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Volcanic framework and geochemical evolution of the Archean Hope Bay Greenstone Belt, Nunavut, Canada Shannon, Andrew J. 2008

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VOLCANIC FRAMEWORK AND GEOCHEMICAL EVOLUTION OF THE ARCHEAN HOPE BAY GREENSTONE BELT, NUNAVUT, CANADA  by ANDREW J. SHANNON B.Sc.Hon. University of Waterloo, 2005  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Geological Sciences)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2008  © Andrew J. Shannon, 2008  Abstract Part of the Slave Structural Province, the Hope Bay Greenstone Belt is a 82 km long north-striking sequence of supracrustal rocks dominated by mafic volcanic rocks with lesser felsic volcanic and sedimentary rocks. Mapping of two transects in the southern section and two transects in the northern section have contributed to a robust stratigraphic framework the belt. Three recently discovered Archean lode gold deposits in the Hope Bay Greenstone belt have associations with major structures and specific lithologies (FeTi enriched basalts). The Flake Lake and the Clover Transects are in the southern part of the belt and the Wolverine and Doris-Discovery Transects are in the northern part of the belt. This work subdivides the volcanic rocks into distinct suites based upon field, petrologic, geochemical, and geochronologic criteria. Some of the suites are stratigraphically continuous and can be correlated tens of kilometres along strike thereby linking the two parts of the Hope Bay Greenstone Belt. U-Pb geochronology supports work by Hebel (1999) concluded that virtually all the supracrustal rocks in the Hope Bay Greenstone Belt were deposited over at least 53 m.y. (2716-2663 Ma), with the majority of the volcanism occurring after 2700 Ma. A number of basalt groups are identified and include the normal basalt, the LREEenriched basalt, the Ti-enriched basalt and the Ti-enriched Al-depleted basalt groups. They have chemical signatures that vary in trace elements particularly HFSE and REE’s, and can be easily be distinguished by geochemical screening. The felsic volcanic suites are also divided into three main groups, tholeiitic rhyolite, calc-alkaline dacite and calcalkaline rhyolite groups. Nd and Hf isotope signatures are consistent with trace element  ii  signatures in identifying mafic and felsic volcanic groups, with the tholeiitic rhyolite showing highly variable signature. The Hope Bay Greenstone Belt has been show to have a number of felsic and volcanic cycles. An early construction phase of the belt is made up of primarily mafic volcanics which is followed by felsic volcanism equalled mafic volcanism which lacks basalts enriched in Ti. The geodynamic environment that created the Hope Bay Greenstone Belt can be explained by plume influenced subduction zone.  iii  TABLE OF CONTENTS Abstract ............................................................................................................................... ii Table of Contents .............................................................................................................. iii List of Tables .................................................................................................................... vii List of Figures .................................................................................................................. viii Acknowledgments.............................................................................................................. xi CHAPTER 1 Introduction 1.1 Objective of Thesis ....................................................................................................... 2 1.2 Location, Physiography and Access ............................................................................. 2 1.3 Methods and Sources of Data ....................................................................................... 3 1.4 Geology of the Slave Structural Province and Bathurst Block..................................... 5 1.4.1 The Bathurst Block ............................................................................................ 9 1.5 General Geology of the Hope Bay Greenstone Belt................................................... 10 1.5.1 Mafic Volcanic Rocks...................................................................................... 11 1.5.2 Felsic Volcanic Rocks...................................................................................... 12 1.5.3 Sedimentary Rocks .......................................................................................... 12 1.5.4 Plutonic Rocks ................................................................................................. 14 1.5.5 Metamorphism and Deformation..................................................................... 16 1.5.6 Gold Deposits................................................................................................... 17 Chapter 2 Volcanic architecture and stratigraphic framework of The Hope Bay Greenstone Belt 2.1 Introduction................................................................................................................. 30 2.2 Descriptions of Geologic Transects ............................................................................ 30 2.2.1 Flake Lake Transect................................................................................................. 30 2.2.1.1 Flake Lake Felsic Suite............................................................................. 31 2.2.1.2 Bend Basalt Suite...................................................................................... 32 2.2.1.3 Eastern Granites ........................................................................................ 33 2.2.1.4 Windy Lake Felsic Suite........................................................................... 33 2.2.1.5 Spyder Arm Basalt Suite........................................................................... 34 2.2.1.6 Member Basalt Suite................................................................................. 35 2.2.1.7 Feldspar Megacrystic Gabbro ................................................................... 36 2.2.1.8 Structural Geology .................................................................................... 36 2.1.2 Clover Lake Transect............................................................................................... 37 2.2.2.1 Koignuk Felsic Suite................................................................................. 38 2.2.2.2 West Clover Basalt Suite .......................................................................... 39 2.2.2.3 Clover East Basalt Suite............................................................................ 39 2.2.2.4 Clover Valley Sedimentary Suite.............................................................. 40 2.2.2.5 Clover Lake Felsic Suite........................................................................... 41 2.2.2.6 Belt Margin Granitoid............................................................................... 41  iv  2.2.2.7  Structural Geology .................................................................................... 42  2.2.3 Boston Area Transect............................................................................................... 42 2.2.3.1 Boston Basalt Suite ................................................................................... 43 2.2.3.2 Boston Sedimentary Suite......................................................................... 44 2.2.3.3 Structural Geology .................................................................................... 44 2.2.4 Wolverine Transect.................................................................................................. 45 2.2.4.1 Wolverine Basalt Suite ............................................................................. 46 2.2.4.2 2690 Ma Dacite Unit................................................................................. 46 2.2.4.3 Kennet Tarn Basalt Suite .......................................................................... 46 2.2.4.4 Windy Lake Felsic Suite........................................................................... 47 2.2.4.5 Koig Basalt Suite ...................................................................................... 47 2.2.4.6 Koignuk Felsic Suite................................................................................. 47 2.2.4.7 Structural Geology .................................................................................... 48 2.2.5 Doris-Discovery Transect ........................................................................................ 48 2.2.5.1 Doris Basalt Suite ..................................................................................... 49 2.2.5.2 Mesa Basalt Suite...................................................................................... 50 2.2.5.3 Patch Basalt Suite ..................................................................................... 51 2.2.5.4 Windy Basalt Suite ................................................................................... 52 2.2.5.5 Windy Lake Felsic Suite........................................................................... 52 2.2.5.6 Glen Lake Sedimentary Suite ................................................................... 53 2.2.5.7 Discovery Basalt Suite.............................................................................. 53 2.2.5.8 Koignuk Felsic Suite................................................................................. 54 2.2.5.9 Conglomerate Hill Sedimentary Suite ...................................................... 54 2.2.5.10 Late Mafic Intrusives ................................................................................ 55 2.2.5.11 Structural Geology .................................................................................... 56 2.3 Discussion ................................................................................................................... 57 2.3.1 Correlating and Understanding Transects................................................................ 57 2.3.2 The Belt as a Whole and Comparison to Other Greenstone Belts........................... 60 2.4 Summary ..................................................................................................................... 62 CHAPTER 3 Geochemical Evolution of the Hope Bay Greenstone Belt 3.1 Introduction and Methodology ................................................................................... 89 3.2 Lithogeochemistry ...................................................................................................... 90 3.2.1 Analytical Methods.......................................................................................... 90 3.2.2 General Chemical Classification...................................................................... 91 3.2.3 Mafic Volcanic Rocks...................................................................................... 92 3.2.3.1 Normal Basalt Group ................................................................................ 93 3.2.3.2 Light Rare Earth (LREE) Enriched Basalt Group .................................... 93 3.2.3.3 Ti-enriched Basalt Group.......................................................................... 94 3.2.3.4 Ti-enriched Al-depleted Basalt Group...................................................... 95  v  3.2.4 Felsic Volcanic Rocks...................................................................................... 96 3.2.4.1 Flake Lake Suite ....................................................................................... 96 3.2.4.2 ca. 2690 Ma Dacite ................................................................................... 97 3.2.4.3 Windy Lake Suite ..................................................................................... 98 3.2.4.4 Koignuk Suite ........................................................................................... 99 3.2.4.5 Clover Lake Suite ..................................................................................... 99 3.2.4.6 Clover epiclastics .................................................................................... 100 3.2.5 Chemostratigraphic Columns......................................................................... 100 3.3 Isotope and High Resolution Trace element Geochemistry (PCIGR) ...................... 103 3.3.1 Results of Lu-Hf and Sm-Nd Geochemistry.................................................. 103 3.3.1.1 Model Ages............................................................................................. 105 3.3.2 Alteration and Isotopic Disequilibrium ......................................................... 108 3.3.3 Isotopic Sources of the Hope Bay Greenstone Belt....................................... 109 3.4 Discussion ................................................................................................................. 112 3.4.1 Mafic Volcanic Rocks.................................................................................... 112 3.4.2 Felsic Volcanic Rocks.................................................................................... 114 3.4.3 Correlating Geochemistry within the Hope Bay Greenstone Belt................. 115 3.4.4 Comparisons to other Greenstone Belts......................................................... 116 3.5 Summary ................................................................................................................... 116 CHAPTER 4 Conclusions and Suggestions for Further Work 4.1 Conclusion .................................................................................................................152 4.2 Further work...............................................................................................................153 Bibliography ....................................................................................................................156 Appendices Appendix A: Geochronology Methods and Sample Description ..................................165 Appendix B: Procedures of Geochemical-isotopic Analysis PCIGR............................171 Appendix C: Major and Trace Element Abundances of Samples from the Hope Bay Greenstone Belt, (ALS CHEMEX) ..................................................178 Appendix D: High Resolution Trace Element Abundances of Samples From the Hope Bay Greenstone Belt, (PCIGR) ................................................190 Appendix E: Results and Discussion of QA/QC ..........................................................195  vi  List of Tables 1.1  Summary of rock suites in the Hope Bay Greenstone Belt ...................................20  1.2  Summary of granitic rocks surrounding the Hope Bay Greenstone Belt...............21  1.3  Summary of granitic rocks surrounding the Hope Bay Greenstone Belt...............21  2.1  Zircon U-Pb TIMS analytical data.........................................................................65  2.2  Summary of published U/Pb geochronology.........................................................67  3.1  Average element and inter-element ratio of the mafic rocks in the Hope Bay Greenstone Belt ............................................................................................119  3.2  Average element and inter-element ratio of the felsic volcanic rocks in the Hope Bay Greenstone Belt.............................................................................120  3.3  Hf and Nd isotopic compositions of rocks from the Hope Bay Greenstone Belt....................................................................................................121  vii  List of Figures 1.1  Location map of the Hope Bay Greenstone Belt ...................................................22  1.2  Bedrock geology map of the Slave Structural Province (SSP) and compilation of Northeast Part of the Slave Structural Province ............................23  1.3  Generalized stratigraphic column for the Central and Western SSP .....................24  1.4  General geology of the Hope Bay Greenstone Belt...............................................25  1.5  U/Pb ages of felsic volcanic and sedimentary rock suites .....................................26  1.6  Generalized stratigraphic columns for the Hope Bay Greenstone Belt .................27  1.7  Geologic map of Archean granitoid rocks surrounding the Hope Bay Greenstone Belt......................................................................................................28  2.1  Outline of geologic transects .................................................................................68  2.2  Geologic map of the Flake Transect .....................................................................69  2.3  Structural-stratigraphic column of the Flake Transect ..........................................70  2.4  Field photographs from Flake Transect .................................................................71  2.5  Geologic map of the Clover Transect ...................................................................72  2.6  Structural-stratigraphic column of the Clover Transect ........................................73  2.7  Field photographs from Clover Transect ...............................................................74  2.8  Geologic map of the Boston Area .........................................................................75  2.9  Structural-stratigraphic column of the Boston Area .............................................76  2.10  Field photographs from Boston and Doris Transects ............................................77  2.11  Geologic map of the Wolverine Transect .............................................................78  2.12  Structural-stratigraphic column of the Wolverine Transect ..................................79  2.13  Geologic map of the Doris-Discovery Transect ...................................................80  2.14  Structural-stratigraphic column of the Doris-Discovery Transect.........................81  2.15  Structural-stratigraphic column of the Doris-Discovery Transect.........................82  2.16  Field photographs from Doris Transect .................................................................83  2.17  U/Pb concordia diagrams from volcanic and sedimentary rocks of the Hope Bay Greenstone belt .....................................................................................84  2.18  Locations of U/Pb geochronology samples ...........................................................85  2.19  Stratigraphic reconstruction comparing the north and south parts of the Hope Bay Greenstone Belt.....................................................................................87  3.1  Alkali vs SiO2 plot and SiO2 vs Zr/TiO2 plots of volcanic rocks from the Hope Bay Greenstone Belt...................................................................................124  viii  3.2  Histogram of SiO2 contents and Zr vs Y plot tholeiitic vs calc alkaline MacLean and Barret (1993) .................................................................................125  3.3  Al3O2 vs TiO2 plot and Modified AFM diagram from the Hope Bay Greenstone Belt....................................................................................................126  3.4  Binary plots of major oxides for mafic volcanic rocks from the Hope Bay Greenstone Belt ...........................................................................................127  3.5  Flow diagram describing filtering of geochemical data ......................................128  3.6  Histogram of TiO2 and compilation of REE diagrams for mafic volcanic rocks from the Hope Bay Greenstone Belt ..........................................................129  3.7  Binary plots of trace elements v TiO2 for mafic volcanic rocks from the Hope Bay Greenstone Belt ..................................................................................130  3.8  REE diagrams of four basalt groups ....................................................................131  3.9  Tectonic discrimination diagrams........................................................................132  3.10  Tectonic discrimination diagram .........................................................................133  3.11  Binary plots of felsic volcanic rocks from the Hope Bay Greenstone Belt .........134  3.12  REE diagram felsic volcanic suites in the Hope Bay Greenstone Belt................135  3.13  Binary element ratio diagrams of felsic rocks from the Hope Bay Greenstone Belt....................................................................................................136  3.14  Chemo-stratigraphic reconstruction of the south part of the Hope Bay Greenstone Belt....................................................................................................137  3.15  Chemo-stratigraphic reconstruction of the north part of the Hope Bay Greenstone Belt....................................................................................................138  3.16  143  Nd/144Nd vs 147Sm/144Nd plot ..........................................................................139  3.17  176  Hf/177Hf vs 176Lu/177Hf plot ..........................................................................140  3.18  (143Nd/144Nd)@2.68Ga vs (176Hf/177Hf)@2.68Ga plot ..................................................140  3.19  İNd(i) vs Al2O3/TiO2 plot.......................................................................................141  3.20  İHf(i)vs Al2O3/TiO2................................................................................................141  3.21  General diagram of Sm-Nd model ages...............................................................142  3.22  (143Nd/144Nd)@2.68Ga vs NdIJCHUR ............................................................................143  3.23  Nd  3.24  (  3.25  Nd  (  3.27  Hf  (  Nd/144Nd)@2.68Ga vs NdIJDM ..............................................................................144  IJDM histogram....................................................................................................144  176  3.26 3.28  IJCHUR histogram.................................................................................................143  143  Hf/177Hf)@2.68Ga vs HfIJCHUR .............................................................................145  IJCHUR histogram .................................................................................................145  176  Hf/177Hf)@2.68Ga vs HfIJDM plot .........................................................................146  ix  3.29  Hf  3.30  İNd(i) vs İHf(i) plot ..................................................................................................147  3.31  K/Al vs Na/Al molar ratio diagram .....................................................................148  3.32  İHf(i) vs LOI plot ...................................................................................................148  3.33  143  3.34  İHf(i) vs Al2O3/TiO2 plot........................................................................................150  3.35  İNd(i) vs İHf(i) plot ...................................................................................................147  IJDM histogram....................................................................................................146  Nd/144Nd)@2.68Ga vs (176Hf/177Hf)@2.68Ga ...........................................................149  x  Acknowledgments  In the past two years several organizations and numerous people have supported me in various ways and without them this project would not have been possible. Generous financial support was provided by Miramar Hope Bay Limited, National Science and Engineering (NSERC) and Society of Economic Geology (SEG). My two seasons of field work in Nunavut would not have been possible with out the logistical support provided by Miramar Hope Bay Limited. I would like to thank the faculty at the Department of Earth and Ocean Science at UBC for always having door open and helpful comments. I would particularly like to thank James Scoates, Greg Dipple and Ken Hickey for their time they spent with chatting about geology and answering questions. My committee members of Jim Mortensen, Dominique Weis and Dick Tosdal were instrumental in guiding my goals in this thesis. In the field many people who work for Miramar Hope Bay Limited were instrumental assisting me in work and developing my geologic understand of the Hope Bay Greenstone Belt, particularly Mike, Richard, Blair, Elli, and Darren. I greatly appreciate the contribution of Ross Sherlock. His guidance and assistance has kept me on track and fostered growth as a field geologist. To my supervisor Richard (Dick) Tosdal, thank you for getting me through. You have taught me a great deal about putting together a good academic document and your feedback and time are greatly appreciated. I would like to thank my family and friends who have supported me so many ways through my work. I would like to thank Ashley and Sarah for their time reading drafts and giving feedback.  xi  CHAPTER 1 Introduction  1  CHAPTER 1 1.1 Objective of Thesis Despite over ten years geologic study of the Archean Hope Bay Greenstone Belt, no synthesis paper or mapping based study has been conducted encompassing the entire greenstone belt. Building upon previous detailed geological work and geochronology, this study provides constraints on the evolution of the Hope Bay Greenstone Belt with regards to petrogenesis and tectonic setting of the volcanic successions that host gold deposits. Occurrences of gold in the belt are hosted in, or spatially related to, particular lithologic suites. Geological mapping along with volcanic stratigraphy was integrated with lithogeochemistry, radiogenic isotopes, and geochronology to place the main lithologic suites of the belt into a temporal framework. Using these tools, identified gold deposits can be placed in a regional context which will reduce exploration risk by focusing exploration on stratigraphically favorable rock suites.  1.2 Location, Physiography and Access The Hope Bay Greenstone Belt is located in the Nunavut Territory, which was created on April 1, 1999, as the largest and newest of the Canadian territories. The Hope Bay Greenstone Belt, informally referred to as “the belt”, is situated 750 km northeast of Yellowknife and 150 km southwest of the community of Cambridge Bay (Figure 1.1). Roughly rectangular in shape, the belt is approximately 16 km wide and 82 km long and borders on Melville Sound, which is part of the Arctic Ocean (Figure 1.1). Located 140 km above the Arctic Circle, this greenstone belt is situated in the tundra biome where the soil is permanently frozen in the subsurface. Trees do not grow but  2  vegetation such as berries, lichens, Arctic Willows, moss, grass, and small willow shrubs survive. Supracrustal rocks of the belt make up north trending ridges with the valleys filled with till overlain by marine clays. Surrounding the belt are granitoids which are resistive to weathering processes and form plateaus with close to 100% outcrop. The southern half of the belt has subdued topography with the north-trending ridges usually only representing ten’s of meters of relief. Linear ridges in the northern half of the belt typically have greater relief, although rarely more than 100 m, with the highest point in the study area being approximately 150 m above sea level. Access to the Hope Bay Greenstone Belt is by air and water. In the summer, bulk supplies are shipped by barge to Roberts Bay, from the Great Slave Lake along the Mackenzie River and along the coast (Figure 1.1). Personnel and other supplies are flown from Cambridge Bay or Yellowknife to all weather landing strips, lakes in the summer months or an ice runway in the winter.  1.3 Methods and Sources of Data Field mapping is the foundation of this study and is complimented by geochronology, lithogeochemistry, and isotope geochemistry. In addition to collecting original data, a thorough review of existing documentation was conducted. Field mapping of six geologic transects is the foundation of this study. Transects were mapped at a scale of 1:10,000. Individual transect lengths range from 3 to 10 km long and an average width of several hundred meters. Each transect was selected to include the suites that occur between east granites and west granites and collectively  3  encompass virtually the entire stratigraphy in the Hope Bay Greenstone Belt. These transects are described in Chapter 2, where variations in volcanic textures, distribution of the suites, contact relationships and structural geology are presented along with the overall stratigraphic framework. U-Pb geochronology on intermediate and felsic rocks provide age constraints on the mapped units. The high precision of this method as well as the robust nature and high blocking temperatures (~ 900qC) of zircon crystals make it ideal for dating Archean felsic rocks (Lee et al., 1997). Six samples were collected from surface outcrops during the course of fieldwork and analyzed by the Pacific Centre for Isotopic and Geochemical Research at the University of British Columbia. Results of new geochronology complement by published U-Pb ages (Bevier and Gebert 1991; Hebel, 1999; Sherlock, 2001) are integrated with field relationships in Chapter 2 of this thesis. Major and trace element chemistry was conducted on a set of surface samples collected during the mapping of the six transects. Major element concentrations were determined by X-Ray florescence (XRF) and trace element concentrations were determined by Induced Coupled Plasma - Mass Spectrometry (ICP-MS). Detailed descriptions of analytical methods, presentation of data and interpretation can be found in Chapter 3 and Appendix B. Sm-Nd and Lu-Hf isotopic systems aid in understanding of the variation in the volcanic regime though time. Isotopic analyses were conducted on pulps from rock samples previously collected and analyzed by ALS Chemex. The Sm-Nd system has been extensively used in greenstone belts as isotopic tracers while the relatively newly established Lu-Hf technique has been previously used to a lesser extent on Archean  4  rocks. Sm-Nd and Lu-Hf systems are considered to be relatively immobile and suitable for petrogenetic studies despite the low grade metamorphism and hydrothermal alteration in the study area (Ayer et al., 2002). Analytical methods and procedures as well as presentation of data and interpretation are presented in Chapter 3.  1.4 Geology of the Slave Structural Province The Slave Structural Province (SSP) is located in the northwest portion of the Canadian Shield. This Archean craton, with an area of ~210,000 km2, is comprised of ~50% granitoid rocks, ~35% metasedimentary, ~10% gneissic rocks, and ~5% metavolcanic rocks, with a geologic history that spans ~4500 to 2590 Ma (Figure 1.2) (Padgham and Fyson, 1992; King and Helmstaedt, 1997; Stubley, 2005). The SSP is bounded to the east by the Paleoproterozoic Thelon Orogen (2.02-1.91 Ga) and to the west by the Wopmay Orogen (1.95-1.84 Ga ) (Hoffman, 1988). Early work, by Henderson (1970), on the supracrustal rocks of the SSP subdivided as part of the Yellowknife Supergroup. Supracrustal units both older and younger than the Yellowknife Supergroup have since been identified and are referred to as pre- and post- Yellowknife Supergroup (Kusky, 1989; Isachsen and Bowring, 1994; Bleeker, 1999). Utilizing U/Pb geochronology and newly identified field relationships, a number of authors (e.g., Kusky, 1989; Padgham and Fyson, 1992; Isachsen and Bowring, 1994; Bleeker, 2006) have re-examined the Yellowknife Supergroup and produced a revised stratigraphy of the SSP. This stratigraphy should be applied with caution to the Hope Bay Greenstone Belt as it was based on a greenstone belt from the western Slave.  5  These greenstone belts are many hundreds of kilometres away but are the best studied in the SSP (Figure 1.3). The oldest identified portions of the SSP (4.03 to 2.86 Ga) are found on the west side of the craton. This crystalline basement, known as the Central Slave Basement Complex, has previously been known as the Anton and Sleepy Dragon Terrane (Kusky, 1989; Bleeker, 1999). Based on geochronological and isotopic evidence, the Central Slave Basement Complex is inferred to underlie the central and western portion of the SSP (Bleeker, 1999). The Central Slave Basement Complex consists of polymetamorphic gneisses and, most commonly, heterogeneous dioritic to tonalitic gneisses with some migmatites, that yield protolith ages of up to 4.03 Ga (Stern and Bleeker, 1998; Bowring and Williams, 1999; Bleeker, 1999). In the eastern part of the SSP, much work has been done to understand the relationship between the Central Slave Basement Complex and the supracrustal rocks of the Yellowknife Supergroup. This work may have only limited applicability to the eastern half of the SSP, and the Hope Bay Greenstone Belt. Based on Pb and Nd isotopic compositions there is differing basement rock in the western and eastern parts the SSP (Thorpe et al., 1992; Davis and Hegner, 1992). The 207Pb/204Pb signatures from the eastern Slave are lower (more juvenile) than those found in the west, which suggests that the source in the west is an older, more evolved crust. Other researchers suggest that based on geologic evidence there is little difference between the eastern and western parts of the SSP (Padgham and Fyson, 1992; Padgham, 1995). The Central Slave Basement Complex is overlain by a discontinuous veneer of the autochthonous sedimentary rocks named the Slave Cover Group (2.9 to 2.8 Ga).  6  Preserved in a number of localities, this group is dominated by quartzite and banded iron formation (BIF) with lesser pebble conglomerates (Helmstaedt and Padgham, 1986; Kusky, 1990). These deposits are distributed within the vicinity of the Central Slave Basement Complex and represent remnants of a continental shelf assemblage (Ketchum et al., 2004). A thin cover succession marks the onset of the Neoarchean cycle of supracrustal development in the SSP (Bleeker et al., 1999a). Greenstone belts of the SSP are separated into two broad categories: the Yellowknife-type and the Hackett River-type (Padgham, 1985). Yellowknife-type belts, which are mostly found in the western Slave, are characterized by a thick succession of massive to pillowed tholeiitic basalt flows that may also be interleaved with calc-alkaline felsic volcanic and volcaniclastic rocks. These greenstone belts are seen throughout the western Slave and occur between 2734 and 2697 Ma (Isachsen and Bowring, 1997; Mortensen et al., 1988). There are also minor amounts of sandstone, shale, conglomerates, carbonate units and intra-volcanic sedimentary rocks. The Elu and Hope Bay Greenstone Belt s are the only Yellowknife-type belts found in the eastern SSP. Hackett River-type greenstone belts are characterized by intermediate to felsic calcalkaline volcaniclastic rocks. These arc-like rocks are somewhat younger (post 2700 Ma) and are found mainly in eastern side of the SSP (Mortensen et al., 1988). In the Yellowknife area sedimentation of the Burwash Formation buried some of the volcanic successions (Figure 1.3). This sedimentary sequence is common across the SSP where they form a relatively unmetamorphosed and deformed package of rocks and are considered one of the best preserved Archean deep marine succession in the world (Ferguson et al., 2005). The Burwash Formation around Yellowknife, where it’s type  7  section if found, consists of metamorphosed sandstones and shale with thin felsic tuff layers (Bleeker, 2004). The thinly bedded sandstone-shale units of the Burwash Formation display Bouma sequences, as well as thicker (2-10 m), bedded units (Ferguson et al. 2005). The main phase of sedimentation in the south part of the SSP occurred from 2680 to 2660 Ma, however, in the north part of the SSP, older ages of 2695 and 2671 Ma in High Lake are encountered (Henderson et al., 1994). These ages suggest an older onset of turbidite sedimentation in the far north of the province (Bleeker, 2004). In the SSP, the Burwash-equivalent sedimentary rocks have been given different formational names depending on location; they include the Contwoyto Formation, the Itchen Formation, and the Beechey Lake Group (King and Helmstaedt, 1997; Bleeker, 2006). The youngest sedimentary rocks in the SSP are identified in a number of greenstone belts, the Jackson Lake Formation in the Yellowknife belt, the String Lake conglomerate in the Anialik belt, and the Beauliue River Formation in the Beaulieu belt (King and Helmstaedt, 1997). These late orogenic sedimentary rocks are mainly composed of polymictic conglomerates, cross-bedded sandstones, and some argillite deposited in an alluvial fan sequence (Henderson, 1985; Martel and Lin, 2006). The Jackson Lake Formation (JLF) has been dated at 2605 ± 6 Ma. Similar evidence suggests that the String Lake conglomerate was deposited ca. 2.6 Ga (Isachsen and Bowring, 1994; King and Helmstaedt, 1997). In the Yellowknife Greenstone Belt, these late orogenic sedimentary rocks are found over a length of 37 km some 60 m.y. after the end of widespread volcanism. At a craton scale, the oldest deformation event, D1, is attributed to the closing of the Burwash Basin at ~2650 Ma (Bleeker, 2006). A LITHOPROBE seismic survey of  8  the western SSP has shown a northeast-southwest structural grain (D1) in the lithospheric mantle (Davis et al., 2003). The second deformation event (D2) commenced ca. 2600 Ma, and manifests itself as broadly north-south structural trends (Bleeker, 2006). The onset of D2 also saw the over-thickening of the crust, which led to the generation of S-type granites (Kusky, 1989; Bleeker, 2004). The late felsic intrusives can be grouped into 2620–2605 Ma tonalite to granodiorite plutons followed by ca. 2600–2580 Ma, syn- to late kinematic granites, including two-mica leucogranites, and extensive pegmatites (Villeneuve et al., 1997; Davis and Bleeker, 1999). Granite plutonism at this time shows no regional changes through time and no regional zonation across the SSP (van Breemen et al., 1992; Davis and Bleeker, 1999). After a Proterozoic collisional event with the Rae Province to form the Thelon orogen and creation of the accretionary Wopmay orogen, the Slave Province was accreted to the larger Precambrian Shield of North America (Hoffman, 1989). Two mafic magmatic events affect the SSP in the Early Proterozoic: the intrusion of dike swarms, and minor intrusive complexes. At 2.03 Ga, a swarm of diabase dikes with a variety of orientations were intruded into the central and southern areas of the SSP. At 1.27 Ga, the Mackenzie dike swarm intruded the entire SSP, whereas the Franklin magmatic event at ~ 720 Ma affected only the northern areas (LeCheminant and Heaman, 1989). Kimberlitic magmatism in the Slave occurred during the Cambrian (~ 535 Ma) and the Cretaceous to Tertiary (~ 150 Ma to 40 Ma) (Heaman et al., 2003). 1.4.1 The Bathurst Block At the northeast corner of the SSP is a terrain named the Bathurst Block (Figure 1.2). Separating the Bathurst Block from the rest of the SSP is the northwest striking Bathurst  9  Fault. The Bathurst Fault is not well exposed and for the most part is covered by Proterozoic sediments of the Kilohigok Basin (Fraser, 1964). The rocks that make up the Bathurst Block are similar to those that make up the rest of the SSP and include granitoids, sedimentary rocks and supracrustal rocks forming linear north trending belts. There is little know about the basement in the Bathurst Block but Bleeker (2006) interprets it a being similar to the basement of eastern SSP which is younger than the Central Slave Basement Complex.  1.5 General Geology of the Hope Bay Greenstone Belt The Hope Bay Greenstone Belt is in the north-central part of the Bathurst block. Striking approximately north-south, the Hope Bay Greenstone Belt is dominated by mafic volcanic rocks with lesser felsic volcanic and sedimentary rocks (Figure 1.4), making it analogous to a Yellowknife-type greenstone belt (Padgham, 1985). The metamorphic grade in the Hope Bay Greenstone Belt is mainly greenschist facies increasing to amphibolite facies along the belt margins near the granitoid contacts. For the purposes of this discussion the prefix of meta will be excluded from descriptions of lithologies as the protolith is commonly evident. Available U-Pb geochronology provides a broad temporal framework of the belt which will be complimented by additional geochronology (Figure 1.5). Ages of all the previous geochronology is found on Table 1.1 and the spatial distribution ages determined on felsic volcanic and sedimentary rock suites is found on Figure 2.18.  10  1.5.1 Mafic Volcanic Rocks Submarine mafic volcanic rocks intruded by gabbro dominate the Hope Bay Greenstone Belt. The mafic flows have a wide range of preserved primary textures, including pillowed flows, pillow breccias, hyaloclastite, varioles, amygdules, peperitic textures, gas cavities and pillow selvage (hyaloclastic pillow rims). It is not uncommon to observe massive sections grading into pillowed flows capped by hyaloclastite and breccia (Therriault, 2006). The mafic volcanic rocks suites can be separated based on physical characteristics, geographic location or stratigraphic position and chemical composition. Chapter 2 discusses the physical characteristics and geographicstratigraphic position of the mafic volcanic suites, and Chapter 3 presents the geochemical characterisation of the mafic volcanic units. Mafic volcanic rocks can not be directly dated, but a relative age can be inferred by their relative stratigraphic position with respect to felsic intervals which have been dated. Hebel (1999) assigned all mafic volcanism to the Hayden Formation which is older than 2.7 Ga (Figure 1.6). Within this formation, he identified three distinct mafic suites based on geochemistry called the BG-1, BG-2 and BG-3 which correspond to the Normal, LREE, and Ti-enriched basalts of this study. Gebert (1999) suggests that there are two episodes of mafic volcanism; the first is that described above by Hebel (1999), and the second is a minor suite of basalts at approximately 2660 Ma. In the MadridWolverine corridor, Sherlock et al. (2003) identified a group of Fe-Ti -rich tholeiitic basalts, the Doris Group, as the oldest mafic volcanic rocks in the north part of the Hope Bay Greenstone Belt. These are overlain by a succession of normal basalts (Wolverine Group and Windy Basalts) and Ti-enriched mafic rocks (Patch Group). Few true  11  ultramafic volcanic rocks are observed in the Hope Bay Greenstone Belt; where present the ultramafic volcanic rocks may contain harrisite also known as "Rhum harrisite" texture which is a randomly oriented spinifex (Donaldson, 1982; Lindsay, 1998; Therriault, 2006).  1.5.2 Felsic Volcanic Rocks Five episodes of felsic magmatism are recognized in the Hope Bay Greenstone Belt between 2716 Ma to 2665 Ma (Figure 1.5) (Hebel, 1999). In order of decreasing age they are named the Flake Lake, Square Lake, Windy Lake, Koignuk, and Clover Lake suites. Primary volcanic textures in the felsic rocks permit identification of the coherent, volcaniclastic or epiclastic facies. The Flake Lake Suite (2716 Ma; Hebel, 1999), Square Lake Suite (2690 Ma; Hebel, 1999) and Clover Lake Suite (2662 Ma; Hebel, 1999) are geographically restricted suites. Whereas the Windy Lake Felsic Suite (2686 Ma; Hebel, 1999) and Koignuk Felsic Suite (2677 Ma; Hebel, 1999) are regionally extensive units that can be mapped almost the entire length of the Hope Bay Greenstone Belt. These regionally extensive suites vary in thickness between several hundred meters to over a kilometer.  1.5.3 Sedimentary Rocks Sedimentary rocks in the Hope Bay Greenstone Belt are interbedded with the volcanic rocks and also form thick packages that are interpreted to have been deposited in post- or intra- volcanic sedimentary basins. Sedimentary rocks which are intercalated with volcanic rocks include thinly bedded wacke, argillite and rarely carbonate  12  rhythmites and iron formation. They are found through the mafic and felsic stratigraphy as relatively thin beds or units on a scale of tens of meters. They are usually recessively weathering, so less is known about their distribution (Gebert, 1993; Therriault, 2006). The thicker packages of sediments which are interpreted to have been deposited in post- or intra- volcanic sedimentary basins are noted in a number of localities including the Clover Lake, Spyder Lake, the Windy Lake, Conglomerate Hill and Discovery. These sedimentary rocks consist of greywacke to shale as well as conglomerate. Detrital zircon U-Pb ages indicate a maximum depositional age of 2675 Ma (Hebel, 1999) some of the sedimentary rocks. Some very old zircons (2804 Ma and 3281 Ma) are identified in one sample; however, no rocks of that age have been identified in eastern SSP (Hebel, 1999). Two late- to post- volcanic sedimentary successions containing conglomerate , the Hope Bay Sedimentary Suite and the Conglomerate Hill Sedimentary Suite, are found in the northern part of the belt (Hebel, 1999; Gebert, 1999). The Hope Bay Sedimentary Suite is a polymictic conglomerate with up to 30% rounded granitoid boulders exposed on an island north of Discovery Bay with a maximum depositional age of 2647 Ma (Hebel, 1999), based on detrital zircons from sandy beds in the conglomerate. This formation has been compared by Gebert (1999) and Hebel (1999) to the postYellowknife Supergroup conglomerates of the Jackson Lake Formation of the Yellowknife Greenstone Belt and the Timiskaming sedimentary rocks of the Abitibi Greenstone Belt. However as the outcrop is isolated on an island in the ocean its geologic context is unknown and the relationship to the rest of the belt is uncertain. The Conglomerate Sedimentary Hill Suite is located south of the Hope Bay Sedimentary Suite  13  lacks granitoid boulders and contains a smaller variety of clast types. Gebert, 1999) suggests the conglomerate may have formed from the erosion of the upper felsic volcanic rocks of the Hope Bay Greenstone Belt shortly after the end of volcanism.  1.5.4 Plutonic Rocks Felsic plutonic rocks surround the Hope Bay Greenstone Belt and can be separated into a granitoid series based on field relationships, plutonic textures and geochronology. The first comprehensive study of the granitoids surrounding the Hope Bay Greenstone Belt was conducted by Thompson (1996, 1997) who divided the granitoids into three main groups (Figure 1.7) (Table 1.2). Sherlock and Sandeman (2004b) revised the suites (Table 1.3). Thompson (1996, 1997) outlined Group I as metagranitoids, migmatites and a gneisses complex dated at 2650 +2.9/-2.5 Ma (Hebel, 1999). This high-grade metamorphic suite lies along the southeastern part of the Hope Bay Greenstone Belt where it is in contact with low metamorphic grade supracrustal rocks that cross a zone of ductile deformation (Thompson, 1997). A titanite U-Pb age of 2589 Ma (Hebel, 1999) is thought to represent cooling from the peak metamorphism for this suite. Thompson (1997) interprets the Group I rocks to be much older than the lower greenschist facies rocks that they are in contact with, and favors an unconformity. This idea conflicts with geochronology results mentioned above, which suggests a syn-metamorphic fault. Sherlock and Sandeman (2004b) name this suite of rocks Group II (Table 1.3). This is based on the observations that the rocks comprising Group I, outline by Thompson (1997, 1998), are not as metamorphosed as previously thought and is likely a  14  syn- to late-D2 intrusion. The gneissosity is believed to have developed by a biotitic schleiren and amphibolite- inclusion charged granodioritic magma that was intruded by widespread veins and sheets of monzogranite that were subsequently flattened. Thompson (1996, 1997) outlined Group II intrusives as a syn-volcanic suite that is situated to the east of the Hope Bay Greenstone Belt, where they have been dated at 2672 +3/-1 Ma (Bevier and Gebert, 1991). A variety of rock types compose this group including a mafic metaplutonic suite and a metatonalite suite. These rocks may extend eastward as far as the Elu Greenstone Belt (Figure 1.7). The Group II rocks intruded prior to the main phase of metamorphism and deformation, and are interpreted to be the plutonic components of the magmatic event that produced the volcanic rocks of the Hope Bay Greenstone Belt. The volume of syn-volcanic granitoids is inferred to be much larger than that reported from anywhere else in the Slave Province (Thompson, 1997). Sherlock and Sandeman (2004b) has renamed this granitoid suite Group I based on the observation in the metagranitoid suite as well as the geochronology. Thompson (1996, 1997) outlined Group III granitoids, which lie along the west side of the belt, as an undeformed or unmetamorphosed suite (Figure 1.7). Group III rocks dated at 2608±5 Ma (Bevier and Gebert 1991) include a monzodiorite suite, a biotite tonalite suite, and a biotite granite suite (Thompson, 1997). Thompson (1997) suggests that Group III granitoids intruded after the volcanic rocks and older granitoids following significant deformation and metamorphism, but before regional deformation ceased. The observation by Thompson (1997) and geochronologic constrains are consistent with the observations elsewhere in the SSP (van Breemen et al., 1992).  15  Proterozoic magmatic events that have affected the Hope Bay Greenstone Belt include the ca. 2000 Ma Beechey dikes, the 1267 Ma Mackenzie dikes, and the 723 Ma Franklin Diabase (Gebert, 1993).  1.5.5 Metamorphism and Deformation Low-metamorphic grades dominate the Hope Bay Greenstone Belt, except for the margins of the belt where the rocks are metamorphosed to amphibolite facies. Metamorphic mineral assemblages of hornblende + plagioclase ± garnet characterize the rocks along the belt margin, whereas chlorite+ albite + epidote + quartz + actinolite characterize the rocks in the interior of the belt. Timing of regional metamorphism is partially constrained by the granites to the west, dated at 2609 Ma (Bevier and Gebert, 1991), which are unaffected by metamorphism (Thompson, 1997). A titanite U-Pb age of 2589 Ma from metagranitoid (Group I, Thompson (1997), Group II, Sherlock and Sandeman (2004b)) is interpreted to date cooling after a peak of regional metamorphism (Hebel, 1999). Contact metamorphism is observed as centimeter to meter wide aureoles of hornfels around syn-volcanic and post-volcanic dikes. Locally penetrative cleavages cut the deformed rocks of the Hope Bay Greenstone Belt. The oldest deformation event is poorly constrained, but is marked by a foliation (S1) that is subparallel to the dominant foliation (S2) (Gebert, 1999). A second cleavage, S2, is the most strongly developed fabric in the belt. It generally strikes between 030° and 330° and is steeply dipping. The D2 deformation produced folding (F2) as a result of east-west shortening and S2 is the north-trending axial planar cleavage to these folds The Doris anticline can be  16  traced for ten's of kilometers is a prominent F2 fold pattern in the north part of the belt (Sherlock and Carpenter, 2003). All the earlier fabrics are affected by a third deformation event (D3) which locally forms complex fold interference patterns. The F3 folds are observed south of Flake Lake in the River Bend area. The north-south shortening during D3 may also account for doubly plunging geometry of the Doris anticline (Gebert, 1999).  1.5.6 Gold Deposits The Hope Bay Greenstone Belt contains three gold deposits and numerous prospects. Th gold deposits (Doris, Madrid, Boston) (Figure 1.4) and showings are hosted mainly in the mafic volcanic rock and, to a lesser extent, in sedimentary and plutonic rocks. The Doris and Madrid deposits are located in the north part of the belt whereas the Boston is located in the south part of the belt (Figure 1.4). Currently being permitted for mining, the Doris deposits resource contains a total of ~1.5 Million oz Au. Deposits in the Madrid area have resources of ~ 7.8 Million oz Au whereas the Boston deposit contains a ~1.5 Million oz Au resource (Miramar, 2007). Minor base metal occurrences are and Au-rich syn-volcanic alteration assemblages are associated with felsic volcanic units (Gebert, 1999; Sherlock and Lindsay, 2002). The Doris deposit, in the north part of the Hope Bay Greenstone Belt, occurs as a quartz-carbonate vein system traceable for 3 km (Carpenter et al., 2003). The deposit is hosted by amygdaloidal pillowed basalt succession with minor gabbro. The contact between the Fe-Ti rick basalts (hangingwall) and a gabbro (footwall) is the host to the quartz carbonate veins. Basalt and gabbro of the deposit have been folded into a tight,  17  doubly plunging, north-striking anticline (Carpenter et al., 2003). Two of the mineralized veins, known as the Central and Lakeshore veins, contain slivers of tourmaline-ankeritepyrite altered wall rock, this wall rock typically host the ore (pyrrhotite, pyrite, and gold). The strongest sericite-dolomite/ankerite-quartz ±tourmaline ±rutile ±hematite ±pyrite ±gold alteration is at the vein selvage. Distal hydrothermal alteration is characterized by quartz-chlorite-calcite-albite ± actinolite-tremolite ±epidote ±magnetite ±rutile.  Pyrite  is ubiquitous throughout the altered wall rock and increases in concentration proximal to the vein (Sterritt, 2003). Located in the northern part of the Hope Bay Greenstone Belt between Windy and Patch Lake, are the Madrid group of deposits (Naartok, Rand, Suluk and South Suluk) (Figure 1.4). Gold is occurs in quartz-ankerite-sericite-albite-pyrite volcanic rocks cut by complex network of quartz stockwork veins (Sherlock 2003; Therriault 2006; Madsen et al., 2007). Volcanic stratigraphy in the Madrid area includes mafic volcanic flows, gabbros, argillitic sedimentary rocks and feldspar porphyric rocks (Sherlock et al., 2003; Therriault, 2006, Madsen et al., 2007).  The deposits lies in the hanging wall of a  regional structure called the Deformation Zone (DEFZ) is an important feature controlling gold occurrences with lenses along the hanging wall contact and as pods within it, but no gold has been recognized in the footwall of the DEFZ (Madsen et al., 2007). Gold is present in carbonatized, albiteized and silicified breccia zones with quartz stockwork veins and disseminated pyrite (Madsen et al., 2007). The deposits are hosted in altered mafic volcanic flows and flow breccias characterized by intense albitization, brecciation, and iron-carbonate flooding (Therriault, 2006). The most intense alteration  18  is characterized by carbonate minerals (ankerite, magnesite or ferroan dolomite), quartz, chlorite, rutile, sericite, albite, hematite, and pyrite (Sterritt, 2003; Therriault, 2006). Gold is typically in carbonate located at the quartz vein margins, where it is often associated with pyrite and trace chalcopyrite (Therriault, 2006). The large alterations system in the Madrid area gives way to typical greenschist mineral assemblages on the periphery, including hornblende, actinolite, chlorite, albite, calcite, quartz, epidote, and titanite (Sterritt, 2003). The Boston deposit, southernmost in the belt, is a mafic volcanic-hosted, multistage, mesothermal quartz-ankerite-sulphide vein system (Stemler, 2000; Stemler et al., 2006). The host mafic volcanic rocks and interflow sedimentary rocks are deformed in a tightly folded anticline with sub vertical lithologic contacts. Proximal alteration destroyed the primary volcanic textures, and is characterized by quartz, ankerite, sericite, paragonite and pyrite (Sherlock and Sandeman, 2004a). Gold is hosted in pillowed basalt flows, volcaniclastic rocks and sedimentary rocks and is controlled by anastomozing axial planar shear zones (Sherlock and Sandeman, 2004a). Vein formation was accompanied by widespread wall rock alteration in the form of carbonitization, hydrolysis, hydration, and sulfidation (Stemler, 2000). In a fluid inclusion study Stemler et al. (2006) shows that auriferous fluid responsible for mineralization at Boston were similar to those in other greenstone belts, (low salinity (4.6 ± 1.4 eq. wt.% NaCl) H2OCO2 trapped at 320ºC and pressures 2 to 3 kbar).  19  Table 1.1: Summary of rock suites in the Hope Bay Greenstone Gebert (1993, 1999), Bevier and Gebert (1991), Hebel (1999), Carpenter et al. (2003), Sherlock et al. (2003), Sherlock and Sandeman (2004), Therriault (2006)  U/Pb age (Ma)  2ı Error (Ma)  -  -  Patch High Ti-Fe Basalts  -  -  Doris High Ti-Fe Basalts  -  -  Normal Tholities  -  -  Boston High Ti Basalts  -  -  -  -  Flake Lake suite  2716  +3.1 -2.6  Square Lake suite  avg 2690  n/a  Wolverine suite  2689.4  +4.0 -3.6  Windy Lake suite  avg 2685  n/a  Koignuk suite  avg 2677  n/a  Clover Lake suite  2663  +3.4 -2.8  max 2675  ±3.0  Conglomerat Hill Sedimentry max 2670 Suite  ±2.5  Hope Bay Sedimentry Suite max 2647  ±2.8  Rock Type and Suite Name Ultramafic Volcanic Rocks Patch komatiitic basalts  Distribution  Referance  meter scale flows around Madrid Therriault 2006  Mafic Volcanic Rocks ~150m wide striking north with a Sherlock et al. 2003 length of ~10km ~100m wide striking north Carpenter et al. 2003 exposed at surface 1km belt wide distribution Hebel 1999, Gebert 1999 Sherlock and Sandeman found within the Boston Anticline 2004  Intermediate Volcanic Rocks Son Voit Suite  Found at the south central end of Hebel 1999 the belt  Felsic Volcanic Rocks restricted to the south central east restricted to the central west portion of the belt restricted to the area around Madrid belt wide destribution along the center of the belt belt wide destribution at the west margin of the belt restricted to two outcrops 3km northwest of Boston  Hebel 1999 Hebel 1999 Sherlock unpublished data 2001, Sherlock et al. 2003 Hebel 1999, Sherlock et al. 2003 Bevier and Gebert 1991, Hebel 1999, Hebel 1999, Sherlock and Sandeman 2004  Sedementry Rocks Wilko Sedimentry Suite  belt wide destribution along the Hebel 1999 center of the belt confined to the north half of the belt in the center of the belt confined an island to the north of Hebel 1999 the belt  20  Table 1.2: Summary of Granitic rocks surrounding the Hope Bay Greenstone Belt (after Thompson 1997) U/Pb Age Field observation Group I  2650Ma  Group II 2672Ma  pre-volcanic?  syn-volcanic  Subgroup  Description  Mafic metaplutonic suite  foliated, recrystallized granite to tonalite, granitic to tonalitic granitoid migmatite, quartzofeldspathic gneiss, tonalite, granitic to tonalitic granitoid migmatite, quartzofeldspathic gneiss, mettagabbro biotite/hornblende diorite, tonalite to quartz diorite, leucogabbro, gabbro, anorthosite; massive to moderately foliated, variably recrystallized  Metatonalite suite  biotite/hornblende tonalite, some granodiorite; intensely foliated and recrystallized  Metagranitoidmigmatite-gneiss complex  hornblende/biotite tonalite, minor granodiorite; massive to  Pitted metatonalite suite moderately foliated, variably recrystallized; differential weathering of coarse-grained biotite forms pits  Group III 2608Ma  post-volcanic, syn-D2  Monzodiorite suite  biotite-hornblende quartz monzodiorite, monzodiorite, granodiorite, diorite; typically foliated and recrystallized with lenticular inclusions of metavolcanic rocks near contact with greenstone belt  Biotite tonalite suite  granodiorite to tonalite; schistose to gneissic metasedimentary and metavolcanic inclusions which define a foliation.  Biotite granite suite  biotite granite to granodiorite, K-feldspar megacrysts typical; weakly foliated locally; 8a - relatively fine-grained, inclusions of granitoid migmatite, quartzofeldspathic gneiss, foliated metatonalite, mafic metavolcanic rocks, and/or metagabbro  Table 1.3: Summary of Granitic rocks surrounding the Hope Bay Greenstone Belt (after Sherlock and Sandeman 2004b) U/Pb Age Field observation  Description  syn-volcanic  fine- to medium-grained biotite-magnetite-bearing granodiorite to monzogranite  Group II 2650Ma  post-volcanic, syn-D2  medium- to coarse-grained biotite-titanite ± hornblende ± epidote-bearing tonalite  Group III 2608Ma  post-D2  leucocratic, medium-grained, microcline porphyritic, biotite ± magnetite ± hornblende-bearing granodiorite to monzogranite  Group I  2672Ma  21  Beaufort Sea Victoria Island Baffin Island CAMBRIDGE BAY  KUGULKTUK Melv  Great Bear Lake  ille S  ound  HOPE BAY  GJOA HAVEN ic Arct  le Circ  NWT  r  ive eR nzi  cke  Ma  5 ~7  0K  M  NUNAVUT  YELLOWKNIFE RANKIN INLET  Great Slave Lake  BC  Hudson Bay  ALBERTA SASK.  Figure 1.1: Location map of the Hope Bay Greenstone Belt (modified Miramar Figure)  22  a  Proterozoic platformal cover and orogenic belts  Other greenstone belts, mostly younger than 2.73 Ga  2.73-2.70 Ga tholeiitic greenstone belts  2.68-2.63 metaturbidite sequences  2.68-2.58 Ga granitoids; including migmitites, gneisses. Locally includes pre-2.8 Ga granitoids and gneisses.  Known and inferred basement gneisses  Bathurst Block  H.B.  t ul Fa t s  Phanerozoic cover  W op m  Can ad U.S,A a .  n  a y Or og e  Paleozoic cover  67°00'  68°00'  106°00'  67°00'  pink gneiss migmatite granitoid  tonalite  metagraywacke knotted schist sillimanite schist gneiss sillimanite migmatite granite  (south of 67°)  68°00'  Labyrinth Bay  EIVB  LEGEND  Elu Inlet  Hope Bay Greenstone Belt  Melville Sound  Kent Peninsula  Dease Strait  108°00'  20 0 20 After Gebert 1993  km  Bathurst Inlet  Umingmaktok  metavolcanic rocks  granite, granodiorite  gneiss, migmatite  Proterozoic cover  Diabase  106°00'  Figure 1.2 a: Bedrock geology map of the Slave Structural Province (SSP) with inset map of Canada with SSP craton shaded, Hope Bay Greenstone Belt labeled; H.B.: after Hoffman & Hall 1993; Bleeker 1999; Stubley 2005 b: Geologic compilation of northeast part of the Slave Structural Province Bathurst Block north of latitude 67 from Fraser (1964), south of latitude 67 after Thompson et al. (1986), figure modified after Gebert (1993)  b 108°00'  Ellice River Terrane  (north of 67°)  Fr? ont The lon  LEGEND  rs thu Ba  Ce  Archean & Paleoproterozic rocks of the Canadian Shield Slave Structural Province (SSP)  ke Sla ntr al  x ple om  23 B a s em ent C  T H E L (C ON T h u rch ECTON Thelon Fro ill P nt ? rov IC ZON ince E )  1000 km  th ur  Bathurst T errane  Ba u Bath nlet r st I ne Zo ult a tF  CSBC  YELLOWKNIFE SUPERGROUP  Locally developed late-tectonic conglomerates (ca.2.60-2.58 Ga) Unconformity  Burwash Formation turbiditic graywacke-mudstones (2.67-2.65 Ga)  felsic and intermediate volcanic rocks, volcaniclastic, basalts (2.69-2.66 Ga)  Disconformity/unconformity Thin rhyolite tuff intercalations (2.72-2.70 Ga) pillowed and massive tholeiitic basalts (2.73-2.70 Ga) Central Slave Cover Group Quartzite, ultramafic sills, iron formation Unconformity Central Slave Basement Complex (4.04-2.83 Ga)  Figure 1.3: Generalized stratigraphic column for the Central and Western SSP (modified Henderson 1970; Bleeker et al. 1999; Bleeker et al. 2001)  24  Figure 1.4: General geology of the Hope Bay Greenstone Belt with selected lakes, D.L.: Doris Lake, W.L.: Windy Lake, SQ.L.: Square Lake, G.L. Gascache Lake, F.L.: Flake Lake, S.L.: Spyder Lake, C.L.: Clover Lake Doris  Legend D.L.  Archean Rocks  W.L.  Late Sedimentary Rocks Madrid  Late Granites  P.L.  Late Mafic Intrusive Rocks Early Sedimentary Rocks Early Granites (Synvolcanic) Synvolcanic Mafic Intrusive Rocks Mafic to Intermediate Volcanic Rocks Felsic Volcanic Suites Unassigned Felsic rock  SQ.L.  Clover Lake Suite  G.L.  Koignuk Suite Windy Lake Suite Square Lake Suite  F.L.  Flake Lake Suite  S.L. C.L.  Boston  0  25  5  10  20 Kilometers  26  Age (Ma)  Volcanic and hypabyssal  Flake Lake Felsic Suite  Wolverine Lake Felsic Suite  Square Lake Felsic Suite  Windy Lake Felsic Suite  Koignuk River Felsic Suite  Clover Lake Felsic Suite  Diorite  Wilco Sedimentary Suite  Conglomerate Hill Sedimentary Suite  Clast in Hope Bay Sedimentary Suite  Hope Bay Sedimentary Suite  Group III Granitoids  Group II & I Granitoids  Sedimentary  Hebel 1999  Sample  Plutonic  Padgham 1996  Bevier and Gebert 1991  This Study  Figure 1.5 U/Pb ages of felsic and sedimentary suites (after Bevier and Gebert 1991; Padgham 1996; Hebel 1999; Sherlock 2001; Sherlock 2001 (unpublished data) , Shannon 2008 (this study):  2730  2720  2710  2700  2690  2680  2670  2660  2650  2640  2630  2620  2610  2600  Sherlock 2001  27  a) Farrar Group Tweedy Group Westerberg Group Young Group  Hayden Basalt Suite (>2716 Ma)  Flake Lake Felsic Suite (2716 Ma)  Son Volt Suite (unknown age)  Square Lake Felsic Suite (2690 Ma)  Wolverine Lake Felsic Suite (2686 Ma)  Windy Lake Felsic Suite (2685 Ma)  Koignuk River Felsic Suite (2677 Ma)  Clover Lake Felsic Suite Wilco (2663 Ma) Sedimentary Suite  Hope Bay Sedimentry Suite (<2647 Ma)  Dacite volcanic conglomerate non-variolitc Mg tholeiitic pillowed basalt  Koignuk Felsic Suite  Dacite coherent flows/sills  Fe tholeiitic pillow basalts  ~1 km  Variolitc Normal tholeiitic pillowed basalt  re a k  non-variolitc Normal tholeiitic pillowed basalt  Wolverine porphyry, feeder to Windy Lake felsics  non-variolitc Mg tholeiitic pillowed basalt  dacite volcaniclastic intervals  Windy Lake Felsic Suite, grading into more proximal facies northward  b)  id B Madr  Figure 1.6: a) Generalized stratigraphic column for the Hope Bay Greenstone Belt with original stratigraphic nomenclature of formations replaced by suites (after Hebel 1999; Gebert 1999) b) stratigraphic column for the Patch Doris corridor with (after Sherlock et al. 2003; Therriault 2006)  Yellowknife Supergroup  Group III (syn-D2 granitoids) 7  Biotite tonalite  8  Biotite granite suite  6  Monzodiorite suite  Figure 1.7: Geologic map of Archean granitoid rocks surrounding the Hope Bay Greenstone Belt (Thompson, 1997)  Group II (synvolcanic) 5  Pitted metatonalite  4  Metatonalite suite  3  Mafic metaplutonic suite  Group II metatonalite  Supracrustal rocks 2  8 2653 Ma Soapstone Hill  Arctic Ocean  Metamorphosed Volcanic and Related Rocks  2  Group I 1  Kuugaarjuk Lake  3  2672 Ma  8  Metagranitoidmigmatite-gneiss  HOPE BAY  2  Doris  8  2608 Ma  5  Windy Lake  Group III biotite granite  3  5  Madrid  3  2 4  4  2  8 Group II pitted metatonalite  HOPE BAY VOLCANIC BELT  2 4  1  2  7 3 3  3  2715 to 2663 Ma  unmapped  2  2  8 Group II mafic metaplutonic suite  2 6  4  8  4  4 8  unmapped 4  3  Group III monzodiorite suite  Spyder Lake  2  0  Boston unmapped  1  2649.5 Ma  Km  4 F3  Group I metagranitoid migmatite  2 2 2  28  2 21  5  gneiss  10  15  CHAPTER 2 Volcanic Architecture and Stratigraphic Framework of The Hope Bay Greenstone Belt  29  2.1 Introduction This chapter combines field relationships and U-Pb geochronology from discrete transects across the belt to create a composite stratigraphic framework. Understanding the volcanic architecture of the Hope Bay Greenstone Belt places the gold deposits in a stratigraphic context and reduces risk by focusing exploration efforts.  2.2 Descriptions of Geologic Transects Six geologic transects were mapped across the Hope Bay Greenstone Belt. They were selected to include virtually the entire stratigraphy of the Hope Bay Greenstone Belt (Figure 2.1). Three transects were mapped in the northern and three transects in the southern parts of the belt to illustrate the stratigraphic differences along strike. The stratigraphic and structural relationships of each volcanic suite in each transects is described. A number of assemblages and formations have been previously described by Hebel (1999), which was considered but not necessarily incorporated here as the understanding of the belt scale stratigraphy has evolved since Hebel’s work Instead, rock units sharing similar physical, chemical or geographic characteristics will be referred to informally as suites. The transects in the south part of the belt are presented first and the transects in the north are presented second. Within each transect the suites will be discussed in stratigraphic order, from oldest to youngest.  2.2.1 Flake Lake Transect The Flake Lake Transect covers the area from Flake Lake to the east side of Spyder Lake (Figure 2.1 and 2.2). Rock units in this transect include the Flake Lake Felsic Suite, a feldspar porphyritic gabbro, the Windy Lake Felsic Suite, and at least three  30  mafic volcanic suites. The volcanic stratigraphy of this transect forms two homoclinal successions, with pillows facing to the northeast, that are juxtaposed by a fault. In this transect three mafic volcanic suites were subdivided on textural differences and supported by geochemistry. An inferred fault divides the transects into two domains. The older domain lies to the northeast and contains the Flake Lake Felsic Suite and Bend Basalt Suite, and the younger domain lies to the southwest and contains the Windy Lake Felsic Suite, Spyder Arm Basalt Suite and the Member Basalt Suite (Figure 2.2). Although some suites are intercalated, the following descriptions focus on characterising of the individual suites and their stratigraphic and structural relationships.  2.2.1.1 Flake Lake Felsic Suite The majority of the Flake Lake Felsic Suite is found on the northeast side of Flake Lake, but is also found south of the lake in the ‘River Bend’ area where it is intercalated with the Bend Basalt Suite (Figure 2.2). This suite, on the north shore of Flake Lake, is massive rhyolite with up to 0.5cm in diameter blue quartz phenocrysts making up 20% of the rock. In the same area, rare volcaniclastic textures, including a number of quartz phyric lapilli in a quartz porphyritic matrix, are observed (Figure 2.4a). The Flake Lake Felsic Suite is bounded to the north and east by granites and to the south and west by basalts. It has subsequently been intruded by a large gabbro body on the southeast margin of the suite. Gabbro dikes, related to this intrusion, cross cut the Flake Lake Felsic Suite. The Flake Lake Felsic Suite is also found to the southwest of the large gabbro as a thin strip of rhyolitic volcaniclastic rock and minor sedimentary beds less than 20 cm thickness (Figure 2.2).  31  The Flake Lake Felsic Suite is the oldest felsic suite in this transect, with a volcanic two age dates indicating that felsic volcanism spanned from at least 2716±7.8 Ma (Hebel 1999) to 2697.6±8.9 Ma (AJS 1, Table 2.1 and Figure 2.17). The volcaniclastic sections dated at 2697.6±8.9 Ma are intercalated with the Bend Basalt Suite which shows that part of the Flake Lake Felsic was coeval with mafic volcanism. These ages, along with field relationships, show that the Flake Lake Suite is the oldest suite of felsic volcanic rocks and lie in the lower portion of the stratigraphy of the Flake Lake Transect (Figure 2.3).  2.2.1.2 Bend Basalt Suite Pillow basalts, named the Bend Basalt Suite, stratigraphically underlie and are intercalated with a thin volcaniclastic rock section of Flake Lake Felsic Suite on the southwest side of the feldspar porphyritic gabbro (Figure 2.2). This basalt suite is approximately 1.5 km thick with a consistent northeast facing direction determined from pillow tops. This suite is dominantly composed of moderately well formed pillows with local sections of megapillows (>2.5 m). The pillows commonly have amygdules, as well as small (~0.5mm) plagioclase phenocrysts. Fresh surfaces of these basalts are usually dark green with medium to dark brown weathered surface. Pillow selvages range in size from 15 cm to less than 3 cm (Figure 2.4b). Within the pillowed unit, there is a minor component of medium-grained massive sections, interpreted to be either massive flows or syn-volcanic dikes or sills. A felsic dyke with the same chemical composition as the Flake Lake Suite, intruded the Bent Basalt Suite, suggesting that the Bend Basalt Suite is older than the Flake Lake Suite (Figure 2.3). This porphyritic dike has irregular contacts with the  32  surrounding mafic pillows and has abundant quartz phenocrysts. The regional magnetic data shows a strong lineament at the base of the Bend Basalt Suite, which is interpreted as a fault.  2.2.1.3 Eastern Granites To the east of the supracrustal rocks of the Flake Transect is a suite of felsic intrusives. This suite of intrusive rocks is located along the majority of the east side of the Hope Bay Greenstone Belt and is made up of a medium-grained granodiorite ± biotite. Bevier and Gebert (1991) dated this group of granites at 2672+3/-1 Ma and suggesting a syn-volcanic origin.  2.2.1.4 Windy Lake Felsic Suite Stratigraphically below the Member Basalt Suite is a 100 m interval of dacitic volcaniclastic rocks, dated at 2685±2.0 Ma (AJS 3, Table 2.1 and Figure 2.17). These rocks are considered part of the Windy Lake Felsic Suite and have massive porphyritic and breccia facies (Figure 2.2). The porphyritic section has 40-55%, 1-5 mm feldspar phenocrysts in a grey matrix and is likely a flow or sill. The breccia section has fragments of quartz up to 4 cm, and feldspar porphyritic clasts in a grey matrix. It is separated from the main portion of the Windy Lake Felsic Suite by the Spyder Arm Basalt Suite (Figure 2.3). The base of the stratigraphy of the younger domain of the Flake Lake transect is formed by a thick (750 m) portion of the Windy Lake Felsic Suite that lies against the edge of the north arm of Spyder Lake (Figure 2.2). This suite is characterized by two facies; a primary volcanic facies, and a resedimented syn-eruptive volcaniclastic facies.  33  This terminology used to classify volcanic rocks has been created by such workers as Easton et al. 1989; McPhie et al. 1994. In this area, the volcanic portion of the Windy Lake Felsic Suite is composed of a dark grey porphyritic dacite with 1 to 3 mm quartz phenocrysts. This monotonous portion of the Windy Lake Felsic Suite lacks clasts or bedding, and has been dated at 2685+4/-2 Ma (Bevier and Gebert 1991). The second facies of the Windy Felsic Suite is a volcaniclastic facies, with significant sedimentary textures, found stratigraphically below the primary volcanic facies. At the top of the section that is less than 100 m thick a monomictic conglomerate is interpreted as a resedimented syn-eruptive volcaniclastic deposit (Figure 2.4e). Stratigraphically below the volcanic conglomerate are volcanogenic sedimentary deposits ranging from wacke to siltstones (Figure 2.4f). Sedimentary features, including graded beds, cross beds and flame structures, indicate stratigraphic younging is to the northeast. From the field relationships and U/Pb geochronology, the Windy Lake Suite is the oldest stratigraphic unit in the younger domain of the Flake transect (Figure 2.3).  2.2.1.5 Spyder Arm Basalt Suite The Spyder Arm Basalt Suite, named after the adjacent lake, overlies the majority of Windy Lake Felsic Suite but is locally overlain by a unit of Windy Lake Suite age dacite dated at 2685±2.0 Ma (AJS 3, Table 2.1 and Figure 2.17) (Figure 2.2). This basalt suite differs from the Member Basalts Suite in color and geochemistry; it is much lighter in color on both the fresh and weathered surface, and contains varioles and gas cavities (Figure 2.4d). Locally this basalt suite is light rare earth enriched, discussed further in Chapter 3.1, supporting it’s distinction from the other basalt suites in this transect. This unit is composed almost entirely of pillowed flows with minor massive flows or sills.  34  An isolated discontinuous gabbro intruded along the contact of a 14 m wide felsic unit is intercalated with the Spyder Arm Basalt Suite. This minor felsic volcaniclastic unit has abundant feldspar phenocrysts with small amounts of quartz phenocrysts and many lapilli fragments, as well as local quartz clasts (up to 5 cm). This unit stratigraphically lies within the Windy Lake Felsic Suite indicating that it was deposited at the same time ca. 2685 Ma (Figure 2.3).  2.2.1.6 Member Basalt Suite Southwest of the Bend Basalt Suite is a package of mafic volcanic rocks named the Member Basalt Suite (Figure 2.2). The majority of this 2 km thick suite is pillowed, and locally has subequal proportions of massive and pillowed flows. This suite is ~2 km in thickness and has similar size and shaped pillows as the Bend Basalt Suite unit discussed above. This unit has a green color on the fresh surface and consistently thin (<5cm) pillow selvages. Almost all the pillowed and massive flows lack notable quantity of phenocrysts, amygdules or varioles. A few intervals containing amygdules or very small plagioclase phenocrysts have been observed (Figure 2.4c). This suite of volcanic rocks clearly faces to the northeast as shown by numerous pillow tops as well as gas cavities. Gas cavities also know as pillow shelves are the result of repeated filling and empting of pillow lava tubes (Batiza and White 2000). They are flat bottomed with a top that is concave down and are excellent younging indicators. The absolute age of this unit is not known but from field relationships it stratigraphically overlies the Windy Lake Felsic Suite (2685 Ma) (Figure 2.3).  35  2.2.1.7 Feldspar Megacrystic Gabbro This gabbro pluton and has intruded much of the Flake Lake Suite (Figure 2.2). This gabbro is medium to coarse grained with abundant pink feldspar phenocrysts that range in size from <1 mm to 10 cm. This plutonic body has numerous large (>10 m) roof pendents/ xenoliths as inclusions of rock with mineralogy and textures consistent with Flake Lake Suite. Also observed are rare macroscopic blue quartz crystals. These are likely xenocrysts due to presence of xenoliths as well as composition of this gabbro not allowing it to crystallize quartz. Equivalent gabbro dykes with or without feldspar, are found intruding the stratigraphy throughout the belt. The absolute age of this unit is unknown, but from field relationships, it is one of the youngest intrusions in the Hope Bay Greenstone Belt and has no comparable volcanic suite (Figure 2.3).  2.2.1.8 Structural Geology The earliest fabric (S0) is seen as bedding in sedimentary rocks and can also be approximated by pillow younging feature (pillow tops and gas cavities). The dominant fabric observed in this transect, and the rest of the belt, is a single penetrative foliation, and is termed S2. S2 is fairly consistently trends approximately north-south and steeply dipping. Folding is locally observed in the Member Basalt Suite as well as near inferred or mapped faults. In the Flake Lake Transect S3 is observed as crenulation of S2 and in the area adjacent to the transect F3 is observed as complicated fold interference pattern of lithologic units. The feldspar megacrystic gabbro south of Flake Lake contains a system of close-spaced fractures trending east-north-east and commonly has alteration along  36  their margins. There are no large scale folds identified that affect the rocks in this transect and this is supported by lack of changes in facing direction or foliation. Geochronology supports two homoclinal sequence with the Flake Lake Felsic Suite (2697 Ma and 2716 Ma) juxtaposed below the Windy Lake Felsic Suite (2686 Ma). The fault that juxtaposes the Bend Basalt Suite against the Member Lake Basalts is not directly observed as it lies in a valley but no rotation in the foliation is observed.  2.1.2 Clover Lake Transect The Clover Lake Transect extends west of Spyder Lake to the edge of the granites that form the the west margin of the Hope Bay Greenstone Belt, a length of approximately 6.5 km (Figure 2.1). The transect starts on the shore of Spyder Lake and proceeded west to include the area around Clover Lake and the Koignuk River (Figure 2.5). A wide range of mafic volcanic, felsic volcanic and sedimentary rocks form the transect. Similar to the Flake Lake Suite, there are two different age sequences of rocks separated by a fault. On the west side there is an older domain which is made up of the Koignuk Felsic Suite (2677 Ma) and Clover West Basalt Suite. The east (younger) domain is made up of the Cover East Basalt Suite, Clover Sedimentary Suite and Clover Felsic Suite (2662 Ma). The break between the two domains is mapped as a fault lying at the east side of the Clover West Basalt Suite. This fault juxtaposes the younger Clover Sedimentary Suite rocks against the Clover West Basalt Suite (Figure 2.6).  37  2.2.2.1  Koignuk Felsic Suite  The westernmost felsic volcanic package observed on this transect is the Koignuk Felsic Suite (Figure 2.5). On the regional scale, the Koignuk Felsic Suite appears to be in angular contact with the mafic volcanic rocks to the east . A late fault cuts the east portion of the Koignuk Felsic Suite where diabase dikes are displaced. This suite stratigraphically youngs to the east based on graded beds in the sedimentary rocks at the top of the suite. The strtagraphic base of this suite contains a series of aphanitic to quartz phyric epidote altered felsic flows, flow breccias and tuffs. Stratigraphically above this is the feldspar porphyry, dated at 2677 +2.5/-1.1 Ma (Hebel 1999), is the dominant rock type of the Koignuk Felsic Suite, (~1.2 km thick) and contains few primary features aside from occasional bedding. The rocks are interpreted as crystal tuffs and grade into a volcaniclastic succession dominated by lapilli stone with lesser breccia (Figure 2.7e and f). Stratigraphically above the volcanic rocks is a facies dominated by volcanic-derived sedimentary rocks ranging from immature feldspar and minor quartz phyric tuff to more mature sedimentary rocks, such as argillite, siltstone and wacke. The stratigraphic base of the sedimentary facies is defined by a dolomite unit. This unit is massive dolomite to dolomite rhythmite with a maximum thickness of 20 meters, and grades up stratigraphy to a siltstone (Figure 2.7d). The massive dolomite ranges in thickness, but averages approximately 2 meters. The rhythmite section has centimeter scale bedding that alternates between dolomite and quartz-cemented siltstone. In this dolomite unit numerous graded beds indicate stratigraphic younging is eastwards, which is consistent with the overlying sedimentary rocks. The The Koignuk Felsic Suite is the oldest (2677 Ma) and thickest felsic suite in the Clover Transect (Figure 2.6).  38  2.2.2.2  Clover West Basalt Suite  West of the Clover Valley Sedimentary Suite is a suite of mafic rocks informally named the Clover West Basalt Suite (Figure 2.5). The contact between this package and the Clover Valley sedimentary rocks is interpreted as a ductile fault, although the exact relationship between the two units has not been totally resolved. The Clover West Basalt is composed of well formed, pillowed flows with a significant amount of mafic intrusions and lesser mafic volcaniclastic rocks. Stratigraphically on the top of this suite, the rocks are weakly variolitic. The pillows in the center of the unit lack primary features, whereas the west side has some amygdaloidal sections. Numerous facing reversals in the pillowed flows and repetition of the gabbro and a volcaniclastic rock unit suggest that this unit is tightly folded. The contact relationship between the Clover West Basalt Suite and the Koignuk Felsic Suite to the west is not observed, but new data suggest that it is faulted in places but likely part of the stratigraphy (R. Sherlock, pers comm, 2006). Field relationships and geochronology show that the West Clover Basalt Suite stratigraphically overlies the Koignuk Felsic Suite (2677 Ma) (Figure 2.6).  2.2.2.3  Clover East Basalt Suite  The package of rock directly west of Spyder Lake is dominated by light green, normal and light rare earth enriched pillowed basalt (see Chapter 3). This package lies along the western shore of Spyder Lake, and is named the Clover East Basalt Suite (Figure 2.5). It is a mixture of pillowed, and lesser massive, flows, as well as synvolcanic mafic intrusions. A thin felsic dike intrudes the middle of the suite, and numerous pillow top directions suggest that stratigraphy youngs to the west. The top of  39  this package contains the highest density of varioles seen in this transect and is lighter in color compared to underlying flows. A dacite breccia approximately 25 m thick is interbedded in the upper 100 m of the mafic package. This rock ranges from 10 to 70% clasts in a matrix of altered soft and dark brown material. The feldspar phyric clasts, which range in size from 0.5 to 10 cm, are sub-rounded. The breccia is overlain by a unit of strongly foliated pillows, and variolitic pillows greater than 1 m in diameter. This unit stratigraphically underlies the Clover Valley Sedimentary Suite which has an inferred age of ca. 2663 Ma (Hebel 1999) (Figure 2.6).  2.2.2.4  Clover Valley Sedimentary Suite  To the west of the Clover East Basalt Suite is a package of sedimentary rocks named the Clover Valley Sedimentary Suite as it lies in the Clover Valley (Figure 2.5). A number of facies make up this suite including resedimented syn-eruptive volcaniclastic rocks and sedimentary rocks ranging from conglomerate to argillite. A 25 m thick volcanic sandstone recognized south of Clover Lake forms the stratigraphic base of this suite. This sandstone unit contains a number of porphyritic clasts but is dominated by rounded feldspar grains and few quartz grains (Figure 2.7b). Above the sandstone unit is a heterolithic pebble conglomerate with clasts of sedimentary, volcaniclastic and coherent volcanic rock (Figure 2.7a). Rocks in the upper part of this unit include argillite with lesser greywacke. Graded bedding indicates stratigraphic younging is to the west. Along strike to the north, outside of the transect area, contradictory facing directions are mapped, suggesting structural complexity in that locality (B. Hrabi, pers comm., 2005). There is a great deal of structural complexity but overall the Clover Valley Sedimentary  40  Suite grossly faces to the west and the stratigraphically overlies the Clover East Basalt Suite (Figure 2.6).  2.2.2.5  Clover Lake Felsic Suite  The Clover Lake Felsic Suite lies within the argillite facies of the Clover Sedimentary Suite, and outcrops on the north shore of Clover Lake (Figure 2.5). The Clover Lake Suite has two parts: the first is coherent feldspar porphyry, dated at 2663 +3.4/-2.8 Ma (Hebel 1999); and the second is a breccia unit. The coherent portion of this unit is a massive rhyolite that is quartz and feldspar porphyritic and likely represents a sub-volcanic intrusion or core of a dome. The breccia facies of this felsic suite has angular rhyolite clasts that range in size from 0.5 to 6 cm set in an argillite matrix (Figure 2.7c). These textures are consistent with felsic magma intruding into wet sediments and creating complex lava-sediment breccia called peperite. Sherlock and Sandeman (2004a) suggested these rocks were a carapace breccia. The felsic volcanic rocks are interpreted as having intruded and are intercalated with the Clover Valley Sedimentary Suite (Figure 2.6).  2.2.2.6  Western Granitoid  A felsic intrusive unit is encountered at the west margin of the Koignuk Suite and marks the edge of the greenstone belt (Figure 2.5). This massive, fresh, medium grained tonalite to granodiorite has up to 15% hornblende and has no fabric. These observations are consistent with Group III (post-volcanic) granitoids found on the west side of the belt (Thompson 1997; Sherlock and Sandeman 2004b). The contact between the intrusives and the dacite flows is sharp and has little alteration or deformation along it. This unit  41  has been dated at 2608 ±5 Ma (Bevier and Gebert 1991), which is much younger than volcanism in the belt, and is not represented in the stratigraphic column (Figure 2.6).  2.2.2.7  Structural Geology  The earliest fabric (S0) is seen as bedding in sedimentary rocks and can also be approximated by pillow younging feature (pillow tops and gas cavities). The dominant deformation event D2 is observed as the S2 which trends approximately north. There is transposed bedding in thinly bedded argillite of the Clover Valley sedimentary Suite which is called S3. The folding in the Clover Transect is identified in Clover West Basalt Suite as well as outcrop scale parasitic folding in the Clover Lake Sedimentary Suite. The folding in the Clover West Basalt Suite has a number of north trending fold which are indicated by unit repetition and changes in facing direction, are shallowly plunging. Geochronology of this transect suggests that a fault exists that juxtaposes the older domain (the Koignuk Felsic and Clover West Basalt Suites) against the younger domain (Clover Sedimetry and Clover East Basalt Suites). This fault is located at the west side of the Clover Valley between the Clover Sedimentary Suite and the Clover West Basalts.  2.2.3 Boston Area Transect The Boston area transect lies south of the Boston deposit (Figure 2.1), located on a peninsular near the south end of Spyder Lake between the south arm of Spyder Lake and Stickleback lake (Figure 2.8). The geology of this area is well understood due to its potential economic importance (Clark 1996; Stemler; 2000; Sherlock and Sandeman 2004a, Stemler et al., 2006). Field relationships and extensive drilling have defined an  42  approximately north trending anticline with mafic rocks in the core, overlain by sedimentary rocks (Figure 2.9). The oldest rocks in the area are a suite of normal and Tienriched basalts, which are folded into either a synformal anticline or an overturned anticline (Sherlock and Sandeman 2004a). A succession of normal pillow basalts with locally variolitic pillowed flows are found stratigraphically overlying the other basalts. Mafic volcaniclastic rocks overlain by sedimentary rocks with an age of 2675±2.5 Ma (LMB055, Table 2.1 and Figure 2.17) form the top of the sequence.  2.2.3.1  Boston Basalt Suite  The core of the Boston anticline is composed of green, normal pillowed basalts cross cut by syn-volcanic dikes (Figure 2.8). The rocks found at the north end of the Boston anticline are highly iron carbonate altered and have experienced ductile shearing, despite this some volcanic textures including pillows can be recognized (Figure 2.10a). The mafic volcanic flows are composed of pillows with thin black pillow selvages. Although variable, this unit is approximately 150 m thick. The pillowed basalt unit grades into a section of variolitic pillowed flows. The variolitic pillows are a medium to light green, and have up to 5 cm pillow selvages (Figure 2.10b). Varioles in the pillows are commonly coalesced in the center of the pillow, with some less variolitic pillows having a few varioles occurring around the outer edge of the pillow. Stratigraphically above the variolitic mafic volcanic rocks is a unit of mafic volcaniclastic rocks which is a volcaniclastic clast supported breccia that is usually deformed (Figure 2.9).  43  2.2.3.2  Boston Sedimentary Suite  Stratigraphically above the mafic volcaniclastic rocks is a sedimentary package informally named the Boston Sedimentary Suite. These rocks underlie Spyder lake and are found on the east and west limb of the Boston anticline (Figure 2.8). This package consists of argillite and wacke deposited as turbidites. The rocks that stratigraphically overlie the volcanic rocks in the Boston Area have a maximum depositional age of 2675±2.5 Ma (AJS 6, Table 2.1 and Figure 2.17). The contact between the sediments and the volcanics is not observed on surface; but the reconstructed geometry from diamond drilling indicates the Boston Sedimentary Suite is in parallel with the Boston Basalt Suite (E. Alesi, pers. comm. 2007) (Figure 2.7).  2.2.3.3  Structural Geology  The geology of the Boston Area is dominated by a large scale south plunging fold (Sherlock and Sandeman 2004a). This anticline, which is defined by graded beds and pillowing facings, has a core of the Boston Basalt Suite overlain by the Boston Sedimentary Suite. The deformation in the area is complex, S2 is well developed and trends from northeast to northwest. There is a well developed steeply south plunging stretch lineation. The sedimentary rocks preserve the best record of deformations including S0 (bedding), S1 (transposed bedding), S2. There are at two generations of folds observed F2 and F3 , F3 is acute to F2. The age of the sedimentary rocks on the west limb of the Boston Anticline is 2675.8±2.5 Ma and the rocks on the east limb include the Windy Lake Felsic Suite (2686 Ma) (Figure 2.9). This relationship indicates a disconformity between the sedimentary rocks and the underlying mafic volcanic rocks in the Boston Area.  44  2.2.4 Wolverine Transect The Wolverine transect, in the north part of the Hope Bay Greenstone Belt, starts between Patch Lake and Wolverine Lake (Figure 2.1 and 2.11), and ends at the Koignuk River. A variety of rock units including pillowed mafic volcanic and felsic volcanic suites underlie this transect. The Wolverine transect is underlain by a homoclinal package of volcanic, intrusive and sedimentary rocks. The base of the stratigraphy in this transect is bounded by a north-striking fault, the Hope Bay Deformation Zone. West of the Hope Bay Deformation Zone lies a thick package of pillow basalts called the Wolverine Basalt Suite, which is intercalated with a hetrolithic breccia and dacite tuffs, the tuffs are dated at ca. 2690 Ma. Near the base of this basalt unit is the Wolverine Intrusive dated at 2686 Ma (Sherlock, unpublished data). Stratigraphically above the Wolverine Basalt Suite is a suite called the Kennet Tarn Basalt Suite that is dominantly Ti-enriched basalts. These rocks are overlain by a sedimentary portion of the Windy Lake Felsic Suite. The Windy Lake Felsic Suite is overlain by the Koig Basalt Suite which is the complex mix of normal and Ti-enriched basalts, which is in turn overlain by the Koignuk Felsic Suite (2677 Ma), the youngest rocks in the transect. The package of rocks in this transect are in normal stratigraphic succession, and represent a large part of the stratigraphy in the north part of the belt. U-Pb ages indicate volcanism in this transect occurred between 2690 and 2677 Ma.  45  2.2.4.1  Wolverine Basalt Suite  The Wolverine Basalt Suite is an interval of pillowed basalts which is over 1 kmthick. It has been intruded by the Wolverine Porphyry (2684.2±3.6 Ma), and is intercalated with a number of felsic beds, dated at ca. 2690 Ma, and is bounded to the east by the Hope Bay Deformation Zone. In this transect the Wolverine Basalt Suite consists of well formed pillows with consistent stratigraphic younging to the west with local massive flows preserved. These pillows have weathered to a dark brown color, have thick selvages and lack varioles. This suite also contains massive flows and mafic intrusives.  2.2.4.2  2690 Ma Dacite Unit  The Wolverine Basalt Suite is intercalated with at least two volcaniclastic facies of ca. 2690 Ma age rocks. Two north striking feldspar phyric tuff beds have been dated at 2691.1±2.0 Ma and 2691.7 ±2.5 Ma (AJS 4 and AJS 5, Table 2.1 and Figure 2.17). Stratigraphically below these tuffs is a unit containing a heterolithic breccia and lapilli tuff facies. The lapilli tuff portion has been dated at 2689 +4.0/-3.6 Ma (Sherlock, 2003). These felsic rocks are stratigraphic equivalents as the Square Lake Felsic Suite is found ~20 km to the southwest.  2.2.4.3  Kennet Tarn Basalt Suite  West of the Wolverine Basalt Suite is a sequence of dark green pillowed basalts and massive flows (Figure 2.11) informally named the Kennet Tarn Basalt Suite. This suite contains Ti-enriched basalts which will be discussed further in Chapter 3. Facing  46  directions are not directly found in this poorly outcropping suite but it is inferred to face west based on the enclosing strata (Figure 2.12).  2.2.4.4  Windy Lake Felsic Suite  To the west of the Kennet Tarn Basalt Suite lies a volcanic-derived sedimentary package, correlated with the Windy Lake Felsic Suite, dated ~3 km to the north at 2685 +2.0/-2.5 Ma (Figure 2.11). In this area, the Windy Lake Felsic Suite is made up of the volcanic-derived sedimentary rocks composed of siltstone and wacke. The unit is approximately 250 m thick, and contains well preserved graded beds that face west. The Windy Lake Felsic Suite stratigraphically overlies the Kennet Tarn Basalt Suite (Figure 2.12).  2.2.4.5  Koig Basalt Suite  Stratigraphically above the Windy Lake Felsic Suite are mafic volcanic rocks called the Koig Basalt Suite (Figure 2.11). This unit is made up of large (~1 m), well formed pillow basalts that are locally light rare earth enriched and Ti-enriched (discussed in Chapter 3). This unit has abundant pillow breccia and vesicles, with the east side of the unit containing the majority of pillow breccia textures. Pillow tops face stratigraphically to the west and were deposited on top of Windy Lake Felsic Suite (Figure 2.12).  2.2.4.6  Koignuk Felsic Suite  The Koignuk Felsic Suite, stratigraphically overlies the Koig Basalt Suite, it is the uppermost unit in the Wolverine transect (Figure 2.11). Here, the Koignuk Felsic Suite is composed of a monomictic volcanic breccia which grades upward over a short  47  stratigraphic distance into a lapilli bearing volcaniclastic rock within tens of meters of the base of the unit and then grades into a feldspar porphyritic volcaniclastic rock over the next 100 m (Figure 2.12). The Koignuk fault, which cuts the Koignuk Suite, bounds the western margin of the transect. The Koignuk Suite, dated at 2677.4+1.9/-1.5 Ma (Hebel 1999), is the youngest suite in the Wolverine transect.  2.2.4.7  Structural Geology  The structural geology of this transect is relatively simple; it is a homocline sequence of basalt, dacite and sedimentary rocks laid in stratigraphic order. The tops are consistently to east, determined from graded beds, pillow tops and gas cavities. There are no parasitic folds, changes in facing direction or rotated foliations to suggest large scale folding. The only large scale structural feature of this transect is found at the base which is bounded by the Hope Bay Deformation Zone. In the volcanic derived siltstones of the Windy Lake Felsic Suite the S0/S1 relationship is observed, where S1 is parallel to S0. The dominant fabric observed is the result of D2, it is named S2, it overprint all earlier fabrics and is acute to S1/S0 transposed fabrics 2.2.5 Doris-Discovery Transect The Doris-Discovery Transect extends to the west from the Doris deposit to the shore of Hope Bay (Figure 2.1 and 2.13). This 7 km long doglegged transect is underlain by of a number of intervals of felsic, mafic and sedimentary rocks. Felsic volcanic and sedimentry rocks include the Windy Lake Felsic Suite, Koignuk Felsic Suite and Conglomerate Hill Sedimentary Suite.  48  The Discovery area is highly faulted, and comprises at least three different lithologic units. The Discovery Basalt Suite can be correlated with the Koig Basalt Suite in the Wolverine Transect. The Doris anticline is an extremely large structural feature traceable over 5 km north and south of the transect (Figure 2.13). The stratigraphic lower part of the transect is made up of rocks on the west limb of the anticline, they are a series of basalts that are in stratigraphic succession, from youngest to oldest, the Doris Basalt Suite, Mesa Basalt Suite, variolitic Doris Basalt Suite, Mesa Basalt Suite, Patch Basalt Suite and variolitic Windy Basalt Suite. The top of the Windy Basalt Suite is in stratigraphic contact with the Windy Lake Felsic Suite in one location, whereas in other locations it is separated by an intrusive component of the Windy Lake Felsic Suite (Figure 2.14). The relationship between the Windy Lake Felsic Suite and units in the Discovery Area is not directly observed in this transect, but the stratigraphic relationship to the south can be traced to the Discovery Area. The oldest rocks in the discovery area are part of the sedimentary facies of the Windy Lake Felsic Suite (the Glen Lake Sedimentary Suite), which is structurally overlain by Discovery Basalt Suite, and the Conglomerate Hill Suite. Outside this transect area, to the south, this structural contact are known to be stratigraphic.  2.2.5.1  Doris Basalt Suite  The Doris gold deposit is located at the north end of Doris Lake, and is hosted in the Doris Basalt Suite at the core of a north striking doubly plunging anticline (Figure 2.13). The Doris Basalt Suite is composed of dark green mafic flows made up of pillowed basalts, vesicular pillowed basalt, and massive basalt (Figure 10d). The vesicular  49  pillowed flows are moderate to highly vesicular, with vesicles up to 0.5 cm (Figure 10c). The thickness of these flows range from 10 to 60 m, with the total thickness of the Doris Basalt Suite being 250m. At the core of the anticline, a fine to medium grained massive to pillowed flow (Carpenter et al. 2003). The Doris Basalt Suite has magnetic and nonmagnetic sections that are stratigraphically continuous. Individual flows can be mapped, and the center of each flow is more magnetic than the top and bottom of the flow. This magnetic pattern represents primary petrogenetic controls rather than destruction of magnetite during hydrothermal alteration. These basalts are the oldest volcanic rocks in the northern part of the belt (Figure 2.14). At the top of the Doris Basalt suite is a 200 to 300 m thick unit of highly variolitic dark green pillowed basalt is found. This basalt is similar to the Doris Basalt Suite in pillow size, colour and chemistry. It is characterized by stretched varioles that measure 0.2 to 1 cm in diameter and plunge steeply to the north. It is separated from the non-variolitic vesicular Doris Basalts by a 150 m unit pillows texturally similar to the overlying Mesa Basalt Suite. This intercalation of the Doris Basalt Suite and Mesa Basalt suite suggests that the deposition of these two suites overlapped. 2.2.5.2  Mesa Basalt Suite  Stratigraphically overlying the Doris Basalt Suite is a suite named the Mesa Basalt Suite, after a geographic feature to the north (Figure 2.10 and 2.13). The Mesa Basalt Suite is the largest stratigraphic unit in the Doris-Discovery transect, with an approximate thickness of 1 km. The Mesa Basalt Suite is almost entirely composed of green, well-formed pillows, with minor pillow breccia (Figure 2.10e). Locally, there are sections of megapillows (pillows over 2m in diameter), which are found close to the top  50  of the unit (Figure 2.16d). All pillow tops give a west facing direction and there is no evidence of internal folding of this suite. Minor meter scale sections of massive basalt and pillow breccia form part of the Mesa Basalt Suite. A number of large, up to 30m wide, gabbro dikes with chilled margins intruded the upper parts of the Mesa Mafic Suite.  2.2.5.3  Patch Basalt Suite  To the west of the Mesa Basalt Suite lies a chemically and texturally distinct group of rocks referred to as the Patch Basalt Suite (Figure 2.13). This basalt suite is host to a number of gold deposits further south in the Madrid area. These rocks are susceptible to weathering, and usually lie in valleys under cover and rarely crop out. In the Doris Transect, the majority of this suite is pillowed basalt, with few massive basalt sections. In the Madrid area, along strike and outside the transect, a variety of textures are also present, including peperitic and harrisitic (a pseudo-spinifex texture) textures, as well as a variety of auto breccias (Therriault 2006; Madsen et al., 2007). Pillows in this suite are extremely dark in some cases almost black on the fresh surface (Figure 2.16b). Pillows are round and amoeboid in shape, and are characteristically smaller than the majority of pillowed basalts in the Hope Bay Greenstone Belt (Figure 2. 16a). This rock type is preferentially mineralized compared to the suites of basalts nearby (Windy Basalt and Mesa Basalt Suites) (Madsen et al., 2007). Poor pillow shapes of this unit do not allow direct determination of younging directions, but it is inferred to young westward based on stratigraphic relationships of the enclosing strata (Figure 2.14).  51  2.2.5.4  Windy Basalt Suite  West of the Patch Basalt Suite is a highly variolitic pillowed unit called the Windy Basalt Suite (Figure 2.13). It is dominantly composed of large pillow basalts, approximately 1 m in diameter, which are light green on the fresh surface, with thin and light brown pillow selvages. This group of basalts has abundant gas cavities, and facing directions are consistently west. There are also sections of discontinuous flow breccia as well as fine- to medium-grained massive basalt. Varioles are few at the pillow rim but increase in abundance several centimetres from the pillow rim to form coalesced varioles at the center of the pillow (Figure 2.16c). The unit conformably overlies the Patch Basalt Suite (Figure 2.14).  2.2.5.5  Windy Lake Felsic Suite  To the west of the Windy Basalt Suite is the Windy Lake Felsic Suite (Figure 2.13). This transect lacks the contact between the Windy Basalt Suite and Windy Lake Felsic Suite due to the intrusion of a quartz diorite, but along strike the contact is observed to be stratigraphic . On the Discovery transect, an intrusive portion of the Windy Lake Felsic Suite is observed, and is interpreted as a sub-volcanic portion of this suite (Sherlock et al. 2003). This porphyritic intrusion has a wide range of feldspar and quartz phenocryst content and size (0.01 to 10 mm). Epidote alteration is also common. Quartz ranges from 0 to 20% of the rocks where as, the feldspar laths compose 10 to 45% of the rock. To the west of the intrusion, the volcaniclastic portion of the Windy Lake Felsic Suite is a polymictic breccia with abrupt vertical facies changes (Figure 2.16 e and f). This breccia has clast-poor and clast-rich facies, and has a wide range of matrix compositions, from aphanitic to quartz and feldspar rich. The breccia portion of the  52  Windy Lake Felsic Suite grades rapidly into a massive quartz feldspar porphyritic unit. In some locations, this unit is homogeneous, but elsewhere distinct beds are characterized by changes in grain size and differing phenocryst content (Figure 2.14).  2.2.5.6  Glen Lake Sedimentary Suite  To the west of the Glen Lake is a group of sedimentary rocks called the Glen Lake Sedimentary Suite (Figure 2.13). The Glen Lake Sedimentary Suite is made up of immature siltstones with lesser argillite. Graded beds show facing is to the west and it has a maximum depositional age of 2678.4±2.8 Ma (LMB-55, Table 2.1 and Figure 2.17) based on U-Pb ages of detrital zircon. To the south it can be correlated with sedimentary rocks so this unit is not actually a distinct sedimentary suite but instead it is part of the Windy Lake Felsic Suite. It represents the end of the sedimentation of Windy Lake Felsic Suite and gives an age range on the Windy Lake Felsic Suite.  2.2.5.7  Discovery Basalt Suite  To the west, and overlying the Windy Lake Suite is a package of mafic volcanic rocks refered to as the Discovery Basalt Suite (Figure 2.13). This unit is made up of pillowed mafic volcanic rocks and almost an equal volume of gabbro intrusions. Pervasive wide spread iron carbonate alteration is found in the Discovery area, as well as at least two well-developed, subparallel foliations, which obscure primary volcanic textures. Nonetheless, relic pillow shapes are locally observed in the Discovery Basalt Suite, but no facing indicators can be found. To the south, outside the transect area, good pillows face to the west in the Koig Basalt Suite and these facing directions can be correlated to the Discovery Basalt Suite. There is faulting in this area which forms north  53  trending ridges and ~100 m wide valleys. The majority of these brittle-ductile faults are north-striking, but other perpendicular (west-striking) brittle faults are observed. The displacement on the north-striking faults is not known but the west-striking faults have tens of meters of offset. Due to this faulting, the primary contact relationships of the Discovery Basalt Suite and enclosing strata must be inferred from areas along strike where they can be observed (Figure 2.15).  2.2.5.8  Koignuk Felsic Suite  Stratigraphically overlying the Discovery Basalt Suite is a portion of felsic volcanic rocks that can be correlated south to the Koignuk Felsic Suite (2677 Ma). In this area these rocks exhibit volcano-sedimentary textures; the bottom of the unit is primarily a crystal tuff with some sections of lapilli tuff. Subangular plagioclase and quartz crystals, with few lithic fragments in a dark grey siliceous matrix characterize the rock. Westward, the unit lacks plagioclase, and clasts become round, suggesting a change from a resedimented syn-eruptive volcaniclastic deposit to a volcanogenic sedimentary deposit.  2.2.5.9  Conglomerate Hill Sedimentary Suite  Stratigraphically above the Koignuk Felsic Suite lies a package sedimentary rocks called the Conglomerate Hill Sedimentary Suite (Figure 2.13). The east side of this suite has portions of the Koignuk Felsic Suite intercalated with argillite of the Conglomerat Hill Sedimentary Suite. Further west and up stratigraphy, the tuffaceous rock of the Koignuk Felsic Suite disappears and the unit consists of thinly bedded argillites with some sandstone beds high in the sequence (Figure 2.15). Above the argillites are conglomerate, with 5 to 65 cm beds of a polymictic pebble conglomerate interbedded  54  with graded course sandstone beds. Clasts in the conglomerate are felsic volcanic rocks, argillite to arenaceous sedimentary rocks, and few mafic volcanic rocks (Figure 2.16g). Round to sub-angular clasts have a maximum size of 30cm, but an average size of <10 cm. Bedding strikes approximately north and dips moderately to the west. Graded, course sandstone beds show that the unit is upright, and stratigraphically youngs to the west. One of these sandy beds has been dated by U-Pb methods and gives a maximum depositional age of 2670.6±2.5 Ma (LMB-56, Table 2.1 and Figure 2.17). The contact between the Conglomerate Hill Sedimentary Suite and the Discovery Basalt Suite is difficult to discern as it has been faulted on most localities. Along strike the contact is believed to be stratigraphic . In the Discovery area it is interpreted that the sedimentary rock suites stratigraphically overlie the Discovery Basalt Suite (Figure 2.15).  2.2.5.10  Late Mafic Intrusives  In the Discovery Area, the Conglomerate Hill Sedimentary Suite is intruded by northstriking diorite intrusions (Figure 2.13). These intrusions form thick sills that run approximately parallel to bedding, trending north. The xenolith-rich diorite is characterized by abundant hornblende and lesser plagioclase phenocrysts in an aphanitic matrix. Xenoliths are made up of rounded, equigranular granitoids material, mostly monzogranites but rare xenoliths of volcanic and sedimentary rocks are also noted. The xenolith size ranges from <5 cm to ~45 cm, with the average xenolith clast being ~20 cm in diameter. There is minimal wallrock alteration with the surrounding sedimentary rocks.  55  2.2.5.11  Structural Geology  The Doris Discovery transect encompasses the entire west limb of the Doris anticline, which is the largest structural feature in the northern part of the belt. This anticline fold hinge trends north under Doris Lake and is shallowly doubly plunging (Sherlock et al. 2003). The anticline is mapped based upon facing direction in the normal pillow basalts; The earliest deformation event D1 is observed in the sedimentary rocks of this transect, it is name S1 and is transposed bedding S0. The dominant penetrative fabric in the Doris-Discovery transect is S2 which strikes north-north-east and is steeply dipping. S2 is the result of east west compression which also formed the doris anticline and it is at an acute angle to S1. This transect has some excellent examples of stretched varioles in the Doris Basalt Suite,. These stretching lineations are consistently north-north-west and steeply dipping. There is little evidence in this transect for D3 but subtle larger scale F3 patterns have been identified (Sherlock et al. 2003). The Discovery Area consists of a number of fault blocks. These fault blocks include a number of homoclinal sequences. Found furthest to the east is a mixture of relatively fresh gabbro and iron carbonate altered basalts of the Discovery Basalt Suite. The fault block to the east contains a sequence from dacite pyroclastic and resedimented syn-eruptive volcaniclastic rocks of the Koignuk Felsic Suite, and argillites and conglomerates of the Conglomerate Hill Sedimentary Suite which appears to contain some F2 folding, from parasitic folding along lithologic contacts. The most westerly fault block is composed of the Conglomerate Hill Sedimentary Suite with bedding upright and dipping moderately west which is intruded by the Late Mafic Intrusives.  56  2.3 Discussion Mapping of the Hope Bay Greenstone Belt along six transects shows the belt to be composed of at least six felsic volcanic suites, thirteen mafic volcanic suites and three sedimentary rock suites. Geochronology data from this study supports work by Hebel (1999) which concluded that virtually all the supracrustal rocks in the Hope Bay Greenstone Belt were deposited over at least 53 m.y. (2716-2663 Ma). Felsic volcanism has been shown to occur episodically, commonly punctuating periods of mafic volcanism that may have occurred relatively consistently throughout the construction of the Hope Bay Greenstone Belt.  2.3.1 Correlating and Understanding Transects The oldest felsic suite in the Hope Bay Greenstone Belt is the Flake Lake Felsic Suite, and now has two U/Pb dates of 2716±7.8 Ma (Hebel 1999) and 2697.6±8.9 Ma (AJS 1, Table 2.1 and Figure 2.17). The Flake Lake Felsic Suite is spatially restricted to the area in the south part of the belt around Flake Lake. Two samples from this suite that were processed for U/Pb geochronology indicate a 19 m.y. (2716 -2697 Ma) age range for the Flake Lake Felsic Suite, which is a large age range for a magmatic event. When the errors are included the age range may be as short as 7 m.y. which could be considered a reasonable range for a single magmatic event. The age range of the Flake Lake Suite most likely explained by a single magmatic event with several stages of magma generation though similar tectonic process The Bend Basalt Suite is intercalated with the Flake Lake Felsic Suite at the location of the 2697 Ma date. Stratigraphic relationships suggest that much of the Bend  57  Basalt Suite is coeval with some of the Flake Lake Felsic Suite. The upper domain of the stratigraphy of the Flake Lake transect contains the Windy Lake Felsic Suite intercalated with the Spyder Arm Basalt Suite (Figure 2.4). This represents contemporaneous volcanism of the Windy Lake Felsic Suite and the Spyder Arm Basalt Suite which implies that the felsic volcanic cycles were discrete while the mafic volcanism was continuous thought the evolution of the belt. The Windy Lake Felsic Suite and Spyder Arm Basalt Suite are then overlain by the Member Basalt Suite. The geochronology of the Clover Transect suggests that the rocks from this locality are younger than those from the Flake Lake Transect (west side of the belt) (Figure 2.6). In this transect, the Koignuk Felsic Suite is overlain by the Clover West Basalt Suite in the older volcanic sequence. The upper (younger) sequence is defined by mafic volcanic rocks that are overlain by sedimentary rocks (Clover Lake Sedimentary Suite) and the Clover Lake Felsic Suite (2663 Ma). The overall stratigraphic position of the Boston Area could not be completely resolved through mapping. The disconformity between the sedimentary rocks and the underlying mafic volcanic rocks in the Boston Area is based on two U/Pb ages. The sedimentary rocks on the west limb of the Boston Anticline is 2675.8±2.5 Ma and the rocks on the east limb include the Windy Lake Felsic Suite (2686 Ma) (Figure 2.9). This relationship means that the Boston Basalts Suite is older than 2686 Ma. This relationship is consistent elsewhere in the belt where Ti-enriched basalt suites similar to the Boston Ti basalts usually lie in the lower portions of the stratigraphy, below the Windy Lake Felsic Suite (2686 Ma).  58  The north part of the belt the Wolverine Transect covers a similar portion of the stratigraphy as the Doris-Discovery transect. These two transects are separated by a fault called the Hope Bay Deformation Zone which juxtaposes distinct basalt suites (Figure 2.19). The Doris-Discovery transect and the Wolverine transect contains a similar mixture of small, dark green pillowed basalt suites (Doris Basalt Suite, Kennet Tarn Basalt Suite and Patch Basalt Suite) which are separated by light green well formed pillows (Mesa Basalt Suite, Windy Basalt Suite and Wolverine Basalt Suite). This indicates that the north part of the belt contains multiple cycles of small, dark green (Tienriched) pillowed basalts separated by “normal” pillowed basalt. These suites of small dark green pillow forms are Ti-enriched basalts and are an important group of rocks discussed further in Chapter 3. They host two gold deposits in the north part of the belt. On the south side of the Hope Bay Deformation Zone the Wolverine Basalt Suite is intercalated with felsic tuffs, dated at ca. 2690 Ma. There are no suitable units to collect geochronology data from the lower part of the Doris stratigraphy, but stratigraphic relations suggest that the Patch Basalt Suite is older than 2690 Ma as parts of it lie below the Wolverine Basalt Suite. The uppermost part of the stratigraphy in the northern part of the belt is found in the Discovery Area. The age of the siltstone (2678 Ma) at discovery represents the end of the sedimentary part of the Windy Felsic Suite and gives a time range of 8 m.y. on this suite. The date of 2670 Ma on the Conglomerate Hill Suite is the youngest sedimentary rock in this study and represents sedimentation that is post-volcanic but likely preorogenic. Hebel (1999) dated a conglomerate suite bearing granitic clasts at 2647 Ma but there is no context how this suite relates to the rest of the Hope Bay Greenstone Belt.  59  There are two types of intrusives in the Discovery Area, a xenolith rich diorite and a gabbro. The gabbro is similar to gabbro seen throughout the basalt stratigraphy which is likely the same as the feldspar megacrystic gabbro at Flake Lake. The relationships in the Discovery Area suggest that all these gabbros are relatively young but likely still are within the time range of volcanism in the belt. The most interesting intrusive in the Discovery Area is the xenolith rich diorite which has a sill like geometry. These rounded xenoliths are up to 40cm in diameter. The rounding suggests mechanical abrasion or resorption as well as possible transport of significant distances. No feeder dykes have been identified and the lack of vesicles suggest a low velocity magma which would rule out mechanical abrasion. The north and south parts of the belt contain similar stratigraphy which can be correlated in places (Figure 2.19). Koignuk Felsic Suite and the Windy Felsic Suites are regionally extensive units that can be correlated between the two transects, and a sequence of conglomerates and argillites that are the youngest rocks found in the belt can be broadly correlated based on geochronology. The base of the Clover Lake and Conglomerate Hill Sedimentary Suite define the end of regional volcanism. The most voluminous felsic volcanic rocks in the south part of the belt belong to the Koignuk Felsic Suite, whereas the north part of the belt contains equal proportions of Windy Lake Felsic Suite and Koignuk Felsic Suite rocks (Figure 1.4).  2.3.2 The Belt as a Whole and Comparison to Other Greenstone Belts The original stratigraphic framework, by Hebel (1999), holds true with volcanism occurring over an interval of at least 53 million years. The felsic volcanic episodes which occur around 2716 Ma, 2697 Ma, 2690 Ma, 2686 Ma, 2677 Ma and 2663 Ma are  60  separated by the deposition of mafic or sedimentary rocks. Turbiditic sedimentation and conglomerates are syn-volcanic and post-volcanic. The felsic to mafic cycles of volcanism seen in greenstone belts worldwide are observed here (Ayer et al. 2002). The tectonics of the Archean are not well understood, we can only speculate on the geodynamic setting of greenstone belts. Despite our lack of understanding of the Archean some basic observations can be made; 1) almost all of the felsic and mafic volcanism is submarine indicated by pillowed volcanic rocks and reworking of felsic volcanic rocks and 2) there are complicated magma processes that results in mafic to felsic volcanic cycles. The plutonic activity found on the margins of the Hope Bay Greenstone Belt is marked by synvolcanic (2672 Ma, Bevier and Gebert 1991), post-volcanic/syn-D2 (2650 Ma, Bevier and Gebert 1991) intrusives and post-deformation (2608 Ma, Bevier and Gebert 1991) intrusive rocks. Titanite U-Pb cooling ages from a gneiss bordering the south eastern margin of the Hope Bay Greenstone Belt suggest the peak of regional metamorphism had occurred by ca. 2589 Ma. The temporal framework of the Hope Bay Greenstone Belt is similar to many other greenstone belts throughout the Canadian Shield. The Yellowknife Greenstone Belt has volcanism spanning 70 m.y. (2730 – 2660 Ma) as well as a significantly younger sequence of late orogenic sedimentary rocks (Henderson, 1970; Cousens et al., 2006; Martel and Lin, 2006; Davis and Bleeker 1999; Bleeker et al., 2004). The Abitibi Greenstone belt evolved over a longer time frame but is of similar age; it has volcanism spanning 45 m.y., between (2730 - 2685 Ma) and has significant late orogenic sedimentation of the Timiskaming Assemblage (Chown et al., 1992; Corfu, 1993; Ayer et  61  al., 2002). The Hope Bay Greenstone Belt is similar to both of these well documented greenstone belts in age and span of volcanism. Only one isolated location with little geologic context of late orogenic sedimentary rocks has been identified as part of the Hope Bay Sedimentary Suite (Hebel 1999).  2.4 Summary The combination of field relationships, from a number of discrete transects across the Hope Bay Greenstone Belt, and U-Pb geochronology has allowed the creation of a revised stratigraphic framework for the belt. This work confirms that volcanism occurred over an interval of at least 53 m.y. (2716 Ma to 2663 Ma) (Hebel 1999) but using field relationships and additional geochronology the majority of volcanism occurred over 33 m.y. (2700 – 2677 Ma). The stratigraphy of the Hope Bay Greenstone Belt can be broken into two main parts, that older and younger than 2686 Ma. The time horizon of 2686 Ma is the first time belt wide felsic volcanism is observed and is chosen because it can be correlated throughout the belt. This age of 2686 Ma represents the transition period in the belt’s history where mafic dominated volcanism is replaced by interbedded felsic and mafic volcanism with lesser sedimentation. In the Hope Bay Greenstone Belt mafic volcanic rocks are almost entirely made up of pillow basalts with some pillow breccia, there are also sections of massive basalt or gabbro that are often difficult to determine it they are syn-volanic or post-volcanic intrusions. The volcanic textures in the pillow basalts include vesicles, gas cavities and varioles. The felsic volcanic rock packages show a wide range of volcanic textures including those consistent with pyroclastic, resedimented syn-eruptive volcanioclastic  62  and volcanogenic sedimentary deposits. Volcanic textures of these suites show that all were deposited in a submarine environment. The stratigraphic framework of the sedimentary suites of the Hope Bay Greenstone Belt includes syn-volcanic sedimentary and post-volcanic sedimentary rocks. The sedimentary rock suites include the Boston and Glen Lake Sedimentary Suites as well as the sedimentary portions of the Windy Lake and the Koignuk Felsic Suites. The younger sedimentary suites observed in this study include Clover Lake and Conglomerate Hill sedimentary suites. These younger sedimentary suites are made up of argillites and conglomerates. In the north and south part of the belt the oldest rocks observed are found on the east side of the belt and the youngest rocks (sedimentary) are found in approximately the middle of the belt. Other than this, the north and south part of the belt differ due to the fact that the south part has a number of stratigraphic packages that are juxtaposed against each other by a number of faults, whereas in the north part of the belt the rocks are relatively stratigraphically continuous. In the Hope Bay Greenstone Belt, gold deposits are broadly associated with favorable lithologic host rock and structural features (large scale folds or faults). In the north part of the Hope Bay Greenstone Belt the Doris Deposit and Madrid Area Deposits are hosted in high titanium mafic volcanic suites, these are located in the lower portions of the stratigraphy, (older than 2690 Ma). The Doris Deposit is hosted in the oldest known rocks in the north part of the belt, with the Madrid deposits hosted stratigraphically higher in the same mafic volcanic secession. The Boston Deposit which  63  is located in the south part of the belt is hosted in sedimentary rocks, dated at 2675 Ma, as well as basalts older than 2686 Ma. A major part of the exploration methodology in the Hope Bay Greenstone Belt has been based on identifying and understanding these favorable basalt rock suites, notably the Doris and Patch Basalt Suites. Less voluminous but similar suites to the Doris and Patch Basalt Suites exist elsewhere in the belt and may hold great exploration potential. Understanding the supracrustal succession in the Hope Bay Greenstone Belt is complicated by its structural complexity and long history. The Hope Bay Greenstone Belt was created by a number felsic and mafic volcanic events, that have a variety of compositions, and the belt also contains syn-volcanic and post-volcanic sedimentation. These findings are consistent with that of numerous other greenstone belts in the Slave Structural Province, Canadian Shield and the World.  64  65  (pg)  Pb5 Th/U6  ± 0.09 ± 0.13 ± 0.10 ± 0.10 ± 0.13  13.1049 13.0533 13.0251 12.8871 13.0974  13.2510 13.3197 13.2267 13.2276  Pb/  U  ± 0.12 ± 0.15 ± 0.13 ± 0.13 ± 0.15  ± 0.41 ± 0.51 ± 0.38 ± 0.45  235  Pb/  0.18360 0.18365 0.18334 0.18259 0.18373  Pb  U  ± 0.06 ± 0.08 ± 0.05 ± 0.06 ± 0.07  0.886331 0.866261 0.918299 0.913657 0.903059  ± 0.11 0.96640 ± 0.26 0.866515 ± 0.14 0.933982 ± 0.11 0.970830  206  0.18494 0.18472 0.18433 0.18411  207  0.51266 0.50573 0.48980 0.50495  ± 0.12 ± 0.23 ± 0.23 ± 0.10  13.0197 12.8449 12.4039 12.7969  U spike.  1.0 2.4 5.3 2.4  0.9 2.6 0.0  -0.2 0.3 0.2 0.5 0.0  0.0 -0.7 -0.4 -0.6  discordant  %9 Pb/  ± 4.1 ± 5.6 ± 4.3 ± 4.2 ± 5.5  2668.0 2638.4 2569.8 2635.0  ± 5.3 ± 10.1 ± 9.9 ± 4.3  Pb and the  207  Pb/  206  Pb age of fraction.  207  Pb/204Pb = 15.8-15.5 ± 3%,  208  Pb/204Pb = 36.4 ± 0.5%.  ± ± ± ± ±  2.3 2.9 2.4 2.4 2.8  7.7 9.6 7.1 8.6  2685.7 2686.1 2683.3 2676.5 2686.8  Correlation coefficient.  Pb/206Pb age of each fraction (Stacey and Kramers, 1975).  2.0/2.0 2.5/2.5 1/8/1.8 1.8/1.8 2.1/2.1  ± 3.5/3.5 ± 8.4/8.5 ± 4.5/4.5 ± 3.6/3.6  Pb/206Pb  2697.6 2695.7 2692.3 2690.3  207  2681.1 2668.3 2635.5 2664.8  ± ± ± ±  3.1 5.2 5.0 2.9  2691.0 2691.2 2686.3 2687.5  ± 2.2/2.2 ± 3.4/3.4 ± 3.1/3.1 ± 2.5/2.5  2682.5 ± 3 2691.1 ± 2.4/2.4 2663.7 ± 2.8 2688.3 ± 2.2/2.2 2690.2 ± 3.5 2690.5 ± 2.3/2.3  2687.2 2683.5 2681.5 2671.4 2686.7  ± ± ± ±  Pb/235U  2697.7 2702.6 2696.0 2696.0  207  Fractionation, blank and common Pb corrected; Pb procedural blanks were ~0.5-2.0 pg and U <0.2 pg. Common Pb compositions are based on Stacey-Kramers model Pb at the  Model Th/U derived from radiogenic  208  Total common Pb in analysis based on blank isotopic composition: 206Pb/204Pb = 18.5 ± 3%,  Measured ratio corrected for spike and Pb fractionation.  U  Apparent ages ±2V,Ma 7  ± 16.9 ± 17.8 ± 14.7 ± 18.6  238  2670.9 ± 5.0 2631.3 ± 4.3 2689.8 ± 6.4  2689.3 2680.1 2679.0 2664.7 2686.5  2697.8 2711.8 2700.9 2703.7  206  Radiogenic Pb; all raw Pb data corrected for fractionation of 0.32-0.23/amu ± 20% determined by repeated analysis of NBS-982 reference material.  233-235  ± 0.17 0.184191 ± 0.07 0.933907 ± 0.27 0.184211 ± 0.1 0.931284 ± 0.27 0.183672 ± 0.09 0.939666 ± 0.15 0.18380 ± 0.08 0.912976  0.51335 ± 0.12 13.0386 ± 0.16 0.18421 ± 0.07 0.903831 0.50407 ± 0.10 12.7811 ± 0.15 0.18390 ± 0.07 0.940886 0.51779 ± 0.15 13.1464 ± 0.19 0.184144 ± 0.07 0.935317  0.51768 0.51550 0.51525 0.51189 0.51701  U  207  Isotopic ratios ±1V,% 7  ± 0.38 ± 0.40 ± 0.33 ± 0.42  238  Discordance in % to origin. H. Lin carried out mineral separations and provided assistance with mass spectrometry; assitance with grain selection, abrasion and in the cleanlab provided by R. Lishansky.  9  8  1.5 0.16 5.3 0.189 5.7 0.103 1.7 0.34  Pb/  0.51967 0.52299 0.52041 0.52108  206  U blank correction of 0.2 pg ± 20%; U fractionation corrections were measured for each run with a double  single grain analyses; all air abraded.  207  7  6  5  4  3  2  1  d) AJS3 (Nad83, Zone 13N 433414, 7549980) A 4 110.5 59.9 9199 B 2 92.6 49.8 1122 C 7 40.7 20.8 1546 D 2 119.6 66.4 4535  c) AJS4 (Nad83, Zone 13N 434907, 7546452) A 5 175.6 93.2 11260 2.5 0.066 B 5 186.9 98.2 20020 1.5 0.100 D 2 312.3 172.4 5022 4.0 0.201  3.4 2.7 0.7 1.6 1.1  0.628 0.672 0.636 0.633 0.610  Pb  Pb4  b) AJS5 (Nad83, Zone 13N 441634, 7510788) A 7 65.7 39.7 4378 B 5 52.7 32.4 3152 C 4 46.3 27.9 8117 D 4 91.9 55.0 7191 E 5 47.3 28.5 6678  (ppm)  206  204  0.538 0.574 0.595 0.626  (ppm)  (Pg)  Pb*3  a) AJS1 (Nad83, Zone 13N 445023, 7515114) A 6 31.4 18.7 2715 2.2 B 7 29.8 18.0 308.3 22.8 C 7 28.9 17.5 2719 2.4 D 6 30.2 18.4 4003 1.5  U2  Wt  Table 2.1 U-Pb TIMS analytical data  Fraction1  66  U2  Pb*3  206  204  Pb4  Pb5 Th/U6  13.1009 12.9898 12.9446 12.9136 12.9853  ± 0.21 ± 0.15 ± 0.12 ± 0.17 ± 0.27  ± 0.28 ± 0.20 ± 0.11 ± 0.27 ± 0.13  ± 0.18 ± 0.13 ± 0.16 ± 0.23 ± 0.41  U  Pb/  0.18346 0.18251 0.18274 0.18194 0.18321  0.18280 0.18338 0.18290 0.18321 0.18334  Pb  U spike.  0.964153 0.907404 0.916194 0.897069 0.960957  0.953237 0.958597 0.914630 0.977950 0.931670  0.781775 0.840805 0.808635 0.599397 0.599456  U  -0.3 -0.3 0.2 -0.3 0.4  16.6 -0.5 0.2 -0.3 0  1.9 5.5 7.6 2.8 -0.1  discordant  %9 Pb/  2690.3 2683.1 2672.7 2677.0 2673.9  2304.7 2693.8 2675.5 2689.7 2683.5  2642.7 2555.3 2525.1 2626.3 2691.6  206  ± 8.4 ± 5.8 ± 3.6 ± 6.8 ± 11.4  ± 10.1 ± 8.4 ± 3.3 ± 11.2 ± 4.5  Pb and the  207  Pb/  206  Pb age of fraction.  207  Pb/204Pb = 15.8-15.5 ± 3%,  208  Pb/204Pb = 36.4 ± 0.5%.  2686.9 2678.9 2675.6 2673.4 2678.6  2508.8 2688.0 2677.7 2685.4 2683.4  ± ± ± ± ±  ± ± ± ± ±  ± ± ± ± ±  3.9 2.9 2.2 3.2 5.1  5.1 3.8 2.1 5.0 2.4  3.4 2.5 2.9 4.3 7.7  Pb/235U  2666.8 2623.1 2620.6 2661.0 2690.6  207  2684.4 2675.8 2677.9 2670.6 2682.1  2678.4 2683.7 2679.4 2682.1 2683.3  Correlation coefficient.  Pb/206Pb age of each fraction (Stacey and Kramers, 1975).  ± 1.8/1.8 ± 2.1/2.2 ± 1.7/1.7 ± 2.5/2.5 ± 2.5/2.5  ± 2.8/2.8 ± 1.9/1.9 ± 1.7/1.7 ± 1.9/1.9 ± 1.7/1.7  ± 4.0/4.0 ± 2.5/2.5 ± 3.6/3.6 ± 6.0/6.0 ± 10.8/10.9  Pb/206Pb  2685.2 2675.8 2695.3 2687.5 2689.8  207  Apparent ages ±2V,Ma 7  Fractionation, blank and common Pb corrected; Pb procedural blanks were ~0.5-2.0 pg and U <0.2 pg. Common Pb compositions are based on Stacey-Kramers model Pb at the  Model Th/U derived from radiogenic  208  Total common Pb in analysis based on blank isotopic composition: 206Pb/204Pb = 18.5 ± 3%,  Measured ratio corrected for spike and Pb fractionation.  U  ± 4.2 ± 3.9 ± 2.7 ± 5.8 ± 9.2  238  Radiogenic Pb; all raw Pb data corrected for fractionation of 0.32-0.23/amu ± 20% determined by repeated analysis of NBS-982 reference material.  233-235  ± 0.06 ± 0.07 ± 0.05 ± 0.08 ± 0.08  ± 0.08 ± 0.06 ± 0.05 ± 0.06 ± 0.05  ± 0.12 ± 0.07 ± 0.11 ± 0.18 ± 0.33  206  0.183545 0.182513 0.184672 0.183805 0.184065  207  Discordance in % to origin. H. Lin carried out mineral separations and provided assistance with mass spectrometry; assitance with grain selection, abrasion and in the cleanlab provided by R. Lishansky.  9  8  ± 0.19 ± 0.13 ± 0.08 ± 0.15 ± 0.26  (Nad83 13N 429456, 7558010) 61800 0.6 1.100 0.51791 8580 0.6 0.394 0.51620 12550 1.1 0.763 0.51376 12500 0.5 0.539 0.51478 5646 0.8 0.547 0.51405  10.8320 13.1158 12.9732 13.0787 13.0517  12.8240 12.2417 12.2092 12.7454 13.1515  Pb/  235  U blank correction of 0.2 pg ± 20%; U fractionation corrections were measured for each run with a double  207  7  6  5  4  3  2  ± 0.26 ± 0.18 ± 0.08 ± 0.25 ± 0.10  U  207  Isotopic ratios ±1V,% 7  (Nad83 13N 429456, 7558010) 5421 1.7 5.012 0.42977 9971 1.4 0.632 0.51872 8579 1.6 0.557 0.51442 10380 1.1 0.581 0.51775 13430 0.8 0.530 0.51632  single grain analyses; all air abraded.  55.7 15.7 66.1 19.9 26.8  g) LMB056 detrital zircons A 13 83.9 B 6 27.3 C 4 107.1 D 6 33.7 E 3 45.4  1  55.9 32.5 49.7 68.2 65.3  f) LMB055 detrital zircons A 6 58.6 B 8 53.6 C 5 83.9 D 3 113.9 E 3 110.5  Pb/  238  ± 0.10 ± 0.09 ± 0.07 ± 0.13 ± 0.21  206  0.50674 0.48646 0.4795 0.50292 0.5182  (Pg) (ppm) (ppm) Pb (pg) e) AJS6 detrital zircons (Nad 83, 13N 440607, 7503775) A 6 141.8 87.0 674.9 41.0 0.801 B 5 140.2 80.7 1921 11.2 0.696 C 8 112.9 61.0 760.7 36.4 0.455 D 3 59.0 37.1 951.2 6.0 0.960 E 2 43.4 29.0 452.4 6.5 0.938  Wt  Table 2.1 continued. U-Pb TIMS analytical data  Fraction1  Table 2.2: Summary of published U/Pb geochronology Suite Name Rock Type Age (Ma) 2 ı error (Ma) Flake Lake Rhyolite 2716.3 +3.1 / -2.6 2698.7 +6.1 / -3.7 Wolverine Lake quartz-feldspar porphyry Felsic Tuff 2690.2 +3.6 / -2.8 Square Lake Square Lake Felsic Flow 2690 +2.0 / -1.5 felcis Tuff 2685.2 +2.9 / -2.5 Windy Lake Windy Lake lapilli tuff 2685.8 +2.9 / -1.5 2685.6 +1.8 / -1.6 Son Volt lapilli tuff 2685.1 +3.2 / -2.0 Windy Lake quartz-feldspar porphyry 2677.9 +5.8 / -1.4 Koignuk quartz-feldspar porphyry Koignuk Fesic Flow 2677.4 +1.9 / -1.5 Fesic Flow 2677.2 +2.5 / -1.1 Koignuk Fesic Tuff 2677.6 +1.9 / -1.9 Koignuk Clover Lake Rhyolite 2662.7 +3.4 / -2.8 Sandusky Diorite 2663.2 +15.1 / -10.1  Referance (inheratence issues)Hebel 1999 (inheratence issues) Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999  Sandusky  Diorite  2662.4 +18.7 / -13.1 Hebel 1999  Group I Hope Bay Hope Bay Hope Bay Wilco Windy Lake  2649.5 +2.9 2701.1 +4.6 2685.9 +2.4 2647.2 +2.8 2675 +3.0 2685 +4  n/a  Foliated Gniess Granitoid clast Granitoid clast sandstone sandstone Foliated Quartz porphyry feldspar porphyry hornblende granodiorite hornblende-biotite granite Granitic pegmatite  Hope Bay  conglomerate  Square Lake QSP Windy Lake Wolverine Lake  volcaniclastic dacite dacite quartz-feldspar porphyry  Koignuk River Group II Group III  / / / / / /  -2.5 -3.8 -2.3 -2.8 -3.0 -2  Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Hebel 1999 Bevier and Gebert 1991  2677 +3 2672 +3  / -1 / -1  Bevier and Gebert 1991 Bevier and Gebert 1991  2608 +5  / -5  Bevier and Gebert 1991  1910 +1.7  / -1.7  Bevier and Gebert 1991  2715 +7  / -7  Padgham 1996 (no error from author) Sherlock unpublished data 1998 Sherlock unpublished data 1999 Sherlock unpublished data 2000 Sherlock unpublished data 2001  2689.4 +4 2681.5 +4.9 2683.4 +2.1 2686 +3.6  / / / /  -3.6 -4.9 -2.1 -3.6  67  420000  435000  450000 7575000  Arctic Ocean Roberts Bay  Doris Lake  Windy Lake  7560000  7560000  Hope Bay  Doris-Discovery Transect Figure 2.13,2.14 & 2.15  South Doris Transect Patch Lake  7545000  7545000  Wolverine Transect Figure 2.11 & 2.12  Granitoids 7530000  7530000  Granitoids  Flake Transect Figure 2.2 & 2.3  Clover Transect Figure 2.5 & 2.6  10  7485000  Kilometers  7500000  7500000  420000  Spyder Lake  Boston Transect Figure 2.8 &2.9  0 2.5 5  7515000  7515000  Flake Lake  435000  450000  68  Figure 2.1: The Hope Bay Greenstone Belt with six transects mapped in this study outlined in red  439000  440000  441000  442000  443000  445000  444000  446000  447000  448000  7519000  7519000  FLS 500  1,000  2,000  3,000 Meters  2716+3.1/-2.6 Ma Flake Lake  7517000  7517000  78 81 81  86  78 80  79 90  MB  82  439000  Overall Facing Direction U/Pb Geochronology location and age Pillow Overturned  Pillow Tops  Synvolcanic Mafic Intrusive Rocks Felsic Volcanic Rocks Intermediate to Felsic Volcanic Rocks  Bedding Mafic Volcanic Rocks: Normal  90  SAB WLS  440000  441000  2685±2.0Ma  442000  Bedding tops Foliation  443000  444000  Mafic Volcanic Rocks: Titanium  445000  446000  447000  448000  7511000  7511000  Spider Lake  Early Granites (Synvolcanic)  Inferred Fault  85 81  86 87  Inferred lithologic contact Archean Rocks  88  7512000  7512000  2685+4/-2Ma  Extent of transect  7513000  Member Lake  7513000  80  80  River Bend Area 7514000  82  spider arm  7514000  87  2697.4± 5.4Ma  7515000  7515000  10 Km  81  80  77 0  71  7516000  7516000  BB 82  7518000  7518000  0  Figure 2.2 : Geology of the Flake Lake transect showing the distribution of rock types. The rocks are divided into suites based on field relationships and chemical composition. Suites: FLS: Flake Lake Felsic Suite, BB: Bend Basalt Suite, MB: Member Basalt Suite, SAB: Spider Arm Basalt Suite, WLS Windy Lake Felsic Suite. Inset map: Outline of the Hope Bay Greenstone Belt with mapped transect outlined in red  69  Member Basalt Suite 3000 m  100 m  well formed pillows and pillow breccia with some massive flows/gabbro  Windy Dacite Unit (2685 Ma)  Spider Arm Basalt Suite 1000 m  750 m  Pale green classic shaped pillows with ± gas cavities ± varioles  Younger Domain  Windy Lake Felsic Suite (2686 Ma) structural juxtaposition  Feldspar porphyritic Gabbro with Flake Lake zenoliths  Older Domain  2700 m  Flake Lake Suite (2697 Ma) volcaniclastic facies  Bend Enriched Basalts Good pillows shapes intercalated with Flake Lake felsic volcanics and intrude by Flake Lake Suite dykes  1000 m  Flake Lake Suite (2716 Ma) Quartz phyric massive rhyolite  300 m  Figure 2.3 Reconstructed stratigraphic column for the Flake Lake Transect, suites are presented in proper stratigraphic order. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks. 70  a  b  c  d  e  f  Figure 2.4 a) Field photograph of volcaniclastic rhyolite from the Flake Lake Suite, silica rich clast (light grey) in crystal (light grey) and ash (brown) matrix b) Field photograph of pillow from the Bend Basalt Suite, with 3cm dark brown pillow selvage c) Field photograph of vesicular-amygdaloidal and plagioclase porphyritic pillow basalt with ~1.5cm brown pillow selvage from Member Basalt Suite d) Field photograph of numerous gas cavities in pillow basalt from the Spider Arm Basalt Suite, pillow shapes obscured by lichen e) Field photograph of monomictic volcanic conglomerate with immature sand matrix, this facies is part of Windy Lake Felsic Suite f) Field photograph of well bedded siltstone showing crossbedding and flame structures, this is part of the sedimentary facies of the Windy Lake Felsic Suite (scribe for scale, length 15cm) 71  7507000  7506000  72  10 Km  77 62  7505000  7504000  500  433000  0  434000  436000  Foliation  83  64 88 64  435000  2,000  75  90  Bedding tops  Bedding  Pillow Tops  Pillow Overturned  U/Pb Geochronology location and age  Overall Facing Direction  Inferred Fault  437000  69  90  436000  3,000 Meters  CWB  87  8683  63 51  437000  79  77 83  88  83  Early Sedimentary Rocks  87  84  86  86  Mafic Volcanic Rocks: Normal  80  CS  438000  84  87  84  84  CEB  439000  80  85  Lake  85  84  79  87 90  80 Spyder  439000  2662.7 +3.4/-2.8 Ma  86  CFS  438000  Clover Lake  80  Intermediate to Felsic Volcanic Rocks  Felsic Volcanic Rocks  Synvolcanic Mafic Intrusive Rocks  Early Granites (Synvolcanic)  Inferred lithologic contact Archean Rocks  75  50  83  435000  Extent of transect  434000  7504000  1,000  KFS  2677Ma  85  0  433000  7505000  g  7508000  7506000  Koi  7509000 7507000  iver  7508000  nu k R  7509000 7503000  7503000  Figure 2.5: Geology of the Clover transect showing the distribution of rock types. The rocks are divided into suites based on field relationships and chemical composition. Suites: CEB: Clover East Basalt Suite, CS: Clover Sedimentary Suite, CFS Clover Felsic Suite, CWB: Clover West Basalt Suite, KFS: Koignuk Felsic Suite Inset map: Outline of the Hope Bay Greenstone Belt with transect outlined in red  Clover Lake Felsic Suite (2662 Ma) <400 m  Clover Sedimentary Suite epiclastic felsic to conglomerate to siltstones to argillite  Clover East Basalt Suite Pale green coloured Pillows with variolitic horizon  >200 m  Younger Domain  structural juxtaposition Older Domain  Clover West Basalt Suite ~600 m  Succession of pillow basalts with significant subvolcanic sill and minor mafic volcaniclastics  Volcanic-sedimentry Rocks; crystal rich (epiclastic tuff?) To wacky Rhythmite Horizon Volcaniclastic facies >1000 m  Coherent crystal rich (tuff?)  Koignuk Felsic Suite (2677 Ma)  Lobe and Breccia facies  Figure 2.6 Reconstructed stratigraphic column for the Clover Transect. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  73  a  b  d Massive dolomite  c  dolomite rhythmite  f  e  Figure 2.7 a) Field photograph of conglomerate with mostly sedimentary clasts in a immature sand matrix, from the Clover Sedimentary Suite b) Field photograph of a epiclastic volcaniclastic rock at the base of the Clover Sedimentary Suite c) Polished slab photograph of black matrix breccia, rhyolite clasts (porphyritic and choheent) in a black argillite matrix, from the Clover Felsic Suite, d) Field photograph of a massive dolomite bed and thinly bedded dolomite rhythmite of the to of the Koignuk Felsic Suite e) Polished slab photograph of the crystal tuff facies from the Koignuk Felsic Suite f) Field photograph of lapilli tuff from the Koignuk Felsic Suite (scribe for scale, length 15cm) 74  440000  441000  442000  443000  Legend Extent of transect Inferred lithologic contact Inferred Fault  79  Lineation Bedding  7505000  7505000  Spider Lake  Foliation Overall Facing Direction  U/Pb Geochronology location and age Archean Rocks  69  Early Sedimentary rocks  87  Synvolcanic Mafic Intrusive rocks 10 Km  69 75  2675± 2.5Ma  Mafic Volcanic rocks: Pillows/ Variolitic Pillows  86  Mafic Volcanic Rocks: Ti enriched basalt  64  7504000  7504000  0  Stickleback Lake  54 85 66  7503000  7503000  62  BS 73  73 85  0  200 400  800  80  BB 440000  441000  442000  443000  7502000  7502000  BS  Meters  Figure 2.8: Geology of the Boston Area showing the distribution of rock types. The rocks are divided into suites based on field relationships and chemical composition. Suites: BS Boston Sedimentary Suite, BB Boston Basalt Suite, which includes non-variolitic, variolitic and Ti-enriched basalts Inset map: Outline of the Hope Bay Greenstone Belt with transect in red  75  Boston Sedimentary Suite (2675 Ma) and Windy Lake Suite (2686 Ma) (wacke to siltstone with minor argillite)  >300 m  disconformity Volcaniclastic Rocks  50 m  150 m  Variolitic Pillow Basalt Suite  Pillow Basalt Suite (Normal pillow basalts with minor Ti enriched pillow basalts at base)  >450 m  Figure 2.9: Reconstructed stratigraphic column for the Boston Area. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  76  a  b  c  d  f  e Figure 2.10 a) Field photograph of highly altered pillow basalts from the Boston Basalt Suite b) Field photograph variolitic pillow basalt from the Boston area, light brown coalesced varioles at center of pillow c) Field photograph of pillowed Ti basalt from the Doris Basalt Suite d) picture of polished slab of Doris Basalt Suite e) Field photograph of Mesa Basalt Suite, f) Picture of polished slab of Mesa Basalt Suite (scribe for scale, length 15cm)  77  75  7550000  7549000  84 86  KB  79  79  78  7548000  7547000  434000  WFS  Patch Lake  82  435000  WVB  2691.1±2.0Ma  80  Wolverine Lake  62  2689.4+4.0/-3.6Ma 2684.2 +/- 3.6 Ma  Meters  1,500  WVB  76  7547000  433000  1,000  86  88  2691.7 ±2.5Ma  Mafic Volcanic Rocks: High Titanium  Mafic Volcanic Rocks: Normal  tion Zone  250 500  88  Foliation  Bedding tops  Bedding  Pillow Tops  Intermediate to Felsic Volcanic Rocks  Felsic Volcanic Rocks  Pillow Overturned  Synvolcanic Mafic Intrusive rocks  Overall Facing Direction  U/Pb Geochronology location and age  Deforma  432000  435000  Early Granites (Synvolcanic)  Archean Rocks  434000  7548000  0  KTB  86  Kennet Tarn Lake  WLS  88  Inferred Fault  Inferred lithologic contact  Extent of transect  433000  Hope Bay  10 Km  KFS  83  Windy Lake  432000  7549000  431000  0  431000  7550000 7546000  7546000  Figure 2.11: Geology of the Wolverine Transect showing the distribution of rock types. The rocks are divided into suites based on field relationships and chemical composition. Suites: WVB Wolverine Basalts, WFS Wolverine Felsic Suite, KTB Kennet Tarn Basalts, WLS Windy Lake Felsic Suite, KB Koig Basalts, KFS Koignuk Felsic Suite, Inset map: Outline of the Hope Bay Greenstone Belt with transect outlined in red  Koignuk River Fault feldspar porphyritic tuff  Koignuk Felsic Suite (2677 Ma)  >800 m  Breccia to lipilli tuff  Koig Basalt Suite 600 m  LREE Basalts  Pale green colored Normal and LREE Pillow Basalts  Windy Lake Felsic Suite (2686 Ma) Bedded volcanic derived  200 m  wacke’s  Patch Basalt Suite  ~400 m  dark green small pillow basalts with massive sections  1000 m  Dacite interlayer (2691Ma±2.5 Ma )  Wolverine Basalt Suite Thick susession of classic shaped Pillow basalts and minor massive sections 145 m Volcanic conglomerate (2689 +4.0/-3.6Ma)  250 m  540 m  Wolverine porphyry  Wolverine Intrusive Suite (2686 Ma)  500 m  Dacite interlayer (2691.1±2.0 Ma)  Hope Bay Deformation Zone Figure 2.12 Stratigraphic column for the Wolverine Transect. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  79  428000  429000  430000  431000  432000  433000  434000  435000  2685.1 +3.2/-2.0 Ma 250 500  1,000 Meters  7561000  7561000  0  WB  68  77  .  7559000  81  ?  10 Km  79  Discovery Bay  Doris Doris North Lake Gold Deposit  ?  PB  2678.4±2.8Ma 7558000  87  84  MB  7558000  0  87 84  Legend  ?  82  2670.6 ±2.5Ma  Inferred Fault  ?  76  7556000  42  Late Mafic Intrusive rocks  Inferred lithologic contact  GSS  Hope Bay  Archean Rocks  Extent of transect  DYB  Late Sedimentary Rocks  Overall Facing Direction  Early Sedimentary Rocks  U/Pb Geochronology location and age  Early Granites (Synvolcanic)  Pillow Overturned  Synvolcanic Mafic Intrusive Rocks  Pillow Tops  Felsic Volcanic Rocks  Bedding  7557000  38  7559000  WLS  7557000  DB  73 87  Intermediate to Felsic Volcanic Rocks  Bedding tops  CHS  Mafic Volcanic Rocks: Normal/Titanium  Foliation  7556000  7560000  Glen Lake  7560000  75  KFS 428000  429000  430000  431000  432000  433000  434000  435000  Figure 2.13: Geology of the Doris-Discovery Transect showing the distribution of rock types. The rocks are divided into suites based on field relationships and chemical composition. Suites: DB Doris Basalt Suite, MB Mesa Basalt Suite, PB Patch Basalt Suite, WB Windy Basalt Suite, WLS Windy Lake Felsic Suite, DYB Discovery Basalt Suite, GSS Glen Lake Sedimentary Suite, CHS Conglomerate Hill Sedimentary Suite, KFS Koignuk Felsic Suite Inset map: Outline of the Hope Bay Greenstone Belt with transect in red  80  Discovery area stratigraphy Figure 2.15 continued  >500 m  Massive weakly bedded quartz feldspar poryphritic Windy Lake Felsic Suite (2686 Ma)  430 m  700 m  Volcanic conglomerate  Intrusive component, quartz feldspar poryphyritic  Windy Basalt Suite Variolitic Normal Basalis  330 m  350 m  Patch Basalt Suite Number of flows of small dark green Pillows  Mesa Basalt Suite Classic shape pillows with some mattress pillows  1000 m  140 m 150 m 250 m  Doris Basalt Suite Strongly variolitic pillows Mesa Basalt Suite Doris Basalt Suite Number of flows of small dark green pillows  Figure 2.14 Stratigraphic column for the Doris-Discovery Transect. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  81  Figure 2.15 Stratigraphic column for the Doris-Discovery Transect. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  82  475 m  375 m  >700 m On Surface Units pinch out to north  750 m  600 m  200 m  300 m  Gabbro  thinly bedded argillites with some sandy beds Discovery North  Conglomerate Hill Sedimentary Suite (2670 Ma)  Fault  Dominted by well bedded immature Siltstone  Glen Sedimentry Suite (2678 Ma)  Highly carbonated altered pillow basalts with significant gabbro intrusions  Discovery Basalt Suite  Hornblende Diorite  Pebble conglomerate interbedded with course sand layers Hornblende Diorite  Conglomerate Hill Sedimentary Suite  Continued from Figure 2.14  Discovery South  a  b  d c  e  g  f  Figure 2.16 a) Field photograph of Ti pillow basalt of the Patch Basalt Suite b) Photograph of Ti basalts of the Patch Basalt Suite c) Field photograph varioles from Windy Basalt Suite d) Field photograph of mega pillow in the Mesa Basalt Suite e) Field photograph volcanic conglomerate of the Windy Lake Felsic Suite f) Photography of the volcanic conglomerate of the Windy Lake Felsic Suite g) Field photograph of pillowed Ti Basalt from the Doris Basalt Suite inset picture of polished slab of Doris Basalt Suite (scribe for scale, length 15cm)  83  2701.1 +4.6/-3.8 Ma (clast) 2685.9 +2.4/-2.3 Ma (clast) 2647.2 +2.8/-2.8 Ma(max age)  Figure 2.18 Locations of U/Pb geochronology samples, Bold ages from this study (geology from Miramar Hope Bay compilation, 2003, Dating: Bevier and Gebert 1991; Hebel 1999; R. Sherlock, pers comm, 2001)  2685.1 +3.2/-2.0 Ma  Doris  Legend  !!  2678.4 ±2.8  Archean Rocks  2670.6 ±2.5  Late Sedimentary Rocks  2685.8 +2.9/-2.5 Ma  !  2677.4 +1.9/-1.5 Ma  Madrid !  Late Granites  2691 +2.5/ -2.5  2663.2 +15.1/-10.1 Ma  Late Mafic Intrusive Rocks  2691 +2.1/ -2.0  Early Sedimentary Rocks  2698.7 +6.1/-3.7 Ma  2690.0 +2.0/-1.5 Ma  Early Granites (Synvolcanic) Synvolcanic Mafic Intrusives  <2675.1 +3.0/-3.0 Ma  Mafic to Intermediate Volcanic Rocks 2685.6 +1.8/-1.6 Ma 2690.2 +3.6/-2.8 Ma  Felsic Volcanic Suites 2662.4 +18.7/-13.1 Ma  Unassigned Felsic rock Clover Lake Suite Koignuk Suite Windy Lake Suite 2716.3 +3.1/-2.6 Ma  Square Lake Suite  2697.4 +5.4/ -5.4  Flake Lake Suite  !  2685 +2.0/ -2.0  2685 +4/-2 Ma  ! 2662.7 +3.4/-2.8 Ma  2685.2 +2.9/-2.5 Ma  Boston ! 2677.2 +2.5/-1.1 Ma  2675 +2.5/ -2.5  0 2677.9 +5.8/-1.4 Ma  2649.5 +2.9/-2.5 Ma 2589.4 +2.2/-2.2 Ma (t)  2677.6 +1.9/-1.9 Ma  84  5  10  20 Kilometers  a) AJS-01 (Flake Lake Suite)  2692  206  Pb/  238  0.519  2716  206  0.524  Pb/238U  U  0.528  b) AJS-05 (Windy Felsic Suite)  2712  2690 2688  2708  2686  0.517  2704  2684  2700  2682  2696  0.520  2692  2680  2688  2678  2684  Concordia Age = 2697.4 ±5.4 Ma, ±8.9 @95% confidence MSWD = 2.7, Probability of concordance = 0.10  0.516  207  Pb/235U  0.512 13.0  13.1  13.2  13.3  13.4  13.5  c) AJS-04 (Square Lake Suite)  0.515  Intercepts 2685 ±2 MSWD = 0.050 207  Pb/235U  0.513 12.96  13.00  13.04  13.08  13.12  13.16  d) AJS-03 (Square Lake Suite)  U  0.52  Pb/  2660  2690 0.51  206  0.518  2680  2700  238  0.522  2680  0.514  2640  2670 2620  2660  0.50  238  U  0.510  0.502  Pb/  0.49  Intercepts 2691.7 ± 2.5 & 250 ± 180 Ma MSWD = 1.7  206  Intercepts 2691.1 ± 2.0 & 237 ± 250 Ma MSWD = 0.82  0.506  207  Pb/235U  207  Pb/235U  0.498 12.6  12.8  13.0  0.48 12.1  13.2  12.3  12.5  12.7  12.9  13.1  Figure 2.17 U/Pb concordia diagrams from volcanic rocks of the Hope Bay Greenstone belt  85  13.3  e) AJS-06 (Boston Sedimentary Suite) 2720  0.522  2700 2680  206  0.52  f) LMB-55 (Glen Lake Sedimentary Unit)  0.520  2660 2640 2620  0.50  Max Age of 2678.4±2.8Ma  206  0.51  Pb/238U  Pb/238U  0.53  2694 2690  0.518  2686  2600  Max Age of 2675.8±2.5Ma  2682  0.516  0.49  2678 2674 0.514  0.48  2670  207  Pb/  0.47 11.8  12.2  12.6  13.0  207  Pb/235U  235  U  13.4  0.512 12.85  12.95  13.05  13.15  0.521  Max Age of 2670.6±2.5Ma 2696 2692  206  0.519  Pb/238U  g) LMB-56 (Conglomerate Hill Sedimentary Suite)  2688  0.517  2684 2680  0.515  2676 2672  0.513 2668  0.511  207  Pb/235U  0.509 12.8  12.9  13.0  13.1  13.2  Figure 2.17 continued U/Pb concordia diagrams from sedimentary rocks of the Hope Bay Greenstone belt  86  13.25  Clover Lake Felsic Suite (2662Ma)  Clover Lake Transect  Clover Sedimentary Suite  Figure 2.19 Stratigraphic reconstruction comparing the north and south parts of the Hope Bay Greenstone Belt. Width of does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  Doris-Discovery Transect  Clover East Basalt Suite B a se  fault  Conglomerate Hill Sedimentary Suite (2670Ma)  of Se dimen tary S uites  Clover West Basalt Suite  Koignuk Felsic Suite (2677Ma)  Wolverine Transect Koignuk Felsic Suite (2677Ma)  c elsi ) F k a 7M gnu Koi e (267 t Sui  Koignuk River Fault  Koignuk Felsic Suite (2677Ma)  Gabbro  Glen Sedimentry Suite (2678Ma)  fault  Boston Sedimentary Suite (2675Ma)  Discovery Basalt Suite  LREEBasalt BasaltsSuite Koig  Member Basalt Suite  Host to Boston Deposit  disconformity  Boston Basalt Suite  Kennet Tarn Basalt Suite Windy Dacite Unit (2685Ma)  Boston Transect  Spyder Arm Basalt Suite  Windy Lake Felsic Suite (2686Ma) Windy Lake Felsic Suite (2686Ma)  Windy Lake Felsic Suite (2686Ma)  Wolverine Basalt Suite (2690Ma)  Windy Lake Felsic Suite (2686Ma) fault  Windy Basalt Suite  Wolverine Intrusive Suite (2686Ma)  Host to Madrid Deposits  Wolverine porphyry  Hope Bay Deformation Zone  Patch Basalt Suite HUnit Flake Lake Suite Bend Basalt Suite (2716 Ma and 2697Ma)  South 87  Doris Basalt Suite  Mesa Basalt Suite  nZ on e  Host to Doris Deposit  Flake Lake Transect  op s ex e B te ay nd De bel fo ow Mesa Basalt Suite rm ati o  Patch Basalt Suite  Doris Basalt Suite Mesa Basalt Suite Doris Basalt Suite  North  CHAPTER 3 Geochemical Evolution of the Hope Bay Greenstone Belt  88  3.1 Introduction and Methodology The late Archean Hope Bay Greenstone Belt is made up of a number of packages of mafic, felsic and sedimentary rocks. There is a gap in the understanding between the large amount of data from the deposits and the widely spaced geochemical sampling throughout the rest of the belt. The result of this study’s well constrained sampling through the five transects, outlined in Chapter 2, will allow the results of regional and deposit geochemical sampling to be placed in a better context. Deriving a chemostratigraphic framework will aid in the understanding of the geochemical evolution of the Hope Bay Greenstone Belt. The correct geochemical characterization of rock groups will then allow a petrologic model of the belt to be created. Geochemical characterization of mafic volcanic rocks is particularly important since the three gold deposits in the Hope Bay Greenstone Belt are hosted in mafic volcanic rocks. Locally, a connection between basalts enriched in Ti and gold deposits has long been known in the Hope Bay Greenstone Belt (eg., Sherlock et al. 2002) but the hypothesis has not been tested on a regional scale. The regional distribution of these basalts enriched in Ti thus has geodynamic and economic implications. A lithogeochemical study was undertaken to characterize the lithologic units within the Hope Bay Greenstone Belt. Samples were collected from a wide range of rock types including intrusive and extrusive rocks with compositions ranging from ultramafic to felsic. At least two samples were collected from each stratigraphic suite in the study area; in many cases in excess of four samples were taken. All rocks in the study area have been metamorphosed to various degrees with the majority metamorphosed to low greenschist grade. Areas of low strain were preferentially sampled and primary volcanic  89  features, such as pillows or volcanic clasts, were usually visible. Localized high strain (shear zones) and hydrothermal alteration (carbonitization, sericitization, albitisation, silicification) were avoided. Sampling of felsic rocks included coherent flow and pyroclastic material although, in some cases, resedimented syn-eruptive volcaniclastic material was sampled and is believed to closely represent volcanic chemistry. Mafic volcanic rock samples were taken from the core of pillows avoiding pillow selvages and pillow breccias due to their susceptibility to alteration. Some areas of alteration are impossible to avoid, in particular rocks of the Discovery Basalt Suite or Patch Basalt Suite as these lithologic units are preferentially pervasively hydrothermally altered. To minimize effects of metamorphism and alteration immobile elements, identified in other studies, will be relied upon to compare rock groups. Condie (1976) identified a number of elements as not being affected by seafloor alteration and low grade metamorphism; these elements include Ti, Y, Zr, Zn, Cr, V, Sr, Sc, Hf, Co, Nb, Ni and REE’s. These are the elements that will be focused on in the geochemical discrimination in this chapter. 3.2 Lithogeochemistry 3.2.1 Analytical Methods A total of one hundred and five lithogeochemical samples were taken in the field and sent directly to ALS Chemex in North Vancouver. Samples were crushed and pulverized using carbon steel to a size of better than 95% of less than 106 micron in size. Major elements were determined by X-ray fluorescence (XRF) and L.O.I. was determined by weight loss during the fusion of the disk. An additional 38 elements were determined using Inductively Coupled Plasma - Mass Spectroscopy (ICP - MS) using a lithium metaborate fused disk. Additional geochemical and isotopic characterisation of some of  90  the original lithogeochemical samples is presented in section 3.3. In addition to field screen, discussed above, these samples were geochemical screened to determine the lowest degrees of alteration. These ‘least altered’ samples were selected to represent each volcanic suite encountered. In addition to ALS Chemex quality controls, which were within acceptable values, internal standards were included with the sample shipments and the results are presented in Appendix C. In addition to quality control conducted at ALS Chemex, a subset of samples, mentioned above, was analyzed at the Pacific Center for Isotopic and Geochemical Research (PCIGR), the results of this along with a discussion can be found in Appendix C.  3.2.2 General Chemical Classification The rocks in the Hope Bay Greenstone Belt range in composition from rhyolite to basalt based on Zr/TiO2 vs SiO2 (Winchester, 1977) and total alkali’s vs silica (TAS) (Le Bas et al., 1986) (Figure 3.1a 3.1b). A SiO2 histogram of the samples collected in this study shows three peaks at 47, 68 and 79. These peaks correspond to the mafic volcanic rocks and two groups of felsic volcanic rocks (Figure 3.2a). After MacLean and Barrett (1993) the rocks of the Hope Bay Greenstone Belt are tholeiitic, transitional or calcalkaline. The mafic volcanic rocks have principally tholeiitic compositions with three samples in the transitional field. The felsic rocks form two groups, with most of the samples being of calc-alkaline affinity and a number of samples with very high Zr values falling into the tholeiitic field (Figure 3.2b).  91  3.2.3 Mafic Volcanic Rocks Mafic volcanic rocks of the Hope Bay Greenstone Belt make up the majority of lithologies (n=66). The SiO2 content ranges from 39 to 57% with a median of 47% SiO2. Textural examination of the two outliers with >54% SiO2 shows that they have undergone silicification. The mafic rock types in the Hope Bay Greenstone Belt are difficult to identify using IUGS classification as it is based on major elements such as Fe, Mg, K, Ca, Si which can be mobile during alteration and metamorphism (Condie, 1976; Kerrich and Wyman, 1996). These elements have seen varying degrees of mobility, depending on type and extent of alteration, but due to precautions mentioned above many samples are believed to be fairly representative of the original composition. A relatively rare feature observed in the Hope Bay Greenstone Belt is the titanium enrichment trends in the mafic volcanic rocks. In a Al2O3 vs TiO2 plot, three trends could be identified corresponding to the normal/LREE-enriched basalt group and the Ti-enriched basalt group, the Ti-enriched Al-depleted basalt group (Figure 3.3a). These groups are evident in a series of major element plots (Figure 3.4). A classification scheme that was developed for unaltered Archean rocks of the Abitibi Greenstone Belt is the modified AFM diagram (Jensen, 1976; Grunsky at al., 1992). Least altered rocks from this study area plot as andesites, normal basalts and Fe basalts in this modified AFM diagram (Figure 3.3b). These groups can be further subdivided using REE chemistry to define the normal basalt and LREE-enriched basalt groups (see below). On the basis of the discrimination tools discussed above to filter the geochemical data from mafic rocks, we can assign a proper rock name (Figure 3.5). The  92  rock names are the normal basalt, LREE-enriched basalt, Fe-,Ti-enriched basalt, Fe- and Ti-enriched Al-depleted basalt groups. Titanium concentrations of these rocks are easily observed on a TiO2 histogram where the basalts show a bimodal distribution with peaks at 1% and 1.6% TiO2 corresponding to the median of the normal-LREE-enriched basalt group and Ti-enriched basalt group (Figure 3.6a). 3.2.3.1 Normal Basalt Group The normal basalt group is the most abundant basalt group in the Hope Bay Greenstone Belt and is represented throughout the stratigraphy. This group (n=36) is characterized by TiO2= 0.39-1.12%, Al3O2/TiO2= 16.55 (Figure 3.3a). It also has a Y/Zr ratio that falls in the tholeiitic field of MacLean and Barrett (1993). A selection of other element ratios, presented on Table 3.1, shows the chemical characteristics of this normal basalt group. The subset of samples from this study has values that are typical of the larger dataset from the entire Hope Bay Greenstone Belt (Miramar Geochemical Database, 2007) (Figure 3.4and 3.7). REE from the normal basalt group have flat patterns with [La/Yb]N= 1.03, [La/Sm]N= 0.94 and [Gb/Yb]N= 1.02 and lack a Eu anomaly (Eu/Eu*=1.01) (Figure 3.8a). On a number of tectonic discrimination diagrams, the normal basalt group plot within the fields of ocean floor - calc-alkaline – volcanic arc (Figure 3.9a), island arc tholeiite – MORB – calc-alkaline (Figure 3.9b) or MORB – volcanic arc (Figure 3.10). 3.2.3.2 Light Rare Earth (LREE) Enriched Basalt Group Based on their rare earth element patterns, a group of basalts with similar Al2O3 vs TiO2 ratios to the normal basalt group can be identified and is named the Light Rare Earth Enriched (LREE) basalt group (Figure 3.8). The LREE-enriched basalt group is  93  found in a number of locations throughout the belt and is believed to be restricted to the middle to upper stratigraphic positions. The LREE-enriched basalt group is almost identical to normal group in major element chemistry such as TiO2 = 0.95% and Al2O3/TiO2 = 18.18. It differs from the normal group by enrichment in the light REE’s, Th, Zr and Nb and depletion in V and minor depletion in Fe2O3 (Figure 3.7 and 3.4). The LREE-enriched basalt group has a steeper sloped REE profile than the normal basalt group with chondrite normalized values of 14 to 55 times and ratios of [La/Yb]N= 3.91, [La/Sm]N= 2.21 and [Gb/Yb]N= 1.14, and has a moderate negative Eu anomaly (Eu/Eu*=0.69) (Figure 3.8b). The LREE-enriched basalt group plots as calc-alkaline basalts (Figure 3.9) or within plate basalts (Figure 3.10) on tectonic discrimination diagrams. 3.2.3.3 Ti-enriched Basalt Group The Ti-enriched basalt group (n=21) is known in five localities in the Hope Bay Greenstone Belt where they are named the Boston Basalt, Kennet Tarn, Patch, Doris, Boston and Bend basalt suites and are restricted to the lower portion of the stratigraphy of the belt. This group is characterized by higher TiO2 (1.22-1.91%) and low Al2O3/TiO2 (6.05-11.48). In addition to being enriched in Ti relative to normal basalts, this group is enriched in other incompatible elements such as Zr, Th, Nb and the REE’s (Figure 3.7 and 3.4). The Ti-enriched group exhibits some complicated behavior of Y and V. For example, the Doris basalt suite is depleted in V and has extreme enrichment in Y compared to the other suites in the Ti-enriched basalt group (Figure 3.7). The Ti-enriched basalt group has a flat REE profile that is approximately 20 times chondrites (Figure 3.8c) with [La/Yb]N= 1.33, [La/Sm]N= 1.06 and [Gb/Yb]N= 1.11 and  94  slight Eu anomaly (Eu/Eu*=0.96). The tectonic discrimination diagrams show a signature of ocean floor - calc-alkaline – volcanic arc (Figure 3.9a) or MORB (Figure 3.9b and Figure 3.10). 3.2.3.4 Ti-enriched Al-depleted Basalt Group The Ti-enriched Al-depleted basalt group is only found in the central and north part of the Hope Bay Greenstone Belt where they are part of the Patch Basalt Suite. This group is identifiable in the large Miramar database and is observed in this study by two samples. This group of basalts are discussed in greater detail in a thesis on the Naartok Deposit by Therriault (2006). One of these samples has MgO contents of close to 18% which is in the range of a komatiite. Volcanic textures consistent with komatiitic lavas are also observed (Therriault, 2006), but REE profiles as well as other trace elements are not constant with komatiites. The extremely high MgO contents observed are likely a result of an olivine cumulate within the basalt flow. This group (n=2) is characterized by high to extremely high TiO2 content (2.22 - 3.45%) and has varying degrees of Aldepletion. This gives an extremely low Al2O3/TiO2 ratio’s (3.07-3.85) (Figure 3.3). In addition to being enriched in Ti, relative to normal basalts, this group is enriched in many incompatible elements including Zr, Y, Nb and LREE’s. There are also notable enrichments in Cr, Ni, Fe and V, with samples showing extreme enrichments in Ni and Cr. The rocks are enriched in LREE’s and depleted in HREE which gives them a steep slope ranging from 13 to 70 times chondrites (Figure 3.8d). It has chondrite normalized ratios of [La/Yb]N= 4.80, [La/Sm]N= 1.54 and [Gb/Yb]N= 2.36 and moderate Eu anomaly (Eu/Eu*=0.46). The Ti-enriched Al-depleted basalt group plots as within plate basalts (Figure 3.9a and Figure 3.10) or above MORB (Figure 3.9b).  95  3.2.4 Felsic Volcanic Rocks The stratigraphy framework outlined in Chapter 2 will be used as a guide when discussing the felsic geochemistry. The rocks are divided into five suites; Flake Lake (2716 Ma and 2697 Ma), Square Lake (2690 Ma), Windy Lake (2686 Ma), Koignuk River (2677 Ma) and Clover Lake (2663 Ma), based on geochronology, geographic location and field relationships. The felsic volcanic rocks (n=32) have SiO2 contents that range from 55 to 78.3% with an average of 66% SiO2. Almost all of the samples with <62% SiO2 have been identified as having a significant component of physical reworking and the samples >62% SiO2 better represent primary volcanic chemistry. Based on chemistry the felsic volcanic rocks are not as easily subdivided as the mafic volcanic rocks but two main groups are observed. The first felsic group is referred to as the calcalkaline felsic group and includes the Square Lake, Windy Lake, Koignuk River and Clover Lake suites (Figure 3.2b). The second group is the tholeiitic felsic group and is made up of the Flake Lake Suite (Figure 3.2b). 3.2.4.1 Flake Lake Suite The Flake Lake Suite is the oldest episode of felsic volcanism in the belt (2697.6 to 2716 Ma) and has a unique chemical signature. This suite is set apart from the other felsic suites by an extremely high concentration of incompatible elements Zr, Y, Th, Hf and REE’s as well as low Al content (Figure 3.11). A selection of other element ratios is presented on Table 3.2 which shows the chemical characteristics of this suite. Rhyolites of Flake Lake Felsic Suite are of tholeiitic affinity using the Zr vs Y plot after MacLean and Barrett (1993) (Figure 3.1b). The REE patterns are relatively flat with minor LREE  96  enrichment; these rocks are the most REE enriched in the Hope Bay Greenstone Belt, at approximately >100 time chondrite with [La/Yb]N= 1.9, [La/Sm]N= 1.86 and [Gb/Yb]N= 0.87 (Figure 3.12a). This suite has a very pronounced negative Eu anomaly (Eu/Eu*= 0.55), likely due to Eu substituting into plagioclase (Weill and Drake 1973). There are two groups within the Flake Lake Suite that can be identified based on REE profiles. One group contains most of the samples showing a lower enrichment in REE’s whereas three samples have sub parallel and significantly more enriched profiles (Figure 3.12a). These two groups do not correspond to any spatial or temporal relationships and most likely represent differing mineralogy. Identified by Hebel (1999), this tholeiitic rhyolite was the first of its type identified in the Slave Province. According to the classification of Lesher et al. (1986) Flake Lake Suite would be called a FIIIa rhyolite (Figure 3.13). In the Superior Province, rhyolites with this unique chemistry are intimately associated with volcanic hosted massive sulfides deposits such as Noranda and Kidd creek (Bleeker et al., 1999). 3.2.4.2 ca. 2690 Ma Dacite These samples are part of a heterogeneous package of felsic volcanic rocks that is found intercalated with the Wolverine Basalts. Three samples taking suggest an age similar to that of the Square Lake Suite (2690 Ma) which is ~20 km south of the location that these samples were taken. These samples plot as calc-alkaline dacites and have similar compositions as the Windy Lake and Koignuk Suites (Figure 3.1 & 3.11). The chondrite normalized REE profiles are relatively depleted compared with other dacites, with a moderately slope with [La/Yb]N= 8.46, [La/Sm]N= 2.63 and [Gb/Yb]N= 2.38 and has positive Eu anomaly (Eu/Eu*= 1.13) (Figure3.12b REE diagrams). The samples  97  from this study are comparable to the type Square Lake section but have 5 times lower chondrite normalized REE values in the LREE. The samples collected in this study were deposited in a submarine environment and are interpreted at being resedimented syneruptive volcaniclastic deposits. 3.2.4.3 Windy Lake Suite The Windy Lake Suite extends along the entire 82 km length of the Hope Bay Greenstone Belt. It has coherent volcanic, volcaniclastic and sedimentary facies rocks. The samples analyzed as part of this study are calc-alkaline dacites with average SiO2 = 66% and Zr/Y =15.72 (MacLean and Barret, 1993). The chondrite normalized REE profiles show moderate fractionation with a slope [La/Yb]N= 16.47. A moderate enrichment in the LREE [La/Sm]N= 3.96 and [Gb/Yb]N= 2.64 and a minor negative Eu anomaly (Eu/Eu*= 0.87) is also observed in this suite (Figure3.12c). A group of three samples of the Windy Lake Suite located on the Doris Discovery Transect has more fractionated REE profiles [La/Yb]N= 25.6. These samples indicate that the Windy Lake Felsic Suite may have had a number of volcanic centers that taped a variety of magma sources. Hebel (1999) identified two groups in the Windy Lake Suite, the first (FG-1) is a dacite with a composition similar to other calc-alkaline felsic suites in the belt with SiO2 = 69% and TiO2= 0.53% and moderately fractionated REE’s. The second group (FG-2) is a calc-alkaline rhyolite which is set apart by high SiO2 (=79%) and low TiO2 (=0.11%), a large enrichment in the LREE’s [La/Yb]N = 71.2, HREE enrichment ([La/Sm]N = 6.0, and [Gd/Yb]N = 5.0, and a minor negative Eu anomaly (Eu/Eu* = 0.9). The rhyolite (FG-2) group of the Windy Lake Suite was not observed in the course of mapping and is confined to a 2.5 km by 500 m locality in the middle of the belt. This  98  group is not representative of the Windy Lake Suite with dacite (FG-1) comprising over >90% of this suite. 3.2.4.4 Koignuk Suite The Koignuk Suite (2677 Ma) is the second of the two regionally extensive felsic volcanic units and is found along the western side of the Hope Bay Greenstone Belt. This suite has an average SiO2 content of 67% and a Zr/Y= 12.2, consistent with a calcalkaline dacite composition (MacLean and Barret, 1993). The compositions of these rocks are homogenous throughout the entire 40 km length of the belt. Chemical compositions of this suite are similar to the Windy Lake Suite, but the average compositions of the Koignuk suite have more Fe, V and Ti (Figure 3.11). The chondrite normalized REE profiles show a moderate amount of fractionation [La/Yb]N= 11.34 , with moderate enrichment in the LREE [La/Sm]N= 3.85 and [Gb/Yb]N= 2.05 and has a minor negative Eu anomaly (Eu/Eu*= 0.92) (Figure 3.12d). The REE profiles from the Koignuk Suite are less fractionated than the Windy Lake Suite. 3.2.4.5 Clover Lake Suite Three small outcrops in the middle of the Clover Valley comprise the Clover Lake Suite. As the youngest volcanic rocks identified in the belt (2663 Ma; Hebel, 1999), it has a distinctive chemical signature. This suite is characterized by extremely high SiO2 (75%) and a Zr/Y=16.6, indicating a calc-alkaline rhyolite. This rhyolite differs from all other felsic volcanic suites in the Hope Bay Greenstone Belt by having a steep REE profile and, except for Rb, is extremely depleted in all trace elements (Figure 3.11 and Figure 3.12e). The chondrite normalized REE profiles show a very high degree  99  of fractionation [La/Yb]N= 36.34, with moderate enrichment in the LREE [La/Sm]N= 4.45 and [Gb/Yb]N= 4.85 and has a large Eu anomaly (Eu/Eu*= 0.45). 3.2.4.6 Clover Epiclastics A final group of felsic volcanic rocks identified is called the Clover epiclastics. These rocks occur in the same geographical area as the Clover Lake Felsic Suite. The volcanic textures are not particularly clear but this deposit is interpreted as a secondary volcanic deposit, meaning that the original magma composition is not preserved. This group of rocks contains relatively high concentrations of compatible elements such as V, Fe and Ti, but generally low concentrations of incompatible elements (Figure 3.11). The REE profiles have a moderate slope [La/Yb]N=5.61 with some enrichment in the LREE [La/Sm]N=2.82 no enrichment in the HREE [Gd/Yb]N=1.62 and no europium anomaly (Eu/Eu*=1.00) (Figure 3.12f).  3.2.5 Chemostratigraphic Columns The geochemical results can be integrated with the structural-stratigraphic columns, from Chapter 2, to examine the geochemical evolution of the Hope Bay Greenstone Belt. This time horizon of 2686 Ma is the first time that belt wide felsic volcanism is observed and is a logical location to break the belt into two domains. This age of 2686 Ma represents the transition period in the belts history where mafic dominated volcanism is replaced by interbedded felsic and mafic volcanism with lesser sedimentation. Cycles of volcanism (mafic and felsic) are often difficult to subdivide as stratigraphic columns are not continuous. This is problematic in the south part of the belt  100  because the structural-stratigraphic columns are not continuous and there may be pieces of belt stratigraphy missing. In the south part of the belt, the volcanic packages have a pattern of alternating mafic – felsic volcanism capped by sedimentary rocks (Figure 3.14). The older domain in the south part of the Hope Bay Greenstone Belt contains intercalated normal tholeiites, Ti-enriched tholeiites and tholeiitic rhyolites. In this study only the Ti-enriched tholeiites and tholeiitic rhyolites were encountered but the Bend Basalt Suite contains intercalated Ti-enriched and normal basalts. The area around Flake Lake is the only location where this complicated mixture of tholeiitic rhyolites, Tienriched basalts and normal basalts are seen and is a good example of bimodal volcanism. The volcanism in the lower domain basalts are likely plume dominated. The source of the tholeiitic rhyolites may be in a back arc setting and is elaborated on in the discussion. In the south part of the belt the younger domain (<2686 Ma) is made up of normal basalts, LREE-enriched basalts and calc-alkaline dacites are observed. This sequence is capped by the Clover Lake Sedimentary Suite and a calc-alkaline Clover Lake rhyolite. There are two sequences of calc-alkaline dacites (Windy Lake Felsic and Koignuk Suites) overlain by mafic volcanic suites (Member Basalt and Clover West Basalt Suites) in this domain. The stratigraphic repetition of these sequences that have similar chemistry and magma sources shows that there were multiple cycles of mafic and felsic volcanism in the south part of the belt. The north part of the belt has a relatively continuous stratigraphic record (Figure 3.15). Similar to the south part of the stratigraphy there are two domains based on the time horizon of 2686 Ma. The older domain is composed almost entirely of a number of  101  Ti-enriched basalt – normal basalt cycles. The base of the stratigraphy in the north part of the belt contains Ti-enriched basalts of the Doris Group with is overlain by a normal basalt suite overlain by the Patch Basalt Suite where Ti-enriched basalt and Ti-enriched Al-depleted basalt groups are found together. The trace element compositions of the two suites of basalt enriched in titanium vary. The Doris Group is depleted in V and enriched in Y and Zr compared all the other titanium basalt suites. The upper parts of the stratigraphy of the older domain are dominated by normal basalts with minor intervals of Ti-enriched basalts at the top of the older domain. This continuous succession of basalt stratigraphy shows that there were multiple cycles of Ti-enriched basaltic separated by normal basaltic volcanism. The younger domain (<2686 Ma) in the north part of the belt is made up of calcalkaline, normal basalts and LREE-enriched basalts. The two calc-alkaline felsic suites (the Windy Lake and Koignuk Suites) have similar major and trace element compositions and are separated by basalts that have normal and LREE-enriched chemical signatures. Local Ti-enriched basalts are also found outside the transect area. The upper limit of the Windy Lake Felsic Suite sedimentation is 2678 Ma which means that the basalts overlying it are coeval with the Koignuk Felsic Suite. Above these volcanics is the Conglomerate Hill Sedimentary Suite (2670 Ma) which contains argillites and conglomerates. These are intruded by sills of the late mafic intrusions which are a xenolith rich suite. The north and south parts of the belt are comparable in stratigraphic succession (Chapter 2) as well as geochemical evolution. In older domain (>2686 Ma) the normal and Ti-enriched groups can be correlated across the entire belt while Ti-enriched Al-  102  depleted basalt group is restricted to the north part of the belt and the tholeiitic rhyolite, of the Flake Lake Suite, is restricted the south part of the belt. Chemical groups of the younger domain (<2686 Ma) can be correlated across the belt. In both parts of the belt calc-alkaline Koignuk and Windy Lake Felsic Suites are separated by mafic volcanism. Both of these felsic suites are local associated with LREE-enriched basalts which could be the result of mixing. The northern and southern parts or the Hope Bay Greenstone Belt have similar geochemical signatures and can be successfully correlated. 3.3 Isotope and High Resolution Trace Element Geochemistry (PCIGR) High-resolution trace element and Hf-Nd isotopic compositions of 35 samples were measured at the Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia. The samples are a subset of the larger dataset and are representative samples from the mafic and felsic volcanic suites and were selected avoiding alteration. The procedures of sample preparation, dissolution, column chemistry and analysis are presented in Appendix B.  3.3.1 Results of Lu-Hf and Sm-Nd Geochemistry The analytical results and other calculated data such as initial ratios at the time of emplacement and epsilon values for samples are presented in Table 3.3. Rock suites identified previously will be referred to in the discussion of various binary plots and histograms showing distribution of model ages.  147  Sm/144Nd vs 143Nd/144Nd plot shows  three main groups; the normal and Ti-enriched basalt groups which has higher 143  Nd/144Nd and 147Sm/144Nd ratios, the calc-alkaline felsic, LREE-enriched enriched  basalt and Ti-enriched Al-depleted basalt groups which have much lower ratios and the  103  group of samples the tholeiitic rhyolite group (Figure 3.16). The third group, the tholeiitic rhyolites of the Flake Lake Suite plots between the other two main groups and also shows a distribution disturbance around the isochron line. A plot of 176Lu/177Hf vs 176Hf/177Hf shows a similar grouping of samples as observed in the Sm-Nd plot. Calc-alkaline felsic and Ti-enriched Al-depleted basalt group have lower 176Hf/177Hf and 176Lu/177Hf ratios whereas the normal and Ti-enriched basalts have higher ratios (Figure 3.17). Ideally all the samples that have been part of a closed isotopic system should fall on a line (isochron) on the Sm-Nd and Lu-Hf isochron. Samples that do not fall on, or close to, the isochron may be explained by either analytical problems, inhomogeneities of the sample or the isotopic system may have been disturbed by alteration. This problem is not seen in the Sm-Nd samples as the results are within an acceptable range on the isochron diagram. The Lu-Hf results have 6 samples that exhibit abnormal behaviour. These samples are from the Flake Lake Suite, the Windy Basalts, Member Basalts and Wolverine Basalts (Figure 3.17). These samples are labeled the “isotopically disturbed group” and will be excluded from further discussion as they likely represent an open system and do not represent primary isotopic compositions. Alteration in all the samples and the disturbed group will be examined in closer detail in the next section (3.3.2 Alteration and Isotopic Disequilibrium). Examining the initial ratio of 143Nd/144Nd and 176Hf/177Hf at 2.68Ga, (143Nd/144Nd)@2.68Ga vs. (176Hf/177Hf)@2.68Ga , samples from the Hope Bay Greenstone Belt shows the presence of distinct groups. The calc-alkaline felsic rocks overlap with the Tienriched basalt group whereas the normal basalt group has lower (143Nd/144Nd)@2.68Ga values and the isotopically disturbed group have low (176Hf/177Hf)@2.68Ga values (Figure  104  3.18). The tholeiitic rhyolite group (Flake Lake Suite) has a wide range of (143Nd/144Nd)@2.68Ga , from 0.50906 to 0.50947, as well as a large range of (176Hf/177Hf)@2.68Ga values, from 0.28107 to 0.28206. The Ti-enriched Al-depleted basalt group has similar (143Nd/144Nd)@2.68Ga values to the calc-alkaline group but with lower (176Hf/177Hf)@2.68Ga . The LREE-enriched basalt sample plots similarly to the calcalkaline felsic groups. In the previous section (3.2.3) four basalt groups were determined using a number of discrimination diagrams, these groups are called Normal basalt, LREE-enriched Basalt, Ti-enriched Basalt and Ti-enriched Al-depleted basalt groups. A plot of Al3O2/TiO2 vs. İNd(i) (Figure 3.19) shows that the normal basalt group range in İNd value from 2.1 to 5.5, the Ti-enriched basalt group have a similar range of İNd(i) 1.7 to 4.6 and the Ti-enriched Al-depleted basalt group has values of 3.8 and 3.6. These samples have no overall correlation between İNd(i) and Ti-enrichment. Examining the Al3O2/TiO2 vs. İHf(i) plot, the normal basalt group has a large range in İHf(i) values (Figure 3.20). The normal basalt group ranges from -12.8 to 4.4 and has 6 samples with values of İHf <-2, which have been identified as being isotopically disturbed. The Ti-enriched basalt group has a range in İHf(i) values from -1.6 to 4.6 and the Ti-enriched Al-depleted basalt group has İHf(i) values of 4.4 and 3.4. 3.3.1.1 Model Ages It is assumed that the Earth’s crust has been created from the mantle by magmatism. When the first piece of the crust was created, it had the 143Nd/144Nd or 176  Lu/177Hf ratio of the mantle. The assumption can be made that the mantle has the same  Nd and Hf isotopic history as Chondritic Uniform Reservoir (CHUR) or Depleted Mantle  105  (DM). This means a piece of crust will have the same 143Nd/144Nd or 176Hf/177Hf as the mantle when it is created. If we know the present day Sm/Nd and 143Nd/144Nd ratio or Lu/Hf and 176Hf/177Hf ratio of a rock, we can calculate Hf and Nd model ages. The point at which the line describing the evolution of the sample intersects the line describing the evolution of DM or CHUR gives the model age, IJDM or IJCHUR (Figure 3.21). The model ages calculated for Nd and Hf relative to both CHUR and DM (Table 3.3). The IJCHUR for Nd (NdIJCHUR) yielded 11 meaningless ages (negative). Examining (143Nd/144Nd)@2.68Ga vs NdIJCHUR the normal basalt group has ages of less than 1.5 Ga whereas the majority of the samples plot between 2 and 3 Ga (Figure 3.22). The calcalkaline felsic group has very homogenous values with an average NdIJCHUR of 2.47 Ga. The Ti-enriched basalt group has an average NdIJCHUR of 2.25 Ga whereas the normal basalt group has an average NdIJCHUR of 1.25Ga. The model ages for NdIJCHUR have a weakly bimodal distribution with peaks at 2.15Ga and 2.55Ga (Figure 3.23). The group at 2.15Ga is dominated by basalts while the group at 2.55Ga is made up of felsic volcanic rocks. Examining the (143Nd/144Nd)@2.68Ga vs NdIJDM diagram, a number of overlapping groups can be identified (Figure 3.24). The Normal basalt group has a range of model ages from 2.25 to 3 Ga with an average of 2.68Ga and the Ti-enriched basalt group ranges in model ages from 2.5 to 3.25Ga with an average of 2.9Ga. The calc-alkaline felsic group is very homogenous with Koignuk Felsic Suite and Windy Felsic Suite having an average NdIJDM of 2.78 and 2.9Ga respectively. The tholeiitic felsic group (the Flake Lake Felsic Suite) has a wide range of model ages and (143Nd/144Nd)@2.68Ga values with an average NdIJDM of 3.16Ga. The model ages for NdIJDM show a normal distribution  106  with a median of 2.75Ga (Figure 3.25). The calc-alkaline felsic group is older than the U/Pb ages of the rocks whereas the rest of the groups overlap the U/Pb ages. The IJCHUR for Hf (HfIJCHUR) yielded 6 ages that were meaningless as they were zero or negative. The plot of (176Hf/177Hf)@2.68Ga vs HfIJCHUR shows the normal basalt group has a wide range of model ages with an average HfIJCHUR of 2.0Ga and the Ti-enriched basalt group having a average HfIJCHUR of 2.64Ga (Figure 3.26). The calc-alkaline felsic group has a tight range of model ages with an average HfIJCHUR of 2.45Ga whereas the tholeiitic felsic group has a moderate range of model ages with an average HfIJCHUR of 2.18Ga. On the histogram, the HfIJCHUR has a poorly defined bimodal distribution with peaks at 2.1 and 2.55Ga (Figure 3.27). The basalt groups are distributed across the histogram while the calc-alkaline felsic group makes up the majority of the peak at 2.55Ga. The (176Hf/177Hf)@2.68Ga vs HfIJDM has the majority of model ages between 2 and 3Ga with all the groups having a great deal of overlap (Figure 3.28). The normal basalt group has an average HfIJDM of 3.17Ga and the Ti-enriched basalt group has an average Hf  IJDM of 3.6Ga. The felsic rocks have an extremely homogenous Hf model ages (avg  Hf  IJDM = 2.47Ga) and the tholeiitic felsic group and an average HfIJDM of 1.86Ga.  Examining the histogram the HfIJDM have a bimodal distribution with peaks at 2.1 and 2.55Ga (Figure 3.29). The basalts make up the majority of the peak at 2.1Ga whereas the peak at 2.55Ga is made up of both basalts and felsic volcanic rocks. The initial İNd(i) vs İHf(i) plot has three main groups, the disturbed group of samples with unrealistically low ratios of Hf, the tholeiitic felsic group and the main cluster of samples (Figure 3.30). Within the main group, the Normal and LREE-enriched basalt groups have higher İNd(i) values (avg = 3.7) and slightly lower İHf(i) values (avg =  107  2.1). Also in the main group, the Ti-enriched basalt group has average İNd(i) = 3.2 and İHf(i) = 2.8 and Ti-enriched Al-depleted basalt group has average İNd(i) = 3.7 and İHf(i) = 3.9. The calc-alkaline felsic group has an average İHf(i) = 4.5 and İNd(i) = 2.7. The tholeiitic felsic group has a large range of values of İNd(i) = -1.9- 6.0 and İHf(i) = -0.1 - 35.3 with no clear isotopic signature.  3.3.2 Alteration and Isotopic Disequilibrium The group identified as being isotopically disturbed needs to be examined in further detail to determine the reason for its abnormal behaviour. Element molar ratios can be useful when examining hydrothermal alteration to albite or sericite. An increase in the molar ratio of K to Al can indicate alteration to sericite, KAl3Si3O10(OH)2 , whereas an increase in the ratio of Na to Al can indicate alteration to albite, NaAlSi3O8 (S. Halley, pers comm., 2007). The least altered samples will have very low <0.03 K/Al molar ratios and between 0.2 and 0.4 Na/Al molar ratios. Three of the six samples identified as being in isotopic disequilibria have experienced low degrees of sericite alteration (Figure 3.31). In the Hope Bay Greenstone Belt, the Hf isotopic system was identified as being more affected by the disturbance than the Nd system. Loss on Ignition (LOI) is commonly a good proxy for hydrothermal alteration as many primary silicates are hydrated and CO2 is added. Examining the İHf vs LOI diagrams, the isotopically disturbed group of samples are identified by their extremely low İHf values but have a wide range of LOI. In the isotopically disturbed group of samples, there is no correlation between LOI and İHf value (Figure 3.32).  108  The mineral systematics of the Hf system are not completely understood and the low grade alteration/metamorphism of minerals to epidote and chlorite seem to affect the closure of the Hf isotopes (D. Weis, pers comm., 2007). The background greenschist metamorphism produces abundant chlorite and epidote in the Hope Bay Greenstone Belt and may be responsible for the disturbance in the Hf system (Gebert, 1991). A number of thin sections of the isotopically disturbed samples were compared to that of other basalts that were not disturbed and the mineralogy was relatively similar with all samples containing chlorite ±epidote. A detailed study of alteration and metamorphism is beyond the scope of this study and these 6 basalts that appear isotopically disturbed will be excluded from the final discussion.  3.3.3 Isotopic Sources of the Hope Bay Greenstone Belt The Sm-Nd and Lu-Hf isotopes in the Hope Bay Greenstone Belt as petrogenetic tracers have been useful in fingerprinting the volcanic groups. (Figure 3.16 and 3.17). Both plots show the Ti-enriched basalt and the normal basalt groups have isotopic compositions close to today’s depleted mantle and bulk silicate earth. Samples from the calc-alkaline group have the lowest radiogenic ratio and plot lowest on the graph with the LREE-enriched basalt and Ti-enriched Al-depleted basalt group having intermediate ratios (Figure 3.16 and 3.17). The tholeiitic felsic group has isotopic compositions between the two clusters described above but many of the tholeiitic felsic group samples do not fall on the 2.68Ga isochron which indicates that these samples exhibit odd systematics.  109  (143Nd/144Nd)@2.68Ga vs (176Hf/177Hf)@2.68Ga has no clear trend for Hf isotopes but the Nd isotopes show groupings of rock types. The normal basalt group has higher (143Nd/144Nd)@2.68Ga ratios whereas the calc-alkaline felsic and Ti-enriched basalt groups have lower ratios. The Ti-enriched Al-depleted basalt group lies between the two areas (Figure 3.33). The fact that no pattern exists in the (176Hf/177Hf)@2.68Ga, indicates that Nd and Hf isotopes were not behaving the same in the system. There are no clear trends for the İNd(i) and İHf(i) vs Al2O3/TiO2 (Figure 3.19 and 3.20). In these plots, there is a large variation in the Al2O3/TiO2 ratios but there is no correlation with the Nd or Hf isotopic composition (Figure 3.34). Samples from the Tienriched Al-depleted basalt group and the Ti-enriched basalt groups appear to have more homogenous Hf isotopic compositions than the normal group(Figure 3.34). The NdIJDM of samples from the Hope Bay Greenstone Belt, indicate that the crystallization of the rock occurred between 2.8 and 2.9Ga. This differs from the NdIJCHUR peaks which are at 2.1 to 2.2Ga for the normal basalt group and 2.5 to 2.6 for the calcalkaline felsic group. From U/Pb dating of zircons, the age range of magmatism is from 2716 to 2662 Ma, and overall the NdIJDM is a good estimate of the time at which the magma that created these rocks was extracted from the mantle. Examining only the calcalkaline felsic group the NdIJCHUR is a good approximation of the model age. Hf  IJ of from the Hope Bay Greenstone Belt have mixed results as expected from  their disturbed systematics, with only the calc-alkaline felsic samples coming close to the accurate U/Pb ages. Examining the Hf model ages, both the HfIJDM and HfIJCHUR do not give ages close to the known time of crystallization. The basalt groups have very young  110  model ages and the calc-alkaline felsic group gives a better approximation of the age as they overlap the U/Pb ages. Overall the NdIJDM appears to give the best distribution of ages and has a peak that is close to the crystallization age of the rocks (~2.68Ga). Examining only the calcalkaline felsic group, the HfIJDM appears to be a good approximation of the age of crystallization. The İNd(i) vs İHf(i) show a weak negative correlation when the isotopically disturbed samples are removed (Figure 3.35). All the basalt groups overlap with respect to İNd(i) and İHf(i) but much of the normal basalt group appears to be İHf(i) depleted and enriched in İNd(i) compared to the other two groups. This is unusual, as these samples that have been shown to have similarities to MORB, which comes from a DM source typically has a depleted İNd(i) and depleted İHf(i) values. Vervoort and Blinchert-Toft (1999) identified that in the early Archean, the mantle had a narrow range in İHf(i) values but a very wide range in İNd(i) values, which results in a horizontal trend oblique to the juvenile array. Vervoort and Blinchert-Toft (1999) attribute the dispersion in the İNd(i) of these rocks to a later disturbance in the Sm-Nd isotope system and does not represent initial isotopic variations in the early Earth. A similar pattern of a horizontal trend oblique to the juvenile array is observed in the samples from the Hope Bay Greenstone Belt. It is not clear if the Hf or Nd isotopes are shifted away from the juvenile whole rock mantle array identified by Vervoorti and Blinchert-Toft (1999). There is a group of basalts that is isotopically disturbed in Hf which are discussed above and named the isotopically disturbed group. There is little evidence to suggest that all the rocks in the Hope Bay Greenstone Belt have experienced an isotopic disturbance in Hf. The normal  111  basalt group is the group that has the largest shift away from the juvenile whole rock mantle array. The calc-alkaline felsic group is fairly homogenous with respect to İNd(i) and is less homogenous with respect to İHf(i). The Ti-enriched Al-depleted basalt and Tienriched basalt groups have isotopic compositions that are transitional between the calcalkaline and the normal basalt group. The tholeiitic rhyolite group (the Flake Lake Felsic Suite) was omitted from much of the discussion above since it has highly variable Hf and Nd isotopic composition. The highly variable isotopic compositions observed in these rocks are consistent with highly variable trace element values (Figure 3.11).  3.4 Discussion On a regional scale, geochemical fingerprinting of the volcanic rocks has defined a number of chemically distinct suites that are restricted to particular portions of the stratigraphy. These suites appear to have slightly different sources of formation. 3.4.1 Mafic Volcanic Rocks Mafic rocks in the Hope Bay Greenstone Belt have a number of chemically distinct suites, many of which are stratigraphically restricted. These suites include the normal basalt, LREE-enriched basalt, Ti-enriched basalt and Ti-enriched Al-depleted basalt groups. The elevated Ti content of the Ti-enriched basalt and Ti-enriched Aldepleted basalt groups are not observed in any other greenstone belt in the SSP. There is only one locality with similar rocks on the continent, found in the Abitibi Greenstone Belt (Stone et al., 1987; Xie et al., 1993).  112  The normal and Ti-enriched basalts are similar to rocks erupted by decompression melting of the mantle due to their flat REE profiles however they are not N-MORB or EMORB (Hofmann, 2003). The lack of any other part of an ophiolite sequence would support the idea that these rocks are not from a mid ocean ridge setting. Since differing REE patterns Ti-enriched basalts and normal basalts likely originated from the same melting regime (decompression melting) the enrichment in incomparable elements resulted from enriched mantle being incorporated to the melt. This may infer that the mantle beneath the Hope Bay Greenstone Belt was inhomogeneous. The isotopic evidence is consistent with trace and REE patterns and shows that the Ti-enriched basalt group has an enriched source compared to the normal basalt group. The Ti-enriched Aldepleted basalt group is the result of high degrees of melting of the mantle. It has been suggested that this group is the result of a complicated interaction between plume and mantle melting, with an enriched mantle likely being involved (Therriault 2006). This idea does not fit well with the geology which suggests quick transition between some of the Ti enriched and normal basalt groups. The Ti-enriched Al-depleted basalt group has a REE signature similar to ocean island basalts (OIB); this hypothesis has limited support by the isotopic evidence, as the Ti-enriched Al-depleted basalt group has similar isotopic ratios to the calc-alkaline felsic volcanic rocks. The LREE-enriched basalt group is the rock type closest to andesites in the belt and is similar to primitive arc basalts (Kelemen et al., 2003). Examining the chemo-stratigraphic columns, we see that the Ti-enriched mafic volcanic rocks lie in the lower portions of the volcanic stratigraphy of the Hope Bay Greenstone Belt (Figure 3.14 and 3.15). Ti-enriched mafic volcanic rocks host the  113  Naartok and Doris Deposits and are locally found in the Boston Deposit. Normal basalts are found throughout the stratigraphy with the LREE-enriched group restricted to the middle and upper portions. The Ti-enriched mafic volcanic rocks (Ti-enriched Aldepleted basalt group and Ti-enriched basalt group) are highly prospective for gold mineralization and are easily identified using geochemical screening (Figure 3.5). 3.4.2 Felsic Volcanic Rocks Felsic rocks are made up of four calc-alkaline suites and one tholeiitic suite. The felsic calc-alkaline suites include the Square Lake Suite, Windy Lake Suite, Koignuk Suite and Clover Lake Suite. These four suites are formed by similar magmatic processes though they are distinct volcanic events and are separated by mafic volcanism. This group of rocks has geochemical signature similar to a volcanic arc setting (Kelemen et al., 2003). The Square Lake Suite, Windy Lake Suite and Koignuk Suite are similar and could result from dehydration of slab and hydration of the mantle similar to that we see in modern volcanic arcs (Bebout, 2003). A felsic tholeiite suite named the Flake Lake suite is of rhyolitic composition. The relatively unfractionated REE profile indicates that the garnet did not fractionate from the liquid nor was it a residual phase (Weill and Drake, 1973). The petrogenesis of this rock has not been resolved but these two scenarios may explain their compositions. The first scenario includes a primitive source mafic magma which evolved at a shallow level in the crust drawing mafic magmas out of the chamber with little crustal assimilation until rhyolite erupted. The second scenario is the partial melting of a dry mafic tholeiitic crustal source generating a rhyolitic melt, leaving a residue dominated by plagioclase and clinopyroxene (Thy et al., 1990). Tholeiitic rhyolites of the Kidd Creek  114  Assemblage in the Abitibi greenstone belt have similar chemical characteristics to the Flake Lake Felsic Suite and are intruded by gabbro sills and overlain by the basaltic volcanic rocks (Bleeker et al., 1999). One key difference between the two units is the Kidd Creek rhyolites are associated with komatiites but no true komatiites are found in the Hope Bay Greenstone Belt.  3.4.3 Correlating Geochemistry within the Hope Bay Greenstone Belt Geochemical signatures of the volcanic suites in the Hope Bay Greenstone Belt are similar in the north and south parts of the belt. Mafic volcanic rock groups dominate the stratigraphy, with normal basalt, LREE-enriched basalt and Ti-enriched basalt groups found in both the south and north parts of the belt and Ti-enriched Al-depleted basalt group restricted to a continuous stratigraphic package (the Patch Basalt Suite) in the north part of the belt. Calc-alkaline felsic packages of the Windy Felsic and Koignuk Suite are regionally continuous units found along the entire length of the belt. Chemical compositions of these units are extremely homogenous over their entire range. Restricted to the south part of the belt, the Clover Lake Suite is found in only one location whereas the tholeiitic Flake Lake Suite has a great deal of geochemical variability. Found in the middle belt with local beds in the north part of the belt, the Square Lake Suite is the oldest calc-alkaline volcanism in the Hope Bay Greenstone Belt at 2690 Ma. The Hf and Nd isotopes have proven useful in identifying the sources of magma for the rocks of the Hope Bay Greenstone Belt. Geochemical groups identifying the major and trace element analysis are confirmed by Nd and Hf isotopic composition.  115  3.4.4 Comparisons to other Greenstone Belts In the Slave Structural Province, the Yellowknife Greenstone Belt has been compared to the Hope Bay Greenstone Belt (Hebel, 1999; Sherlock et al., 2001). It has a number of similarities in age and basic geology but differs in the number of volcanic cycles and range of rock compositions. The Yellowknife Greenstone Belt does not contain rocks similar to the tholeiitic rhyolites or Ti-enriched Al-Depleted basalts (Bleeker, 1999; Cousens, 2000; Cousens et al., 2006). However, the Kam Group of the Yellowknife Greenstone Belt does locally contain some Ti-enriched basalts similar to those found in the Hope Bay Greenstone Belt (Cousens, 2000). Located in the eastern Superior Province, the Abitibi Greenstone Belt is the best documented greenstone belt in Canada. There are numerous similarities between these greenstone belts, including the presence of tholeiitic rhyolites and Ti-enriched Aldepleted basalts (Stone et al., 1987; Xie et al., 1993; Bleeker et al., 1999; Ayer et al., 1999). Differences between the two belts include the lack of large faults and komatiites in the Hope Bay Greenstone Belt (Ayer et al., 1999). The Abitibi has two main tectonic models; the “oceanic island arc subduction zone” model (Jackson and Fyon 1991; Kerrich et al., 1999; Ayer et al., 2002; Wyman et al. 2002) and the (para) autochthonous model (Thurston, 2002, Ayer et al. 2002). 3.5 Summary The combination of field relationships, from a number of discrete transects across the Hope Bay Greenstone Belt, and U-Pb geochronology has allowed the creation of a revisted stratigraphic framework (Chapter 2). This model is used as a base for lithologic  116  and isotope geochemical techniques, which characterize the volcanic suites of the Hope Bay Greenstone Belt. An examination of the lithogeochemistry and isotope geochemistry in the Hope Bay Greenstone Belt shows that mafic and felsic volcanic rocks have a range of chemical signatures. The majority of rock types in the belt are common to greenstone belts in the Canadian Shield including basalts, with lesser andesites, dacites and rhyolites. However the Hope Bay Greenstone Belt has a number of rock types that are rare or undocumented in greenstone belts. These rare rock types include the relatively minor Ti-enriched Aldepleted basalt (Patch Basalt Suite) which is part of a larger Ti enriched group and tholeiitic rhyolite groups (Flake Lake Felsic Suite). The integration of the stratigraphic framework (Chapter 2) and the geochemical results allow us to understand the chemical evolution of the belt. Many mafic volcanic groups and felsic volcanic suites are restricted to particular portions of the stratigraphy. The lower portions of the stratigraphic (>2686 Ma) contain high Ti basalt groups as well as normal basalt groups and the anomalous tholeiitic rhyolite of the Falk Lake Suite. The upper portions of the stratigraphy contain calc-alkaline dacites with minor calc-alkaline rhyolite, normal basalt and LREE basalt. The distribution of these geochemical packages has implications for the tectonic evolution of the belt as well as mineral exploration. There are important tectonomagmatic changes that occur between the deposition of the rocks in the upper and lower parts of the stratigraphy. The observations can be generalized to conclude that the rocks found in the lower part of the stratigraphy have sourced from high degrees of partial melting of the mantle possibly with the influence of a plume. The rocks that make up the upper part of the stratigraphy are a mixture of  117  primitive arc basalts and calc-alkaline rocks which are sourced from lower degrees of partial melting of crust or the mantle. From these observations it could be inferred that the Hope Bay Greenstone Belt has gone from a plume dominated setting to an island-arc setting. In addition to this, some of the basalts in the lower parts of the stratigraphy are enriched in Ti (plus a series of incompatible elements) which can be explained by the melting of an inhomogeneous mantle. The results of Sm-Nd and Lu-Hf isotopic analysis show that there are significant differences between volcanic groups. The calc-alkaline group plot in a homogenous array with some samples falling on the juvenile mantle whole rock array. The normal basalt group has some problems with isotopic disequilibrium. Nonetheless this group has a negative correlation of İHf(i) and İNd(i) values. The Ti-enriched Al-depleted basalts and Ti-enriched basalt groups have isotopic compositions that are transitional between the calc-alkaline and the normal basalt group. The association of particular lithologic suites and gold deposition in the Hope Bay Greenstone Belt suggest that fluid-rock interaction and wall rock sulphidation are the most important mechanisms for depositing gold (Mikucki, 1998). These rock groups have high Ti contents and are named the Ti-enriched basalt group and the Ti-enriched Aldepleted basalt group. These basalt groups are found in the Bend Basalt Suite and Kennet Tarn Basalt Suite which do not host gold deposits and the Boston Basalt Suite, Doris Basalt Suite and Patch Basalt Suite which each host gold deposits. All these basalt suites containing Ti-enriched basalts represent a high exploration potential.  118  Table 3.1: Average inter-Element ratios for four basalt groups from six transects of the Hope Bay Greenstone belt Ti enriched Al depleted basaltTi Basalt Group basaltic LREE normal enriched komattite Basalts Basalts Basalts (n=2) (n=6) ı (n=36) ı (n=19) ı 48.3 3.87 46.5 4.40 48.9 3.81 40.5 SiO2 17.10 1.72 14.25 1.57 13.40 1.42 10.06 Al2O3 10.80 2.33 12.35 1.70 14.45 2.91 17.28 Fe2O3 0.96 0.11 0.88 0.14 1.50 0.14 2.84 TiO2 MgO Zr Y Al3O2/TiO2 TiO2/V TiO2/Y TiO2/Zr Ti/V Nb/Yb Ce/Y Ti/Nb Zr/Y Mg# Eu/Eu* (La/Yb)N (La/Sm)N (Gd/Yb)N  ı 1.62 4.57 3.01 0.87  5.86 107.38 21.58 18.18 41.74 448.67 97.65  1.78 29.13 4.14 3.43 5.81 44.88 39.55  6.22 54.34 18.67 16.55 30.41 474.41 167.11  3.02 14.44 3.57 2.28 2.52 55.57 30.56  3.72 99.16 33.63 8.96 67.28 478.58 153.66  1.45 21.12 6.34 1.10 52.37 120.48 31.56  12.95 142.00 26.20 3.46 67.97 1079.54 197.33  6.99 25.46 7.64 0.55 1.27 17.30 25.87  145.57 2.59 1.44 3.64 5.20 51.49 0.69 3.91 2.21 1.40  17.57 0.63 0.29 0.71 1.94 7.51 0.12 0.22 0.22 0.92  198.32 1.14 0.43 1.58 2.97 50.50 1.01 1.03 0.94 1.02  16.48 0.20 0.07 0.31 0.91 7.24 0.06 0.07 0.13 0.21  124.17 1.60 0.54 2.04 3.23 33.89 0.96 1.33 1.06 1.11  52.34 1.22 0.21 0.66 1.23 7.15 0.16 0.36 0.16 0.70  88.17 9.64 1.58 4.55 5.51 56.82 0.46 4.80 1.54 2.36  1.64 0.51 0.50 0.05 0.64 10.16 0.02 0.03 0.36 1.42  119  Table 3.2: Average sellected element and inter-Element ratios for six felsic groups from six transects of the Hope Bay Greenstone belt Clover Windy Square Flake Lake Clover Koignuk Lake Lake Lake Suite Epiclastics Suite Suite Suite Suite (n=1) (n=4) ı (n=11) ı (n=9) ı (n=2) ı (n=7) ı SiO2  74.85  2.68  66.52  2.22  65.85  3.033  62.91  3.967  57.45  1.277  75.08  Al2O3  11.19  0.60  15.49  0.615  14.85  0.985  15.63  1.009  15.76  1.263  12.90  Fe2O3  4.37  2.13  2.87  0.651  3.77  1.075  5.77  1.945  7.30  0.675  0.79  TiO2  0.23  0.08  0.33  0.106  0.43  0.083  0.56  0.095  0.72  0.173  0.09  Zr  361.43  113.96  102.25  24.2  146.38  16.73  56.50  Nb  25.39  23.34  2.00  0  5.67  3.048  6.36  2.157  6.60  1.233  3.00  V  14.86  18.59  48.00  21.21  51.67  28.39  81.36  28.03  121.00  24.95  8.00  2.00 6.75 3.67 12.47 15.72 50.65 65.00 32.53 491.47 69.62 2.13 8.47 2.63 2.39 1.14  0 5.67 3.048 6.36 2.157 0.778 23.58 10.25 17.67 3.888 0.471 5.32 0.906 5.78 1.46 3.017 24.25 10.62 16.70 5.1 2.861 13.86 3.983 12.20 3.159 18.42 35.26 6.256 28.68 3.898 21.21 131.25 67.74 113.85 25.06 13.86 31.59 7.793 39.41 8.588 124.8 443.74 180.4 465.94 93.21 8.673 108.01 62.72 71.24 11.8 0.023 4.62 2.141 3.00 0.812 2.05 16.47 7.217 11.34 3.465 0.071 3.97 0.356 3.86 0.647 0.515 2.65 0.831 2.05 0.33 0.17 0.87 0.10 0.93 0.08  6.60 13.35 4.00 8.26 9.20 22.47 93.16 48.87 440.16 59.97 2.07 5.61 2.82 1.62 1.00  1.233 1.282 1.054 2.522 2.002 3.362 15.92 7.28 44.22 9.898 0.708 1.713 0.365 0.283 0.12  3.00 10.70 15.00 53.50 16.62 143.33 333.33 15.93 264.71 112.50 6.29 36.34 4.45 4.85 0.45  Nb 25.39 23.34 La 34.97 17.99 Nb/Yb 1.81 0.79 La/Yb 2.88 0.33 Zr/Y 3.90 0.79 56.17 24.66 Al3O2/TiO2 TiO2/1000*Nb 1536.53 2267.36 6.68 2.76 TiO2/Zr 27.04 12.75 TiO2/Y 239.14 150.60 TiO2/V Ce/Y 0.82 0.06 1.96 0.22 (La/Yb)N 1.86 0.23 (La/Sm)N 0.88 0.07 (Gd/Yb)N Eu/Eu* 0.56 0.11  10.96 146.62 53.35 143.32  120  121  0.309  0.1866  0.324  0.1958  Sm/Nd 147 Sm/144Nd  Nd/  2.66  4.2  0.50937  0.000007  2.92  0.18  3.2  0.50933  0.000008  2.71  4.0  0.50937  0.000005  0.512789  0.1935  0.320  6.57  2.10  5.57  1.20  -4.7  0.28094  0.000006  0.282877  0.0379  0.266  1.28  441320 7512181 0.34  Normal Basalt  84544 Member basalts  2.69  0.77  4.1  0.50937  0.000006  0.512555  0.1802  0.298  5.30  1.58  2.78  3.06  -1.0  0.28104  0.000010  0.282544  0.0293  0.206  1.16  441033 7504174 0.24  Normal Basalt  202915 Boston Basalt  3.02  3.2  0.50933  0.000006  0.512746  0.1935  0.320  4.75  1.52  2.11  0.59  3.3  0.28116  0.000013  0.282746  0.0309  0.217  1.15  439452 7507669 0.25  Normal Basalt  84545 Clover east basalts  2.25  5.4  0.50944  0.000005  0.512808  0.1906  0.315  4.44  1.40  6.52  2.80  0.6  0.28109  0.000026  0.283154  0.0403  0.284  0.74  438902 7507363 0.21  Normal Basalt  84572 Clover east basalts  2.69  2.19  4.0  0.50936  0.000005  0.511727  0.1336  0.221  13.30  2.94  2.43  2.37  4.4  0.28119  0.000005  0.281860  0.0130  0.092  2.76  438811 7506770 0.25  2.74  2.38  3.3  0.50933  0.000004  0.511289  0.1107  0.183  8.95  1.64  2.53  2.51  3.6  0.28117  0.000005  0.281328  0.0030  0.021  2.10  438196 7506733 0.05  2.73  1.33  3.9  0.50936  0.000006  0.512445  0.1745  0.289  9.70  2.80  1.97  4.14  2.1  0.28113  0.000011  0.282933  0.0352  0.248  1.55  436704 7502763 0.38  Normal Basalt  2.72  1.25  3.9  0.50936  0.000006  0.512464  0.1754  0.290  10.27  2.98  1.98  0.04  4.1  0.28119  0.000014  0.282771  0.0309  0.218  1.75  437337 7505892 0.38  Normal Basalt  2.57  4.4  0.50939  0.000004  0.512774  0.1916  0.317  8.08  2.56  13.93  -11.1  0.28076  0.000006  0.282746  0.0388  0.273  1.51  437045 7505239 0.41  Normal Basalt  7.10  3.87  2.1  0.50927  0.000004  0.512990  0.2103  0.348  7.33  2.55  36.65  -12.8  0.28071  0.000005  0.282742  0.0396  0.279  1.46  436006 7505604 0.41  Normal Basalt  84573 84557 84576 84577 84579 Clover Lake Clover west Clover west Clover west Clover west Suite basalts basalts basalts basalts  LREE Basalt Rhyolite  84574 Clover east basalts  Wasserburg, 1976), 143Nd/144NdDM = 0.5131 and 147Sm/144NdDM = 0.2137(Salters and Stracke 2004).  0.28325 and 176Lu/177HfDM = 0.0384 (Salters and Stracke 2004); and 143Nd/144NdCHUR = 0.512638 and 147Sm/144NdCHUR = 0.1967 (DePaolo &  Epsilon values and model ages calculated using 177Hf/176HfCHUR = 0.282772 and 176Lu/177HfCHUR= 0.0332 (Blichert-Toft & Albarède, 1997) 177Hf/176HfDM =  All Hf isotopic ratios determined by MC-ICP-MS, Nd isotopic ratios determined by TIMS, and concentration data by HR-ICP-MS at the PCIGR, UBC. Initial ratios calculated at 2.68 Ga using Ȝ144Sm = 6.54x10-12 (Lugmair & Marti, 1978) and Ȝ176Lu = 1.865x10-11 y-1 (Scherer et al., 2001).  İNd (i) tCHUR (Ga) tDM (Ga)  Nd/144Nd (i)  143  2ı  0.512626  8.49  6.30  Nd (ppm)  0.512835  2.62  2.04  Nd (m)  2.06  8.84  Sm (ppm)  144  0.65  3.00  143  3.7  0.28118  0.000009  0.282739  0.0305  1.6  0.28112  0.000014  0.283187  0.215  1.90  İHf (i) tCHUR (Ga) tDM (Ga)  Hf/177Hf (i)  176  2ı  Hf/177Hf (m)  176  Lu/  176  0.0404  0.284  Lu/Hf  Hf  1.02  Hf (ppm)  177  442606 7514639 0.29  Northing Easting Lu (ppm)  441884 7514093 0.41  Normal Basalt  Normal Basalt  Rock Type  Suite  84541 Member basalts  84536 Member basalts  Table 3.3: Hf and Nd isotopic compositions of rocks from the Hope Bay Greenstone Belt.  Sample no.1  122  0.298  Lu/Hf  1.68  6.00  0.280  2.08  6.80  0.306  Nd (ppm)  Sm/Nd Sm/144Nd  5.3  1.18  2.47  0.56  2.92  0.50943  0.000006  0.512427  3.2  0.50933  0.000005  0.512595  4.03  3.54  -1.9  0.50906  0.000005  0.512239  0.1796  0.297  34.00  10.10  2.57  2.53  0.9  0.28110  0.000004  0.282360  0.0247  0.174  10.94  445855 7519179 1.90  3.27  2.64  0.2  0.50917  0.000005  0.512036  0.1621  0.268  44.00  11.80  1.80  1.30  10.6  0.28137  0.000004  0.282499  0.0221  0.155  13.90  2.52  2.06  6.0  0.50947  0.000006  0.511640  0.1229  0.203  72.80  14.80  0.42  35.3  0.28206  0.000004  0.282930  0.0169  0.119  10.80  445066 7513292 1.29  Felsic  84589 Flake Lake Suite  2.82  2.36  2.7  0.50930  0.000007  0.511631  0.1319  0.218  82.00  17.90  2.66  2.70  -0.1  0.28107  0.000003  0.282348  0.0250  0.176  10.80  444650 7515305 1.90  Felsic  84591 Flake Lake Suite  2.71  2.23  3.8  0.50936  0.000005  0.511682  0.1315  0.218  42.10  9.16  2.45  2.40  4.4  0.28119  0.000004  0.281737  0.0106  0.075  4.80  Gas Cache Ti Enriched Al Depleted Basalt 436986 7532167 0.36  202910  84516  84538  3.18  2.04  1.7  0.50925  0.000007  0.512368  0.1765  0.292  16.10  4.70  1.78  4.3  0.28119  0.000006  0.282860  0.0325  0.229  3.10  444625 7514723 0.71  Ti Enriched Basalt  2.53  4.6  0.50939  0.000007  0.512760  0.1904  0.315  10.10  3.18  3.19  1.93  -1.6  0.28102  0.000005  0.282885  0.0363  0.255  1.93  443962 7515325 0.49  Ti Enriched Basalt  3.07  3.2  0.50932  0.000007  0.512785  0.1957  0.324  9.30  3.01  6.07  3.36  4.1  0.28119  0.000009  0.283327  0.0418  0.294  1.36  443331 7515307 0.40  Ti Enriched Basalt  2.75  2.37  3.2  0.50933  0.000004  0.511387  0.1166  0.193  14.00  2.70  2.47  2.43  4.6  0.28120  0.000005  0.281537  0.0066  0.046  3.75  434569 7505768 0.17  Dacite  84585 Koignuck Bend Basalt Bend Basalt Bend Basalt Suite  84515  2.81  2.43  2.5  0.50929  0.000008  0.511382  0.1183  0.196  13.90  2.72  2.42  2.37  5.8  0.28123  0.000004  0.281559  0.0064  0.045  4.30  433606 7505416 0.19  Dacite  Koignuck Suite  84586  Wasserburg, 1976), 143Nd/144NdDM = 0.5131 and 147Sm/144NdDM = 0.2137(Salters and Stracke 2004).  = 0.28325 and 176Lu/177HfDM = 0.0384 (Salters and Stracke 2004); and 143Nd/144NdCHUR = 0.512638 and 147Sm/144NdCHUR = 0.1967 (DePaolo &  Epsilon values and model ages calculated using 177Hf/176HfCHUR = 0.282772 and 176Lu/177HfCHUR= 0.0332 (Blichert-Toft & Albarède, 1997) 177Hf/176HfDM  All Hf isotopic ratios determined by MC-ICP-MS, Nd isotopic ratios determined by TIMS, and concentration data by HR-ICP-MS at the PCIGR, UBC. Initial ratios calculated at 2.68 Ga using Ȝ144Sm = 6.54x10-12 (Lugmair & Marti, 1978) and Ȝ176Lu = 1.865x10-11 y-1 (Scherer et al., 2001).  İNd (i) tCHUR (Ga) tDM (Ga)  Nd/144Nd (i)  143  2ı  Nd/144Nd (m)  143  0.1693  2.41  0.73  Sm (ppm)  0.1849  -0.62  2.14  147  1.1  0.28110  0.000009  0.282777  0.0327  -3.4  0.28097  0.000012  0.283144  0.230  0.89  İHf (i) tCHUR (Ga) tDM (Ga)  Hf/177Hf (i)  176  2ı  Hf/177Hf (m)  Lu/177Hf  176  176  0.0423  0.94  Hf (ppm)  435180 7505521 0.21  446046 7518893 2.16  436498 7504990 0.28  Northing Easting Lu (ppm)  Felsic  Felsic  Normal Basalt  Normal Basalt  Rock Type  Suite  84514 Flake Lake Suite  84581 200611 84502 Clover west Clover west Flake Lake Suite basalts basalts  Table 3.3: Hf and Nd isotopic compositions of rocks from the Hope Bay Greenstone Belt.  Sample no.1  123  0.032  Lu/Hf  Nd/  2.73  2.80  2.78  3.6  0.50934  0.000005  0.511653  2.27  3.8  0.50935  0.000007  0.512755  2.42  2.8  0.50930  0.000007  0.1306  0.216  43.50  3.13  2.8  0.50931  0.000005  0.512703  0.1921  0.318  9.00  2.86  1.85  -6.37  4.0  0.28118  0.000008  0.282849  0.0325  0.229  2.01  433968 7551527 0.46  Ti Enriched Basalt  202943 Patch Lake Mafics  2.44  0.85  5.4  0.50943  0.000006  0.512513  0.1741  0.288  6.32  1.82  2.30  1.83  2.7  0.28115  0.000012  0.282609  0.0285  0.201  1.31  433898 7550638 0.26  Normal Basalt  84626 Windy Basalts  2.83  3.7  0.50935  0.000006  0.512775  0.1936  0.320  7.70  2.47  7.51  -10.8  0.28077  0.000008  0.282666  0.0370  0.261  1.46  433092 7551626 0.38  Normal Basalt  202930 Windy Basalts  2.79  2.45  2.6  0.50930  0.000007  0.511233  0.1096  0.181  20.40  3.70  2.56  2.54  2.4  0.28114  0.000006  0.281549  0.0080  0.057  3.59  438992 7514291 0.20  Felsic  84521 Windy Felsics  202931 Windy Felsics  3.08  2.75  -0.6  0.50913  0.000006  0.511316  0.1236  0.205  8.80  1.80  2.42  2.37  6.2  0.28124  0.000004  0.281467  0.0043  0.031  3.07  439610 7511094 0.09  2.83  2.45  2.3  0.50928  0.000007  0.511437  0.1221  0.202  9.90  2.00  2.56  2.55  2.6  0.28114  0.000041  0.281391  0.0048  0.034  3.26  432493 7551376 0.11  Felsic/sedim felsic entry  84551 Windy Felsics  2.25  5.3  0.50943  0.000005  0.512823  0.1917  0.317  4.70  1.49  2.10  3.97  1.7  0.28112  0.000030  0.282914  0.0350  0.247  0.98  434048 7547623 0.24  Normal Basalt  202918 Wolverine Basalts  2.37  16.52  4.7  0.50940  0.000007  0.512922  0.1991  0.329  6.35  2.09  -4.09  0.95  -10.9  0.28076  0.000005  0.282937  0.0424  0.298  1.31  436630 7545657 0.39  Normal Basalt  200649 Wolverine Basalts  Wasserburg, 1976), 143Nd/144NdDM = 0.5131 and 147Sm/144NdDM = 0.2137(Salters and Stracke 2004).  0.28325 and 176Lu/177HfDM = 0.0384 (Salters and Stracke 2004); and 143Nd/144NdCHUR = 0.512638 and 147Sm/144NdCHUR = 0.1967 (DePaolo &  Epsilon values and model ages calculated using 177Hf/176HfCHUR = 0.282772 and 176Lu/177HfCHUR= 0.0332 (Blichert-Toft & Albarède, 1997) 177Hf/176HfDM =  All Hf isotopic ratios determined by MC-ICP-MS, Nd isotopic ratios determined by TIMS, and concentration data by HR-ICP-MS at the PCIGR, UBC. Initial ratios calculated at 2.68 Ga using Ȝ144Sm = 6.54x10-12 (Lugmair & Marti, 1978) and Ȝ176Lu = 1.865x10-11 y-1 (Scherer et al., 2001).  İNd (i) tCHUR (Ga) tDM (Ga)  Nd/144Nd (i)  143  2ı  0.511337  0.1923  0.1151  Nd (m)  0.318  0.190  Sm/Nd 147 Sm/144Nd  144  10.54  12.50  Nd (ppm)  143  3.35  2.38  9.40  2.49  2.04  2.44  Sm (ppm)  3.4  0.28117  0.000005  0.281802  0.0124  2.44  3.5  0.28117  0.000007  0.282785  0.0316  0.087  4.78  202940 Patch Lake Mafics Ti Enriched Al Depleted Basalt 434297 7550413 0.42  2.40  5.6  0.28123  0.000005  0.281463  0.222  2.22  433764 7551849 0.49  Ti Enriched Basalt  202929 Patch Lake Mafics  İHf (i) tCHUR (Ga) tDM (Ga)  Hf/177Hf (i)  176  2ı  Hf/177Hf (m)  176  Lu/  176  0.0046  4.20  Hf (ppm)  Hf  434808 7505652 0.14  Northing Easting Lu (ppm)  177  Dacite  Rock Type  Suite  200632 Koignuck Suite  Table 3.3: Hf and Nd isotopic compositions of rocks from the Hope Bay Greenstone Belt.  Sample no.1  16 14  a  Phonolite Tephriphonolite  12 10 Na2O +K2O 8  Foidite  6 4  PhonoTephrite  Trachyandesite Basaltic Tephrite trachyBasanite Trachy- andesite basalt Basalt  0 35  40  Rhyolite  Dacite  Basaltic Andesite andesite  Picrobasalt  2  Clover 2662Ma Clover Epiclastics Koignuk 2677Ma Windy 2686Ma Square 2690Ma Flake 2700Ma Trachyte LREE-enriched Basalts Ti-Enriched Basalts Normal Basalts Ti-Enriched Al-Depleted Basalt Trachydacite  45  50  55 SiO2  60  65  70  75  80 75 70  b  Rhyolite  Rhyodacite/Dacite  Com./Pan.  65  Trachyte  SiO2 60  Andesite  Trachyandesite Phonolite  55 50  Sub-alk. Basalt  Alkaline basalt Basa./Trach./Neph.  45 40 .001  .01  .1 Zr/TiO2  1  Figure 3.1: a) Alkali vs SiO2 plot of volcanic rocks in this study after Le Bas et al. (1986) b) SiO2 vs Zr/TiO2 plot of volcanic rocks from the Hope Bay Greenstone Belt in this study after Winchester and Floyd (1977)  124  25  a  Clover 2662Ma Clover Epiclastics Koignuk 2677Ma Windy 2686Ma Square 2690Ma Flake 2700Ma LREE Basalts Ti Enriched Basalts Normal Basalts Ti Enriched Al Depleted Basalt  Frequency  20  15  10  5  e M or  76  72  68  64  60  56  52  48  44  40  36  0  SiO2  b 200  70 Y  60 50  Tholeiite  0  500  Zr  Transitional Y  40 30  Calc-Alkaline  20 10 0 0  100  200  300  Zr  Figure 3.2: a) Histogram of SiO2 for samples from mafic and felsic volcanic lithologies of the Hope Bay Greenstone Belt b) Zr vs. Y of samples from mafic and felsic volcanic lithologies of the Hope Bay Greenstone Belt MacLean and Barret (1993)  125  25  LREE-enriched basalt Ti-enriched basalt Normal basalt Ti-enriched, Al-depleted basalt  a 20  15 Al2O3 10  5  0 0.0  0.5  1.0  1.5  2.0  2.5  3.0  3.5  TiO2  b  LREE-enriched basalt Ti-enriched basalt Normal basalt Ti-enriched, Al-depleted basalt  Fetot+Ti  Ti-Enriched  Ti-Enriched Al-Depleted  Fe tholeiite  An de sit e  basaltic komatiite  sa  ite  te  lt  es  leii  Ba  nd  tho  lc  lc A  Mg  Ca  Ca  Al  komatiite LREE / Normal  Mg  Figure 3.3: a) Al3O2 vs TiO2 plot of all basalts in the Hope Bay Greenstone Belt, from this study and Mirimar Dataset b) Modified AFM diagram of least altered rocks from the Hope Bay Greenstone Belt (Jensen; 1976; Grunsky at al. 1992)  126  25  25  Ti-Enriched, Al-Depleted  Ti-Enriched, Al-Depleted 20  20  Ti-Enriched 15  15  Fe2O3  Fe2O3 10  Ti-Enriched 10  LREE / Normal  5  5  LREE / Normal 0 0  5  10  15  20  0  25  0  1  Al2O3 25  2 TiO2  3  4  3  4  30  Ti-Enriched, Al-Depleted  Ti-Enriched, Al-Depleted  20 20 15  LREE / Normal  MgO  MgO  LREE / Normal  10 10 5  Ti-Enriched 0  Ti-Enriched  0 0  5  10  15  20  25  0  Al2O3  Ti-Enriched, Al-Depleted  15 MgO  Figure 3.4: Binary plots of a) Al2O3 vs Fe2O3 b) TiO2 vs Fe2O3 c) Al2O3 vs MgO d) TiO2 vs MgO e) Fe2O3 vs MgO of mafic volcanic rocks from the Hope Bay Greenstone Belt, thin ovals showing groups from Miramar dataset  10  LREE / Normal 5  Ti-Enriched 0 0  5  10  15  2 TiO2  LREE-enriched basalts Ti-enriched basalts Normal basalts Ti-enriched Al-depleted basalt  25  20  1  20  25  Fe2O3  127  Discrimination tool  3  Al  2  O  /T iO  Al2O3/TiO2 Plot  2  ~1  6.  5  Al2O3/TiO2~9  Mafic Volcanics  Al  2  O 3  /T iO 2  Trend 1 Normal  Trend 2 Ti-Enriched  Basalt / Andesite  Fe Basalt  ~4 .3  Trend 3 Ti-Enriched Al-Depleted  1  /Yb (La pe S lo  b) N~ a/Y  Ste ep  e (L  LREE Basalt  p Slo  REE Profile  Fe Basalt  t Fla  )N ~ 4  Modified AFM Jensen, 1976; Grunsky at al.,1992  Normal Basalt  Descriptive Name  LREE-enriched Basalt  Normal Basalt  Fe-, Ti-Enriched Basalt  Fe-, Ti-Enriched, Al-Depleted Basalt  Group Name for this study  LREE- enriched Basalt Group  Normal Basalt Group  Ti-Enriched Basalt Group  Ti-Enriched, Al-Depleted Basalt Group  Normal  Ti-enriched  Short name for figures  LREE  Ti-enriched, Al-depleted  Figure 3.5 Flow diagram describing filtering of geochemical data to determining mafic volcanic groups  128  a 12  Ti-Enriched, Al-Depleted Basalt  300  Ti-Enriched Basalt  10  200  Normal Basalt LREE-enriched Basalt  100  0  6  1 3 5 7 9 11 13 15 17 19 21 23 25 27  Frequency  8  Al2O3/TiO2  4  2  27  More  26  25  24  23  22  21  20  19  18  17  16  15  14  13  12  11  9  10  8  7  6  5  4  3  2  1  0  Al2O3/TiO2  Rock/Chondrites  b 100  Ti-enr ich -enric ed Al-deple h ed ted Normal  LREE  10  Ti-enriched  1 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu  Figure 3.6: a) Histogram of TiO2 concentration of mafic volcanic rocks from the Hope Bay Greenstone Belt b) Chondrite normalized REE diagrams of mafic volcanic rocks from the Hope Bay Greenstone Belt with basalt groups labelled  129  200  600  b)  a)  Ti-enriched 500  Ti-enriched (Doris)  n  Al  -  400  Ti-enriched  50  en Ti-  Nor  -e Ti  d he ric  ed let  ma l/  Zr 100  p De  E  LREE  L RE  150  ric  he  Ti-enriched (Doris)  Normal 0 30  d)  c)  l dA  -D  ep  e let  d V 300  LREE-Enriched Basalts 200 Ti-Enriched Basalts Normal Basalts Ti-Enriched 100 Al-Depleted Basalt 0 50  Ti-enriched (Doris)  40  LREE pl et ed  Ti-enriched 30  rm No  10  al  Ti -e  /L  nr ich  ed  La  RE E  Al  -D e  20  Normal 0 30  0  e)  20  Nb  -e Ti  ic nr  d he  Al  -D  d te le p e  LREE Ti-enriched Normal 0 6000  12000 Ti  18000  6000  12000 Ti  A ed  Y  ted  20  10  18000  0 24000  Figure 3.7: Binary plots of a) TiO2 vs Zr b) TiO2 vs V c) TiO2 vs La d) TiO2 vs Y e) TiO2 vs Nb of mafic volcanic rocks from the Hope Bay Greenstone Belt  10  0  e Ti-  Ti-enriched  ch nri  le ep l-D  24000  130  Lu Er Tm Yb Nd Pm Sm Eu Gd Tb Dy Ho  La Ce 1  10  100  1  10  100  Pr  c) Ti-enriched basalts  Nd Pm Sm Eu Gd Tb Dy Ho  Er Tm Yb  Lu  La Ce  Pr  d) Ti-enriched Al-depleted basalt  b) LREE-enriched basalts a) Normal basalts  Sun+McDon. 1995-REEs Rock/Chondrites  Figure 3.8: Chondrite normalized REE diagrams of a) LREE-enriched basalts b) Ti-enriched basalts c) Normal Basalts d) Ti-enriched Al-depleted basalts-basaltic komatiite from the Hope Bay Greenstone Belt after Sun and McDonough (1995)  131  Ti/100  a)  LREE-enriched basalts Ti-enriched basalts Normal basalts Ti-enriched Al-depleted basalt  Island-arc A B  Ocean-floor B  Calc-alkali B C A  D  Within-plate D  B C  Zr  Y*3  b) MORB+C-A bas+IAT MORB  10000  Ti 5000 Calc-alkali basalt IAT  0 0  100 Zr  200  Figure 3.9: a) Tectonic discrimination diagram after Pearce and Cann (1973) of mafic volcanic rocks from the Hope Bay Greenstone Belt. A B: Island Arc, B: Ocean Floor B C: Calc Alkaline, D: Within Plate b) Tectonic discrimination diagram after Pearce and Cann (1973) of mafic volcanic rocks from the Hope Bay Greenstone Belt. IAT: Island Arc Tholeiite, MORB: Mid Ocean Ridge Basalt, C-a bas: Calc-alkaline Basalt 132  10  LREE-enriched basalts Ti-enriched basalts Normal basalts Ti-enriched Al-depleted basaltbasaltic komatiite  Zr/Y  E - MORB+within plate within plate  E  MORB  Volc arc 1 10  100 Zr  1000  Figure 3.10 Tectonic discrimination diagram after Pearce and Norry (1979) for basalt samples collected during the course of this study. MORB: Mid Ocean Ridge Basalt  133  600  30  Clover 2662Ma Clover Epiclastics Koignuk 2677Ma Windy 2686Ma Square 2690Ma Flake 2700Ma  20  Y  500  400  300  Zr  200  200  10 100  100 0  0.5  1.0  0  0 200  10 40  Nb  100  Nb 20 5  0 0.5 TiO  1.0  0 70  0 18  60 16  50  Al2O3  40  14  La 30 20  12  10 10 0.0  1200  2400  3600  4800  6000 0  Ti  1200  2400  Ti  3600  4800  Figure 3.11: Binary plots of felsic volcanic rocks from the Hope Bay Greenstone Belt, Y vs. TiO2 and Zr vs. TiO2 and Nb vs. TiO2 and V vs. TiO2 and Al3O2 vs. TiO2 and La vs. TiO2  134  0 6000  V  Rock/Chondrites  Sun+McDon. 1995-REEs  b Square Dacite  a Flake Rhyolite 100  10  1  c Windy Lake Dacite  d Koignuk Dacite  e Clover Rhyolite  f Clover Epiclastics  100  10  1  100  10  1  La Ce  Pr  Nd Pm Sm Eu Gd Tb Dy Ho  Er Tm Yb  Lu  La Ce  Pr  Nd Pm Sm Eu Gd Tb Dy Ho  Er Tm Yb  Lu  Figure 3.12 Chondrite normalized REE diagram (Sun and McDunough 1995) for the 6 felsic volcanic suites encountered in the Hope Bay Greenstone Belt  135  0.4  a Source depletion  0.3  Sm/La  Degree of melting 0.2  249878 249879 249880  0.1 0  10  20  30 La/Yb  40  50  60  b  100  Clover 2662Ma Clover Epiclastics Koignuk 2677Ma Windy 2686Ma Square 2690Ma Flake 2700Ma  FI  (La/Yb)N 10  FII FIII 1 0  50  100 YbN  Figure 3.13: a) Sm/La ratio is a measure of source depleting after Plank (2005) and the La/Yb ratio is a measure of the degree of melting of mafic rocks after Cameron et al. (2002) b) La/YbN vs LaN of felsic volcanic rocks from Hope Bay Greenstone Belt with envelopes of FI FII and FIII rock types from Lesher et al. (1985)  136  Flake and CloverTransects Clover Lake Felsic Suite (2662Ma) Clover Sedimentary Suite Clover East Basalts  Calc-alkaline rhyolite  Mix of Normal and LREE Basalts  fault Clover West Basalt Suite  Normal Basalts  Koignuk Felsic Suite (2677Ma)  Calc-alkaline dacite fault  Member Basalt Suite  Normal Basalts  Windy Dacite Unit (2685Ma) Spider Arm Basalt Suite  Mix of Normal and LREE Basalts Windy Lake Felsic Suite (2686Ma)  Calc-alkaline dacite fault  Flake Lake Suite (2716 Ma and 2697Ma)  tholeiitic rhyolite Bend Basalt Suite  Fe-Ti enriched Basalts *outside transect intercalated with Normal Basalts  Figure 3.14: Chemo-stratigraphic reconstruction of the south part of the Hope Bay Greenstone Belt. Width of column does not represent clast or pillow size but instead is 137  138  Dacite interlayer (2691.1±2.0Ma)  enirevloW y ryhprop  stlasaB EERL  Hope Bay Deformation Zone  Wolverine Intrusive Suite (2686Ma)  Volcanic conglomerate (2689 +4.0/-3.6Ma)  Normal Basalts  Wolverine Basalt Suite  Dacite interlayer (2691Ma±2.5Ma )  Fe- Ti Enriched Basalt  Kennet Tarn Basalt Suite  Windy Lake Sedimentary Rocks (2686Ma)  LREE Pillow Basalts  Koig Basalt Suite  Calc-Alkaline Dacite  Koignuk Felsic Suite (2677Ma)  Koignuk River Fault  Wolverine Transect  able  act cont  t tac con  internal contact obscured by cover  trace  e trac  e abl  Figure 3.15: Chemo-stratigraphic reconstruction of the north part of the Hope Bay Greenstone Belt. Width of column does not represent clast or pillow size but instead is used to easily distinguish different packages for rocks.  Doris Basalt Suite  Fe-Ti Fe-Ti  Doris Basalt Suite Mesa Basalt Suite  Normal Basalt Suite  Mesa Basalt Suite  Fe- Ti Enriched Basalt Fe - Ti Enriched, Al Depleted Basalt Ti Enriched, Al Depleted Basaltic Komatiite  Patch Basalt Suite  Windy Basalt Suite Normal Basalis  Calc-Alkaline Dacite  Windy Lake Felsic Suite (2686Ma)  little outcrop relationship unsure  Glen Sedimentary Suite (2678Ma)  Normal Basalt  Discovery Basalt Suite  Koignuk Felsic Suite  Conglomerate Hill Sedimentary Suite (2670.6 ±2.5 )  Doris-Discover Transect  0.5135  DM  0.5130  BSE  0.5125 143  ron  144  c so I a  Nd/ Nd 0.5120  8 2.6  G  LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.5115  0.5110 0.10  0.12  0.14  0.16 0.18 0.20 0.22 Sm/ 144Nd Figure 3.16: 143Nd/144Nd vs 147Sm/144Nd plot with rock groups, with 2.68Ga reference isochron as solid black line. abbreviations: BSE= Bulk Silicate Earth, DM = Depleted Mantle, 147  0.284  DM 0.283  Hf/ 177Hf  BSE  176  a 8G  Is  Hf isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  2.6  0.282  0.281 0.00  ro n oc  0.01  0.02 176  0.03 177  0.04  0.05  Lu/ Hf Figure 3.17: 176Hf/177Hf vs 176Lu/177Hf plot with rock groups, with 2.68Ga reference isochron as solid black line. abbreviations: BSE= Bulk Silicate Earth, DM = Depleted Mantle, 139  Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  (176Hf/177Hf)@2.68Ga  0.2820  0.2810  0.5090  0.5092 0.5094 (143Nd/144Nd)@2.68Ga  (176Hf/177Hf)@2.68Ga  0.28125  0.28100  0.28075  0.28050 0.50925  0.50930  0.50935 143  0.50940  0.50945  0.5095  144  ( Nd/ Nd)@2.68Ga  Figure 3.18: (143Nd/144Nd)@2.68Ga vs (176Hf/177Hf)@2.68Ga plot for all samples from the Hope Bay Greenstone Belt  140  30 LREE-enriched basalt group Normal basalt group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  20  Al2O3/TiO2  10  0 1  2  3  4  5  6  åNd(i) Figure 3.19: åNd(i) vs Al2O3/TiO2 plot with rock groups, relevant samples labelled 30  20  Al2O3/TiO2  10  0 -20  Hf isotopically disturbed group LREE-enriched basalt group Normal basalt group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  -10  0  åHf(i) Figure 3.20: åHf(i)vs Al2O3/TiO2 plot with rock groups, relevant samples labelled 141  10  144  Nd/ Nd  143  0.514 D 0.513 CH eple UR ted 0.512 0.511 slope 147 ~ Sm 144 / Nd 0.510 0.509 Measured 0.508 0.507  143  Ma ntle  144  CHUR  Nd/ Nd  1.0  2.0 143  144  DM  3.0  4.0  Figure 3.21: plot of Sm-Nd model ages. The Nd/ Nd is extrapolated backward (slope depending on Sm/Nd) until it intersects a mantle or chondritic growth curve. In this example, the CHUR model age is 3.05 Ga while the depleted mantle model age is 3.3 Ga.  142  0.5095  0.5093  Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.5092  0.5091  0.5090 0  1  Nd  2  3  4  ôchur  143  144  Nd  Figure 3.22: ( Nd/ Nd)@2.68Ga vs ôCHUR plot of rocks from the Hope Bay Greenstone Belt  U/Pb ages  6 5  Frequency  143  144  ( Nd/ Nd)@2.68Ga  0.5094  4 3 2 1 0  2.1  2.2  2.3  2.4  2.5  2.6  2.7  2.8  2.9  3  3.1  3.2  3.3  3.4  Age (Ga) Nd  Figure 3.23: ôCHUR histogram of rocks from the Hope Bay Greenstone Belt  143  3.5 More  Figure 3.24 0.5095  0.5093 Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.5092  143  0.5091  0.5090 2  3 Nd  4  ô DM  Figure 3.24: (143Nd/144Nd)@2.68Ga vs NdôDM plot of rocks from the Hope Bay Greenstone Belt  12  U/Pb ages  144  ( Nd/ Nd)@2.68Ga  0.5094  Frequency  10 8  Isotopically disturbed group Calc-alkaline felsic group Tholeiitic felsic group All basalt groups  6 4 2 0  2.1 2.2  2.3  2.4  2.5  2.6  2.7  2.8  2.9  3  3.1  3.2  3.3  3.4  Age (Ga) Nd  Figure 3.25: ôDM histogram of rocks from the Hope Bay Greenstone Belt  144  3.5 More  Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.2812  0.2811  0.2810 Hf 176  3  2  1  0 177  4  ôchur  Hf  U/Pb ages  Figure 3.26: ( Hf/ Hf)@2.68Ga vs ôCHUR plot of rocks from the Hope Bay Greenstone Belt  4  Frequency  (176Hf/177Hf)@2.68Ga  0.2813  3  2  1  0  2.1  2.2  2.3  2.4  2.5  2.6  2.7  2.8  2.9  3  3.1  3.2  3.3  3.4  Age (Ga) Hf  Figure 3.27: ôCHUR histogram of rocks from the Hope Bay Greenstone Belt  145  3.5 More  LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.2812  176  177  ( Hf/ Hf)@2.68Ga  0.2813  0.2811  0.2810 2  3  2.5  4  3.5 Hf  ôDM  176  177  Hf  Figure 3.28: ( Hf/ Hf)@2.68Ga vs ôDM plot of rocks from the Hope Bay Greenstone Belt  U/Pb ages  9 8 7  Frequency  6 5 4 3 2 1 0  0  2.1  2.2  2.3  2.4  2.5  2.6  2.7  2.8  2.9  3  3.1  3.2  3.3  3.4  3.5 More  Age (Ga) Hf  Figure 3.29: ôDM histogram plot of rocks from the Hope Bay Greenstone Belt  146  6  DM  4  åNd(i)  Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  2  0  -2 -20  -10  0  10  20  åHf(i)  30  40  Figure 3.30: åNd(i) vs åHf(i) plot of rocks from the Hope Bay Greenstone Belt  6  juv  2  ck data  0  il en  e  le  ro  an  ar  y ra  DM  LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  ole ro hean wh  åNd(i)  early arc  4  o wh  m ck  tle  -2 -2  -1  0  1  2  3  4  åHf(i)  5  6  7  8  9  10  Figure 3.35 åNd(i) vs åHf(i) plot of rocks from the Hope Bay Greenstone Belt with the isotopically disturbed samples removed Juvenile Mantle Array from Vervoorti and Blinchert-Toft (1999), DM value calculated from Salters and Stracke (2004)  147  0.4 Isotopically disturbed group LREE-enriched basalt group Normal basalt group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  Sericite 0.3  K/Al molar ratio 0.2  0.1  Albite 0.0 0.0  0.2  0.4 0.6 Na/Al molar ratio  0.8  1.0  Figure 3.31 K/Al vs Na/Al molar ratio diagram with the least altered area shaded and paths of alteration to sericite and albite indicated with arrows 40 Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  30  20  åHf(i) 10  0  -10  -20 0  2  4  6  8  LOI  Figure 3.32 åHf(i) vs LOI plot of samples from The Hope Bay Greenstone Belt 148  10  30  20  Al2O3/TiO2  10 LREE-enriched basalt group Normal basalt group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0 -2  -1  0  2  1  3  4  åHf(i) Figure 3.34 åHf(i) vs Al2O3/TiO2 plot with basalt sample and isotopically disturbed samples removed, from the Hope Bay Greenstone Belt,  149  5  (176Hf/177Hf)@2.68Ga  0.2820  0.2810  0.5090  0.5092 0.5094 (143Nd/144Nd)@2.68Ga  0.28120  176  177  ( Hf/ Hf)@2.68Ga  0.28130  Isotopically disturbed group LREE-enriched basalt group Normal basalt group Tholeiitic felsic group Calc-alkaline felsic group Ti-Enriched basalt group Ti-Enriched Al-Depleted basalt-basaltic komatiite group  0.28110  0.28100 0.50925  0.50930  0.50935 143  0.50940  0.50945  144  ( Nd/ Nd)@2.68Ga  Figure 3.33 143Nd/144Nd)@2.68Ga vs (176Hf/177Hf)@2.68Ga with basalt sample and isotopically disturbed samples removed, from the Hope Bay Greenstone Belt  150  0.5095  CHAPTER 4 Conclusions and Suggestions for Further Work  151  4.1 Conclusion The creation of a detailed tectonic evolutionary framework for the formation of supracrustal successions has been accomplished by mapping six strategically located transects aided by geochronology, lithogeochemistry, and isotope geochemistry. The Hope Bay Greenstone Belt is characterised by cycles of mafic and felsic volcanism. UPb geochronology from this study supports the previous work that indicated felsic volcanism occurred over 53 m.y. (2716 to 2663 Ma). The stratigraphy of the north part of the belt is relatively continuous, broadly younging to the west. This differs from the south part of the belt where there are a number of stratigraphic packages that are juxtaposed against each other by faults. Despite the shuffling of the stratigraphy in the south part of the belt, the Windy Lake Felsic Suite and Koignuk Felsic Suite can be correlated between the north and south parts of the belt. Chemical compositions of volcanic rocks range from basalt to rhyolite. The felsic suites can be subdivided based on field characteristics, geochronology and geochemical signatures. The Flake Lake Suite is made up of tholeiitic rhyolites whereas the Koignuk, Windy and Square Suites are calc-alkaline dacites. Mafic volcanic rocks are subdivided into four main groups based on chemical composition. The isotopic results show that the Ti-enriched Al-depleted basal and Ti-enriched basalt groups have isotopic compositions that are transitional between the calc-alkaline and the normal basalt group. These Tienriched basalt groups are restricted to discrete stratigraphic suites that commonly vary along strike due to faults or are pinched out stratigraphically. The lower portions of the stratigraphy (older than 2690 Ma) are dominated by mafic volcanic rocks. Basalts with elevated Ti content are almost all found in this lower portion or the Hope Bay Greenstone  152  Belt stratigraphy. Normal basalts are found throughout the stratigraphy with the LREE enriched basalts restricted to the upper part of the stratigraphy (younger than 2690 Ma). The Hope Bay Greenstone Belt has many similarities to other well documented greenstone belts in the Canadian Shield such as the Yellowknife Greenstone Belt and the Abitibi Greenstone Belt. These include age, rock types, stratigraphy and duration of volcanism. This being said, the Hope Bay Greenstone Belt is a unique greenstone belt with respect to the majority of gold (~10 million oz ) deposited in two basalt suites with elevated Ti content. The connection between basalts enriched in Ti and gold, which has been observed previously in the Hope Bay Greenstone Belt, provides the highest exploration potential in the belt for large gold deposits. 4.2 Further work Results from this study have addressed many questions surrounding the evolution of the Hope Bay Greenstone Belt. There are still a number of questions that are unresolved as well as new questions being raised which include: - The Hope Bay Sedimentary Suite is located on an island to the north of the belt. What is its relationship between this suite and the rest of the Hope Bay Greenstone Belt? - Broadly, the north and south parts have similar stratigraphy. The north part of the Hope Bay Greenstone Belt has more voluminous high Ti basalts than the south part of the belt. Does this represent the inhomogeneities of the mantle or different geodynamic settings for the north and south part of the belt? - The Flake Lake Suite is found in the south part of the belt associated with Ti-enriched basalts but basalts enriched in Ti in the north part of the belt have no associated felsic  153  volcanism. Is the Flake Lake Suite rhyolites and Ti-enriched basalts a genetic relationship? (Petrologic modeling could shed light on this) - The sedimentary rocks dated on the east and west limbs of the Boston anticline have significantly different ages. Is there a unconformity and/or faulting in the Boston stratigraphy? Due to lack of outcrop this answer may be difficult to answer, but further dating and examination of outcrops may shed light on the answer to this question. - What is the age of the Clover Sedimentary Suite, surrounding the Clover Lake Felsic Suite? It is inferred to be 2662 Ma from the date on the Clover Lake Felsic Suite but direct dating of the detrital zircons would be useful. - In much of the greenstone belt there is a significant steeply dipping stretching lineation suggesting vertical movement but there are areas that thrusts are inferred. What geodynamic processes were at work on the Hope Bay Greenstone Belt? (horizontal or vertical tectonics) - The majority of the SSP is made up of intrusive rocks with greenstone belts making up ~5% of the rock types. In the Archean earth what made up the other 95% more greenstone belt type rocks, ocean basins or continents? - Detailed petrologic modeling of the Ti enriched Basalt suites was not part of this study. 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Zircons were selected on the basis of grain quality, size, magnetic susceptibility and morphology. All zircon was air abraded prior to dissolution to minimize the effects of post-crystallization Pb-loss, using the technique of Krogh (1982). Single zircon grains were dissolved in sub-boiled 48% HF and 14 M HNO3 (ratio of ~10:1, respectively) in the presence of a mixed 233235  U-205Pb tracer; zircons for 40 hours at 240°C in 300 PL PTFE or PFA microcapsules  contained in high pressure vessels (Parr™ acid digestion vessels with 125 mL PTFE liners). Sample solutions were then dried to salts at ~130°C. Zircon residues were redissolved in ~100 PL of sub-boiled 6.2 M HCl for 12 hours at 210°C in high pressure vessels. These solutions were transferred to 7 mL PFA beakers, dried to a small droplet after addition of 2 PL of 0.5 N H3PO4 . Samples were then loaded on single, degassed zone refined Re filaments in 5 PL of a silicic acid/phosphoric acid emitter (Gerstenberger and Haase, 1997). Isotopic ratios were measured using a modified single collector VG54R thermal ionization mass spectrometer equipped with an analogue Daly photomultiplier. Measurements were done in peak-switching mode on the Daly detector. Analytical blanks during the course of this study were 0.2 pg for U and for Pb in the range of 1-3 pg. U fractionation was determined directly on individual runs using the 233235  U tracer, and Pb isotopic ratios were corrected for fractionation of 0.23%/amu, based  166  on replicate analyses of the NBS-982 Pb standard and the values recommended by Thirlwall (2000). Reported precisions for Pb/U and Pb/Pb dates were determined by numerically propagating all analytical uncertainties through the entire age calculation using the technique of Roddick (1987). Standard concordia diagrams were constructed, and regression intercepts, concordia ages and weighted means calculated with Isoplot 3.00 (Ludwig, 2003). Unless otherwise noted, all errors are quoted at the 2ı level.  A2 Sample descriptions and Results  The descriptions and discussion below accompany the results of the anaylsis (Table 2.3), the U/Pb concordia plots (Figure 2.13) and map of sample locations (Figure 2.14).  a) AJS-01 Flake Lake Suite, quartz rhyolite volcaniclastic This sample is from south of Flake Lake and collected east outside of the Flake transect. The rubble outcrop is several hundred meters in diameter and is composed of banded rhyolite with 10% ~1 mm quartz phenocrysts. Four analysed grains had low U concentrations (28.9-31.4 ppm) and gave concordant and overlapping results, with a concordia intercept of 2697.6±8.9 Ma (with U/Pb decay error and 95% confidence). This sample does not exhibit lead loss, and has large errors on each fraction attributed to both low U contents in the zircons. This age is taken as a good estimate of the crystallization of this rock.  167  b) AJS-05 Windy Lake Felsic Suite, This 15 m wide intermediate to felsic unit lies northeast of Spider Lake, and is bounded by the Member Basalt Suite to the northeast and the Spider Arm Basalt Suite to the southwest. This rock is composed of grey lapilli in a siliceous feldspar rich matrix, with sparse quartz phenocrysts. Five clear and colorless zircon grains weighing between 4 and 7 µg were analyzed. The majority of zircons are low in U and contain between 46.3 to 91.9 ppm. Four of the five anaylses are concordant and nearly overlapping, with the four analyses yielding a concordia intercept of 2685±2.0 Ma. A five point regression through all data give a upper intercept of 2685.8± 2.3 and lower intercept of 1607±200 Ma. Due to the limited dispersion of the data, the concordia intercept at 2685±2.0 Ma is considered the best estimate of the age of this rock.  c) AJS-04 Square Lake Suite, quartz-feldspar dacite tuff This sample was collected from a thin (<3 m) felsic unit found between Wolverine and Patch Lakes, on the Wolverine Transect. This felsic feldspar phyric fragmental unit has lapilli size fragments in a siliceous feldspar rich matrix. In outcrop, it is bounded by mafic volcanic rocks of the Wolverine Basalt Suite, and subsequently folded. Three clear and colorless zircon grains, ranging in weight from 2 to 5 µg, were analysed. One yields a concordant result with a 207Pb/206Pb age of 2690.5±2.3 Ma, whereas the remaining two gave discordant results. A three point linear regression gives an upper intercept of 2691.1±2.0 Ma and a lower intercept of 237 Ma. The upper intercept of 2691.1±2.0 Ma is interpreted as the crystallization age of this tuff.  168  d) AJS-03 Square Lake Suite, quartz-feldspar dacite tuff A thin felsic unit is found as two small outcrops to the south of the Naartok Deposit to the north of the Wolverine transect. This unit is bounded on both sides by pillow basalts of the Wolverine Basalt Suite. This feldspar phyric volcaniclastic rock has many angular feldspar grains with some quartz eyes. The zircons selected for anaylsis were clear and colorless, with four fractions ranging in mass from 2-7 µg. Variably discordant results (5.3-1.0%) are attributed to minor Pb loss. A linear regression gives an upper intercept of 2691.7 ±2.5 Ma and a lower intercept of 250±180 Ma. The former is interpreted as the crystallization age of this tuff.  e) AJS-06 Boston Sedimentary Suite This sample from the shore of Spider Lake and is part of the west limb of the Boston Anticline. The quartz wacke is surrounded by wacke beds and thin argillite beds, all of which have been folded on an outcrop scale. Five clear and colorless zircon grains selected for anaylsis range in weight from 2 to 8 µg. One analysis is concordant with a 207  Pb/206Pb date of 2690 Ma, while the remaining vary from 1.9 to 7.6% discordant, with  207  Pb/206Pb ages of 2685.2 ± 4.0 Ma, 2675.8 ± 2.5 Ma, 2695.3 ± 3.6 Ma, and 2687.5 ± 6.0  Ma. The youngest 207Pb/206Pb date of 2675.8 ± 2.5 Ma provides a maximum estimate for deposition.  169  f) LMB-55 Glen Lake Sedimentary Unit This siltstone sample was taken from an outcrop to the south of Discovery Bay. This sedimentary unit is located between the Discovery Basalt Suite to the west and the Windy Lake Felsic Suite to the east. Five clear and colorless zircon grains selected for anaylsis range in weight from 3 to 8 µg. Three of the grains were low in U, ranging from 53.6 to 83.9, with the remaining samples containing 113.9 and 110.5. The four low U analyses were found to be concordant to slightly reversely discordant, with 207Pb/206Pb dates of 2683.7 ±1.9 Ma, 2679.4 ±1.7 Ma, 2682.1 ±1.9 Ma and 2683.3 ±1.7Ma. One sample was found to be 16.6% discordant with 207Pb/206Pb age of 2678.4±2.8 Ma. The youngest 207  Pb/206Pb date of 2678.4±2.8 Ma provides a maximum estimate of deposition.  g) LMB-56 Conglomerate Hill Sedimentary Suite This sample taken on the east shore of Hope Bay from a sandstone interbedded with a pebbly conglomerate. The sample is mostly made up of white to cream feldspar grains and few clear quartz grains. Five clear and colorless zircon grains selected for anaylsis range in weight from 3 to 13 µg. All of the grains are low in U, ranging from 27.3 to 107.1 ppm . These samples were found to be concordant to slightly reversely discordant, with207Pb/206Pb dates of 2684.4 ±1.8 Ma, 2675.8 +2.1/-2.2 Ma, 2677.9 ±1.7 Ma, 2670.6 ±2.5 Ma and 2682.1 ±2.5 Ma. The youngest 207Pb/206Pb date of 2670.6 ±2.5 Ma provides a maximum estimate for deposition.  170  APPENDIX B: Procedures of Geochemical-Isotopic Analysis PCIGR  171  Quality Assurance and Dissolution Procedures Samples with large grain sizes will not homogenize during dissolution so original sample powders, which were ground by ALS Chemex, were inspected under microscope to confirm that particle sizes were less than 60um in diameter. Procedural duplicates (84577, 84514) were included to monitor data reproducibility. The USGS reference material G-2 granite was analyzed to monitor the accuracy of the concentration results. Both trace element and isotopic compositions for each sample were determined from a single digestion procedure.  Digestion The samples were split into two groups, 1) those that do contain refractory minerals (zircon bearing) and 2) those that do not contain refractory minerals. Samples identified as containing refractory minerals underwent high temperature dissolution. This involved sample powder (100 to 150 mg) being mixed with 5.0 mL of 48% HF and 1.0 mL of 14 N HNO3 and placed in steel-jacketed acid-washed high-pressure PTFE bombs and placed in an oven at 190oC for 5 days. Digested samples were dried on a hotplate overnight at 130OC, reconstituted in 6.0 mL of 6 N HCl and re-bombed for 24 hours at 190OC. Samples that lacked refractory minerals underwent standard hotplate dissolution. This procedure involved rock powders (100 to 250 mg) being placed in 15 mL screw-top Savillex® PFA beakers with 10.0 mL of 48% HF and 1.0 mL of 14 N HNO3. The beakers were then placed on a hotplate for 48 hours at 130OC and were occasionally placed in an ultrasonic bath to aid in complete digestion. After digestion, samples were dried down overnight on a hotplate at 130oC, reconstituted in 6.0 mL of 6 N sub-boiled  172  HCl and re-dissolved for 24 hours at 130oC. Dissolved samples in of both groups were transferred to Savillex® and dried on a hotplate. Each sample was then re-dissolved in HCl (4 g) on a hotplate and an aliquot for trace element analysis was removed and placed in a separate Savillex® beaker. The remaining sample solution was kept for isotope ratio determination (see column chemistry procedures below).  Trace Element Anaylsis Procedure Detailed procedures and instrument analytical operating parameters can be found in Petorius et al. (2005). The trace element aliquot was diluted by 800 to 2000 times in 1% HNO3 with 1 ppb In as in internal standards. Trace element concentrations were analyzed on a Thermo Finnigan Element2 high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). Trace element concentrations from PCIGR are shown in Table 3.4. Two to three procedural blanks included in each batch of ten samples analyzed and were within acceptable values. Results for USGS reference material (G-2) are within error (2ı) of the range of previously published values (Robinson et al., 1986; Totland et al., 1992; Govindaraju, 1994; Liang et al., 2000; Raczek et al., 2000; Meisel et al., 2001; Pretorius et al., 2006). A comparison and brief discussion of trace element results from PCIGR and ALS Chemex can be found in Appendix E.  Sm-Nd and Lu-Hf Column Chemistry Procedure The following Hf separation procedures are modified from Patchett and Tatsumoto (1980) and Blichert-Toft et al. (1997). The REE (including Nd) were separated from Hf using a Teflon® column with Biorad AG 50W-X8 100-200 mesh resin and a  173  progressively increasing concentration of HCl from 1.5 N to 4.0 N. The Hf separate was then passed through a polypropylene column and a Savillex™ column, using a 0.1 N HF / 0.5 N HCl solution and Biorad AG 1-X8 100-200 mesh resin, and a 0.3 N HF / 2.5 N HCl solution and Biorad AG 50W-X8 200-400 mesh resin, respectively. Nd was separated from the REE in a separate quartz column using 0.16 N HCl and HDEDEcoated Teflon® beads.  Instrumentation and Analysis The Nd isotopic measurements were made on a Thermo Finnigan Triton-TI thermal ionization mass spectrometer (TIMS) in static mode with relay matrix rotation on double Be-Ta filaments. The results are shown in Table 2.5. The measured compositions of each sample are the mean of 135 analyses (as blocks of 15 cycles). Samples were measured in 3 batches over four days. During the analysis of each batch the La Jolla Nd standard was measured six times giving a mean value of 143Nd/144Nd = 0.511855 ± 0.000006 (2ı), 0.511863 ± 0.000009 (2ı) and 0.511829 ± 0.000009 (2ı) for the three batches, respectively. Two procedural duplicates are within analytical error (2ı). All measurements were corrected for internal mass fractionation using 146Nd/144Nd = 0.7219. The Nd isotopic compositions of the USGS G-2 reference material are within analytical error (2ı) of previously reported results (Weis et al., 2006). The Hf isotopic compositions were analyzed in static mode on the PCIGR Nu Plasma multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) in the “dry” plasma mode using a desolvating nebulizer (DSN). Measured ratios and agecorrected values are shown in Table 2.5. The measured compositions of each sample are  174  the mean of 60 analyses (3 blocks of 20 cycles). The measured Hf isotopic ratios were corrected for interferences by monitoring Lu and Yb beams throughout each analysis. Samples were measured in 3 separate batches over three days. Standard sample bracketing of the Hf JMC 475 in-house standard gave a mean value of 176Hf/177Hf = 0.282163 ± 0.000012 (2ı; n=12), 0.282174 ± 0.000009 (2ı; n=12) and 0.282172 ± 0.000004 (2ı n=13) for both the three batches respectively; these values are within the range of previously published values (Blichert-Toft et al., 1997; Chauvel & Blichert-Toft, 2001; Goolaerts et al., 2004). The three procedural duplicates are within analytical error (2ı). All reported values were normalized to 176Hf/177Hf = 0.282160 as suggested by Vervoort & Blichert-Toft (1999). The Hf isotopic compositions of the USGS G-2 reference material are within analytical error (2ı) of previously reported results (Weis et al., 2006).  175  References: Patchett P. J. and Tatsumoto M. (1980), A routine high-precision method for Lu-Hf isotope geochemistry and chronology. Contr. Mineral. Petrol., 75, 263-267. Blichert-Toft J., Chauvel C., and Albarède F. (1997), Separation of Hf and Lu for highprecision isotope analysis of rock samples by magnetic sector-multiple collector ICP-MS. Contrib. Mineral. Petrol., 127, 248-260. Vervoort J. D. and Blichert-Toft J. (1999), Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time. Geochim. Cosmochim. Acta 63, 533556. Weis D., Kieffer B., Maerschalk C., Barling J., de Jong J., Williams G., Hanano D., Pretorius W., Mattielli N., Scoates J.S., Goolaerts A., Friedman R. and Mahoney J.B. (2006), High-precision isotopic characterization of reference materials by TIMS and MC-ICP-MS. Geochem. Geophys. Geosyst., 7,  176  APPENDIX C: Major and Trace Element Abundances of Samples from the Hope Bay Greenstone Belt, (ALS CHEMEX)  177  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample Rock Type UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  84585 CalcAlkaline Dacite 434569 7505760 Koignuck Felsic Suite 62.29 0.49 14.30 9.76 0.10 2.47 1.59 1.31 2.88 0.11 0.01 <0.01 0.02 4.53 99.85  84586 CalcAlkaline Dacite 433606 7505408 Koignuck Felsic Suite 64.46 0.56 14.39 4.93 0.07 1.93 3.41 4.10 1.42 0.12 0.01 0.01 0.02 3.85 99.27  200630 CalcAlkaline Dacite 434584 7505520 Koignuck Felsic Suite 65.59 0.52 16.50 3.39 0.07 1.20 2.07 4.51 1.94 0.16 0.01 0.02 0.04 3.95 99.98  200632 CalcAlkaline Dacite 434808 7505648 Koignuck Felsic Suite 62.42 0.55 16.75 5.14 0.05 2.81 3.08 4.10 1.20 0.11 0.01 0.03 0.02 3.81 100.10  202914 CalcAlkaline Dacite 433145 7505904 Koignuck Felsic Suite 64.03 0.50 15.74 5.23 0.04 3.37 3.33 3.75 1.20 0.14 0.02 0.02 0.02 2.34 99.74  202926 CalcAlkaline Dacite 434967 7506416 Koignuck Felsic Suite 64.80 0.61 15.81 5.41 0.05 2.45 5.55 2.58 1.17 0.20 0.02 0.03 0.03 1.22 99.93  202927 CalcAlkaline Dacite 434965 7506416 Koignuck Felsic Suite 66.99 0.43 14.83 4.52 0.04 1.54 5.07 4.14 0.21 0.09 0.02 0.03 0.01 1.87 99.79  202932 CalcAlkaline Dacite 434944 7506352 Koignuck Felsic Suite 67.21 0.48 14.83 4.32 0.06 1.52 3.31 3.32 1.08 0.11 0.01 0.03 0.02 3.15 99.44  84520 CalcAlkaline Dacite 441602 7510752 Koignuck Felsic Suite 63.03 0.53 16.10 4.78 0.07 2.13 3.30 4.35 1.68 0.20 <0.01 0.03 0.04 3.41 99.66  66 80 19.8 42 27 75 0.8 26.4 27.7 144.0 5.0 136.5 4 10.4 16.1 31.9 3.6 13.6 2.8 0.7 2.5 0.3 1.9 0.3 1.1 0.1 1.0 0.1 <5 2.0 0.6 17 1 0.5 1  68 90 12.3 22 24 71 0.5 30.5 141.5 190.0 6.0 147.5 4 12.6 16.4 33.8 3.9 14.8 3.0 0.8 2.8 0.4 2.3 0.4 1.3 0.1 1.2 0.1 13 2.0 0.6 17 1 0.5 <1  61 90 7.3 25 7 53 1.4 30.9 124.5 311.0 5.0 147 4 7.7 14.9 29.6 3.4 12.2 2.4 0.7 2.0 0.3 1.4 0.3 0.7 0.1 0.6 0.1 <5 2.0 <0.5 19 1 0.5 <1  79 110 15.3 41 34 86 0.9 27.3 231.0 265.0 5.0 152.5 4 10.0 17.8 32.9 3.7 13.1 2.5 0.8 2.4 0.4 1.9 0.4 1.1 0.1 0.9 0.1 5 3.0 0.7 20 2 0.5 1  72 190 15.4 51 72 62 0.3 19.6 192.0 272.0 7.0 150.5 4 13.5 16.8 34.3 3.9 14.6 2.9 0.9 2.9 0.4 2.4 0.5 1.3 0.2 1.2 0.2 9 2.0 0.5 19 <1 0.6 1  69 180 13.8 21 22 48 1.4 24.9 235.0 185.5 8.0 164 4 17.0 18.4 38.5 4.5 17.7 3.6 1.0 3.5 0.5 2.8 0.6 1.6 0.3 1.5 0.3 <5 2.0 0.6 19 <1 0.6 1  64 140 9.7 28 5 36 0.2 2.7 247.0 71.3 5.0 124 4 10.3 17.8 33.3 3.6 13.0 2.4 0.7 2.3 0.3 1.7 0.3 1.0 0.2 1.0 0.1 <5 3.0 0.6 18 <1 0.5 1  70 120 8.5 20 23 60 1.1 23.7 230.0 185.0 5.0 126.5 4 10.6 17.0 31.3 3.4 11.8 2.2 0.8 2.3 0.3 1.7 0.4 1.0 0.2 0.9 0.1 <5 3.0 0.6 18 <1 0.5 <1  78 80 13.1 24 24 54 1.4 43.6 244.0 336.0 7.0 123.5 3 9.6 21.2 44.4 5.1 18.0 3.1 0.9 2.8 0.4 1.8 0.3 1.0 0.1 0.9 0.1 <5 3.0 0.8 17 1 0.5 1  178  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample Rock Type UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  84546 CalcAlkaline Dacite 441040 7512112 Koignuck Felsic Suite 56.23 0.75 17.41 7.69 0.09 3.44 6.24 2.80 1.71 0.25 0.01 0.03 0.04 3.34 100.05  202923 CalcAlkaline Dacite 431433 7548960 Koignuck Felsic Suite 55.00 0.69 15.24 8.30 0.10 5.21 4.92 3.92 0.18 0.14 0.02 0.02 0.02 6.22 99.97  1001 CalcAlkaline Dacite 433414 7549968  1002 CalcAlkaline Dacite 434907 7546448  202931 CalcAlkaline Dacite 432493 7551376 Windy Square Lake Square Lake Felsics 64.95 68.09 66.44 0.40 0.25 0.42 15.05 15.92 14.49 3.33 2.41 2.82 0.05 0.02 0.06 1.18 1.01 2.27 3.40 1.37 2.54 4.66 6.00 4.64 1.66 1.50 2.11 0.06 0.07 0.07 0.00 0.00 0.03 0.01 0.01 0.01 0.05 0.03 0.03 4.02 2.58 3.60 98.82 99.26 99.54  249878 CalcAlkaline Dacite 431446 7560720 Windy Felsics 60.21 0.50 15.03 5.17 0.06 2.87 4.14 4.40 1.61 0.24 0.01 0.05 0.03 5.23 99.55  249879 CalcAlkaline Dacite 430929 7561216 Windy Felsics 62.22 0.49 16.87 5.19 0.07 2.22 3.34 4.38 2.09 0.18 <0.01 0.07 0.05 2.31 99.49  249880 CalcAlkaline Dacite 430653 7557888 Windy Felsics 67.79 0.39 15.14 3.27 0.03 0.89 1.87 6.57 0.65 0.11 <0.01 0.05 0.04 2.59 99.39  84550 CalcAlkaline Dacite 440476 7512448 Windy Felsics 68.41 0.48 13.84 3.04 0.06 1.09 2.56 2.62 2.88 0.06 0.01 0.02 0.06 4.84 99.98  114 130 21.2 46 48 83 1.1 47.3 264.0 428.0 12.0 197 5 18.2 26.8 54.1 6.2 23.1 4.3 1.4 4.3 0.6 3.3 0.6 1.9 0.3 1.7 0.3 6 4.0 0.8 22 2 0.7 2  154 180 30.3 116 27 82 0.4 3.8 130.0 86.1 5.0 107.5 3 16.4 11.2 24.6 3.0 12.3 2.6 0.8 2.9 0.5 2.8 0.6 1.8 0.3 1.6 0.3 <5 1.0 <0.5 17 <1 <0.5 1  63 60 10.6 31 21 77 3.9 53.3 86.0 451.0 2.0 94.5 3 6.9 7.3 14.8 1.8 7.9 1.7 0.7 1.7 0.2 1.2 0.2 0.6 0.1 0.5 0.1 9 2.0 0.5 21 1 0 3  33 20 6.3 57 12 54 0.8 38.6 121.0 249.0 2.0 110 3 6.2 6.2 13.1 1.6 7.1 1.5 0.5 1.5 0.2 1.0 0.2 0.6 0.1 0.6 0.1 <5 1.0 0.5 22 1 0 2  105 80 17.4 45 21 56 1.1 38.4 408.0 311.0 5.0 136 3.7 10.0 38.5 83.7 10.0 38.1 5.9 1.4 4.4 0.5 2.1 0.4 1.1 0.1 1.0 0.1 <5 5.0 0.97 17.5 1 0.4 1  82 40 13.4 32 10 58 1.2 46.7 629.0 367.0 3.9 126 3.4 8.0 26.9 58.7 6.9 26.9 4.0 1.2 3.4 0.4 1.7 0.3 0.9 0.1 0.7 0.1 5 3.5 0.79 20.1 1 0.4 1  45 30 8.4 14 <5 41 0.6 13.9 325.0 199.5 3.3 119 3.4 5.2 15.9 32.2 3.7 13.7 2.2 0.7 1.9 0.2 1.2 0.2 0.6 0.1 0.5 0.1 <5 2.6 0.61 16.3 1 0.4 3  25 90 5.2 10 12 55 1.9 52.8 141.5 463.0 9.0 198.5 5 16.3 29.2 60.6 7.1 26.4 4.7 1.1 4.4 0.6 2.9 0.6 1.7 0.2 1.6 0.3 5 4.0 0.9 16 1 0.6 2  72 110 6.7 24 33 32 0.9 34.6 86.9 335.0 3.0 104.5 3 7.5 11.8 22.0 2.5 9.7 1.9 0.6 1.9 0.3 1.3 0.3 0.7 0.1 0.6 0.1 <5 2.0 0.5 18 <1 <0.5 1  179  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample Rock Type UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  84551 CalcAlkaline Dacite 439610 7511088 Windy Felsics 67.69 0.30 13.68 3.08 0.04 0.99 3.76 4.33 1.32 0.07 0.01 0.04 0.03 4.79 100.15  249517 CalcAlkaline Dacite 440384 7512368 Windy Felsics 69.17 0.42 14.18 3.32 0.06 0.67 2.57 4.23 1.69 0.09 <0.01 0.02 0.05 3.05 99.53  249521 CalcAlkaline Dacite 439611 7512016 Windy Felsics 66.60 0.34 14.78 2.86 0.05 1.59 2.63 3.76 2.21 0.09 <0.01 0.02 0.02 5.10 100.05  249522 CalcAlkaline Dacite 439587 7511424 Windy Felsics 64.12 0.56 15.62 5.21 0.09 0.93 3.52 3.64 2.02 0.19 <0.01 0.04 0.04 3.61 99.59  84573 CalcAlkaline Rhyolite 438196 7506720 Clover Lake felsics 75.08 0.09 12.90 0.79 0.02 0.42 0.61 3.11 4.15 0.04 0.01 <0.01 0.08 1.50 98.81  40 80 6.8 12 7 47 0.6 31.6 284.0 296.0 4.0 94.1 3 6.6 14.4 26.9 3.0 11.2 2.1 0.6 1.9 0.3 1.2 0.2 0.7 0.1 0.7 0.1 <5 3.0 0.5 17 1 <0.5 2  25 30 5.2 6 <5 72 1.2 48.7 195.0 361.0 12.0 263 6.8 22.6 38.4 82.4 9.8 37.5 6.5 1.4 5.8 0.8 4.4 0.8 2.4 0.3 2.2 0.3 6 5.8 1.3 18.8 2 0.8 7  44 20 7.8 12 <5 35 1.4 49.2 195.5 294.0 4.0 122 3.5 10.0 15.2 29.0 3.2 12.7 2.5 0.6 2.2 0.3 1.8 0.3 0.9 0.1 0.9 0.1 <5 3.0 0.62 21.3 1 0.4 2  27 10 8.9 8 6 87 1.6 48.9 307.0 380.0 6.8 156.5 4.5 18.9 21.9 45.5 5.3 20.5 4.0 1.2 3.9 0.6 3.5 0.7 2.0 0.3 1.9 0.3 11 3.7 0.95 22.3 2 0.6 5  8 140 1.4 5 <5 31 1.8 85.2 39.0 670.0 3.0 56.5 2 3.4 10.7 21.4 2.3 7.9 1.5 0.2 1.2 0.1 0.7 0.1 0.3 <0.1 0.2 <0.1 <5 3.0 1.1 18 1 <0.5 2  180  1004  249533  249534  249535  Epiclastic Andesites  Epiclastic Andesites  Epiclastic Andesites  Epiclastic Andesites  437602 7503312 Clover Sediments 58.11 0.62 15.87 7.61 0.09 4.41 5.75 3.50 0.31 0.08 0.00 0.03 0.02 2.48 98.90  437714 7504816 Clover Sediments 58.11 0.97 17.37 6.69 0.05 4.11 1.99 5.12 0.37 0.19 <0.01 0.03 0.01 4.24 99.24  437627 7504080 Clover Sediments 55.53 0.70 15.48 8.10 0.06 3.94 3.21 3.85 0.60 0.15 <0.01 0.02 0.02 6.99 98.65  437691 7503024 Clover Sediments 58.03 0.59 14.31 6.79 0.32 5.42 2.12 4.62 0.14 0.15 0.03 0.02 0.02 5.77 98.32  136 180 28.4 90 62 85 0.6 9.3 279.0 109.5 5.0 125.5 4 15.7 12.8 24.6 2.8 12.0 2.5 1.0 2.7 0.4 2.6 0.5 1.6 0.2 1.5 0.2 5 2.0 0.6 18 1 0 1  148 10 27.0 20 46 102 0.4 7.3 214.0 132.5 8.0 166 4.5 21.4 14.5 37.6 3.9 16.9 3.6 1.2 4.2 0.7 4.0 0.9 2.4 0.3 2.3 0.3 <5 2.6 0.6 21.2 1 0.6 1  104 50 20.5 45 76 437 0.8 13.9 145.5 157.0 6.6 150 4 16.8 11.8 30.8 3.3 13.6 2.9 1.0 3.4 0.5 3.2 0.6 1.9 0.3 1.8 0.3 <5 2.2 0.46 17.7 1 0.5 2  96 240 24.3 134 32 164 0.3 2.4 120.0 187.5 6.8 144 3.7 11.9 14.3 37.1 3.7 15.0 2.9 0.9 3.1 0.4 2.3 0.5 1.3 0.2 1.2 0.2 48 2.5 0.5 16 1 0.4 3  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  84547  84548  84549  84574  249536  202922  249537  249539  249540  Rock Type  LREE basalt  LREE basalt  LREE basalt  LREE basalt  LREE basalt  LREE basalt  normal basalt  normal basalt  normal basalt  440554 7511728 LREE Basalts 43.70 1.09 18.04 14.07 0.28 4.88 11.33 1.27 0.08 0.24 0.05 0.06 <0.01 5.23 100.30  440432 7512352 LREE Basalts 50.01 1.06 14.98 12.22 0.18 5.78 8.71 3.12 0.09 0.29 0.01 0.04 0.01 3.01 99.49  441038 7512032 LREE Basalts 49.46 0.92 15.37 10.07 0.18 4.49 10.42 2.42 0.06 0.12 0.05 0.03 0.01 5.55 99.15  438811 7506768 Clover East Basalts 52.38 0.79 19.01 8.26 0.12 5.67 5.53 4.32 0.38 0.16 0.01 0.04 0.02 3.37 100.05  437719 7502992 Clover East Basalts 51.30 0.94 18.67 8.28 0.13 4.99 5.02 5.20 0.05 0.09 0.01 0.03 0.01 3.75 98.47  431509 7549024  441162 7504896 Boston Koig Basalts Basalt 43.41 23.98 0.93 0.39 16.54 7.47 11.88 12.34 0.12 0.16 9.36 20.97 4.17 3.02 2.90 0.49 0.23 0.16 0.16 0.03 0.02 0.38 0.01 0.01 0.01 <0.01 10.20 28.80 99.95 98.20  441436 7503088 Boston Basalt 46.79 0.80 16.00 11.65 0.19 6.66 12.25 1.26 0.03 0.06 0.05 0.02 <0.01 3.84 99.61  442186 7502096 Boston Basalt 50.64 0.75 13.19 9.03 0.26 5.01 10.69 2.06 0.11 0.05 0.15 0.02 0.01 7.08 99.05  292 250 65.9 141 98 106 0.1 0.9 524.0 15.0 7.0 98.4 3 27.8 18.5 44.5 5.9 24.8 5.3 1.8 5.5 0.8 4.9 1.0 3.1 0.4 2.9 0.4 <5 1.0 <0.5 21 1 <0.5 2  252 100 43.7 42 56 91 0.3 1.3 321.0 51.2 7.0 114 3 24.5 18.8 45.8 6.1 25.7 5.5 1.6 5.3 0.8 4.5 0.9 2.7 0.4 2.5 0.4 <5 1.0 <0.5 18 1 <0.5 2  245 350 59.0 239 77 83 0.1 0.7 237.0 21.4 4.0 53.9 2 21.8 8.7 21.7 2.9 12.0 2.9 1.0 3.3 0.6 3.7 0.8 2.5 0.4 2.4 0.4 <5 1.0 <0.5 18 1 <0.5 1  189 110 33.1 92 70 94 0.8 12.7 370.0 214.0 6.0 119 3 16.5 10.4 23.8 3.1 13.2 3.0 0.9 3.0 0.5 3.0 0.6 1.8 0.2 1.7 0.2 17 1.0 <0.5 19 1 <0.5 1  242 140 35.6 81 10 84 0.2 0.4 270.0 62.1 4.7 121 3.1 18.1 9.9 24.0 2.5 10.8 2.4 1.0 3.1 0.5 3.2 0.7 2.1 0.3 2.1 0.3 <5 1.7 0.34 19.4 1 0.4 15  176 220 44.8 172 51 119 0.3 5.7 73.1 137.0 6.0 138 4 20.8 12.8 28.7 3.7 14.8 3.4 1.0 3.6 0.6 3.5 0.8 2.3 0.3 2.1 0.4 <5 1.0 <0.5 14 <1 0.5 1  263 340 50.2 171 112 95 0.1 0.4 224.0 10.2 1.8 43 1.3 16.8 2.1 7.0 0.9 4.8 1.6 0.7 2.3 0.4 3.0 0.7 2.0 0.3 2.0 0.3 <5 0.2 <0.05 16.3 <1 0.1 10  241 1080 63.6 244 110 81 0.1 2.5 160.5 52.5 2.0 51 1.4 18.3 3.5 9.4 1.1 6.0 1.8 0.8 2.6 0.5 3.2 0.7 2.1 0.3 1.9 0.3 <5 0.3 <0.05 14.3 1 0.1 12  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  181  142 2860 105.0 917 8 253 0.4 7.4 75.4 26.0 1.3 36 1 8.8 1.9 5.9 0.7 3.5 0.9 0.4 1.3 0.2 1.6 0.4 1.0 0.2 0.9 0.2 8 0.3 <0.05 9 <1 0.1 28  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  249541  84545  84572  84580  84575  84576  84577  84578  84579  Rock Type  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  441048 7502736 Boston Basalt 47.69 0.98 15.20 12.46 0.20 7.22 9.27 0.16 0.02 0.06 0.04 0.02 <0.01 4.90 98.22  439452 7507664 clover east basalts 48.65 0.76 14.66 9.25 0.20 3.25 9.70 3.22 0.37 0.06 0.03 0.01 0.01 9.54 99.70  438902 7507360 clover east basalts 44.84 0.60 11.09 12.27 0.24 10.47 13.66 0.79 0.08 0.04 0.13 0.01 <0.01 5.85 100.05  437808 7503584 clover east basalts 47.44 0.91 15.10 11.65 0.25 4.85 11.65 2.06 0.23 0.07 0.04 0.02 0.01 4.94 99.21  437265 7506128 clover west basalts 45.85 0.95 14.96 13.66 0.22 6.23 12.37 1.22 0.08 0.08 0.01 <0.01 <0.01 3.56 99.20  437337 7505888 clover west basalts 49.20 1.12 14.08 13.61 0.20 6.31 10.25 2.11 0.23 0.10 0.01 0.02 0.01 2.99 100.25  437045 7505232 clover west basalts 47.34 0.87 14.30 12.99 0.21 7.64 10.78 1.39 0.30 0.08 0.04 0.01 0.01 3.23 99.19  436744 7506272 clover west basalts 47.13 0.84 14.19 13.43 0.22 7.04 11.76 1.59 0.12 0.06 0.04 0.01 <0.01 2.96 99.39  436006 7505600 clover west basalts 40.32 0.87 11.58 17.70 0.31 12.50 10.41 0.14 0.06 0.06 0.06 0.01 <0.01 6.06 100.10  290 330 49.1 120 112 105 0.0 0.2 119.5 4.8 2.1 53 1.6 18.6 2.2 7.3 0.9 5.4 1.7 0.7 2.6 0.5 3.4 0.7 2.2 0.3 2.3 0.3 <5 0.3 <0.05 15.1 <1 0.1 10  260 280 46.9 113 114 69 0.6 9.3 79.4 88.3 2.0 38.8 1 14.4 2.5 6.3 1.0 4.9 1.6 0.6 2.0 0.4 2.6 0.5 1.7 0.2 1.6 0.2 <5 <1 <0.5 14 1 <0.5 2  202 1040 59.2 294 81 75 0.1 0.6 92.3 11.2 2.0 115.5 3 14.8 2.1 5.9 0.9 4.8 1.6 0.6 2.0 0.4 2.5 0.5 1.7 0.2 1.6 0.3 <5 <1 <0.5 13 1 <0.5 1  302 310 50.9 132 130 76 <0.1 2.6 157.0 28.8 2.0 53.2 2 19.8 3.2 8.1 1.2 6.3 2.1 0.8 2.7 0.5 3.2 0.7 2.2 0.3 2.1 0.3 <5 <1 <0.5 16 1 <0.5 <1  325 190 50.7 75 114 97 0.1 0.9 50.7 10.2 3.0 62.6 2 22.9 4.3 11.0 1.7 8.2 2.6 0.9 3.1 0.5 3.9 0.8 2.6 0.3 2.4 0.4 7 <1 <0.5 18 1 <0.5 1  327 100 51.9 67 138 102 0.2 3.9 208.0 37.6 5.0 81.3 2 26.8 5.9 14.5 2.1 10.6 3.2 1.0 3.8 0.7 4.6 0.9 2.9 0.4 2.7 0.4 <5 <1 <0.5 17 1 <0.5 3  302 300 52.1 114 124 85 0.1 4.2 90.5 31.2 2.0 55.3 2 20.0 3.3 8.3 1.3 6.6 2.3 0.7 2.8 0.5 3.4 0.7 2.2 0.3 2.1 0.3 <5 <1 <0.5 15 1 <0.5 3  298 300 49.9 110 116 87 <0.1 0.7 170.0 10.5 2.0 54.7 2 19.5 3.1 8.2 1.3 6.3 2.1 0.7 2.7 0.5 3.4 0.7 2.2 0.3 2.0 0.3 <5 <1 <0.5 16 1 <0.5 1  311 460 57.2 115 101 118 0.1 0.5 69.8 5.2 2.0 52.3 2 19.8 2.3 6.6 1.1 6.0 2.2 0.8 2.6 0.5 3.3 0.7 2.1 0.3 2.0 0.3 <5 <1 <0.5 15 1 <0.5 3  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  182  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  84581  200611  249882  249895  84536  84540  84541  84543  84544  Rock Type  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  436498 7504976 clover west basalts 45.31 0.88 13.58 13.58 0.26 5.82 12.32 2.00 0.16 0.07 0.02 0.01 <0.01 5.15 99.16  435180 7505520 clover west basalts 47.98 0.85 15.68 12.40 0.16 7.86 9.32 2.37 0.25 0.07 0.03 0.02 <0.01 3.10 100.10  429172 7557632 Discovery basalts 42.60 0.76 14.55 9.56 0.25 3.97 9.35 1.94 0.60 0.06 0.03 0.02 0.02 16.30 100.00  431933 7548784  442606 7514624 Member Koig Basalts Basalt 47.17 47.01 0.99 0.93 15.31 14.54 12.76 12.97 0.22 0.19 4.28 6.16 11.04 12.85 1.21 1.32 0.09 0.07 0.06 0.08 0.03 0.04 0.02 0.01 0.01 <0.01 5.93 3.58 99.12 99.76  442213 7514256 Member Basalt 47.50 1.01 13.99 14.35 0.21 7.72 10.20 1.22 0.06 0.07 0.06 0.01 0.01 3.28 99.69  441884 7514080 Member Basalt 47.30 0.98 14.19 13.70 0.22 6.06 11.18 1.57 0.14 0.16 0.08 0.01 <0.01 4.32 99.89  441742 7513408 Member Basalt 46.57 0.97 13.87 13.43 0.21 6.16 9.73 0.84 0.05 0.14 0.04 0.01 0.01 7.35 99.38  441320 7512176 Member Basalt 45.43 1.02 14.90 12.23 0.20 4.39 11.38 2.08 0.03 0.08 0.03 0.01 <0.01 7.91 99.71  303 140 48.6 69 110 90 0.1 1.7 95.8 46.6 3.0 60.8 2 20.4 4.0 10.1 1.5 7.5 2.3 0.8 2.8 0.5 3.5 0.7 2.3 0.3 2.3 0.3 <5 <1 <0.5 16 1 <0.5 7  270 290 51.2 137 97 90 0.1 4.3 177.5 59.4 2.0 49.8 1 13.8 3.5 8.0 1.1 5.4 1.7 0.7 1.9 0.4 2.4 0.5 1.6 0.2 1.4 0.9 <5 <1 <0.5 17 1 <0.5 1  243 260 44.4 129 86 66 0.8 20.2 91.7 70.4 1.6 38 1.2 11.9 1.7 4.7 0.7 3.8 1.2 0.5 1.4 0.3 2.1 0.5 1.5 0.2 1.4 0.2 <5 0.4 0.14 13.8 1 0.2 1  297 240 55.0 141 126 91 0.2 1.0 192.0 11.4 2.2 57 1.6 21.2 3.3 8.8 1.4 6.7 2.2 0.8 2.8 0.5 3.6 0.8 2.4 0.4 2.3 0.4 <5 0.3 0.06 16.4 1 0.2 3  346 310 50.1 88 118 100 <0.1 0.3 142.5 11.3 3.0 58 2 22.3 3.2 8.5 1.4 7.0 2.4 0.8 3.1 0.6 3.7 0.8 2.5 0.4 2.4 0.4 <5 <1 <0.5 18 1 <0.5 3  277 270 45.4 92 92 91 0.1 1.4 115.0 33.4 3.0 67.9 2 23.8 4.2 11.2 1.8 8.9 2.8 1.1 3.4 0.6 4.2 0.9 2.7 0.4 2.5 0.4 <5 <1 <0.5 17 1 <0.5 2  274 270 45.4 92 100 99 0.1 0.3 153.0 7.4 3.0 64.7 2 22.0 3.8 10.2 1.6 8.0 2.6 1.0 3.3 0.6 3.8 0.8 2.5 0.4 2.4 0.4 <5 <1 <0.5 17 1 <0.5 2  318 250 47.4 84 120 89 <0.1 0.2 101.0 12.8 3.0 56.2 2 20.9 3.3 8.9 1.4 7.2 2.3 0.9 2.8 0.5 3.7 0.8 2.4 0.3 2.3 0.4 <5 <1 <0.5 17 1 <0.5 1  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  328 320 48.6 106 118 84 <0.1 0.3 141.0 7.0 2.0 69.6 2 21.4 3.0 8.2 1.3 6.8 2.3 0.9 2.9 0.5 3.6 0.8 2.5 0.3 2.4 0.4 <5 <1 <0.5 18 1 <0.5 1  183  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  249515  249516  249518  200688  202930  249877  202918  202924  202925  Rock Type  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  442856 7514880 Member Basalt 45.54 1.06 13.89 11.85 0.19 4.95 8.52 3.57 0.09 0.07 0.03 0.01 0.01 9.24 99.01  442674 7515328 Member Basalt 47.11 1.03 13.88 13.75 0.22 6.70 11.48 0.60 0.07 0.08 0.03 0.02 0.01 4.34 99.33  440391 7512816 Member Basalt 45.30 0.81 15.30 10.97 0.18 6.23 12.50 0.53 0.06 0.06 0.04 0.02 0.01 6.85 98.86  432023 7559392 Windy Basalts 48.30 0.86 13.66 11.23 0.17 5.97 10.52 1.69 0.40 0.08 0.02 0.01 0.01 7.31 100.20  433092 7551616 Windy Basalts 49.56 0.90 13.98 13.01 0.21 8.21 6.95 1.96 1.07 0.08 0.04 0.01 0.02 3.62 99.62  432139 7560224 Windy Basalts 52.86 0.81 13.23 10.39 0.16 7.83 6.27 3.12 0.33 0.10 0.04 0.01 0.01 3.56 98.72  434048 7547616 Wolverine Basalts 46.63 0.74 15.55 10.05 0.23 4.04 15.18 1.15 0.07 0.05 0.03 0.01 <0.01 5.98 99.71  434608 7552736 Wolverine Basalts 47.98 0.95 14.82 13.98 0.20 6.85 9.37 1.60 0.14 0.07 0.04 0.02 0.01 3.28 99.31  434037 7552736 Wolverine Basalts 48.07 1.00 15.86 14.47 0.22 5.61 9.11 1.92 0.09 0.08 0.04 0.01 0.01 3.40 99.90  328 270 47.2 88 94 87 0.0 0.5 60.4 16.1 2.6 56.7 1.8 21.7 3.0 7.0 1.1 6.0 2.2 0.9 2.7 0.5 4.0 0.9 2.5 0.3 2.5 0.3 <5 0.3 0.08 15.9 1 0.2 5  342 280 54.1 88 148 114 0.0 0.6 184.5 9.0 2.6 55.5 1.7 22.2 3.4 8.7 1.3 7.1 2.3 0.9 2.8 0.5 3.9 0.9 2.5 0.4 2.5 0.4 <5 0.3 0.07 18.6 1 0.5 22  275 380 56.1 170 111 84 0.0 0.5 166.5 7.9 1.9 41 1.4 18.1 2.7 6.7 1.0 5.3 1.9 0.7 2.2 0.4 3.1 0.7 2.0 0.3 2.0 0.3 <5 0.2 <0.05 16.6 1 0.2 3  278 140 42.5 73 110 84 0.1 4.3 92.6 55.5 2.0 47.3 2 17.6 3.3 8.5 1.3 6.4 2.1 0.8 2.6 0.5 3.1 0.7 2.0 0.3 1.9 0.3 20 <1 <0.5 15 1 <0.5 <1  300 390 44.7 82 101 94 0.2 22.1 101.5 227.0 3.0 54.4 2 20.4 3.5 8.8 1.3 6.9 2.3 0.6 2.7 0.6 3.4 0.8 2.2 0.3 2.1 0.4 <5 <1 <0.5 13 1 <0.5 2  263 320 42.8 87 83 74 0.1 4.1 56.8 47.1 2.5 62 1.9 16.6 3.1 8.2 1.2 6.3 1.9 0.7 2.4 0.5 3.1 0.7 2.0 0.3 1.9 0.3 <5 0.5 0.08 12.8 1 0.3 2  288 230 55.3 136 120 120 <0.1 0.7 121.5 15.7 2.0 37.8 1 16.2 2.6 6.5 1.0 5.0 1.7 0.7 2.1 0.4 2.7 0.6 1.8 0.3 1.7 0.3 22 <1 <0.5 16 <1 <0.5 1  321 320 49.5 82 120 99 0.1 1.8 109.5 20.7 2.0 48.1 1 20.1 3.3 8.4 1.2 6.2 2.1 0.7 2.7 0.5 3.4 0.7 2.2 0.3 2.1 0.3 <5 <1 <0.5 16 <1 <0.5 1  308 300 52.2 134 68 110 0.1 0.9 116.5 23.7 2.0 48.4 2 20.8 3.3 8.3 1.3 6.6 2.2 0.8 2.5 0.5 3.4 0.8 2.3 0.3 2.2 0.4 <5 <1 <0.5 16 <1 <0.5 1  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  184  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  202947  249861  249862  249873  249874  249876  1000  84529  84531  Rock Type  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  normal basalt  Tholeiitic rhyolite  Tholeiitic rhyolite  Tholeiitic rhyolite  435158 7546512 Wolverine Basalts 46.75 0.72 15.20 10.90 0.19 6.19 10.51 2.96 0.07 0.05 0.04 0.03 0.01 6.23 99.85  432850 7559168 Wolverine Basalts 47.36 0.75 15.04 12.79 0.21 6.94 12.49 1.13 0.09 0.06 0.04 0.03 0.01 3.05 99.97  433623 7559232 Wolverine Basalts 49.64 0.80 14.39 12.18 0.20 5.81 8.82 3.34 0.19 0.06 0.02 0.02 <0.01 4.35 99.79  434765 7559328 Wolverine Basalts 47.04 1.05 15.29 10.65 0.19 6.34 8.53 1.86 0.06 0.09 0.03 0.03 <0.01 7.06 98.22  434352 7559584 Wolverine Basalts 47.53 0.91 15.55 12.30 0.18 3.77 7.81 3.28 0.10 0.08 0.03 0.01 0.01 6.92 98.47  432439 7558864 Wolverine Basalts 47.76 0.92 14.96 11.15 0.21 7.09 10.71 1.68 0.24 0.07 0.03 0.01 0.01 4.11 98.95  445023 7515104  445059 7516832  444299 7516352  Flake  Flake  Flake  70.35 0.28 11.87 5.84 0.04 1.64 1.07 3.06 1.44 0.04 0.00 0.01 0.02 2.81 98.46  78.30 0.20 10.21 2.08 0.10 0.46 2.23 1.47 1.96 0.03 0.02 0.01 0.03 1.45 98.55  73.46 0.19 10.73 8.09 0.03 0.87 0.28 0.36 2.47 0.03 0.02 <0.01 0.03 2.07 98.62  289 360 50.5 138 106 84 0.1 0.7 269.0 12.2 2.0 42.2 1 16.8 2.6 6.5 0.9 4.8 1.6 0.7 2.1 0.4 2.7 0.6 1.7 0.2 1.7 0.2 <5 <1 <0.5 15 1 <0.5 2  274 310 52.1 136 108 86 0.1 0.8 220.0 11.9 1.8 40 1.3 14.8 2.2 6.0 0.9 4.8 1.6 0.6 2.2 0.4 2.7 0.6 1.7 0.3 1.7 0.2 <5 0.4 0.11 15.6 1 0.2 1  284 150 57.0 105 146 92 0.1 2.0 99.6 21.6 1.7 44 1.4 14.6 2.1 5.9 0.9 4.8 1.6 0.6 2.1 0.4 2.8 0.6 1.8 0.3 1.7 0.3 <5 0.4 0.09 14 1 0.2 2  299 240 45.8 107 117 95 0.1 0.4 123.0 10.4 2.4 52 1.8 18.2 2.8 7.7 1.3 6.5 2.1 0.9 2.7 0.6 3.5 0.7 2.2 0.3 2.0 0.3 <5 0.4 0.09 16.5 1 0.2 2  294 240 55.7 121 146 91 0.1 1.3 70.5 12.4 2.4 49 1.6 17.6 2.9 8.3 1.3 6.6 2.0 0.8 2.4 0.5 3.2 0.7 2.1 0.3 2.0 0.3 <5 0.5 0.07 16.4 1 0.3 2  296 250 48.4 111 126 92 0.1 4.3 93.2 51.4 2.4 59 1.8 18.2 2.6 7.3 1.2 6.2 1.9 0.7 2.4 0.5 3.3 0.7 2.2 0.3 2.1 0.3 <5 0.5 0.07 16.5 1 0.3 3  6 10 3.4 248 18 356 0.6 32.9 109.5 245.0 32.0 478 16 134.0 43.9 104.0 14.4 65.5 16.6 4.0 19.1 3.5 24.5 5.3 17.2 2.5 18.4 2.7 5 6.0 1.7 32 6 2 1  8 180 1.4 6 6 39 0.7 36.1 94.6 182.0 10.0 261 8 57.1 21.3 50.0 6.7 29.0 7.3 1.4 8.1 1.5 9.5 2.0 6.6 1.0 6.7 1.0 8 4.0 0.9 16 4 0.7 2  8 140 10.8 5 95 36 1.4 45.7 13.6 233.0 10.0 270 8 58.8 21.6 50.1 6.7 28.6 7.3 1.5 8.3 1.5 9.8 2.2 7.0 1.0 7.0 1.1 <5 4.0 1 17 4 0.7 2  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  185  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  84532  84534  249520  84528  Rock Type  Tholeiitic rhyolite  Tholeiitic rhyolite  Tholeiitic rhyolite  Tholeiitic rhyolite  77.05 0.11 11.49 2.13 0.02 0.47 0.59 3.38 1.98 0.01 0.02 0.01 0.05 1.55 98.85  200687 Ti-enriched Al-depleted basalt 432195 7559808 Patch Lake Mafics 41.69 3.45 13.29 15.15 0.24 7.54 8.35 0.27 2.32 0.29 0.05 0.02 0.10 5.98 98.75  200694 Ti-enriched Al-depleted basalt 431903 7558768 Patch Lake Mafics 39.40 2.22 6.83 19.41 0.20 17.43 6.75 0.12 0.05 0.21 0.20 <0.01 <0.01 6.73 99.56  UTME UTMN  444251 7516016  443735 7515408  446542 7518416  444998 7516672  Suite  Flake  Flake  Flake  Flake  SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total  76.59 0.32 11.27 3.44 0.04 0.61 0.73 4.03 0.93 0.04 0.02 0.01 0.02 1.30 99.33  73.92 0.17 11.81 4.30 0.04 0.76 1.26 4.63 1.28 0.03 0.02 0.01 0.03 0.99 99.24  74.25 0.32 10.93 4.68 0.08 2.06 1.39 0.73 2.18 0.02 <0.01 0.02 0.04 2.26 98.96  V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  25 200 3.7 7 6 31 0.2 17.4 57.6 143.0 10.0 272 9 68.7 21.6 50.2 6.6 28.1 7.0 1.3 8.2 1.5 10.8 2.4 7.9 1.2 8.0 1.2 <5 4.0 1.1 16 3 0.7 2  52 180 3.6 5 5 40 0.1 13.4 69.9 322.0 11.0 290 9 62.8 22.7 54.7 7.4 31.0 7.9 1.4 8.3 1.5 10.1 2.3 7.4 1.1 7.7 1.2 <5 4.0 1.1 15 3 0.7 2  10 10 1.9 5 <5 234 0.4 35.8 43.8 369.0 31.7 529 16 152.0 46.6 114.5 15.8 70.0 17.6 4.0 20.0 3.7 26.9 6.0 18.0 2.6 18.0 2.6 <5 5.9 1.3 30.9 4 1.8 2  <5 150 1.2 5 6 72 0.3 37.4 31.3 444.0 73.0 430 18 173.0 67.1 151.0 19.0 73.2 18.0 2.2 19.7 3.7 25.3 5.7 19.4 2.9 20.5 3.0 <5 13.0 3.2 28 9 4.4 2  501 370 64.5 244 200 175 0.3 40.9 192.0 925.0 26.0 160 5 31.6 23.9 61.2 8.5 37.6 8.3 2.7 8.1 1.3 6.6 1.3 3.4 0.4 2.8 0.4 11 2.0 0.5 25 2 1.5 <1  331 1440 96.2 759 188 104 0.1 1.6 20.0 8.5 17.0 124 4 20.8 9.5 25.5 3.5 17.2 4.6 1.4 5.0 0.8 4.3 0.8 2.1 0.2 1.7 0.2 <5 1.0 <0.5 16 2 0.8 1  186  84533  84537  84538  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  444112 7516032  443002 7515792  443331 7515296  bend High Ti bend High Ti bend High Ti 51.46 1.44 12.64 16.09 0.21 4.72 7.21 2.55 0.32 0.18 0.01 0.01 0.02 2.56 99.43  48.27 1.49 14.50 17.33 0.28 5.14 6.04 3.52 0.16 0.12 <0.01 0.01 0.01 3.25 100.10  48.12 1.50 13.82 17.74 0.22 5.80 7.34 2.26 0.15 0.10 <0.01 0.01 0.01 2.97 100.05  378 90 45.5 47 98 128 0.2 7.4 109.0 104.0 6.0 134 4 46.2 10.2 26.4 3.8 18.2 5.4 1.6 6.4 1.2 7.9 1.7 5.2 0.8 5.0 0.8 <5 1.0 <0.5 20 1 <0.5 1  419 70 54.3 44 126 144 0.1 1.3 67.9 29.6 4.0 86.7 3 31.7 4.6 12.4 1.9 10.0 3.4 1.1 4.3 0.8 5.5 1.2 3.6 0.5 3.5 0.5 <5 <1 <0.5 16 1 <0.5 2  438 70 49.5 41 103 137 0.1 0.9 88.4 20.1 4.0 84.4 3 31.1 4.8 13.1 2.0 10.4 3.4 1.1 4.3 0.8 5.4 1.2 3.5 0.5 3.4 0.5 <5 <1 <0.5 19 1 <0.5 1  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  84539  249538  249899  249900  249863  249864  249865  249875  200686  Rock Type  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  UTME UTMN  442749 7515680  441271 7504672  Suite  Bend High Ti Boston Ti  428999 7556944 Discovery basalts 52.68 1.45 16.66 10.12 0.16 4.78 2.97 2.71 0.82 0.12 0.04 0.02 0.02 6.79 99.32  433660 7559232 Doris Basalts 52.17 1.43 12.43 14.36 0.13 3.17 5.48 3.54 0.06 0.22 <0.01 0.02 <0.01 6.43 99.43  433603 7558960 Doris Basalts 47.93 1.59 14.06 16.12 0.25 3.11 5.51 3.35 0.04 0.27 <0.01 0.01 0.02 6.99 99.25  433396 7558512 Doris Basalts 56.02 1.33 11.94 15.17 0.20 2.07 4.24 3.51 0.10 0.31 <0.01 0.02 0.02 4.57 99.49  433823 7559040 Doris Basalts 48.49 1.22 10.84 13.81 0.34 2.56 6.84 2.33 0.97 0.20 <0.01 0.01 0.02 11.20 98.81  432383 7559392 Patch Lake Mafics 50.14 1.58 12.83 10.79 0.24 2.31 9.58 2.88 0.92 0.12 <0.01 0.01 0.01 8.73 100.15  409 80 45.8 58 93 154 1.1 19.2 107.0 104.0 2.9 79 2.1 21.5 3.9 10.3 1.6 7.6 2.4 0.9 3.2 0.6 3.7 0.9 2.5 0.4 2.2 0.3 6 0.3 0.08 21.8 1 0.2 2  109 10 27.9 6 29 112 0.1 0.6 54.3 10.2 4.6 114 3.7 38.5 7.6 18.5 2.7 13.4 4.2 1.5 5.3 1.1 6.9 1.5 4.5 0.6 4.3 0.7 <5 1.2 0.27 19.8 1 0.4 2  127 10 34.7 5 9 153 0.1 0.3 72.0 9.5 4.6 140 4.4 30.4 6.4 16.8 2.5 12.1 3.5 0.9 4.6 0.9 6.0 1.3 4.3 0.6 4.4 0.7 <5 1.6 0.48 22.9 1 0.5 2  58 10 23.1 9 49 148 0.1 1.2 98.0 46.5 5.4 131 4 44.6 7.4 20.2 2.9 14.7 4.8 1.8 6.0 1.2 8.0 1.7 5.5 0.7 5.2 0.8 <5 1.3 0.29 19.6 1 0.5 2  94 10 25.6 5 23 121 0.4 21.2 93.9 133.5 3.9 104 3.3 35.3 6.7 17.1 2.5 12.2 3.9 1.4 4.8 1.0 6.5 1.3 4.2 0.6 4.0 0.6 <5 1.1 0.28 19 1 0.3 <1  376 60 37.2 43 96 112 0.3 21.8 60.3 160.0 5.0 94.3 3 35.2 7.4 19.0 2.7 13.2 4.3 1.2 5.0 0.9 5.9 1.3 3.9 0.6 3.6 0.5 55 1.0 <0.5 17 1 <0.5 <1  SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total  46.63 1.41 13.76 16.79 0.23 5.99 9.08 2.09 0.15 0.13 0.02 0.01 <0.01 3.63 99.93  43.19 1.48 13.12 13.94 0.21 5.52 8.45 2.02 0.40 0.11 0.05 0.01 0.01 9.82 98.33  427635 7557104 Discovery basalts 53.38 1.85 15.50 5.62 0.16 1.87 7.46 5.94 0.27 0.33 0.01 0.03 0.02 7.10 99.53  V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  426 60 50.8 42 86 117 0.1 1.5 143.0 35.7 4.0 78 2 30.4 4.5 12.4 2.0 9.9 3.4 1.3 4.3 0.8 5.2 1.1 3.4 0.5 3.3 0.5 <5 <1 <0.5 19 1 <0.5 3  340 150 52.8 97 113 111 0.2 1.6 104.5 8.4 7.2 86 2.6 23.1 6.6 19.5 2.4 11.8 3.2 1.0 4.1 0.7 4.4 1.0 2.8 0.4 2.7 0.4 <5 0.8 0.13 17 1 0.5 34  192 120 42.6 145 104 95 0.5 6.8 202.0 113.0 11.3 183 4.7 23.4 10.4 29.7 4.4 20.6 5.6 1.6 5.6 0.8 4.8 0.9 2.3 0.3 1.8 0.3 <5 0.7 0.18 22 2 0.8 2  187  Appendix C: Major oxide and Trace element concentrations by XRF and ICP-MS (ALS Chemex) for samples from the Hope Bay Greenstone Belt Sample  200689  200693  200695  202920  202921  202928  202929  Rock Type  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  Ti-enriched basalt  432139 7559312 Patch Lake Mafics 52.69 1.53 14.89 10.99 0.20 2.80 6.32 2.67 1.20 0.11 0.01 0.01 0.02 6.70 100.15  432233 7558880 Patch Lake Mafics 57.43 1.61 12.91 7.68 0.15 1.49 7.28 1.87 1.81 0.12 0.01 0.01 0.05 7.69 100.10  432500 7556688 Patch Lake Mafics 48.68 1.53 13.57 16.88 0.22 5.67 7.05 2.85 0.12 0.11 <0.01 0.02 0.02 2.68 99.40  432982 7547952 Patch Lake Mafics 45.53 1.42 13.05 14.01 0.29 2.68 10.89 2.31 0.07 0.13 0.01 0.01 <0.01 9.48 99.89  432510 7548208 Patch Lake Mafics 48.00 1.91 11.57 18.35 0.24 3.58 6.37 1.95 0.28 0.20 <0.01 0.01 0.01 7.52 100.00  433673 7552864 Patch Lake Mafics 43.88 1.54 12.91 14.37 0.22 2.81 10.20 3.03 0.05 0.14 0.01 0.01 0.01 10.35 99.53  433764 7551840 Patch Lake Mafics 47.39 1.52 15.65 15.59 0.26 4.63 6.51 1.94 0.30 0.12 0.01 0.01 0.02 5.89 99.84  400 120 46.8 65 112 102 0.3 31.5 51.6 276.0 4.0 80.7 3 28.7 4.0 10.8 1.7 8.8 3.1 1.1 3.8 0.7 4.9 1.1 3.3 0.5 3.3 0.5 105 <1 <0.5 19 2 <0.5 <1  359 80 36.8 47 92 73 0.7 48.0 43.0 409.0 5.0 104 3 34.5 7.3 18.6 2.6 12.7 4.0 1.2 4.8 0.9 5.8 1.2 3.8 0.5 3.6 0.5 <5 1.0 <0.5 20 2 <0.5 1  420 50 48.8 38 115 132 0.1 1.2 166.0 31.3 4.0 84.8 3 32.7 4.8 12.8 1.8 10.0 3.1 1.2 4.0 0.8 5.3 1.1 3.7 0.5 3.6 0.5 <5 <1 <0.5 18 1 <0.5 1  385 70 43.5 41 102 395 0.1 0.6 85.7 32.3 4.0 79.8 3 32.5 5.3 12.8 1.9 9.7 3.0 1.1 3.8 0.8 5.0 1.2 3.7 0.6 3.5 0.6 <5 <1 <0.5 17 <1 <0.5 1  291 40 48.1 8 112 152 0.8 2.9 102.5 23.9 11.0 127.5 4 41.3 13.2 31.0 4.4 21.0 5.9 1.5 6.7 1.2 7.5 1.6 4.6 0.7 4.3 0.7 <5 1.0 <0.5 19 <1 0.7 1  355 80 41.2 38 82 136 <0.1 0.4 124.5 14.6 5.0 92.8 3 34.1 7.0 17.6 2.6 13.2 3.8 1.2 4.7 0.9 5.8 1.3 3.8 0.6 3.6 0.6 6 1.0 <0.5 17 <1 <0.5 1  390 160 46.9 82 87 122 0.2 6.9 128.0 66.0 4.0 83.9 3 33.5 5.8 15.6 2.4 11.7 3.7 1.5 4.4 0.9 5.7 1.2 3.6 0.5 3.6 0.6 <5 <1 <0.5 21 <1 <0.5 1  UTME UTMN Suite SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 Cr2O3 SrO BaO LOI Total V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Pb Th U Ga Sn Ta W  188  APPENDIX D: High Resolution Trace Element Abundances of Samples From the Hope Bay Greenstone Belt, (PCIGR)  189  Appendix D: Trace element concentrations by HR-ICP-MS (PCIGR) for samples from the Hope Bay Greenstone Belt Sample no.1 84536 Member Suite basalts  84541 Member basalts  84544 Member basalts  202915 Boston Basalt  84545 Clover east basalts  84572 Clover east basalts  84574 Clover east basalts  84573 84557 Clover Lake Clover west Suite basalts  Rock Type  Normal Basalt  Normal Basalt  Normal Basalt  Normal Basalt  Normal Basalt  Normal Basalt  LREE Basalt Rhyolite  Normal Basalt  Northing Easting Sc  442606 7514639 36.5  441884 7514093 41.4  441320 7512181 38.0  441033 7504174 42  439452 7507669 32.6  438902 7507363 32.5  438811 7506770 25.6  438196 7506733 2.788  436704 7502763 41.5  V  351  314  373  318  282  242  211.5  6.8  343  Cr  256  242  172  203  221  893  104  174  56  Co  50.3  47  50  48.7  49.3  60.3  33.9  1.2  52.0  Ni  97  90  84.2  91.4  116  290  89.4  3.5  64.1  Cu  104.4  87  118.0  62.5  107.2  76  61.3  3.4  109  Zn  89  111  100  64.6  77  85  88  32  112  Cs  0.016  0.045  0.03  0.77  0.62  0.105  0.69  1.9  0.150  Rb  0.202  1.58  0.173  14.10  10.99  0.68  11.88  95  2.3  Sr  153  129  108  66  91  103  342  42.5  110  Ba  9.77  35.7  13.9  108  94  11.4  204.1  681  44.7  Nb  2.77  3.7  3.04  2.9  2.30  2.0  6.12  3.0  4.42  Zr  36.4  77  49.8  44.2  42  23.1  111  55  58.5  Hf  1.023  1.9  1.28  1.163  1.15  0.74  2.76  2.1  1.546  Y  18.8  24.0  18.7  12.6  14.0  13.71  15.8  4.17  23.8  La  3.06  4.18  3.20  2.72  2.51  2.18  11.1  12.90  5.43  Ce  8.2  11.50  8.62  7.4  6.40  5.82  25.0  25.5  14.3  Pr  1.26  1.747  1.33  1.11  0.97  0.893  3.22  2.72  2.1  Nd  6.3  8.49  6.57  5.30  4.75  4.44  13.3  8.95  9.7  Sm  2.04  2.62  2.103  1.58  1.52  1.40  2.94  1.64  2.8  Eu  0.791  0.98  0.773  0.56  0.540  0.494  0.94  0.190  0.92  Gd  2.73  3.47  2.80  1.94  2.06  1.956  2.979  1.20  3.5  Tb  0.49  0.611  0.50  0.348  0.369  0.350  0.474  0.172  0.61  Dy  3.40  4.34  3.45  2.13  2.5  2.428  3.01  0.835  4.5  Ho  0.74  0.93  0.75  0.52  0.56  0.526  0.618  0.140  0.96  Er  2.10  2.75  2.20  1.55  1.64  1.52  1.74  0.357  2.8  Tm  0.308  0.398  0.328  0.236  0.24  0.219  0.251  0.048  0.386  Yb  1.96  2.62  2.19  1.54  1.61  1.51  1.67  0.32  2.6  Lu  0.291  0.408  0.341  0.24  0.25  0.210  0.253  0.045  0.383  Pb  0.672  0.517  0.290  0.355  0.223  0.347  2.30  2.391  0.406  Th  0.242  0.339  0.275  0.272  0.237  0.174  1.4  0.38  0.48  U  0.047  0.062  0.051  0.048  0.043  0.0329  0.279  1.28  0.078  Li  9.4  11.7  11.8  45.9  20.5  16.2  11.5  8.4  26.9  Ga  15.3  15.4  15.7  15.9  13.0  11.31  18.33  19.3  13.3  Mo  0.465  0.47  0.38  0.22  0.20  0.41  0.38  1.037  0.434  Cd  0.087  0.17  0.146  0.06  0.073  0.058  0.11  0.04  0.094  Sn  0.38  0.43  0.64  0.31  0.275  0.358  0.543  0.147  0.48  Sb  0.116  0.032  0.018  0.378  0.288  0.12  0.476  0.83  0.263  Ta  0.159  0.222  0.167  0.190  0.134  0.113  0.407  0.29  0.267  W  0.056  0.127  0.049  0.117  0.062  0.042  0.109  0.229  0.35  Bi  0.0075  0.00559  0.006  0.0109  0.0046  0.0075  0.0136  0.168  0.00526  190  Appendix D: Trace element concentrations by HR-ICP-MS (PCIGR) for samples from the Hope Bay Greenstone Belt Sample no.1 84576 84577 84579 84581 200611 84502 Clover west Clover west Clover west Clover west Clover west Flake Lake Suite basalts basalts basalts basalts basalts Suite  84514 Flake Lake Suite  84589 Flake Lake Suite  84591 Flake Lake Suite  Rock Type  Normal Basalt  Normal Basalt  Normal Basalt  Normal Basalt  Normal Basalt  Felsic  Felsic  Felsic  Felsic  Northing Easting Sc  437337 7505892 39.0  437045 7505239 57  436006 7505604 51.9  436498 7504990 38  435180 7505521 36.6  445855 7519179 6.74  446046 7518893 0.77  445066 7513292 0.246  444650 7515305 1.79  V  383  300  300  326  308  40.0  9.4  1.59  16.1  Cr  82.6  290  454  107  258  121.1  129  88  98  Co  57.0  56  58.3  50.5  54  8.05  5.0  0.477  4  Ni  63.7  112  108.3  66.1  131  5.43  8.2  3.0  4  Cu  124.4  116  92.4  93  88  15.17  16  7.6  14.3  Zn  98.1  82  115  92  77  93  27  20.6  109  Cs  0.203  0.14  0.08  0.097  0.14  0.21  0.0383  0.118  0.421  Rb  3.70  5.0  0.382  1.83  4.7  12.17  3.90  3.4  31.3  Sr  196.7  106  72.7  99  185.3  75  232  38.4  46.2  Ba  36.6  31.7  6.8  48  62  147  63.8  29.8  156  Nb  4.4  2.4  2.333  3.58  2.395  14.5  23  40.5  28.8  Zr  59  56  54.9  35  28.0  388  497  314  371  Hf  1.75  1.51  1.463  0.94  0.89  10.94  13.9  10.8  10.8  Y  25.1  23.8  23.2  17.9  13.81  101  116  64  102  La  6.05  4.29  2.89  3.80  3.65  19.4  28  63.0  61.1  Ce  14.95  11.15  8.619  9.9  9.0  48.1  71  137  149  Pr  2.13  1.656  1.38  1.44  1.26  7.3  9.7  17.7  19.7  Nd  10.27  8.08  7.33  6.8  6.0  34.0  44  72.8  82  Sm  2.98  2.56  2.55  2.08  1.68  10.1  11.8  14.8  17.9  Eu  0.95  0.931  1.003  0.76  0.70  2.1  3.0  1.7  3.2  Gd  3.75  3.52  3.46  2.63  2.15  13.2  14.6  14.5  17.7  Tb  0.656  0.629  0.63  0.471  0.372  2.4  2.7  2.3  2.9  Dy  4.53  4.24  4.24  3.3  2.53  16.5  18.3  14.1  18.6  Ho  0.97  0.912  0.90  0.70  0.54  3.74  4.20  2.92  4.0  Er  2.74  2.736  2.663  2.1  1.55  11.4  13.2  8.43  12.1  Tm  0.415  0.384  0.394  0.300  0.221  1.75  2.04  1.2  1.8  Yb  2.61  2.63  2.62  1.91  1.43  11.9  13.89  8.43  12.2 1.9  Lu  0.381  0.412  0.408  0.28  0.205  1.9  2.16  1.288  Pb  0.69  0.421  0.467  0.43  0.8  2.93  1.86  1.8  1.9  Th  1.10  0.07  <lod  0.346  0.31  3.7  5.16  10.6  8.7  U  0.120  0.02  <lod  0.067  0.061  0.831  1.149  0.783  1.642 17.4  Li  17.1  31.0  31.5  19.5  17.8  <lod*  0.03  <lod  Ga  16.41  16.1  15.5  14.4  16.2  15.52  22  13.2  16.2  Mo  0.49  1.0  0.800  0.41  0.3373  2.20  1.8  3.38  5.41  Cd  0.14  0.026  0.165  0.131  0.060  0.17  0.07  0.062  0.158  Sn  0.49  0.3  0.168  0.447  0.33  1.90  1.1  0.93  2.44  Sb  0.73  0.17  1.37  0.29  0.17  0.12  0.223  0.264  0.75  Ta  0.299  0.171  0.177  0.197  0.143  0.77  0.83  1.8  1.49  W  0.364  0.13  0.063  0.221  0.10  0.232  0.262  0.35  0.28  Bi  0.154  <lod  <lod  0.0112  0.0125  0.06  0.078  0.07  0.045  191  Appendix D: Trace element concentrations by HR-ICP-MS (PCIGR) for samples from the Hope Bay Greenstone Belt Sample no.1 202910 Suite  Ti Enriched Al Depleted Basalt 436986 7532167 41.3  Ti Enriched Basalt  Ti Enriched Basalt  Ti Enriched Basalt  Dacite  Dacite  Dacite  Ti Enriched Basalt  444625 7514723 40.9  443962 7515325 36.6  443331 7515307 42.5  434569 7505768 7.59  433606 7505416 4.7  434808 7505652 4.74  433764 7551849 39.5  202940 Patch Lake Mafics Ti Enriched Al Depleted Basalt 434297 7550413 44  Gas Cache  Rock Type Northing Easting Sc  84515  84516  84538  84585 Koignuck Bend Basalt Bend Basalt Bend Basalt Suite  84586 Koignuck Suite  200632 Koignuck Suite  202929 Patch Lake Mafics  V  496  456  428  465  84  78.5  87  427  526  Cr  181.8  54  52  51  73  73.6  76.1  140  242  Co  60.1  49.8  45.0  49.0  23  13.00  14.6  47  69.6 156.9  Ni  150.1  40.6  30.0  35  44  21.6  38  78  Cu  268.9  102  100.1  94  28  27  32  77  199  Zn  192  222  137  141  86  78.8  77.6  104  231 0.388  Cs  1.467  0.193  0.03  0.046  0.86  0.530  0.966  0.173  Rb  25.3  2.1  1  0.93  27  34.6  24.3  7.4  24.71  Sr  230  165  142  91.2  27.0  140  219  130  258  Ba  262  14.4  13.8  18.27  129.8  171.3  194  73  1889  Nb  24.28  6.857  4.47  4.5  5.7  6.89  5.61  4.5  24.6  Zr  187  122  74.5  45.6  153  167  169.8  88  190.9  Hf  4.8  3.1  1.93  1.36  3.75  4.3  4.2  2.22  4.78  Y  31.2  42  28.2  28.0  10.8  12.62  9.5  30.8  34.5  La  28.75  9.64  4.99  4.507  19.2  16.0  16.7  5.66  30.2  Ce  71  25.0  13.4  12.05  35.9  33.0  30.8  15.18  74  Pr  9.60  3.56  2.03  1.83  3.85  3.74  3.46  2.226  10.0  Nd  42.1  16.1  10.1  9.3  14.0  13.9  12.5  10.54  43.5  Sm  9.16  4.7  3.18  3.01  2.7  2.72  2.38  3.353  9.4  Eu  2.76  1.405  1.20  1.00  0.767  0.792  0.749  1.31  3.0  Gd  8.3  5.92  4.22  3.985  2.41  2.57  2.15  4.30  8.6  Tb  1.17  1.07  0.75  0.718  0.350  0.384  0.320  0.776  1.25  Dy  6.7  7.26  5.2  4.9  1.97  2.31  1.9  5.39  7.2  Ho  1.22  1.632  1.12  1.05  0.401  0.460  0.365  1.156  1.35  Er  3.09  4.73  3.32  3.1  1.10  1.29  0.98  3.42  3.47  Tm  0.419  0.72  0.479  0.446  0.158  0.189  0.132  0.501  0.472  Yb  2.56  4.611  3.12  2.8  1.06  1.25  0.86  3.21  2.9  Lu  0.358  0.71  0.493  0.40  0.174  0.193  0.135  0.493  0.417  Pb  2.60  1.517  1.50  0.580  1.27  1.8  2.0  0.539  3.00  Th  3.1  1.03  0.39  0.37  2.6  3.0  3.0  0.41  2.7  U  0.590  0.181  0.083  0.070  0.508  0.627  0.610  0.076  0.507  Li  14.6  16.6  15.0  14.9  42  8.5  17.6  38.7  25.6  Ga  21.86  17.5  17  15.4  18  17.09  18.14  18.9  25.1  Mo  2.41  0.62  0.49  0.364  6.21  1.59  4.6  0.36  2.90  Cd  0.30  0.206  0.158  0.137  0.0429  0.0577  0.134  0.052  0.097  Sn  0.4988  0.82  0.326  0.401  0.42  0.53  0.886  0.507  1.014  Sb  0.20  0.085  0.106  0.04  0.25  0.064  0.11  0.045  0.286  Ta  1.19  0.36  0.240  0.24  0.49  0.53  0.40  0.303  1.12  W  0.154  0.217  0.094  0.074  0.58  0.31  0.24  0.103  0.20  Bi  0.0205  0.060  0.023  0.0061  0.0179  0.0307  0.051  0.0119  0.031  192  Appendix D: Trace element concentrations by HR-ICP-MS (PCIGR) for samples from the Hope Bay Greenstone Belt Sample no.1 202943 Patch Lake Suite Mafics  84626 Windy Basalts  202930 Windy Basalts  84521 Windy Felsics  84551 Windy Felsics  Rock Type  Ti Enriched Basalt  Normal Basalt  Normal Basalt  Felsic  Northing Easting Sc  433968 7551527 37.4  433898 7550638 35.4  433092 7551626 52  438992 7514291 5.8  202931 Windy Felsics  202918 Wolverine Basalts  200649 Wolverine Basalts  Felsic/sedim felsic entry  Normal Basalt  Normal Basalt  439610 7511094 1.56  434048 7547623 30.6  436630 7545657 50.9  432493 7551376 7.7  V  445  305  284  91  41.0  84.4  301  280.6  Cr  106  376  389.5  120  44.3  87.8  201  360  Co  42.8  49  42.5  15  6.1  8.0  54.8  54.7 165.8  Ni  53.5  108  72.0  41  8.0  24.8  128.9  Cu  92  88  81.6  26  6.32  38  104  114.6  Zn  111  78  75.7  60  47.5  29.7  103.5  66.43 0.526  Cs  0.046  0.098  0.105  0.57  0.500  0.806  0.043  Rb  1.20  8.7  23.48  26  31.3  24.9  0.511  29.1  Sr  136  73  94.8  332  257  81.0  120  94.4  Ba  21.0  41.8  201  356  215  282  17.7  113.1  Nb  4.204  2.68  2.395  5.90  3.97  2.93  1.874  1.96  Zr  80  53  53  145.20  118  128  37  44.9  Hf  2.01  1.31  1.458  3.59  3.07  3.26  0.977  1.314  Y  25.55  14.3  22.44  13.8  6.27  7.76  13.2  21.3  La  4.46  3.52  4.03  24.6  9.90  11.9  2.18  2.94  Ce  12.0  9.24  10.66  51  21.44  21.9  6.2  8.1  Pr  1.82  1.33  1.58  5.5  2.32  2.58  0.95  1.236  Nd  9.0  6.32  7.70  20.4  8.8  9.9  4.70  6.35  Sm  2.86  1.82  2.466  3.7  1.8  2.0  1.49  2.091  Eu  1.022  0.628  0.725  1.06  0.523  0.684  0.609  0.747  Gd  3.82  2.30  3.35  3.15  1.54  1.89  2.04  2.942  Tb  0.69  0.401  0.592  0.453  0.210  0.263  0.353  0.538  Dy  4.75  2.68  3.984  2.60  1.2  1.44  2.68  3.71  Ho  1.06  0.582  0.87  0.52  0.238  0.277  0.58  0.817  Er  3.11  1.69  2.55  1.4  0.63  0.77  1.694  2.45  Tm  0.444  0.260  0.36  0.202  0.094  0.107  0.244  0.348  Yb  2.96  1.71  2.54  1.3  0.63  0.698  1.59  2.42 0.392  Lu  0.46  0.263  0.380  0.203  0.094  0.111  0.241  Pb  0.52  0.58  0.479  3.23  2.2  0.621  0.63  1.080  Th  0.377  0.255  0.0380  4.5  2.38  2.9  0.173  0.035  U  0.071  0.047  0.0395  0.92  0.598  0.425  0.041  <lod  Li  22.3  35.0  8.9  1.33  0.80  15.9  9.4  24.8  Ga  17.7  12.9  12.86  20  13.23  18.18  14.167  15.79  Mo  0.36  0.30  0.30  2.93  0.749  1.65  0.333  0.474  Cd  0.130  0.04  0.06  0.063  0.072  0.0341  0.151  0.095  Sn  0.316  0.29  0.0026  0.450  0.428  0.50  0.327  0.26  Sb  0.043  0.05  <lod  0.07  0.200  0.1018  0.125  0.09  Ta  0.242  0.152  0.170  0.504  0.315  0.219  0.110  0.1  W  0.124  0.17  0.0257  0.30  0.08  0.20  0.066  0.012  Bi  0.00384  0.006  <lod  0.10  0.055  0.031  0.012  <lod  193  APPENDIX E: Results and Discussion of QA/QC  194  Analysis of Standards The standards that were included in the regular sample shipments and the results of the analysis are presented in Table E.1. Overall the results are within acceptable values of error with some elements showing reproducibility problems. The elements that appear to have problems being reproduced include some of the transition metals including Cu, Zn, Ni and Co. These elements often contaminate samples during the crushing and pulverising process.  A Discussion on Comparison of PCIGR and ALS Chemex Analysis A subset of samples analyzed by ALS Chemex was selected to undergo further geochemical and isotopic determination at the Pacific Centre for Isotopic and Geochemical Research (PCIGR). For methods of analysis of the labs refer to Appendix B. This created duplicate analysis of 35 samples and can examine the (accuracy and precision) reliability and reproducibility of analysis. Binary plots of selected elements with concentration at each lab plotted on the axis and are found in Figure E.1. The majority of elements have high correlations (R2>0.9), with the exception of Pb, Th, Sn, U, W. Lu, Mo, Hf and Ga. Some of these elements are close to a R2 of 0.9 and include Lu, Hf and Pb. Concentrations of the Uranium series elements (U, Pb, Th) are all close to, or fall below the detection limit for the ALS Chemex analysis. This would explain the low correlation of U and Th but does not account for the negative correlation in Pb. The high values of Pb and W in the ALS analysis compared to low concentration in the PCIGR analysis suggest Pb and W contamination ALS Chemex samples after the crushing and pulverization (Figure E.1). A number of elements from ALS Chemex show  195  low resolution which results in a “step effect” and includes the elements W, Sn, Pb, U, Th, Lu and Hf. Another effect that is observed in the data from both labs is that of samples with extremely high REE concentrations correlate poorly between the two labs. It may be related to instrumental or dissolution problems of refractory minerals (such as zircon) contained in this rock These are samples from the Flake Lake Suite which is a highly fractionated rhyolite and in Chapter 3 has been shown to be isotopically and geochemical inhomogeneous.  196  Table E.1: Standards processed at ALS Chemex Standard BAS-1 Sample Sample % error 249887 n=4 249524 SiO2 53.30 52.51 1.48 51.83 TiO2 1.30 1.36 4.62 1.35 Al2O3 15.40 15.34 0.39 15.47 Fe2O3 10.70 11.11 3.83 10.75 MnO 0.15 0.14 6.67 0.14 MgO 7.35 7.38 0.41 6.91 CaO 7.84 7.99 1.91 7.99 Na2O 3.20 3.13 2.19 3.04 K2O 0.54 0.55 1.85 0.51 P2O5 0.19 0.23 21.05 0.20 Total 100.20 99.77 0.43 98.21 V Cr Co Ni Cu Zn Cs Rb Sr Ba Nb Zr Hf Yb La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Y Lu Pb Th U Ga Sn Ta  155.00 220.00 47.00 169.00 61.00 104.00 0.12 6.70 436.00 167.00 7.80 91.00 2.30 1.40 8.80 20.00 2.80 13.00 3.50 1.30 3.70 0.57 3.10 0.61 1.50 0.22 17.00 0.20 2.00 0.83 0.32 19.00 1.00 0.48  164.00 240.00 51.40 191.00 55.00 107.00 0.10 6.60 502.00 180.50 7.60 87.00 2.40 1.41 9.40 20.90 2.92 13.40 3.42 1.24 3.33 0.51 3.12 0.60 1.61 0.21 16.00 0.20 <DL 0.83 0.31 20.40 1.00 0.50  5.81 9.09 9.36 13.02 9.84 2.88 16.67 1.49 15.14 8.08 2.56 4.40 4.35 0.71 6.82 4.50 4.29 3.08 2.29 4.62 10.00 10.53 0.65 1.64 7.33 4.55 5.88 0.00 n/a 0.00 3.13 7.37 0.00 4.17  176.00 240.00 49.50 187.00 58.00 81.00 0.09 5.60 457.00 176.50 6.90 84.00 2.40 1.40 9.30 21.60 2.96 13.20 3.52 1.25 3.28 0.57 3.15 0.60 1.66 0.20 14.30 0.21 <DL 0.85 0.32 19.50 1.00 0.50  % error 2.76 3.85 0.45 0.47 6.67 5.99 1.91 5.00 5.56 5.26 1.99  Standard P-1 n=5 70.96 0.38 14.10 3.90 0.08 1.11 3.49 3.80 2.12 0.08 100.56  Sample 249542 69.08 0.35 14.46 3.66 0.07 1.02 3.27 3.61 1.98 0.07 98.16  % error 2.65 7.89 2.55 6.15 12.50 8.11 6.30 5.00 6.60 12.50 2.39  13.55 9.09 5.32 10.65 4.92 22.12 25.00 16.42 4.82 5.69 11.54 7.69 4.35 0.00 5.68 8.00 5.71 1.54 0.57 3.85 11.35 0.00 1.61 1.64 10.67 9.09 15.88 5.00 n/a 2.41 0.00 2.63 0.00 4.17  58.20 149.20 6.20 none 15.50 44.00 1.22 50.40 256.00 724.00 3.78 126.00 3.76 2.46 13.20 28.00 3.36 13.00 2.92 0.78 3.12 0.52 3.34 0.72 2.10 0.35 22.80 0.40 10.20 4.38 1.48 15.00 2.44 0.30  57.00 130.00 7.60 6.00 8.00 52.00 0.98 45.00 218.00 704.00 3.40 133.00 3.80 2.22 11.00 25.90 2.70 11.20 2.48 0.77 3.01 0.50 3.08 0.70 2.13 0.31 18.30 0.33 11.00 4.18 1.27 14.20 2.00 0.30  2.06 12.87 22.58 n/a 48.39 18.18 19.67 10.71 14.84 2.76 10.05 5.56 1.06 9.76 16.67 7.50 19.64 13.85 15.07 1.28 3.53 3.85 7.78 2.78 1.43 11.43 19.74 17.50 7.84 4.57 14.19 5.33 18.03 0.00  197  2000  200  70  Ba  100  500  Slope= 0.9644 Int= 0.1646 R2=.98  50  ALS CHEMEX  1000  Co  60  Slope= 1.055 Int= -1.405 2 R =.98  150 ALS CHEMEX  ALS CHEMEX  Ce  Slope= 0.9195 Int= 14.39 R2=.99  1500  40 30 20  50  10  0  0  0 0  500  1000 PCIGR  1500  2000  0  50  100 PCIGR  150  0  200  2 1000  30 40 PCIGR  50  60  70  Cu Slope= 1.040  Slope= 0.9111 Int= 0.03224 R2=.98  Slope= 1.085 Int= 17.68 r'=.97  Int= 2.214 R2=.98  600  400  ALS CHEMEX  200  ALS CHEMEX  ALS CHEMEX  20  300  Cs  Cr  800  10  1  100  200  0 200  400 PCIGR  600  800  0  1 PCIGR  0  2  Eu  Slope= 0.8.034 Int= 4.411 R2=.7  Slope= 0.8760 Int= 0.5.939 R2=.86  15 ALS CHEMEX  15  300  Hf  Slope= 1.005 Int= 0.03287 R2=.93  3 ALS CHEMEX  20  200  20  Ga  25  100  PCIGR  4  30  ALS CHEMEX  0  0 0  2  10  10  5  1 5  0 5  10  15 PCIGR  20  25  30  0  3  1  2 PCIGR  3  0  4  7  Lu  Mo ALS CHEMEX  ALS CHEMEX  10 PCIGR  15  20  4 3 2  Nd  80  Slope= 0.08.713 Int= 1.966 R2=.55  5  1  5  100  6  Slope= 0.9315 Int= 0.06171 R2=.84  2  ALS CHEMEX  0  0 0  Slope= 1.075 Int= -0.6845 R2=.98  60  40  Detection limit 20  1  0  0  0  1  2  3  0 0  1  2  PCIGR  3 4 PCIGR  5  6  7  0  20  40  60  80  PCGIR  Figure E.1: Comparison of trace element results from PCIGR (HR-ICP-MS) and ALS CHEMEX North Vancouver (ICP-MS). Methods Discussed in Chapter 3, All samples are included in Appendix C (PCIGR) and Appendix D (ALS CHEM). Detection Limit included where necessary.  198  80  70  300  Ni  La Slope= 1.030 Int= -0.3.643 R2=.98  200  ALS CHEMEX  40  Slope= 1.262 Int= -1.623 2 R =.97  50  ALS CHEMEX  ALS CHEMEX  60  Nb  60  Slope= 0.9790 Int= 3.391 R2=.99  100  40 30 20  20  10 0  0 0  10  20  30 40 PCIGR  50  60  0 0  70  100  200  300  0  10  20 PCIGR  PCIGR  30  40  50  4  30  Pb Slope= -5.156 Int= 23.16 R2=-.54  Slope= 0.9064 Int= 0.4639 R2=.98  3 ALS CHEMEX  ALS CHEMEX  60  ALS CHEMEX  20  Sn  Rb  80  40  2 Slope= 1.157 Int= 0.7.536  10  2  R =.8 1  20  Detection limit  Detection limit 0  0 0  10  20  30  0  20  PCIGR  80  0  100  3  400  Ta  Slope= 0.9558 Int= 1.245 R2=.99  2  ALS CHEMEX  200  2 PCIGR  3  4  Th  Slope= 1.552 Int= -0.2.123 2 R =.93  ALS CHEMEX  300  1  15  Sr ALS CHEMEX  40 60 PCIGR  Slope= 0.8666 Int= 0.2.331 R2=.76  10  1 5  100  Detection limit 0  0 0  100  200 PCIGR  300  0  400  2  0  5  10 PCIGR  500  2  V  U  400  Slope= 0.9329 Int= 0.05.320 r'=.89  Slope= 0.9245 Int= -1.699 r'=.98 ALS CHEMEX  ALS CHEMEX  1 PCIGR  1  Detection limit  300  200  100  0  0 0  1 PCIGR  2  0  100  200 PCIGR  300  400  500  Figure E.1 (continued): Comparison of trace element results from PCIGR (HR-ICP-MS) and ALS CHEMEX North Vancouver (ICP-MS). Methods Discussed in Chapter 3, All samples are included in Appendix C (PCIGR) and Appendix D (ALS CHEM). Detection Limit included where necessary.  199  15  200  8  Slope= 1.301 Int= 1.712 R2=.39  150 ALS CHEMEX  5 4 3  400  Int= 0.2881  Slope= 0.7.974 Int= 0.2.104  R2=.97  R2=.86 ALS CHEMEX  6  Zr  YSlope= 1.054  W  7  ALS CHEMEX  500  100  300  200  50  2  100  1  Detection limit 0 0  1  2  3 4 PCIGR  5  6  7  8  20  0  0  100 PCIGR  150  200  0  100  200 300 PCIGR  400  300  Zn  Yb Slope= 1.025 Int= 0.01.916 R2=.97  Slope= 0.09.213 Int= 5.524 R2=.91  200  ALS CHEMEX  15  ALS CHEMEX  50  10  100  5  0  0  0  5  10 PCIGR  15  20  0  100  200  300  PCIGR  Figure E.1 (continued): Comparison of trace element results from PCIGR (HR-ICP-MS) and ALS CHEMEX North Vancouver (ICP-MS). Methods Discussed in Chapter 3, All samples are included in Appendix C (PCIGR) and Appendix D (ALS CHEM). Detection Limit included where necessary.  200  500  

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