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Mid-crustal Cu-Au mineralisation during episodic pluton emplacement, hydrothermal fluid flow, and ductile… Hood, Shawn Bruce 2012

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Mid-crustal Cu-Au Mineralisation during Episodic Pluton Emplacement, Hydrothermal Fluid Flow, and Ductile Deformation at the Minto Deposit, YT, Canada  by Shawn Bruce Hood  B.Sc. (Hons.), Carleton University, 2008  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Geological Studies)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  July 2012  © Shawn Bruce Hood, 2012  Abstract The genesis of the Minto copper-gold deposit, YT, Canada, has been variously interpreted since its discovery although no existing model accounts for ductile deformation as a control on mineralization. Results from this study show that Minto ore is hosted within ductiley deformed granitoid host rocks emplaced as multiple intrusions into an actively deforming environment, with the variably sheared host rocks separated by incipiently deformed granodiorites essentially barren of mineralisation. Contacts between deformed/mineralized rock and incipiently deformed/barren rock range from abrupt to gradational, and are the product of pre-existing igneous contacts, variably partitioned deformation, or a combination of these. Deformation of granitoids is interpreted to have controlled fluid flow, with associated alteration promoting further deformation and fluid flow. Potassic alteration, in the form of biotite-magnetite, is the dominant alteration associated with mineralisation, and analysis of alteration using isocon diagrams indicates that K, Fe, Si, Cu, Au, and Ag have been added during alteration, although mass has been lost overall due to a relative reduction in Na and Ca. Host rock intrusion, mineralization, and deformation are interpreted via geochronology and crosscutting relationships as ongoing over at least 5 m.a., from about 202 Ma until about 197 Ma, based on U-Pb SHRIMP geochronology of zircons in granitoids and Re-Os ICP-MS geochronology of molybdenite. The trend of mineralisation is now coincident with the strike of foliation on short steep limbs and of axial planes of folded foliation. This geometry may not be representative of original processes, but of remobilization of ore during continued deformation. The above observations, coupled with data from existing studies, strongly suggest Minto is representative of deposit generation within an arc subduction environment at depths not typically considered for copper-gold deposit formation.  ii  Table of Contents Abstract .................................................................................................................................... ii Table of Contents ................................................................................................................... iii List of Tables .......................................................................................................................... vi List of Figures ........................................................................................................................ vii Acknowledgements ................................................................................................................. x Dedication ............................................................................................................................... xi Chapter 1: Introduction ........................................................................................................ 1 Chapter 2: Body of Thesis ..................................................................................................... 7 2.1  Geological Setting ..................................................................................................... 7  2.1.1  Regional Geology ................................................................................................. 7  2.1.2  Deposit Geology ................................................................................................. 10  2.2  Igneous Host Rocks ................................................................................................ 14  2.2.1  Intrusive Units ..................................................................................................... 16  2.2.1.1  K-Feldspar Granodiorite ............................................................................. 16  2.2.1.2  Coarse Grained Tonalite ............................................................................. 18  2.2.1.3  Dikes ........................................................................................................... 19  2.2.2  Internal Pluton Fabrics ........................................................................................ 21  2.2.3  Lithogeochemistry of KGd ................................................................................. 32  2.2.3.1 2.3  Results ......................................................................................................... 34  Mineralisation and Alteration ................................................................................. 38  2.3.1  Ore Assemblage .................................................................................................. 38  2.3.2  Alteration Assemblages ...................................................................................... 44  iii  2.3.3  Evaluating Mass Transfer ................................................................................... 47  2.3.3.1  Analytical Techniques ................................................................................ 47  2.3.3.2  Isocon Plots ................................................................................................. 51  2.4  Structural Geology .................................................................................................. 60  2.4.1  Solid State Microstructures ................................................................................. 61  2.4.1.1  Stage 1: Incipient Deformation ................................................................... 61  2.4.1.2  Stage 2: Weak Foliation .............................................................................. 65  2.4.1.3  Stage 3: Well Developed Penetrative Foliation (SP) ................................... 65  2.4.1.4  Stage 4: Mylonitic Foliation ....................................................................... 66  2.4.2  Gneissic Banding ................................................................................................ 67  2.4.3  Sulphide Deformation Fabrics ............................................................................ 70  2.4.4  Foliation and Shear Zone Geometry ................................................................... 73  2.4.5  Late Brittle Deformation ..................................................................................... 99  2.5  Geochronology...................................................................................................... 100  2.5.1  U-Pb SHRIMP Geochronology ........................................................................ 101  2.5.1.1  Samples ..................................................................................................... 101  2.5.1.2  Analyses .................................................................................................... 102  2.5.1.3  Results ....................................................................................................... 112  2.5.1.3.1 Suite One ............................................................................................. 112 2.5.1.3.2 Suite Two ............................................................................................ 112 2.5.2  Re-Os Molybdenite Geochronology ................................................................. 114  2.5.2.1  Samples ..................................................................................................... 114  2.5.2.2  Analyses .................................................................................................... 116  iv  2.5.2.3 2.6  Results ....................................................................................................... 117  Summary ............................................................................................................... 118  2.6.1  Relationship between Igneous Activity, Alteration, and Deformation ............. 118  2.6.2  Geochronology.................................................................................................. 124  2.7  Discussion ............................................................................................................. 127  2.7.1  Petrogenesis and Emplacement Depth .............................................................. 127  2.7.2  Synopsis of the Crustal Environment During Emplacement of the Minto Pluton 130  2.7.3  Pluton Emplacement and Ductile Deformation ................................................ 134  2.7.4  Deformation, Permeability, and Hydrothermal Fluid Flow .............................. 139  2.7.5  Hydrothermal Alteration ................................................................................... 142  2.7.6  Comparisons with Other Cu-Au-Magmatic Related Ore Systems ................... 146  Chapter 3: Conclusion ....................................................................................................... 153 References ............................................................................................................................ 155 Appendices ........................................................................................................................... 169 Appendix A Field Measurements ..................................................................................... 170 Appendix B Pit Maps ........................................................................................................ 186 Appendix C Whole-Rock Geochemical Sample Locations .............................................. 191 Appendix D Whole-Rock Lithogeochemical Data ........................................................... 193 Appendix E Isocon Calculations ....................................................................................... 199 Appendix F Graphical Logs .............................................................................................. 200 Appendix G U-Pb Geochronology.................................................................................... 215 Appendix H Molybdenite Study ....................................................................................... 217  v  List of Tables Table 1: Comparison of lithologies recognized by previous workers at Minto ...................... 15 Table 2: Geochemical sample information. ............................................................................ 33 Table 3: Lithogeochemical sample information from samples collected during 2009 field season.. .................................................................................................................................... 50 Table 4: Results of U-Pb SHRIMP analyses of KGd zircons and age calculations.. ........... 104 Table 5: Sample data from molybdenite ............................................................................... 117 Table 6: Temperature estimates based on observed microtextures ...................................... 137  vi  List of Figures Figure 1: Cross section through idealized subduction zone and continental arc ...................... 2 Figure 2: Regional geological setting of the Minto pluton and deposit.. .................................. 8 Figure 3: Interpretative map of major lithologies and important structures in the Minto deposit, excluding quaternary sediments. ............................................................................... 11 Figure 4: Two main granitoids comprising the Minto pluton: K-feldspar megacrystic granodiorite (KGd) and coarse grained tonalite (Tlt).. ........................................................... 17 Figure 5: Photographs of pegmatite dikelets (Pglt) showing the variety of crosscutting relationships with KGd and foliation. ..................................................................................... 20 Figure 6: Mafic magmatic enclaves (MMEs) within KGd ..................................................... 23 Figure 7: Photographs of mafic enrichments defining igneous layering. ............................... 25 Figure 8: Crosscutting relationships involving distinct intrusions of KGd indicating multiple stages of intrusion.. ................................................................................................................. 28 Figure 9: Photos showing crosscutting relationships involving intrusions of Tlt which indicate multiple stages of intrusion.. ..................................................................................... 30 Figure 10: Whole-rock lithogeochemical granite type discrimination diagram based on total alkalis versus total silica (TAS). ............................................................................................. 35 Figure 11: Whole rock lithogeochemical characterization of KGd using trace elements. ..... 36 Figure 12: Photographs and photomicrographs of hypogene mineral assemblages related to sulphide mineralization. .......................................................................................................... 40 Figure 13: Plots of metal tenor using company geochemical data (Captone Resources dataset, unpublished)............................................................................................................................ 43 Figure 14: Photomicrographs showing selected alteration assemblages ................................ 45  vii  Figure 16: Spider diagrams comparing samples used in isocon study, samples collected regionally, and samples analysed during previous study ........................................................ 54 Figure 17: Plots to assess chemical immobility within altered/deformed samples of KGd.... 55 Figure 18: Isocon diagram illustrating relative enrichment and depletion of major element oxide (wt %) and trace element (ppm) concentrations in the Minto Granodiorite.. ............... 57 Figure 19: Photographs showing hand samples of deformed KGd ........................................ 62 Figure 20: Photographs showing compositional banding in KGd .......................................... 68 Figure 21: Photomicrograph showing microtextures of typical Cu-sulphide deformation at Minto.. ..................................................................................................................................... 71 Figure 22: Photomicrograph showing macroscopic deformation of Cu-sulphides at Minto. . 72 Figure 23: Stereonets depicting SP foliations measured at Minto........................................... 74 Figure 24: Photomicrographs showing examples of structural contacts in KGd.................... 75 Figure 25: Photo showing SP fabric developed in a stoped enclave of deformed and magnetite altered KGd. ............................................................................................................................ 78 Figure 26: Downhole variation of SP in unoriented vertical drillholes ................................... 79 Figure 27: Schematic diagrams illustrating possible interpretations of geometry from S P foliation observed in unoriented drillcore ............................................................................... 82 Figure 28: Orthophoto of the Minto mine showing the locations of logged diamond drill holes, figures with pit photographs and structural data, and cross sections. .......................... 83 Figure 29: Examples of shear zones in the Minto open pit..................................................... 85 Figure 30: Stereonets of SP measured from regions across the Minto deposit. ...................... 88 Figure 31: Variation of SP folding observed within shear zones in the Minto open pit. ........ 91  viii  Figure 32: Graphical log of diamond drill hole 06SWC078 showing a correlation between potassic alteration, sulphide type, and ore grade. ................................................................... 93 Figure 33: Map of the Minto open pit summarising SP foliation geometry. ........................... 95 Figure 34: Steep foliation and Cu-grade thickness from the Minto deposit.. ......................... 97 Figure 35: Concordia diagrams for U-Pb SHRIMP analysis of KGd zircons. ..................... 110 Figure 36: Photomicrographs showing textures in molybdenite samples suggestive of relative timing. ................................................................................................................................... 115 Figure 37: Cross sections from the Minto deposit showing the continuity of deformation zones, mineralization, and potassic alteration....................................................................... 119 Figure 38: Annotated photograph of KGd samples showing summary of U-Pb SHRIMP zircon ages. ........................................................................................................................... 125 Figure 39: Schematic of Minto deposit paragenesis. ............................................................ 132 Figure 40: Simplified schematic diagram of magma generation and emplacement within a subduction arc environment. ................................................................................................. 151  ix  Acknowledgements I offer my enduring gratitude to the faculty, staff and my fellow students in the Department of Earth and Ocean Sciences, who made my time at the UBC so fulfilling and who shared my enthusiasm for geology. I owe particular thanks to my supervisor Dr. Kenneth Hickey, with whom I enjoyed working immensely. I thank my external supervisor Dr. Maurice Colpron of the Yukon Geological Survey for being a grounding influence during my studies and for enlarging my vision Yukon geological history and tectonics. Gratitude also to Brad Mercer, vice-president of exploration from the Capstone Mining Corp., for organizing the project and for giving practical guidance in the field. Much appreciation to Dr. Nancy Joyce and Dr. Nicole Rayner for their assistance producing U-Pb SHRIMP ages and to Dr. Dave Selby for his role in producing Re-Os ages. Many thanks to Dr. Jim Mortensen and Dr. James Scoates who sat on my defence committee and posed many penetrating and thought provoking questions. I am grateful to the Capstone Mining Corp. and the Yukon Geological Survey for funding this research project in its entirety. Dani Aldrich, Taras Nahnybida, and Vivienne Mclennan from Capstone were very helpful contributers as field partners, data providers, and proof readers. To Hickeylab and friends: I could not imagine my M.Sc. experience without any of you. Thank you for everything. Special thanks to my lovely and patient fiancé Ayesha, who is the transporting ligand to my aqueous metal ion. Thanks for helping me through, love.  x  Dedication Dedicated to my family, especially Grandma and Grandpa Hood, and Oma and Gramps Koens, for their love and encouragement over the years.  xi  Chapter 1: Introduction The majority of Earth’s economic copper deposits are associated with felsic magmatism in arc-environments. In particular, the porphyry-Cu class of deposits hosts approximately 75% of the world’s copper supply (Sillitoe, 2010). Mineralisation in porphyry deposits is hydrothermal in origin and is spatially and temporally associated with porphyritic granitoid stocks and dikes of calc-alkaline to alkaline composition, in many cases being hosted by them (Cloos, 2001; Richards, 2005). Such granitoid intrusions and coincident mineralisation are typically emplaced at 1-4 km depth, but may occur as deep as 9 km (Singer et al., 2008). In contrast, the magma forming these intrusions and the metalliferous hydrothermal fluids responsible for mineralisation are typically sourced from large parental magma chambers 5 to 15 km below the granitoid stocks (Figure 1) (Cloos, 2001; Richards, 2005; Singer et al., 2008). The fluid is exsolved from the cooling and fractionating parental magma during magma convection as well as during magma crystallization (Shinohara and Hedenquist, 1997). The granitoid stocks and dikes of porphyry systems, while not necessarily major contributors of metalliferous magmatic fluids, act to channel these fluids upwards towards the site of their deposition (Shinohara et al., 1995; Cloos, 2001; Richards, 2005). Historically, the majority of research involving Cu metallogenesis has been focussed on porphyry-Cu systems in the upper 9 km of the crust, with a paucity of data and research involving deeper magmatic environments. This higher crustal focus is linked to the limited exposure of deep systems that can be clearly linked to porphyry deposits. Nevertheless, workers interpreting a deeper fluid source for porphyry deposits have long  1  Figure 1: Cross section through a subduction zone and continental arc (modified from Richards, 2003). Dehydration of the subducting oceanic crust leads to hydration of the overlying mantle. Partial melting occurs as hydrated material is convected to hotter regions of the asthenospheric mantle wedge. Evolved, more buoyant magmas rise away from this zone of melting, assimilation, storage, and homogenisation (i.e., MASH zone, Hildreth and Moorbath, 1988) through the crust dominantly via fractures/dikes. Porphyry fluids are thought to originate from mid to upper crustal batholiths and be emplaced at shallower levels via overlying stocks/dikes (Cloos, 2001). Diagram is not to scale.  2  hypothesized that the large parental “roots” to porphyry systems are an underexplored prospect for magmatic related Cu-Au mineralisation (Sillitoe, 1973; Seedorff et al., 2008). This raises the question of how any such mineralisation might be manifest in large mid to upper crustal magma chambers and how might it relate to their initiation, growth and crystallization? Porphyry deposits have long been associated with subduction zones, and workers have successively refined the tectono-magmatic controls on mineralisation using the context of convergent arc environments (Sillitoe, 1973; Richards, 2003; Sillitoe and Hedenquist, 2003). According to this model, fertile calc-alkaline magmas are generated in the MASH zone, a zone of melting, assimilation, storage, and homogenisation (Hildreth and Moorbath, 1988). The initial ascent of hydrous magmas generated in deep crustal MASH zones (DePaolo and Wasserburg, 1977; Hawkesworth, 1982; Brown et al., 1984; Hildreth and Moorbath, 1988) is likely controlled by grain scale percolative flow of melt during ductile deformation (Collins and Sawyer, 1996; Brown and Solar, 1999; Schilling and Partzsch, 2001). Melt progressively gathers to feed larger conduits, dikes or diapirs that go on to form larger magma chambers at shallower depths (Collins and Sawyer, 1996; Brown and Solar, 1999). The initiation and growth of large magma chambers commonly involves the emplacement of multiple batches of magma via some combination of dyking and diapirism (Weinberg and Podladchikov, 1994; Petford, 1996; Brown and Solar, 1998; Petford et al., 2000a; Pignotta et al., 2010;). At higher crustal levels magma chambers tend to grow by vertical inflation and roof uplift through the intrusion of multiple shallow dipping sheet-like intrusions along rheological heterogeneities, and/or by magmatic stoping of country rocks (Brown and Solar, 1998; Cruden, 1998; Morgan et al., 1998; Becker et al., 2000; Zak and Paterson, 2006; Miller  3  et al., 2009; Clemens and Benn, 2010). Although the growth of such magma chambers commonly involves significant internal flow and deformation of melt, resulting in the formation of mafic schlieren and magmatic foliations and lineations (e.g., Paterson, 2009), there is little syn-intrusive development of pervasive solid-state foliations within the country rock or earlier solidified intrusive phases. However, with increasing crustal depth and higher country rock temperatures the emplacement of magma and the growth of large magma chambers involves a greater degree of ductile deformation of wall rocks and earlier emplaced magma pulses. Vertical growth of magma chambers is dominated by floor depression via solid state ductile return flow of the country rock rather than roof uplift (Cruden, 1998; Wiebe and Collins, 1998; Cruden and McCaffrey, 2001; Žák and Paterson, 2005). Lateral growth of magma chambers can occur via radial flattening and vertical elongation of the hot country rocks in the thermal aureole surrounding the magma chamber, and/or of earlier magma pulses within the magma chamber itself (Siegesmund and Becker, 2000; Johnson et al., 2003). Such flattening is driven by magma pressure and is accomplished by thermally activated solid-state intracrystalline deformation (of country rock and sub-solidus intrusive rocks) and/or magmatic flow (of earlier intrusive phases still in a supra-solidus state). Regional deformation of country rocks controlled by forces external to the emplacing magma can also play a significant role in the growth of mid-crustal magma chambers. Several studies have documented the preference for magma to be emplaced in dilatant sites within and adjacent to large crustal shear zones in convergent tectonic settings (Vigneresse, 1995; Brown and Solar, 1998; Koukouvelas et al., 2002; Weinberg et al., 2004; Weinberg et al., 2009). Owing to changing patterns of regional deformation partitioning, magmas intruded into such tectonically active regions are commonly overprinted by deformation prior to and  4  after they have cooled below the solidus resulting in solid state and /or magmatic foliations in plutons that are parallel to regional fabrics (Brown and Solar, 1998; Weinberg et al., 2004; Weinberg et al., 2009; Pignotta et al., 2010). Given their mid to upper crustal depth and convergent arc setting, the growth initiation and growth of the large parental magma chambers that feed upper crustal porphyry-Cu deposits should, in many cases, have involved synchronous ductile deformation of country rock and/or earlier emplaced magma pulses. It seems likely that such deformation might also influence the evolution, and passage of magmatic derived metalliferous fluids within, and out from, mid-crustal magma chambers that feed porphyry-Cu deposits. Deformation should have a first order influence on permeability and on the extent of fluid rock interaction (Dipple and Ferry, 1992; Cox, 2005) and this should directly affect the spatial distribution of alteration and mineralisation associated with the hydrothermal fluid exsolved from a crystallizing melt. The Minto pluton in the Yukon Territory, Canada, is a ductiley deformed calc-alkaline granitic intrusion hosting a Cu-Au deposit that may represent an example of a mid-crustal metalliferous magma body like that thought to underlie and feed porphyry-Cu systems. Although previous studies have suggested the deposit has many characteristics of a porphyry system (Tafti, 2005), thermobarometry places the intrusion of Minto host rocks at 15-25 km (Tafti, 2005), far deeper than the deepest published porphyry systems (Singer et al., 1989) but within depths proposed for magma chambers thought to feed porphyry systems (Cloos, 2001; Richards, 2003; Brown, 2007). To better understand the interaction of deformation and magmatic related Cu-Au mineralisation at sub-porphyry depths, this study examines the geometric patterns and kinematic history of ductile deformation in the Minto pluton and assesses its genetic relationship to mineralisation. The specific goals of this study are to  5  assess the relationship between felsic calc-alkaline intrusions, contemporaneous ductile deformation, and hydrothermal mineralisation to understand whether the Minto deposit is a product of a magmatic system analogous to those inferred to feed porphyry systems. Key observations and interpretations made in this study include: (i) calc-alkalic arc granitoids have been emplaced in the ductile regime as episodic intrusions, (ii) the range in timing for hypogene sulphide mineralisation is contemporaneous with episodic granitoid intrusion, (iii) a positive feedback relationship between ductile deformation and hydrothermal alteration is likely responsible for the observed geometry at Minto, and finally (iv) the Minto deposit represents an intrusion related hydrothermal Cu-Au-Ag deposit located within a convergent arc framework where magma emplacement and mineralisation occurred in the ductile regime at depths below deep porphyry-Cu deposits. As such, Minto represents mineralisation in a parental magma chamber, such as those described to feed porphyry stocks and dikes, and a new potential for exploration arc settings.  6  Chapter 2: Body of Thesis 2.1 2.1.1  Geological Setting Regional Geology  The Minto pluton is part of the Aishihik plutonic suite (Figure 2) which also includes the Aishihik batholith to the south, and the Walhalla Creek pluton, McGregor Creek pluton, Tatchun batholith, and Granite Mountain batholith. The Aishihik suite forms a belt of Early Jurassic calc-alkaline intrusions extending from west of Whitehorse to east-central Alaska that define a continental arc within the Yukon-Tanana terrane (Johnston et al., 1996a; Mortensen et al., 1999). The Minto pluton (Figure 2) intrudes the Upper Triassic augitephyric basalts of Stikinia (the Lewes River Group) to the east and north, and Late DevonianEarly Mississippian meta-plutonic rocks of Yukon-Tanana terrane (Simpson Range plutonic suite) to the west (Tempelman-Kluit, 1984; Gordey and Makepeace, 1999; Colpron, 2006). The northern end of the Minto pluton is covered by Pliocene and younger basalt flows of the Selkirk Group. The eastern contact of the Minto pluton with Triassic rocks is locally faulted. Geological relationships at the southern end of the Minto pluton are obscured by the Cretaceous Carmacks Group which unconformably overlies the Early Jurassic Aishihik plutonic suite, represented in the southeast of the Minto deposit by a clast-supported cobble to boulder conglomerate comprised of Minto lithologies (Figure 3). Minto may link to the south, under the Carmacks Group, with the Granite Mountain batholith (Tafti, 2005).  7  Figure 2: Regional geological setting of the Minto pluton and deposit. The Minto pluton is part of the Aishihik plutonic suite, a northwest trending belt of Jurassic-Cretaceous aged felsic intrusions in southwest Yukon extending into Alaska (marked in black on inset map) interpreted as the result of arc subduction. Fault contacts to the east and south obscure the contact relationship between the pluton and country rocks of the Yukon-Tanana terrane. Younger quaternary sediments and Upper Cretaceous Carmacks Group unconformably overlie older rocks, further obscuring geologic relationships. Deposit margins are inferred from Capstone Resources’ exploration drilling. Figure modified from Colpron, 2006.  8  Existing geochronologic U-Pb zircon measurements using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) by Tafti (unpublished M.Sc. thesis data) suggest the Minto pluton was emplaced at approximately between 197 Ma and 201 Ma. Hornblende geobarometry and geothermometry by Tafti (unpublished M.Sc. thesis data) suggests emplacement of Minto granodiorite at depths greater than 15 km. Detrital zircons taken from a cobble conglomerate composed of Minto deposit lithologies indicate a maximum age of 77 Ma for this overlying sediment, indicating that the deposit was subaerial by the Late Cretaceous. Within the area encompassing the Minto deposit, the otherwise massive Minto pluton is transected by numerous ductile shear zones with well-developed foliation and a generally shallow orientation. These zones are millimetres to hundreds of metres wide and up to ~1 km in lateral extent. The zones of foliated rock are spatially associated with Cu-Au mineralisation manifested as disseminated chalcopyrite and/or bornite with locally occurring stringers or massive sulphide. Measured and indicated resources as of 2010 were 29.9 Mt @ 1.2% Cu, with 365 Kt Cu, 12t Au, and 122t Ag (Annual Technical Report, 2009), with the tenor of hypogene gold and silver mineralisation coincident with copper assay values. Scanning Electron Microprobe (SEM) scans indicate that gold and silver are contained within bornite and chalcopyrite (pers. Comm., Capstone mine staff, 2010). Gold is typically microscopic although native gold has been observed in fractures and epidote veins (pers. comm., Capstone mine staff, 2010). Brittle faulting is common at the deposit and dissects the foliated deformation zones. The largest fault on the property is the DEF fault (Figure 3), an approximately east-west trending fault dipping about 60º to the north. This fault zone is defined by well-developed breccia,  9  gouge, and low temperature clay alteration minerals several metres in thickness. Although slip along the fault is unknown, abundant cataclasite and offset between mineralized zones on either side of the fault suggest displacement on a scale of hundreds of metres. The main ore bodies within the Minto pit are truncated by the DEF fault, although smaller zones of mineralization are present within the hangingwall. 2.1.2  Deposit Geology  Interpretations of ore genesis at the Minto deposit have been widely debated since its discovery in 1973. Gale (1976) posited direct precipitation of Cu-Fe sulphides from a melt. Pearson (1977) was first to recognize the association between deformation and ore grade, but interpreted the system as a pre-existing sedimentary hosted copper deposit or hydrothermal deposit that had been metamorphosed and intruded by later granitoids. Mortensen et al. (1999) believed that the Minto deposit is a porphyry-style deposit pre-dating deformation and occurring before the intrusion of granitoids interpreted as part of the Granite Mountain batholith. Gordey and Makepeace (2001) proposed that the deformed host rocks containing Minto mineralisation were roof pendants within the Granite Mountain Batholith. This concept and the early work by Pearson (1977) was extended by Tafti (2005) using Thermal Ionization Mass Spectrometry (TIMS) dating of zircons, whole-rock geochemistry, and sulphur/lead isotope characterization.  10  Figure 3: Interpretative map of major lithologies and important structures in the Minto deposit, excluding quaternary sediments. The distribution of lithologies and their contacts is interpreted from surface mapping undertaken in 2008 and bedrock intersections from company drilling. K-feldspar  11  granodiorite and equigranular tonalite are part of the Minto pluton. Minto Conglomerate is interpreted as basal Carmacks Group (shown in Figure 2) (Tempelman-Kluit, 1974, Tempelman-Kluit, 1984). Important structures include zones where foliation (SP) is steep (>= 60º) and major faults. Steep foliation measurements were recorded from outcrops or from oriented drill holes. The trend of steep foliation, NNW-SSE, is coincident with the main mineralization trend of the Minto deposit. Shallow foliations are omitted on this map for the sake of clarity. Fault locations are inferred from outcrop exposure, drill intersections, and airborne magnetic data.  12  Using these results, Tafti (2005) interpreted Minto as a partially formed porphyry deposit wherein hydrothermal activity stalled and the deposit was buried, metamorphosed, and partially digested within a granitic diapir. This model contrasts with slightly earlier work by McCausland et al. (2002) who interpreted ages, intrusion depths, and geological relations observed in the Granite Mountain Batholith as evidence that it was emplaced into deformed gneiss as the youngest magmatic product in an active shear zone, and that magmatic fabric along the west margin of the batholith may indicate the nearby presence of the shear zone’s northwest trending wall within the Early Jurassic continental magmatic arc.  13  2.2  Igneous Host Rocks  The Minto deposit is hosted within the Minto pluton, a body mainly comprised of calcalkalic K-feldspar megacrystic granodiorite (Bostock, 1936; Pearson, 1977). Because of extensive deformation and alteration at the Minto deposit, previous workers describe a range of pseudolithologies representing a mix of protolith mineralogy, alteration mineralogy and deformation textures (Table 1). In this study, igneous rock types are defined using protolith mineralogy and chemistry. The effects of overprinting alteration and ductile deformation are considered separately.  14  Table 1: Comparison of lithologies recognized by previous workers at Minto  Hood (2010)  Bostock (1936)  Pearson (1976)  Tafti (2005)  K-feldspar Granodiorite (KGd)  Granodiorite  Klotassin Granodiorite (granodiorite, diorite, qzmonzodiorite)  Granodiorite (granodiorite, syenite, tonalite)  Granite/diorite gneiss  Quartzofeldspathic gneiss (Kfs- or Qz-rich) Biotite-rich gneiss  Quartzofedspathic gneiss  Siliceous ore  Siliceous ore  Foliated granodiorite  Biotite-rich gneiss  Foliated Biotite Granodiorite Biotite--quartz-feldspar gneiss Blotchy-textured hornblende biotite granodiorite  Hornblende-biotite diorite (KGd sub-unit)  fine-grained foliated hornblende diorite  Coarse Grained Tonalite (Et)  Foliated hornblende diorite  Granite pegmatite  Granite pegmatite  Diorite (quartz diorite, quartz monzodiorite, and diorite)  Granitic Pegmatite  K-feldspar-quartz pegmatite Aplite  Aplite  Not observed  foliated to non-foliated biotite microgranite  Not observed  Alaskite  Not observed  Augite andesite  Foliated Grey biotite Aplite  15  2.2.1 2.2.1.1  Intrusive Units K-Feldspar Granodiorite  K-feldspar megacrystic granodiorite (KGd, Figure 3 and Figure 4A) is the dominant rock type within the Minto Pluton and within the study area. This variety of granitoid actually composes a continuum of granitoid variants, grading from crowded K-feldspar megacrystic syenite to equigranular tonalite or quartz diorite (Pearson, 1977; Tempelman-Kluit, 1984; Tafti, 2005), based on classification using modal abundance of total quartz-alkali feldsparplagioclase (from Streckeisen, 1974). In general, KGd contains approximately 30% to 50% plagioclase, 10% to 50% K-feldspar, 20% to 25% quartz, and total biotite ± hornblende 10% to 15%. Accessory minerals include magnetite, epidote, titanite, apatite, and zircon. These minerals display sharp euhedral crystal faces in thin section. K-feldspar occurs most commonly as megacrysts 1 to 3 cm long with internal oscillatory zoning. Inclusions of biotite, plagioclase, hornblende, epidote, and zircon are common along growth zones. KGd tending to tonalite or diorite compositions typically contains anhedral K-feldspar rather than K-feldspar megacrysts. Plagioclase occurs up to 1 cm in length and occurs as euhedral to anhedral equigranular crystals evenly distributed throughout the rock mass. Igneous growth textures such as stepped twins and oscillatory zoning are common in plagioclase. Quartz forms anhedral masses interstitial to feldspars, but it locally forms glomeroporphyritic masses (henceforth referred to as “quartz eyes”) up to 1 cm in diameter. Randomly oriented biotite crystals up to 5 mm and/or euhedral hornblende up to 7 mm compose up to ~15% of KGd.  16  Figure 4: Two main granitoids comprise the Minto pluton: K-feldspar megacrystic granodiorite (KGd) and coarse grained tonalite (Tlt). Sample locations given in Appendix C A. KGd is the most common variant and is typically medium-grained with centimetre-scale K-feldspar megacrysts. The modal mineral composition ranges from syenite to quartz monzodiorite to diorite to tonalite (classification after Streckeisen, 1974). Kfs = K-feldspar. Sample S09-13-03A. B. KGd contains abundant magmatic epidote (Epi) with characteristic euhedral crystallinity, sharp grain boundaries with plagioclase and biotite, growth zoning, and allanite (al) cores. Bt = biotite. Sample SBH-C009. C. Coarse grained tonalite (Tlt) contains plagioclase (Pl) and euhedral hornblende (Hbl) that are typically approximately 5mm, in contrast with the more medium grained KGd. K–feldspar megacrysts are not present within this unit. Tlt was not observed to vary appreciably in bulk mineralogy. Sample H424-251.6.  17  Mafic component varies from 100% biotite to 100% hornblende but in most areas these minerals are both present. Magmatic epidote (Figure 4B) is a potentially important indicator of crystallization depth and occurs as both inclusions in feldspar and as individual grains. Secondary epidote is common at Minto, and magmatic epidote was identified using the following criteria (as described by Zen and Hammarstrom, 1984; Liu et al., 1999; Schmidt and Poli, 2004b): sharp euhedral boundaries with mafic phases, growth zoning, and allanite cores. Inclusions of magmatic epidote within K-feldspar and plagioclase are < 0.15 mm, highly birefringent, zoned, and euhedral to subhedral. Individual magmatic epidote grains interstitial to other minerals are 0.5 to 2 mm, euhedral to subhedral, zoned, and contain brown-green allanite cores visible in thin section (B). 2.2.1.2  Coarse Grained Tonalite  Intrusions of coarse-grained tonalite (Figure 4C) at the Minto deposit are typically less than a metre in thickness and crosscut KGd. Modal composition is approximately 75% plagioclase, 20% quartz, <10% biotite +/- hornblende. Plagioclase and hornblende are up to 6 mm, notably larger than their counterparts in KGd. Plagioclase is euhedral to subhedral with growth zoning or lamellae. Quartz is interstitial to feldspar. Mafic minerals include biotite +/hornblende and epidote. Zircons are present as an accessory and display complex overgrowths. Enclaves of this unit were observed most frequently within strongly deformed and altered zones of KGd and are themselves weakly boudinaged and folded, although growth textures in igneous phenocrysts, such as oscillatory zoning and growth lamellae, are largely preserved.  18  2.2.1.3  Dikes  Five types of dikes were observed crosscutting the granitoids of the Minto Pluton, from youngest to oldest: (i) hornblende diorite dikes, (ii) Andesite dikes, (iii) aplite dikes, (iv) granitoid pegmatites, and (v) quartzofeldspathic lets (Figure 5). Hornblende diorite dikes crosscut all units and do not exhibit evidence of alteration or ductile deformation, even at microscale. This is in contrast with all other observed dike varieties. Andesite and aplite dikes are observed as individual intrusions within massive and deformed rocks, intruding along or within pegmatites, or as angular breccia clasts within deformation zones. Plagioclase is typically moderately weathered or altered to sericite. Aplite crosscutting mineralized rock locally carries sulphides, possibly mobilized from mineralized hostrock.  19  Figure 5:Photographs of pegmatite dikelets (Pglt) showing the variety of crosscutting relationships with KGd and foliation. These relationships suggest several episodes of intrusion and varying timing relative to regional deformation. A. Pegmatite dikelets crosscutting KGd indicating intrusion after KGd. B. Deformed pegmatite dikelet intruded and deformed along biotite foliation in deformed and altered KGd. This relationship indicates intrusion before cessation of deformation accommodated along foliation. C. Undeformed planar pegmatite dikelet intruded along biotite foliation in deformed and altered KGd. Relationship suggests intrusion after the cessation of deformation accommodated along foliation. D. Undeformed pegmatite dikelet crosscutting biotite foliation. This relationship indicates intrusion after the cessation of deformation accommodated along biotite foliation.  20  Large granitoid pegmatite dikes up to 1 m in thickness are present throughout the Minto deposit and have been dated using U-Pb isotope dilution–thermal ionisation mass spectrometry (ID-TIMS) techniques on zircons at 195.5 (+/- 0.7) Ma (Tafti, 2005). Contacts with wallrock are sharp, with no observable thermal effects, such as grain size reduction along pegmatite margins or deformation in wallrock. Plagioclase, K-feldspar, quartz, and biotite are typically coarse- to very coarse-grained. Inclusions of sulphides are locally present in intervals that crosscut mineralized hostrock. Orientations of dikes vary and crosscutting relationships between pegmatite dikes suggests multiple intrusion events. Finally, quartzofeldspathic dikelets exhibit pegmatitic K-feldspar, plagioclase, and quartz. These pegmatite dikelets are up to several centimetres in thickness with sharp margins. Quartzofeldspathic dikelets crosscut both massive (Figure 5A) and deformed rocks (Figure 5B, C, and D). In deformation zones, these dikelets may intrude along foliation (Figure 5B and C) or crosscut it (Figure 5C). The range of textures and crosscutting relationships suggests that quartzofeldspathic dikelets were emplaced during several episodes relative to deformation. 2.2.2  Internal Pluton Fabrics  Foliations in granitoids can form by magmatic flow, ‘submagmatic flow’, high-temperature solid-state deformation and moderate- to low-temperature solid-state deformation (Paterson et al., 1989). Magmatic fabrics within the Minto pluton occur within, and between, individual intrusions of KGd and Tlt and are separate from the solid-state deformation textures, i.e., foliation and gneissic banding, discussed below. Fabrics include mafic magmatic enclaves, mafic mineral accumulations or schlieren, igneous emplacement contacts, and magmatic mineral lineation.  21  Mafic magmatic enclaves (MMEs, after Barbarin, 1999) are observed regionally in KGd (Figure 6) as centimetre to metre scale rock masses composed of biotite, magnetite, titanite and epidote. These xenoliths are locally impinged by euhedral K-feldspar (Figure 6A), suggesting they predate feldspar growth. Mafic-rich zones were observed with a variety of habits: sharply bounded enclaves (Figure 6A), enclaves with irregular boundaries with KGd (Figure 6B), and as mafic enclaves with gradational boundaries with KGd (Figure 7A). Mafic magmatic enclaves are common in calc-alkaline granitoids (Didier, 1991) and are abundant in most of the Cordilleran granitoids (e.g., Pitcher, 1982; Barbarin, 1999). Mafic enclaves in granitoids have been postulated as related to restite material from resorbed fragments of country rock (Chappell et al., 1987), basaltic magma injections into granitoid magma chambers (Huppert and Sparks, 1988; Wiebe and Collins, 1998; Wiebe et al., 2002), mixing/mingling between mafic and felsic magma within magma chambers (Furman and Spera, 1985; Vernon et al., 1988), and as the product of late mineral coarsening during crystallization of granitoid magma chambers (Boudreau, 2011).  22  Figure 6: Mafic magmatic enclaves (MMEs) within KGd may indicate pre-solidus intrusion of mafic magma into the KGd magma chamber or mineral differentiation within the Minto pluton. MMEs were observed with both regular and irregular boundaries. A. MMEs, tens of centimetres in scale, locally appear to be impinged by K-feldspar megacrysts, possibly indicating the late growth of K-feldspar with enough local liquid magma to settle into xenoliths (Clemens and Wall, 1981; Vernon and Paterson, 2008). B. MME sharing irregular boundary with KGd, suggesting KGd had not completely solidified at the time enclaves were emplaced.  23  Mafic accumulations are especially common in the margins of intrusions, adjacent to contacts with other granitoids or with country rocks (Barbarin, 1999). Mafic aggregates can form schlieren layering (Barbarin, 1999), and contacts between mafic aggregates and granitoids can be either sharp or diffuse (Barbarin, 1999), meaning that gradational contact shown in Figure 7A, defined by an aggregation of minerals also observed within enclaves, may represent schlieren layering within KGd. Schlieren layering was also observed in Tlt cropping out in road cuts east of the main deposit (Figure 7B). These rhythmic successions of layers are composed of millimetre thick layers of moderately aligned biotite, hornblende, epidote, magnetite, and titanite separated by felsic layers 1 – 50 cm thick of medium- to coarse-grained quartz and plagioclase with lesser amounts of biotite, hornblende, epidote, magnetite, and titanite (Figure 7C). This zone of schlieren layering is tens of metres wide and appears to have been intruded by a layer parallel tonalite sill (Figure 7A and B). Only weak ductile deformation microfabrics are present in these layers, supporting interpretation as an igneous foliation. These schlieren have a subvertical eastward dip in outcrop. Regional paleomagnetic studies by McCausland et al. (2002) suggest that plutonic rocks in the Aishihik plutonic suite have not been reoriented from the horizontal by more than 3º since formation, therefore the steep orientation of schlieren could be due to processes within the forming pluton, e.g., due to sinking wall rock rafts (after Wiebe et al., 2007). However, varying dip of the Minto conglomerate observed by Tafti (2005) and Mortensen (pers. comm.) may be evidence of greater reorientation, e.g., due to fault block rotation.  24  25  Figure 7: Photographs of mafic enrichments defining igneous layering. A. Gradational contact into mafic enrichment with sharply bounded basal contact with KGd, indicating mineral differentiation within the forming Minto pluton through settling of mafic minerals as a cumulate or through “filter pressing”. B. Mafic layering in tonalite interpreted as schlieren (after Didier and Barbarin, 1991) occurring as a zone of layered Tlt in outcrop at the scale of tens of metres. C. Enlarged view of alternating mafic- and felsicrich layering. Mafic phases include biotite, hornblende, epidote, magnetite, and titanite. Felsic layers are interpreted as Tlt. D. Schematic representation of outcrop illustrating the layer-parallel lobe of Tlt, interpreted as a sill. Such a cross cutting relationship indicates igneous emplacement occurring after host rock crystallisation to the degree that schlieren are able to form.  26  Igneous contacts between intrusions of granitoid were identified using the criteria of Streckeisen (1974), i.e., common crystal alignment along contacts, phaneritic crystal texture in adjacent rocks, and igneous mineral textures (e.g., straight intermineral crystal faces or growth zoning) without strong deformation microtexture overprints. Contacts between granitoids at Minto are sometimes difficult to distinguish because of gradation between variants within individual masses, or because granitoids in igneous bodies may have similar grain size and mineralogy. Crowded K-feldspar porphyry KGd was observed across the Minto pluton and is useful for delineating igneous contacts, e.g., due to the abrupt termination of the porphyritic rock with other granitoids and due to the tendency for magmatic flow alignment of megacrysts along contacts (Figure 8A). Igneous contacts between pulses of KGd were observed between masses of KGd at the scale of metres (Figure 8A) and on the order of centimetres involving stoped enclaves (Figure 8B). Igneous KGd contacts are also exemplified by the crosscutting of pre-existing deformation fabrics such as biotite foliation (Figure 8C). Only single contacts were observed, meaning the thickness of individual pulses could not be determined. Similar igneous contacts were observed involving Tlt (Figure 9). Igneous Tlt contacts are recognized due to the more coarse-grained nature of plagioclase, bioite, and hornblende. Four igneous contacts between Tlt and KGd were observed in unoriented vertical drillholes and were shallowly dipping, i.e., less than 40 degrees.  27  Figure 8: Crosscutting relationships involving distinct intrusions of KGd indicating multiple stages of intrusion. A. Planar igneous contact between two intrusions of massive KGd. The contact is marked by a gradational increase of K-feldspar megacrysts upwards towards the contact and with an abrupt reduction of K-feldspar phenocrysts across the contact. The long axes of K-feldspars are aligned parallel to the contact, interpreted as magmatic alignment. Photo also exemplifies the local heterogeneity of the Minto pluton, with KGd varying from granodiorite (Gd) at the bottom of the photograph upwards to syenite (Sy), then abruptly back into granodiorite. B. A weakly chlorite-epidote-magnetite-pyrite altered enclave of KGd within an unaltered KGd host, suggesting a history of intrusion interspersed with  28  hydrothermal alteration. Note the magmatic alignment of K-feldspar along the enclave margin. U-Pb dating of zircon using the SHRIMP indicates crystallization ages of 200.1 +/- 1.1 Ma for the enclave and 197.6 +/- 1.6 Ma for the host (see Geochronology). C. KGd intruded along a strongly deformed and altered KGd. This intrusion has stoped an enclave of the pre-existing deformed KGd into the younger KGd. Pre-existing structural fabircs were also crosscut by Tlt, e.g., biotite foliation (Figure 9C) and gneissic layering (Figure 9D). Pre-existing structural fabircs were also crosscut by Tlt, e.g., biotite foliation (Figure 9C) and gneissic layering (Figure 9D).  29  Figure 9: Photos showing crosscutting relationships involving intrusions of Tlt which indicate multiple stages of intrusion. A. Subtle igneous contact between KGd and Tlt marked by a contrast in bulk mineralogy and grainsize, i.e., lack of K-feldspar, abundant hornblende, and coarser grainsize within Tlt. Sample H587-252.5. B. Apparent igneous contact between KGd and Tlt marked by a contrast in bulk  30  mineralogy and grainsize. Sample H424-252(c). C. Igneous contact between Tlt and a deformed and altered granitoid indicating intrusion after the development of biotite foliation. Note that the igneous contact in this case is irregular and marked by short intrusions along foliation planes. This enclave of Tlt is a boudin within a larger section of foliated KGd, indicating intrusion before the cessation of ductile deformation. Boulder taken from blast heave in the Minto pit. D. Igneous contact between Tlt and a strongly deformed, compositionally banded granitoid. The Tlt host rock is folded, indicating intrusion after multiple stages of deformation, and altered (quartz-magnetite-chalcopyrite-bornite). Boulder is from high grade stockpile, mined from the Minto pit.  31  2.2.3  Lithogeochemistry of KGd  The bulk chemistry and trace element concentrations of granitoids are a useful means of interpreting the tectonic setting and conditions during granitoid petrogenesis. In this study whole rock lithogeochemistry also serves as a protolith benchmark to assess the metasomatism associated with the Cu-Au mineralisation at Minto. A suite of ten KGd samples was collected across the Minto pluton (Table 2, Appendix C ) for lithogeochemical analysis along a roughly East-West transect. KGd was chosen because it is interpreted as the most common protolith for deformed ore-bearing rocks at the Minto deposit. The sample suite consists of five fresh samples collected from drillcore and five samples taken from surface. Weathering effects for surface samples were reduced by removing weathering rinds using a rotary saw. Samples were analysed using a combination of lithium metaborite/tetraborate fusion inductively coupled plasma mass spectrometry (FUS-ICP) and instrumental neutron activation analysis (INAA) by Actlabs (Ancaster, Ontario; method 4LITHORESEARCHQUANT). Results and detection limits for this assay package are listed within Appendix B and are typically in the low ppm and ppb range for trace elements. In addition to the use of laboratory standards, selected samples were split and both aliquots were analysed as a means of quality control. Quality control for analyses are also given in Appendix C .  32  Table 2: Geochemical sample information. Geochemical data in Appendix C . ND = not described by Tafti (2005) Researcher Hood (this study)  Tafti (2005)  Sample  Weathering  UTM E  UTM N  H424-212  Fresh  384531.1  6944491  H424-252  Fresh  384531.1  6944491  H424-323  Fresh  384531.1  6944491  H510-64  Fresh  383202.1  6945821  H587-253  Fresh  384140.5  6945938  S09-02-9A  Weathered  383776  6945758  S09-08-01A  Weathered  382654  6944715  S09-15-04A  Weathered  387024  6946222  S09-16-01D  Weathered  384724  6945250  S09-22-01C  Fresh  384535  6945018  01-12-282.5-283  ND  ND  ND  01-13-162-163  ND  ND  ND  01-8-113-114  ND  ND  ND  01-9-256  ND  ND  ND  02-RT-2  ND  ND  ND  93-A-169-170  ND  ND  ND  93-A-205.3  ND  ND  ND  93-A-326-327  ND  ND  ND  93-B-302-304  ND  ND  ND  93-E-476-477  ND  ND  ND  93-G-236-237  ND  ND  ND  96-4-285-286  ND  ND  ND  99-6-108-109  ND  ND  ND  33  2.2.3.1  Results  The weight percentage of major rock forming elements for KGd in this study are within the range of values described by Tafti (2005, figure 10), e.g., in terms of total Na2O + K2O versus SiO2 (as per Cox et al., 1979) Concentrations of Y+Nb vs. Rb (Figure 11A) suggest granitoids were generated in a continental magmatic arc, i.e., volcanic arc granite field (after Pearce and Norry, 1979). Alumina saturation plots (Figure 11B) indicate Minto granitoids are strongly peraluminous. Modified alkali-lime saturation plots (MALI, Figure 11C) of KGd show most rocks within the calc-alkalic zone, with several surface samples within the calcic field, possibly attributable to weathering. KGd plots within the magnesian region of a Fe Index plot (Figure 11D).  34  Figure 10: Whole-rock lithogeochemical granite type discrimination diagram based on total alkalis versus total silica (TAS) (Cox et al., 1979) modified after (Middlemost, 1994) placing KGd within the quartz diorite/granodiorite field. Quartz diorite and granodiorite are grouped because the geochemical classification of volcanic rocks using total alkali versus silica cannot reproduce QAPF parametres (Bas et al., 1986; Le Maitre, 1989). Classification is on a non-genetic basis and intended to be consistent with classification of volcanic rocks using modal mineral content, i.e., quartz-alkali feldspar-plagioclase-foidite (QAPF, after Streckeisen, 1974). Two samples from Tafti (2005) plot as syenodiorite, while the remainder plot in a similar location to KGd sampled in this study.  35  Figure 11: Whole rock lithogeochemical characterization of KGd using trace elements. A. Tectonic discrimination diagram (Pearce et al., 1984) indicating KGd plots within the volcanic arc granite field (VAG). Other abbreviations represent orogenic granites (ORG), syncollision granites (syn-COLG), and  36  postcollision granites (post-COLG) granitoids. B. Aluminum saturation plot (Roser and Korsch, 1988) placing KGd within the strongly peraluminous field. C. Peraluminous rocks may be calcic, alkali-calcic, or calc-alkalic (Frost et al., 2001). Modified alkali-lime (MALI) plot of Na2O + K2O – CaO vs. SiO2 (after Frost et al., 2001; Frost and Frost, 2008) indicates KGd from this study clusters near the Calc-alkalic to Calcic boundary but is dominantly calc-alkalic. D. KGd from this study plots as magnesian according to the Fe Index plot (after Frost et al., 2001; Frost and Frost, 2008), and therefore oxidized. Fe* is defined as [FeTot/(FeTot + MgO)]. Boundary line (modified Fe* trend) is a continuous line defined by Fe* = 0.46 + 0.005 SiO2 (Frost and Frost, 2008).  37  2.3  Mineralisation and Alteration  Mineralisation and associated alteration at Minto is mainly coincident with variably developed shear zones. For this study field mapping, core logging, petrographic observation, and geochemical analysis are used to characterize hydrothermal alteration in the Minto deposit. Samples for study were collected from regional outcrop, the open pit, and from exploration drillcore. 2.3.1  Ore Assemblage  The hypogene ore minerals of the Minto deposit are bornite and/or chalcopyrite, with Au and Ag occurring as microscopic inclusions within Cu-sulphides. These economic minerals occur in the following assemblages : (i) bornite, (ii) bornite-chalcopyrite, (iii) chalcopyrite, (iv) chalcopyrite-pyrite, and (v) pyrite. Assemblages grade laterally and vertically, a feature first noted and mapped by Pearson (1979). Chalcopyrite and bornite are fine- to medium-grained and disseminated amongst biotite (Figure 12A). Contacts between Cu-sulphides and biotite or magnetite are typically straight (Figure 12B), although the interpretation of sulphide textures as evidence of relative timing between sulphide types, exsolution conditions, metasomatism, or remobilization is extremely unreliable owing to the overprint of ductile deformation and thermal re-equilibration. Exsolution textures of chalcopyrite from bornite, and possibly vice-versa, are present in approximately 75% of mineralized samples. Sharp, wedge-shaped lamellae are interpreted as having not been deformed, although a genetic cause is not clear, as they may form during sulphide precipitation, during cooling, as a result of re-heating, due to replacement, or due to metamorphism (Brett, 1964; Gill, 1969; Durazzo and Taylor, 1982). These exsolution lamellae may also have a vermicular or myrmekitic geometry, a texture suggestive of thermal  38  annealing and re-equilibration (Brett, 1964; Durazzo and Taylor, 1982). Mineralisation tends to occur within biotite-dominated foliation, but biotite-chalcopyrite-bornite also occur as stringers or veins (Figure 12C) with little evidence of deformation. Pyrite (Figure 12D) is present as fine to coarse grains disseminated or as anhedral masses. Quartz veins (Figure 12E.) are rare and chalcopyrite and bornite tend to occur along margins. More common are silicified zones (Figure 12F) bearing sulphides, magnetite, and biotite. Chalcopyrite and bornite are locally present as inclusions within weakly zoned Mn-Ca-Fe garnets (Figure 12G), although chalcopyrite was also observed to overprint garnets (Figure 12H).  39  40  Figure 12: Photographs and photomicrographs of hypogene mineral assemblages related to sulphide mineralization. A. Fine to medium grained chalcopyrite and/or bornite is the most common and widespread mineralization style at Minto. Mineralization tends to terminate abruptly at structural contacts, although millimeter-scale blebs of chalcopyrite and bornite were observed within massive rocks up to several centimetres from contacts (inset). B. Micrograph of contact between chalcopyrite, bornite, biotite, and magnetite showing sharp intermineral boundaries. Plane polarized plus incident light. Sample SBH-C042B-B. C. Photograph of chalcopyrite with minor bornite occurring as coarse grained blebs coincident with medium-coarse grained biotite-magnetite alteration. Sulphides are also present as disseminated fine grains throughout the rest of the sample. Sample SBH-C039. D. Pyrite at Minto is relatively uncommon compared to chalcopyrite and bornite. Pyrite may occur alone or with chalcopyrite, generally correlated with biotite alteration. Sample H510-276. E. Quartz vein with coarse grained chalcopyrite-bornite and epidote-hematite along margins. Quartz veins are uncommon at Minto and are not obviously correlated to mineralization. F. Folded and boudinaged zone of silicified rock hosting disseminated  chalcopyrite-bornite-magnetite.  Siliceous  Cu-sulphide  zones  are  associated  with  chalcopyrite-bornite rich regions and strong biotite-magnetite alteration. G. SEM backscatter micrograph of Ca-Mn-Fe garnet with rounded chalcopyrite inclusions. Magnetite is also a common inclusion in these garnets. Sample H587-233. H. Chalcopyrite overprinting fractured Ca-Mn-Fe garnet. Sample H510-276. I. Disseminated molybdenite overprinted by propylitic alteration, manifested as chloritization of biotite and pervasive pink hematite staining of plagioclase. The molybdenite in this sample was dated at 197.4 (+/- 0.8) Ma using Re-Os geochronology and is discussed in the Geochronology section of this thesis. Sample H429-153. J. Weakly deformed molybdenite with inclusions of chalcopyrite. Molybdenite at Minto appears to post-date Cu-sulphide mineralization. Micrograph taken under reflected light. Sample 08SH-C028.  41  Minor molybdenite was observed in drill core across the Minto deposit as fine- to coarsegrained blebs. Molybdenite was most commonly disseminated within granitoid host-rocks (Figure 12I), although it was also observed as hosted within quartz-gypsum veins or quartzofeldspathic dikelets. Reagrdless of the mineralization style, molybdenite consistently crosscut bornite, chalcopyrite (Figure 12J), and pyrite, and is in turn overprinted by propylitic alteration. Three samples for Re-Os geochronology were chosen from across the deposit and are described further in 2.4.5, Geochronology. Based on copper, gold, and silver assays from the across the Minto deposit, hypogene mineralisation appears to be approximately collinear (Figure 13). Whether this relationship between elements is due from co-genetic precipitation or from multiple overprinting mineralisation events was not determined, but the relationship indicates copper grade as a useful proxy for gold and silver when mapping mineralisation.  42  Figure 13: Plots of metal tenor using company geochemical data (Captone Resources dataset, unpublished) suggest an approximately linear correlation between Cu and Au (A.), and Cu and Ag (B.), making copper a useful proxy for other economic metals at Minto when mapping or creating cross sections. Data has been filtered in an attempt to show only assays where hypogene mineralization is present. Intervals have removed where metals are not present and when the ratio between Cu NS (nonsulphide hosted copper) and Cu is greater than 0.15, i.e., zones of supergene enrichment.  43  2.3.2  Alteration Assemblages  Potassic alteration is the most common alteration type present at Minto. It is largely defined by secondary biotite and magnetite. This potassic alteration is present in essentially all foliated granitoids and may constitute up to 10-25% of the rock, usually as anastomosing folia (Figure 12A) but locally as foliation parallel veinlets (Figure 14A). Biotite crystals range in size from sub-millimetre to several millimetres and shares sharp crystal faces with euhedral to subhedral fine- to medium- grained magnetite (Figure 14B). Quartz associated with biotite-magnetite occurs as siliceous zones. Chalcopyrite + bornite can comprise up to 10% of these zones, magnetite and biotite up to 1%, with minor plagioclase also present.  44  Figure 14: Photomicrographs showing selected alteration assemblages. A. Foliation parallel veinlet of biotite-magnetite alteration crosscut by veinlet of iron oxide-carbonate. B. Biotite-magnetite alteration showing sharp contacts between phases. Sample SBH-C100-C. C. Fracture controlled propylitic alteration (marked with a white arrow). Pink selvage is hematite-stained plagioclase. Biotite and hornblende within selvage margin are altered to chlorite. D. Pervasive propylitic alteration consisting of chlorite-hematite-Fe carbonate assemblage crosscutting copper sulphides and controlled by brittle deformation.  45  Secondary magnetite within potassically altered zones increases the magnetic volume susceptibility of rocks, typically to the hundreds of kappa (dimensionless SI units of Am1  /Am-1 10-3) range. In contrast, a typical magnetic volume susceptibility measurement for  KGd is between 0 and 5 kappa. Thus magnetic-susceptibility is a useful quantitative proxy for the degree of potassic alteration. Relatively late propylitic alteration is widely distributed across the Minto deposit and is characterized by chlorite +/- epidote +/- calcite +/- hematite dusting of feldspars +/- fine hematite veining. Hornblende and/or biotite are variably converted to chlorite +/- epidote +/titanite +/- hematite +/- pyrite. Hematite dusting of plagioclase is extremely common, and the resulting pink to pink-orange colouration may lead to easy misidentification as K-feldspar. Propylitic alteration is controlled by fractures, i.e., joints and microfractures. The scale and pervasiveness of this alteration ranges from micrometre sized intergranular fluid pathways, to millimetre/centimetre selvages along fractures (Figure 14C), to several metres of pervasive alteration (Figure 14D). Fractures crosscut massive KGd, shear zones, shear zone boundaries, and igneous contacts. An earlier stage of propylitic alteration has locally been crosscut by later granodiorite intrusions (Figure 8B). Crosscutting and intergranular carbonate veining is present throughout the Minto deposit. Habit ranges from intra-biotite grain infill to <0.25 - 1 mm veins. Crystals are blocky, equigranular, and polygonal up 0.2 mm, to equigranular finegrained anhedral crystals 10 µm. Rarely, both phenotypes of crystal are present in a vein, finer-grained crystals being restricted to one margin of the vein and grading to coarser size. Veins tend to be oriented parallel to foliation in foliated zones, and in various sub-parallel orientations oblique to foliated/non-foliated contacts in massive granitoids. Fine-grained sericite is locally developed with plagioclase and ranges in intensity from weak to nearly  46  complete. Moderately to strongly saussuritized plagioclase appears blue-green in hand specimen. Epidote veining was observed in all igneous rocktypes. Veins range from submillimetre to several millimetres. “Bleached” selvages are common, possibly due to argillization of plagioclase, and contain chloritized biotite/hornblende and hematite dusting of plagioclase. Minor pyrite was locally observed within the margins of the vein. Late supergene alteration has locally altered Cu-sulphides to chalcocite, tenorite, malachite, and azurite. This alteration has produced economic supergene mineralisation in areas of Minto, but is not discussed further in this text. 2.3.3  Evaluating Mass Transfer  The nature and scale of mass transfer associated with Cu-Au mineralisation was evaluated using whole rock lithogeochemistry on a suite of mineralized foliated to massive nonmineralized and non-altered granitoids from across the Minto property. Questions to be examined include whether the foliated-mineralized rocks could be derived from the massive units through progressive foliation development and hydrothermal alteration/metasomatism, whether mineral assemblages interpreted as hydrothermal could have indeed arisen from mass addition or mass subtraction, whether there has been mass increase or decrease in altered rocks, and whether there is a variation in mass transfer patterns between samples representing different ore mineralogy. 2.3.3.1  Analytical Techniques  Thirty-eight samples were collected from regional outcrops, pit benches, and drill core for whole-rock geochemical analyses of major, trace, and rare earth elements (Figure 15). Samples represent a variety of Minto granitoids and include examples of massive, variously deformed, and variously altered rocks. All samples were trimmed using a rotary saw to  47  minimize the effects of weathering and were analysed at Activation Laboratories Ltd. in Ancaster, Ontario. Fusion inductively coupled plasma (FUS-ICP) was used for the following elements and oxides: SiO2, Al2O3, Fe2O3 (T), MnO, MgO, CaO, Na2O, K2O, TiO2, P2O5, Sc, Be, V, Sr, Ba. Fusion mass spectroscopy (FUS-MS) was used for the following elements: Cr, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Y, Zr, Nb, Mo, Ag, In, Sn, Sb, Cs, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th, U. Instrumental Neutron Activation Analysis (INAA) was used for the following elements: Au, As, Br, Cr, Ir, Sc, Se, Sb. Finally, percent copper was measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Geochemical results are presented in (Table 3).  48  Figure 15: Location of regional and drillhole samples selected for geochemical comparison. Transect AA’  geochemical samples overlayed on orthophoto of the Minto deposit. Base photo sourced from  Capstone Resources database.  49  Table 3: Lithogeochemical sample information from samples collected during 2009 field season. Geochemical data listed in Appendix D . KGd = K-feldspar granodiorite, Tlt = tonalite, BGn = banded gneiss, unk = unknown, Bt = biotite, Mag = magnetite, Cpy = chalcopyrite, Bn = bornite, Py = pyrite, Gnt = garnet, Qtz = quartz, Si = silicification, Weath = weathered. Sample  UTM E  UTM N  H424-212  384531  H424-224  384531  H424-252 H424-314  Elev  Lith  Def'd  Alteration  6944491  KGd  No  NA  6944491  KGd  Typical  Bt, Mag, Cpy  384531  6944491  KGd  No  NA  384531  6944491  KGd  Typical  Bt, Mag, Cpy, Bn  H424-323  384531  6944491  KGd  No  NA  H427-115  384956  6943813  KGd  Typical  Bt, Mag, Cpy  H427-124  384956  6943813  KGd  No  NA  H427-125  384956  6943813  KGd  Typical  Bt, Mag, Cpy, Py  H427-131  384956  6943813  KGd  No  NA  H427-70  384956  6943813  KGd  Typical  Bt, Mag, Cpy, Bn  H510-64  383202  6945821  KGd  No  NA  H587-141  384141  6945938  KGd  No  NA  H587-233  384141  6945938  KGd  Typical  Bt, Cpy, Gnt  H587-253  384141  6945938  KGd  No  NA  S09-02-9A  383776  6945758  960  KGd  No  NA  S09-08-01A  382654  6944715  1007  KGd  No  NA  S09-08-04A  381289  6944784  884  KGd  No  NA  S09-10-03B  391014  6947669  625  KGd  No  NA  S09-13-03A  386926  6946023  760  KGd  No  NA  S09-13-03B  386926  6946023  760  KGd  No  NA  S09-13-03C  386926  6946023  760  KGd  No  NA  S09-14-01Bi  384590  6945165  730  KGd  BGn  Qtz vein? Si, Bt, Mag, Cpy, Bn  S09-14-01Bii  384590  6945165  730  KGd  Def  Bt, Mag, Si, Cpy, Bn  S09-15-04A  387024  6946222  767  KGd  No  NA  S09-16-01A  384724  6945250  825  KGd  BGn  Weath. Bt, Mag, Cpy, Bn, Si  S09-16-01B  384724  6945250  825  KGd  No  NA  S09-16-01C  384724  6945250  825  KGd  Typical  Bt, Mag, Cpy, Bn  S09-16-01D  384724  6945250  825  KGd  No  NA  S09-17-05A  388739  6947539  747  KGd  No  NA  S09-22-01A  384535  6945018  730  Tlt  BGn  Bt, Mag, Cpy, Bn  S09-22-01B  384535  6945018  730  KGd  unk  Bt, Mag, Cpy, Bn  S09-22-01C  384535  6945018  730  KGd  No  NA  S09-24-02Ai  384539  6945075  730  Tlt  unk  Bt, Mag, Cpy, Bn  S09-24-02Aii  384539  6945075  730  Tlt  unk  Qtz vein? Si, Bt, Mag, Cpy, Bn  S09-25-02B  384633  6944928  730  KGd  BGn  Bt, Mag, Cpy, Bn  50  2.3.3.2  Isocon Plots  Whole rock geochemical data only show relative changes in bulk rock chemistry (Gresens, (1967). For example, a rock that has been extremely enriched in SiO2 during deformation will show much larger concentrations of all other elements relative to its protolith. This can be corrected by normalizing element concentrations to the inferred immobile elements in the protolith. Some elements can be essentially immobile during deformation and alteration depending on factors such as fluid composition, host rock composition, and deformation environment (e.g., Streit and Cox, 2002). Gresens (1967) designed a mathematical method to estimate changes in rock volume and concentrations of elements during metasomatism. In Gresens’ (1967) method the likely immobile components during alteration are used to identify any volume change associated with the alteration. If it is assumed that volume change is a factor common to the behavior of all components, it is possible to calculate gains or losses of the other components. Mass gains and losses are calculated using the following relationship: Xn = [Fv(Sb/Sa)Cbn – Can] x 100, where Xn = is the mass gain or loss for component n, Fv is the volume factor, Sb is the specific gravity of the altered sample, Sa is the specific gravity of the unaltered sample (i.e., protolith), Cbn is the concentration of component n in the altered sample, and Can is the concentration of component n in the unaltered sample. Grant (1986) presented a mathematically similar graphical method to solve Gresens’ (1967) equation called the isocon method. A review of the isocon method was published by Grant (2005) and is applied in this thesis. The isocon method uses a plot of the geochemical composition of an altered rock against that of its protolith. In the ideal case, immobile elements will define a straight line through the origin, the isocon, defined by: C A =  51  (M0/MA)C0, where CA is the element concentration in the altered rock, C0 the element concentration in the fresh rock, and the slope is defined by the ratio of equivalent masses (M0/MA) in the fresh and the altered rock (Grant, 1986). Hence, the slope indicates mass gain (slope > 1) or mass loss (slope < 1) during alteration of the protolith. Three suites of KGd and altered KGd were selected from drill core and the open pit. Seven samples of KGd in these suites are interpreted as representative least-altered protoliths for adjacent altered rocks. To assess this interpretation these samples were compared to other KGd sampled across the Minto pluton and from a pre-existing study (Tafti, 2005) and all exhibit similar normalized chondrite plots of KGd (Figure 16). KGd from sample suites was then averaged, as per Grant (2005), to reduce the effects of protolith heterogeneity, minor alteration, or weathering effects. This averaged protolith serves as the geochemical baseline for nine samples of deformed sulphide bearing granodiorite with potassic alteration, further subdivided based on sulphide assemblages into bornite-chalcopyrite, chalcopyrite, and chalcopyrite-pyrite groups. Elements to be plotted on the isocon diagram were chosen by (i) selecting elements that appear to be least mobile based on plots of elements against each other (Figure 17), and (ii) elements characteristic of the main mineral assemblages described above. Element values were then scaled as described by Grant (2005) to best produce a clear representation of the data, i.e., elements with small values will plot close to the origin relative to elements with high concentrations. Grant (1986) selected the isocon by arbitrarily scaling the concentration values for each element so as to obtain a reasonable distribution of the data points on the isocon plot. The slope of the isocon may be determined as described by Grant (2005) from: (a) clustering of CiA/CiO data, (b) the best fit of data forming a linear array through the origin  52  on an isocon diagram (the graphical equivalent of the first method), (c) the a priori assumption that certain elements are immobile, (d) the assumption of constant mass during alteration, or (e) the assumption of constant volume during alteration. Certain elements are more commonly more immobile than others (Grant, 1986; O'Hara and Blackburn, 1989; Glazner and Bartley, 1991; Tobisch et al., 1991; Marquer and Burkhard, 1992; Prochaska et al., 1992), however it is necessary to confirm relative immobility on a case by case basis. High field strength elements (HFSE) like Al2O3, TiO2, Zr and Hf and most REE, like La and Yb, are considered immobile in most hydrothermal systems (e.g. Leitch and Lentz, 1994).  53  Figure 16: Spider diagrams comparing samples used in isocon study, samples collected regionally, and samples previously analysed by Tafti (2005) showing that the averaged bulk geochemistry of each sample suite is within 1-sigma overlap of one another. This similarity suggests that the averaged protolith suite used for isocon analysis is representative of averaged KGd composition across the Minto pluton even though there is local mineral heterogeneity within the pluton. Element values have been normalized to the Cl chondrite values of McDonough and Sun (1995). Blue points represent seven samples of KGd taken proximal to altered samples used for isocon study. Green points represent samples taken from across an east-west transect of the Minto pluton. Grey points represent thirteen samples taken from unpublished thesis data (Tafti, 2005) and represent a mix of fresh and weathered rocks.  54  Figure 17: Plots for altered and protolith samples of KGd, measured using whole rock lithogeochemistry (Table 2), were plotted with Ti, Hf, Zr, and V being interpreted as the most likely candidates for immobility during alteration/deformation. Assessment of immobility is based on elements with consistent relative abundances in the protoliths and altered/deformed rocks plot as clusters or overlapping linear trends (after Finlow-Bates and Stumpfl, 1981). Analytical uncertainties are given in Appendix D  55  For this study, concentrations of elements in protolith and biotite-magnetite-sulphide samples were plotted against each other to determine potential immobility (Figure 17, following Finlow-Bates and Stumpfl 1981), with Hf, Zr, V, and Ti emerging as the most likely candidates. These elements then served as the basis for an isocon, with results shown in Figure 18. Elements that have been enriched plot above the isocon, and those that have been depleted plot below the isocon. For the Cu-sulphide, biotite-magnetite bearing granodiorites in this study, K2O, Fe2O3, P2O3, U, Th, and Pb appear to have been added. Depleted elements include SiO2, Al2O3, CaO, Na2O, and Sr. The addition of K and reduction of Na and Ca in these samples is consistent with literature involving potassically altered rocks (Giggenbach, 1984). Mn generally appears to have been depleted from these rocks, although one sample containing Mn-rich garnet plots above the isocon. The remaining plotted elements MgO, Pb, Lu, Gd, Sc, Ce, and La plot both above and below the isocon. This may be due to variation of these elements in the protolith or varying enrichment or depletion in the samples.  56  57  Figure 18: Isocon diagram illustrating relative enrichment and depletion of major element oxide (wt %) and trace element (ppm) concentrations in the Minto Granodiorite. X-axis = representative least altered sample averaged from twenty-one samples of least-altered KGd, Y-axis = altered sample. Altered samples are all deformed versions of KGd with sulphide mineralization plus magnetite-biotite (potassic) alteration. Data are scaled for portrayal as described by Grant (2005). The mass conservation line has slope = 1 and is a reference isocon indicating equal concentrations in least altered and altered rock. Isocon line is a reference isocon assuming Ti, Hf, Zr, and V have been immobile during alteration (Grant, 1986; O'Hara and Blackburn, 1989; Glazner and Bartley, 1991; Tobisch et al., 1991; Marquer and Burkhard, 1992; Prochaska et al., 1992). Data above this line may represent element enrichment, and data below this line may represent element depletion to least-altered rock. The grey zone is bounded by the greatest spread of immobile element values and represents the spread of potential isocon slope error due to element heterogeneity in the least-altered sample.  58  There has been debate about the most accurate method for isocon placement, e.g., fitting by eye (Grant, 1986, 2005), least-squared regression (Baumgartner and Olsen, 1995), or error bars (Baumgartner and Olsen, 1995). This debate is centered around the difficulty in choosing an accurate isocon due to natural variation, e.g., heterogeneity of immobile elements amongst samples of a protolith. This effect is pronounced when examining granitoid rocks, where minerals may be fractionated within rocks although overall geochemistry is similar. Immobile elements in this study do vary within the protolith, illustrated by points not plotting in the same position. A conservative interpretation of what elements have been enriched or depleted may be made if an “isocon region” is constructed by including the area covered by the greatest spread in immobile element concentrations. In theory, any elements plotting above or below the isocon region show variation due to mass transfer to an extent greater than any variation inherent to the protoliths. In this case it appears that K2O and Th have definitely been added to rocks, while Na2O and Sr have definitely been depleted.  59  2.4  Structural Geology  The Minto pluton comprises multiple intrusive phases as observed through cross-cutting relationships between granitoids and granitoid dikes. Magmatic flow fabrics are common and developed heterogeneously within granitoids through the pluton. In addition, all granitoids show fabrics indicating solid state deformation, varying from incipient recrystallization microtextures to the development of mylonitic foliations. This ductile deformation is concentrated into discrete shear zones coincident with hypogene Cu-Au-Ag mineralisation and associated alteration. At least two varieties of rock fabric are recognized within Minto granodiorites and represent end members of fabric development: magmatic fabrics (discussed in Section 2.2.2) and solidstate recrystallization fabrics. Purely magmatic fabrics are developed within intrusive rocks above the solidus, e.g., dimensional-preferred orientation of K-feldspar megacrysts in KGd as the result of non-hydrostatic stress in flowing magma (Vernon and Paterson, 2008). Magmatic fabrics involve the rotation and/or settling of crystals in a melt matrix, and filter pressing of melt from between crystals, however these physical processes are only possible where the melt to crystal fraction is high; above 60-80% crystals it is difficult to rotate crystals and magmatic foliation can be “frozen in”. Interpreting the relative timing between pluton crystallization and regional deformation is a complex problem because of the changing rheology of magma as it crystallizes, and because of the incomplete understanding of the range of fabric development created during the transition from magma to crystalline solid and during emplacement (e.g., Paterson, 1989). For example, crystallization dynamics and related igneous fabrics have been modeled for magma chambers where regional stress is absent (e.g., Bea, 2010), although it is widely  60  believed that regional deformation is a common factor during pluton emplacement (e.g., Brown and Solar, 1998). 2.4.1  Solid State Microstructures  The most prominent structural feature of host rocks at Minto is a typically shallow dipping (0º-30º) penetrative solid state foliation (SP) that occurs in discrete shear zones bounded by granitoids that appear massive in hand specimen. The intensity of solid state deformation and the associated development of the SP foliation grades out from the shear zones into the relatively non-deformed massive granitoids. This gradient in strain intensity is largely unaffected by any overprinting penetrative deformation and provides a spatial analogue for progressive foliation development. The gradient in the intensity of SP has been divided into four stages on the basis of relative degrees of solid state recrystallization of quartz, plagioclase, and K-feldspar. The four levels of deformation are (i) incipient deformation, (ii) weak foliation, (iii) typical penetrative foliation, and (iv) mylonitic, i.e., highly deformed. 2.4.1.1  Stage 1: Incipient Deformation  “Massive” granitoids that make up much of the Minto pluton are incipiently deformed and exhibit textures indicative of intracrystalline deformation and recovery/recrystallization that overprint primary igneous textures. These textures, though visible in thin section, are not evident in hand specimen (Figure 19A and B). K-feldspar, plagioclase, quartz, and biotite, all have textures indicative of incipient solid state deformation, including deformation lamellae and twins, grain boundary bulges, and marginal K-feldspar myrmekite development (Simpson and Wintsch, 1989).  61  62  Figure 19: Photographs showing hand samples of deformed KGd where grainsize is progressively less. Thin sections show an increasing amount of deformation textures with decreasing grain size. A. Incipient deformation is not observable in KGd at hand specimen scale. B. Minor solid-state recrystallization microtextures characterize incipient deformation and are evidence of strain accommodated by the Minto pluton as a whole. Microtextures include the beginning of core-and-mantle textures, minor myrmekite  63  development along K-feldspar margins, slight undulose extinction in quartz and feldspars, and tapered lamellae in plagioclase slightly overprinting growth lamellae. C. Weakly deformed KGd exhibits discontinuous and disjunctive biotite foliation that anastomoses around feldspar grains. K-feldspar is commonly fractured. Quartz may form flattened masses, especially where quartz eyes are present. D. In thin section weak deformation is also exemplified by moderate myrmekite development along K-feldspar margins. Minor recrystallization of quartz and plagioclase creates fine-grained mantles of recrystallized material around cores of larger relict feldspars. E. Moderately deformed KGd is the most common structural unit at Minto. Ductile deformation textures are more strongly developed and relict internal igneous textures in igneous minerals are rare. Quartz and plagioclase have undergone significant grain size reduction. Quartz and plagioclase exhibit solid state intracrystalline deformation textures with weak lenticular shapes aligned with SP, whereas K-feldspar tends to experience grain size reduction by fracture first, then ductile deformation. G. and H. Strongly deformed KGd sharing a structural contact with incipiently deformed KGd, defined by an abrupt reduction in grain size. Deformation intensity is highest near the contact, and the deformation zone partially penetrates massive rock. Very fine grained chalcopyrite and magnetite are present in the high strain zone but not in the incipiently deformed rock.  64  2.4.1.2  Stage 2: Weak Foliation  As the intensity of SP progresses, solid state deformation fabrics are more pronounced and become visible in hand specimen (Figure 19C and D). Stage 2 deformation is considered to begin when structural fabrics are recognizable in the field. In this stage biotite becomes progressively aligned into discontinuous to continuous anastomosing folia. Marginal recrystallization of plagioclase and quartz into the foliation plane gives these porphyroclasts a slightly lenticular shape. K-feldspar is commonly fringed by fine-grained myrmekite and crosscut by parallel, “domino” style, fractures oblique to the surrounding foliation. Quartz eyes are recrystallized to quartz ribbons that become progressively flatter in tandem with more strongly developed solid state deformation microstructures described above. Finegrained plagioclase and quartz mantle larger plagioclase and K-feldspar grains creating a core-and-mantle texture. Undulose extinction within quartz and biotite is also more common, and the boundaries between these minerals are more undulatory. 2.4.1.3  Stage 3: Well Developed Penetrative Foliation (SP)  Progressive foliation development eventually leads to the near total recrystallization and variable degrees of grain size reduction of all the primary igneous minerals (Figure 19E and F). This stage is considered to begin where deformation, i.e., SP, is readily measurable in the field. K-feldspar augens, representing relict K-feldspar megacrysts, are typically similar in grain size to plagioclase and quartz grains and deform entirely by recrystallization. This may be due to previous grain size reduction by brittle fracture to a point at which recovery and recrystallization can relieve internal strain energy at the strain rate and temperature conditions of the shear zone (e.g., Vernon et al., 1983). Additionally, hydrothermal fluids channelled through the deformation zones may hydrolytically weaken K-feldspar (Yund and  65  Tullis, 1980; Tullis and Yund, 1985). Plagioclase and quartz also deform ductiley, and grain boundaries are increasingly undulatory with prominent grain boundary bulge development. Biotite is progressively more aligned, resulting in more continuous folia, and anastomoses feldspar rich microlithons. Unlike feldspars and quartz, the grain size of biotite does not appreciably decrease at this stage. Individual grains within foliation are not necessarily foliation parallel, and extinction angles also vary. The degree of biotite foliation development is linked to its relative abundance, and it should be noted that rocks with abundant hydrothermal biotite are preferentially deformed. Interestingly, hornblende was not observed in deformed rocks, suggesting that deformation zones are coincident with zones of hydrothermal alteration and that hornblende is no longer stable. 2.4.1.4  Stage 4: Mylonitic Foliation  Mylonitic foliation is developed both within larger deformation zones and crosscutting otherwise massive granitoids. This stage is separated from previously described stages based on abrupt strain transitions juxtaposing very fine-grained mylonite with more coarsely grained rocks, and by the consistent grain size reduction of bulk minerals (Figure 19G and H), typically quartz, feldspars, epidote, and magnetite. Deformation microtextures are identical to those in SP, i.e., textures arising from solid state recrystallization of constituent minerals. This is consistent with interpretations by Hickey and Bell (1996) that mylonitic foliations represent a final metastable grain size substantially smaller than that in less highly strained rocks. Mylonitic zones are present as bands up to several centimetres in scale. These zones are generally within larger, less deformed zones and parallel to the adjacent foliation. Less commonly mylonite foliation was observed to crosscut massive of deformed granitoids at  66  moderate to steep orientation. In otherwise massive host rocks, grain size reduction of original mineralogy is significant. Small zones of steeply oriented (50º-80º) mylonitic zones crosscut massive and deformed granitoids. When cutting deformed zones, SP is rotated into the overprinting zone of mylonitic foliation. Disseminated and deformed magnetite and sulphide minerals, including chalcopyrite and bornite, are common in mylonite zones, including mylonitic zones crosscutting massive unmineralized granitoids. 2.4.2  Gneissic Banding  Granitoid gneisses (Figure 20) exhibit compositional layering of light bands of dominantly quartz +/- hematite-stained plagioclase +/- K-feldspar, and dark bands comprising dominantly quartz +/- magnetite +/- biotite. Chalcopyrite and bornite are common accessory minerals in the rock, mainly within dark bands, and are either disseminated or variously deformed. Zones of this banded rock occur bounded by massive KGd, as discrete zones within larger zones of deformed KGd, and as small zones sharing gradational contacts with surrounding deformed KGd. These banded rocks are interpreted as a product of deformation overprinting KGd, where the host has been altered and likely intruded by felsic dikelets, as shown in Figure 5. Compositional segregation and a well developed foliation observed at hand specimen scale suggest banded rocks are equivalent to Stage 3, described above. Quartz and plagioclase grains tend to be larger than those in strongly deformed rocks, and all grains are anhedral.  67  Figure 20: Photographs showing compositional banding in KGd. A. A typical sample of gneissic banding at Minto taken from a high-grade zone in the Minto open pit. SP is defined by mainly by compositional banding and biotite foliation is minor, in contrast with other deformed rocks. Bands are typically pink and black, composing recrystallized quartz (Qz), plagioclase and K-feldspar (feld), magnetite (Mag), chalcopyrite (Cpy), and bornite (Bn). Feldspar is volumetrically higher in pink bands, whereas quartz, magnetite, and sulphides are dominant within black bands. B. Compositional banding is interpreted as produced by the rotation and folding of pegmatite dikelets (Def’d Pglt) into the plane of the foliation, plus  68  recrystallization of primary minerals (quartz and feldspar) and secondary alteration minerals (quartz, biotite, magnetite, and sulphides). Folded dikelets have axial planes (AP) parallel to SP. Gradational boundaries between zones of gneissic banding and variably deformed KGd strongly suggest KGd is the protolith of gneissic zones.  69  2.4.3  Sulphide Deformation Fabrics  Bornite and chalcopyrite are present as disseminated grains up to several millimeters in diameter, as thin discontinuous veinlets and/or interconnected elongate blebs, and as massive “web” or “net” textures enveloping other minerals. Deformation has variably overprinted sulphides bearing each of these textures. Chalcopyrite and bornite appear to be ubiquitously deformed at the microscale, with sulphides sharing cuspate grain boundaries with internally deformed quartz or feldspar (Figure 21). Ductile deformation and potential re-equilibration and thermal annealing of sulphides, possible at temperatures as low as 100 °C (Brett, 1964; Durazzo and Taylor, 1982), precludes sulphide textures from being useful as indicator of original mineralisation habit. At hand-scale “web” textures are associated with mineralization in strongly folded rocks (Figure 22A and B), especially within fold hinges. The geometry of cusp structures at hand specimen and larger appears may be approaching boudin necks or mullions, interpreted to form under high-grade metamorphic conditions where sulphides are rheologically much weaker compared to their wall rocks, i.e., formed during layer-parallel shortening where relatively less competent sulphide layer deform into cusps protruding into more competent wall-rocks (e.g., Sokoutis, 1987; Sokoutis, 1990; Talbot and Sokoutis, 1992). Sulphide mullions are common within deformed sulphide deposits, e.g., the Selebi Pikwe Cu-Ni deposit in Botswana (Osterman and Hutchinson, 1994), the Trojan Ni deposit in Zimbabwe (Maiden et al., 1986), the Matchless Cu deposit in South-West Africa (Maiden et al., 1986), and the Broken Hill Ag-Pb-Zn deposit in Australia (Maiden et al., 1986).  70  Figure 21: Photomicrograph showing microtextures of typical Cu-sulphide deformation at Minto. Bornite with chalcopyrite exsolution lamellae. Cuspate contact with silicates are interpreted as reflecting the deformation of a silicate-sulphide mass where sulphides are less competent than the silicate, producing cuspate shapes. Chalcopyrite exsolution lamellae indicate chemical re-equilibration after bornite precipitation, and the sharp, tapered, undeformed texture indicates formation after ductile deformation (Brett, 1964; Durazzo and Taylor, 1982).  71  Figure 22: Photomicrograph showing macroscopic deformation of Cu-sulphides at Minto. A. Cusulphides are most associated with biotite foliation or quartz alteration, and these regions are observed to deform more readily than surrounding feldspar-rich rocks. Deforming sulphide-rich zones tend to form cusp and lobate structures, essentially analogous to the texture shown in Figure 21. Sulphides within folded deformation zones appear to be enriched within hinges. Hand specimen taken from the Minto pit at 730 m elevation. B. Web or net textured chalcopyrite-bornite mineralization is typical of high grade Cu-sulphide zones at Minto. Remobilisation of sulphides into low strain areas of fold hinges may be responsible for upgrading hydrothermal ore grades. Outcrop is located in the west of the Minto pit at 730 m elevation.  72  2.4.4  Foliation and Shear Zone Geometry  There is limited outcrop available outside of the Minto pit and much of that is of massive rock due to preferential weathering of foliated rock. Extensive diamond drilling has been performed across the property, but most of it is not oriented. Such core is useful for assessing progressive foliation development but provides limited information on foliation orientation, although the vertical orientation of most of the holes does help to constrain possible foliation orientation. To gain an understanding of the mesoscopic to macroscopic geometry of foliated rocks, accessible pit faces and all natural surface exposure were mapped and structurally assessed. Six oriented drill holes across the property provided some 3D constraints on foliation geometry in the subsurface. SP measured from regional outcrop, the open pit, and oriented drill holes indicates that foliation throughout the Minto property dips predominately northeast or southwest, with dip varying from shallow to steep orientation (Figure 23A). However, the orientation of SP is most likely to be subhorizontal (Figure 23B). SP is localized into shear zones ranging in scale from millimetres to metres, and with structural contacts grading into massive rock over distances from millimetres to metres (Figure 24A, B, C, D, and E). These structural contacts between massive and deformed rocks are interpreted to arise from partitioned deformation. Structural contacts are through evidence of strain related recrystallization, e.g., abrupt grain size reductions of quartz, plagioclase, K-feldspar, epidote, and biotite (Tullis and Yund, 1985; Ree et al., 2005), tapered deformation twins in plagioclase, myrmekite development in K-feldspar, and lobate to amoeboid quartz and feldspar inter-grain boundaries (Poirier and Guillopé, 1979; Urai et al., 1986).  73  Figure 23: Stereonets depicting SP foliations measured at Minto. A. Equal area stereonet showing the distribution of SP measured during study of the Minto deposit. Measurements from outcrop (solid dots) overlap measurements from drillcore (open dots) indicating lateral variation of SP across the deposit is approximately similar to vertical variation. B. Equal area stereonet with gridded contours representing density of poles to SP foliation. The dominant cluster of poles in each diagram occurs near the center, representing the high prevalence of shallow foliation. Lesser clusters occur near stereonet margins, representing areas of steeply dipping SP.  74  75  Figure 24: Photomicrographs showing examples of structural contacts in KGd, where fine grained disseminated chalcopyrite is present within deformation zones but not incipiently deformed wallrock. A. Gradational contact showing progressive deformation increasing into shear zone, downhole. Shear zone is metres thick and bounded above and below by massive KGd. B. Sharply bound shear zone at the scale of centimetres crosscutting KGd. Quartz and plagioclase are nearly completely recrystallized, while Kfeldspar remains as augens. C. Centimetre scale deformation zone crosscutting massive KGd. D. Millimetre scale shear zone crosscutting large block of KGd.  76  Core-and-mantle textures of feldspar cores mantled by fine to medium recrystallized quartz are also common at massive-deformed rock contacts, suggesting ongoing grain size reduction played a role in development of SP foliation (White, 1975; Lister and Price, 1978; Tullis and Yund, 1985). At the scale of millimetres to tens of centimetres, these contacts are generally cuspate or penetrative at the expense of massive rocks. In many cases the contact between massive and deformed rocks represents a real strain gradient where deformation has affected a single protolith. However, it is not always possible to discern crosscutting shear zones from granitoid emplaced along pre-existing foliation (as shown in Figure 8C), especially when continued deformation overprints igneous contacts (Figure 25). Recognizing igneous contacts at Minto can be difficult because of ductile deformation fabrics are developed to some extent in all granitoids. A clear example of an igneous relationship occurs when massive intrusions cut pre-exiting foliations at high angles, or enclaves of deformed rock occur (Figure 25) in later intrusions. These relationships are observed to be overprinted by macroscopic strain, e.g., SP foliation, a clear case of deformation overprinting igneous contacts. In situations where magma was emplaced parallel to shear zones, continued deformation will have made it near impossible to recognize the primary intrusive contact. Continued deformation after the development of massive-deformed contacts is also interpreted based on the common cuspate geometry between deformed and massive granitoids at Minto at the expense of massive rocks, i.e., piercement of deformed rock into massive rock. This mullion type geometry is especially developed where secondary quartz, biotite, and/or sulphide alteration is strongest.  77  Figure 25: Photo showing SP fabric developed in a stoped enclave of deformed and magnetite altered KGd. SP has also developed separately in the younger surrounding KGd, suggesting continuous deformation affecting volumes of magma solidifying at different times, perhaps representing more than one phase of magma emplacement.  78  These regions are generally the most deformed, next to regions with strongly developed planar fabrics. Cuspate or mullion geometry has been interpreted to arise where a lessrheologically competent rock deforms more readily than its adjacent rock unit (Sokoutis, 1987; Talbot, 1982), and is a feature inherent in metamorphosed sulphide deposits (e.g., Trojan nickel deposit, Matchless copper deposit, and Broken Hill silver-lead-zinc deposit; Maiden et al., 1986; Talbot and Sokoutis, 1992). The variation of SP orientation at Minto has been observed predominately in unoriented vertical drillholes, e.g., as shown in Figure 26. The typical observed pattern is of alternating intervals of massive and variably deformed granitoids. The orientation of SP within deformed intervals is most commonly consistent throughout the interval, approximately parallel to upper and lower contacts with massive rocks. Less common are instances where SP is truncated at massive contacts, where SP changes orientation gradually or abruptly within a deformed interval, or where SP abruptly changes orientation at contacts. There are several possible geometric interpretations to explain the varying orientation of SP and the alternating intervals of massive and deformed rock observed in drill core. These explanations are based on observation of episodic igneous activity and ongoing ductile deformation, namely that the observed foliation orientations in drillholes can be explained using mostly structural or mostly igneous processes, although the true nature of the geometry is likely related to interplay between both end members (Figure 27). Foliation measurements from oriented drillholes and exposure of shear zones in the open pit (Figure 28) support a hypothesis of mainly structural creation, as per Figure 27D. The common metre to tens of metres long intervals of shallowly oriented SP foliation in drillcore are interpreted as thick, laterally continuous shear zones, as shown in Figure 29A and B.  79  80  Figure 26: Downhole variation of SP in unoriented vertical drillholes. Foliation angle is given by α angles, the angle between the core axis and the apex of foliation ellipses in core. Note that in vertical drillcore, foliation approaches horizontal as alpha approaches 90 degrees. A. Length of drill core displaying the typical alternating vertical pattern of deformed and undeformed granitoid. Foliation in vertical drill core most commonly had α oriented ~45 to 90 degrees. Foliation angles swinging through the horizontal may represent hinge zones. Foliation is poorly defined within these features and generally not possible to measure. These foliation transitions were noted most commonly in the midst of shear zones. B. Length of drill core showing short fold limb. In general, foliation transitions from sub-horizontal to sub-vertical orientation occur over several centimetres, with sub-vertical sections being tens of centimetres to metres in length. These hinge zones were noted most commonly near shear zone contacts.  81  Figure 27: Schematic diagrams illustrating possible interpretations of geometry from SP foliation observed in unoriented drillcore. A. Deformed rocks are rafts stoped into later granitoid intrusions, as per Tafti (2005). Foliation orientation would mainly be a product of raft reorientation into the younger magma intrusions. B. Deformation has been partitioned into a block of granitoids as shear zones, with continued deformation accommodated mainly by already deformed and altered rock. Steeply oriented foliation could be a product of mullion development. In this case, accommodated deformation in massive rocks could be evidenced by the narrow, spaced cross-cutting shear zones observed in outcrop. C. Foliation has been partitioned into a granitoid block as anastomosing shear zones with varying SP orientation due to shear zone development around more cohesive blocks of granitoid. D. Deformation has been partitioned into a granitoid block as parallel shear zones, with changes in foliation orientation due to later folding of the shear zones.  82  83  Figure 28: Orthophoto of the Minto mine showing the locations of logged diamond drill holes, figures with pit photographs and structural data, and cross sections.  84  85  Figure 29: Examples of shear zones in the Minto open pit. A. & B. Panoramic photo and schematic diagram of foliation, contacts, and faults in laterally continuous shear zones. The west edge of the deformation zone is terminated by a younger brittle fault, the eastern edge is obscured by strong surficial weathering, and the top of the zone is obscured by sloughed rock. The vertical thickness of the shear zone is at least 5 metres. The basal contact is abrupt, but a gradient margin of about 10 centimetres of stage 1 deformation is present within the massive block. Section is 90-212, looking north. C. & D. Mosaic photo and schematic diagram showing foliation, structural contacts, and sample locations. Four structural domains are defined by variable deformation intensity and are, from top to bottom, gneissic banding, stage 3 deformation, stage 2 deformation, and stage 1 deformation. Deformation along contacts precludes interpreting whether pre-existing igneous contacts are present, or whether deformation has been partitioned into a single rock mass. U-Pb analyses using a SHRIMP from zircons representing each of the four structural domains indicate all rocks are similar in age, approximately 197.0 Ma – 197.8 Ma. Section is 90-210, looking north. E. & F. Panoramic photo and schematic diagram showing foliation and structural contacts. This shear zone represents interpreted asymmetric folding of short steep limbs and long shallow limbs. Section is oriented 90-155, looking west.  86  Alternating zones of variably strained KGd in drillcore, with or without foliation variation, are interpreted as separated shear zones of varying width, pictured in Figure 29C and D. Intervals of drillcore containing vertical successions in which foliation abruptly swings from horizontal orientation to relatively shorter intervals of steeply oriented foliation are interpreted as intersections with fold hinges, as exhibited in Figure 29E. and F. The interpretation of folded shear zones with asymmetric geometry is roughly consistent with separate interpretations from stereonet plots of regionally measured SP (Figure 30). A complication of this interpretation comes from folding internal to shear zones, especially where shear zone boundaries are not exposed and thus not available for comparison. Internal folding of SP within shear zones is common, and fold geometries vary (Figure 31A, B, and C.). The orientation of folds measured at the Minto property mainly dip northeast to southwest with varying steepness (Figure 31D.) and with hinges plunging shallowly northwest to southeast (Figure 31E.). It is not clear based on the data within this thesis what relationship various folds have with the intensity of mineralization, although there are coincidences between the strike of axial planes of folded shear zones (e.g., those shown in Figure 32) and the trend of high grade mineralisation (Figure 33 and Figure 34).  87  88  89  Figure 30: Stereonets of SP measured from regions across the Minto deposit. Foliation is consistent across the deposit in that orientations are most commonly subhorizontal, and that foliation varies in dip essentially from northeast to southwest. Stereonets C., G., and K. exhibit bimodal clustering of poles to foliation, possibly indicative of asymmetric folding and consistent with folds with short-limb long-limb asymmetric geometry, as observed in drillcore and outcrop.  90  91  Figure 31: Variation of SP folding observed within shear zones in the Minto open pit. AT = axial trace. A. Asymmetric folds with moderately dipping axial plane possibly overprinted by open folding with more steeply dipping axial plane. Location shown on Figure 28. B. Folded and boudinaged interval of medium grained tonalite within strongly mineralized pit outcrop. Igneous textures within tonalite are preserved, a possible indication that the unit was still molten during deformation. Axial plane of fold dips 60 degrees and strikes ~ 330 degrees to the northwest Location shown on Figure 28. Rock contains greater than 3% Cu as chalcopyrite-bornite. C. Asymmetric folds with angular hinges in moderately deformed KGd. Axial plane of fold dips 70 degrees and strikes ~330 degrees to the northwest. Sub-metre intervals of gneissic banding are present and grade into stage 3 deformed KGd with abundant folded pegmatite dikelets (red). Rock contains greater than 3% Cu as chalcopyrite-bornite. Location shown on Figure 28 D. Equal area stereonet of poles to fold axial planes measured across the Minto deposit in oriented drillcore and outcrop. Dip of axial planes varies from shallow to steep, with strike most commonly northwest or southeast. E. Equal area stereonet of fold axial planes, plus hinge line plunges. Hinges typically plunge shallowly to the southeast or northwest.  92  93  Figure 32: Graphical log of diamond drill hole 06SWC078 showing a correlation between potassic alteration, sulphide type, and ore grade. Additional graphical logs and locations of drillhoels are given in Appendix F . Intensity of potassic alteration is represented by magnetite content (magnetic susceptibility as a proxy), plus biotite content (visual estimation of weak/moderate/strong). Relative deformation intensity (DI) is indicated by the degree on recrystallization of quartz/plagioclase/K-feldspar as described earlier in the text. Deformation intensity, presence of garnet or hornblende, quartzofeldspathic dikelets, silicification, or gypsum are not obviously spatially correlated to mineralization. Propylitic alteration and potentially associated epidote veining overprint massive and deformed/mineralized zones. Alpha = angle between core axis and SP foliation, Sil’n = silicification, Kfs = K-feldspar.  94  95  Figure 33: Map of the Minto open pit summarising SP foliation geometry. Main trend of steeply dipping foliation and axial planes of folded SP is approximately 330 degrees. There is also a second foliation trend at approximately 200 degrees. Note that the 300 degree trend approximately parallels the high grade core of the open pit. Property foliation, SP, measurements have been binned into groups representing shallow, moderate, and steep foliation: 0- 30 degrees, 30- 60 degrees, and 60-90 degrees, respectively. Copper grade thickness is calculated from drill hole assays as the sum of (copper grade) x (grade intercept length), and is contoured to show regions of the most mineralisation, inclusive of rock removed during mining. The northeast trend of grade-thickness shown is interpreted as correlated to the similar strike of steep foliation. The trend of grade-thickness also corresponds to Capstone’s block model of mineralisation at 730m elevation, i.e., within the main mineralised shear zone targeted in the Minto open pit (Capstone Geologists, pers. comm.). Trends of grade thickness are thus considered an approximation for zones of high mineralisation.  96  97  Figure 34: Steep foliation and Cu-grade thickness from the Minto deposit. Steeply dipping foliation dominantly trends northwest-southeast represents relatively narrow zones of overprinting deformation where SP has been rotated to a steeper dip. The dip direction of shallow to moderate foliation is varied and no major trends are observed. A (copper-grade) x (grade intercept thickness) contour map is given to show the main mineralization trend of the deposit. This corridor of higher grade thickness values is developed subparallel to the northwest-southeast enveloping trend of steeply dipping SP. Shallow foliations are removed for clarity.  98  2.4.5  Late Brittle Deformation  Brittle fractures are observed throughout the Minto pluton at scales ranging from microscopic to regional. Microfractures locally crosscut igneous contacts, and magmatic and solid state foliation. Propylitic alteration is typically controlled by brittle fractures that also crosscut igneous and structural contacts. More relevant to exploration are late brittle faults that dissect mineralisation zones. These faults mainly trend approximately east-west, with the largest being the DEF fault (Figure 3).  99  2.5  Geochronology  There have been four previous studies to constrain the timing of intrusion for granodiorites at the Minto deposit. Pearson (1977) reported two K-Ar biotite ages of 180 (+/- 9) Ma and 177 (+/- 9) Ma for samples of granodiorite and altered granodiorite (“biotite gneiss”). Tempelman-Kluit et al. (1980) reported a  206  Pb/238U age of 191 (+/- 3) Ma and a  207  Pb/235U  age of 192 (+/- 3) Ma for a hornblende-bearing granodiorite from the Minto discovery outcrop and a K-Ar biotite age of 174 (+/- 6 Ma) for a foliated granodiorite. More recent dating by Mortensen and Tafti (2002) and Tafti (2005) worked to refine intrusion ages using U-Pb Isotope Dilution-Thermal Ionization Mass Spectrometry techniques. Most samples of granodiorite and deformed/foliated granitoid yielded ages that were variably discordant, reflecting multiple stages of zircon inheritance and post-crystallization lead-loss (Tafti, 2005). No ages for undeformed/altered granitoids are reported; however a zircon age of 197.2 (+/-) 2.1 Ma is assigned to one sample of “garnet-bearing mineralized orthogneiss” (Tafti, 2005), interpreted in this thesis as a strongly deformed granodiorite with quartzofeldspathic banding and Cu-sulphide alteration. Another age of 197.8 +/- 2.5 Ma was assigned to a sample of “siliceous ore” (Tafti, 2005), interpreted here as a strongly deformed quartz + Cu-sulphide occurring in deformed and altered granodiorite. Both of these samples were taken from drill core around the main Minto deposit. U-Pb titanite age dates for a suite of variably deformed and altered Minto granodiorites were reported by Tafti (2005) and range between 194.0 Ma to 185.1 Ma, consistently younger than U-Pb zircon ages. This effect may be attributed to thermal resetting (Tafti, 2005) or reactivity of titanite in high temperature environments with Ti or Ca bearing fluids (Scott and St-Onge, 1995).  100  This study constrains the age of pluton emplacement, and the age of mineralisation, for the Minto Pluton using U-Pb geochronology on zircon and Re-Os geochronology on molybdenite. In situ U-Pb dating was done using the Sensitive High Resolution Ion Microprobe (SHRIMP II) at the Geological Survey of Canada Geochronology Laboratories in Ottawa, Canada. The SHRIMP II was chosen to limit inheritance issues and lead-loss along internal fractures documented in earlier studies where whole grain digestion of zircons was used. Contact relationships between granodiorite phases at Minto suggest a history of multiple magma batches, overprinted by partitioned deformation and hydrothermal alteration. Samples for geochronology were chosen from the open pit and drill core to represent igneous contacts and partitioned deformation. 2.5.1 2.5.1.1  U-Pb SHRIMP Geochronology Samples  Two suites of granodiorite samples were collected to constrain intrusion ages and to complement cross-cutting relationships that constrain the relative timing of pluton emplacement, deformation, and alteration/mineralisation (Appendix 4). The first suite of two samples comprises a moderately altered granodiorite enclave within a fresh granodiorite host (Figure 6B). Sample S08-01-01 is an enclave of altered granodiorite within a body of unaltered granodioritic host represented by sample S09-13-03A. Samples were collected from a well-exposed road cut along the Minto access road near the Minto Dam. KGd exposure in the sample area consists mainly of typical Minto granodiorites, fault bounded at the east of the outcrop with weakly propylitically altered granodiorites. Host KGd in this area is commonly includes crowded K-feldspar porphyry, enclaves of altered KGd,  101  and mafic magmatic enclaves. This suite was samples to examine the timing relationship between batches of KGd. The second suite of four samples were collected from a sequence of vertically stacked deformed and massive granodiorites within the hangingwall of the DEF fault in the Minto pit (Figure 28C and D). This interval is interpreted to represent shear zones cross-cutting a single, relatively undeformed, phase of intrusion.. 2.5.1.2  Analyses  U-Pb SHRIMP II analyses were conducted at the Geological Survey of Canada (GSC) in Ottawa using analytical procedures described by Stern (1997), with standards and U-Pb calibration methods following Stern and Amelin (2003). Heavy minerals were separated from six samples using standard methods (crushing, Wilfley table, heavy liquids) and sorted according to magnetic susceptibility using a Frantz isodynamic separator. Zircons for all but sample S09-16-03C were recovered by Apatite to Zircon, Inc. Zircons separated from the six samples show signs of inheritance in backscatter and reflected light (photographs of hand specimen and micrographs of analysed grains are provided in Appendix G ). Xenocrystic cores with younger overgrowth were identified by geometrically irregular surfaces truncating internal zoning, or by observing growth zoned rims around cores that were subrounded or euhedral, unzoned, or chaotically zoned (Corfu et al., 2003). The rims of zircons were targeted in this study as a means of identifying the last phase of zircon growth, i.e., the age of host rock intrusion. Zircons were cast in 2.5 cm diameter epoxy mounts along with fragments of the GSC laboratory standard zircons (z6266, with 206  206  Pb/238U age = 559 Ma, and z8539 Temora, with  Pb/238U age 417 Ma). The mid-sections of the zircons were exposed using 9, 6, and 1 µm  102  diamond compound, and the internal features of the zircons (such as zoning, structures, alteration, etc.) were characterized in reflected light and back-scattered electron mode (BSE) utilizing a Zeiss Evo 50 scanning electron microscrope. Mount surfaces were evaporatively coated with 10 nm of high purity Au. Analyses were conducted using a  16  O- primary beam,  projected onto the zircons at 10 kV. The sputtered area used for analysis was ca. 35 µm in diameter with a beam current of ca. 15 nA. The count rates at ten masses including background were sequentially measured over 5 scans with a single electron multiplier and a pulse counting system with deadtime of 23 ns. Off-line data processing was accomplished using customized in-house software. The 1σ external errors of  206  Pb/238U ratios reported in  the data table incorporate a +/- 1.0 % error in calibrating the standard zircon (see Stern and Amelin 2003). No fractionation correction was applied to the Pb-isotope data; common Pb correction utilized the Pb composition of the surface blank (Stern, 1997). Weighted average ages are given at 95% confidence level (2σ), determined using Isoplot (Ludwig, 1998). Uranium-lead analyses are presented numerically in Table 4 and graphically on concordia plots (Figure 35). The majority of Minto zircons yielded approximately 197 Ma and 200 Ma. Zircons with  206  Pb/238U ages between  206  Pb/238U ages around 300 Ma, observed  within samples S09-13-03A, S09-16-01B, and S09-16-01D, are interpreted as inherited zircons from the Yukon Tanana Terrane, country rock to the granodiorite intrusions. Individual analyses were culled from  206  U/238Pb age calculations based on inheritance, Pb-  loss, high common Pb, analyses with %206Pb greater than 2%, anomalously high/low UO/U, or when spot locations included cracks or zircon grain boundaries (Nicole Rayner, pers. comm.).  103  Table 4: Results of U-Pb SHRIMP analyses of KGd zircons and age calculations. Calculated ages are shown graphically on concordia diagrams in Figure 35. Atomic Ratios Sample  S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A S09-13-03A  Spot  10265-33.2 10265-53.1 10265-46.1 10265-33.3 10265-94.1 10265-81.1 10265-87.1 10265-69.1 10265-11.1 10265-32.1 10265-29.1 10265-80.1 10265-18.1 10265-91.1 10265-79.1 10265-86.1 10265-63.1 10265-25.1 10265-7.1 10265-4.1 10265-24.1 10265-2.1 10265-10.1 10265-8.1 10265-15.1 10265-12.1 10265-55.1 10265-33.1 10265-85.1 10265-64.2  ppm U  536.41 256.65 767.08 438.29 552.59 836.32 586.99 654.41 529.47 389.22 722.46 404.64 589.48 612.08 751.75 473.75 658.64 405.28 652.84 708.48 941.73 300.06 787.06 690.08 511.89 513.80 466.04 173.42 340.64 139.26  Th/U Y Hf ppm ppm  0.30 0.50 0.28 0.22 0.26 0.31 0.25 0.35 0.37 0.28 0.33 0.28 0.26 0.30 0.40 0.29 0.29 0.44 0.27 0.43 0.42 0.39 0.27 0.28 0.30 0.35 0.31 0.47 0.40 0.37  549 638 1284 581 460 1427 940 1334 414 555 1017 520 882 849 1627 800 926 1085 804 908 1145 481 1172 1718 540 664 859 1448 1283 2030  12676 9668 11924 11561 12822 12261 11098 11596 10861 11474 10952 10777 12209 11553 11924 11586 11424 10327 12328 11349 11779 10868 12417 8981 13172 11766 11469 9849 10224 9593  ppm 206*  13.94 6.69 20.16 11.53 14.58 22.14 15.67 17.48 14.16 10.45 19.47 10.96 15.98 16.59 20.40 12.91 18.04 11.10 17.90 19.52 26.13 8.43 22.33 20.09 15.53 17.08 18.21 7.23 14.87 6.21  %f206207 204Pb /206Pb  1.01 1.87 0.38 1.30 0.93 0.37 1.65 1.54 0.24 0.98 0.44 1.40 0.86 0.29 0.71 0.25 0.82 1.61 0.29 0.47 0.45 0.61 0.20 0.00 0.00 0.19 1.69 2.43 1.90 3.29  5.8E-04 1.1E-03 2.2E-04 7.5E-04 5.3E-04 2.2E-04 9.5E-04 8.9E-04 1.4E-04 5.6E-04 2.5E-04 8.1E-04 5.0E-04 1.7E-04 4.1E-04 1.4E-04 4.7E-04 9.3E-04 1.7E-04 2.7E-04 2.6E-04 3.5E-04 1.2E-04 1.0E-32 1.0E-32 1.1E-04 9.7E-04 1.4E-03 1.1E-03 1.9E-03  ±%  40 58 19 26 31 85 31 28 29 33 127 33 151 34 56 54 20 26 20 24 101 48 106 100 100 24 31 34 28 40  Uncorrected 208Pb ±% ±% /206Pb 238U / 206Pb 0.118 0.209 0.082 0.087 0.048 0.091 0.085 0.120 0.121 0.102 0.107 0.112 0.082 0.115 0.110 0.109 0.087 0.136 0.084 0.137 0.134 0.123 0.095 0.093 0.108 0.098 0.106 0.169 0.129 0.179  10.1 10.0 9.4 12.4 21.3 8.5 11.1 9.3 7.7 14.4 7.7 11.3 8.6 9.0 9.0 10.5 11.4 8.2 8.8 7.6 7.2 10.4 6.9 8.9 9.1 8.0 9.3 11.1 9.3 11.4  32.73 32.36 32.56 32.24 32.26 32.32 31.65 31.65 32.03 31.67 31.74 31.26 31.42 31.59 31.43 31.44 31.10 30.85 31.23 31.03 30.82 30.38 30.21 29.50 28.32 25.79 21.61 20.09 19.30 18.62  1.34 1.64 1.30 1.35 1.49 1.30 1.33 1.34 1.30 1.66 1.44 1.33 1.56 1.61 1.33 1.69 1.99 1.35 1.49 1.61 1.30 1.50 1.30 1.33 1.57 1.35 1.37 1.78 1.50 1.68  Ages (Ma)  204 Corrected (1) ±% 207Pb* ±% ±% 207Pb /235U 206Pb* /206Pb /238U 0.050 0.063 0.051 0.066 0.055 0.051 0.053 0.057 0.052 0.050 0.052 0.053 0.053 0.054 0.049 0.053 0.051 0.054 0.050 0.053 0.049 0.053 0.050 0.052 0.053 0.053 0.058 0.070 0.055 0.084  3.3 8.8 2.6 3.1 3.2 2.5 3.1 3.0 2.6 4.6 2.5 3.6 2.4 2.9 3.0 3.3 3.2 2.9 2.5 2.7 3.3 3.5 2.1 2.6 2.9 2.4 2.8 3.8 3.2 6.9  0.171 0.197 0.201 0.233 0.199 0.203 0.167 0.188 0.216 0.178 0.209 0.179 0.197 0.223 0.188 0.222 0.196 0.179 0.208 0.216 0.200 0.214 0.219 0.245 0.258 0.275 0.271 0.329 0.274 0.402  9.46 23.18 3.33 6.66 6.64 6.38 12.34 9.50 3.22 8.92 10.31 10.96 24.91 3.85 8.74 4.48 5.28 9.94 3.20 3.88 9.51 6.74 4.54 2.94 3.28 2.90 11.31 15.61 12.60 22.81  0.0302 0.0303 0.0306 0.0306 0.0307 0.0308 0.0311 0.0311 0.0311 0.0313 0.0314 0.0315 0.0316 0.0316 0.0316 0.0317 0.0319 0.0319 0.0319 0.0321 0.0323 0.0327 0.0330 0.0339 0.0353 0.0387 0.0455 0.0486 0.0508 0.0519  1.40 1.98 1.30 1.40 1.52 1.34 1.43 1.41 1.30 1.69 1.54 1.41 2.04 1.61 1.39 1.70 2.00 1.41 1.49 1.61 1.38 1.53 1.32 1.33 1.57 1.35 1.47 1.96 1.59 2.15  err corr  0.148 0.085 0.392 0.210 0.229 0.210 0.116 0.148 0.404 0.189 0.150 0.129 0.082 0.418 0.158 0.379 0.378 0.142 0.466 0.416 0.146 0.227 0.290 0.450 0.478 0.465 0.130 0.126 0.126 0.094  204 206Pb/238U Calibration 206Pb* Error % /238U Age 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27  192.1 192.6 194.3 194.4 195.0 195.7 197.3 197.5 197.7 198.5 199.1 200.2 200.3 200.3 200.5 201.4 202.4 202.4 202.6 203.5 204.9 207.5 209.5 214.9 223.7 244.7 286.8 305.7 319.6 326.5  207 206Pb* /238U Age 3 4 2 3 3 3 3 3 3 3 3 3 4 3 3 3 4 3 3 3 3 3 3 3 3 3 4 6 5 7  104  194.1 193.2 194.8 193.2 195.7 196.2 199.8 198.9 197.6 200.5 199.5 202.3 201.4 200.0 202.1 201.2 203.7 204.7 203.3 203.8 206.2 208.2 210.0 214.4 223.1 244.6 289.7 306.9 324.7 325.3  3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 3 3 3 3 3 3 3 3 3 4 5 5 6  Atomic Ratios Sample  S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01 S08-01-01  Spot  10266-22.1 10266-53.1 10266-81.1 10266-1.1 10266-23.1 10266-39.1 10266-42.1 10266-8.1 10266-37.1 10266-43.1 10266-18.1 10266-41.1 10266-73.1 10266-33.1 10266-2.1 10266-59.1 10266-29.1 10266-17.1 10266-45.1 10266-82.1 10266-66.1 10266-71.1 10266-54.1 10266-49.1 10266-80.1 10266-68.1 10266-31.1 10266-63.1 10266-76.1 10266-30.1 10266-25.1 10266-55.1 10266-34.1 10266-70.1 10266-46.1 10266-74.1 10266-75.1 10266-69.1  ppmU  139.22 255.45 184.87 399.05 281.14 218.71 185.70 310.04 329.12 352.35 589.15 296.33 347.49 158.15 597.20 567.21 298.12 336.42 370.25 255.61 359.54 429.84 185.66 238.50 528.79 357.06 348.65 305.62 506.22 521.80 311.28 917.70 1014.23 605.83 283.49 512.70 1215.84 371.13  Th/U Y ppm  0.38 0.32 0.34 0.35 0.31 0.36 0.48 0.30 0.42 0.33 0.51 0.34 0.35 0.38 0.40 0.55 0.30 0.36 0.34 0.50 0.54 0.40 0.28 0.36 0.59 0.45 0.60 0.33 0.58 0.57 0.40 0.52 0.44 0.44 0.43 0.76 0.50 0.24  523 242 561 687 439 702 847 491 407 444 409 532 368 575 689 911 420 529 483 862 817 527 259 794 480 863 1465 434 1078 686 512 1336 1179 920 690 1189 1044 394  Hf ppm  10442 10513 10239 10325 10092 10260 9589 10073 10361 10256 10736 10123 10510 10369 10243 10541 10224 10312 10227 9444 10440 10390 10400 10142 10439 10444 10545 10160 10137 10503 10421 10261 11181 10412 10580 10257 10817 9758  ppm 206*  3.55 6.57 4.79 10.34 7.28 5.69 4.84 8.13 8.67 9.33 15.60 7.87 9.27 4.23 15.98 15.19 7.99 9.02 9.95 6.88 9.72 11.70 5.06 6.50 14.42 9.74 9.51 8.36 13.85 14.29 8.53 25.17 27.90 16.67 7.85 14.20 33.71 10.40  %f206207 204Pb /206Pb  2.40 2.99 1.98 0.86 1.14 1.94 4.35 1.21 0.37 1.12 0.34 0.55 0.14 1.31 0.17 0.92 0.70 0.17 0.23 0.66 0.46 1.30 -0.43 0.21 0.85 0.42 0.78 -0.46 0.72 0.56 0.32 0.23 1.48 0.00 0.73 0.20 0.97 3.52  1.4E-03 1.7E-03 1.1E-03 5.0E-04 6.5E-04 1.1E-03 2.5E-03 7.0E-04 2.1E-04 6.4E-04 1.9E-04 3.2E-04 8.1E-05 7.5E-04 9.6E-05 5.3E-04 4.0E-04 9.9E-05 1.3E-04 3.8E-04 2.6E-04 7.5E-04 -2.5E-04 1.2E-04 4.9E-04 2.4E-04 4.5E-04 -2.7E-04 4.2E-04 3.2E-04 1.8E-04 1.3E-04 8.5E-04 1.0E-32 4.2E-04 1.2E-04 5.6E-04 2.0E-03  ±%  33 26 31 114 52 33 23 64 235 30 39 48 429 36 58 29 59 73 145 200 18 28 198 16 34 37 161 2 64 65 34 134 21 100 32 73 22 25  Uncorrected 208Pb ±% /206Pb 238U/ 206Pb 0.138 0.123 0.121 0.117 0.152 0.164 0.205 0.089 0.152 0.087 0.180 0.132 0.134 0.111 0.141 0.185 0.122 0.114 0.106 0.189 0.211 0.158 0.082 0.119 0.192 0.162 0.190 0.112 0.211 0.189 0.139 0.180 0.155 0.129 0.173 0.251 0.154 0.117  13.2 10.8 12.3 8.6 8.7 9.7 9.4 11.6 8.1 10.8 5.6 9.4 8.9 14.5 6.2 5.8 9.6 9.1 13.6 8.5 6.9 7.0 15.3 11.3 6.2 7.5 7.1 10.5 5.5 5.9 8.6 8.9 4.8 9.9 8.2 4.9 4.2 10.6  32.86 32.41 32.53 32.87 32.78 32.38 31.53 32.38 32.50 32.09 32.34 32.18 32.15 31.71 32.05 31.79 31.84 31.98 31.89 31.68 31.61 31.15 31.67 31.46 31.24 31.37 31.25 31.54 31.17 31.19 31.23 31.24 30.77 31.22 30.81 30.95 30.68 29.58  ±% 207Pb /206Pb 1.12 1.12 1.10 1.10 1.06 1.08 1.10 1.67 1.12 1.06 1.14 1.06 1.24 1.11 1.14 1.19 1.06 1.05 1.12 1.07 1.21 1.05 1.10 1.12 1.04 1.05 1.20 1.07 1.15 1.04 1.06 1.02 1.03 1.08 1.06 1.11 1.10 1.27  0.057 0.065 0.059 0.054 0.054 0.070 0.060 0.061 0.057 0.057 0.052 0.059 0.055 0.055 0.053 0.052 0.052 0.051 0.056 0.055 0.054 0.056 0.059 0.057 0.053 0.053 0.057 0.054 0.055 0.051 0.056 0.053 0.062 0.051 0.054 0.051 0.052 0.057  Ages (Ma)  ±% 207Pb* ±% /235U  4.6 3.3 3.9 2.8 4.2 7.8 3.9 3.2 3.0 3.0 2.3 3.2 3.1 4.5 2.3 2.5 3.3 3.0 2.8 3.6 3.0 2.6 4.0 3.6 3.2 2.9 2.9 3.4 2.4 2.5 3.0 1.8 1.7 2.2 5.0 2.4 1.6 3.4  0.149 0.164 0.176 0.196 0.183 0.226 0.093 0.216 0.228 0.203 0.211 0.230 0.229 0.188 0.222 0.190 0.199 0.213 0.233 0.212 0.218 0.196 0.272 0.243 0.201 0.217 0.221 0.256 0.214 0.201 0.235 0.224 0.217 0.225 0.214 0.221 0.197 0.121  204 Corrected (1) ±% 206Pb* /238U  20.58 18.13 13.69 18.13 12.66 14.54 42.43 13.66 13.85 7.10 3.51 5.55 10.11 10.92 3.04 6.03 8.57 3.94 6.01 23.36 3.77 7.84 12.06 3.89 6.67 4.27 21.53 3.30 8.65 7.43 3.78 5.60 6.01 2.45 7.12 3.75 4.72 30.09  0.0297 0.0299 0.0301 0.0302 0.0302 0.0303 0.0303 0.0305 0.0307 0.0308 0.0308 0.0309 0.0311 0.0311 0.0312 0.0312 0.0312 0.0312 0.0313 0.0314 0.0315 0.0317 0.0317 0.0317 0.0317 0.0317 0.0317 0.0319 0.0319 0.0319 0.0319 0.0319 0.0320 0.0320 0.0322 0.0322 0.0323 0.0326  1.38 1.38 1.26 1.48 1.22 1.26 1.51 1.85 1.41 1.11 1.14 1.09 1.38 1.21 1.14 1.22 1.14 1.06 1.17 1.71 1.22 1.11 1.39 1.12 1.08 1.06 1.75 1.07 1.24 1.10 1.06 1.07 1.08 1.08 1.09 1.12 1.12 1.56  err corr  0.067 0.076 0.092 0.082 0.096 0.087 0.036 0.135 0.102 0.156 0.326 0.197 0.137 0.111 0.377 0.202 0.133 0.269 0.194 0.073 0.323 0.142 0.115 0.287 0.163 0.249 0.081 0.323 0.143 0.148 0.281 0.191 0.179 0.443 0.153 0.298 0.237 0.052  204 206Pb/238U Calibration 206Pb* Error % /238U Age 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00  188.7 190.1 191.4 191.5 191.6 192.3 192.6 193.8 194.7 195.6 195.7 196.2 197.2 197.6 197.7 197.9 198.0 198.2 198.6 199.0 199.9 201.1 201.3 201.3 201.4 201.5 201.5 202.1 202.1 202.3 202.5 202.6 203.2 203.3 204.4 204.6 204.8 206.9  207 206Pb* /238U Age 3 3 2 3 2 2 3 4 3 2 2 2 3 2 2 2 2 2 2 3 2 2 3 2 2 2 3 2 2 2 2 2 2 2 2 2 2 3  191.7 192.3 193.1 192.2 192.9 191.3 198.9 193.5 193.7 196.2 195.8 195.3 196.4 199.0 197.4 199.2 198.9 198.3 197.7 199.3 199.9 202.3 198.4 200.0 202.4 201.6 201.4 200.2 202.5 203.4 201.8 202.5 203.4 203.1 204.9 204.7 206.2 212.5  105  2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3  Atomic Ratios Sample  Spot  ppm U  Th / Y Hf U ppm ppm  ppm 206*  S09-16-01A 10267-21.1 215.97 0.42 488 10830 4.84 S09-16-01A 10267-15.1 231.20 0.34 364 10555 5.71 S09-16-01A 10267-13.1 185.13 0.48 529 10423 4.66 S09-16-01A 10267-52.1 230.08 0.31 445 10531 5.84 S09-16-01A 10267-14.1 122.24 0.34 403 10806 3.13 S09-16-01A 10267-62.1 235.56 0.42 717 10354 6.08 S09-16-01A 10267-82.1 362.98 0.50 475 10774 9.39 S09-16-01A 10267-80.1 468.02 0.56 1094 10420 12.17 S09-16-01A 10267-33.1 368.37 0.53 900 10343 9.58 S09-16-01A 10267-70.1 360.48 0.36 484 10005 9.39 S09-16-01A 10267-58.1 184.88 0.34 542 10464 4.86 S09-16-01A 10267-57.1 357.67 0.44 422 10171 9.41 S09-16-01A 10267-1.1_A 233.75 0.54 495 10425 6.16 S09-16-01A 10267-29.1 180.13 0.49 537 9650 4.76 S09-16-01A 10267-77.1 164.09 0.33 521 10794 4.34 S09-16-01A 10267-74.1 219.82 0.38 687 10687 5.83 S09-16-01A 10267-81.1 350.34 0.53 729 10907 9.30 S09-16-01A 10267-16.1 281.00 0.55 760 10696 7.48 S09-16-01A 10267-18.1 479.13 0.49 370 10465 12.76 S09-16-01A 10267-111.1 152.55 0.42 477 9797 4.09 S09-16-01A 10267-65.1 234.98 0.44 760 10383 6.31 S09-16-01A 10267-91.1 474.44 0.37 643 9816 12.75 S09-16-01A 10267-71.1 367.32 0.43 494 10510 9.88 S09-16-01A 10267-11.1 438.51 0.55 840 10725 11.80 S09-16-01A 10267-69.1 362.14 0.57 903 10575 9.75 S09-16-01A 10267-10.1 317.85 0.39 946 10488 8.56 S09-16-01A 10267-88.1 274.75 0.33 219 10879 7.40 S09-16-01A 10267-1.1 364.34 0.49 730 10391 9.83 S09-16-01A 10267-9.1 572.79 0.66 613 10444 15.46 S09-16-01A 10267-110.1 224.37 0.39 479 10260 6.08 S09-16-01A 10267-31.1 441.85 0.58 843 10141 11.99 S09-16-01A 10267-87.1 176.98 0.40 459 11067 4.81 S09-16-01A 10267-37.1 413.10 0.47 818 10084 11.24 S09-16-01A 10267-25.1 319.65 0.51 579 10670 8.70 S09-16-01A 10267-85.1 399.51 0.44 514 10400 10.88 S09-16-01A 10267-72.1 254.16 0.39 296 10527 6.96 S09-16-01A 10267-86.1 466.26 0.54 325 10531 12.92  % f206207  4.85 2.22 1.55 2.86 2.56 1.19 1.53 0.34 1.60 0.24 3.21 1.42 1.16 2.24 1.08 0.69 0.86 1.39 0.34 2.05 3.08 1.50 1.71 1.15 0.32 0.00 0.59 1.67 0.85 0.00 3.98 1.32 2.93 1.92 0.96 0.97 0.65  204Pb /206Pb  2.8E-03 1.3E-03 8.9E-04 1.7E-03 1.5E-03 6.8E-04 8.9E-04 2.0E-04 9.2E-04 1.4E-04 1.9E-03 8.2E-04 6.7E-04 1.3E-03 6.2E-04 4.0E-04 5.0E-04 8.0E-04 1.9E-04 1.2E-03 1.8E-03 8.6E-04 9.8E-04 6.6E-04 1.8E-04 1.0E-32 3.4E-04 9.6E-04 4.9E-04 1.0E-32 2.3E-03 7.6E-04 1.7E-03 1.1E-03 5.5E-04 5.6E-04 3.7E-04  ±%  27 19 103 29 24 19 21 29 35 263 32 36 24 35 63 26 39 73 32 42 29 30 34 68 36 100 33 24 25 100 20 21 30 38 45 19 35  Uncorrected 208Pb ±% ±% /206Pb 238U/ 206Pb 0.159 0.135 0.134 0.120 0.130 0.121 0.173 0.191 0.179 0.119 0.135 0.143 0.195 0.200 0.117 0.121 0.195 0.205 0.168 0.111 0.120 0.127 0.145 0.160 0.184 0.109 0.154 0.200 0.226 0.110 0.239 0.153 0.210 0.187 0.177 0.145 0.199  20.7 13.4 17.3 13.6 21.4 13.7 8.7 7.2 9.1 11.1 13.9 9.5 10.7 12.3 16.6 15.4 8.5 12.3 8.1 17.3 13.1 8.8 9.6 10.9 8.5 12.8 11.6 9.4 6.4 15.6 7.1 12.8 10.3 10.7 8.4 11.2 10.3  36.45 33.98 33.61 32.87 32.65 32.90 32.70 32.92 32.50 32.88 31.61 32.20 32.23 31.76 32.12 32.16 32.07 31.81 32.15 31.41 30.98 31.48 31.39 31.56 31.81 31.90 31.70 31.31 31.55 31.69 30.39 31.16 30.64 30.95 31.23 31.09 30.81  3.88 1.41 1.46 1.48 1.79 1.49 1.34 1.50 1.33 1.54 1.49 1.33 1.49 1.47 1.65 1.37 1.81 1.74 1.34 2.26 1.55 1.33 1.33 1.86 1.97 1.37 1.62 1.35 1.36 1.39 1.56 1.57 1.84 1.39 1.47 1.43 1.38  Ages (Ma)  204 Corrected (1) ±% 207Pb* ±% ±% 207Pb /235U 206Pb* /206Pb /238U 0.060 0.069 0.067 0.053 0.062 0.063 0.052 0.055 0.058 0.050 0.057 0.054 0.054 0.053 0.058 0.053 0.052 0.050 0.053 0.056 0.054 0.051 0.057 0.060 0.057 0.051 0.063 0.051 0.057 0.055 0.070 0.051 0.067 0.059 0.062 0.050 0.057  6.6 4.2 5.3 4.5 7.4 4.2 3.5 3.0 3.6 3.8 4.8 3.5 4.5 5.4 5.0 4.7 3.7 5.3 3.1 5.4 6.6 3.1 3.4 3.9 3.4 4.2 4.0 4.1 2.8 4.8 2.9 6.0 3.9 4.2 3.2 4.2 4.3  0.062 0.198 0.220 0.115 0.166 0.220 0.161 0.216 0.185 0.199 0.124 0.176 0.189 0.145 0.206 0.200 0.189 0.164 0.215 0.165 0.119 0.166 0.182 0.216 0.233 0.219 0.252 0.161 0.214 0.239 0.158 0.172 0.182 0.185 0.236 0.182 0.230  74.18 9.61 25.92 27.90 17.64 6.36 8.83 3.87 11.94 12.27 33.19 11.47 7.90 21.91 13.50 6.40 7.93 24.04 4.03 21.12 31.60 11.20 13.00 14.35 4.45 4.38 5.44 11.06 5.14 5.04 20.86 10.00 19.68 16.20 7.84 6.52 6.18  0.0261 0.0288 0.0293 0.0296 0.0298 0.0300 0.0301 0.0303 0.0303 0.0303 0.0306 0.0306 0.0307 0.0308 0.0308 0.0309 0.0309 0.0310 0.0310 0.0312 0.0313 0.0313 0.0313 0.0313 0.0313 0.0313 0.0314 0.0314 0.0314 0.0316 0.0316 0.0317 0.0317 0.0317 0.0317 0.0319 0.0323  4.12 1.48 2.18 1.71 1.90 1.51 1.39 1.50 1.45 1.67 1.84 1.42 1.52 1.67 1.79 1.38 1.84 2.02 1.34 2.42 1.80 1.40 1.46 2.02 1.98 1.37 1.63 1.41 1.38 1.39 1.77 1.59 2.05 1.58 1.53 1.44 1.40  err corr  0.055 0.154 0.084 0.061 0.107 0.238 0.157 0.387 0.121 0.136 0.056 0.124 0.192 0.076 0.132 0.216 0.232 0.084 0.333 0.115 0.057 0.125 0.112 0.141 0.444 0.314 0.299 0.128 0.269 0.276 0.085 0.159 0.104 0.097 0.195 0.221 0.226  204 206Pb/238U Calibration 206Pb* Error % /238U Age 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27  166.1 182.9 186.1 187.7 189.6 190.8 191.2 192.3 192.3 192.7 194.4 194.4 194.7 195.4 195.5 196.1 196.3 196.8 196.8 197.9 198.6 198.6 198.8 198.8 198.9 199.0 199.1 199.3 199.5 200.3 200.5 201.0 201.1 201.1 201.2 202.2 204.6  207 206Pb* /238U Age 7 3 4 3 4 3 3 3 3 3 4 3 3 3 3 3 4 4 3 5 4 3 3 4 4 3 3 3 3 3 3 3 4 3 3 3 3  106  172.3 182.8 185.1 192.5 191.7 190.1 193.7 191.8 193.6 193.2 199.1 196.3 196.0 199.1 195.9 196.8 197.6 199.5 196.8 200.6 203.8 201.4 200.6 198.9 198.0 198.8 197.2 202.4 199.6 199.1 203.8 203.5 203.1 202.9 200.3 204.2 204.3  7 3 3 3 4 3 3 3 3 3 3 3 3 3 3 3 4 3 3 5 3 3 3 4 4 3 3 3 3 3 3 3 4 3 3 3 3  Atomic Ratios Sample  S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B S09-16-01B  Spot  10268-20.1 10268-36.1 10268-54.1 10268-44.1 10268-51.1 10268-55.1 10268-43.1 10268-24.1 10268-49.1 10268-22.1 10268-35.1 10268-46.1 10268-16.1 10268-31.1 10268-38.1 10268-33.1 10268-15.1 10268-56.1 10268-32.1 10268-42.1 10268-8.1 10268-37.1 10268-12.1 10268-7.1 10268-11.1 10268-17.1 10268-52.1  ppm U  499.74 292.55 471.18 441.80 761.84 582.17 446.97 562.71 702.66 281.64 855.25 702.97 368.03 477.11 534.50 611.23 509.86 633.41 586.22 511.31 332.64 272.63 472.38 573.96 596.12 545.75 431.51  Th/U Y Hf ppm ppm  0.21 0.32 0.22 0.24 0.28 0.24 0.24 0.24 0.29 0.39 0.37 0.29 0.20 0.23 0.29 0.27 0.22 0.22 0.34 0.26 0.21 0.30 0.28 0.60 0.29 0.26 0.39  813 1058 618 748 688 928 731 933 1286 844 701 1148 526 842 688 933 714 1056 1125 893 571 457 955 1311 1124 802 792  10944 10770 11359 11353 12712 12466 11805 11160 11225 11027 11693 10851 11058 10887 11930 11461 11600 10834 12260 11366 11143 10322 10802 11202 11721 12093 11238  ppm 206*  13.00 7.66 12.35 11.60 20.13 15.39 11.83 14.90 18.63 7.48 22.79 18.81 9.88 12.84 14.40 16.47 13.75 17.09 15.82 13.80 8.98 7.37 12.99 15.93 16.94 16.54 20.70  % f206207  0.78 1.40 0.62 0.64 0.22 -0.12 0.72 0.30 0.25 1.82 0.35 0.20 0.00 0.97 0.17 0.25 0.18 0.31 0.71 0.45 0.92 0.00 1.03 0.99 0.35 0.73 0.23  204Pb /206Pb  4.5E-04 8.1E-04 3.6E-04 3.7E-04 1.2E-04 -7.2E-05 4.2E-04 1.7E-04 1.5E-04 1.0E-03 2.0E-04 1.1E-04 1.0E-32 5.6E-04 9.7E-05 1.4E-04 1.1E-04 1.8E-04 4.1E-04 2.6E-04 5.3E-04 1.0E-32 5.9E-04 5.7E-04 2.0E-04 4.2E-04 1.3E-04  ±%  35 13 38 30 32 144 103 38 141 24 60 35 100 37 296 33 40 48 16 20 146 100 28 31 63 126 40  Uncorrected 208Pb ±% ±% /206Pb 238U/ 206Pb 0.078 0.115 0.068 0.086 0.095 0.082 0.061 0.074 0.089 0.178 0.127 0.101 0.075 0.082 0.087 0.082 0.072 0.093 0.111 0.086 0.094 0.126 0.101 0.205 0.085 0.083 0.123  10.0 11.2 13.6 11.5 8.3 11.0 14.6 9.5 9.2 10.2 5.9 8.4 12.6 10.7 9.6 9.8 10.8 9.9 8.3 10.7 11.3 15.7 9.1 5.7 9.9 9.2 9.0  32.76 32.33 32.58 32.49 32.45 32.53 32.22 32.35 32.32 31.76 32.12 32.04 32.01 31.62 31.83 31.79 31.80 31.73 31.60 31.68 31.51 31.77 30.92 30.64 30.12 28.13 17.87  1.36 1.33 1.33 1.63 1.30 1.39 1.32 1.59 1.32 1.35 1.32 1.35 1.33 1.31 1.31 1.39 1.35 1.31 1.31 1.32 1.35 1.36 1.32 1.30 1.39 1.31 1.36  Ages (Ma)  204 Corrected (1) ±% 207Pb* ±% ±% 207Pb /235U 206Pb* /206Pb /238U 0.050 0.049 0.055 0.056 0.056 0.053 0.054 0.055 0.055 0.057 0.051 0.053 0.050 0.051 0.051 0.047 0.050 0.053 0.052 0.054 0.051 0.053 0.052 0.052 0.053 0.052 0.057  2.8 3.7 3.3 3.1 2.4 3.0 3.2 2.5 2.6 3.8 2.1 2.6 3.4 3.0 2.8 2.8 2.9 2.9 2.7 3.0 3.4 4.2 2.8 2.5 2.8 2.6 2.9  0.181 0.157 0.209 0.213 0.228 0.231 0.202 0.221 0.226 0.176 0.207 0.221 0.217 0.184 0.217 0.195 0.208 0.219 0.197 0.218 0.189 0.232 0.191 0.193 0.230 0.223 0.427  6.49 6.60 5.66 5.06 3.01 4.27 13.89 3.55 6.45 10.74 4.54 3.20 3.67 8.27 8.95 3.63 3.52 4.18 3.93 3.83 26.83 4.41 6.79 6.92 4.94 17.46 3.60  0.0303 0.0305 0.0305 0.0306 0.0308 0.0308 0.0308 0.0308 0.0309 0.0309 0.0310 0.0312 0.0312 0.0313 0.0314 0.0314 0.0314 0.0314 0.0314 0.0314 0.0314 0.0315 0.0320 0.0323 0.0331 0.0353 0.0558  1.39 1.34 1.35 1.64 1.30 1.41 1.52 1.59 1.37 1.43 1.34 1.35 1.33 1.36 1.40 1.39 1.35 1.32 1.32 1.32 1.91 1.36 1.35 1.34 1.41 1.60 1.36  err corr  0.214 0.203 0.238 0.325 0.433 0.329 0.109 0.449 0.213 0.133 0.295 0.421 0.362 0.165 0.156 0.384 0.382 0.316 0.335 0.345 0.071 0.308 0.199 0.193 0.286 0.092 0.378  204 206Pb/238U Calibration 206Pb* Error % /238U Age 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27 1.27  192.3 193.7 193.7 194.2 195.3 195.5 195.7 195.7 195.9 196.3 196.9 197.8 198.3 198.8 199.1 199.2 199.2 199.4 199.4 199.5 199.6 199.8 203.1 205.0 209.8 223.6 350.3  207 206Pb* /238U Age 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 3 3 3 3 4 5  107  193.8 196.5 193.8 194.0 194.4 194.5 196.2 195.2 195.2 198.3 197.3 197.5 198.2 200.5 199.1 200.3 199.7 199.3 200.5 199.4 201.1 199.0 204.8 206.6 209.8 224.8 349.5  3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 5  Atomic Ratios Sample  S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C S09-16-01C  Spot  10269-18.1 10269-26.1 10269-14.1 10269-17.1 10269-2.1 10269-25.1 10269-6.1 10269-3.1 10269-33.1 10269-38.1 10269-32.1 10269-16.1 10269-43.1 10269-42.1 10269-48.1 10269-5.1 10269-10.1 10269-30.1 10269-20.1 10269-45.1 10269-27.1 10269-41.1 10269-44.1 10269-13.1 10269-4.1 10269-22.1 10269-47.1 10269-11.1 10269-8.1 10269-7.1 10269-12.1  ppmU  184.97 387.65 237.36 240.26 191.68 172.70 202.65 167.02 250.64 351.99 401.90 519.54 443.97 208.18 165.30 269.33 327.93 219.32 564.70 306.84 245.25 349.51 217.86 224.77 430.04 588.63 293.94 307.80 456.14 677.39 954.11  Th/U Y ppm  0.41 0.47 0.37 0.49 0.34 0.41 0.41 0.40 0.59 0.64 0.72 0.50 0.45 0.40 0.32 0.46 0.39 0.62 0.56 0.48 0.38 0.60 0.45 0.31 0.37 0.54 0.59 0.60 0.61 0.73 0.90  445 939 608 811 453 504 694 573 1075 746 1988 1601 1034 779 517 928 998 1107 1687 723 730 1122 971 628 790 1449 1246 1267 1661 2189 1714  Hf ppm  10734 10281 10168 10066 11522 10652 10296 10138 10431 10803 9685 10229 10365 10026 10518 10154 10195 9996 9627 10366 10185 10383 9527 10855 11808 10410 10477 10323 10494 10345 10531  ppm %f206207 206*  4.54 9.76 5.99 6.12 4.93 4.45 5.27 4.37 6.56 9.24 10.57 13.69 11.79 5.53 4.40 7.17 8.74 5.85 15.07 8.19 6.57 9.37 5.84 6.06 11.62 15.93 7.98 8.39 12.45 18.58 27.11  2.93 0.36 1.68 1.62 1.08 0.00 0.54 1.90 2.14 1.03 0.53 0.72 0.77 2.44 0.72 0.77 0.18 0.50 -0.02 0.78 -0.04 0.98 -0.34 -0.17 0.54 0.00 1.54 1.15 1.19 0.30 0.54  204Pb /206Pb  ±%  1.7E-03 30 2.1E-04 32 9.7E-04 29 9.3E-04 47 6.2E-04 40 1.0E-32 100 3.1E-04 27 1.1E-03 42 1.2E-03 13 5.9E-04 28 3.0E-04 32 4.2E-04 23 4.5E-04 38 1.4E-03 31 4.1E-04 154 4.4E-04 25 1.1E-04 284 2.9E-04 147 -1.2E-05 1785 4.5E-04 40 -2.4E-05 1363 5.6E-04 53 -2.0E-04 249 -1.0E-04 150 3.1E-04 72 1.0E-32 100 8.9E-04 28 6.6E-04 32 6.9E-04 33 1.7E-04 36 3.1E-04 34  Uncorrected 208Pb ±% /206Pb 238U/ 206Pb 0.132 0.149 0.126 0.170 0.110 0.123 0.119 0.109 0.214 0.204 0.254 0.175 0.144 0.133 0.102 0.172 0.154 0.260 0.201 0.144 0.105 0.210 0.123 0.119 0.128 0.174 0.190 0.234 0.213 0.250 0.300  12.9 8.2 11.4 9.6 13.6 13.5 12.4 15.0 8.5 7.6 6.1 6.2 7.6 11.6 14.7 9.1 8.4 9.7 5.6 11.2 12.4 7.4 19.3 11.8 8.2 11.3 9.3 7.6 6.0 4.5 3.5  33.97 33.98 33.49 33.20 33.04 33.37 32.87 32.21 32.10 32.39 32.49 32.36 32.11 31.54 32.03 32.01 32.19 32.03 32.20 31.92 32.10 31.73 32.15 31.91 31.61 31.73 31.16 31.17 31.11 31.22 30.07  ±% 207Pb /206Pb 1.10 1.19 1.25 1.53 1.10 1.32 1.16 1.88 1.08 1.29 1.05 1.15 1.13 1.44 1.66 1.32 1.06 1.24 1.03 1.75 1.30 1.30 1.56 1.08 1.05 1.03 1.10 1.08 1.06 1.04 1.03  0.057 0.052 0.050 0.052 0.056 0.053 0.054 0.053 0.055 0.054 0.049 0.053 0.053 0.057 0.055 0.054 0.054 0.050 0.053 0.049 0.054 0.049 0.050 0.056 0.049 0.051 0.058 0.057 0.053 0.052 0.051  Ages (Ma)  ±% 207Pb* ±% /235U  4.2 3.1 4.0 3.8 4.1 6.1 4.1 4.6 3.7 3.2 3.1 2.5 2.8 3.9 4.5 3.6 3.2 4.1 2.4 4.7 3.8 3.4 4.3 3.9 2.9 2.4 3.7 3.4 2.7 2.2 1.9  0.125 0.197 0.146 0.158 0.195 0.220 0.208 0.153 0.153 0.190 0.188 0.196 0.197 0.155 0.211 0.202 0.224 0.195 0.227 0.182 0.233 0.175 0.229 0.247 0.194 0.222 0.197 0.208 0.187 0.216 0.211  204 Corrected (1) ±% 206Pb* /238U 25.79 4.01 12.99 18.01 9.35 6.20 5.28 20.50 8.88 6.79 4.82 4.30 6.46 19.67 19.78 5.52 9.07 14.45 6.23 8.61 9.65 11.79 14.05 5.45 8.25 2.63 9.64 7.92 8.61 3.15 4.13  0.0286 0.0293 0.0294 0.0296 0.0299 0.0300 0.0303 0.0305 0.0305 0.0306 0.0306 0.0307 0.0309 0.0309 0.0310 0.0310 0.0310 0.0311 0.0311 0.0311 0.0312 0.0312 0.0312 0.0314 0.0315 0.0315 0.0316 0.0317 0.0318 0.0319 0.0331  1.42 1.20 1.34 1.72 1.18 1.32 1.17 2.05 1.12 1.32 1.06 1.16 1.17 1.64 2.00 1.34 1.18 1.44 1.09 1.78 1.41 1.40 1.78 1.11 1.12 1.03 1.18 1.14 1.13 1.05 1.05  err corr  0.055 0.299 0.103 0.095 0.126 0.213 0.221 0.100 0.126 0.195 0.221 0.271 0.181 0.084 0.101 0.242 0.130 0.100 0.176 0.207 0.147 0.118 0.126 0.204 0.135 0.393 0.122 0.144 0.131 0.333 0.255  204 206Pb/238U Calibration 206Pb* Error % /238U Age 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0  181.6 186.3 186.5 188.2 190.2 190.3 192.2 193.4 193.6 194.1 194.4 194.8 196.2 196.4 196.8 196.8 196.9 197.2 197.2 197.3 197.8 198.1 198.1 199.3 199.7 200.0 200.5 201.3 201.6 202.6 209.8  108  207 206Pb* /238U Age 3 2 2 3 2 2 2 4 2 3 2 2 2 3 4 3 2 3 2 3 3 3 3 2 2 2 2 2 2 2 2  185.5 186.5 189.6 190.7 190.8 189.6 192.2 196.5 196.7 195.2 195.7 195.6 197.1 199.5 196.9 197.4 196.3 198.2 196.5 199.1 196.9 200.3 197.4 197.7 200.9 199.8 201.7 201.9 203.3 202.9 210.8  2 2 2 3 2 3 2 4 2 3 2 2 2 3 3 3 2 2 2 3 3 3 3 2 2 2 2 2 2 2 2  Atomic Ratios Sample  S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D S09-16-01D  Spot  10270-39.1 10270-81.1 10270-95.1 10270-105.1 10270-69.1 10270-87.1 10270-2.1 10270-47.1 10270-70.1 10270-41.1 10270-44.1 10270-51.1 10270-29.1 10270-45.1 10270-11.1 10270-1.1 10270-88.1 10270-35.1 10270-5.1 10270-19.1  ppmU  591.35 355.08 224.37 444.62 667.58 297.95 603.23 463.79 435.16 822.67 405.98 432.88 883.77 386.73 474.60 356.09 129.22 167.27 803.09 412.08  Th/U Y ppm Hf ppm  0.23 0.22 0.40 0.35 0.26 0.35 0.27 0.27 0.29 0.27 0.26 0.15 0.32 0.25 0.24 0.33 0.39 0.33 0.23 0.42  911 558 450 816 1083 389 973 823 767 1131 519 438 1279 565 751 413 690 654 1654 1534  11151 11813 11713 11180 11396 10012 10880 10878 11171 12278 10940 12851 12263 11684 11846 10770 9407 9991 11440 9924  ppm 206*  15.00 9.13 5.79 11.49 17.45 7.86 15.94 12.26 11.58 21.89 10.80 11.54 23.59 10.47 12.89 9.67 3.52 4.61 25.18 16.56  %f206207 204Pb /206Pb  1.08 0.34 2.36 1.09 0.71 1.24 0.38 1.22 1.02 0.96 0.52 0.61 0.36 0.88 0.49 0.39 1.84 0.77 0.57 0.07  6.2E-04 1.9E-04 1.4E-03 6.3E-04 4.1E-04 7.2E-04 2.2E-04 7.1E-04 5.9E-04 5.5E-04 3.0E-04 3.5E-04 2.1E-04 5.1E-04 2.8E-04 2.3E-04 1.1E-03 4.4E-04 3.3E-04 3.9E-05  ±%  20 32 24 28 63 37 22 34 28 17 18 127 41 38 25 36 118 33 33 55  Uncorrected 208Pb ±% ±% /206Pb 238U/ 206Pb 0.086 0.077 0.137 0.125 0.087 0.118 0.093 0.122 0.095 0.090 0.098 0.056 0.108 0.082 0.070 0.112 0.145 0.140 0.064 0.169  9.4 12.1 11.3 8.2 8.2 10.5 8.3 9.7 14.8 7.2 10.0 13.3 6.3 11.6 11.2 9.8 14.3 13.4 12.7 6.1  33.50 33.31 32.53 32.88 32.64 32.15 32.39 32.10 31.95 31.98 32.11 32.02 32.06 31.46 31.48 31.50 30.93 30.93 27.24 21.36  1.04 1.06 1.83 1.05 1.14 1.07 1.04 1.21 1.05 1.03 1.05 1.05 1.06 1.06 1.05 1.09 1.30 1.13 1.36 1.05  207Pb /206Pb 0.052 0.052 0.054 0.057 0.051 0.056 0.053 0.054 0.051 0.052 0.056 0.052 0.053 0.054 0.052 0.054 0.063 0.059 0.054 0.057  Ages (Ma)  ±% 207Pb* ±% /235U  2.6 3.3 4.0 2.7 2.4 3.4 2.4 3.2 2.9 2.1 3.0 3.0 2.0 3.2 2.8 3.1 4.8 4.5 2.2 2.4  0.175 0.201 0.140 0.198 0.191 0.192 0.213 0.185 0.180 0.187 0.220 0.202 0.215 0.201 0.210 0.219 0.206 0.234 0.246 0.362  204 Corrected (1) ±% 206Pb* /238U  5.49 4.08 16.17 6.52 8.93 9.75 3.15 9.22 6.94 4.14 3.75 14.35 3.46 7.31 3.90 4.26 40.53 6.58 4.28 2.68  0.0295 0.0299 0.0300 0.0301 0.0304 0.0307 0.0308 0.0308 0.0310 0.0310 0.0310 0.0310 0.0311 0.0315 0.0316 0.0316 0.0317 0.0321 0.0365 0.0468  1.06 1.06 1.92 1.09 1.23 1.16 1.04 1.28 1.09 1.04 1.06 1.31 1.07 1.11 1.06 1.10 2.57 1.16 1.38 1.05  err corr  204 206Pb/238 U 206Pb* Calibration /238U Error % Age  0.193 0.260 0.119 0.167 0.137 0.119 0.330 0.139 0.157 0.251 0.282 0.091 0.310 0.152 0.271 0.258 0.063 0.176 0.321 0.393  1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0  207 206Pb* /238U Age  187.6 190.1 190.7 191.0 193.2 195.0 195.3 195.4 196.6 196.6 196.7 197.0 197.3 200.0 200.6 200.7 201.4 203.6 231.1 294.8  2 2 4 2 2 2 2 2 2 2 2 3 2 2 2 2 5 2 3 3  Spot name follows the GSC SHRIMP laboratory convention x-y.z; where x = sample number, y = grain number and z = spot number. Multiple analyses in an individual spot are labelled as x-y.z.z Uncertainties reported at 1s and are calculated by using SQUID 2.22.08.04.30, rev. 30 Apr 2008 f206207 refers to mole fraction of total 206Pb that is due to common Pb, calculated using the 207Pb-method; common Pb composition used is the surface blank (4/6: 0.05770; 7/6: 0.89500; 8/6: 2.13840) * refers to radiogenic Pb (corrected for common Pb) (1) based on 204 method; (2) based on 207 method Discordance relative to origin = 100 * ((207/206 age -206/238 age)/(207Pb/206Pb age)) Calibration standard 6266; U = 910 ppm; Age = 559 Ma; 206Pb/238U = 0.09059 Error in 206Pb/238U calibration is 1.0% and 1.27% for Calibrations 1 and 2 respectively (included) Standard Error in Standard calibration was 0.22% and 0.32 for calibrations 1 and 2 respectively (not included in above errors but required when comparing data from different mounts).  109  189.1 190.3 194.3 191.5 194.2 196.1 195.2 196.8 198.4 198.1 196.3 197.7 197.3 200.8 201.1 200.6 202.1 202.9 231.6 293.5  2 2 4 2 2 2 2 2 2 2 2 2 2 2 2 2 3 2 3 3  110  Figure 35: Concordia diagrams for U-Pb SHRIMP analysis of KGd zircons to examine relative cooling ages between variably deformed and altered samples in contact with one another. Data-point error ellipses are 2σ. A. Undeformed and unaltered KGd host rock (S09-13-03A, shown in Figure 6B) B. KGd enclave (S08-01-01, shown in Figure 6B). C. through F. Stacked sequence of variably altered and deformed KGd (from top to bottom: samples S09-16-01A, S09-16-01B, S09-16-01C, and S09-16-01D, shown in Figure 14C).  111  2.5.1.3 2.5.1.3.1  Results Suite One  Sample S09-13-01A composes massive, unaltered KGd. Twenty-nine zircons were analysed by SHRIMP and the 207Pb/206Pb of eighteen of these is 198.0 ± 1.6 Ma (Table 4, Figure 35A), which is interpreted as the emplacement age of this granodiorite. The youngest (182 Ma) and oldest (208 Ma to 310 Ma) results were rejected from the calculation of the mean and are interpreted to represent minor Pb loss and inheritance, respectively. Sample S08-01-01 composes altered granodiorite. Zircons for this sample were recovered by Apatite to Zircon, Inc. Forty-eight zircons were analysed by SHRIMP and the  207  Pb/206Pb of  38 of these is 200 ± 1.1 Ma (Table 4; Figure 35B), which is interpreted as the emplacement age of this granodiorite. The youngest (189 Ma to 194 Ma) and oldest (206 Ma to 213 Ma) results were rejected from the calculation of the mean and are interpreted to represent minor Pb loss and inheritance, respectively. 2.5.1.3.2  Suite Two  Sample S09-16-03A comprises banded gneiss which is pervasively weathered and stained by hematite from weathered gossanous sulphides within the rock mass. Gneissic bands are tightly folded, with more felsic bands (volumetrically 75% of the rock) measuring 3 mm to 1 cm in thickness, and darker coloured magnetite-rich bands (25 vol.% of rock) measuring 2 mm to 5 mm. Forty-nine zircons were analysed by SHRIMP and the  207  Pb/206Pb of thirty-  seven of these is 197.0 ± 1.4 Ma (Table 4; Figure 35C), which is interpreted as the emplacement age of this granodiorite. The youngest (166 Ma to 190 Ma) and oldest (206 Ma) results were rejected from the calculation of the mean and are interpreted to represent minor Pb loss and inheritance, respectively.  112  Sample S09-16-03B comprises massive KGd. K-feldspar megacrysts (20 vol.%) are 1 to 2 centimetres in length and are well aligned, possibly due to magmatic lineation. Plagioclase (40 vol.%) grains are several millimetres in size, eu- to sub-hedral, and do not exhibit visible solid state recrystallization textures. Plagioclase appears blue-green, possibly due to argillization or malachite weathering from weathered Cu-sulphides. Biotite (35 vol.%) is randomly oriented black books at the centimetres scale. Quartz is present as quartz eyes (5 vol.%). Twenty-seven zircons were analysed by SHRIMP and the Pb207/Pb206 of twenty-five of these is 197.6 ± 1.3 Ma (Table 4, Figure 35E), which is interpreted as the emplacement age of this granodiorite. The oldest (210-350 Ma) results were rejected from the calculation of the mean and are interpreted to represent inheritance. Sample S09-16-03C composes stage 3 deformed KGd. K-feldspar megacryst augens (20 vol.%) measure 4-5 mm locally but are up to 1cm. Plagioclase (40 vol.%) is present as microlithons up to several centimetres in length and are aligned with weakly anastomosing SP foliation. Plagioclase is blue-green in colour, either from argillization or malachite staining. Biotite (<5 vol.%) is present as weakly anastomosing SP foliation. Trace finegrained disseminated chalcopyrite and bornite are present as accessories. Thirty-one zircons were analysed by SHRIMP and the  207  Pb/206Pb of twenty-two of these is 197.8 ± 1.3 Ma  (Table 4, Figure 35E), which is interpreted as the emplacement age of this granodiorite. The youngest (182 Ma to 190 Ma) and oldest (210 Ma) results were rejected from the calculation of the mean and are interpreted to represent minor Pb loss and inheritance, respectively. Sample S09-16-03D composes massive KGd. K-feldspar (10 vol.%) is present mainly as randomly oriented megacrysts up to 3 cm. Plagioclase (35 vol.%) is present as euhedral to subhedral crystals and is chalky white, possibly due to argillisation. Biotite (25-30 vol.%) is  113  present as randomly oriented books 1 to 2 mm in size. Quartz (5 vol.%) is present as quartz eyes up to 5 mm. Patchy fine to medium grained epidote (3-5 vol.%) is associated with biotite, but it is not clear whether it is igneous in origin or related to alteration. Nineteen zircons were analysed by SHRIMP and the 207Pb/206Pb of fourteen of these is 197.6 ± 1.6 Ma (Table 4, Figure 35F), which is interpreted as the emplacement age of this granodiorite. The youngest (188 Ma to 191 Ma) and oldest (231 Ma to 295 Ma) results were rejected from the calculation of the mean and are interpreted to represent minor Pb loss and inheritance, respectively. 2.5.2 2.5.2.1  Re-Os Molybdenite Geochronology Samples  Three molybdenite-bearing samples were chosen to examine the absolute timing of mineralisation and assess its temporal relationship to the emplacement of the Minto pluton. Molybdenite associations and textures vary (see Appendix H ), complicating interpretations of relative timing. For example, molybdenite is associated with pegmatite veinlets, quartz veinlets, or biotite foliation, a possible indication of numerous mineralisation generations. Contact relationships between molybdenite and Cu-sulphides also vary, further obscuring interpretations of relative timing. Samples contain molybdenite with inclusions of chalcopyrite and/or bornite (Figure 36A and B), a possible indication that molybdenite growth overprints or crosscuts pre-existing Cu-sulphides. However, molybdenite may also share grain boundaries with copper sulphides, or occur as discrete masses (Figure 36C).  114  Figure 36: Photomicrographs showing textures in molybdenite samples suggestive of relative timing. A. Molybdenite along the margins of a quartz veinlet with chalcopyrite inclusions. Sample H510-276 from drill core at the north-west of the deposit. B. Close-up of chalcopyrite inclusions within euhedral molybdenite occurring in biotite foliation. It is not possible to determine whether Cu-sulphides have been crosscut by later molybdenite, have crystallized contemporaneously, or Cu-sulphides have intruded along grain margins. Sample H429-129 taken from drillcore from the south-east of the deposit. C. Kinked molybdenite from within a pegmatite dikelet indicating ductile deformation after emplacement. Dikelet is also folded. Rock is crosscut by fracture controlled propylitic alteration in the form of chloritized biotite and sericite growth in plagioclase. Sample H422-81.4 taken from drillcore in the southeast of the deposit.  115  Ductile deformation appears to have outlasted molybdenite mineralisation, as evidenced by kinked grains (Figure 36D). Propylitic alteration, controlled by brittle deformation, locally overprints ductiley deformed molybdenite (Figure 36D). 2.5.2.2  Analyses  Molybdenite separates from the three samples were prepared at Durham University. Whole rock samples were ground in a porcelain disk mill, collecting the +44 -210 µm (200–70 mesh) fraction. Molybdenite was then concentrated using heavy liquid techniques, and further purified by flotation using high purity water (MilliQ), magnetic separation, and/or removing impurities by hand under a microscope. After preparation, molybdenite from sample H510-276.5 was hand-picked using binocular microscope and tweezers at the University of British Columbia to separate it from abundant pyrite. The full analytical procedure for Re-Os age determinations at the University of Durham is described by Selby and Creaser (2001a; 2001b) and is only briefly noted here. Molybdenite samples were dissolved and equilibrated with a known amount of  185  Re and isotopically normal Os in  inverse aqua regia (2:1 16 N HNO3 and 12 N HCl, 3 mL) at 240°C for 24 h in a Carius-tube. Rhenium and Os were isolated and purified by solvent extraction, microdistillation, and anion exchange chromatography, and analysed by negative thermal ionization mass spectrometry on a Triton mass spectrometer using Faraday collectors. Total procedural blanks for Re and Os <2 pg and <0.5 pg, respectively, with an 187Os/188Os blank composition of 0.24 ± 0.02 (n = 2). Rhenium and Os concentrations and Re-Os molybdenite date uncertainties are reported in Table 5 and are presented at the 2σ level, which includes the uncertainties in Re and Os mass spectrometer measurement, spike and standard Re and Os isotopic compositions, and calibration uncertainties of  185  Re and  187  Os. Because a mixed  116  185  Re and Os tracer solution is used, uncertainties in weights of sample and tracer solution do  not affect the calculated age, and are not considered. However, sample and tracer solution weight uncertainties are considered in determining the uncertainty in the Re and concentrations. Uncertainty in the  187  187  Os  Re decay constant (Smoliar et al., 1996) are included  within errors within square brackets. 2.5.2.3  Results  Total rhenium contents of the three molybdenite samples ranged from 114.2 to 612.9 ppm. Osmium within molybdenite is predominantly radiogenic  187  Os (Stein et al.,1997; Selby and  Creaser, 2001) and range between 242 and 1269 ppb (Table 5). Calculated model ages for molybdenite are 197.4 +/- 0.8 [1.0] Ma in sample H422-81.4, 201.8 +/- 0.8 Ma [1.0] in sample H429-129.5, and 196.0 +/- 0.8 [1.0] Ma in sample H510-276.5. Table 5: Sample data from molybdenite  Sample no. H422-81.4 H429-129.5 H510-276.5  Sample Wt (mg)  Total Re (ppm)  ±  0.017 0.021 0.030  612.9 114.2 265.1  2.4 0.4 0.9  187  Re (ppm) 385.2 71.8 166.6  ± 1.5 0.3 0.6  187  Os (ppb)  1269.1 241.7 545.0  ±  Age (Ma)  ±  4.3 0.8 1.5  197.4 201.8 196.0  0.8 0.8 0.8  117  2.6 2.6.1  Summary Relationship between Igneous Activity, Alteration, and Deformation  The Minto deposit is hosted entirely within the arc-granitoid rocks of the Minto pluton. This host pluton was emplaced as multiple pulses into a dynamic setting. Solid state deformation and the progressive development of a penetrative foliation, SP, continued within the Minto pluton as different batches of magma were intruded and solidified. Copper-gold-silver mineralization is associated with potassic alteration in the form of biotite-magnetite, all hosted within the sheared granitoids. There is a weak correlation at the scale of individual shear zones between increased deformation intensity, folding of shear zones, potassic alteration, and copper grade (e.g., Figure 32, Appendix F ). At open pit and regional scales (Figure 33 and Figure 34, respectively) there is a spatial coincidence between folded shear zones and copper mineralization, and the trend of highest grade mineralisation is approximately parallel to the strike of folded shear zone axial planes. These characteristics, along with structural character described in Section 2.4, are the basis for cross section interpretations of Minto ore zone geometry shown in Figure 37.  118  119  120  121  .  122  Figure 37: Cross sections from the Minto deposit showing the interpreted geometry of deformation zones and mineralization. Regions of foliation are modeled as anastomosing zones with discontinuities due to tapering out of the zones, stoping of deformed rock into younger intrusions, or late faulting. Mineralisation is hosted within deformed rocks only, although the degree of solid-state deformation can vary greatly. Additionally, not all deformed rocks are mineralized. Sections A. and B. are through the Minto pit, and sections C. and D. are proximal to oriented drill holes 09SWC427, 09SWC429, and 09SWC431. Sections envelopes are 20 metres in width.  123  2.6.2  Geochronology  The majority of Minto zircons yielded  206  Pb/238U ages between approximately 197 Ma and  200 Ma, summarized in Figure 38. The first suite of samples represents the sample shown in Figure 6B and includes host Minto granodiorite (i.e., KGd, Sample S09-13-01A) and an enclave of altered KGd (Sample S08-01-01). Based on cross-cutting relationships, this enclave of propylitically altered granodiorite within unaltered granodiorite is older than its granodiorite host, consistent with the relative age dates for host rock and enclave. The second suite of four samples (S09-16-03A, S09-16-03B, S09-16-03C, and S09-16-03D) were collected from a sequence of vertically stacked deformed and massive granodiorites (Figure 28C and D) outcropping on the hangingwall side of the DEF fault in the Minto open pit. This alternating sequence of massive and deformed KGd is interpreted as representing shear zones cross-cutting a single, relatively undeformed, phase of intrusion, although it is possible deformation has developed within separate intrusions of KGd. The timing of molybdenite mineralisation is broadly coincident with emplacement of the Minto pluton. These ages young northward as 201.8 +/- 0.8 Ma (H429-129.5), 197.4 +/- 0.8 Ma (H42281.4), and 196.0 +/- 0.8 Ma (H510-276.5). Molybdenite in sample H429-129.5 is within uncertainty of the altered granodiorite enclave, sample S08-01-01, with an assigned age of 200.1 +/- 1.1 Ma Samples H422-81.4 and H510-276.5 have different dates, but are within uncertainty of one-another. The similarity of dates between these two samples is noteworthy because the two samples represent differing mineralisation textures, i.e., the first is associated with a quartz veinlet, and the second with a medium grained quartz-feldspar dikelet. Also noteworthy is the northward-younging trend of molybdenite ages (see Appendix H .  124  Figure 38: Annotated photograph of KGd samples showing summary of U-Pb SHRIMP zircon ages. A. Ages in Suite One, with an older enclave of KGd stoped into a younger KGd intrusion. B. Ages for Suite Two, with a vertically stacked sequence of variably deformed KGd with similar ages within error of oneanother.  125  An additional interesting feature is the occurrence of molybdenite within the two samples on either side of the DEF fault, a feature that offsets the main Minto deposit from additional mineralisation to the north of the fault. The similarity in ages between the samples could indicate that both halves of mineralisation occurred more or less contemporaneously. These ages contrast with the older age calculated for sample H429-129.5, sampled within a kilometre of sample H422-81.4. This relationship is suggestive of several mineralisation events, at least an early biotite-foliation hosted event and a later vein/dikelet event.  126  2.7 2.7.1  Discussion Petrogenesis and Emplacement Depth  Crosscutting relationships between KGd and Tlt indicate multiple stages of granitoid emplacement. Abundant fabrics within intrusions, e.g., K-feldspar alignment and clustering, mafic layering, and mafic magmatic enclaves are indicative of crystal movement within a melt, i.e., the Minto pluton was not fully crystallised during the development of these fabrics (Clemens and Wall, 1981; Vernon and Paterson, 2008). Whole rock geochemical work indicates Minto granitoids are calc-alkaline, peraluminous, and sub-alkaline, consistent with existing work by Mortensen (1999) and Tafti (2005). These traits are typical of granitoids in porphyry Cu-Au-Mo deposits, i.e., calc-alkalic, oxidised magnetite-series granitoids (Ishihara, 1981; Blevin and Chappell, 1992, 1995). Tectonic discrimination using Rb vs. Y+Nb (Figure 11A) suggests Minto granitoids are volcanic arc granitoids as defined by Pearce (1984), consistent with the current interpretation of the North American Coast Batholith belt, hosting the Aishihik batholith and Minto pluton, being a product of subduction (Anderson, 1990; Winter, 2001). KGd has molar ratios of Al2O/(CaO+K2O+Na2O) (or A/CNK after Clarke, 1981) of approximately 1.25, indicating a strongly peraluminous nature. This contrasts slightly with the interpretation of Tafti (2005) that massive KGd is only weakly to moderately peraluminous. Peraluminous granitoids contain more Al than can be accommodated within feldspars, stabilizing other aluminous phases, typically muscovite, Al-rich biotite, cordierite, garnet, or an Al2SiO5 polymorph (Zen, 1988). In KGd, epidote and locally garnet are abundant and reflect the peraluminous nature of the melt. Strongly peraluminous melts are thought to originate from melting of a sedimentary source (e.g., Chappell and White, 1974), melting of biotite-bearing  127  metaluminous felsic rocks (Miller, 1985), or by water-excess melting of mafic rocks (Ellis and Thompson, 1986). It is not clear which of these processes were in effect at Minto, although contamination of the pluton by sedimentary country rocks of the Yukon-Tanana may be responsible. This hypothesis of contamination is supported by inherited cores of YTT age within KGd zircon, discussed in section 2.5.1, U-Pb geochronology. Peraluminous rocks may be calcic, alkali–calcic, or calc-alkalic (Frost et al., 2001). KGd from Minto plots predominately within the calc-alkalic field, consistent with interpretations by Tafti (2005). The abundance of apatite, epidote and titanite, in addition to plagioclase, reflects the calcic nature of the melt. Several surface samples collected for this study plot within the calcic field, although this may be a reflection of Na, K, or Ca mobility during meteoric weathering. Primary variations in the MALI can be caused by either the sources or the differentiation history of magma. Frost et al. (2001) suggest that the MALI value for Cordilleran batholiths is related to the source region for the parent melts, with the plutons becoming progressively more potassic and alkalic away from the subduction zone. Empirically, the oxidised nature of the Minto pluton magma can be inferred from the browngreen colour of biotite in crossed polars (Chinner, 1960; Ishihara, 1998), the presence of magmatic magnetite, and the lack of ilmenite (Ishihara, 1977; 2004). This second feature places granitoids within the magnetite series of Ishihara (1977), representing magmas with high-oxidizing potential and significantly associated with sulphide-rich Cu, Au, Mo, Pb, and/or Zn deposits (Ishihara, 1977; Lehmann, 1982; Blevin and Chappell, 1992; Candela, 1992; Blevin and Chappell, 2004). The oxidised character of the Minto pluton is also indicated by whole-rock geochemical plots of SiO2 vs. calculated Fe2O3/FeO by Tafti (2005) as per Kirkham and Sinclair (1996).  128  Frost et al. (2001) used an [FeOTot/(FeOTot + MgO] index (Fe-index) to differentiate between rocks that are relatively Fe-enriched versus those that are relatively Fe-poor. KGd plots within the magnesian field (after Frost et al., 2001; Frost and Frost, 2008), indicating that Mg is relatively more abundant than Fe, consistent with Cordilleran granitoids in general (Frost et al., 2001). Magmatic epidote is a common accessory mineral in KGd. For granodiorite at watersaturated conditions and at ƒO2 equivalent to the NNO buffer, epidote has a wide magmatic stability field (Schmidt and Thompson, 1996; Schmidt and Poli, 2004a), crystallizing from intermediate magmas at pressures varying from 0.3 to 0.7 GPa (Zen and Hammarstrom, 1984; Schmidt and Poli, 2004a). However, stability at pressures as low as 0.2 GPa in water saturated conditions may be possible (Schmidt and Poli; 2004a). These pressures are consistent with the range of possible emplacement pressures for Minto granodiorites calculated by Tafti (2005) using Al in hornblende geobarometry between 0.27 GPa to 0.35 GPa (using the method of Blundy and Holland, 1990) or 0.62 GPa to 0.66 GPa (using the method of Holland and Blundy, 1994). These pressure calculations correnspond to paleodepths of approximately 10 km to 13 km and 22 km to 23 km, respectively, based on an assumed baric gradient of 0.036 km/MPa (density 2.8 g/cm3) taken from McCausland et al. (2002), who reported emplacement depths for the Aishihik batholith of 16-20 km based on calculated pressures 0.426 GPa to 0.555 GPa. Temperature calculations for Minto granodiorites by Tafti (2005) using the plagioclaseamphibole thermometer are 830 ºC to 857 ºC (using the method of Blundy and Holland, 1990) or 723 ºC to 738 ºC (using the method of Holland and Blundy, 1994). Temperatures of zircon crystallization for Minto granodiorites by Tafti (2005) are calculated as approximately  129  719 ºC to 747 ºC. These calculated temperatures are lower than predicted for calc-alkalic granitoid crystallization, but may be attributed to the effect of high activity of H2O (e.g., Piwinskii, 1968; 1973). Similarly, the bulk of McCausland et al.’s (2002) data indicate temperatures ~720-750 ºC for intruding granitoids in the Minto region, corresponding to depths around 20 km, with country rocks estimated to have an ambient temperature >480°C (assuming ~30°/km geothermal gradient). 2.7.2  Synopsis of the Crustal Environment During Emplacement of the Minto Pluton  Granodiorites of the Minto pluton are interpreted as a northern extension of the Granite Mountain batholith (Tafti, 2005), an Early Jurassic intrusion into the Yukon-Tanana Terrane (YTT; Mortensen, 1992). The YTT is an allochthonous pericratonic terrane accreted during the Mesozoic to the western margin of Laurentia, although the history of this event and of subduction-arc activity responsible for Early Jurassic intrusions is not well understood in the vicinity of the Minto deposit. Eastern movement of the YTT towards the Laurentian continental margin, along with consumption of the Slide Mountain ocean (Figure 38A), was initiated in the Late Permian (Mortensen, 1992; Colpron et al., 2006). However, subduction had likely ceased by the Middle Triassic (Beranek, 2006; Colpron et al., 2006; Colpron et al., 2007). Arc-subduction must have occurred between this time and the final assembly of the Intermontane belt during the Mid- to early-Jurassic (Mihalynuk et al., 1994) to account for the widespread mafic to felsic plutons of Late Triassic to Early Jurassic age intruding the metamorphic assemblages of YTT (Mortensen, 1992), including construction of the Minto pluton (Figure 38B). The tectonic event(s) responsible for deformation within the Minto pluton (Figure 38C, D) is also not known, although development of a regional orocline (Mihalynuk et al. 1994) could account for sufficient regional stresses. Also unclear are the  130  processes responsible for the rapid uplift of the pluton from at least 10-15 km depth (Mccausland et al., 2001; Tafti, 2005) to shallow crustal levels over ~10 My (Johnston et al., 1996b; Tafti, 2005) and exposure by the Upper Cretaceous (e.g., as depicted in Figure 39E).  131  132  Figure 39: Schematic of Minto deposit paragenesis. A. The arc-subduction event responsible for LateTriassic-Early Jurassic magmatism and emplacement within the Yukon-Tanana terrane (YTT) is not currently known. B. However, magmatism did occur, and resulted in the emplacement of the Minto pluton, interpreted as part of the Aishihik plutonic suite. C. Emplacement of the Minto pluton occurred in the ductile regime. Shear was accommodated within the pluton, with magmatic fluids and associated alteration confined to these discrete zones. D. Continued magmatic activity, deformation, and alteration developed, with corresponding cross cutting relationships. Continued deformation accommodated along shear zones led to folding of the zones and a resultant short-limb long-limb fold geometry. E. Cooling of the pluton and surrounding rocks allowed the development of brittle fractures. Retrograde alteration developed along fractures, possibly due to hydrothermal influx of previously exsolved fluids back into the cooled rock mass. F. Finally, rapid exhumation due to unroofing led to the exposure of the Minto pluton.  133  2.7.3  Pluton Emplacement and Ductile Deformation  Cross-cutting igneous relationships between granitoid intrusions of identical and contrasting composition observed in the Minto pluton are evidence that it was constructed through multiple intrusive stages. The size of granitic intrusions varies from sub-centimetre to at least tens of metres. Intrusions appear to have occurred both above and below the granodiorite solidus, as suggested by textures within and between intrusions. Intrusion into solidified rock is indicated by stoped enclaves of granitoid within younger intrusions, deformed mafic magmatic enclaves without solid state fabrics, intrusions that truncate pre-existing solid state foliation, and planar contacts between igneous bodies with magmatic alignment of K-feldspars along pre-existing solidified rock. Evidence that intrusions have been emplaced above solidus temperatures include accumulations of K-feldspar megacrysts, possibly the result of filter-pressed internal margins, and diffuse margins between intrusions. The origin of pegmatite dikelets is not clear but could represent filter-pressed residual magma that builds up pressure and induces multiple episodes of fracturing within and out from magma batches (Hibbard, 1987). The general prevalence of pegmatite dikelets within shear zones, relative to undeformed/unaltered rock, could be related to shear zones providing a useful anisotropy for focussing fractures and related water-rich dikelets. Deformation was partitioned into anastomosing shear zones that cut through intrusions, formed along contacts, and were possibly locally stoped by later emplaced slabs. The shear zones folded small dikelets creating further compositional banding in the gneiss. Shear zones and foliation have a shallowly dipping enveloping. Overprinting relationships between igneous intrusions and solid state foliations indicate an active shear zone during emplacement of magma during the construction of the Minto pluton. Magmatic fabric along the west margin of the Granite Mountain batholith has been suggested to indicate the nearby presence of the shear zone’s 134  northwesterly trending wall within an Early Jurassic continental magmatic arc (McCausland et al., 2002). There is no evidence for significant tilting of Granite Mountain batholith (McCausland et al., 2002) meaning shear zone orientation may be close to orientation it formed at; however, further work must be done, especially regarding the interpreted dip of the Minto conglomerate from drillcore (Mortensen, pers. comm.). Because country rock contacts were not observed in this study, it is not known whether ductile deformation was accommodated proximally in the Yukon Tanana Terrane. However, ductile deformation of granodiorites did occur within the Minto pluton during emplacement. Deformation could reflect intrusion into a regionally active crustal shear zone; or it might reflect emplacement related to heterogeneously partitioned strain associated with near vertical flattening and lateral expansion above an expanding magma chamber (de Saint-Blanquat et al., 2001; Pons et al., 2006; Stevenson, 2009). If it not intrinsically related to emplacement, the shear zones could represent a regional low angle shear zone system associated with regional shortening or lateral extrusion driven by far field kinematic boundary conditions larger than the Granite Mountain batholith itself. However, it could be that the thermal aureole of the growing batholith reduced the bulk competence of the crust surrounding the intrusion and this induced failure and lateral extrusion of a previously thickened crust by vertical shortening (Davis and Henderson, 1999; Arevalo et al., 2006). Either way, the Minto pluton could have been intruded as sheets into the active low angle shear zones. The rate of individual sheet emplacement and cooling, could be far shorter than the rate of ductile strain and hence they are almost like instantaneous brittle events within the longer lived shear zone. Minto has a present surface area of approximately 170 km2 (Figure 2), although it is fault bound within the surrounding Yukon Tanana Terrane, i.e., its original extents are not known. The thickness of the pluton is also not known, although drilling by Capstone indicates a thickness > 135  1 kilometre. The dimensions of the Minto pluton are within the order of magnitude as those described by Cruden (1998) in his models of timespans for arc pluton construction. Cruden (1998) predicts that tabular plutons 10 to 100 km wide and ~3 km thick can be emplaced between 100 years to 100 m.a. during tectonic deformation at rates of 10–10 to 10–15 s–1. Assuming a strain rate of about 10-13 - 10-13 s-1, based on representations of strain rates in arc environments where granitoids are crystallizing (e.g., Paterson and Tobisch, 1992; Johnson et al., 2004), temperature during deformation of Minto rocks would have occurred at approximately 500 °C based on observed deformation microtextures summarized in Table 6. However, this temperature range serves as only a rough estimate, as texture development relies on rate of grain boundary migration, dislocation climb, and dislocation production; each of these is in turn dependent on temperature, pressure, strain rate and water availability (Hirth and Tullis, 1992). Interlobate grain boundaries involving plagioclase or quartz are indicative of grain boundary migration (GBM) (Guillope and Poirier, 1979; Urai, 1986; Stipp et al., 2002). This style of recrystallization is described as occurring at approximately 500 °C (Stipp et al., 2002). Regions of recrystallized quartz exhibits a shape-preferred orientation forming a continuous foliation indicative of sub grain rotation (SGR) (Nishikawa and Takeshita, 2000; Nishikawa et al., 2004; Passchier and Trouw, 2005). This feature is indicative of dislocation creep with a temperature range 400 – 500 °C. Tapered deformation twins within plagioclase indicate minor dislocation glide and a deformation temperature between 400° and 500° C (Pryer, 1993; Borg and Handin, 1966; Ji, 1998). The presence of prograde myrmekite and minor internal kinking, suggest recrystallization in the form of dislocation climb and a temperature range of 450 – 600 °C (Borges and White, 1980; Gapais, 1989; Gates and Glover III, 1989; Tullis and Yund, 1991).  136  Table 6: Temperature estimates based on observed microtextures Temp °C / Microtexture  100  200  250  300  400  450  500  600  700  800  900  1000  Lobate plagioclase boundaries Quartz lobate boundaries Plagioclase deformation lamellae Myrmekite Quartz Sub grain rotation Biotite ductile deformation  137  Myrmekite mantling K-feldspar is most commonly understood to arise during deformation (e.g., Simpson, 1983; Watts and Williams, 1983; Simpson, 1985) due to dissolution-precipitation creep (Tullis and Yund, 1985; Simpson and Wintsch, 1989; Wintsch and Yi, 2002; Menegon et al., 2008). Myrmekite growths rimming K-feldspar were commonly adjacent to small patches of undulose extinction within K-feldspar, in keeping with Simpson and Wintsch’s (1989) model that myrmekite development during prograde metamorphism occurs at syn-tectonic stress concentration sites. Aligned biotite and/or chloritized biotite defines a tectonic foliation within deformed zones. This interpretation is based on criteria originally described by Trueman (1912; see also a review of foliation criteria by Williams, 1977), that biotite aggregate masses define a foliation which anastomose feldspar microlithons, and that folia are approximately co-planar. Although biotite foliation parallels the structural contact between zones, long axes of individual biotite books are poorly aligned and vary from neighbours by up to 30°. Biotite observed in samples commonly exhibits undulose extinction and kinking. These textures are described to occur at temperatures over 250 °C (Stesky et al., 1974; Stesky, 1978). SP is a penetrative, mesoscopically visible planar fabric developed with variable intensity at Minto. Feldspar, quartz, and biotite are recrystallized and earlier or syn-tectonic dikes are folded and have axial planes parallel to SP. This fabric has developed separately in granitoids temporally, as intrusions are emplaced, or spatially, as zones of partitioned deformation. Gapais (1989) summarizes three typical varieties of structural patterns for strain partitioned into granitic rocks and operative at various scales: (i) homogenously foliated domains, (ii) penetrative associations of foliation and small-scale shear bands, such as C-S structures, and (iii) discrete shear zones anastomosed around low-strain domains. Deformation zones at Minto are not homogenously deformed, and C-S fabrics are not present. However, foliated zones of rock were observed with the open pit to anastomose more competent rock, especially in areas of high 138  contrast between unaltered and altered rock. The orientation of SP is most commonly shallow and deformation intensity is weak to moderate. Local high strain and/or steep foliation observed in drill core may be indicative of anastomosing deformation zones (e.g., Bell, 1978; Mitra, 1978; White et al., 1980). Shear zones within the Minto pluton and associated SP foliation appear to have been folded with large sub-horizontal limbs and short, more steeply dipping limbs. This folding could have arisen due to a shortening event after pluton emplacement, while rocks were still hot, or regional shortening re-imposing itself after pluton emplacement. 2.7.4  Deformation, Permeability, and Hydrothermal Fluid Flow  The mineralised areas of the Minto pluton typically correspond to zones of deformation and foliation development. In addition, copper-gold-silver mineralisation is associated with metasomatism of host rocks. The relationship between deformation and hydrothermal alteration, i.e., preferential fluid flow along shear zones, is well known from metamorphic environments (Dipple and Ferry, 1992), with fluid flow in the direction of decreasing temperature likely increasing the ductility of silicate rocks by adding K+ to the rocks and thereby driving micaforming reactions (Dipple and Ferry, 1992). In addition, rocks in ductile shear zones are probably much more permeable during metasomatism (average permeability of 10 -17 to 10-15 m2) than rocks normally are during regional metamorphism (10- 21 to 10  - 18  m2) (Dipple and  Ferry, 1992; Géraud et al., 1995). Mineralisation at Minto is restricted to shear zones that are deformed and altered versions of the massive non-mineralised granodiorite. At Minto, contacts between mineralisation zones and wallrock are typically sharp with only rare cases of sulphides present in massive rocks, and even then only up to several centimetres from the contacts. Granodiorite protoliths are so ubiquitously barren that they are used as “blank” unmineralized  139  material during assaying. The highly mineralized shear zones indicate that the hydrothermal fluid was not in chemical equilibrium with the host rocks. In active shear zones at mid-crustal depths and temperatures >~500°C, increased permeability is likely inherently related to microdilatency through microfracturing. This deformation arises from heterogeneous strain between differently oriented crystals of the same mineral, minerals with different rheological properties, and different sized crystals (Kronenberg and Tullis, 1984; Wenk and Christie, 1991; Oliver, 2001; Oliver et al., 2006; Kolb, 2008). Strain softening and permeability enhancement can occur through positive feedback as hydrothermal fluids move through sites of microdilatency in developing shear zone (e.g., Yonkee et al., 2003). Strain softening can also occur due to the growth of micas at the expense of other silicate phases; e.g., conversion of hornblende to biotite during hydrothermal alteration, as is observed at Minto. Biotite is the main alteration phase associated with mineralisation at Minto, and is interpreted to have played a major role in facilitating ductile deformation. Biotite is a weak mineral under shear (Dipple and Ferry, 1992; Shea and Kronenberg, 1993; Wintsch et al., 1995; Johnson et al., 2004; Holyoke III and Tullis, 2006) and micas segregated in foliation planes have a strain softening effect disproportionate to their modal volume and can lead to strain rates much higher than the bulk rate (e.g. Shea and Kronenberg, 1993; Wintsch et al., 1995; Johnson et al., 2004). In the specific context of plutons, biotite has been invoked as the weakest mineral in the deforming carapace of the San Jose tonalitic pluton in Baja California, Mexico and thus initiated localized microfractures in a stress-supporting plagioclase framework (Johnson et al., 2004). These microfractures evolved into ductile microshear zones, along which biotite grains coalesced to ultimately form a mylonitic foliation at the highest strains. Thus a progressive transition from small scale brittle to ductile flow can be controlled by biotite content with other weakening mechanisms further promoting ductile deformation. Strain softening can also occur 140  through hydrolytic weakening of minerals, particularly quartz, and easier intracrystalline slip (Griggs, 1967; Kronenberg and Tullis, 1984; Kronenberg, 1994; Gleason and DeSisto, 2008). Fluid flow at Minto appears to have been pervasive through rocks undergoing shear and foliation development. The relative lack of brittle fractures and veins could be due to confining pressure during mineralisation, plus sufficient permeability within ductile shear zones to accommodate fluid flow. Rocks deforming by crystal-plastic processes are essentially inviscid and any pockets of fluid in the deforming rock mass will be constantly squeezed by the pressure of the rocks around them (Connolly and Podladchikov, 1998; Connolly and Podladchikov, 2004; Connolly, 2010). The length a pocket of fluid can reach (parallel to the external pressure gradient, approximately vertical in a non-deviatoric stress field) before significant squeezing occurs determines the maximum pressure that can develop at the top of the pinched fluid pocket, and hence the maximum effective stress in the rock surrounding it. This characteristic length scale of compaction is inversely proportional to temperature, and to the timescale of fluid generation and egress into the shear zone (Connolly, 2010). The lack of macroscopic veins could reflect insufficient fluid pressure generated at the end of a fluid pocket to lower the effective stress sufficiently to induce macroscopic tensile fracturing in the host rock, i.e., the fluid pockets are too short. This would suggest higher temperatures and less rapid fluid production than more highly veined hydrothermal systems like porphyry Cu deposits. Rather than travel via macroscopic fractures, the hydrothermal fluid at Minto likely moved pervasively through the shear zones as waves of vertically limited pockets that, at their upper ends, only reduced the effective stress sufficiently to promote microdilatency and enhanced permeability through increased levels of microfracturing and grain boundary sliding (as per Connolly, 2010). Rather than moving vertically through the shallow dipping shear zones, it is likely that the strong fabric anisotropy favoured microfracturing and fluid flow along the SP foliation at Minto. 141  This is similar to situations described by Pollard et al. (1998), where shear zones distractive during emplacement of mid-crustal intrusions (~14 km) are likely conduits for the egress of magmatic fluids as the magma cooled below the solidus. In summary, following the initiation of deformation at Minto, hydrothermal fluid infiltrated and altered the rock setting up a positive feedback mechanism where zones of strong alteration focussed fluid flow, leading to further alteration. Deformation was heterogeneously distributed and extensive fluid flow either did not follow all shear zone branches, or some shear zone branches developed after the cessation of hydrothermal fluid flow. Folding and the development of step shear zones likely outlasted hydrothermal fluid flow, as suggested by the ductile deformation of Cu-sulphides into and around fold hinges. 2.7.5  Hydrothermal Alteration  Magmatic hydrothermal fluids responsible for metasomatism and economic mineralization at Minto are evidenced in several ways. For example, (1) mineralization is hosted within the Minto pluton and was emplaced during the span of its emplacement, indicating ore is spatially and temporally coincident with intrusions. (2) Isocon analysis indicates that K2O, Fe2O3, P2O3, U, Th, Pb, Cu, Au, and Ag have been added ore-bearing rocks, and SiO2, Al2O3, CaO, Na2O, and Sr have been depleted. This element mobility can be attributed to metasomatism, provided the assumptions for isocon analysis are valid for these rocks. (3) The abundant potassic alteration associated with mineralization, K-metasomatism with biotite after hornblende plus magnetite, is a typical high temperature product of cooling magmatic fluids in feldspar bearing host rocks (e.g., Seedorff et al., 2005). (4) Sulphur isotope compositions of δ 34S (º/ₒₒ) values of 0.65 to 3.27. (+/- 0.2) (º/ₒₒ) for Cu-Fe-sulphides at Minto reported by Tafti (2005) are within the typical range of sulphides in porphyry deposits and are consistent with a magmatic derived fluid (Ohmoto, 1986; Taylor, 1987; Hattori and Keith, 2001; Simon and Ripley, 2011). (5) The 142  zonation of sulphide types as mapped by Pearson (1979) are interpreted to reflect changing redox conditions during mineralization, possibly due to the cooling of hydrothermal fluids. Based on the current understanding of constrains for mineralization at Minto fluid was not likely to have been generated by intrusions emplaced at the level of the Minto deposit itself, but rather by a deeper part of the magmatic chamber that was molten longer and more able to exsolve larger volumes of fluid. At Minto emplacement depths of ~16-19 km (corresponding to ~0.45 – 0.50 GPa (McCausland et al., 2002), an aqueous fluid will not exsolve from an intermediate magma with typical H2O contents of 4-6wt% until ~40-60% crystallization (see Cloos, 2001). At these pressures (and at temperatures of <800-1000°C) Cl will be strongly partitioned into an aqueous phase to produce a saline parental magmatic-hydrothermal fluid (Cline and Bodnar, 1991; Webster, 1992). Magmatic S will also partition preferentially into the exsolved fluid phase (Webster and Botcharnikov, 2011). Based on metal partitioning coefficients for S-Cl bearing aqueous fluids, metal will strongly partition into the fluid phase (Candela and Holland, 1984; Cline and Bodnar, 1991; Harris et al., 2003; Hack and Mavrogenes, 2006; Simon et al., 2006; Simon and Ripley, 2011). Consequently, crystallization of the Minto Pluton should have been capable of producing a metal-rich hydrothermal fluid. Molybdenite appears to post-date Cu-mineralisation based on its crosscutting relationship with Cu-sulphides and pyrite. Propylitic alteration is widespread, but is controlled predominately by fracture permeability, in contrast with the ductile controls on high temperature assemblages. The propylitic assemblages likely reflect an influx of lower temperature fluids after the main mineralising event. Multiple magmatic-hydrothermal cycles can play a role in modifying grade and contained metal of intrusion-related either by superposition of multiple mineralizing cycles, or through dilution by the emplacement of weakly-mineralized intrusions, e.g., in gold-rich porphyry copper deposits (Braxton and Cooke, 2005). Hydrothermal fluid events at Minto have 143  added Fe, K, S, Cu, Au, and Ag to the existing bulk composition. Al, Ca, and Na are reduced in sulphide bearing rocks. Hydrothermal mass transfer is responsible for zoned high temperature assemblages, most notably the transition from bornite-chalcopyrite mineralisation to pyrite only. Biotite-magnetite and Mo-sulphide development are important associated assemblages. Molybdenite is observed to crosscut chalcopyrite, bornite, and pyrite. Age dates based on Re-Os contents of three molybdenite samples suggests two, possibly three, Mo-sulphide events. Based on the observation of multiple intrusions and distinct Cu-Fe-sulphide cutting molybdenite, it is reasonable to invoke episodic hydrothermal activity in the deposit. However, it should be noted that chalcopyrite, bornite, or pyrite were not locally recognized as cross-cutting one-another, although emplacement textures have been completely overprinted by later deformation and thermal re-equilibration. Hydrothermal biotite and magnetite are spatially associated with sulphide development. These phases represent an enrichment through mass transfer of K and Fe. Such potassic metasomatism associated with granitoid intrusions is described to occur as juvenile waters cool away from intrusions (e.g., Warren et al., 2007). This alteration is in turn accompanied by silicification and dissolution of Ca-, Mg-, and Na-bearing phases (Giggenbach, 1984). At Minto, there is a zoning of bornite, bornite-chalcopyrite, chalcopyrite-pyrite, and pyrite (see mapping by Pearson, 1977). Similar zoning is known from the alkali Ridgeway deposit in Australia, where Cu grades are very similar to Minto (Wilson et al., 2003). This zoning could reflect progressive rock buffering of the fluid. Cooling leads to increased reduced sulphur owing to disproportionation; higher T = more oxidized fluid (more SO2) and get bornite stable over chalcopyrite. Cooling also leads to increased dissociation and lower pH. Progressive reduction of ore fluid by interaction with Fe-bearing minerals in host rock also releases H and lowers pH. Cooling fluid reduces Cu solubility so it is lost early. SO2 in porphyry-style deposits originates 144  from granitic melts and when dissolved in water disproportionates to give sulfate and reduced sulfur. This reaction continues as fluids cool and is the main control achieving sufficient H2S saturation to precipitate sulphide. As fluid alters wall rock and releases Fe2+, the Fe will drive the reaction to the right by removing H2S from solution to precipitate sulphide. Early magnetite reflects the oxidized nature of S in the fluid and most Fe in equilibrium with the fluid precipitates as magnetite rather than sulphide. This reaction could be respoinsible for the abundant magnetite observed at Minto. The most important mineral reaction during potassic alteration is the conversion of igneous hornblende, or in some cases pyroxene, to hydrothermal biotite. Thus the outermost reaction is preserved at the interface with fresh rock, and occurred first. At Minto, magnetite-biotite alteration is more widespread than Cu-mineralisation, and could represent the margins of individual mineralizing fluid events. The hypothesized deep, high-temperature origin for hydrothermal ore fluids at Minto would come with caveats. At the high degree of crystallization needed to exsolve an aqueous fluid, the expectation exists of more fractionated (more fluid rich) phases intruding late into the level of the Minto pluton exposed over the Minto property, or perhaps rising of these late fractionated melts higher in the crust taking fluids with them. CO2 is orders of magnitude more insoluble than water in a melt and will exsolve at higher pressures and lower levels of crystallization than H2O (Lowenstern, 2001; Baker, 2002). In felsic magmatic systems CO2 should form a fluid phase first and then H2O, Cl and S will preferentially dissolve into it. At the depth the Minto pluton was emplaced, the initial fluids exsolved are likely to be CO2-rich (Baker, 2002). There is no mineralogical evidence for the hydrothermal ore stage fluid at Minto having been CO2rich. Perhaps the early CO2-rich fluid phase separated from the magma early and was not involved in the ore-stage event; or perhaps fluids more fully exsolved to the H2O-rich endmember prior to separating from the magma. Perhaps the CO2 that should be present in deeply 145  exsolved magmatic fluids underwent phase separation into a CO2-rich lower density phase and a denser H2O-Cl-S fluid that carried much of the copper and Au. The lower density phase may have separated from the magma and not significantly interacted with the overlying rocks. Early, high temperature hydrothermal fluids derived from intrusions are commonly only in slight disequilibrium with igneous host rocks, hence large water volumes are needed to produce large scale volumes of potassic alteration (Dilles, in press). Potassic alteration at high temperature tends to occur with limited H+ availability, i.e., conditions of relatively limited acid supply, leading to the formation of hydrothermal biotite and local K-feldspar (Dilles, in press). Such assemblages are produced both from low salinity parental magmatic-hydrothermal fluids and brine-vapor mixtures (Dilles, in press). 2.7.6  Comparisons with Other Cu-Au-Magmatic Related Ore Systems  The Minto deposit type has been previously interpreted as a sedimentary copper deposit, orthomagmatic sulphide cumulate deposit, porphyry deopsit, and IOCG deposit. The linkage between hydrothermal Cu-Fe-sulphides at Minto and a magmatic hydrothermal source was first proposed by Pearson (1979) based on sulphur isotope values, although he noted that the phases were in disequilibrium. Tafti (2005) also examined sulphur isotope compositions for Cu-Fesulphides and reported δ 34S (º/ₒₒ) values of 0.65 to -3.27. (+/- 0.2) (º/ₒₒ). These values, δ34 S = 2 and -4%, are within the typical range of sulphides in porphyry deposits (e.g., Ohmoto, 1986; Taylor, 1987). Geochemical interpretations of Minto granodiorites show that they are oxidized (i.e., magnetite series) I-type, and peraluminous, broadly compatible with published granitoid compositions associated with Cu-Au-Mo generating rocks (Blevin, 2004). This study shows that construction of the Minto pluton occurred from ~197 to 202 Ma, contemporaneous with multiple phases of intrusion, continued ductile deformation, and mineralization. This interpretation contrasts with that of Tafti (2005) who suggests that 146  mineralization predates emplacement of the Granite Batholith, citing sharp intrusive contacts between unmineralized, massive quartz diorite of the Granite Batholith, strongly deformed, mineralized rock units, and a range of interpreted crystallization ages. Tafti (2005) classifies the Minto deposit as an “arrested” porphyry deposit, and suggests that the lack of symmetry for the mineral zonation to the west indicates that this ore zone is not in its original position and in fact is a piece of a deposit embedded in the intrusive phase as a raft. However, no evidence of largescale rafts or roof-pendants was observed during this study. Stoping of earlier rock was uncommon and at scales less than ~one metres, and alteration was observed both in early and late intrusions. Certain features of the Minto deposit are, however, similar to definitions of “classic” porphyry deposits. For example, ore mineral zonation can occur with bornite dominating the core of an orebody, especially at deeper crustal levels (Sillitoe, 2010). The size of the pluton hosting mineralization is variable from <1 km to >4 km. (Sillitoe, 2010), which could account for the size of the Minto pluton. Potassic alteration, specifically biotite alteration, is a common feature of hydrothermal alteration associated with porphyry mineralization (Sillitoe, 2010). However, one of the most distinctive features of porphyry deposits, veining, is rare in the Minto deposit (Titley, 1966; Sillitoe, 1973; Sillitoe, 2010). Thermobarometric data from Tafti (2005) and this study indicate emplacement depths of >15 km. Such depths are incompatible with the definition of porphyry deposits in current literature, with maximum depths described as <9 km (e.g., Sillitoe, 2010). Therefore, although the Minto deposit shares certain characteristics of a porphyry deposit, the conditions of formation are not compatible with the classic definition of a porphyry deposit. Workers at the Minto deposit have also interpreted the deposit as an IOCG, mainly due to an abundance of magnetite associated with mineralisation. However, Minto does not exhibit the essential characteristics of IOCG despoists described in current literature, e.g., brittle 147  deformation as the control on mineralizing fluids, local large scale hydrothermal breccias, depleted SiO2 contents in altered wall rocks, and the presence of abundant low Ti iron oxides or iron silicates (Sillitoe, 2003; Pollard, 2006; Groves et al., 2010). At Minto, none of these key characteristics are present, except for mineralisation being related to magmatic-hydrothermal activity. Alteration characteristic of IOCG deposits includes either calcic alteration (amphibole, epidote, and/or carbonate) and/or potassic alteration (biotite, K-feldspar, or white mica in high level, hydrolytic systems) (Groves et al., 2010). Both of these alteration types are observed at Minto, although such alteration also occurs in relation to porphyry deposits. Direct petrological and geochemical evidence, plus indirect isotopic evidence, implicate the devolatization of deep, volatile-rich mantle-derived magmas as the primary energy- and fluid-driving force for IOCG systems Groves et al., 2010); no such evidence has yet been discovered at Minto. The ductile shear-related permeability inferred at Minto is not typical of copper-gold deposits occurring is similar environments, i.e., porphyry or IOCG deposits where ore fluids are derived from convergent margin related granitoid intrusions. Porphyry and IOCG deposits are recorded as occurring in the upper crust with ore fluids generating fracture related permeability (e.g., Norton and Knight, 1977; Haynes and Titley, 1980; Sillitoe, 2003; Cathles and Shannon, 2007) including even the most deeply emplaced porphyry deposits as deep as 10 km (Seedorff et al., 2005). Pollard (2006) does describe deeply occurring IOCG deposits where magma–fluid systems cannot generate sufficient mechanical energy to fracture the host rocks; however, these deposits utilize a variety of existing fault-related structural traps for fluid permeability and do not initiate ductile deformation. Potassic alteration in the form of biotite-magnetite has been noted in the high temperature portion of porphyry deposits. In these environments, initial potassic alteration and minor metal precipitation occur from a metalliferous single-phase liquid or coexisting hypersaline liquid and 148  vapour as porphyry Cu systems cool through the 700 °C to 550 °C temperature range (e.g., Eastoe, 1978; Bodnar, 1995; Frei, 1995; Ulrich and Heinrich, 2001). Minto is a unique deposit because it is similar to porphyry deposits, e.g., mineralisation related to hydrothermal activity from granitic intrusions and biotite-magnetite alteration associated with sulphides, yet fundamental and defining characteristics set it apart, e.g., the depth of emplacement and importance of ductile deformation as a permeability pathway. Given the understandings of how the Minto deposit formed described in this thesis, in addition to earlier work, this deposit is believed to represent an entity within the continuum of hydrothermal deposits possible in the continental crust above arc subduction zones (Figure 39). These zones, i.e., regions below porphyry deposits, have been identified as prospective areas for over 40 years. Sillitoe (1973) proposed a genetic relationships between porphyry copper deposits and calc-alkaline intrusives, their relationship to convergent margins and magma production, and the potential for mineralisation below the observed bases of porphyry deposits. More recently, Seedorff (2008) refers to the region below the porphyry ore deposits as rarely described even though metallogenic hydrothermal fluids are widely believed to originate from below such deposits (e.g., Gustafson and Hunt, 1975; Burnham, 1979; Dilles, 1987; Carten et al., 1988; Redmond et al., 2004). Furthermore, Seedorff (2008) rationalises that magmatic systems likely continue for many kilometres beneath the orebody, into and perhaps beneath a cogenetic batholith, and that “these zones constitute an important source region of ore fluids and other components, and in certain geologic terrains the characteristics of root zones may point to previously undiscovered deposits.” That Minto Cu-Au-Ag mineralisation is coeval with the construction of a large plutonic granodiorite body, and that emplacement of mineralisation and igneous bodies occurred within the ductile regime at depths more than 10 kilometres, points  149  strongly to Minto representing a predicted but hitherto undiscovered deposit type beneath porphyry deposits.  150  151  Figure 40: Simplified schematic diagram of magma generation and emplacement within a subduction arc environment. The Minto deposit is interpreted as the product of normal geologic processes, i.e., created as the consequence of felsic magma emplacement and associated hydrothermal activity (as described by Richards, 2003). Although the deposit characteristics of Minto are unique, it is interpreted as part of the magmatic-hydrothermal continuum of deposits occurring in arc environments (as described by Robert, 2000). Deposit genesis at depth and within the ductile deformation regime is the nuique feature of this deposit that separates it from more common varieties occurring in subduction evironments, e.g., porphyry and epithermal deposits.  152  Chapter 3: Conclusion Cu-Au-Ag mineralisation at the Minto Deposit, YT, Canada, is hosted within ductiley deformed and altered granitoids of the Minto pluton. Variably foliated mineralized granodiorites and associated minor varients are juxtaposed with barren rocks by sharp contacts. On average, deformation zones observed in the open pit dip < 30º towards the northeast and are continuous over tens of metres with > 60º dipping margins; these margins are commonly truncated by much younger faults. The enveloping surface of the deformation zones can be mapped based on drill core and Cu-Au-Ag grade as sub-horizontal and laterally continuous over tens to hundreds of metres, although in reality the interface between deformed mineralized rocks and barren massive rocks vary on a sub-metre scale. Mineral foliation within deformation zones is typically parallel to structural contacts near said contacts, but internally varies in orientation and is locally strongly folded. . The contact between massive and deformed rocks is commonly cusp and lobate, or mullioned, also due to continued deformation accommodated by deformation zones. Cusp and piercement geometry have also developed for analogous reasons of rheological contrast within individual deformation zones between massive sulphides and adjacent internally deformed granodiorites. Deformation-related recrystallization of quartz, feldspar, and biotite is present to some degree in all Minto granodiorites, even those that appear undeformed in hand specimen. Biotite-magnetite (potassic) alteration is strongly correlated with mineralisation and deformation zones. Several hypotheses to explain the geometry of the deposit were proposed at the beginning of this thesis: (i) that contacts between massive and foliated rocks represent igneous contacts, and mineralisation predates the intrusive units, i.e., a “raft and roof pendant” model wherein a preexisting deposit was partially incorporated into a pluton, (ii) that contacts between massive and foliated rocks represent strain accommodation within a plutonic mass and mineralizing fluids 153  were focussed along deformation pathways, i.e,. “a shear-hosted hydrothermal deposit” model, or (iii) some combination of igneous activity, hydrothermal fluid flow, and ductile deformation, i.e., a “plutonism and mineralisation in an active shear zone” model. The data presented in this thesis are most consistent with the third option. Deformation zones observed during study are the result of partitioned strain into Minto granitoids and are preferentially localized in zones of hydrothermal alteration, especially the assemblage biotite + magnetite +/- sulphides. Magmatic anisotropies such as igneous contacts and K-feldspar megacryst-rich layering also aided strain partitioning. The presence of biotite during alteration promoted strain softening and continued deformation consistent with the work of Shea and Kronenburg (1993) and Johnson (2004), and created positive feedback link with hydrothermal fluid flow (as described by Dipple and Ferry, 1992). Granitoid magmas hosting mineralization were intruded as batches between at least 200.1 Ma to 197.0 Ma based on U-Pb SHRIMP geochronology of zircons. This timing is broadly contemporaneous with molybdenite mineralisation dates calculated for a separate suite of rocks at 202 (+/- 0.8) Ma to ~197. 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Zen, E., and Hammarstrom, J., 1984, Magmatic epidote and its petrologic significance: Geology, v. 12, p. 515.  168  Appendices  169  Appendix A Field Measurements Table A1: Axial planes measured in oriented drillcore HoleID  Depth  09SWC422  53.9  09SWC422  57.35  09SWC424  170.6  09SWC424  125.6  theta phi alpha beta gamma azimuth plunge strike dip dipdirection 240 60 50 170 40 233 -20 323 70 53 240 60 30 20 60 93 -57 183 33 273 236 57 50 20 40 124 -76 214 14 304 234 59 40 0 50 54 -71 144 19 234  Table A2: Axial planes measured in outcrop. NR = not recorded Feature  Trav  Easting Northing Elev AxialPlane Dip Fold_Kink 80708 384549 6943858 950 90 Fold_Open S09-25 384633 6944928 730 35 Fold_Open 384548 6945070 730 60 Fold_Kink S09-25 384633 6944928 730 30 Fold_S1 384463 6945098 730 35  AxialPlane DipAz 230 60 60 220 335  Fold_S1 Fold_S1 Fold_S1 Fold_S1 Fold_Open  60 60 70 60 30  270 270 255 270 340  Fold_Open S09-25 384633 6944928 730 30 Fold_S1 384463 6945098 730 30  40 350  Fold_Kink 80708 384552 6943866 950 70 Fold_Open 384372 6945297 868 26  228 222  384640 384640 384640 384640 384463  6944938 6944938 6944938 6944938 6945098  730 730 730 730 730  Hinge Hinge Opening_Dir Trend Plunge up 125 5 150 5 165 40 up 165 35 Tight, opens to NE 175 20 up 180 25 down 185 30 down 190 25 up 315 20 open, opens to S 315 0 315 30 Tight, opens to NE NR NR NR NR  170  Table A3: Regional foliation measurements. Category  Trav  UTM_E  UTM_N  Elev  Foliation Foliation  S09-21  392382 384582  6948710 472 6944970 725  Dip Dip Azimuth 68 92 20 100  Foliation Foliation Foliation Foliation Foliation Foliation  S09-15 S09-15 S09-15 S09-24 S09-24 S09-24  384600 384600 384600 384460 384460 384490  6945161 6945161 6945161 6945088 6945088 6945122  728 728 728 730 730 730  50 50 50 45 55 30  35 60 75 280 295 265  Foliation  S09-24  384490  6945122 730  45  265  Foliation  S09-24  384490  6945122 730  35  285  Foliation Foliation Foliation Foliation  S09-24 S09-24 S09-24 S09-24  384515 384515 384515 384518  6945030 6945030 6945030 6945128  730 730 730 730  80 90 75 40  45 220 230 300  Foliation  S09-24  384518  6945128 730  30  315  Foliation  S09-24  384518  6945128 730  20  325  Foliation  S09-22  384538  6945022 730  35  0  Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation  S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25 S09-25  384626 384626 384626 384626 384637 384637 384637 384638 384638 384638 384638 384638 384638 384638 384638 384638 384638 384638 384638  6944926 6944926 6944926 6944926 6944932 6944932 6944932 6944927 6944927 6944927 6944927 6944927 6944927 6944927 6944927 6944927 6944927 6944927 6944927  50 60 65 60 30 35 45 25 20 40 15 50 20 10 50 50 50 60 55  225 250 250 260 105 205 215 40 50 75 80 100 120 130 200 205 215 215 250  730 730 730 730 730 730 730 730 730 730 730 730 730 730 730 730 730 730 730  Note In altered pG 'gneissic' bands parallel, local openly  Banded Gneiss Banded Gneiss Banded Gneiss, common complex internal deformation Banded Gneiss, common complex internal deformation Banded Gneiss, common complex internal deformation bGn- high grade cpy, bn bGn- high grade cpy, bn bGn- high grade cpy, bn Partially recrystallized KM; some carlsbad twins intact. Partially recrystallized KM; some carlsbad twins intact. Partially recrystallized KM; some carlsbad twins intact. Gneissic Foliation of compositional banding S1 axial planar to isoclinal folds S1 axial planar to isoclinal folds S1 axial planar to isoclinal folds S1 axial planar to isoclinal folds Continuous foliation Continuous foliation Continuous foliation S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn  171  Category  Trav  UTM_E  UTM_N  Foliation Foliation Foliation  S09-25 S09-25 S09-22  384638 384638 384530  6944927 730 6944927 730 6945018 730  Dip Dip Azimuth 60 250 80 255 60 55  Foliation  S09-22  384530  6945018 730  65  60  Foliation  S09-22  384530  6945018 730  65  70  Foliation  S09-22  384530  6945022 730  65  50  386543  6945651 735  84  70  Foliation  Elev  Foliation Foliation Foliation  S09-27-05 S09-27-05 S09-20  384540 384540 384603  6944954 736 6944954 736 6944925 736  70 80 30  180 190 60  Foliation  S09-20  384603  6944925 736  0  355  Foliation  S09-27-04  384605  6944941 736  60  235  Foliation  S09-20  384617  6944920 736  30  245  Foliation  S09-20  384617  6944920 736  5  275  Foliation  S09-20  384620  6944910 736  10  165  Foliation  S09-20  384620  6944910 736  5  170  Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation  S09-23 S09-23 S09-23 S09-23 S09-23 S09-23  384640 384644 384645 384645 384645 384645 384517 384517 384517 384522  6944909 6944923 6944923 6944923 6944923 6944923 6944979 6944979 6944979 6944978  736 736 736 736 736 736 745 745 745 745  50 5 80 40 50 30 85 80 75 60  65 70 40 70 80 95 25 35 245 250  384525  6944978 745  35  300  384439 384439  6945074 747 6945074 747  60 40  270 275  Foliation Foliation Foliation  S09-12-01 S09-12-01  Note S1? Polyphase def'n? Folded bGn S1? Polyphase def'n? Folded bGn Gneissic Foliation of compositional banding Gneissic Foliation of compositional banding Gneissic Foliation of compositional banding Gneissic Foliation of compositional banding pG with possible flow orientation or foliation. Oriented sample taken NA NA Rock poorly foliated moderately foliated (continuous folia). Rock poorly foliated moderately foliated (continuous folia). Very weathered; difficult to see fol'n. Abundant KM at contact Rock poorly foliated moderately foliated (continuous folia). Rock poorly foliated moderately foliated (continuous folia). Rock poorly foliated moderately foliated (continuous folia). Rock poorly foliated moderately foliated (continuous folia). Typical foliation Typical foliation Typical foliation Typical foliation Typical foliation Typical foliation near sample S09-13-01D near sample S09-13-01D near sample S09-13-01D Dragged down by local fault (fault ~60->110) Dragged down by local fault (fault ~60->110)  172  Category  Trav  UTM_E  UTM_N  Elev  Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation  S09-12-01 S09-12-01 S09-12-01 S09-14-02 S09-13-01 S09-13-01 S09-13-01 S09-13-01 S09-13-01 S09-13-01 S09-13-01 S09-13-01 s09-27-03  384439 384439 384439 384500 384519 384519 384519 384519 384519 384519 384519 384519 384707  6945074 6945074 6945074 6944987 6944978 6944978 6944978 6944978 6944978 6944978 6944978 6944978 6945028  747 747 747 747 748 748 748 748 748 748 748 748 748  Foliation  s09-27-03  384707  6945028 748  50  20  Foliation  s09-27-03  384707  6945028 748  80  175  Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation  S09-12-01 S09-12-01 S09-12-01 S09-12-01 S09-26 S09-26 s09-27-02 s09-27-02 s09-27-02 s09-27-02 s09-27-02 s09-27-02  384440 384440 384440 384440 384702 384702 384719 384719 384711 384711 384711 384711 384711 384711 384711 384711 384711 384714  6945088 6945088 6945088 6945088 6945033 6945033 6945040 6945040 6945038 6945038 6945038 6945038 6945048 6945048 6945048 6945048 6945048 6945056  750 750 750 750 750 750 757 757 760 760 760 760 762 762 762 762 762 762  25 30 20 30 45 50 30 50 20 40 40 75 10 20 20 45 30 40  0 10 20 355 55 80 65 70 30 85 95 50 60 90 100 80 110 5  384714  6945060 762  60  35  Foliation  Dip Dip Azimuth 20 280 60 280 30 290 40 240 85 25 80 35 30 140 85 225 75 245 60 250 35 300 20 350 70 0  Note  Foliation veers suddenly upward. Foliated KMGD. Measurement is of contact Foliation veers suddenly upward. Foliated KMGD. Measurement is of contact Foliation veers suddenly upward. Foliated KMGD. Measurement is of contact  Folded Q-F gneiss Folded Q-F gneiss Foliated eG Foliated eG Foliated eG Foliated eG Foliated eG Foliated eG  ***CROSSCUTS MAIN FOLIATION*** Small zone, ~10cm ***CROSSCUTS MAIN FOLIATION*** Small zone, ~10cm  173  Category  Trav  UTM_E  UTM_N  Elev  Foliation  384714  6945060 762  Dip Dip Azimuth 80 45  Foliation  384714  6945060 762  50  45  Note  Foliation  s09-27-01  384716  6945053 775  50  40  ***CROSSCUTS MAIN FOLIATION*** Small zone, ~10cm ***CROSSCUTS MAIN FOLIATION*** Small zone, ~10cm Continuous folia, recrystallized feld  Foliation  s09-27-01  384716  6945053 775  40  40  Continuous folia, recrystallized feld  Foliation  s09-27-01  384716  6945053 775  45  70  Continuous folia, recrystallized feld  Foliation  s09-27-01  384716  6945053 775  50  70  Continuous folia, recrystallized feld  Foliation Foliation Foliation Foliation Foliation Foliation Foliation  S09-11-02 S09-11-02 S09-11-02 S09-11-02  384772 384772 384680 384680 384827 384827 384782  6945118 6945118 6945105 6945105 6945009 6945009 6945050  779 779 781 781 795 795 805  15 20 15 25 55 40 75  80 135 30 125 35 110 60  Foliation Foliation  S09-26  384782 384700  6945050 805 6945270 808  15 30  65 70  Foliation  S09-26  384700  6945270 808  40  240  Foliation  S09-26  384700  6945270 808  30  270  Foliation  S09-26  384700  6945270 808  50  275  Foliation  S09-26  384700  6945270 808  40  285  Foliation  S09-26  384700  6945270 808  30  310  Foliation  S09-26  384700  6945270 808  20  350  Foliation  S09-26  384728  6945252 808  40  30  Foliation  S09-26  384728  6945252 808  25  55  Foliation  S09-26  384730  6945250 808  44  40  384769 384769 384769  6945111 820 6945111 820 6945111 820  25 10 15  20 30 70  Foliation Foliation Foliation  Fol'd GD-K Fol'd GD-K More intense foliation in narrow zone cutting weak foliation Fol'd tonalite Western Hinge portion - contacts (blue dots) Western Hinge portion - contacts (blue dots) Western Hinge portion - contacts (blue dots) Western Hinge portion - contacts (blue dots) Western Hinge portion - contacts (blue dots) Western Hinge portion - internal foliation (blue crosses) Western Hinge portion - internal foliation (blue crosses) Middle portion of interval - contacts (Red dots) Middle portion of interval - internal foliation (red crosses) Middle portion of interval - contacts (Red dots) pseudogneiss pseudogneiss pseudogneiss  174  Category  Trav  UTM_E  UTM_N  Elev  80810  384773 384769 384769 384764 384764 384764 384773 384773 384773 384773 384530  6945144 6945111 6945111 6945132 6945132 6945132 6945144 6945144 6945144 6945144 6945300  825 820 820 825 825 825 825 825 825 825 834  Dip Dip Azimuth 20 50 20 85 15 110 20 5 20 315 25 325 20 45 30 50 40 65 30 220 40 126  384390 384415 384415 384785 383927  6945200 6945250 6945260 6945181 6948433  834 834 834 835 838  50 40 25 30 20  36 36 12 110 163  Foliation  383965  6948371 838  65  40  Foliation  383965  6948371 838  75  70  Foliation  383965  6948371 838  20  80  Foliation  383965  6948371 838  60  240  Foliation  383965  6948371 838  70  240  Foliation  384960  6944525 840  60  36  Foliation  384962  6944528 840  32  20  Looks like a fracture which follows foliation, could be a joint  Foliation  384350  6945144 841  50  266  could be fault related but looks like fold eG  Foliation  384966  6944519 843  28  14  Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation Foliation  Foliation Foliation Foliation Foliation Foliation  80810 80810 80810  Note Fol'd GD-KQ pseudogneiss pseudogneiss Fol'd diorite Fol'd diorite Fol'd diorite Fol'd GD-KQ Fol'd GD-KQ Fol'd GD-KQ Fol'd GD-KQ At sample P017. Foln in small lensestruncated by small faults?  More intense foliation in narrow zone cutting weak foliation At Manana, crosscut by a more intense foliation (see cross cutting foliations) At Manana, crosscut by a more intense foliation (see cross cutting foliations) More intense foliation in narrow zone cutting weak foliation At Manana, crosscut by a more intense foliation (see cross cutting foliations) At Manana, crosscut by a more intense foliation (see cross cutting foliations) Foliation near gossen abundant siliceous 'layer' trending 304 deg. Foliation strike/dip = 306/60  175  Category  UTM_E  UTM_N  Foliation  384977  6944498 845  Dip Dip Azimuth 24 50  Foliation  384408  6945141 855  110 84  Foliation  384977  6944498 845  14  58  384400 384590 383976  6945250 850 6945310 850 6948351 853  60 60 35  335 40 210  Foliation Foliation  384611 384588  6945251 860 6945310 861  65 64  45 40  Foliation Foliation  384397 384419  6945252 864 6945260 875  60 20  334 350  Foliation Foliation Foliation  385159 385159 385159  6943445 887 6943445 887 6943445 887  40 22 70  50 70 232  Foliation  386170  6943762 887  70  105  Foliation  386170  6943762 887  60  265  Foliation  384888  6943798 903  50  50  Foliation  384889  6943796 903  30  74  Foliation  385029  6943635 903  24  72  Foliation Foliation Foliation  Trav  80804  Elev  Note Foliation in fG. Diplacement of about 1.4m with foliation below Sample SBH-08-002. Foliation @ 110/84. Lt green anhedral foliated plagioclase and black books of bt defining disjunctive cleavage. Sulphide bearing. Foliation in fG. Diplacement of about 1.4m with foliation above. Moderate mch staining  foliation in outcrop from Manana with xenolith of fG Fol'd tonalite Foliation in fG. Anastomizing cleavage of f.gr. platy bt. Microlithons of qz + plag up to 8mm or so in long axis diameter, plag milky white. Scattered kspar up to 1cm. No real obvious weathering, large amount of staining from mch, some tn. fG w dk green mafics SBH-P018. An easy to grab slab of slightly folded fG. Foliation on SW side @ 20/350 NW Foliation in fG. Foliation in fG Weak foliation in massive granitoid (pG) Trench with great foliated rock exposure + Mch Trench with great foliated rock exposure + Mch Foliation in fG. Trench trends 050, mch staining common, some az. Trench walls are extremely weathered, although measurements are still possible Foliation in fG; strongly weathered, very ms rich and limonitic Foliation in fG  176  Category  Trav  UTM_E  UTM_N  Elev  Foliation Foliation Foliation  385029 384876 384876  6943635 903 6943785 905 6943785 905  Dip Dip Azimuth 20 80 39 30 39 30  Foliation Foliation Foliation Foliation Foliation  384692 384710 385032 385032 384692  6945420 6945417 6943592 6943592 6944027  910 910 910 910 913  50 40 39 38 49  40 70 56 88 226  Foliation Foliation Foliation Foliation Foliation Foliation Foliation  383256 384678 384678 384881 384882 384882 384635  6943521 6944027 6944027 6943702 6943701 6943701 6943410  915 915 915 920 920 920 937  55 60 60 64 36 36 60  70 218 278 210 52 82 35  Foliation  384635  6943410 937  50  40  Foliation  384635  6943410 937  75  210  Foliation  384635  6943410 937  75  245  Foliation  384635  6943410 937  80  260  Foliation  384635  6943410 937  60  260  Foliation  384635  6943410 937  60  285  Foliation Foliation  384552 384549  6943866 952 6943858 953  78 70  254 314  Foliation  383754  6945737 955  50  265  Foliation  383754  6945737 955  55  275  Foliation  384845  6945852 955  55  60  Note Foliation in fG SW trending foliation in bt rich fg Foliation in bt rich fG (dip/dip dir = 39/030 SW)  Foliation in fG Foliation in fG Patch of exposed fG light mch staining. Contact ~ parallel to foliation. fG ~ 1m thick towards S. Bounded on S by peg Foliation Weak foliation; dip/dir = 60/278 Foliation? dip/dir = 64/210 Foliation in fG Foliation in fG dip/dir = 42/082 Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Trench, contact btwn DI1 and DI4. Fold hinges in float Foliation in fG fG with mch and rare f.gr. cpy. There's a steep anastomozing cleavage here, though difficult to tell whether it parallels foliation of fG. sbh-0807-01 Foliated showing near Marlboro Woman Foliated showing near Marlboro Woman Malachite Knob  177  Category  Trav  UTM_E  UTM_N  Elev  Foliation Foliation  384845 384456  6945852 955 6943815 957  Dip Dip Azimuth 60 100 60 50  Foliation  384456  6943815 957  64  230  Foliation  384515  6943830 957  64  252  Foliation  384469  6943812 960  22  44  Foliation  384469  6943812 960  40  50  Foliation Foliation Foliation Foliation Foliation  384653 384653 384653 384092 384127  6943533 6943533 6943533 6945731 6945752  960 960 960 975 975  50 25 70 75 80  40 145 210 270 50  Foliation Foliation Foliation Foliation Foliation Foliation  90622 90622 90622 90622 90622 90622  384732 384732 384732 384732 384732 384732  6945077 6945077 6945077 6945077 6945077 6945080  760 760 760 760 760 760  30 30 30 25 25 35  350 345 0 0 345 110  Foliation  90622  384732  6945080 760  10  40  Foliation  90622  384732  6945080 760  15  120  Foliation  90622  384732  6945080 760  5  10  Note Malachite Knob, higher strain zone Foliation in burned look rock (probably fG). Foliation in burned look rock (probably fG). Foliation. Rock looks like eG; about 30% bt, 15% qz, plag 25%, limonite 5%. Moderate alignment of phenos. Just to the SW there's uncommon, mod mch and az in same looking rock Foliation in burned look rock (probably fG). Looks like a switch in foliation - possible fold hinge. SAMPLE THIS TRENCH Foliation in burned look rock (probably fG). Looks like a switch in foliation - possible fold hinge. SAMPLE THIS TRENCH Trench with bt rich foliated T Trench with bt rich foliated T Trench with bt rich foliated T Fol'd GD and gneissic stuff slighty fol'd GD. KM fewer and smaller than usual (<1cm) 5 measurements from outcrop 5 measurements from outcrop 5 measurements from outcrop 5 measurements from outcrop 5 measurements from outcrop Shallow foln observed to be defd by cross cutting steep foln. Pic 2901778 Shallow foln observed to be defd by cross cutting steep foln. Pic 2901779 Shallow foln observed to be defd by cross cutting steep foln. Pic 2901780 Shallow foln observed to be defd by cross cutting steep foln. Pic 2901781  178  Category  Trav  UTM_E  UTM_N  Foliation  90622  384733  Foliation  90622  Foliation  Elev  Dip Dip Azimuth  Note  6945093 760  10  320  384732  6945080 760  15  0  90622  384733  6945093 760  30  240  Foliation  90622  384733  6945093 760  20  340  Foliation  90622  384733  6945093 760  20  350  Foliation  90622  384733  6945093 760  10  10  Foliation Foliation Foliation Foliation Foliation  90622 90622 90622 90622 90622  384733 384733 384733 384733 384631  6945105 6945105 6945105 6945105 6945167  760 760 760 760 760  60 20 20 30 90  50 22 355 350 240  Foliation Foliation  90622 90622  384625 384571  6945170 760 6945202 760  30 90  85 250  Poor Bt foln, difficult to measure (crenulated?). Pic 290-1784 Shallow foln observed to be defd by cross cutting steep foln. Pic 2901782 Poor Bt foln, difficult to measure (crenulated?). Pic 290-1784 Poor Bt foln, difficult to measure (crenulated?). Pic 290-1784 Poor Bt foln, difficult to measure (crenulated?). Pic 290-1784 Poor Bt foln, difficult to measure (crenulated?). Pic 290-1784 North of steep shear zone North of steep shear zone North of steep shear zone North of steep shear zone Small fol'd intrusion bounded by cataclasite. Steep foln zone or fol'd intrusion/horse? Foln // contact. Foln E of intrusion/horse High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  Foliation  90622  384571  6945202 760  80  80  High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  Foliation  90622  384571  6945202 760  70  255  Foliation  90622  384569  6945202 760  70  120  High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  179  Foliation  90622  384569  6945202 760  70  110  High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  Foliation  90622  384569  6945202 760  80  110  Foliation  90622  384569  6945202 760  80  120  High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  Foliation  90622  384569  6945202 760  80  120  High strain zone with sulfides. 2m region between high strain zones is very "milled" with poor foln, no minzn. Siliceous zone+sulfides along outside margin  Foliation Foliation Foliation Foliation  90622 90622 90622 Bench780-1  384560 384560 384570 384780  6945250 6945250 6945201 6945142  760 760 760 780  70 90 80 40  240 240 120 60  Foliation Foliation Foliation Foliation Foliation Foliation Foliation  Bench780-2 Bench778 Bench778 90805 90805 90805 90805  384775 384781 384765 384442 384443 384444 384445  6945145 6945415 6945153 6945330 6945331 6945332 6945333  780 778 778 847 848 847 846  45 20 30 25 20 60 30  40 25 55 290 270 35 270  v.weak foln in Gd v.weak foln in Gd Ccp+Bn in 20 cm high strain zone 10 interval of deformed Gd- fault bounded? Sharp contact with Gd below. Sharp contact with Gd, above  Foliation Foliation  90805 90805  384446 384388  6945334 847 6945298 874  25 55  225 300  Foliation  90805  384398  6945302 869  22  280  foln // contact foln// contact foln// contact Steep short limb See also sample S12-05-01A & pic 2396. foln// contact Defd zone above irma's Bn. Truncated to N by 55-->045 fault at 384400, 6945311 Defd zone above irma's Bn. Truncated to N by 55-->045 fault at 384400, 6945311  180  Category  Trav  UTM_E  UTM_N  Elev  Foliation  90805  384398  6945304 869  Dip Dip Azimuth 20 215  Note Defd zone above irma's Bn. Truncated to N by 55-->045 fault at 384400, 6945311  181  Table A4: Foliation measured in oriented drill core. HoleID  Depth  theta  phi  alpha  beta  gamma  Pole Az  Notes  Pole Plg  09SWC420  134  210  -61  20  240  70  265  -4 High strain zone  09SWC420  142  214  -61  40  330  50  339  -62 High strain zone  09SWC420  148  214  -61  65  80  25  167  -56 High strain zone  09SWC420  148  214  -61  55  275  35  272  -48 High strain zone  09SWC420  149  214  -61  60  170  30  209  -31 High strain zone  09SWC420  149  214  -61  60  340  30  300  -80 High strain zone  09SWC420  151  214  -61  60  350  30  309  -85 High strain zone  09SWC420  157  214  -61  25  350  65  19  -54 High strain zone  09SWC420  157  214  -61  35  345  55  7  -62 High strain zone  09SWC420  159  214  -61  60  260  30  259  -46 High strain zone  09SWC420  171  214  -61  60  0  30  34  -89 High strain zone  09SWC420  172  214  -61  45  310  45  310  -57 High strain zone  09SWC420  179  214  -61  60  340  30  300  -80 High strain zone  09SWC420  181  214  -61  40  220  50  245  -16 High strain zone  09SWC420  181  214  -61  60  225  30  240  -36 High strain zone  09SWC420  54  208  -61  55  290  35  275  -54  09SWC420  67  208  -61  55  70  35  141  -54  09SWC420  68  208  -61  55  90  35  153  -46  09SWC420  108  210  -61  55  0  35  30  -84  09SWC420  110  210  -61  50  90  40  150  -42  09SWC420  112  210  -61  55  70  35  143  -54  09SWC420  113  210  -61  60  45  30  138  -68  09SWC420  154  214  -61  50  255  40  265  -36  09SWC420  162  214  -61  60  140  30  191  -35  09SWC420  163  214  -61  45  200  45  229  -17  09SWC420  169  214  -61  55  320  35  302  -68  09SWC420  191  214  -61  70  115  20  186  -49  09SWC420  191  214  -61  65  100  25  175  -49  09SWC420  192  214  -61  70  300  20  258  -65  09SWC420  198  214  -61  60  120  30  180  -39  09SWC420  216  218  -61  60  255  30  260  -44  09SWC420  285  214  -61  65  40  25  155  -72  09SWC420  286  214  -61  75  265  15  241  -56  09SWC420  307  214  -61  50  50  40  126  -60  09SWC420  308  214  -61  40  30  50  89  -62  09SWC420  308  214  -61  45  35  45  103  -64  09SWC420  309  214  -61  55  40  35  127  -68  09SWC420  310  214  -61  75  35  15  187  -71  09SWC420  311  214  -61  75  40  15  185  -70  09SWC420  312  214  -61  70  25  20  177  -76  09SWC420  314  214  -61  60  10  30  121  -85  09SWC420  315  214  -61  65  20  25  158  -80  09SWC420  316  214  -61  70  20  20  181  -78  09SWC420  319  214  -61  45  345  45  357  -72  09SWC420  320  214  -61  60  30  30  135  -75  182  HoleID  Depth  theta  phi  alpha  beta  gamma  Pole Az  Notes  Pole Plg  09SWC420  321  214  -61  55  340  35  323  -78  09SWC420  323  214  -61  50  0  40  34  -79  09SWC420  323  214  -61  50  40  40  117  -65  09SWC420  328  214  -61  70  30  20  174  -75  09SWC420  332  216  -60  60  25  30  136  -78  09SWC420  333  216  -60  65  25  25  160  -78  09SWC420  335  216  -60  60  25  30  136  -78  09SWC420  338  216  -60  55  20  35  109  -78  09SWC420  345  216  -60  80  340  10  226  -69  09SWC420  347  216  -60  75  255  15  241  -54  09SWC420  348  216  -60  65  235  25  244  -42  09SWC422  54  240  -60  50  170  40  233  -20 Axial Plane  09SWC422  57  240  -60  30  20  60  93  -57 Axial Plane  09SWC422  58  237  -60  70  210  20  250  -42  09SWC422  62  237  -60  60  180  30  237  -30  09SWC422  62  237  -60  75  275  15  266  -58  09SWC422  65  237  -60  65  0  25  237  -85  09SWC422  68  237  -60  51  180  39  237  -21  09SWC422  69  237  -60  60  320  30  310  -70  09SWC422  152  239  -58  75  290  15  268  -60  09SWC422  152  239  -58  65  260  25  277  -47  09SWC422  165  239  -58  65  250  25  273  -44  09SWC422  170  239  -58  55  310  35  314  -63  09SWC422  226  240  -58  70  270  20  274  -52  09SWC422  227  240  -58  60  0  30  240  -88  09SWC422  229  240  -58  60  345  30  306  -82  09SWC422  232  240  -58  40  210  50  263  -11  09SWC422  233  240  -58  40  170  50  232  -8  09SWC422  234  240  -58  40  145  50  214  -12  09SWC422  245  240  -58  60  170  30  235  -28  09SWC422  245  240  -58  75  330  15  262  -69  09SWC422  246  240  -58  65  235  25  267  -39  09SWC422  264  239  -57  55  50  35  167  -63  09SWC422  264  239  -57  60  0  30  239  -87  09SWC424  65  233  -60  45  295  45  314  -50 [cms] bands of increased strain  09SWC424  78  233  -60  65  330  25  290  -75 [cms] bands of increased strain  09SWC424  79  233  -60  60  315  30  303  -68 [cms] bands of increased strain  09SWC424  79  233  -60  40  30  50  110  -63 [cms] bands of increased strain  09SWC424  126  234  -59  40  0  50  54  -71 Axial Plane  09SWC424  171  236  -57  50  20  40  124  -76 Axial Plane  09SWC424  58  233  -60  55  180  35  233  -25  09SWC424  95  234  -59  50  220  40  261  -23  183  HoleID  Depth  theta  phi  alpha  beta  gamma  Pole Az  Notes  Pole Plg  09SWC424  109  234  -59  55  265  35  285  -42  09SWC424  125  234  -59  20  245  70  293  -5  09SWC424  125  234  -59  70  355  20  243  -79  09SWC424  141  234  -59  65  180  25  234  -34  09SWC424  170  236  -57  40  125  50  195  -18  09SWC424  171  236  -57  80  125  10  223  -51  09SWC424  210  236  -57  65  310  25  287  -65  09SWC424  214  236  -57  65  260  25  273  -46  09SWC424  217  237  -56  65  340  25  276  -77  09SWC424  313  238  -55  60  230  30  264  -31  09SWC424  315  236  -54  60  270  30  281  -45  09SWC424  317  236  -54  50  240  40  275  -26  09SWC427  49  244  -60  65  330  25  301  -75  09SWC427  59  244  -60  55  10  35  115  -83  09SWC427  70  244  -60  70  20  20  212  -77  09SWC427  107  245  -59  65  330  25  300  -75  09SWC427  111  245  -59  65  330  25  300  -75  09SWC427  113  245  -59  80  320  10  261  -66  09SWC427  116  245  -59  75  285  15  275  -60  09SWC427  127  245  -59  70  310  20  287  -67  09SWC427  147  245  -59  65  180  25  245  -34  09SWC427  149  245  -59  70  110  20  216  -48  09SWC427  154  245  -59  45  35  45  137  -65  09SWC427  164  245  -59  65  340  25  295  -79  09SWC427  215  245  -59  50  290  40  317  -50  09SWC429  149  59  -60  35  180  55  59  09SWC429  143  59  -60  50  250  40  105  -33 local peglets- fol'n trustworthy?  09SWC429  56  56  -61  5  180  85  236  -24  09SWC429  63  56  -61  25  15  65  259  -53  09SWC429  64  56  -61  45  130  45  20  -23  09SWC429  68  56  -61  40  10  50  257  -68  09SWC429  71  56  -61  20  340  70  208  -47  09SWC429  101  59  -60  35  190  55  67  -5  09SWC429  101  59  -60  35  180  55  59  -5  09SWC429  129  59  -60  30  110  60  1  -16  09SWC429  130  59  -60  60  110  30  20  -41  09SWC429  131  59  -60  60  130  30  31  -36  09SWC429  144  59  -60  55  285  35  122  -52  09SWC429  148  59  -60  60  340  30  139  -80  09SWC429  171  60  -59  20  115  70  1  -5  09SWC431  46  237  -61  70  0  20  237  -81  09SWC431  51  237  -61  65  0  25  237  -86  09SWC431  55  237  -61  60  0  30  57  -89  09SWC431  91  242  -60  70  325  20  283  -73  09SWC431  90  242  -60  70  0  20  242  -80  -5 folding at 146.70?  184  HoleID  Depth  theta  phi  alpha  beta  gamma  Pole Az  Pole Plg  Notes  09SWC431  91  242  -60  75  325  15  268  -71  09SWC431  96  242  -60  75  300  15  273  -64  09SWC431  98  242  -60  80  0  10  242  -70  09SWC431  110  242  -60  76  0  15  242  -75  09SWC431  115  242  -60  70  0  20  242  -80  09SWC431  116  242  -60  70  345  20  267  -78  09SWC431  117  242  -60  60  290  30  300  -57  09SWC431  122  242  -60  70  10  20  223  -79  09SWC431  125  242  -60  60  285  30  298  -55  09SWC431  140  236  -59  60  0  30  236  -89  09SWC431  141  236  -59  55  340  35  339  -78  09SWC431  148  236  -59  70  270  20  271  -54  09SWC431  150  236  -59  75  295  15  266  -62  09SWC495  41  195  -61  65  145  25  177  -39  09SWC495  135  195  -60  55  45  35  113  -66  09SWC495  136  195  -59  55  10  35  70  -83  09SWC495  137  195  -59  45  50  45  102  -57  09SWC495  138  195  -59  80  0  10  195  -69  09SWC495  140  195  -59  65  135  25  172  -39  09SWC495  142  195  -59  55  120  35  158  -34  09SWC495  146  195  -59  70  70  20  155  -60  09SWC495  147  195  -59  45  235  45  234  -24  09SWC495  148  195  -59  60  85  30  144  -50  09SWC495  149  195  -59  70  20  20  165  -77  09SWC497  74  45  -56  50  0  40  225  -84 at 73.75, heavy Bt + Ccp - hinge?  09SWC497  76  45  -56  40  100  50  347  -27 at 76.7 - fold hinge?  09SWC497  74  45  -56  70  5  20  38  09SWC497  74  45  -56  40  100  50  347  09SWC497  80  45  -56  50  150  40  25  -27 Beta rotation Diffuse Peg, Bt defines no folia. -19 Hinge?  09SWC497  81  45  -56  70  310  20  82  -64 Possible folding PIC 2003-2007  09SWC497  107  45  -56  45  165  45  34  -11 Small shear zone  09SWC497  69  45  -56  55  0  35  225  -89  09SWC497  70  45  -56  60  180  30  45  -26  09SWC497  71  45  -56  65  170  25  40  -31  09SWC497  72  45  -56  70  60  20  8  -61  09SWC497  73  45  -56  60  110  30  8  -38  09SWC497  74  45  -56  70  60  20  8  -61  09SWC497  75  45  -56  70  5  20  38  -76  09SWC497  77  45  -56  80  340  10  53  -65  09SWC497  78  45  -56  65  90  25  5  -48  09SWC497  79  45  -56  65  60  25  358  -60  09SWC497  80  45  -56  50  150  40  25  -19  09SWC497  81  45  -56  60  260  30  86  -42  09SWC497  82  45  -56  35  5  55  237  -69  -76 Beta rotation  185  Appendix B Pit Maps  Figure B1: Map showing propylitic alteration and weathering mapped in the Minto pit during 2009.  186  187  Figure B2: Map showing zones of deformed rock and measurements of folition orientation observed during mapping in 2009.  188  Figure B3: Map showing the distribution of deformed rocks and orientations of faults observed during 2009 field work.  189  190  Figure B4: Map of joints/fractures oberserved during 2009 mapping. Measurements shown are for structures continuous at approximately bench scale, i.e., greater in length than 6m.  Appendix C Whole-Rock Geochemical Sample Locations Table C1: Location and descriptions of whole-rock geochem samples analysed at ALS Chemex. Sample of format Hxxx-yyy equate to Capstone exploration hole SWC-xxx, depth yyy metres. KGd = Minto granodiorite, Tlt = tonalite, Cpy = chalcopyrite, Bn = bornite, Mag = magnetite, Kfs = K-feldspar, KM = K-feldspar megacryst, Hem = hematite, Pl = plagioclase, Hbl = hornblende, Epi = Epidote, Bt = biotite, Qz = quartz, bGn = banded gneiss, FeOx = iron oxide, phlog = phlogopite, Gnt = garnet, cms = centimetres, mms = millimetres. Sample  PkgCode  UTM_E  UTM_N  Depth  Description  H424-212  4Lithoresearch  384531  6944491  212  H424-224  4LithoresearchQuant  384531  6944491  224  Massive KGd adjacent to foliated KGd (sample H424-224). Deformed KGd between intervals of massive KGd (sample H424-212 above and H424-252 below).  H424-252  4Lithoresearch  384531  6944491  252  H424-314  4LithoresearchQuant  384531  6944491  314  Massive KGd below foliated KGd (sampleH424224), Deformed KGd.  H424-323  4Lithoresearch  384531  6944491  323  Massive KGd  H427-115  4LithoresearchQuant  384956  6943813  115  H427-124  4Lithoresearch  384956  6943813  124  Deformed KGd with disseminated Cpy; compare with H427-125 Adjacent samples of massive KGd, foliated KGd, massive KGd. This sample is massive  H427-125  4LithoresearchQuant  384956  6943813  125  Adjacent samples of massive KGd, foliated KGd, massive KGd. This sample is deformed  H427-131  4Lithoresearch  384956  6943813  131  Adjacent samples of massive KGd, foliated KGd, massive KGd. This sample is massive  H427-70  4LithoresearchQuant  384956  6943813  70  With Cpy+Bn; compare with H427-125  H510-64  4Lithoresearch  383202  6945821  H587-141  4Lithoresearch  384141  6945938  141  ~Massive KGd. Blotchy textured, adjacent to deformed KGd and masisve KGd  H587-233  4LithoresearchQuant  384141  6945938  233  Deformed KGd adjacent to blotchy textured Tonalite, and KGd. KGd below is protolith?  H587-253  4Lithoresearch  384141  6945938  253  Massive KGd.  H666-68  4LithoresearchQuant  -  -  -  MDRU reference sample: QGRM-101  H666-70  4Lithoresearch  -  -  -  Duplicate of S09-22-01A  S09-02-9A  4Lithoresearch  383776  6945758  Surface  Outcrop just E of trench. Outcrop ~16m trending 170 deg; 'boulder' weathering. Kfs as KM (25-35%) very pale, almost grey. Good and tabular [2.5cm]. Pl (55%) [3-5mm]. Qz (10%) eyes. Bt (5%) pseudomorphing Hbl? Epi (3%) patchy but crystalline in mafic sites [1mm  S09-04-06A  4Lithoresearch  383197  6944378  S09-08-01A  4Lithoresearch  382654  6944715  1007  Rubbly outcrop of felsic intrusive rock in contact with Qtz-eye tonalite (KGd without KM?) and Tlt. Greenish tinge to plagioclase. Cleavage planes at 60-000 and 70-010. Massive KGd from regional trav. Patchy Epi.  S09-08-04A  4Lithoresearch  381289  6944784  Surface  Massive KGd. Moderate patchy eEpi.  KGd; nice and crystalline looking. Nice epidote.  191  S09-10-03B  4Lithoresearch  391014  6947669  Surface  S09-13-03A  4Lithoresearch  386926  6946023  Surface  Another great roadside exposure. Very fresh looking, broken apart as blocks. Hbl and minor Bt granodiorite. KGd (20%) as euhedral KM [2 cm]. Pl (30%) sub- to euhedral. Hbl (20-30%) blotchy, subhedral stubby crystals up to [1cm], long crystals up to [1cm], average size [5 mm]. Epi (5%) associated with Hbl/Bt. Bt (<2%) black and in equilibrium or replacing Hbl; possibly pseudomorphing Hbl. Qz (5%) anhedral. Possible weak foliation. Minor mafic magmatic enclaves. Massive KGd  S09-13-03B  4Lithoresearch  386926  6946023  Surface  Crowded Kfs porphyry variety of KGd  S09-13-03C  4Lithoresearch  386926  6946023  Surface  KGd with abundant mafic xenoliths  Sample  PkgCode  UTM_E  UTM_N  Depth  Description  S09-14-01Bi  4LithoresearchQuant  384590  6945165  730  BGn; so-called "siliceous ore"  S09-14-01Bii  4LithoresearchQuant  384590  6945165  730  BGn. Hem altered feldspars  S09-15-04A  4Lithoresearch  387024  6946222  767  Massive KGd with possible flow banding.  S09-16-01A  4LithoresearchQuant  384724  6945250  825  S09-16-01B  4Lithoresearch  384724  6945250  825  BGn. Pervasively weatherd and FeOx stained. 30>080, 45->065, 35->070. parallel banding. QzFeldspar 3mm->1cm. Mag bands 2mm to 5mm. Magnetic. Near massive KGd w slight fabric; flow banding?. KM 20% porph. Well aligned [1-2cm]. Emplacement aligned? Pl 40% eu-subhedral, no recrystallization, stained grn from Mch or argillization. Bt 35% generally as randomly oriented blk books [cms].  S09-16-01C  4LithoresearchQuant  384724  6945250  825  Def'd KGd. KM 20%, 4-5mm locally 1cm, some recrystallization-grain sized reduced. Pl 40% microlith [cm-cms] well aligned. Commonly stained Gnt. Bt 30%, black books [1mm], folia [cms] & anastomosing, almost continuous. Qz (<5%) as [mms] bands. Trace diss Cpy+Bn  S09-16-01D  4Lithoresearch  384724  6945250  825  Massive KGd. KM randomly oriented [->3cm]. Pl [35%] eu-sub-hedral, chalky white -> clay altered. Bt(25-30%) randomly oriented, books [1-2mm] altered to phlog? Qtz (5%) eyes [5mm] with visible subgrains? Epi (3-5%) w Bt, patchy alteration.  S09-17-05A  4Lithoresearch  388739  6947539  747  Massive KGd  S09-22-01A  4LithoresearchQuant  384535  6945018  730  Parallel banded Tonalite  S09-22-01B  4LithoresearchQuant  384535  6945018  730  Green-plagioclase (illitized?) tonalite which seems commonly "swirled" or mixed in with Bt+Cpy+Bn lithology (tonalite-porphyroclast bt-mag-gneiss); evidence of magma intrusions into un-solidified host?  S09-22-01C  4Lithoresearch  384535  6945018  730  S09-24-02Ai  4LithoresearchQuant  384539  6945075  730  Massive KGd adjacent to strongly deformed and altered rock. Contact rel'p with S09-22-01B unclear. Potential shear or fault contact? Steep limb of folding? Tonalite “porphyroclast” in contact with silceous CpyBn-mag-gneiss  S09-24-02Aii  4LithoresearchQuant  384539  6945075  730  Siliceous Cpy-Bn-Mag-gneiss  S09-25-02B  4LithoresearchQuant  384633  6944928  730  fold hinge of bGn  S09-69  4LithoresearchQuant  -  -  -  Ref sample: QGRM-101  S09-71  4Lithoresearch  -  -  -  Dup 2: S09-13-03B  192  Appendix D Whole-Rock Lithogeochemical Data Table D1: Analytical precision for geochemical analysis by Actlabs Ltd. See Table C1 for method used per sample.  193  Table D2: Table of whole rock geochemical data for samples listed in Table C1. Sample  SiO2 (%)  Al2O3 (%)  Fe2O3 (%)  MnO (%)  MgO (%)  CaO (%)  Na2O (%)  K2O (%)  TiO2 (%)  P2O5 (%)  LOI (%)  Total (%)  Ag (ppm)  As (ppm)  Au (ppb)  H424-212  67.21  16.14  3.77  0.085  1.16  3.97  4.46  1.89  0.35  0.15  0.49  99.68  < 0.5  < 0.5  <2  H424-224  65.77  15.13  4.35  0.136  1.28  3.83  3.36  3.23  0.38  0.21  0.55  98.22  < 0.5  < 0.5  <2  H424-252  65.09  16.76  4.02  0.088  1.35  4.37  4.41  2.16  0.32  0.15  0.46  99.18  < 0.5  < 0.5  <2  H424-314  62.78  15.52  4.94  0.051  1.52  4.19  3.41  3.07  0.43  0.25  2.35  98.52  1  < 0.5  59  H424-323  64.13  16.77  3.91  0.139  1.26  4.51  4.17  1.9  0.33  0.16  1.07  98.34  < 0.5  < 0.5  <2  H427-115  68.22  14.66  3.93  0.039  1.22  2.71  3.68  3.29  0.33  0.18  1.04  99.3  < 0.5  2.3  14  H427-124  65.01  16.17  3.95  0.070  1.31  3.79  4.32  2.13  0.36  0.17  0.93  98.22  < 0.5  < 0.5  <2  H427-125  63.53  15.28  6.05  0.072  1.69  3.07  3.73  2.9  0.45  0.25  1.22  98.24  < 0.5  < 0.5  9  H427-131  64.16  16.67  4.21  0.091  1.43  4.58  4.54  1.56  0.37  0.18  0.58  98.37  < 0.5  < 0.5  <2  H427-70  65.41  14.71  5.43  0.072  1.45  3.02  3.41  3.2  0.39  0.22  1.58  98.88  1.6  < 0.5  99  H510-64  64.75  16.50  4.22  0.104  1.43  4.71  4.49  1.93  0.39  0.18  0.47  99.17  < 0.5  < 0.5  4  H587-141  65.20  15.67  4.55  0.080  1.4  4.23  3.47  3.68  0.39  0.22  0.62  99.51  < 0.5  < 0.5  <2  H587-233  61.61  13.84  6.36  0.467  1.44  3.61  2.97  3.61  0.38  0.2  2.54  97.02  3.5  < 0.5  450  H587-253  63.84  16.49  4.24  0.093  1.32  4.58  4.56  2.04  0.35  0.16  0.98  98.64  < 0.5  < 0.5  <2  S09-02-9A  64.92  16.79  4.48  0.102  1.56  4.90  4.54  1.63  0.42  0.2  0.53  100.1  < 0.5  < 0.5  <2  S09-08-01A  64.82  16.96  4.26  0.126  1.45  4.76  4.69  1.72  0.38  0.17  0.43  99.78  < 0.5  < 0.5  <2  S09-08-04A  66.28  16.72  3.42  0.061  1.05  3.93  4.84  1.31  0.32  0.12  0.59  98.63  < 0.5  1.7  <2  S09-10-03B  63.98  15.89  4.64  0.120  1.59  4.50  4.10  2.59  0.40  0.23  0.51  98.54  < 0.5  < 0.5  <2  S09-13-03A  64.97  16.48  3.88  0.100  1.25  4.10  4.65  2.07  0.37  0.16  0.69  98.71  < 0.5  < 0.5  <2  S09-13-03B  63.11  16.43  4.90  0.106  1.21  3.19  3.54  4.66  0.40  0.14  0.76  98.45  < 0.5  < 0.5  <2  S09-13-03C  68.4  15.19  3.82  0.080  0.94  2.51  3.57  4.26  0.33  0.07  0.5  99.67  < 0.5  < 0.5  <2  S09-14-01Bi  79.64  0.68  15.55  0.060  0.28  0.40  0.05  0.13  0.27  0.04  0.22  97.33  7.8  0.9  693  S09-14-01Bii  57.09  11.48  13.92  0.147  1.95  1.44  1.21  5.42  0.62  0.25  2.37  95.89  11.6  1.9  1050  S09-15-04A  66.71  16.76  3.27  0.065  0.94  3.77  4.47  1.96  0.31  0.11  0.91  99.28  < 0.5  < 0.5  <2  S09-16-01A  77.70  4.73  8.45  0.032  0.05  0.07  0.46  3.08  0.09  < 0.01  1.75  96.42  28.2  5.7  4160  S09-16-01B  65.43  16.47  3.85  0.079  1.23  3.31  4.11  2.18  0.35  0.15  1.1  98.28  1.5  < 0.5  <2  S09-16-01C  64.54  14.73  6.57  0.104  1.57  2.28  2.58  4.95  0.42  0.31  1.41  99.44  3.1  5.5  409  S09-16-01D  65.16  16.67  3.68  0.064  1.19  3.46  4.35  1.81  0.39  0.15  1.19  98.12  < 0.5  < 0.5  <2  S09-17-05A  66.51  16.44  2.95  0.064  0.84  2.76  4.86  2.61  0.28  0.11  0.88  98.29  < 0.5  < 0.5  <2  S09-22-01A  51.37  12.67  16.99  0.150  1.69  3.85  2.47  2.86  0.90  0.3  3.53  96.77  5.5  < 0.5  5210  S09-22-01B  56.03  12.91  13.39  0.164  1.58  4.30  2.94  1.93  0.77  0.22  3.55  97.79  3.5  3.8  865  S09-22-01C  65.64  16.69  3.71  0.073  1.34  3.97  4.28  2.39  0.34  0.16  0.93  99.55  < 0.5  < 0.5  <2  S09-24-02Ai  52.64  16.72  11.29  0.166  1.97  4.53  4.77  1.45  0.48  0.16  1.84  96.02  11.1  < 0.5  13300  S09-24-02Aii  57.83  0.69  22.87  0.097  0.36  0.78  0.10  0.21  0.24  0.03  4.56  87.76  9.2  < 0.5  1530  S09-25-02B  62.14  11.60  14.01  0.107  1.36  1.10  2.01  4.58  0.41  0.14  1.24  98.69  3.9  < 0.5  1150  194  Sample  Ba (ppm)  Be (ppm)  Bi (ppm)  Br (ppm)  Ce (ppm)  Co (ppm)  Cr (ppm)  Cs (ppm)  Cu (%)  Cu (ppm)  Dy (ppm)  Er (ppm)  Eu (ppm)  Ga (ppm)  Gd (ppm)  H424-212  1164  2  < 0.1  < 0.5  26.6  5  13  0.2  NA  < 10  1.28  0.74  0.602  21  1.56  H424-224  1322  2  < 0.1  < 0.5  38.4  6  56  1  NA  30  2.19  1.32  0.804  18  2.51  H424-252  1985  1  < 0.1  < 0.5  37.0  6  <5  0.4  NA  < 10  1.59  0.93  0.686  20  1.86  H424-314  1514  1  0.2  < 0.5  34.3  6  <5  0.8  NA  2440  1.93  1.14  0.763  18  2.38  H424-323  1597  2  < 0.1  < 0.5  23.5  6  36  0.4  NA  < 10  2.30  1.28  0.708  20  2.30  H427-115  1168  2  < 0.1  < 0.5  26.9  5  9  0.7  NA  1170  1.74  1.05  0.615  18  1.92  H427-124  1565  2  < 0.1  < 0.5  39.2  6  <5  0.3  NA  < 10  0.94  0.54  0.613  20  1.42  H427-125  1275  2  < 0.1  < 0.5  43.7  8  11  1.5  NA  450  2.24  1.27  0.856  20  2.78  H427-131  1245  2  < 0.1  < 0.5  29.4  6  11  0.2  NA  < 10  2.10  1.26  0.722  20  2.27  H427-70  1081  2  1  < 0.5  29.0  8  57  1.1  NA  3370  1.75  1.04  0.632  20  1.96  H510-64  1762  2  < 0.1  < 0.5  29.8  7  56  < 0.1  NA  < 10  2.30  1.38  0.863  20  2.66  H587-141  1540  1  < 0.1  < 0.5  39.4  7  5  0.3  NA  30  2.39  1.42  0.844  18  2.61  H587-233  1247  1  0.3  < 0.5  33.6  7  10  0.9  1.69  NA  2.16  1.23  0.653  18  2.38  H587-253  2001  2  < 0.1  < 0.5  21.1  6  14  < 0.1  NA  10  2.05  1.24  0.711  20  2.23  S09-02-9A  1239  2  < 0.1  < 0.5  29.4  7  40  0.2  NA  < 10  2.84  1.64  0.895  20  2.99  S09-08-01A  1080  2  < 0.1  < 0.5  26.8  6  10  0.2  NA  10  2.18  1.27  0.731  20  2.34  S09-08-04A  2049  1  < 0.1  < 0.5  24.4  4  15  0.1  NA  < 10  1.63  0.87  0.627  19  1.80  S09-10-03B  1181  2  < 0.1  < 0.5  34.3  7  10  1  NA  20  2.11  1.24  0.785  20  2.34  S09-13-03A  1660  1  < 0.1  < 0.5  36.3  5  11  0.2  NA  < 10  2.64  1.59  0.809  20  2.96  S09-13-03B  4880  1  < 0.1  < 0.5  37.7  6  56  0.4  NA  < 10  2.63  1.51  0.840  19  2.81  S09-13-03C  2569  1  < 0.1  < 0.5  37.2  4  13  0.3  NA  < 10  2.00  1.21  0.605  17  2.11  S09-14-01Bi  84  <1  3.9  < 0.5  1.2  7  25  < 0.1  1.91  NA  0.14  0.08  0.041  11  0.18  S09-14-01Bii  5259  <1  6  < 0.5  3.8  13  67  0.8  2.52  NA  0.54  0.28  0.183  19  0.75  S09-15-04A  1786  1  < 0.1  < 0.5  28.8  4  16  0.3  NA  < 10  1.89  1.06  0.637  19  2.07  S09-16-01A  587  <1  15.9  < 0.5  0.3  5  9  < 0.1  2.52  NA  < 0.01  < 0.01  0.065  11  < 0.01  S09-16-01B  1074  1  < 0.1  < 0.5  18.1  5  61  0.7  NA  3230  0.58  0.31  0.405  21  0.76  S09-16-01C  1434  1  2  < 0.5  15.1  6  12  0.8  NA  4740  1.75  1.02  0.537  20  1.89  S09-16-01D  1579  1  < 0.1  < 0.5  55.8  6  14  0.5  NA  1210  0.84  0.46  0.522  20  1.25  S09-17-05A  2051  2  < 0.1  < 0.5  30.7  4  19  0.3  NA  < 10  1.91  1.14  0.649  20  2.08  S09-22-01A  2175  1  0.7  < 0.5  13.9  17  17  0.6  3.06  NA  0.95  0.51  0.526  23  1.29  S09-22-01B  1105  1  0.4  < 0.5  6.78  15  <5  0.6  1.71  NA  0.65  0.36  0.356  23  0.84  S09-22-01C  2468  1  < 0.1  < 0.5  24.8  5  69  0.4  NA  < 10  1.66  0.94  0.616  19  1.83  S09-24-02Ai  818  2  4  < 0.5  6.2  12  16  0.5  1.95  NA  2.70  1.57  0.611  24  2.56  S09-24-02Aii  158  <1  3.5  < 0.5  8.9  16  19  0.2  9.59  NA  0.81  0.45  0.209  7  0.87  S09-25-02B  1997  <1  0.8  < 0.5  8.3  8  22  0.4  1.21  NA  0.42  0.20  0.255  20  0.52  195  Sample  Ge (ppm)  Hf (ppm)  Ho (ppm)  In (ppm)  Ir (ppb)  La (ppm)  Lu (ppm)  Mo (ppm)  Nb (ppm)  Nd (ppm)  Ni (ppm)  Pb (ppm)  Pr (ppm)  Rb (ppm)  Sb (ppm)  H424-212  0.8  2.6  0.25  < 0.1  <5  13.50  0.126  <2  10  10.8  < 20  19  2.89  52  < 0.2  H424-224  1.5  3.5  0.44  < 0.1  <5  19.90  0.248  5  9.9  15.1  < 20  25  4.1  92  < 0.2  H424-252  1.3  2.8  0.32  < 0.1  <5  19.30  0.16  <2  5.3  14.1  < 20  17  3.91  47  < 0.2  H424-314  1.4  3.3  0.39  < 0.1  <5  17.50  0.168  <2  10  14.7  < 20  24  3.83  77  0.3  H424-323  1.2  2.8  0.45  < 0.1  <5  12.80  0.202  3  5.1  10.4  < 20  33  2.66  50  < 0.2  H427-115  1.5  2.9  0.35  < 0.1  <5  13.70  0.181  <2  9.7  11.8  < 20  11  3  67  < 0.2  H427-124  0.9  2.7  0.18  < 0.1  <5  21.90  0.098  <2  7.9  14.2  < 20  12  4.02  60  < 0.2  H427-125  1.6  3.4  0.44  < 0.1  <5  23.40  0.223  <2  11.9  17.4  < 20  18  4.7  95  0.3  H427-131  1.4  3.6  0.42  < 0.1  <5  14.70  0.237  <2  7.8  12.6  < 20  12  3.32  31  < 0.2  H427-70  1.5  3.3  0.35  < 0.1  <5  15.00  0.187  7  10.9  12.2  < 20  20  3.16  77  < 0.2  H510-64  0.9  2.5  0.46  < 0.1  <5  13.90  0.224  7  8  14.8  < 20  14  3.65  42  < 0.2  H587-141  1.5  2.9  0.48  < 0.1  <5  20.20  0.298  <2  12  15.7  < 20  17  4.28  61  < 0.2  H587-233  1.1  3.1  0.42  < 0.1  <5  17.30  0.239  5  9.9  14  < 20  79  3.66  90  0.3  H587-253  0.9  2.9  0.42  < 0.1  <5  9.83  0.204  <2  7.6  11.2  < 20  10  2.62  41  < 0.2  S09-02-9A  1.3  3.6  0.56  < 0.1  <5  13.40  0.279  4  10  15.4  < 20  10  3.7  36  < 0.2  S09-08-01A  1.4  3.3  0.43  < 0.1  <5  13.60  0.216  <2  7  11.6  < 20  11  3.03  38  < 0.2  S09-08-04A  1.0  2.6  0.31  < 0.1  <5  13.50  0.123  <2  3.4  10.1  < 20  6  2.66  22  < 0.2  S09-10-03B  1.5  2.9  0.41  < 0.1  <5  17.60  0.247  <2  9.4  14.2  < 20  9  3.77  62  < 0.2  S09-13-03A  1.3  3.2  0.53  < 0.1  <5  17.30  0.256  <2  10.1  15.8  < 20  8  4.16  38  < 0.2  S09-13-03B  1.3  3.9  0.51  < 0.1  <5  18.40  0.267  5  11.3  16.7  < 20  11  4.3  75  < 0.2  S09-13-03C  1.3  3.8  0.40  < 0.1  <5  19.90  0.237  <2  11  13.7  < 20  11  3.88  71  < 0.2  S09-14-01Bi  0.8  1.1  0.03  < 0.1  <5  0.52  0.011  <2  0.2  0.72  < 20  5  0.15  3  < 0.2  S09-14-01Bii  0.7  3.4  0.10  < 0.1  <5  1.87  0.057  9  7.8  2.72  < 20  33  0.54  85  < 0.2  S09-15-04A  1.1  3.3  0.36  < 0.1  <5  14.70  0.178  <2  7.7  11.8  < 20  8  3.15  36  < 0.2  S09-16-01A  1.2  1.1  < 0.01  < 0.1  <5  0.27  0.003  12  < 0.2  0.13  < 20  16  0.04  45  < 0.2  S09-16-01B  1.2  3.1  0.11  < 0.1  <5  11.10  0.059  6  6  7.68  < 20  12  2.23  66  < 0.2  S09-16-01C  1.5  3.6  0.34  < 0.1  <5  8.19  0.158  <2  8.5  8.31  < 20  40  2.04  100  < 0.2  S09-16-01D  1.1  2.4  0.16  < 0.1  <5  32.70  0.079  <2  4.3  17.3  < 20  9  5.26  44  < 0.2  S09-17-05A  1.2  3.2  0.39  < 0.1  <5  15.30  0.195  <2  9.5  12.7  < 20  9  3.36  51  < 0.2  S09-22-01A  1.1  5.0  0.18  < 0.1  <5  6.69  0.084  <2  12  7.28  < 20  11  1.71  83  < 0.2  S09-22-01B  1.1  3.9  0.13  < 0.1  <5  3.23  0.072  <2  8.3  3.95  < 20  8  0.87  71  < 0.2  S09-22-01C  1.2  3.3  0.32  < 0.1  <5  12.10  0.164  6  6  11.2  < 20  14  2.84  50  < 0.2  S09-24-02Ai  1.3  3.2  0.53  < 0.1  <5  2.44  0.261  5  7.2  5.92  < 20  19  1.1  39  < 0.2  S09-24-02Aii  0.6  0.9  0.16  0.3  <5  4.69  0.063  6  5.4  3.95  < 20  13  0.99  9  < 0.2  S09-25-02B  1.2  2.9  0.08  < 0.1  <5  4.42  0.036  <2  6.3  3.55  < 20  13  0.9  90  < 0.2  196  Sample  Sc (ppm)  Se (ppm)  Sm (ppm)  Sn (ppm)  Sr (ppm)  Ta (ppm)  Tb (ppm)  Th (ppm)  Tl (ppm)  Tm (ppm)  U (ppm)  V (ppm)  W (ppm)  Y (ppm)  Yb (ppm)  H424-212  4.9  <3  1.88  <1  783  0.28  0.23  3.2  0.25  0.108  1.74  69  < 0.5  7.2  0.72  H424-224  6.7  <3  2.95  <1  701  0.49  0.38  8.93  0.57  0.205  1.57  80  < 0.5  13.2  1.42  H424-252  7.1  <3  2.49  <1  847  0.14  0.28  3.26  0.24  0.141  0.52  74  < 0.5  9.2  0.96  H424-314  7  <3  2.87  <1  735  0.4  0.34  6.82  0.49  0.17  1.15  95  < 0.5  11.5  1.1  H424-323  9.8  <3  2.4  <1  824  0.24  0.38  3.02  0.33  0.188  0.6  69  < 0.5  13.1  1.24  H427-115  5.9  <3  2.27  <1  603  0.48  0.3  9.02  0.47  0.162  0.76  71  < 0.5  10.4  1.13  H427-124  3.9  <3  2.08  <1  780  0.24  0.18  5.43  0.3  0.081  0.53  70  < 0.5  5.4  0.55  H427-125  7.6  <3  3.37  2  653  0.67  0.4  10.4  0.59  0.199  1.47  105  < 0.5  12.9  1.35  H427-131  7.1  <3  2.64  <1  887  0.38  0.36  2.36  0.14  0.2  0.69  75  < 0.5  12.9  1.43  H427-70  6.8  <3  2.56  <1  615  0.6  0.31  9.02  0.46  0.167  1.46  84  < 0.5  10.3  1.12  H510-64  7.2  <3  3.1  <1  933  0.4  0.4  2.42  0.17  0.209  0.83  82  < 0.5  13.7  1.39  H587-141  6.1  <3  3.19  <1  781  0.77  0.42  6  0.22  0.233  1.88  89  < 0.5  15.1  1.76  H587-233  6.9  <3  2.89  <1  504  0.53  0.37  8.11  0.52  0.198  1.35  94  < 0.5  13.2  1.43  H587-253  6.9  <3  2.49  <1  920  0.36  0.35  1.51  0.14  0.186  0.56  74  < 0.5  12.6  1.23  S09-02-9A  7.7  <3  3.4  <1  905  0.52  0.48  1.82  0.14  0.252  0.7  88  < 0.5  16.5  1.73  S09-08-01A  7.3  <3  2.65  <1  901  0.27  0.38  2.25  0.16  0.193  0.6  81  < 0.5  12.8  1.34  S09-08-04A  5.1  <3  2.02  <1  985  0.11  0.29  1.54  0.08  0.131  0.25  54  < 0.5  8.9  0.84  S09-10-03B  8.7  <3  2.81  <1  827  0.51  0.38  5.08  0.22  0.198  1.38  84  < 0.5  13.3  1.41  S09-13-03A  8.4  <3  3.37  <1  728  0.59  0.46  2.74  0.13  0.249  0.67  59  < 0.5  16.6  1.64  S09-13-03B  7.6  <3  3.39  <1  822  0.7  0.46  3.48  0.27  0.239  1.03  92  < 0.5  15.9  1.66  S09-13-03C  5.6  <3  2.57  <1  659  0.58  0.35  3.55  0.25  0.202  0.87  61  < 0.5  13.1  1.45  S09-14-01Bi  1.1  18  0.19  <1  15  0.03  0.03  0.17  < 0.05  0.013  0.09  210  < 0.5  0.8  0.09  S09-14-01Bii  4.1  22  0.67  1  417  0.17  0.1  0.6  0.37  0.044  0.35  174  0.5  3.1  0.34  S09-15-04A  5.3  <3  2.42  <1  859  0.41  0.33  2.55  0.14  0.164  0.66  51  < 0.5  11.3  1.14  S09-16-01A  0.6  28  < 0.01  <1  137  < 0.01  < 0.01  3.28  0.23  < 0.005  0.38  59  < 0.5  < 0.5  0.03  S09-16-01B  3.4  <3  1.17  <1  672  0.16  0.11  6.62  0.38  0.048  0.62  62  < 0.5  3.6  0.35  S09-16-01C  7.1  <3  1.97  <1  676  0.37  0.3  8.31  0.68  0.151  1  93  < 0.5  10.9  0.98  S09-16-01D  2.9  <3  2.15  <1  931  0.19  0.16  6.29  0.18  0.069  0.45  62  < 0.5  4.9  0.47  S09-17-05A  4.5  <3  2.54  <1  825  0.44  0.33  2.65  0.19  0.174  0.79  48  < 0.5  11.8  1.2  S09-22-01A  2.7  26  1.56  1  537  0.23  0.18  1.32  0.41  0.077  0.78  343  < 0.5  6  0.51  S09-22-01B  2.5  11  0.91  <1  562  0.21  0.12  0.6  0.34  0.056  0.69  264  < 0.5  4.4  0.41  S09-22-01C  6.8  <3  2.29  <1  963  0.19  0.29  2.08  0.23  0.146  0.56  69  < 0.5  10  1  S09-24-02Ai  14.7  <3  2.14  3  948  0.28  0.44  0.5  < 0.05  0.241  0.61  110  1.5  14.6  1.64  S09-24-02Aii  1.5  114  0.87  2  28  0.22  0.14  1.52  < 0.05  0.066  0.57  162  3.3  5.1  0.42  S09-25-02B  2.9  10  0.63  <1  506  0.17  0.07  2.85  0.41  0.029  0.27  120  < 0.5  2.4  0.2  197  Sample  Zn (ppm)  Zr (ppm)  Mass (g)  H424-212  110  116  34.4  H424-224  110  125  31  H424-252  80  110  32.1  H424-314  50  120  30.2  H424-323  130  118  34.4  H427-115  40  103  27  H427-124  70  123  29.3  H427-125  80  124  28.9  H427-131  60  145  31.4  H427-70  80  118  31.2  H510-64  90  119  34.4  H587-141  40  111  33.5  H587-233  400  116  27.1  H587-253  80  139  31.3  S09-02-9A  70  142  33.8  S09-08-01A  90  130  30.9  S09-08-04A  40  114  29.3  S09-10-03B  70  112  30.3  S09-13-03A  60  131  30.9  S09-13-03B  70  154  30.6  S09-13-03C  50  150  32.1  S09-14-01Bi  110  45  37.2  S09-14-01Bii  280  163  34.3  S09-15-04A  50  133  29.7  S09-16-01A  30  35  30.9  S09-16-01B  100  129  29.9  S09-16-01C  160  132  29.2  S09-16-01D  70  95  27.8  S09-17-05A  50  130  30.5  S09-22-01A  240  203  30.1  S09-22-01B  240  161  26.8  S09-22-01C  70  135  34.1  S09-24-02Ai  270  145  30.9  S09-24-02Aii  520  32  36.6  S09-25-02B  160  112  27.2  198  Appendix E Isocon Calculations  Table E1: Geochemical data from Table D1 scaled here for use in isocon diagrams. KGd = Minto granodiorite. Bt = biotite, Mag = magnetite, Cpy = chalcopyrite, Bn = bornite, Py = pyrite, weath BGn = weathered banded gneiss. C0_Suite represents an averaged protolith of KGd. Sample C0_Suite H424-212 H424-252 H424-323 H424-314 H424-224 Protolith KGd KGd KGd KGd KGd KGd Alteration NONE NONE NONE NONE Bt-Mag, Bt-Mag, Cpy-Bn Cpy SiO2 20 20.61 19.96 19.66 19.25 20.17 Al2O3 18 17.45 18.12 18.13 16.78 16.35 Fe2O3 2 1.91 2.03 1.98 2.5 2.2 MnO 14 12.67 13.12 20.72 7.6 20.28 MgO 12 10.71 12.46 11.63 14.03 11.82 CaO 16 14.77 16.26 16.78 15.59 14.25 Na2O 8 8.03 7.94 7.51 6.14 6.05 K2O 5 4.86 5.56 4.89 7.9 8.31 TiO2 22 21.67 19.46 20.26 26.4 23.02 P2O5 10 9.43 9.43 10.06 15.72 13.21 Ce 16 14.02 19.5 12.38 18.08 20.24 Ga 20 21.11 20.1 20.1 18.09 18.09 Gd 12 8.88 10.58 13.09 13.54 14.28 Hf 25 22.03 23.73 23.73 27.97 29.66 La 18 15.59 22.29 14.79 20.21 22.99 Lu 10 6.88 8.73 11.03 9.17 13.54 Pb 6 7.86 7.03 13.66 9.93 10.34 Sc 14 10.41 15.08 20.82 14.87 14.23 Sr 24 21.2 22.93 22.31 19.9 18.98 Th 4 4.51 4.59 4.25 9.61 12.58 U 2 4.82 1.44 1.66 3.19 4.35 V 7 6.72 7.2 6.72 9.25 7.79 Zr 4 3.75 3.56 3.82 3.88 4.04  H427-124 H427-131 H427-70 KGd KGd KGd NONE NONE Bt-Mag, Cpy-Bn 19.93 19.67 20.06 17.48 18.02 15.9 2 2.13 2.75 10.44 13.57 10.73 12.09 13.2 13.38 14.1 17.04 11.24 7.78 8.18 6.14 5.48 4.01 8.23 22.28 22.59 23.88 10.69 11.32 13.84 20.66 15.49 15.28 20.1 20.1 20.1 8.08 12.92 11.15 22.88 30.51 27.97 25.3 16.98 17.33 5.35 12.94 10.21 4.97 4.97 8.28 8.29 15.08 14.45 21.11 24.01 16.65 7.65 3.32 12.7 1.47 1.91 4.04 6.82 7.3 8.18 3.98 4.69 3.82  H427-115 KGd Bt-Mag, Cpy 20.92 15.85 1.99 5.81 11.26 10.08 6.63 8.47 20.13 11.32 14.18 18.09 10.92 24.58 15.82 9.88 4.55 12.53 16.32 12.7 2.11 6.91 3.33  H427-125 KGd Bt-Mag, Cpy-Py 19.48 16.52 3.06 10.73 15.6 11.42 6.72 7.46 27.62 15.72 23.03 20.1 15.82 28.81 27.03 12.17 7.45 16.15 17.68 14.65 4.07 10.22 4.01  S09-16-01A KGd Bn-Cpy (weath BGn) 23.82 5.11 4.27 4.77 0.46 0.26 0.83 7.93 5.22 0.17 11.06 9.32 0.31 0.16 6.62 1.27 3.71 4.62 1.05 5.74 1.13  S09-16-01B S09-16-01C S09-16-01D KGd KGd KGd NONE Bn-Cpy NONE 20.05 17.83 1.95 11.93 11.35 12.32 7.4 5.61 21.48 9.43 9.54 21.11 4.32 26.27 12.82 3.28 4.97 7.22 18.19 9.32 1.72 6.04 4.17  19.79 15.92 3.32 15.51 14.49 8.48 4.65 12.74 25.54 19.5 7.96 20.1 10.75 30.51 9.46 8.62 16.55 15.08 18.3 11.7 2.77 9.05 4.27  19.98 18.02 1.86 9.54 10.98 12.87 7.83 4.66 23.82 9.43 29.41 20.1 7.11 20.34 37.77 4.31 3.72 6.16 25.2 8.86 1.25 6.04 3.07  199  Appendix F Graphical Logs The following graphical logs represent lithological, mineral, structural, and alteration observations for logged holes indicated in Figure 28.  200  201  202  203  204  205  206  207  208  209  210  211  212  213  214  Appendix G U-Pb Geochronology  Figure G1: Map of zircons analysed using SHRIMP II. 10265 = sample S09-13-03A, 10266 = sample S08-01-01, 10267 = sample S09-16-01A, 10268 = sample sample S09-16-01B, 10269 = sample S09-16-01C, 10270 = sample S09-16-01D, 6266 = GSC laboratory standard (206Pb/238U age = 559 Ma), numbers 1 through 12 = Temora standard (206Pb/238U age 417 Ma).  215  Figure G2: Example of reflected light (top half of image) and SEM backscatter (bottom half) imaging for four KGd zircons taken from sample S09-13-03A (10265). Circled numbers in red denote the location of SHRIMP probe points, checked visually after sample runs. Imaging for each zircon shown in Figure G1 is available as a separate digital appendix.  216  Appendix H Molybdenite Study Sample Locations  Figure H1: Map showing the location of molybdenite geochronology samples described in Section 2.5.2. Calculated model ages for molybdenite young northwards: 201.8 +/- 0.8 Ma [1.0] in sample H429-129.5, 197.4 +/- 0.8 [1.0] Ma in sample H422-81.4, and 196.0 +/- 0.8 [1.0] Ma in sample H510-276.5.  217  Detailed Sample Descriptions Sample H510-276.5 Table H1: Mineral descriptions for sample H510-276.5 Mineral Volume % Description Estimation Biotite  5 - 45  Black books in hand specimen; dark green in xpl. Grain size up to 1 mm long. Most frequently books share common alignment occur together, representing a discontinuous foliation. Isolated books are similarly aligned. Biotite foliation locally contains magnetite, pyrite, chalcopyrite, and garnet.  Plagioclase  25-40  Grainsize varies and is larger in areas with less biotite: 1 mm to 5 mm in higher grainsize portion of sample, 0.5 mm to 1 mm in more fine grained portion. POSSIBLE parallel growth twins- crosscutting oscillatory zoning [ask KEN HICKEY]? Stepped and tapered twins are uncommon. Rounded inclusions of quartz up to 0.5 mm are common. Patchy saussuritization is very rare.  Magnetite  20  Disseminated subhedral to anhedral grains more prevalent in finer grained section of sample. Masses up to 4 mm. Magnetite generally associated with biotite, also as individual grains. Shares sharp boundaries with all other minerals. Generally 'scrappy' looking. Rare inclusions of chalcopyrite and pyrite (fig); however, also observed as an inclusion within pyrite (fig)  Quartz  3  Predominately in larger grainsize portion of sample. Anhedral, up to 2 mm, and interstitial to feldspar. Very clear. Patchy subgrains are poorly defined- re-equiibration? Amoeboid intermineral boundaries. Weak sweeping undulose extinction is common.  Garnet  1; locally 20  red-orange euhedral to subhedral grains 1/5 mm to 1mm. Localized zones of abundance, either as disseminated or “vein-disseminated”, pseudo veinlets of individual grains. Occurs near magnetite and sulfides in this sample. Sharp boundaries with epidote. Very fractured. Chalcopyrite commonly within garnet.  Molybdenite  Accessory  disseminated and at margins of quartz-plagioclase dykelet. Grains anhedral and up to 0.5 mm. Uncommon inclusions of chalcopyrite; molybdenite post-dates chalcopyrite?  Epidote  5  Anhedral grains up to 1 mm. Common inclusions of chalcopyrite and pyrite when in association with these minerals. Sharp intermineral boundaries.  Anhydrite or Gypsum  Accessory  One discontinuous vein less than 1mm in thickness. After sample was polished for examination, became rough looking after about a week. Uncommon chalcopyrite and pyrite grains up to 1 mm disseminated within vein and along vein margins. Crosscut by quartz vein.  Carbonate  Accessory  Anhedral masses up to 5mm, interstitial to other minerals.  218  Figure H2: Minto diamond drill core sampled for Re-Os dating of molybdenite. Various textural occurrences of molybdenite are sampled from “separate” Minto deposits interpreted to have common origin. (a) Sample H510-276.5: molybdenite and proximal gypsum or anhydrite hosted in quartz vein or quartz-rich portion of pegmatite dyke. (b) Sample H42281.4: disseminated molybdenite occurring parallel to mica foliation (biotite altered to chlorite). Small diffuse pegmatite dyklets occur parallel to foliation. Crosscutting orangepink feature is fracture controlled hematite staining of plagioclase. (c) Sample H429-129.5: molybdenite occurring within deformed pegmatite dyklet.  219  Table H2: Mineral description for sample H422-81.4. Sample contains both massive and deformed zones. Mineral  Volume % Estimation  Description  Plagioclase  30-50  Anhedral phenocrysts 1 - 2 mm on average. Parallel and tapered twins are common and overprinted by ubiquitous patchy saussuritization. Grain boundaries with quartz are interlobate and deeply sutured.  Quartz  10  Anhedral and interstitial to feldspar, up to several millimeters. Very clear in hand specimen. Parallel subgrain boundaries are common. Fluid inclusion trails are ubiquitous.  Biotite  2, locally 15  FeCarbonate  3-5  Black books 1 - 3mm. Books are very well aligned. Light brown in xpl. In thin sections biotite as individual books; in core sample defines a discontinuous foliation where enough biotite is present and wraps plagioclase phenocrysts. Small pale orange veinlets up to 0.25 mm. Veinlets are continuous and typically follow intergrain boundaries. Also occurs between “jacked open” books of biotite.  Chalcopyrite Bornite Molybdenite  3-5 Accessory Accessory  Disseminated anhedral blebs up to 1 mm. Uncommon intergrowths of bornite. Fine grained anhedral growths typically within or along margins of chalcopyrite Very fine grained. Disseminated but occurring parallel to foliation along intermineral boundaries. Occurs in association with sericite.  Sericite  Accessory  Magnetite Carbonate  Accessory Accessory  Up 1 mm. Common "ragged" boundaries with plagioclase. Distinguished visually from muscovite based on the lack of tabular habit. Very fine grained disseminated anhedral grains. White veinlets less than 0.25 mm in diameter. Veinlets crosscut orange-pink carbonates and chalcopyrite. Most visible after application of dilute HCl acid.  Table H3: Mineral descriptions for sample H429-129.5 Mineral  Volume % Estimation  Description  Plagioclase  40  K-Feldspar  20  Quartz  25  Chlorite  10  Chalcopyrite  3  Anhedral to subhedral phenocrysts up to 3 mm. Heavily saussuritized; relict stepped and tapered twins are uncommon. Subhedral to anhedral grains up to 4 mm. Microcline twinning (?) is common (Figure X). Uncommon inclusions of quartz. Anhedral, seriate up to 1 mm, interstitial to feldspar. Deeply sutured subgrain boundaries. Interlobate boundaries with plagioclase. Biotite with grain size up to 1 mm. Disseminated and moderately aligned. Very commonly altered to chlorite. Disseminated anhedral blebs up to 0.5 mm. Uncommon intergrowths of bornite. In hand specimen is commonly mantled with dark grey, sooty mineral; possibly fine grained chlorite as observed in thin section. Chalcopyrite is a common inclusion within molybdenite (Figure X). Occurs in both host rock and pegmatite dyklet.  Molybdenite  3  Disseminated blebs up to 5mm. Occurs only within pegmatite dykelet.  Pyrite  Accessory  Anhedral, disseminated grains up to 0.3 mm. Occurs in both host rock and pegmatite dyklet.  Dyklets  NA  Fe-Carbonate  5-10  Quartzofeldspathic dykelets cross sample and appear to be partially deformed. Roughly 1/3 each of quartz, K-feldspar and plagioclase Veins up to 0.2 mm infilling fractures.  220  

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