group; Ma, Margaree Pluton; MB/GRF, McIntosh Brook-George River Fault; MC, Mount Cameron Syenogranite; MF, McMillan Flowage Formation; NH, Neils Harbour Gneiss; PP, Price Point Formation; PS, Park Spur Granite; RF, Red River Fault; SB, Sarach Brook Metamorphic Suite; SH, Ski Hill Granodiorite; Sh, Shunacadie pluton’ TL, Timber Lake Diorite; WBF, Wilkie Brook Fault; WC, Wreck Cove Dioritic Suite; WS, Wilkie Surgarloaf Granite.
59
Fig. 2.2 (a) Geologic map of southwestern Newfoundland compiled after Dubé et al. (1996), Schofield et al. (1998), Valverde-Vaquero et al. (2000, 2006), and Hibbard et al. (2006). Map legend is in Fig. 2.2b. Fault abbreviations: BMSZ, Bay le Moine Fault Zone; BDFZ, Bay d’Est Fault Zone; CF-LRF, Cabot Fault – Long Range Fault; CRF, Cape Ray Fault; IMFZ, Ile-aux-Morts Fault Zone; RIL, Red Indian Line. Unit abbreviations: BB, Burgeo Batholith; BdN, Bay du Nord Group; CC, Cinq Cerf Gneiss; Cw, Chetwynn Granite and similar plutons; DW, Dashwoods Block; GB, Grand Bay Complex; GG, Gander Group; GR, Grey River Enclave; HlC, Harbour le Cou Group; IH, Indian Head Complex; KC, Kelby Cove Orthogneiss; LP, La Poile Group; MO, Margaree Orthogneiss; NB, North Bay Batholith; R, Roti Granite; RB, Rose Blanche Batholith; SM, Steel Mountain Inlier;
60
Fig. 2.2 (b) Legend for geologic map in Figure 2.2a.
61
Fig. 2.3. Geological map of the Cabot Strait area from Langdon and Hall (1994).
62
3.0 METHODS
3.1 Sources of Digital Magnetic and Gravity Data
Most of the digital magnetic and all of the gravity data used in this project were obtained from the Geological Survey of Canada, downloaded from the Geoscience Data
Repository website (www.gdr.nrcan.gc.ca). Additional digital aeromagnetic data for the
St. George’s Bay area were obtained from the Newfoundland and Labrador Department of Natural Resources website
(http://www.geosurv.gov.nl.ca/airborne/disp_airborne.asp?SURVEY_ID=DN08002).
The magnetic and gravity data were acquired in point form in ASCII (American
Standard Code for Information Interchange) text format composed of three values
(longitude/latitude/magnitude). The data were obtained in this format to allow them to be gridded in a desired datum and projection. The datum used for all of the acquired digital data is World Geodetic System 1984 (WGS84), using a geographic coordinate system.
Grids were generated from the gravity and magnetic digital data using Generic Mapping
Tools (GMT 4.5.7), open-source software that includes about 65 tools for the manipulation of geographic and Cartesian data sets. The GMT software was developed and is maintained by Paul Wessel and Walter H.F. Smith at (http://gmtsoest.hawii.edu/).
3.2 Magnetic Data
The digital magnetic data obtained from the Geological Survey of Canada (GSC) are composed of a compilation of IGRF (International Geomagnetic Reference Field) reduced marine survey data and aeromagnetic (1 km) gridded data. The adjustments to the marine survey data were made by Verhoef et al. (1996) to account for the variations in the magnetic field, correction of cross-over errors, and the filtering and removal of 63 acquisition and gridding artefacts. Wavelengths exceeding 400 km were removed from the marine data grid, and then the marine and aeromagnetic survey blocks were assembled into a new 500 m grid, which are the data used for this study.
The aeromagnetic data set for the St. George’s Bay area obtained from the
Newfoundland and Labrador Department of Natural Resources website was collected by
Sander Geophysics Ltd. for the Hunt Oil Company in 1993. The airborne survey was flown with a line spacing of 7500 m in the NE direction, and 3000 m in the SE direction.
The data were converted from NAD 27, UTM Zone 21, to WGS84 at the Newfoundland and Labrador Department of Natural Resources. This data set was adjusted and leveled so that it could be merged smoothly with the magnetic data obtained from the GSC.
The two data sets were merged into one file before gridding. Gridding of the magnetic data used a grid spacing of 0.00625 degrees (~1 km) with an adjustable tension continuous curvature surface algorithm using a cylindrical Mercator projection; the datum remained WGS84 (Wessel and Smith 2012).
For the total magnetic field (TMF) anomaly map the data were displayed using
GMT in UTM projection. Additional data filtering was applied to enhance anomalies in the study region. The first vertical derivative of the total magnetic field provides sharper resolution of near-surface features, and is mathematically derived from the total-field anomaly map (Sharma 1997). Preparation of the first vertical derivative of the TMF anomaly required the use of a Fast Fourier Transform (FFT) to filter and differentiate data (Wessel and Smith 2012). The filter is a cosine–taper with a low pass filter (-F -/-
/15000/1000) designed to cut wavelengths less than 1000 m, while allowing wavelengths greater than 15 000 m to pass; the values in between the two limits were cosine-tapered
(Wessel and Smith 2012). The same FFT filter parameters were applied to the second 64 derivative and downward continuation maps. The FFT function allows mathematical operations to be performed in the frequency domain before the data are converted back into space domain (Wessel and Smith 2012).
In GMT the first vertical derivative was calculated using a directional derivative function. The derivative parameters included a normalized gradient value of 0.5 using a
Laplace distribution (Wessel and Smith 2012). The first vertical derivative also requires a secondary FFT function, which is differentiating the field (d(field)/dz).
The second vertical derivative enhances and delineates the intra-basement anomaly sources and plan-view boundaries. The zero values of the inflection points of the magnetic anomalies on the second vertical derivative map can predict the shape and edges of the source causing the anomaly (Sharma 1997). Calculating the second derivative requires the same steps as for the first derivative but the field is differentiated twice (Wessel and Smith 2012).
The downward continuation image was generated in GMT by applying a second
FFT function specifically for continuation. It was achieved by assigning a negative value
(-400 m) which the software assumes is downward continuation (Wessel and Smith
2012).The process of downward continuation takes the observed data and converts them to what they would have been if the data were collected at depth closer to the anomaly
(Sharma 1997). The depth of 400 m was selected because it pushes the data below the average water depth in the Laurentian Channel while preventing the issues of increasing noise and artefacts in the data.
65
3.3 Gravity Data
The digital gravity data (ASCII) file obtained for this study is a compilation of gravity measurements collected from marine and ground surveys. The spacing for measurements was 5-10 km on land, and 2-5 km for ship tracks in the offshore, with an increase in the number of survey lines in targeted areas (Fig. 3.1). The drift correction had been applied to both the land and marine survey data to correct for changes in the environment such as air temperature and pressure during the survey and creep of the gravimeter spring (Sharma 1997). Latitude correction had also been applied to both data sets, which removes the effects of increased gravity from the equator to the poles as a result of decreasing the Earth’s radius and centrifugal force (Sharma 1997). They had also had the free-air correction applied, to account for the vertical decrease in gravity as elevation increases (Sharma 1997). Bouguer corrections, which take into account the attraction of the material between the reference elevation (sea level) and the location of the station (various elevations about sea level) had also been applied to the on-land data.
The marine data had the tidal correction applied as well as the Eotvos correction to account for the gravity changes caused by the centripetal acceleration of a moving observation platform such as a vessel (Jones 1999). The final corrected land and marine gravity data had been merged and gridded at 2 km intervals.
The gravity anomaly data were re-gridded at 1.5 km (~0.8 minutes) because the data set was collected using wider line spacing than the magnetic data and required a coarser grid to prevent distortion and artefacts in the resulting maps. Like the magnetic anomaly data, the gravity anomaly data were gridded using an azimuthal direction of
315o (illumination) used to display shadow in the data (i.e. horizontal gradient), and a normalized gradient value of 0.5 using a cumulative Laplace distribution. 66
The horizontal gradient of the gravity anomaly data represents the square root of the sum of the squares representing the change in values between adjacent points in the x and y directions. The horizontal gradient of gravity formula takes the derivative in the x- direction Ax = (d(A)/dx), and then the first derivative in the y-direction Ay = (d(A)/dy).
The final step takes the hypotenuse, calculated as the root of the sum of the squares,
((Ax2 )+ (By2)1/2. The horizontal gradient of the gravity anomaly data was derived to locate the edges of units with contrasting densities by delineating contrasting local maxima. The edge of a source body is indicated by the steepest horizontal gradient of the gravity anomaly (Sharma 1997).
3.4 Magnetic Susceptibility Data
The magnetic response produced by a rock consists of an induced component caused by the Earth’s present magnetic field, and a remanent component, which represents relict magnetization from past induced fields that had been imprinted in the rock (Sharma 1997). The ideal interpretation of magnetic data requires knowledge of both components; however, the measurement of remanent magnetization requires specialized laboratory equipment and hence is most often ignored due to the complexity and difficulty of obtaining measurements (Dannemiller and Li 2006; Okiwelu et al.
2011).
The intensity of induced magnetization is dependent on the magnetic susceptibility (k) of the rock. The intensity of magnetization (M) is based on the strength of the induced magnetic field (H) and the magnetic susceptibility (M = kH).
Susceptibility is dimensionless in the c.g.s. system and reflects the concentration of magnetisable material in the material, mainly magnetite. 67
For this study, magnetic susceptibility was measured using rock slabs representing rock units in the Bras d’Or and Aspy terranes and Blair River Inlier in Cape
Breton Island (Fig. 3.2). Measurements were made using a hand-held Exploranium KT-9
Kappameter. Three measurements were taken for each hand sample and then averaged.
The KT-9 Kappameter uses a 10 kHz LC oscillator and an inductive coil used to measure magnetic susceptibility. The measurement is made by comparing the oscillator frequency when away from the sample and when adjacent to it and the difference in frequency between the two measurements is directly proportional to the magnetic susceptibility of the material. The KT-9 Kappameter records susceptibilities between 1 x 10-5 SI units and
999 x 10-3 SI units.
Few susceptibility data are available for rock units in southwestern
Newfoundland. In the models k values for that area are based on data from similar units in Cape Breton Island and elsewhere.
Susceptibility data used in this study are listed in Appendices A and B.
3.5 Specific Gravity Data
Gravity anomalies are caused by lateral changes in density between rock formations. Specific gravity is a unitless measurement obtained when the density of a material is divided by the density of water (1 g/cm3). The average density for most rocks ranges between 1.9 and 2.8 g/cm3 (Sharma 1997). Variation in the density in rocks is related mainly to the minerals present and the porosity of the rock.
No density measurements were made in the present study. For Carboniferous rock units in and near Cape Breton Island, density data from Cook (2005) and King
(2002) were used. Density data for the three Carboniferous units in the St. George’s Bay 68 area were taken from Miller et al. (1990). For pre-Carboniferous units, density data from similar rock types were taken from Tenzer et al. (2011). Tenzer et al. (2011) reported rock densities for rocks in New Zealand, thus providing general values for most common igneous and metamorphic rock types.
3.6 Seismic Data
Seismic data used in this study are public-domain data and include paper copies of seismic lines 86-5A, 86-5, and 86-4 (Fig. 3.3), recorded in 1986 by Geophysical
Service Incorporated (GSI) for the Geological Survey of Canada as part of the Lithoprobe and Frontier Geoscience projects (Marillier et al. 1989). Industry seismic line interpretations for the St. George’s Bay area were obtained from Langdon and Hall
(1994) and Miller et al. (1990). Interpretations for industry seismic lines in the Cabot
Strait were taken from published papers by Marillier et al. (1989), Pascucci et al. (2000), and Langdon and Hall (1994). Supplementary information on Langdon and Hall (1994) seismic lines was accessed in Langdon (1996).
3.7 Potential Field Modeling
The forward modeling process for potential field data involves creating hypothetical units to represent the pre-Carboniferous and overlying Carboniferous units and assigning susceptibility and density values based on measured and inferred data. The units in the model are adjusted to produce calculated anomalies that match along the profile lines existing gravity and magnetic profiles. Seismic interpretations are used to constrain the thickness and depth of units below the surface. 69
Two-dimensional modeling was done using GM-SYS® (PRO) 4.8 software. A two-dimensional model produces a profile perpendicular to strike with changes occurring with depth along the direction of the profile. Gravity and magnetic models are “non- unique”, which means that a set of specific magnetic and gravity data can be matched by an infinite number of models. The geological background of the area and use of seismic interpretations constrain the most realistic and reasonable 2D model to the geophysical characteristics of each profile.
The building of the models consists of first importing the magnetic and gravity data for each profile extracted from the magnetic and gravity grids. The subsurface geology is modeled by creating blocks and assigning susceptibility and density values for each rock unit so that on the magnetic and gravity profiles the calculated curve matches the observed curve as closely as possible. In the study area, the models used a present day magnetic field strength of 43.136552 A/m, inclination of 75.686o, and declination of -24.836o. Six models were produced (Fig. 3.4): two models across the Ingonish
Magnetic Anomaly to interpret the cause of this anomaly, three models across the Cabot
Strait to help understand how the geology of Cape Breton Island correlates to that of southwestern Newfoundland, and one model to interpret the sub-surface geology of St.
George’s Bay. 70
Fig.3.1 Location of on-land gravity survey measurements (dots) and off-shore tracklines of marine gravity surveys. Data were compiled and processed by the Geological Survey of Canada (GSC) into a 2 km grid which was obtained from the GSC Geoscience Data Repository for use in this study.
71
Fig.3.2 Geological map of northeastern Cape Breton Island modified from Figure 2.1 showing locations (dots) of samples measured for magnetic susceptibility.
72
Fig.3.3 Locations of seismic reflection line interpretations used in this study. Yellow lines are from Marillier et al. (1989), black lines are from Langdon and Hall (1994), red lines are from Pascucci et al. (2000), and the purple line E20 in the St. George’s Bay area is from Miller et al. (1990).
73
Fig.3.4 Map showing the locations of the six cross-sections selected for forward modeling using magnetic and gravity data. 74
4.0 RESULTS
4.1 Introduction
This chapter begins with the presentation and description of the regional magnetic and gravity maps generated from the database for the study area as described in Chapter
3. Overall characteristics of the potential field signals are described for each of the major fault-bounded blocks or terranes in northeastern Cape Breton Island and southwestern Newfoundland and the intervening offshore area as described in Chapter 2.
Also summarized here are the seismic line interpretations in the offshore part of the study area, and the magnetic susceptibility data base for units in onshore areas where such data are available. In the last section of the chapter, the potential field models are presented for the 6 lines shown on Figure 3.4.
4.2 Magnetic Maps
4.2.1 Total Magnetic Field
The total magnetic field anomaly map (Fig. 4.1) shows subdued anomalies in the southern part of the Bras d’Or terrane, with little change at the inferred boundary with the
Mira terrane. In contrast, the northern part of the terrane displays prominent, mainly linear, anomalies in which range in magnitude between 200 to 500 nT.
The western and central Aspy terrane is characterized by less linear anomalies, ranging in magnitude from 100 to 500 nT. Smaller anomalies also extend along both sides of the inferred boundary between the Bras d’Or and Aspy terranes in the central
Cape Breton Highlands (Fig. 4.1). In comparison, the northeastern part of the Aspy terrane lacks strong anomalies, although some weak anomalies (100-200 nT) in the area trend east-west into the offshore. To the north, strong linear anomalies (100-500 nT) 75 occur along the boundary between the Aspy terrane and Blair River Inlier. The Blair
River Inlier is characterized by numerous strong anomalies (200-500 nT).
In the offshore, the Ingonish Magnetic Anomaly (IMA) is the most prominent feature, ~ 40 km wide (NW-SE) and ~ 50 km wide (SW-NE). The central part of the anomaly shows the highest magnitude (400 – 500 nT). A narrow anomaly on the western side of the main anomaly appears to connect it to Cape Breton Island in the Middle Head area (Fig. 4.1).
In the Cabot Strait, a long narrow anomaly extends offshore from Aspy Bay and appears to widen and increase in intensity (100 to 500 nT) as it nears Newfoundland where it appears to merge with anomalies that characterize the area between the Cabot and Cape Ray faults. To the northwest, a weaker linear anomaly extends from Money
Point through to St. Paul Island, where it fades away. To the southeast (47oN, 59.7oW), a large elliptical but composite-looking anomaly has a more northeasterly trend, and a subtle circular anomaly occurs farther east (47.3oN, 59.2oW). The Sydney Basin displays several weak linear anomalies trending toward Newfoundland, but closer to the coast of Newfoundland, a number of irregular circular to elliptical anomalies are present, many with higher magnitude rims and lower magnitude cores. This pattern appears to continue onshore in the Burgeo subzone, although in general the Burgeo subzone and the rest of the Exploits subzone to the north and west are characterized by muted negative anomalies.
In contrast, the Port-aux-Basques subzone displays more prominent anomalies, including a narrow curvilinear anomaly (magnitude 200-400 nT) extending southwest from the Notre Dame subzone boundary and weakening in intensity in the offshore to the southwest where it intersects the large elliptical anomaly in the Cabot Strait. 76
In comparison, the Notre Dame subzone is much more magnetic. It displays strong positive anomalies in the southwest, and farther north, both positive and negative anomalies, the latter as much as -200 to -400 nT. The Cabot fault coincides with a linear negative magnetic anomaly and marks an abrupt change in magnetic character between the Notre Dame subzone and adjacent Carboniferous rocks of the onshore part of the Bay
St. George sub-basin which overlies the Humber zone. Farther north, a large positive magnetic anomaly (100-500 nT) is present onshore in the Bay St. George sub-basin and continues offshore into St. George’s Bay with a weakened signal (100-300 nT). Another large positive anomaly (100- 500 nT) extends from the Port au Port Peninsula southwest into St. George’s Bay.
4.2.2 First Vertical Derivative
The map of first vertical derivative of the total magnetic field anomalies (Fig. 4.2) provides sharper resolution of many of the anomalies seen in the total field map, indicating that they are caused by relatively near-surface sources.
On Cape Breton Island, the boundary between Mira and Bras d’Or terranes is more obvious, and the southern part of the Bras d’Or terrane looks more like the northern part, with a strongly linear northeast-trending anomaly pattern. The pattern in the Aspy terrane is less linear and more patchy, and the east-southeast trending linear anomalies of the eastern part of the terrane are enhanced. The Blair River Inlier retains its strong positive and negative signals, and contrasts with the linear northeast trend in the Cape
North Peninsula part of the adjacent Aspy terrane.
In the offshore, the Ingonish magnetic anomaly has been resolved into a number of smaller anomalies, some of which are elliptical and some of which are linear (Fig. 77
4.2). The latter appear to connect with linear trends that are the offshore continuation of the onshore Bras d’Or terrane linear anomalies. Farther south, a series of linear trends extend from the Bras d’Or and Mira terranes across the Sydney Basin toward
Newfoundland and are much more apparent on the first derivative map (Fig. 4.2) than on the total field map (Fig. 4.1). These moderate to strong positive elongate anomalies are broken up into smaller sections and appear to merge with the offshore circular and elliptical anomalies that characterize the Burgeo subzone.
Anomalies farther north in the Cabot Strait are also better defined, including the curvilinear anomaly extending from Aspy Bay across the strait to the southern part of the
Notre Dame subzone in Newfoundland. However, the connection of this anomaly with those onshore in northeastern Cape Breton Island is more tenuous due to the presence of strong east-southeast-trending anomalies that characterize the northeastern part of the
Aspy terrane south of Aspy Bay.
The linear anomaly extending from the northeastern tip of Cape Breton Island through St. Paul Island is more prominent on the first derivative map, but broader, and may extend a few kilometres northeast of St. Paul Island where it appears to terminate.
This anomaly supports the correlation between rocks on St. Paul Island and the Money
Point peninsula as proposed by Lin (1994) based on his mapping of St. Paul Island.
The large northeast-trending elliptical anomaly in the Cabot Strait has developed a positive rim and negative core and may consist of two separate but overlapping anomalies. This halo effect is typical of granitic plutons and their adjacent contact metamorphic aureoles (e.g., Cook et al. 2007). The halo effect is also displayed by the small circular body to the east, now a much more prominent feature than on Figure 4.1.
The linear anomaly extending from the Port-aux-Basques subzone is also better resolved 78 as a separate feature on the first derivative map and appears to extend along the northwestern edge of the elliptical anomaly.
Onshore in Newfoundland, the Port-aux-Basques subzone shows linear and patchy anomalies similar to those in the correlative Meelpaeg subzone to the northeast.
The Burgeo subzone contains abundant irregularly shaped anomalies with the halo effect characteristic of plutons as noted above. They continue into the offshore with no loss in magnitude, indicating that they are near-surface features.
Strong positive and negative anomalies characterize the Notre Dame subzone, and the western part of the Humber Zone north of the Bay St. George sub-basin (Fig. 4.2).
The central and northwestern areas of Humber Zone on the map show strong positive and negative anomalies with an irregular pattern. In the St. George’s Bay, the moderately intense positive anomaly located in the southwest has intensified and part of it appears to have the characteristics of a pluton with a contact metamorphic aureole. The anomaly of stronger intensity in the northern part of the bay has also intensified on the first derivative map and clearly continues into the onshore.
4.2.3 Second Vertical Derivative
The second derivative map (Fig 4.3) provides further resolution of some of the magnetic anomalies seen on the first derivative map, but obscures others. Artefacts are prominent in the image, caused by noise from short wavelength anomalies during data acquisition and gridding; however, the prominent anomalies caused by geologic sources remain clearly visible. On Cape Breton Island, the boundary between the Mira and Bras d’Or terranes is seen to coincide with a subtle change in magnetic trends from northeast in the Bras d’Or terrane to more easterly in the Mira terrane. The differences in anomaly 79 patterns in the Bras d’Or and Aspy terranes and Blair River Inlier are less apparent than on the first derivative map. However, the anomalies trending east-southeast in the area of the Aspy terrane south of Aspy Bay are accentuated. In the offshore, the anomalies forming the IMA have become further resolved into separate anomalies, and their link back to the eastern Bras d’Or terrane is even more apparent than on the first derivative map, as is their continuity with segmented linear anomalies that appear to extend across the northern part of the Sydney Basin to the offshore part of the Burgeo subzone. The large linear anomaly in the Cabot Strait remains detectable, but its connection to the onshore in Aspy Bay is less pronounced, although its continuation to the northeast into the Notre Dame subzone adjacent to the Cape Ray Fault remains clear. The large elliptical anomaly in the Cabot Strait has been accentuated, as has the smaller circular anomaly to the east, and halo effects are apparent. Linear anomalies in the Port-aux-
Basques subzone continue into the offshore north of the circular and large elliptical anomalies, but appear to be somewhat oblique to and perhaps cut off by the southern
Notre Dame zone anomaly.
The second derivative map clearly shows a strong anomaly signal originating from the area north of the Port au Port Peninsula, and extending out into the southwestern
Bay of St. George sub-basin. A second positive anomaly appears to originate from the
Indian Head Complex northeastern region of the bay passing below the sedimentary units on the eastern shore of St. George’s Bay, and then the anomaly turns west into the centre of the Bay of St. George sub-basin where the anomaly loses intensity, likely related to the thick sedimentary cover in the basin.
80
4.2.4 Downward Continuation
Downward continuing the magnetic data converts the data to values similar to those that would have been recorded if they were collected at a deeper level, closer to the anomaly sources (Sharma 1997). If downward continuation occurs to depths greater than the anomaly source, its signal will be reduced. Downward continuation can also amplify noise and artefacts present in the data (Sharma 1997). In this study, a downward continuation filter of 400 m below sea level (0 m) was used because it is the greatest depth for downward continuation to get close enough to near-surface sources without generating excessive noise and artefacts. The resulting map (Fig. 4.4) differs only slightly from the original total field (TMF) anomaly map (Fig. 4.1) but sharpens many of the deeper anomalies as a result of being closer to their sources. Some of the magnetic signals from near-surface sources are eliminated while deeper signals are amplified in some areas, especially in areas of Carboniferous cover. The large elongate anomalies of the eastern Bras d’Or terrane are enhanced by the downward continuation, indicating that their sources extend to depth.
The Aspy terrane and the Blair River Inlier exhibit most of the same anomalies as in the TMF anomaly map, but with greater intensity on many of the anomalies as downward continuation gets closer to their sources. The IMA has the same shape as on the TMF anomaly map, with enhanced resolution on the edges of the anomaly and with greater positive anomaly intensity. The elongate elliptical anomaly in the Cabot Strait has the similar positive magnetic signature with a small increase in intensity compared to the
TMF anomaly map. The edges of the small circular contact aureole in the Cabot Strait and the ones near the southeastern Exploit and Gander subzone coastline have undergone minor intensification; these anomalies are located from 0 m to depth greater than 400 m 81 below sea level and buried under several thousand meters of Carboniferous units
(Langdon and Hall 1994). The same anomalies are visible in the Notre Dame subzone,
Humber Zone, and the St. George’s Bay as in the TMF anomaly map but signals originate closer to the source resulting in higher resolution of the anomalies.
4.3 Gravity Maps
The gravity anomaly map (Fig. 4.5) displays free-air anomalies in offshore areas and Bouguer anomalies onshore. The northeastern Bras d’Or terrane is characterized by positive gravity anomalies of 0 to 40 mGal, but the southern part lacks those anomalies and little distinction is apparent between Bras d’Or and Mira terranes. The southern and western parts of the Aspy terrane contain weak positive gravity anomalies (~20 mGal).
Anomalies in the northern part of the Aspy terrane and in the Blair River Inlier range between 0 and 10 mGal. In the offshore, the area of the IMA displays only weak gravity anomalies, up to 10 mGal, in contrast to its strong magnetic signature (Fig. 4.1).
Prominent lows of -20 to -100 mGal characterize the Magdalen Basin in the
Cabot Strait area, coinciding with an area of thick evaporites (Fig. 1.4) and salt tectonics
(Langdon and Hall 1994). The Sydney Basin also shows areas of low gravity anomalies
(0 to -80 mGal), one in the Cabot Strait area and one farther south off shore from the
Mira terrane. The trace of the deeper Laurentian Channel (Fig 1.5) can be seen trending southeast between southwestern Newfoundland and Cape Breton Island. This effect is caused by the lower density of the water in the deeper Laurentian Channel in comparison to the higher density sediment deposits located on the edges of the channel in adjacent shallower areas. In Newfoundland, strong positive gravity anomalies (0 to 40 mGal) 82 characterize the Notre Dame subzone. A small anomaly (10-20 mGal) is associated with the northwestern coastline of St. George’s Bay.
The horizontal gradient of gravity map (Fig. 4.6) emphasizes the edges of gravity anomalies. The greater the difference in density values of two units in contact the greater the anomaly will be on the horizontal gradient map. The edges of the Laurentian Channel noted above are very prominent on the horizontal gradient map. A strong linear anomaly is associated with the Aspy and Bras d’Or terrane boundary, and appears to continue offshore as a northeast-trending feature, although its linearity suggests that it may be in part an artefact of data correction (Fig 3.1). Three linear anomalies are apparent in the
Cabot Strait area and appear to coincide with fault zones and/or terrane boundaries identified onshore. The western and eastern edges of the Notre Dame subzone are marked by strong linear anomalies. The St. George’s Bay area in the Humber Zone also shows strong linear anomalies, although the pattern should be viewed with caution because gravity data are sparse in some of that area (Fig. 3.1).
4.4 Seismic Data
4.4.1 Lithoprobe/Frontier Geoscience Seismic Lines 86-4 and 86-5A
Deep seismic reflection lines 86-4 and 86-5A cross the study area and paper copies were examined as part of this study. Interpretations of those lines by Marillier et al. (1989), Loncarevic et al. (1989), and Pascucci et al. (2000) were also utilized. These lines provide data through the entire crust down to the Mohorovicic Discontinuity
(Moho), and in some cases below (about 15 seconds of two-way travel time). Marillier et al. (1989) recognized three different types of lower crustal blocks on these profiles, 83 which they termed Grenville, Central, and Avalon. At surface they correlated these blocks with the Humber, Gander, and Avalon zones.
Line 86-4 extends through the Cabot Strait from St. George’s Bay to the northern edge of the Sydney Basin, close to southwestern Newfoundland (Fig. 3.3). Marillier et al. (1989) identified Grenvillian basement along most of the profile, thinning to the south where it is in contact with the thicker crust of the Central block. The Central block is characterized by strong reflectors at a depth equivalent to 9-12 seconds of two-way travel time, whereas the deep crust under the Grenville block has fewer strong reflectors. The middle and upper crust in both blocks has few internal reflectors, and the boundary between the two blocks is inferred to dip to the south. Its position at surface corresponds approximately to the Cabot/Long Range Fault. The Bay St. George sub-basin is located in a south-dipping half-graben overlying an area of crustal thinning within the Grenville block. Using the average seismic velocity of 4.5 km/s provided by Marillier et al. (1989), the thickness of sediments in the basin is estimated at 5175 m. Marillier et al. (1989) did not subdivide the Carboniferous units on their interpretations of this profile.
Deep seismic line 86-5A extends from the Magdalen Basin through the Sydney
Basin offshore from eastern Cape Breton Island (Fig. 3.3). On this profile, Carboniferous sediment thickens to the south in the Sydney Basin, up to about 1.75 s TWTT. Two deeper basins extend to a depth of about 2.5 s TWTT, or about 5500-6000 m assuming an average seismic velocity of 4.5 km/s. These deeper basins are interpreted to have formed as half graben by Marillier et al. (1989). Two similar half-graben structures occur near the northern end of the profile, near the inferred contact between the Grenville (Humber
Zone) and Central (Gander Zone) crustal blocks. That boundary is inferred to be marked by a south-dipping fault in the pre-Carboniferous rocks, flanked on both north and south 84 by the two half-graben basins (Searston and Cape Ray grabens of Langdon and Hall
1994), and by a shallowing of the depth to Moho. A second vertical(?) fault appears to originate beneath the more northerly (and deeper) of the two half-graben in the southern part of the Sydney Basin. Subtle differences in deep crustal reflectors occur across that inferred vertical fault, interpreted to be the boundary between the Central block and
Avalon block according to Marillier et al. (1989), or between Bras d’Or and Mira
(Avalon) according to Loncarevic et al. (1989). Marillier et al. (1989) did not attempt to subdivide the Carboniferous rocks on their line-drawing interpretation.
Pascucci et al. (2000) made a more detailed interpretation of the upper part of line
86-5 (to a depth of about 8 s two-way travel time), in combination with industry seismic data in the area and drill hole data. They inferred the presence of a series of south- dipping half graben, with Horton Group overlying undifferentiated basement in the graben, Windsor and Mabou groups overlying both graben and adjacent basement blocks, and Morien and Pictou groups covering the entire basin to a maximum depth of 2 s of two-way travel time.
4.4.2 Industry Seismic Lines – Cabot Strait and Sydney Basin
A number of industry seismic lines cross the Cabot Strait area, and the interpretation of those lines formed the basis of the papers by Langdon and Hall (1994) and Pascucci et al. (2000). Those studies focused on the Carboniferous units and did not attempt to identify the underlying pre-Carboniferous rocks. However, the interpretations provide reliable constraints on the thickness of the Carboniferous units, useful in the forward modeling process. 85
Sediment thickness in the Cabot Strait is greatest in the Cape Ray and Searston graben. The lack of salt structures east of the inferred trace of the Cabot fault on these seismic line interpretations suggests that the lower Windsor-Codroy Group is missing from the deeper basin fill. The Searston graben is mappable from seismic lines, recognized by the continuous, medium to high frequency parallel reflections (Langdon and Hall 1994). The graben appears to have synclinal strata in some sections with complex fault and fold patterns, particularly near St. Paul Island. Windsor salt structures appear to onlap the Horton Group which is dipping west away from the Cabot fault. The many salt structures in the Searston Graben are indicative of a thick Windsor Group
(Langdon and Hall (1994).
4.4.3 Industry Seismic Lines - St. George’s Bay
The sedimentary successions of the Bay St. George sub-basin were interpreted by
Langdon (1996) as the Codroy and Barachois groups, visible on seismic lines MAQ-017 and MAQ-012 (Fig. 3.3). The dimensions of the Bay St. George sub-basin, the shape of the coastline, and the structure of older rock units in the central and eastern Port au Port
Peninsula are controlled by several northeast trending faults with Carboniferous movement (Williams 1985; Waldron and Stockmal 1991; Langdon and Hall 1994). Lines
TAJ009 and TAJ010 in the outer part of St. George’s Bay show the St. George’s Bay fault system; the section that has been referred to in the past as the Mid-Bay fault is really the hanging wall cutoff of the westerly dipping displacement zone (Langdon 1996). On line TAJ009 the St. George’s Bay fault reaches the top of the Carboniferous section and becomes part of the southerly extent of the major normal fault that marks the eastern shoreline of St. George’s Bay (Langdon 1996). The Bay St. George sub-basin contains 86 salt swells and ridges at the centre and the edges of the basin. The swells and ridges have northeast trends, parallel or subparallel to the major faults.
4.5 Physical Property Data
4.5.1 Pre-Carboniferous Rocks – Cape Breton Island
The onshore magnetic susceptibility data were assembled for measured samples representing pre-Carboniferous rock units in the eastern parts of the Bras d’Or and Aspy terranes and Blair River Inlier of Cape Breton Island (Appendix A). Ranges and average k data for the major units are summarized in Appendix B. Mafic dykes were excluded from the data base as they occur in all units and are generally less than 1-2 m in width; hence, they are unlikely to be a significant component of the overall magnetic signature of the host unit. Density estimates for the pre-Carboniferous units were taken from Tenzer et al. (2011), except for units in the Boisdale Hills which have density data measured by King (2002).
Because of wide variations in the rock types present, the units of the Bras d’Or terrane show a wide range in measured magnetic susceptibility (Appendix B). Assuming that the sample collection is reasonably representative of the relative proportions of rock types in the units, the average values may be representative of the unit as a whole. On that basis, the metasedimentary units of both the George River Metamorphic Suite
(McMillan Flowage Formation, Barachois River Formation, Benacadie Pond Formation) and the Bras d’Or Gneiss (Kellys Mountain Gneiss, Frenchvale Road Metamorphic Suite) have relatively low, but highly variable, susceptibility. Barachois River Formation is the highest with an average k of 4.46 x 10-3 SI. Density values measured by King (2002) in 87 the Frenchvale Road Metamorphic Suite and Benacadie Pond Formation also show a range, but the average values are similar at 2660 and 2780 kg/m3, respectively).
The Cambrian sedimentary and volcanic rocks of the Bourinot belt have similar average values as the older metasedimentary units, with higher values attributed to mafic volcanic components of the suite. The Ordovician-Silurian Clyburn Brook Formation has low average susceptibility (average 0.95 x 10-3 SI) whereas the Devonian Ingonish Island
Rhyolite has a much wider range and higher average (8.36 x 10-3 SI).
The Neoproterozoic plutons of the Bras d’Or terrane show a wide range in susceptibility values. The highest average values are in the Timber Lake Dioritic Suite,
(17.83 x 10-3 SI), Indian Brook Granodiorite (14.99 x 10-3 SI), Wreck Cove Dioritic Suite
(10.37 x 10-3 SI), and Kellys Mountain Diorite (8.96 x 10-3 SI). The Cambrian Birch
Plain Granite shows a higher average (12.07 x 10-3 SI) than the Kellys Mountain Granite
(3.36 x 10-3 SI) and Mount Cameron Syenogranite (2.64 x 10-3 SI) of similar age. The
Devonian Cameron Brook Granodiorite has a relatively low k of 3.48 x 10-3 SI
(Appendix B). Density values for these plutons were selected from Tenzer et al. (2011), except for Boisdale Hills and Shunacadie plutons for which King (2002) reported averages of 2.82 and 2.71 g/cm3, respectively.
In the Aspy terrane, susceptibility values are generally lower than in Bras d’Or terrane, with averages of 3.58, 1.61, and 2.73 x 10-3 SI for the Cape North, Money Point, and Sarach Brook groups, respectively (Appendix B). Plutonic units generally have susceptibilities less than 1 x 10-3 SI.
Units in the Blair River Inlier have average susceptibility values of 12.51 x 10-3 SI for gneissic units and 6.00 x 10-3 SI for plutonic units. One sample from the Lowland
Cove Formation has susceptibility of 0.18 x 10-3 SI. 88
4.5.2 Pre-Carboniferous Rocks – Newfoundland
Few susceptibility and density measurements were found in the published literature for pre-Carboniferous units in southwestern Newfoundland. Miller et al.
(1990) suggested average densities of 2830 kg/m3 for the Steel Mountain Inlier and 2680 kg/m3 for the Indian Head Complex. Citing work by Peavy (1985), they reported wide variations in susceptibility values for pre-Carboniferous rock units in the area, from near
0 to >75 x 10-3 SI units. They noted that Peavy’s data indicate that the Indian Head
Complex has relatively low values (<1.26 x 10-3 SI units), but higher k values might be expected from gabbroic rocks in the complex. The high values in the range reported by
Peavy (1985) are from the Steel Mountain Inlier and reflect the presence of magnetite- rich layers and lenses. They noted that Spector (1969) estimated that basement susceptibilities in the area range from 0.8 to 4.3 x 10-3 SI units, with an average of about
2.24, based on the aeromagnetic maps. A study by Watts (1972) in the Magdalen Basin assigned susceptibility values of 1.3 to 1.6 x 10-3 SI units to pre-Carboniferous units.
Wiseman and Miller (1994) reported measured data for both density and susceptibility in samples from the Bay du Nord Group and Burgeo Intrusive Suite. The mean values for density are 2.68 and 2.64 g/cm3, respectively, and the mean susceptibility values are 2.5 and 18.4 x 10-3 SI units. They also reported average density of 2.74 g/cm3 and average susceptibility of 31 x 10-3 SI units for ophiolitic rocks in the
Dunnage (Notre Dame) Zone.
4.5.3 Carboniferous Units – Cape Breton Island
Measured density and susceptibility data for Carboniferous units in western Cape
Breton Island reported by Cook et al. (2007) are 2.29, 2.35, 2.47, 2.59, and 2.54 g/cm3 for 89 the Pictou, Cumberland (Morien), Mabou, Windsor, and Horton groups, respectively.
Average susceptibilities for these same units are 0.08, 0.17, 0.17, 0.07 from Cook et al.
(2007), and 0.15 x 10-3 SI units from King (2002), respectively.
4.5.4 Carboniferous Units – Newfoundland
Miller et al. (1990) reported average density values of 2.63, 2.47, and 2.54 for the
Anguille, Codroy, and Barachois formations in the Bay St. George sub-basin, using data from Peavy (1985) and Kilfoil (1988). They also presented data for halite (2.18 g/cm3), gypsum (2.28 g/cm3), and anhydrite (2.97 g/cm3) from drill holes in the Codroy
Formation. Miller et al. (1990) and Wiseman and Miller (1994) suggested that magnetic susceptibility is so low in the Carboniferous units that it is essentially 0.
4.6 Potential Field Models
4.6.1 Model Parameters
In the 2D forward modeling process, the edges and outlines of an anomalous magnetic or gravity body are estimated using seismic constraints where available, and susceptibility and density parameters assigned. The goal is to generate magnetic and gravity anomaly profiles which match the observed profiles. The process involves using trial and error adjustments to geologically satisfy model parameters to make them agree with the data in the selected magnetic and gravity profile (Sharma 1997). The density and magnetic susceptibility values which work best in the model profiles of the present study are summarized in Figure 4.7. On some models, basement sources represent rocks which are inferred to be adjacent to the model profile but which are not included in the modeled anomalies. 90
4.6.2 Profile 1
Profile 1 is 60 km long and trends NW-SE through the Cabot Strait, extending from the Magdalen Basin on the northwest to the Sydney Basin in the southeast (Fig.
4.8). It crosses two linear magnetic anomalies continuing offshore from the Notre Dame and Port-aux-Basques subzones, and a circular halo anomaly to the south (Fig. 4.8).
These three magnetic features are evident in central and southeastern parts of the magnetic anomaly profile (Fig. 4.9). The model for this profile shows three
Carboniferous layers corresponding to the Pictou/Morien, Windsor, and Horton groups
(Fig. 4.7), based on interpretations of seismic reflection profiles in the area (Langdon and
Hall 1994). The central magnetic anomaly is inferred to be the result of three basement sources, BS1, BS2 and BS3. Source BS2 is inferred to be plutonic and intrudes BS3 in two locations. These intrusions are represented by the two westernmost anomaly peaks in the profile. The lower magnitude but wider anomaly to the east represents the smaller magnetic halo in the Cabot Strait as shown in the model by basement source BS1, which is inferred to intrude BS3. The contact between BS3 and GB (Grenville basement) is suggested to be a vertical fault, interpreted by Langdon and Hall (1994) on Line 81-1103 as the Cabot Fault Zone.
The positive gravity anomaly in the profile is attributed to a combination of BS1,
BS2, and BS3. The basement “low” east of the inferred Cabot Fault Zone in BS3 corresponds to the Cape Ray Graben as interpreted on seismic profiles by Langdon and
Hall (1994).
Thickness of sedimentary layer 1 ranges from 300 m to 2.65 km along the profile and thickens to into the Magdalen Basin to the north. Layer 2 is thicker, varying between
1800 m and 5700 m. Layer 3 occurs only in the Cape Ray Graben where it has a 91 maximum thickness of 700 m on the model, consistent with the seismic interpretation of
Langdon and Hall (1994). A fault appears to cut through the sedimentary units in the western part of the model, interpreted to be the continuation of the Hollow Fault by
Langdon and Hall (1994) but all potentially the St. George’s Bay Fault (Fig. 2.3). The
BS2 basement sources occur at depths of 6.8 to 8.0 km below the surface, whereas the top of basement source BS3 is at depths ranging from 4.0 to 6.3 km below the surface.
Basement source BS1 is deepest, at a depth of 7.7 to 8.6 km. North of the Cabot Fault, inferred Grenville basement (GB) is at a depth of 5.4 to 5.6 km below sea level.
4.6.3 Profile 2
Profile 2 is about 67 km long and also crosses from the Magdalen Basin to the
Sydney Basin, including both linear magnetic anomalies in the central part of the Cabot
Strait (Fig. 4.8). It also includes the northeastern part of the large northeast-trending elliptical anomaly to the south (Fig. 4.8). Overall, the magnetic signal is higher over the southern (Sydney Basin) part of the profile than the northern (Magdalen Basin) part (Fig.
4.10). In the model, the basement in the central part of the profile is composed of BS1,
BS2, and BS3, and the Cape Ray graben continues into the area. The BS1 and BS2 sources are also interpreted to be intrusions into basement BS3. Basement source B2 is related to the two magnetic peaks in the central part of the profile that coincide with the linear magnetic anomalies extending from southwestern Newfoundland towards Cape
Breton Island. The large anomaly in the southern part of the profile is caused by source
B1, also interpreted to be plutonic because of the halo effect seen on the map and profile, and a body similar to but separate from the BS1 source in profile 1 because in plan view their magnetic anomalies are separate (e.g., Fig. 4.2). 92
The positive gravity anomaly in the profile is attributed to basement sources BS2 and BS3, whereas the relative gravity low in the southeastern part of the profile is related to source BS1, as also seen on profile 1 (Figs. 4.9, 4.10). Sediment thickens to 7 km over basement sources BS1 and BS3 in the central part of the profile. Layer 1 varies in thickness from 500 m to 3.3 km and layer 2 varies in thickness from 1.0 km to 5.3 km.
Layer 3 is located only in the Cape Ray graben and has an approximate maximum thickness of 950 m.
In the Magdalen Basin (northwestern part of the profile), the depth to the top of the underlying Grenville basement source (GB) ranges from 4.6 to 5.2 km. . At the southeastern part of the model, BS4 is inferred to be present, as also shown on Figure 4.9 and discussed below in more detail, as this source is not directly part of the modeled profile.
4.6.4 Profile 3
Profile 3 is about 79 km long and crosses St. Paul Island, the linear magnetic anomaly to the southeast, the southwestern part of the large elliptical halo anomaly, and a linear anomaly northeast of the Ingonish magnetic anomaly (Fig. 4.8). This model was the most difficult to construct, and a good match was not achieved between observed and calculated anomalies.
In the model profile, layer 1 varies in thickness between 0.4 and 1.4 km, and thins above the interpreted Cape Ray graben located above basement source BS3. As on profiles 1 and 2, the linear magnetic anomalies in the central part of profile 3 are associated with basement sources BS2, and the elliptical halo magnetic anomaly to the southeast is associated with basement source BS1, which is also responsible for the 93 negative gravity anomaly in this part of the profile. These basement sources are at a similar depth as on profiles 1 and 2, although basement source BS3 is at a shallower depth between 2.4 and 5.4 km below sea level. The maximum sediment thickness on the model is ~5.7 km in the central part of the profile, and the total thickness of sedimentary layers decreases toward the south.
Unlike profiles 1 and 2, profile 3 crosses onto inferred basement source BS4, in an area associated with a positive gravity anomaly but a negative magnetic anomaly, an effect achieved on the model in part by decreasing sediment thickness.
To explain St. Paul Island, basement source BS5 is brought to the surface in a schematic representation of a positive flower (Fig. 4.11). Source BS5 represents the rocks on St. Paul Island as discussed in Chapter 5.
Total sedimentary thickness increases to the north into the Magdalen Basin, especially the thickness of layer 2. Depth to the top of the underlying Grenville basement source (GB) varies from about 1.3 to over 4.0 km with halite present in layer 2 west of the Cabot Fault.
4.6.5 Profile 4
Profile 4 is 60 km long and extends from Aspy Bay southeast across the Ingonish magnetic anomaly (Fig. 4.12). On this model (Fig. 4.13), the thickness of layer 1 ranges from 1.0 to 3.0 km. Layer 2 varies from 480 m to 3.4 km, with the thickest part at the northwestern end of the profile. This area appears to be the Cape Ray graben as interpreted by Langdon and Hall (1994) on seismic Line 81-1121.
In the northwestern part of profile 4, the basement sources are interpreted to be
BS2 and BS3, as seen on models 1, 2, and 3, and are located at 6.5 to 7.8 km below sea 94 level in what is interpreted to be the continuation of the Cape Ray graben. An additional basement source, BS7, not seen on profiles 1, 2, and 3, is in likely faulted with
BS3 on the southeast, and underlain by another basement source, BS8. Basement source
BS4 appears again to the southeast, flanked by BS6 (Fig. 4.13). The basement sources responsible for the Ingonish Magnetic Anomaly are BS7, BS8, and BS4 in that order from northeast to southwest. Basement source BS7 is located at 5.4 to 6.4 km below sea level and is about 13 km wide. Basement source BS8 is about 10 km wide and is part of the basement at the centre of Profile 4, located deeper than BS8 at 6.2 to 6.6 km below sea level. Source BS4 makes up the southeastern edge of the basement sources modeled to be responsible for the IMA. It has a width of about 24 km, and is located at 5-6 km below sea level. BS4 is also inferred to be responsible for positive magnetic anomalies and gravity lows at the southeastern ends of profiles 2 and 3 (Figs. 4.10, 11). Basement source BS6 forms the basement at the edge of the model and hence its properties are not well constrained. Its top is at a depth of 5.4 to 6 km below sea level (Fig. 4.13).
4.6.6. Profile 5
Profile 5 is 52 km long and extends northeast from the Kellys Mountain area to cross profile 4 at right angles (Fig. 4.12). Total thickness of layers 1, 2, and 3 is a maximum (almost 6 km) in the central part of the model and then thins abruptly to about
3 km at the northeastern end. Relative thicknesses of individual layers 1, 2, and 3 do not vary significantly in this model. The basement sources responsible for the IMA on this profile are BS4 and BS8 (Fig. 4.14). BS4 underlies over 40 km of the profile and its top is located at depth of 4 to 6.2 km below sea level. Based on the model BS4 appears to be the southeastern component of the IMA. BS8 is 16 km wide with its top at 3.4 to 6.4 km 95 below the surface. The high positive magnetic anomaly high on the profile is generated in the northeastern part of BS4 near the contact area with BS8. A positive gravity anomaly occurs closer to the contact between sources BS4 and BS8. Source BS4 is also inferred to be present in the northeastern part of the model based on constraints from models 2 and 3.
4.6.7 Profile 6
Profile 6 is located in St. George’s Bay adjacent to southwestern Newfoundland
(Fig. 4.15). The modeled part of the profile is only 18 km long (Fig. 4.16) but the geological units are extended to the northwest and southeast based on seismic profile interpretations in the area (Langdon and Hall 1994). Layer 1 (Barachois Group) extends across the profile; thickness on the unit varies from 300 m to 3 km (Fig. 4.16). Layer 2
(Codroy Group) varies in thickness from 2 to 3.8 km; the thickest part is located in the southern part of the line where salt appears to be present, salt is also interpreted to be present on the western part of profile 6, consistent with seismic interpretations of line
MAQ-017 by Langdon and Hall (1994). The Anguille Group is not present on the model, consistent with previous interpretations by both Langdon and Hall (1994) and Miller et al. (1990). The gravity lows on either side of the profile appear to be caused by the presence of the salt. The source of the magnetic and gravity anomalies in the central part of the profile is modeled as Grenville basement (GB), and is located 4.3 to 4.8 km below sea level. 96
Fig. 4.1 Total magnetic field anomaly map of the study area produced during this study as described in Chapter 3. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) for reference on subsequent figures. 97
Fig. 4.2 First derivative of the total magnetic field anomaly map produced in the present study as described in Chapter 3. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) from Figure 4.1.
98
Fig. 4.3 Second derivative of the total magnetic field anomaly map produced in the present study as described in Chapter 3. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) from Figure 4.1.
99
Fig. 4.4 Downward continuation by 400 m of the total magnetic field produced in the present study as described in Chapter 3. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) from Figure 4.1.
100
Fig. 4.5 Bouguer (onshore) and free-air (offshore) gravity anomaly map produced in the present study as described in Chapter 3. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) from Figure 4.1.
101
Fig. 4.6 Map showing calculated horizontal gradient of gravity anomaly data in Figure 4.5 with illumination at an azimuth of 315o. Overlay (white lines) shows main terrane/zone boundaries from Figures 2.1 and 2.2a, and location of the Ingonish magnetic anomaly (IMA) from Figure 4.1.
102
Fig. 4.7 Summary of values for density (ρ in kg/m3) and magnetic susceptibility (k in x10-3 SI units) used for units in models offshore from Cape Breton Island (CBI) and southwestern Newfoundland (NL). 103
Fig. 4.8 Enlargement of the Cabot Strait area from the first derivative map in Figure 4.2 showing the location of forward-modeling lines 1, 2, and 3. The numbers indicate the distance in km along the profiles for the edges of each anomaly.
104
Fig. 4.9 Model for profile 1 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Horton, Windsor, and Pictou/Morien groups, respectively, as described in the text. Pre-Carboniferous basement anomaly sources are summarized in Figure 4.7. 105
Fig.4.10 Model for profile 2 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Horton, Windsor, and Pictou/Morien groups, respectively, as described in the text. Pre-Carboniferous basement anomaly sources are summarized in Figure 4.7.
106
Fig.4.11 Model for profile 3 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Horton, Windsor, and Pictou/Morien groups, respectively, as described in the text. Pre-Carboniferous basement anomaly sources are summarized in Figure 4.7. 107
Fig. 4.12 Enlarged view of the area around the Ingonish magnetic anomaly from the first derivative of the total magnetic field anomaly map in Figure 4.2, showing the location of forward-modeling lines 4 and 5. The numbers indicate the distance in km along the profiles for the edges of each anomaly.
108
Fig. 4.13 Model for profile 4 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Horton, Windsor, and Pictou/Morien groups, respectively, as described in the text. Pre-Carboniferous basement anomaly sources are summarized in Figure 4.7. Vertical line on model indicates intersection with profile 5.
109
Fig. 4.14 Model for profile 5 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Horton, Windsor, and Pictou/Morien groups, respectively, as described in the text. Pre-Carboniferous basement anomaly sources are summarized in Figure 4.7. Vertical line on model indicates intersection with profile 4.
110
Fig 4.15 Enlargement of the St. Georges Bay area from the first derivative magnetic anomaly map in Figure 4.2, showing the location of forward-modeling profile 6.
111
Fig. 4.16 Model for profile 6 produced in GM-SYS as described in Chapter 3. Layers 3, 2, and 1 correspond to the Codroy (Windsor), and Barachois (Pictou/Morien) groups, respectively, as described in the text. GB is Grenvillian basement (Fig. 4.7). 112
5.0 Discussion
5.1 Geophysical Implications for Onshore Geology
Overlaying the major geological units shown on the simplified geological maps from Chapter 2 (Fig. 2.1, 2.2) on the various geophysical maps enables the interpretation of which geologic units are responsible for the observed anomaly signatures in onshore areas. However, at the scale of this work, only the larger units are discussed here.
5.1.1 Cape Breton Island
On the total magnetic field anomaly map for northeastern Cape Breton Island, strong positive magnetic anomalies (200-500 nT) are associated with the Indian Brook
Granodiorite, Birch Plain Granite, Wreck Cove Dioritic Suite, and Ingonish River
Tonalite (Fig. 5.1a), consistent with their high average magnetic susceptibilities
(Appendix B). Metamorphic units are associated with low magnetic signatures, again consistent with their measured susceptibilities. The strong anomaly apparently associated with plutonic rocks in the Middle Head area trends east-west and appears to connect with the Ingonish magnetic anomaly in the offshore. It is not clear if this anomaly is related to that associated with the Ingonish River Tonalite because the trend is disrupted by the intervening Ingonish Beach Gneiss which has a low magnetic signature associated with it. The dioritic rocks on Middle Head have been correlated with the Wreck Cove Dioritic
Suite on the basis of petrology (Raeside and Barr 1992).
The Boisdale Hills and Shunacadie plutons, which are dominated by intermediate-felsic rocks, are less magnetic, but still have a stronger signature than the associated Benacadie Pond formation, Frenchvale Road Metamorphic Suite, and 113
Bourinot belt. The intermediate-felsic Precambrian plutons (e.g. Cross Mountain
Granite), Cambrian plutons (Cape Smokey Granite, Kellys Mountain Granite, and Mount
Cameron Syenogranite), and Devonian plutons (Cameron Brook Granodiorite) also have lower magnetic signatures, again broadly consistent with their average susceptibility measurements (Appendix B).
On the first derivative map (Fig. 5.1b) the negative magnetic anomaly associated with the Clyburn Brook Formation and Cameron Brook Granodiorite trends into the offshore north of Middle Head. Ingonish Island shows up as a small magnetic high, consistent with the relatively high average susceptibility of the rhyolite (Appendix B), but it does not appear to link to a larger body in the offshore. In contrast, the Middle Head anomaly is accentuated on the first derivative map and appears to extend into the area of the Ingonish magnetic anomaly in the offshore. On the second derivative map (Fig.
5.1c), linear trends between the onshore magnetic units of the eastern Bras d’Or terrane into the offshore are even more apparent, and it seems likely that all of the pre-
Carboniferous units of the Bras d’Or terrane extend northeast into the offshore. In particular, the Wreck Cove Dioritic Suite and Indian Brook Granodiorite/Birch Plain
Granite appear to continue into the area of the Ingonish magnetic anomaly (Fig. 5.1c).
The northeastern Bras d’Or terrane is associated with a strong positive gravity anomaly (20-40 mGal) that does not extend far into the offshore in the Middle Head area
(Fig. 5.1d). It also does not extend into the Kellys Mountain and Boisdale Hills areas, indicating that its source is at depth under the terrane, and not likely to be directly related to units now exposed at surface. This anomaly may be associated with heavy deep crustal rocks which have been brought to shallower depths as Bras d’Or terrane was 114
thrust over Aspy terrane in the tectonic model of Barr et al. (1995). However the anomaly continues to the west into areas where Aspy terrane rocks are exposed at surface.
In the Aspy terrane, the total field magnetic anomaly map shows a large negative anomaly associated with the Black Brook Granitic Suite, Cheticamp Lake Gneiss, and
Park Spur Granite (Fig. 5.1a). These units all have low magnetic susceptibility
(Appendix B). Also included in the area of the negative anomaly are the Clyburn Brook
Formation and Cameron Brook Granodiorite, and the anomaly continues offshore where it abuts the Ingonish magnetic anomaly. Elsewhere in the Aspy terrane units assigned to the Cape North and Money Point groups tend to have low magnetic signatures with smaller areas of higher anomalies. This variability is consistent with the ranges of rock types and metamorphic grades in these units (Barr and Jamieson 1991; Raeside and Barr
1992) and wide variations in measured magnetic susceptibilities (Appendix A).
Weak linear anomalies in the Black Brook Granitic Suite also extend to the west into the Money Point Group and Glasgow Brook granodiorite. The linear features intensify on the first derivative map (Fig. 5.1b) indicating that they are caused by shallow features such as mafic dykes; however, no evidence for mafic dykes or faults was observed during field work in those areas (Yaowanoiyothin and Barr 1991).
The variability increases on the first and second derivative maps (Fig. 5.1b, c), which show a more detailed correlation between anomalies and unit in the northeastern
Aspy terrane.
The northeastern part of the Aspy terrane is characterized by a weaker gravity signature (0-10 mGal) in comparison to the neighbouring Bras d’Or terrane (Fig. 5.1d). 115
However, gravity anomalies are present in the southern and western parts of the terrane where Precambrian rocks outcrop at surface. The horizontal gradient (Fig. 5.1e) emphasizes the Wilkie Brook Fault separating the Aspy terrane and the Blair River Inlier, and the nearby and parallel Aspy fault. The horizontal gradient of gravity map also suggests the presence of a fault through the centre of the Aspy terrane and cutting the
Black Brook Granitic Suite before disappearing into the offshore (Fig. 5.1e). However, no evidence of this fault was found during field work in the area (Raeside and Barr
1992).
The Blair River Inlier is characterized by very strong positive anomalies (200-500 nT) on the total field anomaly map (Fig. 5.1a). The first and second derivative maps
(Fig. 5.1b, c) also display strong positive and negative surface anomalies in the Blair
River Inlier. The abrupt change in signal intensity at the Carboniferous contact suggests that a fault might be present trending east-west, with thick Carboniferous rocks in the area to the north. In contrast to its strong magnetic signal, the gravity anomalies associated with the Blair River Inlier are weak (0-10 mGal) (Fig. 5.1e).
5.1.2 Southwestern Newfoundland
The Burgeo subzone in southwestern Newfoundland shows several elliptical halo anomalies on the total field magnetic anomaly map (Fig. 5.2a) which are accentuated on the first derivative map (Fig. 5.2b). Such anomalies are characteristic of plutons and onshore plutons of that area clearly continue into the offshore. Especially notable are (1) the elliptical halo anomaly associated with the La Poile Granite part of the North Bay
Batholith which extends about 30 km into the offshore, and (2) overlapping elliptical halo 116
anomalies associated with the Burgeo Intrusive Suite which show that it is a composite body with separate plutons extending into the offshore about 20-30 km but not farther.
Anomalies associated with this plutonic suite continue east to the Grey River area and make it difficult to trace the eastward extent of the relatively small area of Silurian and older rocks located west of the intrusive suite and south of the Bay d’Est Fault Zone, or to infer how they might link to those of the Grey River area. A large elliptical anomaly in the adjacent offshore could indicate that the Wild Cove Granite is much larger than the small area exposed onshore, but that anomaly could also be related to one of the other plutonic units, in the area. More detailed maps and also the acquisition of susceptibility data would assist in the interpretation of this important area.
Low and relatively featureless magnetic signals are associated with the Exploits subzone to the north and west, although plutonic components can be discerned as having generally lower magnetism than associated stratified units of the Bay du Nord and
Harbour le Cou groups and equivalent units.
In contrast, the Port-aux-Basques subzone to the west of the Ile-aux-Morts Fault
Zone shows linear magnetic anomalies, with an especially prominent one that appears to be associated with the Margaree Orthogneiss (Fig. 5.2a). The outline of the magnetic anomaly becomes clearer on the first and second derivative maps (Fig. 5.2b, c), and is clearly cut off by the Silurian-Devonian North Bay Batholith. In contrast a negative anomaly appears to be associated with the Kelby Cove Orthogneiss.
The Meelpaeg subzone to the northeast shows magnetic signatures in the North
Bay Batholith similar to those in the Burgeo Intrusive Suite. The Gander Group shows stronger magnetic signals than the adjacent Bay du Nord Group-equivalent units. 117
The Notre Dame subzone displays distinctive magnetic character with many positive anomalies (200-500 nT) on the total magnetic field anomaly map (Fig. 5.2a), linked to ophiolitic and tonalitic arc rocks of the Lush’s Bight Oceanic Tract, Baie Verte
Oceanic Tract, and Notre Dame Arc. Younger (Silurian) plutonic units give variable signals from high to low, suggesting that they are compositionally varied. The main unit of metasedimentary rocks of the Dashwoods block shows a strong negative magnetic anomaly. A southern lobe assigned to that unit by Hibbard et al. (2006) has a strongly positive magnetic signature, more consistent with its designation as Notre Dame arc rocks (Colman-Sadd et al. 1990). A strong linear anomaly (400 nT) near the Cape Ray fault and extending offshore appears to be associated with the Cape Ray Igneous
Complex (granodioritic rocks).
The strong magnetic signature of the Notre Dame subzone ends abruptly at the
Cabot Fault and the edge of the onshore part of the St. George Bay sub-basin (Fig. 5.2a).
Farther north, the Grenvillian Steel Mountain Inlier has a prominent magnetic signature
(300-500 nT), further accentuated on the first and second derivative maps (Fig. 5.2b, c).
The smaller Indian Head Complex shows a similar signal (300-500 nT), similarly enhanced on the derivative maps. A large positive anomaly linked to the Steel Mountain
Inlier appears to extend under the onshore part of the St. George Bay sub-basin. It is abruptly cut-off by the St. George’s Bay Fault along the coastline and may not extend out under the bay. A strong magnetic signature (200-400 nT) appears to be associated with
Neoproterozoic-Ordovician sedimentary units (Table Head Group) at the northwestern side of St. George’s Bay. However, it is more likely that another ophiolite body is present under that area, comparable to the one onshore to the north. 118
The gravity anomaly map shows few significant anomalies other than in the Notre
Dame subzone (Fig. 5.2d). In the Port-aux-Basques subzone a positive gravity anomaly
(10 mGal) is associated with the Grand Bay Complex (Fig. 5.2b). A gravity low of -40 mGal in the Meelpaeg subzone suggests that the North Bay Batholith is thick. The strongest gravity anomaly signals (20-40 mGal) in the Notre Dame subzone do not appear to be linked to any particular unit In the Humber zone, a gravity anomaly of 20 mGal is associated with the Port-au-Port Peninsula, apparently in an area of mainly sedimentary units. The gravity anomaly suggests that unexposed higher density rocks occur at depth, possibly another ophiolite body as also suggested by the magnetic data as described above. The horizontal gradient of gravity anomalies shows strong gradients associated with the Cabot and Cape Ray faults and with the Red Indian Line (Fig. 5.2e).
5.2 Geophysical Implications for Offshore Geology
5.2.1 Major faults and terrane boundaries
Both Langdon and Hall (1994) and Pascucci et al. (2000) focused on
Carboniferous units and faults affecting Carboniferous rocks. They showed pre-
Carboniferous basement on their interpretations, but did not speculate on the nature of that basement. Because the Carboniferous units contribute little to the magnetic field signatures, those data have the potential to enable the interpretation of the pre-
Carboniferous units by comparison to the onshore areas where geophysical signatures can be linked to particular areas and in some cases to particular units. The offshore pre-
Carboniferous units would have thicker sediment accumulations above them than their 119
onshore equivalents, and thus Carboniferous units have greater influence on gravity anomalies in the offshore, especially in basins with thicker sequences.
Two of the best defined areas onshore in the study area are the Blair River Inlier and Humber Zone, both underlain by Grenvillian rocks with distinctive magnetic signatures (Fig. 5.3a). Onshore, the Wilkie Brook and Cabot faults mark the southeastern margins of these units, and those boundaries can be traced and connected on the total field anomaly and first and second derivative magnetic maps (Fig. 5.3a-c), more or less as interpreted by Langdon and Hall (1994), with the Searston graben to the northwest. In this interpretation, both the onshore part of the Bay St. George sub-basin and
Carboniferous rocks onshore in northernmost Cape Breton Island are part of this graben.
Also clear from the magnetic maps is the fact that the Notre Dame subzone does not extend far into the Cabot Strait, as indicated by a change in magnetic signatures. It is likely that the Cape Ray Fault merges with the Cabot Fault to cut off the Notre Dame subzone. The area south of the Cape Ray Fault and south of the Cabot Fault farther west is assigned to a composite terrane including rocks equivalent to the Aspy terrane onshore in Cape Breton Island and the Port-aux-Basques, Meelpaeg, and Exploits (including
Burgeo) subzones in southwestern Newfoundland (Fig. 5.4). This area includes St. Paul
Island (Fig. 5.3a). The source for the strong linear magnetic anomaly south of the merged Cape Ray and Cabot faults in the offshore is uncertain but could be an magnetic mafic orthogneissic unit such as the Margaree Orthogneiss, which displays a strong magnetic signature on shore in the Port-aux-Basques subzone (Fig. 5.2a-c). If so, the body and its host rocks are cut off by the Cape Ray Fault before reaching the shoreline.
Whatever the source of this strong linear anomaly, it appears to extend to Cape Breton 120
Island in Aspy Bay and may continue onshore under Carboniferous sedimentary rocks based on the continuity of the magnetic anomaly (Fig. 5.3a-c). Although no unit resembling the ca. 475 Ma tonalitic, dioritic, and granodioritic Margaree Orthogneiss
(Valverde-Vaquero et al. 2000) is exposed in the Aspy terrane (e.g., Lin et al. 2007), it could be beneath the younger rocks which characterize the exposed part of the terrane.
Although in the approximately appropriate location, the Glasgow Brook orthogneiss is granitic, not strongly magnetic (Appendix A), and, although undated, inferred to be
Silurian-Devonian (Lin et al. 2007). Whatever its source, the sharp northwestern edge of the linear anomaly suggests that it is likely to be bounded by a fault, which extends from the Cabot Fault through Aspy Bay to Cape Breton Island where it may merge with the
Aspy Fault to the southwest (Fig. 5.3a, b).
The linear anomaly associated with the Margaree Orthogneiss onshore in the Port- aux-Basques subzone appears to continue into the offshore and extend about half way across the Cabot Strait. Elliptical halo-type anomalies in the Cabot Strait are inferred to be Silurian-Devonian plutons such as the La Poile Batholith part of the North Bay
Granite, or units of the Burgeo Batholith. The Margaree Pluton in the western part of the
Aspy terrane may be an onshore example in Cape Breton Island, where it has a relatively strong magnetic signature. It is K-spar megacrystic like many components of the North
Bay and Burgeo granitic suites, and although not well dated, it is also likely of Devonian age. The Black Brook Granitic Suite may be equivalent to the much less magnetic muscovite-biotite granite plutons in the North Bay and Burgeo suites.
The magnetic and gravity maps clearly point to the boundary between Aspy and
Bras d’Or terranes being located in the Middle Head area, placing Clyburn Brook 121
Formation and the Cameron Brook Granodiorite in Aspy terrane (Fig. 5.4). Bras d’Or terrane units can be traced into the Ingonish magnetic anomaly and resolved somewhat
(see next section), indicating that the terrane boundary extends along the northern margin of that feature and then under the Sydney Basin toward the south coast of Newfoundland.
It is difficult to trace it onshore into southern Newfoundland because of the abundant plutons in the offshore. However, the elliptical shapes of plutons in the offshore extension of the Burgeo Batholith change to more linear shapes typical of Bras d’Or terrane units in the area south of the Grey River Enclave, suggesting that is may be Bras d’Or terrane. This interpretation leaves the Silurian La Poile Group and associated older units in the Aspy terrane, but such rocks also occur in the western part of the Aspy terrane (Fig. 2.1).
The position of the boundary between the Bras d’Or terrane and Mira to the south is not really addressed by this study, so the previous interpretations of Loncarevic et al.
(1989) and Barr et al. (1998) are followed. This location is marked by subtle changes in magnetic signature which are most apparent on the second derivative map (Fig. 5.3c).
5.2.2 Interpretation of basement units on profile models
Models derived for magnetic and gravity anomalies on profiles 1, 2, and 3, as well as profile 6 in St. George’s Bay, all show Grenville basement (GB) northwest of the inferred location of the Cabot Fault (Figs. 4.9 – 11, 16). In the models, GB is assigned a density of 2875 kg/m3 and magnetic susceptibility of 7.33 x 10-3 SI units (Fig. 4.7), consistent with the rock types likely to be present based on exposed units in the Humber
Zone and Blair River Inlier. Southeast of the Cabot Fault, BS3 is the dominant basement 122
source, with a density of 2850 kg/m3 and susceptibility of 6.50 x 10-3 SI units. The density values are typical of metamorphic rocks (Tenzer et al. 2011), whereas the susceptibility is based on measured values in metamorphic rocks of the Cape North and
Money Point groups (Appendices A, B). This basement source broadly represents the metamorphic rocks (both metasedimentary and meta-igneous) of the Exploits, Port-aux-
Basques, and Meelpaeg subzones in Newfoundland and the Aspy terrane of Cape Breton
Island.
However, on profile 3 the model required a modified version of the BS3 basement source, termed BS5 (Fig. 4.7). BS5 with density 2805 kg/m3 and susceptibility 1.61 x 10-
3 SI units represents the rocks of the Money Point Group exposed on St. Paul Island. The poor match between observed and calculated anomalies in this part of profile 3 probably reflects the complexity of the geology in a positive flower structure (seismic interpretation of Langdon and Hall 1994) in which the details cannot be resolved at the scale of the modeling in GM-SYS. The lack of gravity data for St. Paul Island and the nearby surrounding area make it impossible to constrain and reduce gravity error in profile 3.
Plutonic units on these models include BS1 and BS2. BS1 with density of 2900 kg/m3 and susceptibility of 18.35 x 10-3 SI units is considered to represent plutons equivalent to components of the Burgeo Batholith which exhibit halo anomalies of similar size and shape onshore in southwestern Newfoundland. BS2 with higher density
(2960 kg/m3) and susceptibility (18.35 x 10-3 SI units) is interpreted to be the more mafic and deformed plutonic units of the Margaree Orthogneiss. These plutonic sources intruded BS3 basement rock forming the strong linear (BS2) and halo-like (BS1) 123
magnetic anomalies in the Cabot Strait from southwestern Newfoundland to the Aspy terrane in Cape Breton Island (Fig. 5.3b, c).
The boundary between BS3 and BS4 on the models for profiles 1, 2, and 3 represents the terrane boundary between Aspy/Port-aux-Basques/Meelpaeg/Exploits terrane and the Bras d’Or terrane to the southeast (Fig. 5.4). Basement source BS4 is probably a composite basement that is dominated by plutonic rocks but may also include metasedimentary rocks such as the McMillan Flowage Formation (= 2810 kg/m3; k =
2.10 x 10-3 SI units) and Kellys Mountain Gneiss (= 2810 kg/m3; k = 3.47 x 10-3 SI units). In the models, it has been assigned a density of 2940 kg/m3 and susceptibility of
8.96 x 10-3 SI units, similar to measured values in Kellys Mountain Diorite and Indian
Brook Granodiorite.
Based on the first and second derivative maps, the Ingonish magnetic anomaly, which appears as a single anomaly on the total field magnetic map, is resolved into several smaller anomalies. These separate anomalies can be linked to units exposed in the adjacent Bras d’Or terrane, using the second derivative map (Fig. 5.3c) and measured susceptibility data (Appendix B). On models generated for profiles 4 and 5, basement sources BS4, BS7, and BS8 are linked to the IMA (Figs. 4.13, 4.14). As noted above,
BS4 has density and susceptibility consistent with various plutonic units of the Bras d’Or terrane but may also include metasedimentary units. On the southwestern part of profile
5, it likely represents the Kellys Mountain Diorite, but could also include the Price Point
Formation, a small unit onshore from which no physical property data are available.
BS7, associated with a low gravity anomaly, is likely the Ingonish Island Rhyolite with relatively low density of 2500 kg/m3 and high susceptibility of 8.36 x 10-3 SI units 124
(Appendix B). BS8 with density of 3000 kg/m3 and susceptibility of 10.37 x 10-3 SI units is inferred to be the Wreck Cove Dioritic Suite.
Basement source BS4, considered to be a composite unit representing plutonic and metamorphic units of the Bras d’Or terrane, is in contact at the southeastern end of profile 4 with basement source BS6, postulated to represent plutonic units of the Boisdale
Hills pluton ( = 2820 kg/m3; k = 8.21 x 10-3 SI units) based on projections of these rocks into the offshore based on geophysical trends (Figs. 5.4, 5.5).
5.3 Limitations of the Study
The geophysical modeling and resulting geological interpretations made in this study are limited by a number of factors. Additional and better quality deep seismic reflection data might resolve pre-Carboniferous units and the nature and orientation of their contacts, as has been done in Newfoundland as a result of the Lithoprobe East project (e.g., van der Velden et al. 2004). Seismic data with higher resolution images at the Carboniferous and pre-Carboniferous boundary would have allowed for a better constrained basement. The Carboniferous units are mappable to a depth of 3.5 to 4.0 s; deeper units are more difficult to interpret limiting the ability to constrain the shape of the basement bodies particularly in the Cabot Strait area. Although magnetic data are quite detailed, gravity data are sparser, and a more detailed database would allow better resolution in the models. Higher resolution gravity data would have provided better quality data to use with the magnetic interpretations, as in too many places only magnetic data could be used to tie anomalies together as the gravity data were collected at too large a line spacing and hence were gridded too coarsely. In addition, artefacts in the magnetic 125
and especially the gravity maps generated during the study indicate that the various corrections may not have been accurately applied to the data.
The modeling procedure relies on the availability of accurate magnetic susceptibility and density data for rock units in the study area. Such data are very scarce for units in southwestern Newfoundland units. The database for magnetic susceptibility in Cape Breton Island is good, but gravity data are more limited. Furthermore, at the scale of the modeling, only large units could be included, most of which are composite, and the averages obtained from the susceptibility measurements may not be representative of the whole unit. Problems such as those encountered in trying to model the St. Paul Island area demonstrate well the scale problem.
The ultimate test of the models would be deep drilling in offshore areas to determine the nature and thickness of the Carboniferous units and also the character of underlying pre-Carboniferous rock units.
However, even with all of these limitations, the major conclusions of this study concerning the nature of the pre-Carboniferous basement in the Cabot Strait area and correlations of terranes between Cape Breton Island and Newfoundland are likely to be valid.
126
Fig. 5.1a Total magnetic field anomaly map of northeastern Cape Breton Island with geologic map overlay modified from Figure 2.1. Unit abbreviations are as in the caption of Figure 2.1.
127
Fig. 5.1b First vertical derivative magnetic anomaly map of northeastern Cape Breton Island with geologic map overlay modified from Figure 2.1 and abbreviations as in the caption of Figure 2.1.
128
Fig. 5.1c Second vertical derivative magnetic anomaly map of northeastern Cape Breton Island with geologic map overlay modified from Figure 2.1 and abbreviations as in the caption of Figure 2.1.
129
Fig. 5.1d Bouguer (on shore) and free-air (offshore) gravity anomaly map of northeastern Cape Breton Island with geologic map overlay modified from Figure 2.1 and abbreviations as in the caption of Figure 2.1. 130
Fig. 5.1e Map showing horizontal gradient of gravity anomalies with illumination at an azimuth of 315o. Geologic map overlay and unit abbreviations are from Figure 2.1.
131
Fig. 5.2a Total magnetic field anomaly map of southwestern Newfoundland with geologic map overlay modified from Figure 2.2. Unit abbreviations are as in the caption of Figure 2.2.
132
Fig. 5.2b First vertical derivative magnetic anomaly map of southwestern Newfoundland with geologic map overlay modified from Figure 2.2 and abbreviations as in the caption of Figure 2.2.
133
Fig. 5.2c Second vertical derivative magnetic anomaly map of southwestern Newfoundland with geologic map overlay modified from Figure 2.2 and abbreviations as in the caption of Figure 2.2.
134
Fig. 5.2d Bouguer (onshore) and free-air (offshore) gravity anomaly map of southwestern Newfoundland with geologic map overlay modified from Figure 2.2 and abbreviations as in the caption of Figure 2.2. 135
Fig. 5.2e Map showing horizontal gradient of gravity anomalies with illumination at an azimuth of 315o. Geologic map overlay and unit abbreviations are from Figure 2.2.
136
Fig. 5.3a Total magnetic field anomaly map of the study area with geologic map overlay onshore from Figures 2.1 and 2.2. Faults in the offshore are from Langdon and Hall (1994) and this study.
137
Fig. 5.3b First derivative of the total magnetic field anomaly map of the study area with geologic map overlay onshore from Figures 2.1 and 2.2. Faults in the offshore are from Langdon and Hall (1994) and this study.
138
Fig. 5.3c Second derivative of the total magnetic field anomaly map of the study area with geologic map overlay onshore from Figures 2.1 and 2.2. Faults in the offshore are from Langdon and Hall (1994) and this study. 139
Fig.5.3d Bouguer (onshore) and free-air (offshore) gravity anomaly map of the study area with geologic map overlay onshore from Figures 2.1 and 2.2. Faults in the offshore are from Langdon and Hall (1994) and this study.
140
Fig 5.3e Horizontal gradient of gravity anomaly with illumination at an azimuth of 315o. Geologic map overlay onshore from Figures 2.1 and 2.2. Faults in the offshore are from Langdon and Hall (1994) and this study.
141
Fig 5.4 First vertical derivative magnetic map of the study area with geologic map overlay as in Figure 5.3b and inferred terrane correlation between Cape Breton Island and Newfoundland. The Blair River Inlier/Humber Zone are in orange, Aspy terrane and inferred correlative areas in Newfoundland are in yellow, Bras d’Or terrane and inferred correlative areas are in blue, and Mira terrane and inferred correlative areas are in pink. 142
Fig 5.5 First vertical derivative magnetic map of the study area with geologic map overlay as in Figure 5.4 and pre-Carboniferous (GB and BS) units inferred from GM-SYS forward modelled profiles. Dashed circle labeled IMA is the Ingonish magnetic anomaly based on the total field magnetic anomaly map. GRF is George River Fault, the approximate position of the Bras d’Or (Ganderia) – Mira (Avalonia) terrane boundary. IB is inferred offshore extent of the Indian Brook Granodiorite and associated plutons.
143
6.0 CONCLUSIONS
This study investigated the pre-Carboniferous geology of, and geological correlations between, Cape Breton Island and southwestern Newfoundland with the help of geophysical data. Magnetic and gravity data were used together with previously published interpretations of seismic reflection data to refine the results of previous studies and better understand the character of pre-Carboniferous units in the offshore. In addition to enhancing the understanding of geological correlations between northeastern
Cape Breton Island and southwestern Newfoundland, a major focus of the study was to interpret the source of the Ingonish magnetic anomaly.
The main conclusions of the study are:
1. The compiled magnetic (including total field, first derivative, second derivative,
and 400 m-downward continuation) and gravity (Bouguer anomaly onshore, free-
air anomaly offshore, and horizontal gradient) maps display differences consistent
with division of the onshore geology into Bras d’Or terrane, Aspy terrane, and
Blair River Inlier in northeastern Cape Breton Island. In southwestern
Newfoundland, the maps show differences in geophysical characteristics among
the Humber zone northwest of the Cabot Fault and Notre Dame, Port-aux-
Basques, Meelpaeg, Exploits, and Burgeo subzones southeast of the Cabot Fault.
2. Major faults in the area are recognized by linear anomalies and/or by changes in
geophysical characteristics. The Cabot Fault extends across the Cabot Strait west
of St. Paul Island and appears to connect with the Wilkie Brook Fault, the
southern margin of the Blair River Inlier. The Aspy Fault appears to extend
offshore from Cape Breton Island south of St. Paul Island to merge with the Cabot
fault northeast of St. Paul Island. In southwestern Newfoundland, the Red Indian 144
Line/Cape Ray Fault separates Notre Dame subzone from peri-Gondwanan
Ganderian subzones to the southeast. The Cape Ray Fault merges with the Cabot
Fault in the nearshore, so that through most of the Cabot Strait and in Cape Breton
Island, Ganderian rocks of the Aspy terrane are juxtaposed against Grenvillian
basement (Humber zone/Blair River Inlier).
3. The distribution and thickness of the Carboniferous Horton, Windsor, and
Pictou/Morien groups in the Sydney Basin between northeastern Cape Breton
Island and southwestern Newfoundland and the Codroy and Barachois groups in
the St. George’s Bay sub-basin west of Newfoundland varies as a result of
basement topography and structures. Because of the non-uniqueness of
geophysical models, constraints provided by published interpretations of
Lithoprobe/Frontier Geoscience deep seismic reflection profiles and industry
seismic reflection profiles were essential for generating the geophysical models.
4. Two-dimensional models based on total field magnetic and gravity anomaly
profiles and generated with GM-SYS 4.2 modeling software along three NW-SE
lines through the Cabot Strait and one NW-SE line in St. George’s Bay are
consistent the presence of Grenvillian basement northwest of the Cabot Fault in
the Magdalen Basin and St. George Bay sub-basin, thus supporting previously
proposed correlation between the Blair River Inlier and Grenvillian basement
inliers in the Humber zone of western Newfoundland.
5. The three Cabot Strait models show pre-Carboniferous basement southeast of the
Cabot Fault which likely consists of various components of the Aspy terrane near
Cape Breton Island and the Port-aux-Basques, Exploits, and Burgeo subzones
near Newfoundland, indicating that these areas are correlative. A strong linear 145
magnetic anomaly extending from the Port-aux-Basques subzone to the Aspy
terrane may be caused by a mafic orthogneissic unit similar to the Margaree
orthogneiss in Newfoundland but not exposed in the Aspy terrane. Elliptical halo-
like magnetic anomalies in the Cabot Strait are attributed to plutons similar to
those in the Silurian-Devonian Burgeo Batholith in metamorphic basement rock.
The Cape Ray Graben mentioned by Langdon and Hall (1994) has been identified
in the profile models as a basement low.
6. Based on both magnetic and gravity anomalies in the northern part of the Bay of
St. George sub-basin, an ophiolitic body may be present in the subsurface, similar
the one onshore north of the Port au Port Peninsula. Anomalies in the central part
of the sub-basin are caused by components of the Grenvillian basement, perhaps
similar to the Indian head and Steel Mountain inliers.
7. The first derivative and second derivative magnetic maps resolve the Ingonish
magnetic anomaly into four coalescing anomalies. Combined with two 2D
models generated at right angles through the anomaly, the sources of these
anomalies include Late Neoproterozoic Bras d’Or terrane plutons (Wreck Cove
Dioritic Suite, Kelly Mountain Diorite, Indian Brook Granodiorite) and the
overlying Devonian Ingonish Island Rhyolite.
8. The strong magnetic and weak gravity anomalies associated with the Ingonish
magnetic anomaly are a result of burial of the Bras d’Or terrane units beneath 3-6
km of sedimentary rocks and low density and high magnetic characteristics of the
Ingonish Island Rhyolite. 146
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APPENDIX A. Measured density (g/cm3) and susceptibility (x10-3 SI units) in pre-Carboniferous samples from northeastern Cape Breton Island. (arranged by terrane in alphabetical order by unit name)
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit BRAS DOR TERRANE UNITS SB-84-114B 0.10 Gneiss Barachois River Formation AM84-083 0.16 Granodiorite gneiss Barachois River Formation AM84-080 0.28 Granitic gneiss Barachois River Formation AM84-136 0.45 Gneissic granodiorite Barachois River Formation AM84-073B 0.48 Granitic gneiss Barachois River Formation SB-84-114 1.51 Mafic gneiss Barachois River Formation RR87-5507 1.69 Granodiorite Barachois River Formation AM84-070B 4.03 Gneiss Barachois River Formation SB-84-113 4.20 Porphyroblastic gneiss Barachois River Formation AM84-082 4.44 Gneiss Barachois River Formation AM84-079 4.61 Granitic gneiss Barachois River Formation RR87-5505 4.96 Gneiss Barachois River Formation RR87-5508 5.72 Gneiss Barachois River Formation AM84-073A 5.81 Granitic gneiss Barachois River Formation AM84-065B 6.63 Quartzitic gneiss Barachois River Formation SB-84-116 11.47 Metawacke/gneiss Barachois River Formation AM84-064 11.77 Gneiss Barachois River Formation AM84-065A 17.60 Quartzitic gneiss Barachois River Formation SB-84-114 1.51 Mafic gneiss Barachois River Formation AM84-108 0.08 Phyllite Barachois River Formation AM84-109B 0.11 Marble Barachois River Formation AM84-126 0.10 Schist Barachois River Formation AM84-118 0.14 Schist Barachois River Formation AM84-117C 0.21 Schist Barachois River Formation AM84-117B 23.53 Schist Barachois River Formation n = 25 4.46
K1-1064 2.51 0.11 Marble Benacadie Brook Formation K1-1097 2.58 0.19 Marble Benacadie Brook Formation K2-1519 2.67 0.06 Schist Benacadie Brook Formation F15-1561 2.67 0.12 Metasedimentary rock Benacadie Brook Formation F15-1520 2.75 0.03 Metasedimentary rock Benacadie Brook Formation F15-1567A 2.75 1.42 Metasedimentary rock Benacadie Brook Formation F15-1522 2.78 0.24 Hornfels Benacadie Brook Formation K1-1095 2.82 0.00 Marble Benacadie Brook Formation F15-1553B 2.82 0.03 Metasedimentary rock Benacadie Brook Formation K2-1508 2.83 0.25 Metasedimentary rock Benacadie Brook Formation F15-1530 2.85 0.17 Metasedimentary rock Benacadie Brook Formation F15-1521 2.85 0.46 Hornfels Benacadie Brook Formation F15-1567B 2.89 0.40 Metasedimentary rock Benacadie Brook Formation K1-1098 2.93 0.95 Marble Benacadie Brook Formation K1-1312 3.00 0.30 Schist Benacadie Brook Formation n = 15 2.78 0.31
CW86-3701B 0.01 Granite Birch Plain Granite 168
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit AM84-021 0.11 Granodiorite Birch Plain Granite 78-K07A-1626 0.12 Granite Birch Plain Granite AM84-005A 0.16 Granite Birch Plain Granite K9-A030 0.62 Granodiorite Birch Plain Granite AM84-018 0.68 Diorite Birch Plain Granite AM84-156 1.73 Granodiorite Birch Plain Granite K9-A023 2.07 Diorite Birch Plain Granite AM84-017A 2.68 Granite Birch Plain Granite 78-K09B-1522 2.68 Diorite Birch Plain Granite K9-A024 3.99 Granodiorite Birch Plain Granite K9-A029 4.16 Grey diorite Birch Plain Granite K9-A033 4.46 Granodiorite Birch Plain Granite AM84-155A 4.77 Red granite Birch Plain Granite AM84-010 4.87 Granite/granodiorite Birch Plain Granite CW86-3698 5.09 Granite Birch Plain Granite 78-K07A-1625 5.15 Granite Birch Plain Granite K9-A031A 5.29 Granodiorite Birch Plain Granite K09-S43 5.33 Granodiorite Birch Plain Granite K9-A032 5.49 Granodiorite with aplite Birch Plain Granite AM84-067 5.62 Granite Birch Plain Granite 78-K07A-1629 5.78 Diorite Birch Plain Granite SB-84-077 6.50 Granodiorite Birch Plain Granite K9-A026 7.61 Quartz monzonite Birch Plain Granite K9-A019 8.61 Granite Birch Plain Granite AM84-068 8.70 Granite Birch Plain Granite K9-A034A 9.49 Granodiorite Birch Plain Granite AM84-023 10.56 Pink granite Birch Plain Granite SB-84-078 11.71 Granodiorite Birch Plain Granite AM84-011 13.33 Granite/granodiorite Birch Plain Granite AM84-015A 13.70 Biotite granite Birch Plain Granite AM84-014 17.90 Granodiorite Birch Plain Granite K9-A022 18.60 Granite Birch Plain Granite K9-A031B 18.87 Granodiorite Birch Plain Granite AM84-013 20.80 Monzonite Birch Plain Granite AM84-022 20.99 Granodiorite Birch Plain Granite AM84-019 21.00 Hornblende diorite Birch Plain Granite K9-A028 21.00 Granodiorite Birch Plain Granite K9-A027 21.20 Subporphyritic diorite Birch Plain Granite 78-K07A-1628 22.77 Diorite Birch Plain Granite AM84-012 22.77 Granite/granodiorite Birch Plain Granite 78-K09B-1524 24.90 Diorite Birch Plain Granite AM84-020 26.97 Granodiorite Birch Plain Granite CW86-3700 28.87 Granite Birch Plain Granite AM84-016 29.23 Granodiorite Birch Plain Granite 78-K09B-1523 43.77 Diorite Birch Plain Granite K9-A025 46.70 Diorite Birch Plain Granite n = 47 12.07
K1-1406 2.44 6.68 Dioritic rocks Boisdale Hills Pluton MT6-043 2.44 3.64 Quartz diorite Boisdale Hills Pluton K1-1408 2.47 17.29 Granodiorite Boisdale Hills Pluton 169
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit K1-1184 2.48 6.17 Dioritic rocks Boisdale Hills Pluton K1-1015A 2.48 3.26 Microgranite Boisdale Hills Pluton K1-1024 2.51 0.02 Biotite granodiorite Boisdale Hills Pluton K1-1217 2.51 9.19 Diorite Boisdale Hills Pluton K1-1405 2.53 0.08 Biotite granodiorite Boisdale Hills Pluton K1-1324 2.54 0.17 Diorite Boisdale Hills Pluton K1-1262 2.56 4.14 Leucogranite Boisdale Hills Pluton K1-1252 2.57 4.52 Leucogranite Boisdale Hills Pluton K1-1084 2.59 4.16 Biotite granodiorite Boisdale Hills Pluton K1-1325 2.60 0.07 Diorite Boisdale Hills Pluton F15-1544 2.60 0.08 Biotite hornblende granodioriteBoisdale Hills Pluton F15-1599 2.60 8.18 Biotite granodiorite Boisdale Hills Pluton K1-1343 2.61 9.99 Diorite Boisdale Hills Pluton CCB90-67A 2.62 0.06 Granite Boisdale Hills Pluton K1-1154 2.62 9.26 Diorite Boisdale Hills Pluton K1-1228 2.62 8.41 Biotite granodiorite Boisdale Hills Pluton K1-1264 2.62 0.31 Leucogranite Boisdale Hills Pluton K1-1255 2.63 0.42 Diorite Boisdale Hills Pluton K1-1298 2.63 0.09 Biotite granodiorite Boisdale Hills Pluton K1-1354 2.63 0.12 Granodiorite Boisdale Hills Pluton BHC92-208 2.64 0.07 Granite Boisdale Hills Pluton K1-1290 2.64 0.18 Biotite granodiorite Boisdale Hills Pluton K1-1231 2.64 5.73 Granodiorite Boisdale Hills Pluton BHC91-111 2.66 0.16 Diorite Boisdale Hills Pluton F15-1597 2.67 0.10 Granodiorite Boisdale Hills Pluton F15-1598 2.67 0.45 Diorite Boisdale Hills Pluton K1-1421 2.67 11.00 Granodiorite Boisdale Hills Pluton K1-1412 2.67 8.37 Biotite granodiorite Boisdale Hills Pluton K1-1242 2.68 19.06 Granodiorite Boisdale Hills Pluton K1-1278 2.68 7.04 Granodiorite Boisdale Hills Pluton F15-1526 2.69 11.36 Hornblende granodiorite Boisdale Hills Pluton K1-1008 2.69 25.90 Granodiorite Boisdale Hills Pluton K1-1197 2.70 2.39 Biotite granodiorite Boisdale Hills Pluton K1-1292 2.71 0.20 Biotite granodiorite Boisdale Hills Pluton F15-1524 2.71 0.91 Biotite granodiorite Boisdale Hills Pluton K1-1087 2.71 1.19 Diorite Boisdale Hills Pluton K1-1088 2.73 0.23 Diorite Boisdale Hills Pluton K1-1192 2.73 4.77 Microgranite Boisdale Hills Pluton F15-1525B 2.74 21.93 Biotite granodiorite Boisdale Hills Pluton K1-1164 2.74 9.55 Biotite granodiorite Boisdale Hills Pluton K1-1179 2.74 5.35 Biotite granodiorite Boisdale Hills Pluton K1-1236 2.75 17.96 Granodiorite Boisdale Hills Pluton F15-1591 2.75 11.31 Granodiorite Boisdale Hills Pluton K1-1148 2.75 5.17 Biotite granodiorite Boisdale Hills Pluton F15-1602 2.76 1.56 Granodiorite Boisdale Hills Pluton F15-1542 2.76 3.30 Granodiorite Boisdale Hills Pluton K1-1294 2.77 6.05 Biotite granodiorite Boisdale Hills Pluton K1-1180 2.78 6.96 Biotite granodiorite Boisdale Hills Pluton F15-1525A 2.78 7.23 Biotite granodiorite Boisdale Hills Pluton K1-1254 2.79 0.19 Diorite Boisdale Hills Pluton K1-1086 2.79 0.64 Diorite Boisdale Hills Pluton 170
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit K1-1331 2.80 0.29 Microdiorite Boisdale Hills Pluton K2-1581 2.80 1.42 Granodiorite Boisdale Hills Pluton K1-1233 2.80 12.29 Granodiorite Boisdale Hills Pluton K1-1446 2.82 9.95 Leucotonalite Boisdale Hills Pluton BHC91-138 2.83 20.22 Granodiorite Boisdale Hills Pluton K1-1369 2.83 0.17 Diorite Boisdale Hills Pluton K1-1273 2.83 3.82 Biotite granodiorite Boisdale Hills Pluton K1-1390 2.83 38.03 Diorite Boisdale Hills Pluton K1-1340 2.84 5.67 Granodiorite Boisdale Hills Pluton K1-1016 2.84 72.75 Diorite Boisdale Hills Pluton K1-1432 2.85 0.16 Granodiorite Boisdale Hills Pluton K1-1199 2.85 15.54 Granodiorite Boisdale Hills Pluton K1-1085 2.86 13.90 Biotite granodiorite Boisdale Hills Pluton K1-1461 2.87 19.90 Granodiorite Boisdale Hills Pluton F15-1543 2.87 8.44 Granodiorite Boisdale Hills Pluton K1-1260 2.88 20.95 Diorite Boisdale Hills Pluton K1-1012 2.88 33.15 Biotite granodiorite Boisdale Hills Pluton K1-1020 2.89 0.04 Biotite granodiorite Boisdale Hills Pluton K1-1068 2.89 55.38 Diorite Boisdale Hills Pluton K1-1335 2.90 0.31 Diorite Boisdale Hills Pluton K1-1143 2.90 9.10 Granodiorite Boisdale Hills Pluton K1-1009 2.91 17.04 Microgranite Boisdale Hills Pluton K1-1023 2.93 0.38 Biotite granodiorite Boisdale Hills Pluton K1-1396 2.94 3.87 Diorite Boisdale Hills Pluton K1-1347 2.95 36.70 Granodiorite Boisdale Hills Pluton K1-1237 2.95 61.23 Granodiorite Boisdale Hills Pluton K1-1032 2.95 12.89 Diorite Boisdale Hills Pluton K1-1089 2.96 0.27 Diorite Boisdale Hills Pluton K1-1452 2.96 0.32 Diorite Boisdale Hills Pluton K1-1418 2.96 3.79 Biotite granodiorite Boisdale Hills Pluton K1-1373 2.96 15.64 Diorite Boisdale Hills Pluton K1-1425 2.97 0.17 Granodiorite Boisdale Hills Pluton K1-1356 3.00 0.04 Biotite granodiorite Boisdale Hills Pluton K1-1013 3.00 0.25 Biotite granodiorite Boisdale Hills Pluton K1-1365 3.00 0.40 Diorite Boisdale Hills Pluton K1-1147 3.00 1.24 Granodiorite Boisdale Hills Pluton K1-1146 3.00 13.07 Granodiorite Boisdale Hills Pluton K1-1377 3.02 18.49 Diorite Boisdale Hills Pluton K1-1375 3.03 1.25 Diorite Boisdale Hills Pluton K1-1239 3.04 0.18 Granodiorite Boisdale Hills Pluton K1-1454 3.04 4.69 Microgranite Boisdale Hills Pluton K1-1449 3.04 6.13 Microgranite Boisdale Hills Pluton K1-1082 3.05 0.41 Diorite Boisdale Hills Pluton K1-1339 3.06 0.81 Granodiorite Boisdale Hills Pluton K1-1357 3.08 0.07 Biotite granodiorite Boisdale Hills Pluton K1-1420 3.08 6.06 Granodiorite Boisdale Hills Pluton K1-1374 3.09 6.67 Diorite Boisdale Hills Pluton K1-1318 3.09 5.72 Diorite Boisdale Hills Pluton K1-1394 3.09 10.11 Biotite granodiorite Boisdale Hills Pluton K1-1386 3.09 36.23 Diorite Boisdale Hills Pluton F15-1551 3.10 0.19 Hornblende granodiorite Boisdale Hills Pluton 171
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit K1-1285 3.12 0.24 Granodiorite Boisdale Hills Pluton K1-1269 3.13 1.25 Diorite Boisdale Hills Pluton K1-1212 3.14 0.12 Granodiorite Boisdale Hills Pluton K1-1404 3.15 0.29 Biotite granodiorite Boisdale Hills Pluton K1-1440 3.18 1.37 Diorite Boisdale Hills Pluton K1-1296 3.19 12.71 Biotite granodiorite Boisdale Hills Pluton K1-1350 3.21 21.15 Granodiorite Boisdale Hills Pluton K1-1277 3.21 0.31 Granodiorite Boisdale Hills Pluton BHC91-137 3.24 0.27 Diorite Boisdale Hills Pluton n = 114 2.82 8.21
F15-1535 2.42 0.19 Metasedimentary rock Bourinot Group (Undivided) K1-1117 2.49 0.23 Volcanic Bourinot Group (Undivided) MT6-024 2.50 0.08 Lapilli tuff Bourinot Group (Undivided) CCB90-65D 2.50 0.12 Tuff Bourinot Group (Dugald Formation) K1-1121 2.52 0.04 Limestone breccia Bourinot Group (Undivided) BHC91-118B 2.53 0.59 Tuff-conglomerate Bourinot Group (Gregwa Formation) BHC91-113C 2.54 0.82 Mafic lithic tuff Bourinot Group (Gregwa Formation) BHC91-134 2.56 0.31 Rhyolite Bourinot Group (Eskasoni Formation) BHC91-107A 2.57 0.37 Rhyolite Bourinot Group (Eskasoni Formation) F15-1533 2.58 0.27 Siltstone ? Bourinot Group (Undivided) BHC91-121 2.58 0.76 Lithic tuff Bourinot Group (Gregwa Formation) CCB90-65C 2.60 0.27 Crystal lithic tuff Bourinot Group (Dugald Formation) K2-1582 2.61 0.19 Metasedimentary rock Bourinot Group (Undivided) BHC91-133 2.61 0.25 Lithic tuff Bourinot Group (Gregwa Formation) F15-1532 2.62 0.01 Metasedimentary rock Bourinot Group (Undivided) BHC91-110 2.64 0.11 Silstone Bourinot Group (Eskasoni Formation) BHC91-102 2.66 0.42 Siltstone Bourinot Group (Dugald Formation) K1-1592 2.67 0.14 Metasedimentary rock Bourinot Group (Undivided) CCB90-65B 2.67 0.69 Siltstone Bourinot Group (Dugald Formation) BHC91-101 2.67 1.11 Lithic tuff Bourinot Group (Gregwa Formation) CCB90-66C 2.67 37.20 Basalt Bourinot Group (Eskasoni Formation) BHC91-108A 2.68 0.05 Quartzite conglomerate Bourinot Group (Eskasoni Formation) BHC91-113A 2.68 1.11 Lithic tuff Bourinot Group (Gregwa Formation) BHC91-113B 2.68 12.12 Tuff sandstone Bourinot Group (Gregwa Formation) BHC92-204 2.69 21.40 Basalt Bourinot Group (Eskasoni Formation) BHC91-119B 2.71 0.02 Quartzite Bourinot Group (Dugald Formation) BHC91-120 2.71 0.36 Rhyolite Bourinot Group (Eskasoni Formation) BHC91-127B 2.72 0.73 Breccia / tuff Bourinot Group (Eskasoni Formation) BHC91-127A 2.72 0.42 Rhyolite Bourinot Group (Eskasoni Formation) BHC91-142B 2.73 1.67 Lithic tuff Bourinot Group (Gregwa Formation) BHC91-108B 2.73 0.31 Basalt Bourinot Group (Eskasoni Formation) BHC91-139B 2.74 2.97 Basalt Bourinot Group (Eskasoni Formation) F15-1562 2.75 0.16 Metasedimentary rock Bourinot Group (Undivided) BHC91-118A 2.76 0.61 Maroon sandstone Bourinot Group (Gregwa Formation) BHC91-117 2.76 0.61 Mafic tuf Bourinot Group (Gregwa Formation) F15-1531 2.76 0.28 Metasedimentary rock Bourinot Group (Undivided) BHC91-107B 2.78 0.77 Dacite Bourinot Group (Eskasoni Formation) BHC91-135 2.81 44.00 Basalt Bourinot Group (Eskasoni Formation) BHC91-140 2.81 6.28 Basalt Bourinot Group (Eskasoni Formation) BHC91-126 2.82 1.87 Rhyolite Bourinot Group (Eskasoni Formation) 172
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit BHC91-124 2.82 39.60 Massive basalt Bourinot Group (Eskasoni Formation) BHC91-139A 2.84 13.91 Basalt Bourinot Group (Eskasoni Formation) BHC91-143 2.88 40.13 Siltstone Bourinot Group (Eskasoni Formation) BHC91-119A 2.90 11.49 Basalt Bourinot Group (Eskasoni Formation) BHC91-125 2.91 0.51 Rhyolite Bourinot Group (Eskasoni Formation) BHC91-103 2.91 12.93 Siltstone Bourinot Group (Eskasoni Formation) BHC91-141 2.93 4.85 Basalt Bourinot Group (Eskasoni Formation) CCB90-66A 2.97 0.23 Tuffaceous siltstone Bourinot Group (Eskasoni Formation) CCB90-66B 3.00 0.02 Quartzite Bourinot Group (Eskasoni Formation) BH90-8 3.00 0.39 Andesite Bourinot Group (Eskasoni Formation) CCB90-65A 3.00 0.82 Siltstone Bourinot Group (Dugald Formation) BHC91-109 3.04 0.41 Rhyolite Bourinot Group (Eskasoni Formation) CCB90-70B 3.07 0.49 Basalt Bourinot Group (Eskasoni Formation) BHC91-123 3.12 19.67 Massive siltstone Bourinot Group (Eskasoni Formation) BHC91-112A 3.13 0.85 Rhyolite Bourinot Group (Eskasoni Formation) F15-1534 3.17 0.29 Metasedimentary rock Bourinot Group (Undivided) n = 56 2.75 5.12
78-K09B-1569 0.04 Granite Cape Smokey Granite 78-K09B-1504 0.08 Granite Cape Smokey Granite 78-K09B-1549 0.10 Granite Cape Smokey Granite 78-K09B-1508 0.11 Diorite Cape Smokey Granite 78-K09B-1564 0.11 Granite Cape Smokey Granite 78-K09B-1572 0.13 Granite Cape Smokey Granite 78-K09B-1558 0.14 Granite Cape Smokey Granite 78-K09B-1552 0.14 Granite Cape Smokey Granite 78-K09B-1512 0.15 Granite Cape Smokey Granite 78-K09B-1541 0.16 Granite Cape Smokey Granite 78-K09B-1769 0.16 Granite Cape Smokey Granite 78-K09B-1565 0.17 Granite Cape Smokey Granite 78-K09B-1573 0.18 Granite Cape Smokey Granite 78-K09B-1509 0.18 Diorite Cape Smokey Granite 78-K09B-1571 0.19 Granite Cape Smokey Granite 78-K09B-1563 0.21 Granite Cape Smokey Granite 78-K09B-1766 0.27 Granite Cape Smokey Granite 78-K09B-1577 0.33 Granite Cape Smokey Granite 78-K09B-1761 0.37 Granite Cape Smokey Granite 78-K09B-1768 0.49 Granite Cape Smokey Granite 78-K09B-1568 0.49 Granite Cape Smokey Granite 78-K09B-1576 0.51 Granite Cape Smokey Granite 78-K09B-1751 0.66 Granite Cape Smokey Granite 78-K09B-1760 0.66 Granite Cape Smokey Granite 78-K09B-1767 0.70 Granite Cape Smokey Granite 78-K09B-1759 0.88 Granite Cape Smokey Granite 78-K09B-1753 1.00 Granite Cape Smokey Granite 78-K09B-1765 1.17 Granite Cape Smokey Granite 78-K09B-1581 1.28 Granite Cape Smokey Granite 78-K09B-1510 1.32 Granite Cape Smokey Granite 78-K09B-1567 1.38 Granite Cape Smokey Granite 78-K09B-1586 1.90 Granite Cape Smokey Granite 78-K09B-1507 1.96 Diorite Cape Smokey Granite 173
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit 78-K09B-1557 2.19 Granite Cape Smokey Granite 78-K09B-1506 2.27 Diorite Cape Smokey Granite 78-K09B-1559 2.41 Granite Cape Smokey Granite 78-K09B-1561 2.53 Granite Cape Smokey Granite 78-K09B-1566 2.88 Granite Cape Smokey Granite 78-K09B-1583 2.97 Granite Cape Smokey Granite 78-K09B-1585 2.99 Granite Cape Smokey Granite 78-K09B-1763 3.01 Granite Cape Smokey Granite 78-K09B-1545 3.47 Granite Cape Smokey Granite 78-K09B-1764 3.70 Granite Cape Smokey Granite K09-S115 3.78 Diorite Cape Smokey Granite 78-K09B-1551 4.16 Granite Cape Smokey Granite 78-K09B-1584 4.18 Granite Cape Smokey Granite 78-K09B-1560 4.28 Granite Cape Smokey Granite 78-K09B-1511 4.57 Granite Cape Smokey Granites 78-K09B-1543 4.95 Granite Cape Smokey Granite 78-K09B-1582 5.43 Granite Cape Smokey Granite 78-K09B-1542 7.65 Granite Cape Smokey Granite 78-K09B-1555 8.08 Granite Cape Smokey Granite 78-K09B-1503 8.77 Granite Cape Smokey Granite 78-K09B-1505 11.09 Granite Cape Smokey Granite 78-K09B-1752 14.03 Granite Cape Smokey Granite 78-K09B-1762 21.00 Granite Cape Smokey Granite 78-K09B-1544 31.83 Granite Cape Smokey Granite n = 57 3.16
SB-84-025 0.02 Foliated diorite Cross Mtn Granite SB-84-024 0.06 Granite Cross Mtn Granite AM84-047A 0.07 Biotite granite Cross Mtn Granite SB-84-027 0.12 Granodiorite Cross Mtn Granite AM84-044 0.12 Muscovite granite Cross Mtn Granite AM84-048 0.14 Biotite granodiorite Cross Mtn Granite RR84-026 0.26 Granite Cross Mtn Granite AM84-045 0.44 Tonalite Cross Mtn Granite AM84-046 0.55 Biotite granodiorite Cross Mtn Granite AM84-050 0.60 Granite Cross Mtn Granite SB-84-026 2.17 Granodiorite Cross Mtn Granite AM84-047B 12.13 Biotite granite Cross Mtn Granite n = 12 1.39
RR-88-6071 2.400 0.55 Migmatite Frenchvale Road Mmm Suite RR-88-6033 2.440 0.36 Marble Frenchvale Road Mmm Suite RR-88-6070 2.500 0.40 Gneiss Frenchvale Road Mmm Suite RR-88-6028 2.600 0.02 Marble Frenchvale Road Mmm Suite RR-88-6029 2.619 0.01 Quartzite Frenchvale Road Mmm Suite RR-88-6026D2.644 0.02 Marble Frenchvale Road Mmm Suite RR-88-6026A2.659 0.13 Andalusite gneiss Frenchvale Road Mmm Suite RR-88-6016 2.667 0.16 Quartzite Frenchvale Road Mmm Suite RR-88-6073 2.667 0.23 Gneiss Frenchvale Road Mmm Suite RR-88-6069 2.667 0.26 Gneiss Frenchvale Road Mmm Suite RR-88-6031 2.680 0.48 Marble Frenchvale Road Mmm Suite 174
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit RR-88-6068 2.706 0.03 Marble Frenchvale Road Mmm Suite RR-88-6032 2.707 0.69 Marble Frenchvale Road Mmm Suite RR-88-6067 2.714 0.33 Gneiss Frenchvale Road Mmm Suite RR-88-6019 2.714 0.39 Gneiss Frenchvale Road Mmm Suite RR-88-6026C2.727 0.29 Andalusite gneiss Frenchvale Road Mmm Suite RR-88-6030 2.732 2.61 Mafic rock Frenchvale Road Mmm Suite RR-88-6026B2.750 0.40 Andalusite gneiss Frenchvale Road Mmm Suite RR-88-6035 2.771 0.20 Blk quartzite Frenchvale Road Mmm Suite RR-88-6017 2.800 0.47 Gneiss Frenchvale Road Mmm Suite RR-88-6072 2.813 0.38 Gneiss Frenchvale Road Mmm Suite RR-88-6034 2.836 0.42 Marble Frenchvale Road Mmm Suite RR-88-6027 2.846 0.02 Calc-silicate Frenchvale Road Mmm Suite RR-88-6015 2.886 10.38 Basalt Frenchvale Road Mmm Suite RR-88-6036 3.000 0.08 Semipelite Frenchvale Road Mmm Suite n = 25 2.702 0.77
K10-S21 0.06 Cg diorite Gisborne Flowage Quartz Diorite n =1 0.06
CW86-3705 0.07 Diorite Indian Brook Granodiorite 78-K07B-1520 0.11 Granite Indian Brook Granodiorite AM84-034 0.19 Granite-granodiorite Indian Brook Granodiorite AM84-084C 0.23 Biotite granite Indian Brook Granodiorite AM84-172 0.37 Dioritic gneiss Indian Brook Granodiorite 78-K07B-1521 0.75 Granite Indian Brook Granodiorite 78-K07B-1549 0.76 Granite Indian Brook Granodiorite AM84-027 1.21 Granite Indian Brook Granodiorite CW86-3703 2.17 Diorite Indian Brook Granodiorite 78-K07B-1771 2.24 Granite Indian Brook Granodiorite AM84-173 2.26 Granodiorite Indian Brook Granodiorite 78-K07B-1644 2.86 Granite Indian Brook Granodiorite AM84-158 3.33 Granodiorite Indian Brook Granodiorite SB95-034A 3.38 Diorite Indian Brook Granodiorite SB95-034B 3.66 Mafic diorite Indian Brook Granodiorite AM84-149 3.74 Granodiorite/basalt Indian Brook Granodiorite AM84-009A 4.03 Granodiorite Indian Brook Granodiorite AM84-036B 4.79 Granodiorite Indian Brook Granodiorite SB-84-075 5.55 Dark monzodior-no obvious qtzIndian Brook Granodiorite AM84-025 6.45 Biotite granite Indian Brook Granodiorite AM84-007 7.07 Granodiorite Indian Brook Granodiorite RR87-5513 7.21 Biotite granodiorite Indian Brook Granodiorite AM84-085A 7.41 Granite Indian Brook Granodiorite RR84-126 7.95 Granitoid gneiss Indian Brook Granodiorite SB95-035 8.31 Diorite Indian Brook Granodiorite AM84-089A 8.36 Quartz monzodiorite Indian Brook Granodiorite 78-K07B-1561 8.52 Monzonite Indian Brook Granodiorite CW86-3704 8.89 Diorite Indian Brook Granodiorite 78-K07B-1548 9.08 Granite Indian Brook Granodiorite RR84-121 9.26 Granodiorite Indian Brook Granodiorite RR84-120 9.56 Granodiorite Indian Brook Granodiorite RR87-5502 9.86 Gneissic granitoid Indian Brook Granodiorite 175
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit AM84-006 10.00 Granodiorite Indian Brook Granodiorite SB-84-080 10.33 Dioritic hybrid Indian Brook Granodiorite AM84-076 10.55 Granodiorite Indian Brook Granodiorite 78-K07B-1645 10.61 Granite Indian Brook Granodiorite AM84-024 10.62 Granite Indian Brook Granodiorite AM84-148 10.69 Granodiorite Indian Brook Granodiorite SB95-033 10.75 Granodiorite Indian Brook Granodiorite AM84-008 11.67 Granodiorite Indian Brook Granodiorite 78-K07B-1643 11.90 Granite Indian Brook Granodiorite AM84-151 12.27 Granite Indian Brook Granodiorite AM84-028 13.30 Biotite granite Indian Brook Granodiorite SB-84-079 13.30 Granodiorite Indian Brook Granodiorite RR87-5501 13.87 Gneiss Indian Brook Granodiorite SB-84-13 13.95 Granodiorite Indian Brook Granodiorite CW86-3706 14.10 Tonalite? Indian Brook Granodiorite 78-K07B-1765 14.60 Granodiorite Indian Brook Granodiorite AM84-030 14.67 Granite/granodiorite Indian Brook Granodiorite 78-K07B-1566 16.07 Granodiorite Indian Brook Granodiorite AM84-152A 16.30 Microdiorite Indian Brook Granodiorite AM84-152B 16.40 Diorite Indian Brook Granodiorite AM84-069 16.47 Granodiorite Indian Brook Granodiorite 78-K07B-1525 16.53 Monzonite Indian Brook Granodiorite 78-K07B-1550 17.03 Granite Indian Brook Granodiorite SB95-036 17.40 Diorite Indian Brook Granodiorite RR87-5504 17.40 Granodiorite Indian Brook Granodiorite AM84-035 17.57 Granodiorite Indian Brook Granodiorite AM84-075 18.23 Granodiorite Indian Brook Granodiorite AM84-026 18.40 Diorite/diabase Indian Brook Granodiorite AM84-153 20.17 Granodiorite Indian Brook Granodiorite AM84-091 20.80 Monzodiorite Indian Brook Granodiorite AM84-066 20.93 Granodiorite Indian Brook Granodiorite RR84-127 20.97 Granodiorite? Indian Brook Granodiorite AM84-036A 21.85 Granodiorite Indian Brook Granodiorite SB-84-015 21.90 Granodiorite Indian Brook Granodiorite RR87-5503 21.97 Granodiorite Indian Brook Granodiorite RR84-129 22.09 Granodiorite Indian Brook Granodiorite AM84-029 22.30 Granodiorite Indian Brook Granodiorite 78-K07B-1519 22.30 Granite Indian Brook Granodiorite 78-K07B-1526 22.83 Monzonite Indian Brook Granodiorite SB-84-016 23.37 Granodiorite Indian Brook Granodiorite AM84-150 24.63 Granodiorite Indian Brook Granodiorite AM84-085B 24.70 Granodiorite Indian Brook Granodiorite AM84-154 25.13 Granodiorite Indian Brook Granodiorite 78-K07B-1517 25.27 Quartz monzonite Indian Brook Granodiorite RR84-128B 25.83 Granodiorite Indian Brook Granodiorite AM84-032 25.87 Granodiorite Indian Brook Granodiorite AM84-088 26.00 Granodiorite Indian Brook Granodiorite AM84-033 26.33 Granite-granodiorite Indian Brook Granodiorite AM84-031 26.63 Granodiorite Indian Brook Granodiorite 78-K07B-1642 27.27 Granite Indian Brook Granodiorite AM84-157 27.50 Granodiorite Indian Brook Granodiorite 176
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit RR84-128A 27.83 Granodiorite and xenolith Indian Brook Granodiorite AM84-086 29.03 Granodiorite Indian Brook Granodiorite AM84-160A 30.83 Biotite hbl granodiorite Indian Brook Granodiorite 78-K07B-1528 31.57 Granodiorite Indian Brook Granodiorite SB-84-014 32.77 Granodiorite Indian Brook Granodiorite AM84-002 36.20 Tonalite Indian Brook Granodiorite 78-K07B-1768 38.57 Granodiorite Indian Brook Granodiorite AM84-160B 46.27 Biotite hbl granite Indian Brook Granodiorite n = 91 14.99
CW87-5008 0.02 Granodiorite Ingonish River Tonalite RR84-025 0.03 Granite Ingonish River Tonalite RR84-016 0.05 Granite Ingonish River Tonalite RR84-015 0.09 Tonalite Ingonish River Tonalite K09-S84 0.09 Altered granite Ingonish River Tonalite RR84-013 0.17 Granite Ingonish River Tonalite K09-S97 0.20 Felsic bands in diorite Ingonish River Tonalite RR84-024 0.34 Pink granodiorite Ingonish River Tonalite AM84-063 0.38 Diorite Ingonish River Tonalite K10-S27 0.43 Cg pink/red granite Ingonish River Tonalite RR84-023 0.64 White granodiorite Ingonish River Tonalite K09-S42 0.88 Diorite Ingonish River Tonalite K09-S41 0.88 Diorite Ingonish River Tonalite K10-S15 1.08 Hornblende gabbro Ingonish River Tonalite K09-S98 1.22 Dioritic rock Ingonish River Tonalite SB86-3182 3.13 Tonalite Ingonish River Tonalite K09-S35 3.61 Granodiorite Ingonish River Tonalite K09-S85 4.02 Diorite/amphibolite Ingonish River Tonalite CW87-5002 4.18 Tonalite Ingonish River Tonalite RR87-5511 4.34 Gneiss/granodiorite Ingonish River Tonalite AM84-061 5.64 Monzodiorite Ingonish River Tonalite K09-S36 6.12 Granodiorite Ingonish River Tonalite K09-S38 6.84 Granite Ingonish River Tonalite K09-S39 7.35 Granodiorite Ingonish River Tonalite SB86-3184 7.86 Tonalite Ingonish River Tonalite K09-S37 10.00 Diorite Ingonish River Tonalite K10-S19 10.73 Tonalite Ingonish River Tonalite K09-S109 11.40 Granite Ingonish River Tonalite RR87-5512 37.10 Microdiorite Ingonish River Tonalite RR84-124 55.50 Diorite Ingonish River Tonalite n = 30 6.14
RR84-058 0.04 Diorite Kathy Road Dioritic Suite SB87-5816 0.06 Diorite Kathy Road Dioritic Suite SB-84-029 0.12 Diorite Kathy Road Dioritic Suite SB-84-134 0.17 Micaceous diorite Kathy Road Dioritic Suite CF88-157 0.23 Diorite Kathy Road Dioritic Suite RR87-5618B 0.24 Clotted diorite Kathy Road Dioritic Suite RR84-42 0.24 Granite gneiss Kathy Road Dioritic Suite SB-84-043 0.30 Foliated diorite Kathy Road Dioritic Suite RR84-44 0.38 Diorite Kathy Road Dioritic Suite 177
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit SB-84-095 0.59 Foliated diorite Kathy Road Dioritic Suite CF88-100 0.76 Diorite Kathy Road Dioritic Suite SB-84-041 0.86 Diorite Kathy Road Dioritic Suite SB-84-047 0.96 Diorite Kathy Road Dioritic Suite RR84-030 1.06 Diorite Kathy Road Dioritic Suite CF88-135 1.10 Diorite Kathy Road Dioritic Suite CF88-521 1.26 Leucotonalite Kathy Road Dioritic Suite CF88-101 1.37 Diorite Kathy Road Dioritic Suite SB-84-039 1.41 Speckled mg diorite Kathy Road Dioritic Suite CF88-516 1.86 Leucotonalite-tonalite Kathy Road Dioritic Suite CF88-119 2.60 Diorite Kathy Road Dioritic Suite CF88-156 2.72 Diorite Kathy Road Dioritic Suite SB-84-096 2.98 Diorite Kathy Road Dioritic Suite CF88-159 5.05 Diorite Kathy Road Dioritic Suite RR84-100A 5.39 Diorite Kathy Road Dioritic Suite RR84-43 6.19 Melanocratic diorite Kathy Road Dioritic Suite SB-84-046 6.48 Diorite/amphibolite Kathy Road Dioritic Suite CF88-130 8.65 Diorite Kathy Road Dioritic Suite SB-84-124 19.07 Diorite Kathy Road Dioritic Suite CF88-160 25.30 Diorite Kathy Road Dioritic Suite n = 29 3.36
SB78-1047 0.08 Pink granite in gneiss Kellys Mountain Gneiss SB78-1183 0.34 Granite/gneiss Kellys Mountain Gneiss SB78-1045 0.47 Felsic dyke in gneiss Kellys Mountain Gneiss SB78-1018 1.68 Biotite gneiss Kellys Mountain Gneiss SB78-1244 3.16 Mafic gneiss Kellys Mountain Gneiss SB78-1049 6.32 Diorite dyke Kellys Mountain Gneiss SB78-1181 12.27 Banded gneiss Kellys Mountain Gneiss n = 7 3.47
SB78-1010 0.06 Pink granite/alaskite Kellys Mountain Granite SB78-1068 0.06 Alaskite, granite contact Kellys Mountain Granite SB78-1144 0.06 Granite Kellys Mountain Granite SB78-1118 0.07 Mg red granite Kellys Mountain Granite SB78-1158 0.08 Granite Kellys Mountain Granite SB78-1140 0.08 Red granite, bio bearing Kellys Mountain Granite SB78-1080 0.09 Granite Kellys Mountain Granite SB78-1185 0.09 Red granite Kellys Mountain Granite SB78-1247 0.11 Red granite Kellys Mountain Granite SB78-1143 0.11 Granite Kellys Mountain Granite SB78-1186 0.11 More mafic granite Kellys Mountain Granite SB78-1223 0.12 Red granite Kellys Mountain Granite SB78-1149 0.12 Pink granite Kellys Mountain Granite SB78-1224 0.13 Granite Kellys Mountain Granite SB78-1191 0.14 Granite Kellys Mountain Granite SB78-1227 0.14 Red granite Kellys Mountain Granite SB78-1079 0.19 Red granite porphyry Kellys Mountain Granite SB78-1117 0.20 Cg granite Kellys Mountain Granite SB78-1146 0.23 Fg & cg granite contact Kellys Mountain Granite SB78-1212 0.28 Granite and diorite Kellys Mountain Granite 178
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit SB78-1034 0.31 Diorite Kellys Mountain Granite SB78-1027 0.35 Granite Kellys Mountain Granite SB78-1218 0.36 Granite Kellys Mountain Granite SB78-1111 0.37 Granite Kellys Mountain Granite SB78-1139 0.43 Pink granite, with biotite Kellys Mountain Granite SB78-1153 0.53 Granite Kellys Mountain Granite SB78-1071 0.61 Granite Kellys Mountain Granite SB78-1033 0.66 Aplite Kellys Mountain Granite SB78-1009 0.79 Pink granite (alaskite) Kellys Mountain Granite SB78-1194 1.01 Red granite Kellys Mountain Granite SB78-1173 1.08 Fg porphyritic granite Kellys Mountain Granite SB78-1157 1.61 Red granite Kellys Mountain Granite SB78-1147 1.73 Granite Kellys Mountain Granite SB78-1171 1.77 Fg qtz-rich granite Kellys Mountain Granite SB78-1120 1.82 Granite Kellys Mountain Granite SB78-1152 1.89 Red granite Kellys Mountain Granite SB78-1150 1.89 Mg red granite Kellys Mountain Granite SB78-1069 1.90 Alaskite Kellys Mountain Granite SB78-1167 1.92 Mg-cg red granite Kellys Mountain Granite SB78-1089 1.96 Biotite quartz monzonite Kellys Mountain Granite SB78-1207 2.00 Red granite Kellys Mountain Granite SB78-1148 2.18 Granite Kellys Mountain Granite SB78-1145 2.33 Granite Kellys Mountain Granite SB78-1028 2.38 Diorite Kellys Mountain Granite SB78-1015 2.77 Mg quartz monzonite Kellys Mountain Granite SB78-1008 2.90 Diorite Kellys Mountain Granite SB78-1245 3.50 Red granite Kellys Mountain Granite SB78-1178 3.64 Pink granite Kellys Mountain Granite SB78-1161 4.19 Granite Kellys Mountain Granite SB78-1246 4.20 Red granite, biotite rich Kellys Mountain Granite SB78-1163 4.25 Red granite Kellys Mountain Granite SB78-1160 4.42 Red granite Kellys Mountain Granite SB78-1088 4.74 Biotite quartz monzonite Kellys Mountain Granite SB78-1077 4.94 Red granite porphyry Kellys Mountain Granite SB78-1210 5.17 Granite Kellys Mountain Granite SB78-1007 5.47 Diorite with pyrite Kellys Mountain Granite SB78-1142 6.08 Pink granite Kellys Mountain Granite SB78-1200 6.12 Granite and diorite Kellys Mountain Granite SB78-1123 6.14 Granite, diorite Kellys Mountain Granite SB78-1085 6.18 Granite Kellys Mountain Granite SB78-1075 6.39 Diorite and granite Kellys Mountain Granite SB78-1162 6.44 Biotite-rich pink granite Kellys Mountain Granite SB78-1086 6.52 Pink monzonite Kellys Mountain Granite SB78-1012 6.59 Xeno in monzonite Kellys Mountain Granite SB78-1011 7.07 Mafic bands in monzonite Kellys Mountain Granite SB78-1074 8.56 Diorite, pegmatoid patches Kellys Mountain Granite SB78-1031 9.83 Quartz monzonite Kellys Mountain Granite SB78-1208 10.47 Monzonite Kellys Mountain Granite SB78-1204 10.64 Biotite granite Kellys Mountain Granite SB78-1038 10.71 Hbl qtz monzonite Kellys Mountain Granite SB78-1073 12.63 Dolomite and red granite Kellys Mountain Granite 179
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit SB78-1014 36.77 Monzonite Kellys Mountain Granite n = 72 3.36
SB78-1114B 0.12 Diorite Kellys Mountain Dioritic Rocks SB78-1232 0.17 Granite Kellys Mountain Dioritic Rocks SB78-1000 0.23 Melanodiorite Kellys Mountain Dioritic Rocks SB78-1112 0.33 Diorite Kellys Mountain Dioritic Rocks SB78-1129 0.71 Porphyritic diorite Kellys Mountain Dioritic Rocks SB78-1105 0.91 Diorite Kellys Mountain Dioritic Rocks SB78-1128 0.92 Diorite Kellys Mountain Dioritic Rocks SB78-1107 1.03 Biotite monzonite Kellys Mountain Dioritic Rocks SB78-1135 1.07 Quartz monzonite Kellys Mountain Dioritic Rocks SB78-1037 1.43 Fg diorite, monzonite Kellys Mountain Dioritic Rocks SB78-1132 1.61 Medium grained diorite Kellys Mountain Dioritic Rocks SB78-1041 1.82 Diorite Kellys Mountain Dioritic Rocks SB78-1040 2.50 Granodiorite Kellys Mountain Dioritic Rocks SB78-1113 2.51 Diorite and granite Kellys Mountain Dioritic Rocks SB78-1091 3.52 Hornblende diorite Kellys Mountain Dioritic Rocks SB78-1104 3.70 Granite Kellys Mountain Dioritic Rocks SB78-1106 5.33 Foliated tonalite Kellys Mountain Dioritic Rocks SB78-1005 5.97 Biotite-rich diorite Kellys Mountain Dioritic Rocks SB78-1108 10.17 Red granite Kellys Mountain Dioritic Rocks SB78-1220 10.35 Diorite, monzodiorite Kellys Mountain Dioritic Rocks SB78-1115 13.63 Altered, fractured diorite Kellys Mountain Dioritic Rocks SB78-1006 16.37 Pink cg granite (alaskite) Kellys Mountain Dioritic Rocks SB78-1096 17.33 Biotite monzodiorite Kellys Mountain Dioritic Rocks SB78-1137 19.27 Fine grained diorite Kellys Mountain Dioritic Rocks SB78-1095 24.53 Monzodiorite Kellys Mountain Dioritic Rocks SB78-1004 25.50 Diorite Kellys Mountain Dioritic Rocks SB78-1116 25.57 Diorite Kellys Mountain Dioritic Rocks SB78-1094 26.10 Diorite Kellys Mountain Dioritic Rocks SB78-1001 37.27 Melanodiorite Kellys Mountain Dioritic Rocks n = 29 8.96
SB-84-033A 0.08 Amphibolite McMillan FF-Mid Clastic Member SB-84-033B 0.29 Amphibolite McMillan FF-Mid Clastic Member K09-S66 0.33 Amphibolite McMillan Flowage Formation SB-84-050 0.58 Amphibolite McMillan FF-Mid Clastic Member RW047 0.75 Amphibolite McMillan FF - Mid Clastic Member RR84-034 0.76 Amphibolite McMillan Flowage Formation RW007 6.71 Amphibolite McMillan FF - Mid Clastic Member AM84-093 7.32 Amphibolite bands McMillan Flowage Formation RR84-060 0.77 Amphibolite/diorite? McMillan Flowage Formation SB-84-044 0.22 Amphibolite? McMillan FF - Mid Clastic Member SB-84-107 0.03 Black qtzite McMillan FF - Lower Clastic Member RW089 0.15 Black slate McMillan FF - Mid Clastic Member SB-84-035A 0.08 Blue quartzite McMillan FF - Quartzite Member RW081 0.06 Brecciated quartzite McMillan FF - Marble Member RW091 0.77 Brecciated slate McMillan FF - Mid Clastic Member RR86-2577 0.03 Slate McMillan Flowage Formation RW008 0.64 Contact rock McMillan FF - Mid Clastic Member 180
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit RW094 2.68 Biotite phyllite McMillan FF - Mid Clastic Member RW082 0.25 Garnet-mica schist McMillan FF - Mid Clastic Member RR84-037 1.27 Amphibolite McMillan Flowage Formation RR87-5538 7.40 Amphibolite McMillan Flowage Formation AM84-040B 0.22 Dolomitic marble McMillan Flowage Formation SB-84-038 0.22 Fg chloritic amphibolite McMillan FF - Quartzite Member SB-84-140 0.36 Fg chloritic schist McMillan FF - Mid Clastic Member K09-S83 4.95 Fg-mg hornblendite McMillan Flowage Formation RW033 0.54 Foliated amphibolite McMillan FF - Roper Brook Amphibolite RW055 0.28 Garnet-biotite schist McMillan FF - Marble Member RW015 0.37 Garnet mica schist McMillan FF - Mid Clastic Member RW014 0.50 Garnet mica schist McMillan FF - Mid Clastic Member RW011 0.12 Garnet pelite McMillan FF - Marble Member RW061 0.42 Garnet-rich pelite McMillan FF - Marble Memberer RW057 0.35 Garnet-rich marble/gneiss McMillan FF - Marble Member RW095 0.20 Garnet schist McMillan FF - Mid Clastic Member RW073 22.73 Semipelitic gneiss McMillan FF - Marble Member AM84-043A 0.04 Gneiss McMillan Flowage Formation RR89-7134 0.35 Gneiss McMillan Flowage Formation K09-S82 1.91 Gneiss McMillan Flowage Formation RR89-7133 6.64 Gneiss McMillan Flowage Formation K09-S121 6.17 Gneiss McMillan FF - Mid Clastic Member SB-84-023 0.23 Gneissic layer McMillan FF - Lower Clastic Member K09-S66A 0.70 Gneissic rock McMillan Flowage Formation 78-K07A-1575 21.43 Granodiorite McMillan Flowage Formation RR86-2575 0.03 Green-gray slate McMillan Flowage Formation RW092 0.95 Greenstone McMillan FF - Mid Clastic Member RW093 0.33 Greenstone w/ epidote McMillan FF - Mid Clastic Member RW078 0.37 Greenstone McMillan FF - Mid Clastic Member RW079 0.13 Grey green slate McMillan FF - Mid Clastic Member RR84-032 0.43 Hornblende schist McMillan Flowage Formation AM84-040A 25.27 Impure marble McMillan Flowage Formation SB-84-139B 0.04 Qtzite and schist McMillan FF - Mid Clastic Member SB-84-139A 0.05 Qtzite and schist McMillan FF - Mid Clastic Member SB-84-139C 0.16 Qtzite and schist McMillan FF - Mid Clastic Member K10-S14 13.97 Mafic schist McMillan FF - Mid Clastic Member RW010 2.16 Calc-sil in marble McMillan FF - Marble Member RR84-033 0.19 Mafic schist & pelitic McMillan Flowage Formation RW006 0.03 Marble McMillan FF - Mid Clastic Member RW083 0.01 Marble McMillan FF - Marble Member RW060 0.10 Marble McMillan FF - Marble Member RW059 0.08 Marble McMillan FF - Marble Member SB-84-105 0.07 Marble McMillan FF - Lower Clastic Member KL97-011 0.21 Metasiltstone McMillan Flowage Formation RR85-2205 0.08 Mica schist McMillan Flowage Formation RR85-2204 0.26 Mica schist McMillan Flowage Formation K09-S68 10.42 Mica schist McMillan Flowage Formation RR84-031 0.12 Micaceous black pelite McMillan Flowage Formation K09-S63 4.14 Micaceous diorite McMillan Flowage Formation AM84-043B 0.31 Migmatite, amphibolitic McMillan Flowage Formation AM84-042 0.11 Migmatitic gneiss McMillan Flowage Formation 181
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit AM84-039 0.23 Muscovite schist McMillan Flowage Formation RW087 0.42 Mylonite McMillan FF - Mid Clastic Member CF88-502 0.29 Mylontinized diorite McMillan Flowage Formation RW070 0.26 Paragneiss McMillan FF - Mid Clastic Member SB-84-035 0.21 Pelitic schist McMillan FF - Quartzite Member SB-84-034 0.23 Calc-silicate McMillan FF - Quartzite Member RR85-2209 0.76 Phyllitic-quartzite McMillan Flowage Formation AM84-038 0.25 Quartz mica schist McMillan Flowage Formation RW056 0.02 Quartzite McMillan FF - Marble Memberer RW080 0.04 Quartzite McMillan FF - Marble Member RR84-069 0.04 Quartzite McMillan Flowage Formation SB-84-106 0.05 Quartzite McMillan FF - Lower Clastic Member RR84-113 0.25 Quartzite McMillan Flowage Formation RW013 0.02 Quartzite w/ garnet McMillan FF - Mid Clastic Member RR89-7132 17.27 Quartzitic gneiss McMillan Flowage Formation RW096 3.89 Schist McMillan FF - Mid Clastic Member AM84-037 0.56 Schist McMillan Flowage Formation RR87-5619 9.77 Schist/migmatite McMillan Flowage Formation RW072 0.28 Semipelitic gneiss McMillan FF - Mid Clastic Member RW074 0.47 Semipelitic gneiss McMillan FF - Upper Clastic Member RW039 1.49 Semipelitic gneiss McMillan FF - Mid Clastic Member RW071 8.21 Semipelitic gneiss McMillan FF - Mid Clastic Member RW040 0.16 Semipelitic gneiss McMillan FF - Mid Clastic Member RW058 0.06 Serpentinite McMillan FF - Marble Member RR87-5539 0.22 Sheared amphibolite McMillan Flowage Formation RW077 0.14 Sheared mylonite McMillan FF - Mid Clastic Member SB-84-030 7.26 Porphyry sill McMillan FF-Mid Clastic Member RW090 0.29 Siltstone McMillan FF - Mid Clastic Member RR86-2578 0.17 Slate McMillan Flowage Formation RR86-2576 0.18 Slate, prominent veins McMillan Flowage Formation SB-84-036 0.08 Granite sheet McMillan FF - Quartzite Member SB-84-032 0.07 Typical quartzite McMillan FF-Mid Clastic Member RW088 4.73 Very slaty greenstone McMillan FF - Mid Clastic Member K10-S25 0.02 Quartzite McMillan Flowage Formation K10-S22 0.12 Cg marble McMillan Flowage Formation K10-S26 0.14 Calc silicate in quartzite McMillan Flowage Formation 104 2.10
K1-1050 2.63 0.07 Syenogranite Mount Cameron Pluton K1-1110 2.75 0.02 Syenogranite Mount Cameron Pluton K1-1102 2.55 0.03 Syenogranite Mount Cameron Pluton K1-1311 2.83 0.04 Syenogranite Mount Cameron Pluton K1-1133 2.54 0.05 Syenogranite Mount Cameron Pluton K1-1059 3.06 0.08 Syenogranite Mount Cameron Pluton K1-1135 2.69 0.08 Syenogranite Mount Cameron Pluton K1-1109 2.55 0.12 Syenogranite Mount Cameron Pluton K1-1082 3.049 0.41 Diorite Mount Cameron Pluton K1-1103 2.49 0.61 Syenogranite Mount Cameron Pluton K1-1053 2.96 0.88 Syenogranite Mount Cameron Pluton K1-1083 3.533 1.74 Diorite Mount Cameron Pluton K1-1084 2.593 4.16 Biotite granodiorite Mount Cameron Pluton 182
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit K1-1114 2.78 10.88 Syenogranite Mount Cameron Pluton K1-1105 2.66 20.41 Syenogranite Mount Cameron Pluton n = 15 2.78 2.64
F15-1564 2.47 4.80 Biotite granodiorite Shunacadie Pluton F15-1555 2.50 0.07 Biotite granodiorite Shunacadie Pluton K1-1210 2.51 2.07 Biotite granodiorite Shunacadie Pluton F15-1529 2.52 0.54 Biotite granodiorite Shunacadie Pluton BHC91-132 2.52 0.03 Granite Shunacadie Pluton F15-1539 2.55 11.66 Biotite granodiorite Shunacadie Pluton F15-1549 2.55 14.76 Biotite granodiorite Shunacadie Pluton K2-1518A 2.56 0.06 Leucogranite Shunacadie Pluton BHC92-206 2.56 4.61 Granite Shunacadie Pluton F15-1556 2.58 10.05 Biotite granodiorite Shunacadie Pluton K2-1511 2.58 5.05 Biotite granodiorite Shunacadie Pluton BHC92-200 2.58 0.24 Granodiorite Shunacadie Pluton K1-1206 2.59 0.29 Biotite granodiorite Shunacadie Pluton F15-1545 2.60 2.48 Biotite granodiorite Shunacadie Pluton F15-1548 2.60 0.24 Biotite granodiorite Shunacadie Pluton K2-1584 2.62 8.87 Biotite granodiorite Shunacadie Pluton K1-1211 2.63 3.42 Biotite granodiorite Shunacadie Pluton F15-1547 2.63 0.11 Leucogranite Shunacadie Pluton F15-1571 2.64 1.30 Biotite granodiorite Shunacadie Pluton K2-1505 2.64 10.86 Biotite granodiorite Shunacadie Pluton K2-1517 2.67 1.15 Biotite granodiorite Shunacadie Pluton BHC91-150 2.67 0.18 Granodiorite Shunacadie Pluton K2-1585 2.68 1.71 Biotite granodiorite Shunacadie Pluton K2-1516 2.68 1.29 Biotite granodiorite Shunacadie Pluton K2-1513 2.69 0.03 Biotite granodiorite Shunacadie Pluton F15-1572 2.69 17.55 Biotite granodiorite Shunacadie Pluton F15-1523 2.69 16.26 Biotite granodiorite Shunacadie Pluton K2-1512 2.70 2.58 Biotite granodiorite Shunacadie Pluton K2-1514 2.72 3.00 Biotite granodiorite Shunacadie Pluton K2-1586 2.74 0.42 Biotite granodiorite Shunacadie Pluton K2-1518B 2.75 0.04 Leucogranite Shunacadie Pluton F15-1550 2.75 0.07 Biotite granodiorite Shunacadie Pluton CCB90-62 2.75 0.13 Granite Shunacadie Pluton K2-1510 2.75 4.99 Biotite granodiorite Shunacadie Pluton F15-1546 2.76 10.77 Biotite granodiorite Shunacadie Pluton BHC91-149 2.76 0.14 Granodiorite Shunacadie Pluton F15-1557 2.76 7.07 Biotite granodiorite Shunacadie Pluton K2-1509 2.76 6.59 Biotite granodiorite Shunacadie Pluton K2-1587 2.76 0.05 Biotite granodiorite Shunacadie Pluton F15-1537 2.78 9.41 Hornblende granodiorite Shunacadie Pluton F15-1528 2.78 0.14 Biotite granodiorite Shunacadie Pluton K2-1504 2.79 1.00 Biotite granodiorite Shunacadie Pluton K2-1503 2.80 1.67 Biotite granodiorite Shunacadie Pluton F15-1565 2.80 3.41 Biotite granodiorite Shunacadie Pluton K2-1500 2.81 0.89 Biotite granodiorite Shunacadie Pluton K2-1502 2.82 3.95 Biotite granodiorite Shunacadie Pluton F15-1569 2.82 9.65 Biotite granodiorite Shunacadie Pluton 183
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit K2-1501 2.86 0.02 Biotite granodiorite Shunacadie Pluton K1-1470 2.86 3.35 Granite Shunacadie Pluton K2-1583 2.90 1.07 Granite Shunacadie Pluton F15-1566 2.91 4.15 Microgranite Shunacadie Pluton F15-1570 3.03 25.95 Diorite Shunacadie Pluton K2-1507 3.08 1.45 Biotite granodiorite Shunacadie Pluton F15-1536 3.13 9.22 Hornblende granodiorite Shunacadie Pluton n = 55 2.71 4.27
CF88-155 0.52 Diorite Timber Lake Dioritic Suite RR84-070 1.03 Diorite Timber Lake Dioritic Suite AM84-094 10.10 Bi-hbl granodiorite Timber Lake Dioritic Suite CF88-402 59.67 Diorite Timber Lake Dioritic Suite n = 4 17.83
RR84-005 0.05 Fine grained granite Wreck Cove Dioritic Suite RR84-012 0.06 Microgranite Wreck Cove Dioritic Suite 78-K09B-1525 0.14 Diorite Wreck Cove Dioritic Suite 78-K09B-1516 0.15 Diorite Wreck Cove Dioritic Suite 78-K09B-1554 0.33 Diorite Wreck Cove Dioritic Suite K9-A010A 0.38 Granite Wreck Cove Dioritic Suite K9-A035 0.40 Granodiorite Wreck Cove Dioritic Suite 78-K09B-1757 0.67 Diorite Wreck Cove Dioritic Suite 78-K09B-1755 0.71 Diorite Wreck Cove Dioritic Suite K09-S72 0.73 Granite Wreck Cove Dioritic Suite 78-K09B-1519 0.97 Diorite Wreck Cove Dioritic Suite K09-S74 1.21 Diorite Wreck Cove Dioritic Suite 78-K09B-1528 1.22 Diorite Wreck Cove Dioritic Suite 78-K09B-1527 1.29 Diorite Wreck Cove Dioritic Suite 78-K09B-1756 1.32 Diorite Wreck Cove Dioritic Suite K9-A011 1.48 Biotite granodiorite Wreck Cove Dioritic Suite 78-K09B-1515 1.52 Granite Wreck Cove Dioritic Suite RR84-078 1.90 Granite Wreck Cove Dioritic Suite 78-K09B-1531 2.68 Diorite Wreck Cove Dioritic Suite 78-K09B-1501 3.00 Diorite Wreck Cove Dioritic Suite 78-K09B-1517 3.68 Diorite Wreck Cove Dioritic Suite 78-K09B-1556 4.64 Diorite Wreck Cove Dioritic Suite K9-A012 5.06 Leuco-granodiorite Wreck Cove Dioritic Suite K09-S80 5.45 Biotite granite Wreck Cove Dioritic Suite K9-A006 5.57 Granitoid Wreck Cove Dioritic Suite K09-S130 7.23 Granodiorite Wreck Cove Dioritic Suite K09-S125 8.25 Diorite Wreck Cove Dioritic Suite 78-K09B-1502 9.31 Diorite Wreck Cove Dioritic Suite K09-S75 9.35 Cg granodiorite Wreck Cove Dioritic Suite K09-S78 9.35 Cg leucogranite Wreck Cove Dioritic Suite K09-S129 9.51 Leucocratic granodiorite Wreck Cove Dioritic Suite K9-A016 9.94 Granodiorite Wreck Cove Dioritic Suite K09-S79 10.39 Granite Wreck Cove Dioritic Suite 78-K09B-1758 10.60 Diorite Wreck Cove Dioritic Suite 78-K09B-1553 10.67 Diorite Wreck Cove Dioritic Suite K9-A037 10.70 Granodiorite porphyry Wreck Cove Dioritic Suite 184
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit 78-K09B-1529 11.03 Diorite Wreck Cove Dioritic Suite K9-A014 11.70 Granitoid Wreck Cove Dioritic Suite K9-A041 13.93 Monzonite Wreck Cove Dioritic Suite K09-S77 16.67 F-mg unfoliated diorite Wreck Cove Dioritic Suite 78-K09B-1521 17.37 Diorite Wreck Cove Dioritic Suite 78-K09B-1530 17.73 Diorite Wreck Cove Dioritic Suite K09-S71 18.80 Veined diorite Wreck Cove Dioritic Suite K9-A015 21.87 Granodiorite Wreck Cove Dioritic Suite K9-A036 22.13 Granodiorite Wreck Cove Dioritic Suite K9-A038 22.93 Granodiorite Wreck Cove Dioritic Suite K9-A007 23.60 Granitoid Wreck Cove Dioritic Suite 78-K09B-1526 26.87 Diorite Wreck Cove Dioritic Suite K9-A013 29.87 Granite Wreck Cove Dioritic Suite 78-K09B-1550 32.43 Diorite Wreck Cove Dioritic Suite 78-K09B-1520 38.83 Diorite Wreck Cove Dioritic Suite 78-K09B-1518 42.37 Diorite Wreck Cove Dioritic Suite 78-K09B-1532 43.77 Diorite Wreck Cove Dioritic Suite 78-K09B-1546 0.16 Diorite Middle Head Leucodiorite 78-K09B-1574 0.31 Diorite Middle Head Leucodiorite 78-K09B-1547 0.45 Diorite Middle Head Leucodiorite 78-K09B-1575 0.57 Diorite Middle Head Leucodiorite K09-S119 1.56 Diorite Middle Head Leucodiorite 78-K09B-1570 2.99 Diorite Middle Head Leucodiorite 78-K09B-1548 54.50 Diorite Middle Head Leucodiorite n = 60 10.37
ASPY TERRANE UNITS CW86-3605 0.01 Mg granite Black Brook Granitic Suite WY-86-4166a 0.01 Granite Black Brook Granitic Suite SB78-K16 1102 0.01 Muscovite granite Black Brook Granitic Suite SB78-K16 1117 0.01 Biotite-muscovite granite Black Brook Granitic Suite WY-86-4100B 0.01 Bioitite-rich granite Black Brook Granitic Suite WY-86-4168 0.01 Granite Black Brook Granitic Suite CW86-3662 0.02 Granite Black Brook Granitic Suite SB78-K16 1028 0.02 Granite Black Brook Granitic Suite WY-86-4099B 0.02 Biotite granite Black Brook Granitic Suite CW86-3658 0.02 Mg granite Black Brook Granitic Suite SB78-K16 1035 0.02 Granite Black Brook Granitic Suite SB78-K16 1052 0.02 Mg pink granite Black Brook Granitic Suite SB78-K16 1070 0.02 Biotite granite Black Brook Granitic Suite SB78-K16 1119 0.02 Diorite Black Brook Granitic Suite SB78-K16 1050 0.02 Granite Black Brook Granitic Suite SB78-K16 1087 0.02 Monzonite Black Brook Granitic Suite WY-86-4165 0.02 Granite Black Brook Granitic Suite CW86-3657 0.03 Granite Black Brook Granitic Suite SB78-K16 1053 0.03 Granite Black Brook Granitic Suite SB78-K16 1062 0.03 Granite Black Brook Granitic Suite SB78-K16 1088 0.03 Granite Black Brook Granitic Suite WY-86-4167 0.03 Granite Black Brook Granitic Suite CW86-3672 0.03 Pegmatite Black Brook Granitic Suite WY-86-4118 0.03 Granite Black Brook Granitic Suite 185
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit WY-86-4133A 0.03 Granite Black Brook Granitic Suite WY-86-4078 0.03 Biotite granite Black Brook Granitic Suite WY-86-4081-A 0.03 Fol granite Black Brook Granitic Suite CW86-3609 0.03 Granite Black Brook Granitic Suite RR86-2562 0.03 Granite Black Brook Granitic Suite WY-86-4091B 0.03 Granite Black Brook Granitic Suite CW86-3693 0.03 Granite Black Brook Granitic Suite RR86-2559 0.03 Pink leucrocratic granite Black Brook Granitic Suite SB78-K16 1029 0.03 Garnet-bearing granite Black Brook Granitic Suite SB78-K16 1076 0.03 Granite with pegmatite Black Brook Granitic Suite SB78-K16 1103 0.03 Granite Black Brook Granitic Suite SB78-K16 1120 0.03 Granite Black Brook Granitic Suite WY-86-4101A 0.03 Granite Black Brook Granitic Suite WY-86-4107 0.03 Granite Black Brook Granitic Suite SB78-K16 1033 0.04 Granite Black Brook Granitic Suite WY-86-4151 0.04 Muscovite-biotite granite Black Brook Granitic Suite RR86-2565 0.04 Granite Black Brook Granitic Suite WY-86-4126 0.04 Granite Black Brook Granitic Suite WY-86-4143 0.04 Fg granite Black Brook Granitic Suite RR86-2640 0.04 Biotite granite Black Brook Granitic Suite CW86-3689A 0.04 Muscovite granite Black Brook Granitic Suite WY-86-4117 0.04 Granite Black Brook Granitic Suite CW86-3540 0.04 Fg granite Black Brook Granitic Suite SB78-K16 1034 0.04 Pegmatitic granite Black Brook Granitic Suite WY-86-4147 0.04 Granite Black Brook Granitic Suite WY-86-4172 0.04 Granite Black Brook Granitic Suite WY-86-4077-A 0.04 Granite Black Brook Granitic Suite WY-86-4086 0.04 Mg biotite granite Black Brook Granitic Suite CW86-3613 0.04 Muscovite-biotite granite Black Brook Granitic Suite WY-86-4114 0.04 Coarse biotite granite Black Brook Granitic Suite SB78-K16 1030 0.04 Granite Black Brook Granitic Suite SB78-K16 1031 0.04 Granite Black Brook Granitic Suite WY-86-4008 0.04 Two mica granite Black Brook Granitic Suite WY-86-4088A 0.04 Granite Black Brook Granitic Suite WY-86-4089 0.04 Granite Black Brook Granitic Suite WY-86-4090 0.04 Granite Black Brook Granitic Suite WY-86-4169 0.04 Granite Black Brook Granitic Suite WY-86-4170 0.04 Granite Black Brook Granitic Suite CW86-3555 0.05 Muscovite-rich granite Black Brook Granitic Suite SB86-3130 0.05 Granite Black Brook Granitic Suite WY-86-4112 0.05 Granite Black Brook Granitic Suite SB78-K16 1051 0.05 Granite Black Brook Granitic Suite WY-86-4046 0.05 Mg biotite granite Black Brook Granitic Suite WY-86-4070 0.05 Granite Black Brook Granitic Suite WY-86-4091A 0.05 Granite Black Brook Granitic Suite WY-86-4125 0.05 Granite cut by pegmatite Black Brook Granitic Suite WY-86-4150A 0.05 Granite Black Brook Granitic Suite WY-86-4076 0.05 Mg biotite granite Black Brook Granitic Suite SB86-3143 0.05 Granite Black Brook Granitic Suite WY-86-4069 0.05 Mg foliated granite Black Brook Granitic Suite WY-86-4039 0.05 Fg pink biotite granite Black Brook Granitic Suite 186
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit WY-86-4047 0.05 Mg biotite granite Black Brook Granitic Suite WY-86-4123 0.05 Biotite schist Black Brook Granitic Suite WY-86-4127 0.05 Granite Black Brook Granitic Suite WY-86-4135 0.05 Granite Black Brook Granitic Suite CW86-3664 0.05 Fg biotite-musc granite Black Brook Granitic Suite CW86-3682 0.05 Mg granite Black Brook Granitic Suite WY-86-4068 0.05 Fg foliated bt granite Black Brook Granitic Suite WY-86-4145 0.05 Granite Black Brook Granitic Suite RW016 0.06 Pink granite with chlorite Black Brook Granitic Suite SB86-3129 0.06 Red biot-rich granite Black Brook Granitic Suite SB78-K16 1036 0.06 Granite Black Brook Granitic Suite RR86-2647 0.06 Granite Black Brook Granitic Suite SB78-K16 1061 0.06 Granite Black Brook Granitic Suite SB78-K16 1101 0.06 Granite with biotite Black Brook Granitic Suite WY-86-4043 0.06 Mg biotite granite Black Brook Granitic Suite WY-86-4049B 0.06 Cg granite Black Brook Granitic Suite WY-86-4141A 0.06 Granite Black Brook Granitic Suite WY-86-4087 0.06 Cg biotite granite Black Brook Granitic Suite SB86-3169 0.06 Biotite granite Black Brook Granitic Suite SB86-3170A 0.06 Fg biotite granite Black Brook Granitic Suite WY-86-4140B 0.06 Granitoid inclusion Black Brook Granitic Suite WY-86-4083 0.06 Biotite granite Black Brook Granitic Suite SB78-K16 1097 0.06 Fg granite- quite mafic Black Brook Granitic Suite SB78-K16 1115 0.06 Monzonite Black Brook Granitic Suite WY-86-4040 0.06 Cg biotite granite Black Brook Granitic Suite WY-86-4048 0.06 Granodiorite/granite Black Brook Granitic Suite WY-86-4093 0.06 Granite Black Brook Granitic Suite WY-86-4085 0.06 Granite Black Brook Granitic Suite RR86-2644 0.07 Granite Black Brook Granitic Suite SB78-K16 1094 0.07 Granite Black Brook Granitic Suite WY-86-4095 0.07 Biotite granite Black Brook Granitic Suite WY-86-4132 0.07 Biotite granite Black Brook Granitic Suite WY-86-4073 0.07 Biotite-muscovite granite Black Brook Granitic Suite CW86-3661 0.07 Granite Black Brook Granitic Suite SB86-3164 0.07 Granite Black Brook Granitic Suite WY-86-4115 0.07 Granite Black Brook Granitic Suite CW86-3545 0.07 Granite Black Brook Granitic Suite SB78-K16 1126 0.07 Granite Black Brook Granitic Suite SB78-K16 1127 0.07 Mg biotite granite Black Brook Granitic Suite WY-86-4013 0.07 Biotite granite Black Brook Granitic Suite WY-86-4171A 0.07 Granite Black Brook Granitic Suite CW86-3685 0.08 Granite Black Brook Granitic Suite CW86-3587 0.08 Mg granite Black Brook Granitic Suite WY-86-4041 0.08 Mg biotite granite Black Brook Granitic Suite WY-86-4164 0.08 Mg biotite gneiss Black Brook Granitic Suite CW86-3660 0.08 Mg granite Black Brook Granitic Suite WY-86-4113 0.08 Granodiorite/granite Black Brook Granitic Suite CW86-3600 0.08 Mg musc granite Black Brook Granitic Suite SB78-K16 1116 0.08 Granite Black Brook Granitic Suite WY-86-4002 0.08 Mg biotite granite Black Brook Granitic Suite WY-86-4074-A 0.09 Granite Black Brook Granitic Suite 187
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW86-3596 0.09 Mica schist Black Brook Granitic Suite SB86-3064 0.09 Granite Black Brook Granitic Suite CW86-3663 0.09 Granite Black Brook Granitic Suite SB86-3090 0.09 Mg biotite granite Black Brook Granitic Suite WY-86-4106 0.09 Granite Black Brook Granitic Suite RR86-2570 0.10 Granite Black Brook Granitic Suite WY-86-4119 0.10 Mg biotite granite Black Brook Granitic Suite WY-86-4094 0.10 Biotite granodiorite Black Brook Granitic Suite WY-86-4044 0.10 Cg biotite granite Black Brook Granitic Suite SB78-K16 1040 0.10 Pink mg granite Black Brook Granitic Suite SB86-3025 0.10 Granite + mafic xenos Black Brook Granitic Suite SB78-K16 1038 0.11 Pink granite Black Brook Granitic Suite SB86-3163B 0.11 Pegmatite Black Brook Granitic Suite WY-86-4104 0.11 Granite Black Brook Granitic Suite CW86-3665 0.11 Mg granite Black Brook Granitic Suite WY-86-4105 0.12 Granite Black Brook Granitic Suite SB86-3171 0.12 Biotite granite Black Brook Granitic Suite SB78-K16 1039 0.13 Pink fg-mg granite Black Brook Granitic Suite WY-86-4042 0.13 Granite Black Brook Granitic Suite WY-86-4120A 0.13 Biotite granite Black Brook Granitic Suite WY-86-4149 0.15 Granite with xenoliths Black Brook Granitic Suite SB86-3091 0.15 Musc-biotite granite Black Brook Granitic Suite WY-86-4082 0.16 Mg biotite granite Black Brook Granitic Suite WY-86-4081-B 0.17 Biotite gneiss Black Brook Granitic Suite CW86-3602 0.19 Cg granite Black Brook Granitic Suite WY-86-4072 0.21 Muscovite-biotite granite Black Brook Granitic Suite WY-86-4128 0.21 Granite + xenoliths Black Brook Granitic Suite SB86-3059 0.22 Granite Black Brook Granitic Suite WY-86-4121A 0.27 Granite Black Brook Granitic Suite RW076 0.29 Granite Black Brook Granitic Suite CW86-3659 0.65 Mg biotite granite Black Brook Granitic Suite CW86-3656 1.20 Granite Black Brook Granitic Suite SB86-3153 1.37 Granite Black Brook Granitic Suite CW86-3669 2.18 Granite Black Brook Granitic Suite SB86-3145 2.21 Granite Black Brook Granitic Suite CW86-3668 2.29 Granite Black Brook Granitic Suite SB-84-85 5.17 Biotite granite Black Brook Granitic Suite SB86-3082 5.27 Granodiorite Black Brook Granitic Suite WY-86-4103 5.54 Granite Black Brook Granitic Suite CW86-3670 6.03 Granite Black Brook Granitic Suite RR86-2586 16.20 Granite Black Brook Granitic Suite n = 166 0.35
SB86-3081C 0.02 Aplitic biotite granite Cameron Brook Granodiorite SB86-3074 0.06 Mg pink biotite granite Cameron Brook Granodiorite CW86-3644 0.07 Megacrystic granite Cameron Brook Granodiorite CW86-3648 0.07 Biotite granite Cameron Brook Granodiorite K09-S112 0.11 Granitoid Cameron Brook Granodiorite SB86-3083 0.13 Vcg megacrystic granodioriteCameron Brook Granodiorite SB86-3083 0.13 Vcg megacrystic granodioriteCameron Brook Granodiorite SB86-3079 0.34 Vcg biotite granite Cameron Brook Granodiorite 188
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW86-3649 0.41 Megacrystic granite Cameron Brook Granodiorite RR86-2556 0.80 Granite Cameron Brook Granodiorite RR86-2557 1.41 Granite Cameron Brook Granodiorite SB86-3080 1.78 Granodiorite Cameron Brook Granodiorite SB86-3078 2.15 Biotite granite Cameron Brook Granodiorite SB86-3075 2.29 Cg pink bi granite Cameron Brook Granodiorite CW86-3652 2.75 Megacrystic granite Cameron Brook Granodiorite SB86-3081A 2.79 Biotite-hornblende granodioriteCameron Brook Granodiorite RR86-2554 3.22 Granite Cameron Brook Granodiorite SB86-3119 4.04 Granodiorite Cameron Brook Granodiorite RR86-2552 4.14 Granite Cameron Brook Granodiorite CW86-3654 4.22 Granite Cameron Brook Granodiorite CW86-3651 4.30 Megacrystic granite Cameron Brook Granodiorite RR86-2553 5.01 Granite Cameron Brook Granodiorite CW86-3650 5.32 Megacrystic granite Cameron Brook Granodiorite CW86-3645 5.77 Megacrystic granite Cameron Brook Granodiorite SB86-3087 7.14 Granodiorite Cameron Brook Granodiorite SB86-3087 7.14 Granodiorite Cameron Brook Granodiorite K09-S107 11.40 Granite sheet Cameron Brook Granodiorite K09-S108 11.60 Grey massive fg diorite float Cameron Brook Granodiorite K09-S106 12.27 Gneissic diorite Cameron Brook Granodiorite n = 29 3.48
BM91-0631 0.05 Quartzite Cape North Group RR85-2010 0.05 Coarse grained granite Cape North Group CW86-3711 0.05 Felsic gneiss Cape North Group RR85-2146 0.06 Schist Cape North Group CW86-3708 0.06 Chlorite schist Cape North Group RR86-2520 0.06 Gneiss Cape North Group CW85-0013 0.06 Granite Cape North Group RR89-7054 0.09 Brecciated rock Cape North Group CW85-0010 0.09 Felsic granodioritic gneiss Cape North Group BM91-0632 0.10 Granitc gneiss Cape North Group RR85-2017 0.11 Fresh anorthosite Cape North Group RR85-2020 0.11 Typical gneiss Cape North Group CW85-0061 0.11 Granodiorite Cape North Group K16-1073 0.12 Amphibolite Cape North Group CW85-0058 0.15 Diorite Cape North Group SB85-1008C 0.16 Typical chloritic phyllite Cape North Group CW85-0007 0.17 Mafic gneiss Cape North Group FD85-0517 0.18 Biotite gneiss Cape North Group RR86-2544 0.19 Gneiss Cape North Group SB86-3018 0.19 Migmatite Cape North Group CW85-0012 0.20 Felsic gneiss Cape North Group CW86-3519 0.21 Mafic gneiss Cape North Group BM91-0621 0.23 Diorite Cape North Group CW85-0059 0.24 Granodioritic gneiss Cape North Group RR86-2596 0.27 Chlorite schist Cape North Group RR86-2518A 0.28 Gneiss Cape North Group RR86-2597 0.31 Chlorite schist Cape North Group CW85-0060 0.32 Felsic gneiss Cape North Group 189
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW86-3518 0.33 Granite Cape North Group FD85-0518 0.34 Granitic gneiss Cape North Group K16-1064 0.37 Amphibolite Cape North Group NO1-1162 0.38 Amphibolite Cape North Group RR89-7065 0.41 Mylonitic gneiss Cape North Group CW85-0011 0.46 Felsic gneiss Cape North Group RR86-2543B 0.51 Amphibolite Cape North Group RR85-2021 0.52 Amphibolite Cape North Group BM91-0613 0.53 Diorite Cape North Group SB85-1008D 0.62 Phyllite Cape North Group K16-0021 0.65 Amphibolite Cape North Group FD85-0520 0.70 Biotite schist Cape North Group SB85-1008B 0.72 Massive phyllite Cape North Group RR89-7061 0.78 Sheared amphibolite Cape North Group SB85-1008A 0.87 Mafic gneiss Cape North Group RR86-2670 0.97 Chloritized gneiss Cape North Group RR85-2022 1.57 Gneiss Cape North Group RR85-2059 1.81 Chloritized granodiorite Cape North Group FD85-0516 1.85 Mafic gneiss Cape North Group RR89-7072 2.58 Porphyry Cape North Group RR89-7051 3.32 Amphibolite Cape North Group BM91-0614 3.42 Anorthosite Cape North Group RR85-2064 3.62 Granodiorite Cape North Group CW85-0009 3.92 Mafic schist Cape North Group CW86-3710 5.57 Felsic gneiss Cape North Group CW85-0014 5.67 Gneiss Cape North Group RR89-7053 6.28 Interbedded felsic rocks Cape North Group RR86-2519 6.48 Garnet biotite schist Cape North Group RR85-2024 6.79 Granodioritic gneiss Cape North Group RR89-7062 6.82 Gneiss Cape North Group RR89-7052 8.52 Amphibolite Cape North Group CW85-0005 9.17 Intermediate gneiss Cape North Group BM91-0608 9.53 Syenogranitic gneiss Cape North Group RR86-2595 10.83 Granitoid gneiss Cape North Group RR85-2063 12.53 Chloritized granodiorite Cape North Group RR85-2061 12.53 Granodiorite Cape North Group CW85-0008 15.01 Garnet amphibolite Cape North Group BM91-0626 20.40 Anorthosite Cape North Group CW85-0057 22.77 Diorite Cape North Group RR85-2060 24.97 Granodiorite Cape North Group BM91-0610 28.00 Diorite Cape North Group n = 69 3.58
CW86-3530 0.01 Marble Cheticamp Lake Gneiss CW86-3533 0.01 Marble Cheticamp Lake Gneiss CW86-3584 0.02 Granite Cheticamp Lake Gneiss RR86-2614A 0.03 Gneiss Cheticamp Lake Gneiss RR86-2616 0.03 Gneiss Cheticamp Lake Gneiss RR86-2614B 0.03 Garnet-bearing gneiss Cheticamp Lake Gneiss RR86-2615 0.04 Two mica gneiss Cheticamp Lake Gneiss RW018 0.04 Semipelitic gneiss Cheticamp Lake Gneiss 190
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW86-3673 0.04 Felsic gneiss Cheticamp Lake Gneiss CW86-3675 0.04 Felsic gneiss Cheticamp Lake Gneiss RR86-2617 0.05 Gneiss Cheticamp Lake Gneiss WY-86-4006 0.05 Two mica granite/gneiss Cheticamp Lake Gneiss RR87-5520 0.06 Biotite gneiss Cheticamp Lake Gneiss RR87-5516 0.07 Biotite-rich gneiss Cheticamp Lake Gneiss WY-86-4080 0.07 Fg gneiss Cheticamp Lake Gneiss SB86-3175 0.07 Gneiss Cheticamp Lake Gneiss RW024 0.08 Semipelitic gneiss Cheticamp Lake Gneiss RW027 0.08 Felsic gneiss Cheticamp Lake Gneiss RR87-5521 0.08 Gneiss Cheticamp Lake Gneiss CW86-3528 0.11 Biotite gneiss Cheticamp Lake Gneiss SB86-3167 0.11 Biotite gneiss Cheticamp Lake Gneiss RR87-5518 0.11 Garnet semipelitic gneiss Cheticamp Lake Gneiss CW86-3666B 0.13 Amphibolite gneiss Cheticamp Lake Gneiss RW026 0.16 Grey gneiss + bt schist Cheticamp Lake Gneiss RW067 0.16 Pelitic migmatitic gneiss Cheticamp Lake Gneiss SB86-3024A 0.16 Gneiss Cheticamp Lake Gneiss RW066 0.18 Semipelitic gneiss Cheticamp Lake Gneiss SB86-3176 0.18 Gneiss Cheticamp Lake Gneiss CW86-3671 0.21 Biotite schist gneiss Cheticamp Lake Gneiss CW86-3667 0.28 Amphibolite gneiss Cheticamp Lake Gneiss CW86-3666A 0.28 Amphibolitic gneiss Cheticamp Lake Gneiss SB86-3174 0.33 Gneiss Cheticamp Lake Gneiss RR87-5517 0.35 Hbl gneiss Cheticamp Lake Gneiss RR86-2615A 0.40 Hornblende gneiss Cheticamp Lake Gneiss RW053 0.59 Pelite gneiss Cheticamp Lake Gneiss CW86-3674 0.59 Felsic gneiss Cheticamp Lake Gneiss SB86-3178 0.93 Biotite gneiss Cheticamp Lake Gneiss RW062 2.03 Pelitic gneiss Cheticamp Lake Gneiss WY-86-4079 2.16 Gneiss Cheticamp Lake Gneiss RW064 5.25 Cg semipelitic gneiss Cheticamp Lake Gneiss RR86-2639 5.58 Biotite schist Cheticamp Lake Gneiss RR86-2612 6.04 Gneiss Cheticamp Lake Gneiss RR86-2642 33.30 Hornblende gneiss Cheticamp Lake Gneiss n = 43 1.41
SB86-3109 0.01 Felsic schist Clyburn Brook Formation CW86-3616A 0.02 Metarhyolite Clyburn Brook Formation SB86-3110 0.07 Felsic schist Clyburn Brook Formation CW86-3622 0.08 Metarhyolite Clyburn Brook Formation SB86-3111 0.14 Schist/phyllite Clyburn Brook Formation CW86-3627 0.15 Black slate rich in pyrite Clyburn Brook Formation RR86-2585 0.17 Biotite schist Clyburn Brook Formation CW86-3626 0.18 Crystal lithic tuff Clyburn Brook Formation RR86-2583 0.22 Chl schist Clyburn Brook Formation SB86-3112 0.22 Felsic schist Clyburn Brook Formation SB86-3126 0.22 Gneiss w mafic schist Clyburn Brook Formation SB86-3113 0.59 Metagabbro Clyburn Brook Formation RR86-2584 0.67 Biotite schist Clyburn Brook Formation SB86-3125 10.61 Gneiss Clyburn Brook Formation 191
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit n = 14 0.95
RR86-2624 0.02 Granite Glasgow Brook Granodiorite CW86-3539 0.05 Fg pink granite Glasgow Brook Granodiorite CW86-3537 0.06 Granite Glasgow Brook Granodiorite SB86-3072 0.06 Biotite granite Glasgow Brook Granodiorite SB86-3072 0.06 Biotite granite Glasgow Brook Granodiorite SB86-3073 0.18 Gneissic granodiorite Glasgow Brook Granodiorite SB86-3073 0.18 Gneissic granodiorite Glasgow Brook Granodiorite SB86-3071 0.22 Cg biotite granodiorite Glasgow Brook Granodiorite SB86-3071 0.22 Cg biotite granodiorite Glasgow Brook Granodiorite CW86-3534 0.23 Pegmatite Glasgow Brook Granodiorite SB86-3070 0.27 Granodiorite Glasgow Brook Granodiorite SB86-3070 0.27 Granodiorite Glasgow Brook Granodiorite n = 12 0.15
SMB08-127 0.04 Grey rhyolite Ingonish Island Rhyolite RR86-2629 0.06 Rhyolite Ingonish Island Rhyolite RR86-2633 0.07 Pink rhyolitic dyke Ingonish Island Rhyolite RR86-2638 0.08 Rhyolite Ingonish Island Rhyolite SMB08-129a 0.10 Rhyolite Ingonish Island Rhyolite SMB08-128a 0.14 Rhyolite Ingonish Island Rhyolite SMB08-124a 13.51 Black rhyolite Ingonish Island Rhyolite RR86-2637 20.47 Aphanitic rhyolite Ingonish Island Rhyolite SMB08-125 40.77 Massive black rhyolite Ingonish Island Rhyolite n = 9 8.36
CW87-5012 0.01 Granite Margaree Pluton SB86-3211 0.06 Granite Margaree Pluton SB86-3210 0.09 Granite Margaree Pluton CW87-5013 0.11 Granite Margaree Pluton CW87-5009 0.13 Granite Margaree Pluton CW86-3725 0.19 Granite Margaree Pluton CW86-3726 0.21 Granite Margaree Pluton SB86-3213 0.32 Granite Margaree Pluton SB86-3158 0.32 Granite Margaree Pluton CW86-3723 0.33 Granite Margaree Pluton SB86-3157 0.34 Granite Margaree Pluton SB86-3156 0.36 Granite Margaree Pluton SB86-3155 0.41 Granite Margaree Pluton SB86-3209 0.42 Granite Margaree Pluton SB86-3212 0.47 Granite Margaree Pluton SB86-3216 0.70 Granite Margaree Pluton SB86-3214 0.84 Granite Margaree Pluton RR-86-2665 0.88 Granite Margaree Pluton SB86-3159 0.88 Granite Margaree Pluton SB86-3194-A 1.20 Granite Margaree Pluton RR-86-2666 1.47 Granite Margaree Pluton CW86-3724 1.70 Granite Margaree Pluton SB86-3154 1.84 Granite Margaree Pluton SB86-3044 2.12 Granite Margaree Pluton 192
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW86-3718 2.28 Granite Margaree Pluton CW87-5010-B 2.57 Granite Margaree Pluton CW86-3717-A 3.40 Granite Margaree Pluton SB86-3042 5.47 Granite Margaree Pluton CW87-5010-A 7.14 Granite Margaree Pluton CW87-5011 7.69 Granite Margaree Pluton SB86-3194-B 8.63 Granite Margaree Pluton SB86-3043 11.55 Granite Margaree Pluton SB86-3049 11.85 Granite Margaree Pluton CW86-3717-B 22.60 Granite Margaree Pluton n = 34 2.90
CW86-3502 0.01 Felsic intralayers Money Point Group CW86-3510 0.01 Pegmatitic Money Point Group CW85-0003 0.02 Granite Money Point Group CW86-3563B 0.02 Marble Money Point Group CW86-3520 0.02 Felsic gneiss Money Point Group CW85-0021B 0.03 Granite Money Point Group CW86-3558 0.03 Quartz-felsdspar gneiss Money Point Group CW86-3561 0.03 Felsic granitic gneiss Money Point Group RR85-2001 0.03 Granite Money Point Group RR86-2619 0.03 Pink granite-gneiss Money Point Group RR86-2514 0.03 Gneiss Money Point Group RR86-2620 0.03 Granitic gneiss Money Point Group CW86-3509 0.03 Mafic mica rich schist Money Point Group CW86-3513 0.03 Felsic gneiss Money Point Group RR86-2660 0.03 Micaceous quartzite Money Point Group SB86-3013 0.03 Granite Money Point Group CW85-0021C 0.04 Xenolith-peg/granite Money Point Group CW86-3563A 0.04 Margin of marble Money Point Group CW85-0020 0.04 Mafic schist Money Point Group SB86-3014 0.04 Granite Money Point Group CW86-3503 0.04 Mafic gneiss Money Point Group CW86-3512 0.04 Granite pegmatite Money Point Group SB86-3008 0.04 Gneiss Money Point Group NO1-1024 0.04 Rhyolite Money Point Group CW85-0026 0.05 Granite Money Point Group CW86-3516 0.05 Granite Money Point Group SB86-3012 0.05 Granite Money Point Group SB86-3007 0.05 Granite Money Point Group RR86-2621 0.06 Granitic gneiss Money Point Group SB86-3004 0.06 Red granite Money Point Group RR85-2009 0.06 Quartzite Money Point Group SB86-3017B 0.06 Marble Money Point Group RR86-2539 0.07 Garnet gneiss Money Point Group CW86-3504 0.08 Felsic gneiss Money Point Group RR86-2523 0.08 Mica schist Money Point Group SB86-3006B 0.08 Gneiss Money Point Group SB86-3006C 0.08 Marble Money Point Group RR86-2545 0.09 Quartzofeldspathic gneiss Money Point Group SB86-3016 0.09 Granite Money Point Group 193
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit RR86-2526 0.09 Mica schist cut by granite dykeMoney Point Group SB86-3005 0.09 Granite Money Point Group RR86-2609 0.10 Schist and gneiss Money Point Group CW86-3507 0.11 Quartz feldspar gneiss Money Point Group RR86-2606 0.11 Gneiss Money Point Group SB86-3002 0.12 Gneiss Money Point Group RR86-2608 0.12 Semipelitic granite Money Point Group CW86-3521 0.13 Mafic qtz-feldspar gneiss Money Point Group RR86-2515 0.14 Mica schist / gneiss Money Point Group RR86-2654 0.14 Orthogneiss Money Point Group RR86-2512 0.15 Dark mica schist Money Point Group CW85-0022 0.15 Intermediate gneiss Money Point Group CW85-0023 0.15 Intermediate gneiss Money Point Group CW86-3562 0.15 Mica schist with garnet Money Point Group CW86-3511 0.16 Gneiss Money Point Group RR86-2610 0.16 Schist Money Point Group CW85-0021A 0.17 Grantic gneiss Money Point Group CW86-3501 0.18 Mica rich schist Money Point Group RR86-2516 0.18 Gneiss Money Point Group CW86-3514 0.18 Mafic mica schist Money Point Group RR86-2525 0.18 Garnet mica schist Money Point Group CW85-0001 0.19 Schist Money Point Group RR86-2611 0.20 Amphibolite Money Point Group CW85-0019 0.21 Schist Money Point Group CW86-3508 0.22 Feldspathic gneiss Money Point Group CW86-3559 0.22 Hornblende gneiss Money Point Group RR86-2527 0.22 Mica schist Money Point Group SB86-3015 0.22 Granite Money Point Group RR85-2002 0.23 Schist Money Point Group CW85-0027 0.23 Gneiss Money Point Group CW86-3517 0.23 Mafic gneiss Money Point Group SB86-3017A 0.24 Mafic rock Money Point Group RR86-2659 0.26 Dark mica schist Money Point Group RR86-2522 0.28 Mica schist Money Point Group NO1-1142 0.28 Mafic metavolcanic Money Point Group RR86-2529 0.29 Mica schist Money Point Group RR86-2655 0.30 Garnet mica schist Money Point Group RR86-2524 0.31 Garnet mica schist Money Point Group RR86-2513 0.33 Mica schist Money Point Group CW85-0024 0.34 Mafic schist Money Point Group RR86-2517 0.37 Amphibolite Money Point Group RR86-2528 0.37 Gneissic rock Money Point Group NO1-0116 0.40 Mafic metavolcanic Money Point Group CW85-0025 0.40 Mafic schist Money Point Group NO1-0110 0.41 Mafic metavolcanic Money Point Group RR89-7056 0.42 Gneiss w/granite veins Money Point Group SB86-3006A 0.44 Amphibolite Money Point Group NO1-0023 0.45 Metatuff Money Point Group NO1-0025 0.45 Metatuff Money Point Group NO1-1143 0.49 Mafic metavolcanic Money Point Group NO1-0112 0.51 Mafic metavolcanic Money Point Group 194
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit NO1-1154 0.53 Mafic metavolcanic Money Point Group NO1-1144 0.57 Mafic metavolcanic Money Point Group NO1-0113 0.59 Mafic metavolcanic Money Point Group NO1-0133 0.66 Mafic metavolcanic Money Point Group NO1-0076 0.68 Mafic metavolcanic Money Point Group NO1-0087 0.85 Mafic metavolcanic Money Point Group RR85-2006 0.85 Granite-gneiss Money Point Group NO1-0008 0.90 Mafic metavolcanic Money Point Group NO1-1149 0.93 Mafic metavolcanic Money Point Group NO1-0053 0.97 Mafic metavolcanic Money Point Group RR86-2656 1.15 Garnet mica schist Money Point Group RR86-2658 1.19 Mica schist Money Point Group RR89-7057 1.34 Amphibolite Money Point Group NO1-0015 1.37 Rhyolite Money Point Group RR85-2004 1.62 Mafic schist Money Point Group RR86-2657 1.63 Cg biotite gneiss Money Point Group RR85-2003 1.72 Gneiss Money Point Group RR89-7050 2.56 Granite gneiss Money Point Group RR85-2007 2.71 Mafic schist Money Point Group RR85-2008 3.29 Pink gneiss Money Point Group RR89-7058 6.06 Gneiss Money Point Group NO1-0017 10.05 Mafic metavolcanic Money Point Group RR85-2005 11.17 Semipelitic gneiss or granodioriteMoney Point Group RR89-7059 14.47 Gneiss Money Point Group RR89-7055 17.93 Gneiss Money Point Group NO1-0068 23.83 Mafic metavolcanic Money Point Group RR89-7060 63.13 Amphibolite Money Point Group n = 116 1.60
SB78-K16 1064 0.11 Granite Neils Harbour Gneiss SB78-K16 1066 0.02 Granite Neils Harbour Gneiss SB78-K16 1067 0.04 Monzonite Neils Harbour Gneiss SB78-K16 1068 0.09 Diorite Neils Harbour Gneiss SB78-K16 1006 0.09 Monzonite Neils Harbour Gneiss SB78-K16 1008 0.22 Granodiorite Neils Harbour Gneiss SB78-K16 1009 0.09 Granodiorite Neils Harbour Gneiss SB78-K16 1010 0.15 Monzonite Neils Harbour Gneiss SB78-K16 1015 0.02 Mg granite Neils Harbour Gneiss SB78-K16 1016 0.02 Fg pink monzonite Neils Harbour Gneiss SB78-K16 1017 0.03 Fg pink monzonite Neils Harbour Gneiss SB78-K16 1041 0.10 Biotite granite Neils Harbour Gneiss SB78-K16 1043 0.05 Granite Neils Harbour Gneiss SB78-K16 1044 0.21 Amphibolite Neils Harbour Gneiss SB78-K16 1045 0.07 Monzonite Neils Harbour Gneiss SB78-K16 1046 0.04 Granite Neils Harbour Gneiss SB78-K16 1049 0.05 Granite Neils Harbour Gneiss SB78-K16 1055 0.03 Pink mg granite Neils Harbour Gneiss SB78-K16 1056 0.14 Diorite Neils Harbour Gneiss SB78-K16 1075 0.02 Granite with pegmatite Neils Harbour Gneiss SB78-K16 1106 0.08 Granite and pegmatite Neils Harbour Gneiss SB78-K16 1107 0.13 Pink granite Neils Harbour Gneiss 195
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit SB78-K16 1110 0.01 Monzonite and granite Neils Harbour Gneiss SB78-K16 1111 0.08 Granodiorite Neils Harbour Gneiss SB78-K16 1112 0.17 Mafic diorite band Neils Harbour Gneiss SB78-K16 1113 0.03 Alaskite Neils Harbour Gneiss WY-86-4137 0.14 Gneiss Neils Harbour Gneiss WY-86-4138A 0.03 Granite Neils Harbour Gneiss WY-86-4138B 0.10 Gneiss Neils Harbour Gneiss WY-86-4173 0.06 Gneiss Neils Harbour Gneiss WY-86-4174 0.08 Gneiss Neils Harbour Gneiss WY-86-4131B 0.12 Gneiss Neils Harbour Gneiss K09-S61 0.45 Diorite Neils Harbour Gneiss SB-84-81 0.15 Biotite granite Neils Harbour Gneiss SB-84-82 1.29 Biotite granite Neils Harbour Gneiss SB-84-83 0.21 Monzodiorite Neils Harbour Gneiss SB-84-86 16.00 Qtz monzodiorite Neils Harbour Gneiss n = 37 0.56
95-MON-354 0.01 Rhyolite Sarach Brook Metamorphic Suite 95-MON-331 0.01 Mylonite Sarach Brook Metamorphic Suite 95-MON-074 0.02 Mylonite Sarach Brook Metamorphic Suite 95-MON-010A 0.02 Felsic mylonite Sarach Brook Metamorphic Suite 95-MON-079 0.03 Mylonite Sarach Brook Metamorphic Suite KL97-069 0.03 Dacite lithic Sarch Brook Metamorphic Suite 95-MON-175 0.03 Mylonite Sarach Brook Metamorphic Suite KL97-029 0.05 Rhyolitic xtal tuff Sarach Brook Metamorphic Suite KL97-044 0.06 Metasiltstone Sarach Brook Metamorphic Suite KL97-043 0.06 Recrys rhyolite Sarach Brook Metamorphic Suite 95-MON-168 0.07 Mylonite Sarach Brook Metamorphic Suite KL97-013 0.08 Lithic tuff? Ash tuff Sarach Brook Metamorphic Suite KL97-056 0.08 Mylonite Sarach Brook Metamorphic Suite KL97-014 0.08 Thinly banded mylonite Sarach Brook Metamorphic Suite KL97-041 0.09 Lithic tuff Sarach Brook Metamorphic Suite 95-MON-176 0.09 Mafic volcanic Sarach Brook Metamorphic Suite 95-MON-080 0.09 Mylonite Sarach Brook Metamorphic Suite KL97-022 0.10 Flow banded rhyolite Sarach Brook Metamorphic Suite 95-MON-092 0.12 Mylonite Sarach Brook Metamorphic Suite 95-MON-340 0.12 Porphyry basalt Sarach Brook Metamorphic Suite KL97-039 0.13 Metasiltstone Sarach Brook Metamorphic Suite KL97-068 0.13 Dac lithic xtal tuff Sarch Brook Metamorphic Suite 95-MON-180 0.13 Mylonite Sarach Brook Metamorphic Suite KL97-010 0.14 Spotty rock Sarach Brook Metamorphic Suite KL97-059A 0.14 Schistose mafic tuff Sarach Brook Metamorphic Suite KL97-046 0.15 Amygdaloidal andesite Sarach Brook Metamorphic Suite KL97-048 0.15 Rhyolite flow Sarach Brook Metamorphic Suite 95-MON-288 0.17 Diorite/mylonite Sarach Brook Metamorphic Suite 95-MON-334 0.19 Amyg basalt Sarach Brook Metamorphic Suite KL97-047 0.19 Rhyolite, pink, flow Sarach Brook Metamorphic Suite KL97-049 0.20 Mylonitized lithic tuff Sarach Brook Metamorphic Suite KL97-030B 0.20 Metasiltstone, dark Sarach Brook Metamorphic Suite KL97-038 0.21 Amphibolite? Sarach Brook Metamorphic Suite KL97-062 0.23 Andesite lithic tuff Sarach Brook Metamorphic Suite 196
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit 95-MON-142 0.24 Metabasite Sarach Brook Metamorphic Suite KL97-024 0.24 Banded tuff Sarach Brook Metamorphic Suite KL97-050 0.25 Dark xtal tuff Sarach Brook Metamorphic Suite KL97-060 0.26 Andesite Sarach Brook Metamorphic Suite KL97-009 0.28 Amygdaloidal basalt Sarach Brook Metamorphic Suite KL97-030A 0.29 Metasiltstone, light Sarach Brook Metamorphic Suite KL97-021 0.32 Cherty bedded rock Sarach Brook Metamorphic Suite 95-MON-228 0.32 Mylonite Sarach Brook Metamorphic Suite KL97-059B 0.33 Andesite Sarach Brook Metamorphic Suite KL97-042 0.33 Andesite Sarach Brook Metamorphic Suite KL97-051 0.34 Andesite dacite xtal tuff Sarach Brook Metamorphic Suite KL97-026 0.34 Metatuff? Sarach Brook Metamorphic Suite KL97-045 0.37 Metasiltstone Sarach Brook Metamorphic Suite KL97-023 0.50 Mafic tuff or flow Sarach Brook Metamorphic Suite KL97-028B 0.51 Spotty xtal tuff Sarach Brook Metamorphic Suite KL97-025 0.61 Amygdaloidal basalt Sarach Brook Metamorphic Suite 95-MON-086 0.65 Mylonite Sarach Brook Metamorphic Suite KL97-052 2.59 Dacite ignimbrite Sarach Brook Metamorphic Suite 95-MON-296 3.71 Blastomylonite Sarach Brook Metamorphic Suite KL97-058 4.57 Laminated ash tuff Sarach Brook Metamorphic Suite KL97-040 4.67 Lithic tuff Sarach Brook Metamorphic Suite 95-MON-293 5.10 Mafic mylonite Sarach Brook Metamorphic Suite KL97-008 5.51 Rhyolitic lithic tuff Sarach Brook Metamorphic Suite KL97-057 5.80 Flow banded rhyolite Sarach Brook Metamorphic Suite 95-MON-350 6.51 Medium grained diorite Sarach Brook Metamorphic Suite KL97-053 6.76 Dacite xtal lithic tuff Sarach Brook Metamorphic Suite 95-MON-342 8.86 Medium grained gabbro Sarach Brook Metamorphic Suite 95-MON-344 11.77 Gabbro Sarach Brook Metamorphic Suite KL97-054 14.20 Coarse lithic tuff Sarach Brook Metamorphic Suite 95-MON-232 14.43 Crystal tuff Sarach Brook Metamorphic Suite KL97-027 14.43 Rhyolitic xtal tuff Sarach Brook Metamorphic Suite KL97-031 14.43 Rhyolitic xtal tuff Sarach Brook Metamorphic Suite KL97-061 49.53 Andesite Sarach Brook Metamorphic Suite n = 80 2.73
CW85-0083 0.01 Granite Wilkie Sugarloaf Granite CW85-0082 0.03 Granite Wilkie Sugarloaf Granite FD85-513A 0.03 Granite Wilkie Sugarloaf Granite FD85-505A 0.04 Muscovite-biotite granite Wilkie Sugarloaf Granite RR85-2067 0.04 Granite Wilkie Sugarloaf Granite FD85-505B 0.05 Granite Wilkie Sugarloaf Granite CW85-0084 0.11 Granite Wilkie Sugarloaf Granite CW85-0081 0.12 Schist Wilkie Sugarloaf Granite FD85-0511 0.13 Granitic gneiss Wilkie Sugarloaf Granite FD85-0515 0.21 Biotite granite Wilkie Sugarloaf Granite FD85-509B 0.22 Aplite Wilkie Sugarloaf Granite SB85-1009 0.25 Red granite Wilkie Sugarloaf Granite FD86-513B 0.26 Granite Wilkie Sugarloaf Granite FD85-508B 0.27 Amphibolite Wilkie Sugarloaf Granite CW85-0080 0.28 Granite Wilkie Sugarloaf Granite SB85-1000 0.34 Granite Wilkie SugarLoaf Granite 197
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit FD85-508A 0.42 Amphibolite Wilkie Sugarloaf Granite RR85-2027 0.50 Granite Wilkie Sugarloaf Granite FD85-0507 0.59 Biotite granite gneiss Wilkie Sugarloaf Granite FD85-0514 0.78 Granite Wilkie Sugarloaf Granite FD85-506A 1.01 Granitic gneiss Wilkie Sugarloaf Granite SB85-1137 1.58 Granite Wilkie Sugarloaf Granite RR85-2026 2.10 Granite Wilkie Sugarloaf Granite FD85-509A 3.02 Granite Wilkie Sugarloaf Granite FD85-0510 5.65 Granitic gneiss Wilkie Sugarloaf Granite n = 25 0.72
BLAIR RIVER INLIER - ANORTHOSITE AND SYENITE BM90-0128 12.47 Syenite Red Ravine Syenite BM91-0502 18.40 Syenite gneiss Red River Anorthosite Suite BM91-0504 0.53 Syenite Red Ravine Syenite BM91-0522 42.37 Anorthosite Red River Anorthosite Suite BM91-0540 4.23 Syenitic gneiss Lowland Brook Syenite BM91-0541 4.48 Syenite Lowland Brook Syenite BM91-0542 3.42 Syenitic granite Lowland Brook Syenite BM91-0543 4.06 Syenitic granite Lowland Brook Syenite BM91-0544 5.67 Syenitic granite Lowland Brook Syenite BM91-0655 1.25 Syenitic gneiss Lowland Brook Syenite BM91-0656 2.25 Syenite Lowland Brook Syenite BM91-0657 16.23 Syenitic gneiss Lowland Brook Syenite BM91-0762 16.50 Syenite gneiss Red River Anorthosite Suite BM91-RB006 0.28 Syenitic gneiss Red River Anorthosite Suite BM91-RB007 13.20 Anorthosite gabbro Red River Anorthosite Suite BM91-RB020 17.37 Syenite gneiss Red River Anorthosite Suite BM91-RB023 0.70 Anorthosite Red River Anorthosite Suite BM91-RB025 0.07 Anorthosite Red River Anorthosite Suite BM91-RB047 21.73 Syenite Red River Anorthosite Suite BM91-RB052 0.14 Anorthosite Red River Anorthosite Suite BM91-RB074 0.18 Anorthosite Red River Anorthosite Suite BM91-0663 0.04 Anorthosite Anorthosite CW85-0016 1.08 Granite Lowland Brook Syenite CW85-0017 1.00 Granite Lowland Brook Syenite CW85-0018 3.27 Granite Lowland Brook Syenite CW85-0030 0.13 Granite Lowland Brook Syenite CW85-0031 0.87 Granite Lowland Brook Syenite CW85-0065 0.15 Granite Lowland Brook Syenite CW85-0085 2.50 Syenite Lowland Brook Syenite CW85-0086 2.29 Syenite Lowland Brook Syenite CW85-0087 0.71 Syenite Lowland Brook Syenite CW85-0087A 4.39 Syenite Lowland Brook Syenite CW85-0088 8.08 Syenite Lowland Brook Syenite CW85-0089 0.95 Syenite Lowland Brook Syenite CW85-0090 6.76 Syenite Lowland Brook Syenite CW85-0091 15.53 Syenite Lowland Brook Syenite CW85-0092 2.28 Gneissic syenite Lowland Brook Syenite CW85-0108 0.45 Granite Lowland Brook Syenite 198
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit CW85-0110 2.99 Syenite Lowland Brook Syenite CW85-0111B 1.06 Syenite Lowland Brook Syenite CW85-0113 0.25 Syenite Lowland Brook Syenite CW86-3721 0.07 Anorthosite Red River Anorthosite Suite RR85-2131 0.06 Anorthosite Red River Anorthosite Suite RR85-2138 0.04 Anorthosite Red River Anorthosite Suite SB85-1045 1.31 Syenite Lowland Brook Syenite SB85-1047 4.78 Syenite Lowland Brook Syenite SB85-1048 50.57 Syenite Lowland Brook Syenite SB85-1049 2.18 Syenite Lowland Brook Syenite SB85-1121 0.03 Anorthosite Red River Anorthosite Suite SB85-1134 0.88 Anorthositic gabbro Red River Anorthosite Suite n = 49 6.00
BLAIR RIVER INLIER - GNEISSIC ROCKS CW85-0141 0.03 Felsic gneiss Otter Brook Gneiss BM90-0090 0.15 Amphibolitic gneiss Otter Brook Gneiss CW85-0156 0.22 Granitic gneiss Otter Brook Gneiss CW85-0075 0.29 Mafic gneiss Otter Brook Gneiss CW85-0142 0.34 Dioritic gneiss Otter Brook Gneiss BM91-0674 1.76 Gneiss Otter Brook Gneiss BM90-0141 3.32 Amphibolitic gneiss Otter Brook Gneiss SB85-1052 16.03 Red granite gneiss Otter Brook Gneiss BM91-0711 33.20 Qtzo-feldspathic gneiss Otter Brook Gneiss CW85-0076 47.43 Mafic gneiss Otter Brook Gneiss BM91-0709 15.17 Gneiss Otter Brook Gniess BM91-0724 21.80 Gneiss Otter Brook Gniess BM90-0094 25.97 Amphibolite gneiss Otter Brook Gniess AM85-011 0.39 Amphibolitic gneiss Pollets Cove River Gneiss AM85-021 0.87 Banded gneiss Pollets Cove River Gneiss AM85-015 11.97 Granodioritic gneiss Pollets Cove River Gneiss AM85-023B 15.80 Granodioritic gneiss Pollets Cove River Gneiss BM91-0642 0.07 Mica gneiss Polletts Cove River Gneiss SB85-1007 0.13 Grantic gneiss Polletts Cove River Gneiss CW85-0147 0.32 Felsic gneiss Polletts Cove River Gneiss BM91-0653 0.47 Gneiss Polletts Cove River Gneiss SB85-1141 1.14 Mafic gneiss Polletts Cove River Gneiss BM91-0511 1.82 Granitic biotite gneiss Polletts Cove River Gneiss BM91-0639 1.92 Mafic gneiss Polletts Cove River Gneiss SB85-1146 2.26 Monzodiorite or gneiss Polletts Cove River Gneiss BM91-0634 4.73 Grantic gneiss Polletts Cove River Gneiss BM91-0637 8.88 Qtzo-feldspathic gneiss Polletts Cove River Gneiss BM91-0638 10.70 Paragneiss Polletts Cove River Gneiss BM91-0602 15.63 Syenitic granitic gneiss Polletts Cove River Gneiss BM91-0600 22.03 Syenitic granitic gneiss Polletts Cove River Gneiss BM90-0101 41.77 Amphibolite gneiss Polletts Cove River Gneiss BM91-0738 0.20 Syenitic granite Blair River Inlier BM91-0736 0.49 Granite/diorite Blair River Inlier BM91-0740 1.87 Granite Blair River Inlier BM91-0686 3.79 Granite Blair River Inlier RR85-2075 9.27 Anorthositic gneiss Blair River Inlier 199
SAMPLE # ρ(Avg) k(Avg) Sample lithology Unit BM91-0737 20.33 Monzodiorite Blair River Inlier BM91-0739 132.67 Syenite granite Blair River Inlier n = 38 12.51
CW85-0096 0.18 Rhyolite Lowland Cove Formation n = 1 0.18 200
Appendix B. Summary of density and magnetic susceptibility data* used in this study.
Density Magnetic Susceptibility (g/cm3) (x10-3 SI units) Range Avg Range Avg n CAPE BRETON ISLAND Carboniferous Rocks Horton Group 2.27-2.96 2.54 0.03-23.5 1.17 - Mabou Group 2.15-2.68 2.47 0.14-0.22 0.17 8 Morien Group 2.19-2.52 2.35 0.11-0.29 0.17 10 Pictou Group 2.15-2.51 2.29 0.06-0.14 0.08 18 Windsor Group 2.47-2.7 2.59 0.06-0.09 0.07 5 Bras d'Or terrane Barachois River Formation 1.83-3.15 2.81 0.1-17.60 4.46 25 Benacadie Pond Formation 2.51-3.00 2.78 0.00-1.42 0.31 15 Birch Plain Granite 2.33-2.94 2.64 0.01-46.70 12.07 47 Boisdale Hills Pluton 2.44-3.24 2.82 0.02-72.75 8.21 114 Bourinot Belt 2.41-3.17 2.75 0.01-44.00 5.12 56 Cape Smokey Granite 2.33-2.94 2.64 0.04-31.83 3.16 57 Cross Mountain Granite 2.33-2.94 2.64 0.02-12.13 1.39 12 Frenchvale Road MS 2.57-2.78 2.66 0.01-10.38 0.77 25 Gisborne Flowage Quartz Diorite 2.43-3.16 2.81 0.02-0.14 0.06 1 Indian Brook Granodiorite 2.53-2.94 2.68 0.07-46.27 14.99 91 Ingonish River Tonalite - 2.80 0.02-55.50 6.14 30 Kathy Road Dioritic Suite 2.43-3.16 2.80 0.04-25.30 3.36 29 Kellys Mountain Gneiss 1.83-3.15 2.81 0.08-12.27 3.47 7 Kellys Mountain Granite 2.33-2.94 2.64 0.06-36.77 3.36 72 Kellys Mountain Diorite 2.53-2.94 2.80 0.12-32.27 8.96 29 McMillan Flowage Formation - 2.81 0.01-25.27 2.10 104 Mount Cameron Syenogranite 2.49-3.533 2.78 0.02-20.41 2.64 15 Shunacadie Pluton 2.47-3.13 2.71 0.02-25.95 4.27 55 Timber Lake Dioritic Suite 2.43-3.16 2.80 0.52-59.67 17.83 4 Wreck Cove Diorite 2.43-3.16 2.80 0.05-54.50 10.37 60 Aspy terrane Black Brook Granitic Suite 2.33-2.94 2.64 0.01-16.20 0.35 167 Cameron Brook Granodiorite 2.53-2.94 2.68 0.02-36.93 3.48 29 Cape North Group 1.83-3.15 2.81 0.05-28.00 3.58 69 Cheticamp Lake Gneiss 1.83-3.15 2.81 0.01-33.30 1.41 43 Clyburn Brook Formation 2.12-3.10 2.73 0.01-10.61 0.95 14 Glasgow Brook Granodiorite 2.53-2.94 2.68 0.02-0.27 0.15 12 Ingonish Island Rhyolite 1.36-2.74 2.50 0.04-40.77 8.36 9 Margaree Pluton - 2.64 0.01-22.60 2.90 34 Money Point Group 2.12-3.10 2.73 0.01-63.13 1.61 116 Neils Harbour Gneiss 1.83-3.15 2.81 0.11-16.00 0.56 34 201
Density Magnetic Susceptibility (g/cm3) (x10-3 SI units) Range Avg Range Avg n Sarach Brook MS - 2.77 0.01-49.53 2.73 66 Wilkie Sugar Loaf Granite 2.33-2.94 2.64 0.01-5.65 0.72 25 Blair River Inlier Anorthosite, Syenite 2.44-2.86 2.72 0.01-50.57 6.00 49 Gneissic Rocks 1.83-3.15 2.81 0.01-47.43 12.51 38 Lowland Cove Formation - 2.64 0.04-132.67 0.18 1
SOUTHWESTERN NEWFOUNDLAND Bay du Nord Group - 2.68 - 2.51 7 Burgeo Intrusive Suite - 2.64 - 18.35 26 Carboniferous Sediments - 2.55 - ~0 - Indian Head Inlier - 2.68 - 2.24 - Steel Mountain Anorthosite - 2.83 - 2.24 - Dunnage Ophiolites - 2.74 - 30.91 36
*Measured susceptibility data from Cape Breton Island are from Appendix A. Measured density data from Cape Breton Island are from King (2002). Other density data are from Tenzer et al. (2011) for similar rock types. Newfoundland data are from Miller et al. (1990).