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A Petrographic and Fluid Inclusion Comparison of mid-Cretaceous gold bearing veins near the 5 Moz Coffee… Lee, Well-Shen Apr 30, 2017

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  A Petrographic and Fluid Inclusion Comparison  of mid-Cretaceous gold bearing veins  near the 5 Moz Coffee Deposit, west-central Yukon  by Well-Shen, Lee  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF  BACHELOR OF SCIENCE (HONOURS)  in  THE FACULTY OF SCIENCE (Geological Sciences)  This thesis conforms to the required standard ……………………………………. Supervisor THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2017 © Well-Shen, Lee, 2017 II  Abstract The Dawson Range district in west-central Yukon is host to various important mineral deposits, including several fault and fracture-hosted gold systems, such as the significant 5 Moz Coffee gold deposit. Three gold-bearing hydrothermal vein systems of inferred mid-Cretaceous age (~92-96 ma), sharing the same Au-As-Sb relationship as Coffee are located nearby. A field, petrographic and microthermometric investigation concludes that the Boulevard and Sugar prospects share a common auriferous vein generation with similar ore and gangue minerals. Auriferous veins are strongly controlled by steeply dipping, brittle shear-structures with cataclasite zones as well as disseminated gold-hosting arsenian pyrite replacing mafic minerals and magnetite within the host rock- features also observed at Coffee. Boulevard, Sugar and Longline (a past-producer of gold in the Dawson Range) share similar low salinity (0-8 wt% NaCl), CO2 rich (~0.22 mol%), methane bearing fluids, suggesting a possible co-genetic relationship. All three systems share similar trapping conditions (~300 °C, 1 kbar), however, modeled isochores do not intersect arsenian pyrite stability fields. The Toni Tiger molybdenum occurrence, shares similar fluid characteristics and mineralization age to Boulevard auriferous veins in the absence of a causative pluton. An orogenic molybdenum model is proposed whereby pacification of magnetite buffers allowed for fluid redox fluctuations to precipitate locally sourced molybdenum during the same gold deposition event at Sugar and Boulevard. An epizonal orogenic gold deposit model is proposed for the Dawson Range gold systems, whereby trans-crustal shear zones tap deep-crust gold-bearing metamorphic fluids, advected by residual heat from the cooling Dawson Range batholith (emplaced ~100 Ma).          III  TABLE OF CONTENTS TITLE PAGE……………………………………………………………………………………..i ABSTRACT………………………………………………………………………………...……ii TABLE OF CONTENTS……………………………………………………..………………...iii LIST OF FIGURES……………………………………………………………..……………….v APPENDICES……………………………………………………………………………….…viii ACKNOWLEDGEMENTS……………………………………………………………….……ix Chapter 1 – Introduction, Methods, and Regional Geology 1.1 Introduction……………………………………………………………………………………1 1.2 Methodology………………………………………………………………………………......8 1.3 Tectonic History……………………………………………………………………………...11 Chapter 2 – Petrographic Results 2.1 Sugar Au Prospect……………………………………………………………………………18 2.2 Boulevard Au Prospect & Toni Tiger Au Anomaly…………………………………………32 Chapter 3 – Petrography: Fluid Inclusions 3.1 Fluid Inclusion Assemblage Classification…………………………………………………..47 3.2 Laser Raman Spectroscopy…………………………………………………………………..52 Chapter 4 – Microthermometry  4.1 Sugar Au Prospect……………………………………………………………………………59 4.2 Boulevard Au Prospect………………………………………………………………………60 4.3 Previous Boulevard & Toni Tiger Microthermometry Results……………………………...60 4.4 Comparison and relationship to mineralizing fluids…………………………………………62 4.5 Potential Sources of uncertainty in fluid inclusion P-T-V-X modeling……………………..64   IV  Chapter 5 – Discussion 5.1 Mineralization and Structure: Sugar vs Boulevard vs Coffee……………………………….65 5.2 Gold Transport and Inferred fluid oxidation state…………………………………………...67 5.3 Toni Tiger Molybdenite- Source, Transport, Trap…………………………………………..70 5.4 Paragenesis…………………………………………………………………………………...72 5.5 Longline-Past Au Producer…………………………………………………………………..74 5.6 An “invisible” Heat Source…………………………………………………………………..75 5.7 A mineral deposit model for the Dawson Range gold systems (DRGS)…………………….82 Chapter 6 – Conclusions  6.1 Metallogeny of the Dawson Range gold systems……………………………………………85 6.2 Exploration Implications……………………………………………………………………..86 6.3 Future Work………………………………………………………………………………….88 References Cited………………………………………………………………………………...89                  V   List of Figures Figure 1: Map of plutonic suites near the Yukon-Alaska border………………………………...2 Figure 2: Geologic map of study area……………………………………………………………4 Figure 3: Summary of Dawson Range gold systems……………………………………………..6 Figure 4: Photos from the field area and Coffee Creek…………………………………...……...9  Figure 5: Map of Canadian-Alaskan Cordillera terranes………………………………………..12 Figure 6: Tectonic assemblages forming the pericratonic terranes……………………………..14 Figure 7: U-Pb isotope data displaying the 6 cycles of Yukon-Tanana terrane magmatism……15 Figure 8: Schematic cross section of extensional processes in the Devonian-Mississippian…...16  Figure 9: Geologic Map of the Sugar Au prospect……………………………………………...18 Figure 10: Photos of diorite composition intrusive units at Sugar…………………………...…20 Figure 11: Stereonets showing structural orientations of auriferous veins at Sugar……………21 Figure 12: Core photos and micrographs of vein types at Sugar………………………………..24 Figure 13: Photos of auriferous vein at Sugar…………………………………………………..27 Figure 14: Micrographs of sulphide distribution within auriferous veins at Sugar……………..28 Figure 15: Micrographs of sulphides within auriferous veins at Sugar…………………………29 Figure 16: Sulphide paragenesis of Sugar………………………………………………………30 Figure 17: Photos of cataclasite at Sugar………………………………………………………..31 Figure 18: Micrographs of breccia generations at Sugar………………………………………..32 Figure 19: Paragenesis of veins and alteration at Sugar……………………………………...…33 Figure 20: Geologic map of Boulevard and Toni Tiger……………………………………...…34 Figure 21: Backscatter electron images of arsenic rims at Boulevard………………………….37 VI  Figure 22: Photos of vein generations at Boulevard………………………………………..…..38 Figure 23: Micrographs of sulphides from the auriferous vein generation at Boulevard..……..39 Figure 24: Sulphide paragenesis at Boulevard………………………………………………….40 Figure 25: Micrographs of the cataclasite at Boulevard………………………………………...41 Figure 26: Paragenesis of veins and alteration at Boulevard……………………………………42 Figure 27: Micrographs of calc-silicate alteration at Toni Tiger………………………………..44 Figure 28: Photos of vein generations at Toni Tiger……………………………………………45 Figure 29: Thin section scan image and micrographs of Toni Tiger vein generations………....46 Figure 30: Paragenesis of veins and alteration at Toni Tiger…………………………………...47 Figure 31: Summary of fluid inclusion assemblage types across the systems………………….50 Figure 32: Photos of a typical primary fluid inclusion assemblage in auriferous veins………...51 Figure 33: Photos of a typical pseudosecondary fluid inclusion assemblage…………………...52 Figure 34: Relative Raman shift values for common gaseous species in fluid inclusions…...…53 Figure 35: Laser Raman spectroscopy analysis results for Sugar………………………………56 Figure 36: Laser Raman spectroscopy analysis results for Boulevard……………………….…57 Figure 37: Laser Raman spectroscopy analysis results for Toni Tiger …………………………58 Figure 38: Sources of uncertainty during Raman analysis……………………………………...59 Figure 39: Pressure-Temperature isochore plots of trapping constraints……………………….62 Figure 40: Simplified Pressure-Temperature isochore plots of trapping constraints…………...63 Figure 41: Volume estimation in fluid inclusions……………………………………………....65 Figure 42: Comparison of common features of Dawson Range gold systems………………….68 Figure 43: Comparison of fluid inclusions and gas compositions ……………………………..69 Figure 44: Phase stability diagram of molybdenum……………………………………………72 VII  Figure 45: Diagram illustrating orogenic molybdenum model………………………………....73 Figure 46: Paragenesis of Sugar, Boulevard and Toni Tiger…………………………………...74 Figure 47: Longline trapping conditions superimposed on Sugar & Boulevard………………..75 Figure 48: Sheet model illustration of a batholith with equation of heat flow………………….78 Figure 49: Thermal model for the Dawson Range Batholith without exhumation……………..80 Figure 50: Thermal model for the Dawson Range Batholith with exhumation…………………81 Figure 51: Comparison of deposit models to the Dawson Range gold systems………………...85 Figure 52: Updated summary of Dawson Range gold systems…………………………………88                 VIII  Appendices Note: Appendix C is available in digital format in the back pocket of this thesis.  Appendix A: Sample Database…………………………………...……………………………..96 Appendix B: Fluid Inclusion Microthermometry Data………………...………………………..99 Appendix C: Rock Glossary with relevant hand sample pictures, thin section scans, microphotographs, SEM-EDS data, Raman analysis results and sample database.                   IX  Acknowledgements   The successful completion of this thesis is resultant of a year’s worth of effort in which multiple parties were vital in contributing to my growth as a budding geologist and academic.   I would like to thank Tim Smith, Eric Buitenhuis and Ryan Fetterley of Goldcorp Inc. for generously providing access to drill-core, helicopter support, use of camp facilities and logistical support. I would also like to thank David Gale of Independence Gold Corp. for access to the Toni Tiger prospect. Support from the parties above along with funding from the Mineral Deposit Research Unit’s (MDRU) Yukon-Alaska Metallogeny Project made the field component of this project possible.   I am thankful to Dr. Jim Mortensen, Dr. Lori Kennedy, and Dr. Greg Dipple for being available for many interesting, impromptu discussions. I am also grateful to PhD candidate Kathryn MacWilliam for providing insight on the Coffee deposit and for taking me on as a field assistant during the course of this project and giving me this opportunity to learn. I would like to extend my thanks to the University of British Columbia scanning electron microscope technicians Edith Czetch, Lan Kato and Elisabetta Pani for your guidance and technical support, making the detailed petrographic work in this thesis possible.   I would like to thank the Society of Economic Geologists Canada Foundation and the Northwest Territories and Nunavut Association of Professional Engineers and Geoscientists (NAPEG) Foundation for providing additional scholarship support for this project in the form of the SEG Canada Foundation Undergraduate Scholarship and Finnigan Northern Award for Student Research respectively.   I am truly thankful to my parents and family back home in Malaysia for supporting my passionate pursuance of my goals. I am also grateful to my girlfriend who has been by my side from start to finish.   Most importantly, I am thankful to have been under the constant guidance and tireless support from my supervisor, Dr. Murray Allan. Dr. Allan has given me so many opportunities for learning, challenging and improving myself. I have learnt so much over the past year, and there is so much more for me to learn. I look forward to pushing myself further in pursuance of knowledge in this addictive and exciting field of study that is metallogeny.  1  Chapter 1 – Introduction, Methods, and Regional Geology  1.1 Introduction The Dawson Range stretches from the Moosehorn- Longline prospect near the Yukon-Alaskan border (Yukon MINFILE 115N 024) south-east to the Mt. Nansen epithermal mining camp (Yukon MINFILE 115I 066) near the town of Carmacks (Figure 1). The Dawson Range mineral district is bounded by the Yukon River to the north, the White River to the southwest, and the Nisling River to the south and is underlain by mid-Cretaceous igneous plutons (the Dawson Range batholith) intruding metamorphic rocks of the Yukon-Tanana Terrane (Allan et al., 2013). The Dawson Range mineral district is part of a much larger domain of gold enrichment in the Yukon-Alaska Cordillera known as the Tintina Gold Province. The Dawson Range district is host to various important mineral deposits, including porphyry and epithermal systems such as Casino (Yukon MINFILE 115J 028) and Nucleus-Revenue (Yukon MINFILE 115I 107, 115I 042), deformed intrusion-related copper-gold deposits such as Minto (Yukon MINFILE 115I 022) and Carmacks Copper (Yukon MINFILE 115I 008). The Dawson Range is also host to several fault and fracture-hosted gold systems, including the significant 5 Moz Coffee gold deposit discovered in 2009 (Yukon MINFILE 115J 110, 115J 111).  2   Figure 1: A simplified regional map with the location of the Coffee gold deposit labeled relative to the Yukon-Alaska border, the town of Carmacks, and Mt. Nansen (Prospector Mountain) (Allan et al., 2013).    This study focuses on three hydrothermal vein systems of inferred mid-Cretaceous age that are located in close proximity to Goldcorp’s Coffee deposit: -Sugar (Yukon MINFILE 105J 062), Boulevard (Yukon MINFILE 115J 050) and Toni Tiger (Yukon MINFILE 115J 052) (Figure 2). The Coffee gold deposit is a structurally controlled fault-hosted gold system characterized by steeply dipping structures of variable orientations and cutting host rocks of variable composition. Mineralized structures are strongly oxidized from surface to a depth of 250 m (MacKenzie et al., 2014). Previous studies of Coffee have described hypogene mineralization at Coffee to be controlled by solid solution gold trapped in the arsenian pyrite lattice, deposited as disseminated wall rock replacement or in brecciated structures, independent of host rock lithology (Wainwright et al., 2011; Cruikshank et al., 2011; MacKenzie et al., 2014; Buitenhuis et al., 2014; MacWilliam, pers. Commun. 2016). The absence of significant glaciation in the Dawson Range has preserved 3  an ancient weathering profile, in which meteoric fluids have penetrated through mineralized structures, oxidizing arsenian pyrite, and liberating gold into discrete micro- and nano-particles (Buitenhuis et al., 2014). Oxidized mineralization enables rapid and high-yield gold recoveries up to 95% through cyanide metallurgical column leaching (Buitenhuis et al., 2014).   The Coffee deposit shares its strong Au-As-Sb element association with two drilled gold-bearing vein prospects in the region: The Sugar Au prospect, located 20 km southeast of the Coffee deposit, and the Boulevard Au prospect, located 5 km southwest of the Coffee deposit. The systems above have similar Au-As-Sb element associations, paleo-fluid composition, as well as ore and gangue mineralogy to the Moosehorn (Longline) deposit (92-93 Ma 40Ar/39Ar), a past orogenic gold producer (Yukon MINFILE 115N 024) located at the NW end of the Dawson Range (Fig. 1) (Joyce, 2002). The Toni Tiger Mo occurrence, located 1 km east of Boulevard, shares similar fluid characteristics and 96-95 Ma mineralization age to Boulevard veins (McKenzie et al., 2010), but is distinctive in its metal signature (Mo-Cu-W/As), which further complicates the paleo-fluid evolution of this region. A recent BSc. Hons study of the Sugar prospect (Bartlett, 2016) focussed primarily on geologic mapping and the relative timing of magmatism, alteration, veining, and mineralization. Bartlett interpreted the prospect as an intermediate sulphidation epithermal system with gold mineralization associated with disseminated sulphides proximal to variably sheared quartz-carbonate-sulphide veins hosted by granitoids of the Coffee Creek pluton, and overprinting early-stage calc-sodic and potassic alteration. Sugar was tentatively interpreted to be a deeper-rooted expression of the Coffee gold system (Bartlett et al., 2015). However, vein and alteration studies were limited to two drill holes SGD0001 and SGD0011, largely composed of granitic host rock. The current study reveals more variety and complexity to Sugar’s vein mineralogy, alteration assemblages and sulphide paragenesis, through observations of additional drill core. 4    5  A previous study of the Boulevard gold prospect by McKenzie and co-workers (2013) proposed an orogenic gold model for mineralization based on geological, structural, geochronological and fluid inclusion data. Gold mineralization in the Boulevard prospect is associated with fault zones, simple extensional veins, and vein breccias hosted in quartz-biotite schist and chlorite-biotite schist of the Yukon-Tanana terrane (YTT) along northwest trending structures. In contrast, nearby quartz-molybdenite veins of the Toni Tiger Mo prospect are hosted in diopside-garnet skarn and in leucocratic meta-plutonic rocks of the YTT. McKenzie et al. (2013) concluded based on Re-Os dating of molybdenite at Toni Tiger and Ar-Ar dating of hydrothermal sericite at Boulevard that the age of each system is within error of each other, whereas fluid inclusion analysis indicated both systems formed from similar low-salinity, CO2 rich systems at >280°C and 1100 bar. Because the ca. 95 Ma Re-Os age of molybdenite at Toni Tiger is ~4 m.y. younger than the youngest U-Pb ages obtained for the nearby Coffee Creek pluton, McKenzie et al. (2013) speculated that Toni Tiger could represent an “orogenic molybdenite” prospect analogous to the orogenic gold model at Boulevard. Regardless, significant uncertainty remains regarding the applicability of the orogenic gold model since molybdenite mineralization is more typically associated with hydrothermal systems proximal to a magmatic fluid and metal source.    An improved metallogenic understanding of the similarities and differences between structural controls, vein and sulphide paragenesis, fluid chemistry, and mechanisms of source-transport-trap in these mid-Cretaceous gold bearing hydrothermal systems will potentially aid in exploration for “Coffee”-like systems in the Dawson Range. Furthermore, this study will contribute great strides towards understanding phanerozoic lode gold systems and their classification relative to traditional orogenic gold models.  This study aims to compare the vein mineralogy, paragenenesis, sulphide minerals and fluid inclusion composition of similarly aged mid-Cretaceous quartz-carbonate-sulphide veins in Boulevard, Sugar and Toni Tiger. Petrographic observations of Bartlett (2016) and McKenzie (2014) are reviewed and combined with new petrographic and fluid inclusion data collected from samples collected during the 2016 field season. Petrographic and fluid inclusion data from the three hydrothermal systems of interest are compared and contrasted for similarities and differences to each other as well as to the Coffee deposit. Parallel 6  geochronological studies by Murray Allan will provide new absolute age constraints on the timing of magmatism and hydrothermal alteration in the region, which will benefit interpretations of this vein study.  Figure 3: A summary table comparing the three prospects in this study to the Coffee deposit. Boxes in green display characteristics two or more of these systems share in common, with information known at the beginning of this study.    7  Presented herein are a paragenesis and mineral deposit model for the Sugar, Boulevard and Toni Tiger systems, which will complement ongoing studies of the Coffee gold deposit by PhD Candidate K. MacWilliam and MDRU researchers. This study is funded by the Yukon-Alaska Metallogeny Project of the Mineral Deposit Research Unit at the University of British Columbia, with additional scholarship support from the SEG Canada Foundation and the NAPEG Finnigan Northern Award for Student Research. Generous in-kind support was provided by Goldcorp Inc., including lodging, use of camp facilities, and helicopter support. Access to the Toni Tiger prospect was provided by Independence Gold Corp. Results of this research were presented by the author at the MDRU Yukon-Alaska Metallogeny Project Technical Meeting in September 2016, the 2016 Yukon Geoscience Forum in Whitehorse, the 2017 AMEBC Roundup Conference in Vancouver, the 2017 Cordilleran Tectonic Workshop in Vancouver, and the Geological Survey of Canada Cordilleran Geoscience Discussion Group in March, 2017.  1.2 Methodology  Fieldwork and Sample Collection Twenty-one days were spent at Goldcorp’s Coffee Creek Exploration Camp during the 2016 field season to collect Sugar core samples and surface samples from Independence Gold Corp.’s Toni Tiger prospect. A preliminary analysis and comparison of the veins and alteration present at Sugar, Coffee and Toni Tiger was conducted through core logging, site visits to the Supremo, Latte and Double-Double zones of the Coffee deposit, and helicopter-supported field traverses at Toni Tiger. Additional field data was provided by Goldcorp in the form of assay data, detailed drill core photographs and an oriented drillhole database for Sugar. 36 drill-core samples and six hand samples were made into 26 polished thin sections and 14 thick sections for petrographic and microthermometric analysis.  Significant Au-As bearing intervals encountered in oriented drill holes SGD0001 to SGD0012 were investigated to determine the shear sense of mineralizing veins. Drill core displaying fractured vein margins were investigated for slickenlines indicative of last fault movement on along vein surfaces (Figure 4 (C)). Data of the orientation of paragenetically 8  late carbonate ± quartz veins at Sugar were investigated using measurements from Kaminak’s Sugar drillhole database. The orientation of quartz ± garnet veins and quartz ± molybdenite veins was also measured at the Toni Tiger prospect to improve structural control of veins at Toni Tiger.   Figure 4: (A) Trench in the Double-Double zone of the Coffee gold deposit; (B) Rock exposure near the Toni Tiger prospect; (C) Slickenlines on vein surfaces were measured in oriented core from the Sugar prospect; (D) Core farm at Coffee Creek, where the majority of samples from the Sugar prospect were collected for this study.  Petrography Newly cut thin sections from Sugar and Toni Tiger were complemented with Boulevard and Toni Tiger thin sections from a previous UBC MSc graduate G. McKenzie (McKenzie, 2014). Petrographic analysis was conducted to identify the ore minerals and to determine the mineralogy of mineralizing veins for each hydrothermal system. A Nikon Eclipse E600 POL polarizing microscope was used to observe the thin sections under reflected and transmitted light. Photomicrographs were taken with a Canon EOS Rebel T2i digital camera attached to the microscope. Scanning electron micrcroscopy via the Philips 9  XL30 equipped with a Bruker Quantax 200 energy dispersion X-ray microanalysis system and an XFlash 6010SDD detector (SEM-EDX spot analysis) was used to supplement the petrographic microscope for identifying ore minerals and the various phases of sulphosalts present in the sample suite. Fluid Inclusion Petrography and Microthermometry Observations on fluid inclusion compositions and paragenesis were made from doubly polished, 100 m-thick sections to determine fluid inclusion assemblages suitable for microthermometric analysis. Fluid inclusion assemblages (FIAs), comprising groups of fluid inclusions with uniform phase proportions and a common paragenesis, were identied. These FIAs were classified as primary (formed in growth plane of crystal grains), pseudosecondary (cut growth planes of crystal grains but bound by further crystal growth) or secondary (cut all crystal growth rim generations) (Roedder, 1984; Bodnar, 2013). The shape and size of each fluid inclusion, as well as the phases present (aqueous liquid (L), CO2 liquid (C) and CO2 vapour (V)) at room temperature and their relative volumetric proportions, were recorded. An Olympus petrographic microscope equipped with a Linkham THMSG 600 heating and freezing stage at the University of British Columbia was used to determine the temperature of fluid inclusion phase changes within the functional -197°C to 600°C range of the equipment. The P-T-V-X  behaviour of fluid inclusions were modelled based on the measured temperatures of phase changes, and existingthermodynamic data.   Low Temperature & High Temperature Microthermometric Run Fluid inclusions were cooled to below -100°C until all phases froze. Inclusions were subsequently warmed until a phase change was observed. Ice melting Tm(Ice), clathrate melting Tm(Cla) and CO2 melting Tm(CO2) temperatures were recorded. Above clathrate melting temperature, samples were heated at a rate of 2°C/min until homogenization of carbonic phases Th(LCV→LC) and total homogenization of all phases Th(LC→L) or Th(LV→L) were observed.   The bulk composition of LCV fluid inclusions were estimated using the measured variables Tm(Cla), Th(LCV→LC) and the volume fraction of aqueous fluid after clathrate melting. The partial density of carbonic fluids and salinity of coexisting aqueous phases were 10  estimated from Th(LC→L) and Tm(Cla) respectively with the program Q2 in CLATHRATES (Bakker, 1997), applying equations of state of Dual et al., (1992a, b) and Duschek et al. (1990). Isochores for each FIA were computed using ISOC in the package FLUIDS (Bakker, 2003), with Th(LC→L) and mole fractions of H2O, CO2, and NaCl (outputs from Q2). Equations of State from Bakker (1999) and Bowers and Helgeson (1983) were used.  Fluid Inclusion Laser Raman Spectroscopy  A Horiba Scientific XploRA PLUS Raman Microscope was used to analyse CO2-rich, three-phase (LCV) quartz-hosted fluid inclusions located in auriferous veins at Sugar, Boulevard and Toni Tiger. This method of analysis aims to identify gas species other than CO2 present in the paleofluid. A spectral range of 1000- 4000 cm-1 with an acquisition time of 10 s for each of the 6 accumulation runs was used for this analysis. An objective of 100x magnification with a slit width of 200 µm and a laser wavelength of 532 nm was used throughout the collection period.   1.3  Tectonic History  1.3.1 Regional Geology The study area falls in the Yukon-Tanana Terrane, described by Mortensen (1992) to be one of the largest, tectonically complex terranes of the northern Cordillera. Together with Quesnellia and Stikinia, they make up the pericratonic terranes- Devonian -Permian arcs which formed to the west of the Laurentian continental margin (Colpron et al., 2007).    The Yukon-Tanana Terrane comprises four tectonic assemblages: (1) The Devonian Snowcap assemblage (2) The Devonian to Early Mississippian Finlayson assemblage (3) The mid-Mississippian to Early Permian Klinkit assemblage (4) The Middle to Late Permian Klondike assemblage.   The Snowcap assemblage consists of quartzite, psammitic, pelitic and calc-silicate schists, marble and local amphibolite and ultramafic rocks (Colpron et al., 2006). This assemblage has been metamorphosed to amplibolite facies and subject to polyphase deformation. Many authors have interpreted the Snowcap assemblage to be a rifted 11  continental margin fragment of Laurentia (Templeman-Kluit, 1979; Colpron et al., 2006, 2007; Nelson et al., 2006). Further evidence supporting this interpretation is found in amphibolites in the Glenyon and Wolf Lake areas which display MORB and OIB geochemical signatures (Nelson and Friedman, 2004; Colpron et al., 2006).   Figure 5: Terranes of the Canadian-Alaskan Cordillera with an inset showing terrane groups. Source: Colpron et al. 2007    12   The Finlayson assemblage consists of metavolcanic and metasedimentary rocks deposited unconformably above the Snowcap assemblage. Characteristic lithologies of this assemblage are madic to felsic metavolcanic rocks, carbonaceous pelite, chert, minor quartzite, marble and volcaniclastic rocks coeval with the Grass Lakes and Simpson Range plutonic suites which intrude the Snowcap assemblage below (Colpron et al., 2006). The Finlayson assemblage volcanic rocks have been documented to contain products of both arc and back-arc signatures, interpreted to record the evolution of a Late Devonian to Early Mississippian continental arc to back-arc system (Piercey et al., 2006). Notably, the Finlayson Lake area rocks are host to VMS deposits- Kudz Ze Kayah and Wolverine, where voluminous alkalic to tholeiitic volcanism occurred in a basinal setting (Murphy et al., 2006; Piercey et al., 2006).   The Klinkit assemblage consists of mafic to intermediate calc-alkaline volcaniclastic and volcanic rocks, minor alkali basalt, limestone/marble and basal conglomerate (Colpron et al., 2006). Volcaniclastic rocks are interpreted to be from a primitive arc source, with rare alkali basalts suggesting periodic intra-arc rifting events (Simard et al., 2003). The Klondike assemblage consists of felsic metavolcanic rocks, calc-alkaline, minor mafic metavolcanic rocks and coeval intrusions of the Sulphur Creek suite. Rocks of this assemblage have geochemical signatures of continental arc magmatism (Piercey et al., 2006) and are interpreted to be products of subduction of the Slide Mountain oceanic lithosphere beneath the Yukon-Tanana terrane (Mortensen, 1992; Nelson et al., 2006).    The Slide Mountain assemblage consists of oceanic sedimentary rocks making up deep water strata with basalt flows and diabase sills. Sedimentary strata are mostly well-bedded chert and argillite with a lack of nearby continental sedimentary sources. Thrust panels of ultramafite and gabbro-amphibolite have been interpreted to represent oceanic lower crust and mantle (Colpron et al., 2006). Basalts in this assemblage has N-MORB geochemical signatures (Piercey et al., 2006) and is interpreted to be erupted in a back-arc ocean basin within the Yukon Tanana arc system (Creaser et al., 1997; Nelson et al., 2006).    13   Figure 6: Distinct tectonic assemblages forming the pericratonic terranes. “CO3” highlights large carbonate accumulations in parts of Klinkit assemblage. BAB = back-arc basin. Source: Colpron et al. 2006  1.3.2 Tectonic Evolution of the Yukon Tanana terrane (YTT) The tectonic evolution of the allochtonous pericratonic YTT is constructed on a series of six magmatic cycles defined by Piercey et. al. (2006) and tectonostratigraphic units defined by Colpron et. al. (2006). The Middle-Late Devonian Ecstall Cycle resulted in a west-facing arc and back-arc assemblage (Finlayson assemblage) constructed on the Snowcap assemblage, an older substrate containing continentally derived sedimentary rocks of the north American continental margin, far from the craton. The initial compression event was followed by subduction slab-rollback to the west, driving extension, arc-rifting and syngenetic SEDEX mineralization in rift basins. Eventually this extension resulted in the detachment of the arc complex from the continental margin with the development of the Slide Mountain ocean (Nelson et al., 2006). The Finlayson cycle, Wolverine cycle and Little Salmon cycle represented brief compressional events during this overall extensional period which ended in the Late Mississippian (Nelson et al., 2006). The continued growth of the Slide Mountain ocean resulted in the arc system of the YTT to develop distally from the North American continental margin. Eventually, a reverse in subduction polarity of the YTT arc system 14  resulted in the closure of the Slide Mountain ocean and the resulting accretion of the YTT back to the continental margin (Nelson et al., 2006). This event was coincident with the Middle-Late Permian Klondike cycle, and termed the Klondike orogeny.   Figure 7: U-Pb isotope data summarizing YTT magmatism into 6 cycles in comparison to data from the NACM. Nelson believes the magmatism is associated to specific tectonic events in YTT’s history. The high volume of magmatism in the Wolverine cycle occurring at the Devonian-Mississippian boundary is believed to be related to the rifting of the YTT from the NACM while the late-Permian Klondike cycle is associated with reverse polarity subduction that started the closing of the Slide Mountain Ocean. Source: Piercey et al., 2006. 15   Figure 8: A schematic cross section illustrating the extensional processes in the Devonian Mississippian that combines magmatic information with metallogenic information. Note the main extensional force is interpreted to be caused by rollback of the subducting slab. Source: Nelson et al., 2006. 1.3.3 Post-collisional magmatic events  Convergence in the YTT due to east-dipping subduction resulted in Late Triassic (Taylor Mountain plutonic suite) and Early Jurassic (Aishihik plutonic suite) magmatic pulses (Allan et al., 2013). The lack of preservation for the extrusive equivalents of these early and middle Mesozoic plutons coupled with Early Jurassic 40Ar/39Ar cooling ages suggests significant exhumation of the YTT syn or post-arc development (Hansen et al., 1991; Johnston et al., 1996a; Dusel-Bacon et al., 2002; McCausland et al., 2002; Villeneuve et al., 2003; Berman et al., 2007; Allan et al., 2013; Knight et al., 2013; Nelson et al., 2013). Mihalynuk et al. (1994)’s oroclinal model for the closure of the Slide Mountain Ocean during the Klondike orogeny describes the YTT as the hinge of the orocline, causing regional scale NE-verging folds and SW-dipping thrust faults to accommodate regional shortening (Allan et al., 2013).  NE-dipping subduction at 115 Ma resulted in the formation of the Whitehorse plutonic suite, which includes the Dawson Range batholith and the Coffee Creek granite- abundant near the Coffee deposit and host to gold mineralization at the Kona zone and the Sugar prospect (Buitenhuis et al., 2014; Bartlett et al., 2015). The only preserved extrusive, 16  coeval unit of the Dawson Range batholith is the Mount Nansen Group in the SE limits of the Dawson Range (Allan et al., 2013; Klöcking et al., 2016). The Dawson Range batholith has recorded ages of 107-100 Ma with magmatism ceasing at 98 Ma (Breitsprecher and Mortensen, 2004; Allan et al., 2013), however the Dawson Range batholith has been reported to experience significant syn- to postintrusive deformation on coeval strike slip fault systems such as the Big Creek fault (Johnston, 1999).  The early Late Cretaceous brought about a narrow belt of intrusions (Casino, Sonora Gulch & Nucleus-Revenue porphyry systems), with voluminous magmatic and volcanic activity associated with the Carmacks Group between 72 and 67 Ma (Allan et al., 2013).  The study area falls in gold-dominant fault or fracture hosted mineralization in the central and western Dawson Range. Existing literature interprets the Coffee gold deposit and Boulevard (McKenzie, 2013) to be mid-Cretaceous orogenic gold systems, with Allan et al. (2013) suggesting Coffee to be an epizonal orogenic gold system. Sugar, a gold bearing vein system located 10 km east of Coffee, provides an opportunity to contribute to an emerging metallogenic framework of structurally-hosted gold mineralization in the Dawson Range.   Constraints on the mineralization ages of Coffee and Sugar are pending; however, geological commonalities with the ca. 95 Ma Boulevard and Toni Tiger suggest a similar mid-Creatceous age is likely (M. Allan, pers. comm., 2017)  The juxtaposition of vein-related molybdenite at Toni Tiger in temporal and spatial association with gold at Boulevard leads to several questions regarding the possibility of a magmatic contribution to this mid-Cretaceous mineralizing event in the Dawson Range. This study attempts to add additional petrographic and fluid inclusion constraints on these veins systems, in order to better address these questions.      17  Chapter 2 - Petrographic Results  2.1 Sugar Au Prospect The Sugar prospect is located approximately 20 km east of Boulevard and 20 km south-east of the Coffee deposit area. Up to 12 diamond drillholes were placed approximately 2 km north of Sugar Dome (Figure 9), on a gently north-dipping plateau. The area consists of frost-heaved felsenmeer, moss, lichen and low shrubs at high elevations with outcrop consisting 5% of the land area (Bartlett et al., 2015).   Figure 9: Geologic map of Sugar with drill holes and soil Au anomalies indicated. (Bartlett et al., 2016) 18   2.1.1 Geology Sugar is hosted in syenogranite monzogranite of the Coffee Creek pluton (mKqW), a late phase of the Dawson Range batholith (DRB). The granitoids host pebble to boulder sized xenoliths of metavolcanics rocks interpreted to be derived from Klondike Schist (PK) (Bartlett et al., 2016). To the north of the Coffee Creek suite lie the Late Permian Sulphur Creek plutonic suite orthogneiss of the Yukon-Tanana terrane in inferred fault contact with the DRB. Gold-in-soil anomalies at Sugar cluster in two zones: Sugar East and Sugar West. The soil anomalies cluster around contacts between the granitoids and a diorite dike phase (mKdW) at Sugar East, as well as an andesite dike phase (mKaW) which cuts all other rock units across the prospect.  Detailed core logging in the summer 2016 field season has revealed the presence of a new rock unit, mKdWf – biotite hornblende dolerite (diabase). This unit is a fine-grained, possibly coeval variant of the intermediate composition mKdW (biotite hornblende diorite). It occurs as dikes which cut mKdW and older granitoids, but occurs as xenoliths in the andesite dikes, hence is paragenetically younger than the andesite dikes (mKaW). This unit appears to be compositionally similar to the mKdW unit based on thin section and hand sample comparisons, with the only difference being grain size.  Petrographic observations of the unit are consistent with the composition of mKdW, with poikilitic biotite and hornblende and variable quartz content. Pyrite is also observed to be present in this unit replacing biotite and hornblende, possibly through a later overprinting alteration. Grain size is highly variable in this unit. Chilled margins are evident at the margins of this unit and the diorite wallrock.   19    Figure 10: (LEFT) SGD0007-7.5m biotite hornblende diorite (mKdW) with poikilitic biotite and hornblende in comparison with the newly defined (RIGHT) SGD0007-217.2m biotite hornblende diabase (mKdWf) with alteration from an epidote-K-feldspar vein.  2.1.2 Structure The Sugar prospect is located 5 km south of the west-northwest-striking, dextral strike-slip Coffee Creek fault. A major horse-tailing splay at the fault’s western termination zone imparts the main inferred structural control on the Coffee gold trends (Allan et al., 2013; Sanchez et al., 2014).  Sugar core observations indicate diorite dike orientations are shallow to steeply dipping while andesite dikes dip steeply at east-west and NW orientations. All rock units of Sugar West are cut by NW and north-south trending dextral strike-slip fault structures that converge north of Sugar Dome.  Mineralization at Sugar is controlled by steeply dipping, E-W striking quartz-carbonate-arsenopyrite ± pyrite ± stibnite ± tetrahedrite ± freibergite veins which cut host granitoids as well as the E-W striking, pre-mineral, mid-Cretaceous diorite dikes (mKdW). Brecciation and grain size reduction of ore and gangue minerals as well as low-angle shear fabrics point to cataclastic reworking along brittle shear zones (Bartlett et al., 2015).  Through methods described previously, slickenlines on vein surfaces in oriented drillholes were investigated to determine the direction of latest fault movement. Figure 11 shows two lower-hemisphere, equal-area stereonets indicating all quartz-sulphide vein orientations (LEFT). The dominant vein orientation is approximately 75° dip toward 350°N but with significant scatter, possibly due to misoriented core. Due to the isotropic nature of the granitoid host rocks, the accuracy of this structural data cannot be verified by comparison with a structural reference plane (e.g., host rock foliation). Slickenlines are mainly horizontal and E-W trending, thus indicating pure strike-slip movement. Two of nine slickensided veins 20  have stepped slickenfibres, one of which indicates sinistral shear sense, whereas one yields an apparent dextral strike-slip shear sense. The remaining seven vein surfaces giving ambiguous sense of movement.    The orientation of paragenetically late extensional carbonate ± quartz ± arsenopyrite veins were investigated using the same data query methods. The dominant orientation of these veins is subvertical and striking ~060°N, i.e., 20° anticlockwise of mineralized shear veins. This feature appears to be consistent with sinistral strike-slip shear sense for mineralized structures at Sugar, assuming both the late extensional veins and shear veins formed under the same deformational regime (Allan, 2016).   Figure 11: Lower-hemisphere equal-area stereonet of quartz-carbonate-sulphide shear veins (LEFT) and late carbonate extensional veins (RIGHT) measured in oriented core by Kaminak geologists (great circles are veins, black dots are poles to veins). Shear veins are steeply N-dipping on average. Red dots indicate the direction of slickenlines rarely developed on vein surfaces. Extensional veins are subveritcal and ENE-striking on average. (Allan, 2016).  2.1.3 Veins and alteration: Veins and alteration at Sugar consist of high temperature pre-mineralization alteration and veins followed by shear-hosted auriferous veins and cataclasites. The petrographic descriptions of veins and host rock units that follows are in paragenetic order based on observations of cross cutting relationships seen in the field and in thin sections.  Calc-silicate diopside alteration is manifested as an early, high- temperature skarn feature consisting of an andraditic garnet-diopside assemblage within the granitic host rocks and as endoskarn in immediately adjacent dikes (Bartlett et al., 2015). This alteration is cut by epidote veinlets up to 1 cm in width sometimes occurring with euhedral, pink potassium 21  feldspar within the vein or as overprinting alteration replacing earlier plagioclase in the host rock. This generation is seen in all host rock units although more prominent in the granitic host rocks. Some euhedral grains of cubic pyrite are also seen deposited in the host rock in close vicinity to this veinlet (Figure 12 B). Albite-amphibole veins appear in all host rocks and are manifested as shallowly dipping, multi-directional, thin, fine-grained albite veinlets 0.5 cm in width, with green amphibole occurring as anhedral blebs and as euhedral tabular crystals (Figure 12 D) in the host rock near this vein generation. The albite is sericitized proximal to auriferous veins. Pegmatite veins hosted exclusively in diorite and micro-diorite units are variably dipping and are up to 10 cm in width. This vein generation is composed of texturally distinct quartz- feldspar veins with a myrmekitic texture of wormy quartz replacing plagioclase feldspar originally from the diorite dike host (Figure 12 E & F). This generation is emplaced near locations intruded by the late andesite unit. This myrmekite texture is destructive and overprints host rock by replacing hornblende with chlorite and pre-existing pyrite into chalcopyrite and pyrrhotite. Pegmatitic biotite up to 3.5 cm in grain size is observed. No alteration halo is associated with this generation, although thin sericite-chlorite alteration halos up to 2 cm in width is sometimes observed on one side of the pegmatite vein (Figure 12 E). This alteration may be the result of a subsequent hydrothermal fluid pulse taking advantage of pathways of structural weakness along pegmatite margins. Potassium feldspar in this generation is shown to be weakly deformed, with undulose extinction and twinning and altered to sericite near auriferous veins, hence making this paragenetically earlier than the gold event. Quartz crystals in this generation also exhibit similar undulose extinction, indicating minor strain. Small chlorite veinlets cut these myrmekite veins. Auriferous veins (V3) occur as east-west trending shear veins which dip steeply at 75° to the north (Figure 13) and can be up to 5 cm in width. In drill core and hand sample, this vein generation is hosted in the granite (mKqW), the diorite (mKdW) and occurs near the point of contact between these units and the andesite (mKaW) as well as the newly defined micro-diorite unit (mKdWf). This vein generation is accompanied by a silicification zone and a sericite-chlorite alteration zone up to 3 cm and 15 cm away from the vein. Gold-bearing sulphide mineralization is disseminated within this sericite-chlorite alteration zone 22  rather than within the vein itself. Pseudomorphs of amphibole from the albite-amphibole vein generation as well as diopside from earlier calc-silicate alteration are commonly found to be replaced by sulphide minerals such as arsenopyrite in close proximity to V3 veins. Finally, paragenetically late carbonate-sericite ± quartz ± arsenopyrite ± sphalerite veinlets (V4) manifest as sub-vertical extensional veins with acicular arsenopyrite deposited in the selvages (Figure 13 D). This vein is hairline width and appears throughout all host rocks in swarms. The orientation of these veins is northeast-southwest and steeply dipping to the northwest. This vein also deposits large subhedral grains of sphalerite which overprint earlier generations of arsenopyrite and arsenian pyrite from the V3 vein. A late sericite only hairline width vein swarm crosscuts all vein generations and stratigraphic sequences, although more common near dike contacts. This generation is potentially related to the pervasive chlorite alteration seen across Sugar. Post-mineralization barite has been observed to occur between fractures in space-filling pyrite occurring in the pegmatite veins as a result of the cooling hydrothermal system. 23    Figure 12: Vein types at Sugar. (A) A representative core sample of the epidote veins with pink K-feldspar alteration of granitic host rock (Bartlett et al., 2015). (B) SGWS16-02 An XPL image of the highly birefringent epidote vein overprinting hornblende in diorite host rock. Cubic pyrite is also overprinting the host rock where the epidote vein terminates as well as proximal to the vein. (C) SGWS16-20 Core cut section of representative chlorite-sericite veining in diorite host rock. The chlorite alteration is shown to overprint an earlier albite vein as well as a pegmatite vein. (D) SGWS16-01 XPL image of late sericite veins cutting and overprinting earlier albite alteration with acicular sericite alteration. A tabular amphibole pseudomorph is replaced by arsenopyrite. (E) SGWS16-28 Core cut sample of representative pegmatite vein with acicular biotite in diorite host rock. (F) SGWS16-02 XPL image of myrmekite texture overprinting an early epidote vein. The entire assemblage is then overprinted by dusty sericite alteration from V3.  24  V3 Auriferous Vein and Sulphides In detail, auriferous veins (V3) are internally complex, with multiple phases of gangue and sulphides precipitation, and structural reactivation. These composite veins are typically composed three paragenetically distinct phases (A-C), which are classified below. Phases A, B and C are usually observed in the same vein, and together define V3 veins at Sugar.  A: Prismatic euhedral monomineralic barren quartz  The earliest phase of V3 vein growth is defined by quartz crystals that grow inward from wallrock margins as prismatic, euhedral, space-filling grains up to 0.5 cm in length. This phase of vein growth is extensional, with fluid infilling a gradually opening brittle fracture in the host rock. Quartz distribution may be symmetric, i.e., lining both sides of the wallrock (syntaxial growth), or asymmetric, lining only one side of the wall (ataxial growth).  B: Prismatic-subhedral carbonate veins ± quartz ± arsenopyrite (gold?) Carbonate in this phase of V3 vein growth occurs syntaxially from quartz of phase A.  This generation has also been observed in the absence of phase A. Carbonate is typically dominated by calcite, with distinct deformation twinning and/or undulose extinction. Acicular arsenopyrite is observed within this vein phase, growing adjacent to calcite grain boundaries.  C: Fine-grained Fe-carbonate-quartz-sericite zone ± arsenian pyrite (gold) ± arsenopyrite (gold) ± tetrahedrite-friebergite ± stibnite  Phase C is responsible for the ferroan carbonate-quartz-sericite alteration associated with all auriferous veins at Sugar. Intense quartz-sericite alteration haloes containing disseminated, anhedral to acicular masses of arsenian pyrite and arsenopyrite extend up to 10 cm away from V3 veins. It is unclear whether this zone is purely a replacement alteration zone or a combination of replacement and brecciation. Clasts of host rock such as older quartz grains from the diorite and granitic host rocks of Sugar or the recrystallized quartz schistose host rock at Boulevard can be seen in this zone.  Tetrahedrite-freibergite and stibnite associated with phase C fill open spaces between prismatic quartz grains of phase A. Freibergite reported by Bartlett et. al. (2015) 25  has not been identified by SEM-electron dispersive X-ray spectroscopy spot analysis in this study. The presence of arsenian pyrite was confirmed using SEM-EDS spot analysis. It occurs as anhedral to subhedral crystal grains with a spongy texture, commonly containing inclusions of gangue minerals (Figure 12 E, F) such as Fe-carbonate, sericite and quartz. This arsenian pyrite-pyrite generation is seen overprinting early acicular arsenopyrite (Figure 12 E) and in turn is replaced by cubic-rhombic arsenopyrite. Cubic-rhombic arsenopyrite commonly occurs with a spongy core, indicating multiple growth generations of pyrite and arsenian pyrite.  No native gold has been observed at Sugar. However, gold concentrations from assay data correlate strongly with the presence of the V3 vein generation in drill core. This vein generation hosts blebby anhedral arsenian pyrite riming and growing adjacent to early pyrite from the host rock. Arsenian pyrite has also been shown to be the main gold carrying sulphide at the nearby Coffee deposit (Wainwright et al., 2010; MacKenzie et al., 2013; Buitenhuis et al., 2015). SEM-EDS element mapping has revealed a significant amount of gold within these arsenian pyrite grains, however, unlike Coffee, the arsenian pyrite at Sugar does not display zoning. 26   Figure 13: V3 Auriferous vein. (A) SGD0007-122.8m Core cut sample of a representative V3 quartz-carbonate-sulphide composite vein at Sugar. Intense silicification and sericitization occurs near this vein in the diorite host rock. (B) SGD0007-122.8m XPL thin section scan of the V3 vein showing the barren prismatic quartz generation with a fine-grained carbonate infill. (C) SGD0007-292.1 XPL image of the fine-grained Fe-carbonate-sericite zone displaying disseminated arsenopyrite. (D) SGD0007-122.8 Reflected light image of cubic arsenopyrite in the carbonate zone of a V3 vein. (E) SGWS16-16 Backscattered electron image of spongy anhedral-subhedral arsenian pyrite (FeS2±As) overprinting early euhedral acicular arsenopyrite (FeAsS). (F) SGWS16-24 Cubic-rhombic arsenopyrite is seen with spongy cores and relatively new growth rims showing to be replacing and growing on top of earlier arsenian pyrite.     27   Figure 14:  SGWS16-25 Reflected, XPL and PPL images of sulphide mineral distribution in a V3 vein. Stibnite-tetrahedrite sulfosalts are exclusively precipitated as space-filling sulphides in the barren quartz generation while arsenopyrite and arsenian pyrite are disseminated along shear zones in the fine-grained carbonate zones. Later carbonate veins exploiting pre-existing areas of weakness overprint the areas with arsenopyrite and sphalerite. 28   Figure 15: Reflected ore petrography of sulphides from the V3 Auriferous vein SGD0007-122.8. (A) & (B) PPL and XPL image of tetrahedrite-stibnite sulfosalt occurring as space-filling sulphides strictly in the prismatic quartz zone. (C) & (D) PPL and XPL images of anhedral, late sphalerite overprinting earlier cubic arsenopyrite in the carbonate zone. (E) & (F) PPL and XPL images of acicular arsenopyrite occurring in the carbonate zone.     29   Figure 16: Sulphide paragenesis of the Sugar Au prospect based on petrographic observations of cross cutting, overprinting and replacement relationships.  2.1.4 Breciation and shear structures: Cataclasite zones consisting polyphase brecciation, grain size reduction and shear fabrics have been observed within and along the margins of veins from the Sugar prospect. Up to three separate brecciation events have been documented in this study, classified paragenetically based on cross-cutting relationships and mineralogy.   Figure 17: A series of images displaying brecciation zones observed at Sugar SGWS16-13. (A) Core cut sample of a sheared V3 vein adjacent to a polyphase breccia zone. (B) A PPL thin section scan of the same sample with the area of interest being within the white rectangle. (C) A PPL image of the various brecciation zones observed in the sample with crosscutting relationships displayed.    30  B1:  The first cataclastic event (B1) is recorded by clasts of quartz, possibly from pre-existing vein quartz and/or quartz from granitic host rocks. This zone displays the most intense oxide staining out of the 3 defined zones. Closer observation shows that the intense dark brown color may be limonite resulting from weathering of a high concentration of disseminated sulphide grains (mostly pyrite) and ferroan carbonate. B1 is composed of small (<10 m) sub-rounded quartz clasts (5-10%) and a matrix (90%) of carbonate and disseminated sulphides (pyrite?). Euhedral cubic pyrite grains only a few microns across have been observed in the matrix of this breccia, indicating that sulphide precipitation outlasted formation of B1 cataclasite.  B2:  A second cataclastic  shear band (B2) ~100 microns in width consists of subangular to sub-rounded quartz clasts supported in a carbonate and disseminated sulphide matrix. This generation contains clasts of B1 cataclasite, and hence is paragenetically later. B2 has a higher abundance of clasts (20%) than B1 and also has a slightly lighter oxidation staining intensity.  B3:  A third brittle-cataclastic shear band (B3) ~100 micron in width contains subangular to subrounded quartz and carbonate clasts in a carbonate matrix with rare disseminated sulphide. B3 has an even higher abundance of clasts (30%) than B2 and has the lowest intensity of oxidation staining among the three events. This is possibly due to the lower proportion of pyrite within this zone. This generation contains clasts of both B1 and B2 cataclasite, as well as carbonate from V3, and hence is paragenetically latest of the three cataclastic events, and post-dates all V3-related mineral precipitation events.  31   32   Figure 19: A paragenesis of veins and alteration at Sugar. High temperature calc-silicate alteration and pegmatite veining is highlighted in green and is potentially related to dike emplacement. V3 veining events are highlighted in orange and is believed to be related to the brecciation event resultant of changes in differential stress that potentially produced the diorite dikes.   2.2 Boulevard Au Prospect & Toni Tiger Mo Anomaly Boulevard and Toni Tiger are located in an upland plateau within the Dawson Range called Independence Creek. This area is 140 km south of Dawson and 10 km southwest of the Coffee gold deposit. Topology in the area consist of rolling hills with low shrubs, moss and lichen in the same unglaciated, outcrop-poor terrain as Sugar and Coffee.  2.2.1 Geology Independence Gold Corp. claims full ownership to the Boulevard and Toni Tiger properties, which are sandwiched in between the Dawson Range Batholith (100 Ma) to the south and the Coffee Creek pluton (99.4 Ma) to the north. Boulevard host rocks are northwest trending thrusted sheets of Late Permian Klondike assemblage rocks from he Yukon-Tanana Terrane. Gold mineralization at the Boulevard Sunset trend is a northwest trending, 4 km long stretch of Au-As-Sb soil anomalies consisting of sheeted quartz-33  carbonate-sulphide shear veins. Toni Tiger is approximately 2 km east of the Boulevard trends. It is hosted in a resistive, outcrop-forming knob covering a forty-square kilometer area of calc-silicate altered biotite-schist possibly with a calcareous protolith, as well as an adjacent competent magnetite bearing meta-aplite. Quartz-garnet veins and quartz molybdenite veins crosscut both host rocks in northeast trending structures.   Figure 20: A geologic map displaying Boulevard and Toni Tiger locations as well as the dated age of various rock units and mineralization (McKenzie et al., 2014).  34  2.2.2 Veins and Alteration at the Boulevard Au Prospect Veins occur in both pre-syn and post-metamorphic fabric development, with auriferous veins comprising of the youngest brittle fracturing event. V1 barren quartz veins up to 2 cm wide occur as boudinaged folded and rootless hinges in pre-mineralization ductile folding events. This vein generation is monomineralic with subhedral to euhedral grains displaying undulose extinction, deformation kinks and grain recrystallization. This generation is devoid of sulphide minerals and concordant with the metamorphic fabric, therefore was likely formed before or during ductile deformation of the Boulevard host rocks. V2 Quartz-chlorite (diopside?) ± chalcopyrite ± pyrrhotite veins occurs up to 5 cm wide, semi-concordant to crosscutting the metamorphic fabric and folding and accompanied with an acicular chlorite halo which is interpreted to be pseudomorphs of early high temperature diopside alteration. This recrystallized and deformed (Figure 22 B & D) vein generation occurs with space-filling anhedral pyrrhotite and chalcopyrite resultant from the metasomatism of early pyrite within a chlorite halo.  V3 Auriferous quartz-carbonate-sulphide veins occur up to 2 cm in width, is northwest-southeast striking and shallowly dipping 30° to the southwest. This vein generation crosscuts previous vein generations and all metamorphic fabrics. Furthermore, this vein generation is relatively undeformed compared to earlier vein generations and lacks the undulose extinction seen in V1 and V2, signifying it’s a post deformational feature. This vein generation is also associated with a ferroan carbonate-sericite alteration halo and silicification zone 10 cm and 5 cm thick respectively. Sulphide mineralization is disseminated within the carbonate-sericite alteration zone (Figure 22 C, E, F). Paragenetically late V4 Chalcedonic quartz ± carbonate ± pyrite veins are cubic pyrite bearing colloform banded quartz-carbonate vein up to 5 cm. This vein occurs in all rock types and is seen cutting and offsetting V3 veins. Finally, hairline width Fe-carbonate veins in multidirectional orientations crosscut all vein generations, metamorphic fabrics and lithology. V3 Auriferous Vein and Sulphides This vein generation consists of composite veins with multiple phases of gangue, sulphides and structural reactivation. Phases A, B and C are usually observed in the same 35  vein and together defines V3. Phase D is additionally observed at Boulevard in the absence of phase C.  A: Prismatic euhedral monomineralic barren quartz  The earliest phase of V3 vein growth is defined by quartz crystals in this phase growing syntaxially as prismatic, euhedral, space-filling quartz grains up to 0.5 cm in length. This generation can be symmetric, lining both sides of the wallrock (syntaxial) or ataxially, lining only one side of the wall.  B: Prismatic-subhedral carbonate veins ± quartz ± arsenopyrite (gold?) ± native gold Carbonate in this phase of V3 vein growth occurs syntaxially from phase A.  This phase has also been observed in the absence of phase A. Carbonate is typically dominated by calcite, with distinct deformation twinning and undulose extinction. Acicular arsenopyrite is observed within this vein phase growing adjacent to calcite grain boundaries.  C: Fine-grained carbonate-quartz zone ± arsenian pyrite (gold) ± arsenopyrite ± native gold± tetrahedrite-friebergite ± stibnite This phase contains clasts of biotite-quartz schist host rock and many mica clasts remnant of the host rock. The clasts of recrystallized quartz grains are still well-aligned with respect to each other in some localities. This zone is associated with cataclastic reworking (See Brecciation and Shear Structures), forming massive, space-filling and overprinting arsenian pyrite flooding across pre-existing sulphides in the cataclastie. A sericification halo consisting fine-grained carbonate-sericite-quartz alteration emanates from the margins of this vein and replaces pre-existing pyrite, mafic amphiboles and biotite in the host rock with gold-bearing arsenian pyrite, tetrahedrite, stibnite and minor arsenopyrite. Native gold has been observed at Boulevard within the V3 vein generation (McKenzie, 2013). Gold concentrations from assay data correlate strongly with the presence of the V3 vein generation in drill core. D: Prismatic barren calcite veins with euhedral calcite infill   This generation occurs as part of the came composite vein structure and is exclusive to generation C. 36   Figure 21: BV22-73.23m SEM-EDS element mapping results for arsenian pyrite at Boulevard demonstrating the arsenic rich rimming observed frequently in the breccia zone arsenic bearing phases. (C) Background arsenic is resultant of interference from Mg-carbonates in the groundmass. 37   Figure 22: A, B & C are core-cut samples of V1, V2 and V3 respectively, with V3 cutting V2 in C. (D) BV22-17.37 An XPL micrograph of a V2 vein with acicular chlorite riming recrystallized and deformed quartz. (E) BV22-73.23 An extensional V3 vein displaying a composite vein texture with different generations of quartz-carbonate veining forming as the vein gradually widens. (F) BV22-73.32 Carbonate-sericite-quartz zone with disseminated arsenian pyrite from the area within the white square in (E).    38   Figure 23: (A) BV27-63.42 A reflected light image showing euhedral cubic pyrite rimmed and gradually replaced by anhedral pyrrhotite and chalcopyrite. (B) BV26-51.54 Subhedral spongy arsenian pyrite observed along shear planes interpreted to be syn to post-deformational replacement of mafic minerals. (C) BV22-73.23 Reflected light image of massive space-filling pyrite. Bireflectance in the crystal structure may be due to variations in arsenic content in the pyrite crystals. (D) Back-scatter electron image of spongy textured subhedral arsenian pyrite with similar mineral inclusions to that seen at Sugar. (E) Arsenopyrite seen to be rimmed by arsenian pyrite. The sulphide paragenesis for Boulevard is unclear as there is evidently more variable sulphide precipitation across different sample suites. (F) BV22-73.23 Acicular arsenopyrite shown in reflected light to be growing in the grain boundaries of carbonate grains in a V4 vein.    39   Figure 24: Sulphide paragenesis of the Boulevard Au prospect based on petrographic observations of cross cutting, overprinting and replacement relationships.  2.2.3 Brecciation and shear structures The cataclasite at Boulevard contains variable amounts of quartz clasts (10-20%) from V1 veins and the metasedimentary host rocks with 50-60% of the matrix being massive pyrite with variable amounts of arsenic. Other matrix components include ferroan carbonate and limonite. Backscatter electron images of these zones show pyrite replacement of many earlier generations of sulphides with arsenic rich rims characteristic of the gold-bearing pyrite phases at Coffee.  Distinction between breccia generations at Boulevard is challenging due to the overprinting pyrite flooding event which obscures traces of earlier overprinting relationships. However, V3 veins have been shown to brecciate these cataclasites in further shearing events, hence proving the polyphase nature of these shearing events. No native gold was observed in this study; however, Independence Gold Corp. has observed native gold within the quartzites in the Sunrise trends (Gale pers. comm. 2016). 40   Figure 25: (A) BV22-73.23 An XPL micrograph image of the Fe-carbonate-sericite-quartz sulphide zone for comparison. Clasts of recrystallized quartz and muscovite are from the metamorphic host rocks of Boulevard. It is unclear whether this is a zone of brecciation or heavy alteration where only resistant quartz clasts have remained. (B) BV22-73.23 An XPL micrograph of the cataclasite observed at Boulevard, which contains clasts of V1 suspended in a massive pyrite infill. (C) BV22-73.23 An XPL micrograph showing a clast of sulphide breccia-fill material broken off and rimmed by carbonate grains from V3 veining events. (D) BV22-73.23 Prismatic carbonate grains with massive calcite infill riming a sulphide rich cataclasite zone at Boulevard which contains clasts of V1 vein material and the metamorphic host rock.   41   Figure 26: A paragenesis of veins and alteration at Boulevard. High temperature alteration and veining is highlighted in green. V3 veining events are highlighted in orange and is believed to be related to the brecciation event resultant of changes in differential stress.  2.2.4 Veins and Alteration in the Toni Tiger Calc-silicate assemblage 100 m south of the main Toni Tiger Mo occurrence, additional quartz-garnet-molybdenite veins are hosted by calc-silicate altered metamorphic rocks. Early, pre-skarning hydrothermal biotite alteration is overprinted by the diopside-garnet calc-silicate assemblage. Three generations of quartz-dominant veins cross-cut this unit. Calc-silicate alteration is focused around early fractures and early barren quartz veins (Figure 28 A). This high temperature skarn alteration is progressive and changing from proximal to distal ranges. The mineralogical order from proximal to distal is listed below.  A: Clinopyroxene (Diopside)-albite ± hydrothermal garnet ± carbonate  Anhedral, blebby diopside and fine-grained euhedral, twinned albite is intergrown and overprints the host rock in an alteration zone up to 2 mm wide (Figure 28, 29). In general, anhedral hydrothermal garnet and space-filling calcite is observed to occur in between diopside and albite grains. This zone is associated with early fractures and barren quartz veins.   42  B: Ca-amphibole (Actinolite) ± chlorite ± pyrite ± pyrrhotite ± chalcopyrite ± scheelite Euhedral acicular Actinolite-chlorite occurs within a narrow 1mm wide alteration zone behind the diopside-albite alteration (Figure 28, 29). Primary, hydrothermal chlorite as well as late secondary chlorite (replacing actinolite) are both present in this zone. Anhedral pyrrhotite and chalcopyrite occur together as space-filling sulphides. These sulphides also contain pyrite inclusions. Scheelite is present as subhedral grains up to 300 microns in length disseminated among the calc-silicate minerals. Magnetite grains present in the host rock are rimmed by an alteration of Fe-oxide, titanite and ilmenite.   2.2.5 Vein Paragenesis and Molybdenite NW trending and steeply dipping 70° southwest early monomineralic barren quartz veins occur within the diopside-garnet skarn (Figure 27). This syn to post-skarning vein generation is up to 4 cm wide and its association with the pre-mineralization calc-silicate alteration is uncertain. This vein generation tends to form between competent recrystallized quartz and schistose sheet silicate fabrics. A weak, green alteration halo is seen accompanying these veins consisting of acitnolite, chlorite and epidote. The barren quartz veins are cut by planar, cloudy massive quartz-garnet veins 2 cm -10 cm wide in the skarn host rock and up to 1 m wide in the leucogranite host rock (Figure 29). This generation consists of large grains of subhedral to euhedral quartz with subhedral hydrothermal garnet form with slight deformation indicators. An alteration halo is not observed with this vein generation. Diopside and actinolite-chlorite clasts can be seen within some of these veins in the skarn host rock. In the leaucogranite host, this vein generation displays syntaxial, vuggy growth.   43   Figure 27: (A) TTWS16-01C XPL image of quartz-garnet vein crosscutting barren quartz vein and skarn alteration. (B) TTWS16-01D XPL image of quartz-garnet vein crosscutting earlier diopside-albite alteration, evidenced by this vein sandwiched between the same diopside grain, with clasts of diopside within the vein quartz. (C) & (D): TTWS16-02 Anhedral-subhedral garnet-diopside-actinolite-calcite alteration resultant of the early pre-mineralization skarning event. (E) & (F): TTWS16-02 Subhedral-euhedral garnet intergrown with diopside and albite within the same alteration zone.  Quartz ± molybdenite veins occur as hairline-width (single grain width) stringers up to 1 cm in length which have a steeply dipping NW orientation in the skarn host rock (Figure 29 C, D). This generation occurs in pre-existing cracks and veins, thus appearing to have a spatial association but no genetic association to the high temperature calc-silicate alteration 44  or the quartz-garnet veins. This vein generation cross-cuts the quartz-garnet vein at a high angle. No alteration halo is observed with this vein, however, acicular molybdenite can be seen disseminated in close vicinity to the vein within the calc-silicate host rock. Acicular, massive molybdenite blobs up to 2 cm in diameter symmetrically line the rims of the quartz-garnet vein close to the wallrock in the in the leucogranite host rock. No other vein generation cuts this meta-aplitic host, with the only alteration observed being brown, limonite staining.   Figure 28: (A) TTWS16-01: Crosscutting relationships of vein generations in calc-silicate altered host rock. Barren early quartz veins with a green actinolite-chlorite-epidote alterarion halo and the fractures cutting them are associated with calc-silicate alteration. These features are further cut by thicker quartz ± garnet veins. Later fractures (no alteration halo) cut these veins and provide pathways for limonite staining possibly from meteoric weathering. (B) Hand sample TTWS16-03 image of a quartz-garnet vein in a calc-silicate host with subhedral garnet growing on the rims. (C) Hand sample TTWS16-04 image of a quartz-molybdenite vein from the leucogranite host rock with molybdenite growing symmetrically on both sides of the vein. 45   Figure 29: (A) XPL image of a quartz-garnet vein cutting a calc-silicate altered zone. Alteration zones are distinguishable based on mineralogy: Diopside-albite> Actinolite-chlorite> Biotite. (B) XPL image of a calc-silicate host with diopside alteration visible on the top-left in trend with early barren quartz veins cut by massive quartz-garnet veins. The quartz garnet veins are then steeply cut by a quartz-molybdenite veinlet as indicated. (C) & (D): TTWS16-01B PPL and XPL images of a quartz-molybdenite vein. Accicular molybdenite appears to be precipitated at the terminus of this single-grain width vein.   46   Figure 30: Paragenesis for Toni Tiger system. Calc-silicate alteration is marked in green. The intrusion of the Coffee Creek plutonic suite is also marked on this paragenesis as evidence of hornfelsing can be seen in purple biotite scattered in float material near Toni Tiger.            47  Chapter 3 - Petrography: Fluid inclusions  3.1 Fluid Inclusion Assemblage Classification Room temperature observations of fluid inclusion assemblages (FIA) in quartz indicate four main compositional groups. Fluid inclusion assemblages are classified based on compositional differences divided into liquid aqueous phases (L), usually consisting water and dissolved salt, vapour phases (V) consisting Carbon dioxide, trace methane and/ or water vapour, and clathrate (C) consisting liquid carbon dioxide.   Type 1: CO2 rich, 3-phase inclusions LVC (0.5)  These FIAs correlate with primary growth zones on quartz grains as well as pseudosecondary fractures. Individual inclusions are between 10- 15 microns in length. Anhedral large secondary fluid inclusions are also present and can be up to 30 microns in length. Phases present in these inclusions at room temperature include an outer domain of low-salinity aqueous fluid L(aq), an intermediate zone of liquid CO2, and an inner of CO2-dominant gas bubble with trace methane as indicated by laser Raman spectroscopy carried out in this study.  These inclusions are present in Sugar V3 and V4 mineralized quartz veins, Boulevard V3 mineralized quartz veins, as well as in Toni Tiger garnet crystals and quartz-molybdenite veins. Psuedosecondary and secondary FIAs are parallel to cataclastic shear fabrics related to mineralization, inferred from fracture planes parallel to vein-scale shearing fabrics and fractures seen in thin section.  Type 2: Aqueous 2-phase inclusions LV (0.6-0.7)    Elongate primary and anhedral pseudosecondary inclusions up to 8 microns in length. These FIAs are observed riming crystal growth edges, as well as cutting growth planes within quartz crystals.  These FIA are observed exclusively in wormy quartz grains within the myrmekite texture at Sugar as well as the quartz veins at Toni Tiger. Raman analysis on these fluid inclusions from Sugar indicate CO2 in the vapour phase. These fluid compositions are interpreted to be the pre-mineralization high temperature fluid related to the formation of these myrmekite textures.  48    Type 3: Aqueous 2 phase quartz inclusions LV (0.8-0.9)  Secondary anhedral aqueous inclusions up to 10 microns in legth which occur throughout the Sugar pegmatite veins as well as in the mineralizing veins in small amounts. These FIA are double phase fluid inclusions at room temperature and are interpreted to be post-veining, post-mineralizing fluid present during subsequent deformation or exhumation events.  Type 4?: Aqueous L-only inclusions Euhedral and elongate Liquid-only inclusions up to 5 microns in length observed in quartz grains and carbonate grains within V3 and quartz grains in pegmatite veins in small, localized areas near sulphides or in between quartz grain boundaries. These FIAs were most possibly subject to post-formation modification and stresses, hence were not investigated further.   Figure 31 displays a tally of the FI Types observed in this study in terms of abundance and vein type. Due to time constraints, fluid inclusion analysis was focused on Type 1 inclusions, which are found in all mineralizing veins across the three hydrothermal systems in question. Analysis methods performed were Raman spectroscopy on Sugar, Boulevard and Toni Tiger and microthermometry on Sugar and Boulevard V3 vein quartz. 49   Figure 31: A table summarizing fluid inclusion assemblage types observed in this study in terms of abundance in association with vein types. Type 1 inclusions are clearly seen in high abundance across all three hydrothermal systems and suggest a possible common fluid chemistry and similar trapping conditions within mineralizing vein quartz. Type 2 inclusions are almost exclusive to high temperature pre-mineralization pegmatite veins at Sugar and are possibly of a high temperature fluid early in the hydrothermal system’s history.   50   Figure 32: (A)A 100 micron-thick section scan of SGWS16-22, a sample of a typical V3 mineralizing vein with a late extensional carbonate vein cutting across at labels 6, 7 and 8. Areas where microthermometry were carried out are labeled in the red squares. (B) A micrograph of a primary Type 1 inclusion in the V3 vein. (C) An image of the quartz crystal of interest in B.  51    Figure 33: (A) 100 micron- thick section scan of a typical pegmatite vein with myrmekite texture (SGWS16-19) with areas of interest highlighted in the red squares. (B) A micrograph of two-phase pseudosecondary Type 2 inclusions on the edge of a crystal indicated in (C).   52  3.2 Laser Raman Spectroscopy  Laser Raman spectroscopy was carried out to identify additional gas species besides carbon dioxide within Type 1 aqueous-carbonic fluid inclusions. Determining the gas composition present in the paleofluid would reveal more information on ore fluid composition at Sugar, Boulevard and Toni Tiger when paired with microthermometry results. A consistent high resonance peak at ~2450 cm-1 is resultant of interference from the glass slides and hence obscured any ability to distinguish a nitrogen gas signature from the noise. Furthermore, the absence of a standard for comparison allows for only qualitative results from this study as compositional abundance of any trace gas measured cannot be estimated. Raman peaks were compared with peak values compiled and published by Frezzotti et al. (2011) (Figure 34).     53  3.1.1 Sugar Au Prospect Raman spectroscopy was carried out on 14 Type 1 and Type 2 inclusions within the V3 mineralizing vein. All three trials on Type 1 inclusions returned the same results (Figure 35), with the vapour bubble yielding a strong CO2 peak and a weak CH4 peak. The liquid carbon dioxide phase displayed a weak CO2 signature and a weak liquid water signature. The L (aqueous) phase was no different from background quartz signatures (Possibly obscured by background noise), and hence no inferences can be made about the composition of the L phase. 3 of 5 trials performed on Type 2 inclusions within the V3 mineralizing vein have detected a weak CO2 signature, in the vapour phase, indicating the presence of trace CO2 in these dominantly aqueous fluid inclusions.  A high level of background interference was recorded for Sugar samples, causing a high degree of scatter from the laser, rendering 5 of the 14 trials useless. A significant increase in the exposure time was needed to collect interpretable spectra.  3.1.2 Boulevard Au Prospect Six Type 1 inclusions were investigated within the V3 mineralized vein. Two trials were mostly obscured by noise but the remaining four trials showed identical spectra, with the gaseous phase displaying strong CO2 signatures and a weak CH4 signature (Figure 36). The liquid carbon dioxide phase displayed a strong CO2 signature and a weak methane signature. The L (aqueous) phase displayed a strong liquid water signature and a very weak carbon dioxide signature, possibly from interference from the C phase since dissolved bicarbonate ions in the aqueous fluid has a different Raman shift compared to molecular CO2.  The Boulevard and Toni Tiger results were less affected by background interference and hence quality results could be obtained with mostly carbon dioxide and methane partitioned in the gaseous phase of the inclusion while a strong water signature dominates in the aqueous phase.     54  3.1.3 Toni Tiger Molybdenite Anomaly Five Type 1 inclusions in close vicinity to molybdenite grains were investigated within the quartz-molybdenite vein. Four of the five trials showed consistent results (Figure 37) with the gaseous phase displaying strong CO2 signatures and a weak CH4 signature. The liquid carbon dioxide phase and the L (aqueous) phase displayed a strong liquid water signature and a very weak carbon dioxide signature.  3.1.4 Raman Analysis Conclusions: Although slight variations were observed in Raman analysis, it can be concluded that all three hydrothermal systems have similar CO2 and minor CH4 compositions within Type 1 inclusions. Type 2 inclusions from Sugar were also shown to contain trace carbon dioxide gas early in the fluid evolution of Sugar. Paleofluids for these systems were therefore carbon dioxide dominant with trace methane.  Several questions arising from the results of this analysis include: In comparing pre-mineralization Type 2 inclusions to Type 1 inclusions, what caused the sudden CO2 enrichment of the system? The presence of methane gas in the fluids indicate a reduced system. However, Toni Tiger, Boulevard and Sugar host rocks are magnetite rich.  Molybdenum is preferentially transported in fluids with higher oxygen fugacity, hence what is the transport mechanism for molybdenum in a reduced system?  The questions above will be discussed in a later section.    55   Figure 35: A summary of Raman analysis results for Sugar with images of a typical V3 quartz grain and a typical Type 1 inclusion. Results indicate the gaseous phase contains carbon dioxide and trace methane.  56   Figure 36: A summary of Raman analysis results for Boulevard with images of a typical V3 quartz grain and a typical Type 1 inclusion. Results indicate the gaseous phase contains carbon dioxide and trace methane while the aqueous phase contains water and trace carbon dioxide.  57   Figure 37: A summary of Raman analysis results for Toni Tiger with images of a typical V3 quartz grain and a typical Type 1 inclusion. Results indicate the gaseous phase contains carbon dioxide and trace methane while the aqueous phase contains water and trace carbon dioxide.    58  3.1.5 Potential sources of uncertainty in Raman analysis Variability in the measured results during Raman analysis is largely due to equipment sensitivity and random error. Two major sources of uncertainty for measuring the liquid carbon dioxide phase are summarized in Figure 38. Focal plane uncertainty stems from incorrect focus of the laser beam with respect to the three-dimensional orientation of a fluid inclusion. As seen below, the “Top View” is the two-dimensional viewpoint of the user. The focal plane of the laser can be easily misfocused on the wrong phase (red crosses), and thus generating signatures characteristic of that phase such as methane gas partitioning in a “liquid carbon dioxide” phase.   Another source of error stems from pseudo-Brownian motion of the vapour phase within the fluid inclusion. At room temperature, the vapour phase of CO2 rich fluid inclusions undergoes pseudo-Brownian motion arguably due to electrostatic interaction between particles (Bodnar, 2003). This random motion of the vapour phase makes it hard to focus on a point within the confines of the CO2 liquid phase. As the temperature within the fluid inclusion rises slightly during the use of the laser, pseudobrownian motion becomes more frequent and rapid, thus the likelihood of the laser beam intersecting the vapour phase increases.    Figure 38: Sources of uncertainty during Raman analysis. Red and green crosses represent focal points of the laser beam while t1 and t2 represent separate instances in time during data acquisition.   59  Chapter 4 – Microthermometry  Microthermometry was conducted to compare and understand the paleofluid composition and possibly understand mineralizing conditions for all three hydrothermal systems. Due to time constraints, only Type 1 inclusions from Sugar and Boulevard were analysed using this method. Results from this analysis were compared to existing reconnaissance microthermometry data by McKenzie (2014), which includes some data for Type 1 fluid inclusions in Toni Tiger quartz and garnet crystals. Results are tabulated in Figure 39.  Some assumptions were made for modeling isochores of the inclusions: 1. The aqueous component of fluid inclusions can be modeled in the simple H2O-NaCl system (i.e., concentrations of additional cations and anions are negligible);  2. Since the proportion of methane gas could not be quantified during Raman analysis, the non-aquous phase was modelled as 100% CO2.   4.1 Sugar Au Prospect Quartz hosted Type 1 inclusions were cooled to -98 °C to -102 °C, where complete freezing was observed. Initial melting occurred between -57 °C to -60 °C, close to the triple point of CO2 (-56.6 °C). These temperatures indicate this system is a carbon dioxide-rich system, with trace methane gas as indicated by the depressed initial melting point. Clathrate melting temperatures were consistently in the range of 8.8 °C to 9.9 °C. This depression of the clathrate melting point (9.8 °C in a pure H2O-CO2 system) suggests the presence of minor amounts of NaCl within the aqueous fluid. The carbonic liquid and gas phases in Type 1 inclusions homogenized into a single carbonic phase via bubble point transition (Tbub(LCV→LC)) in the temperature range of 28.7 °C to 31.5 °C (CO2 critical point 31.1°C) Final homogenization of the aqueous and carbonic phases (Th(LC→L)) ranged from 280 °C to 343 °C.  Hydrothermal fluids within V3 veins at Sugar are best approximated by the three-component H2O-CO2-NaCl system, and have a modeled bulk density of 0.73 to 0.81 g/cm3 and composition of 22 to 30 mol% CO2 and ~0.4 to 1 wt% NaCl. Figure 40 shows fluids at 60  Sugar were trapped in quartz as a single-phase fluid at conditions above 300 °C and 950 bar. These minimum trapping conditions correspond to a minimum depth of 3.4 km assuming lithostatic pressures (density of 2800 kg/m3) and 10.8 km assuming hydrostatic pressures (density of 1000 kg/m3).  4.2 Boulevard Au Prospect Quartz-hosted Type 1 inclusions tested in this experiment were cooled to between -99 °C to -103 °C where complete freezing was observed. Initial melting occurred between -58 °C to -60 °C, close to the triple point of CO2 (-56.6 °C). These temperatures indicate this system is a carbon dioxide-rich system, with trace methane as indicated by the depressed initial melting point. Clathrate melting temperatures were consistently in the range of 9.3 °C to 9.8 °C, suggesting trace NaCl (9.8 °C in a pure H2O-CO2 system). The carbonic liquid and gas phases in Type 1 inclusions homogenized into a single carbonic phase via bubble point transition (Tbub(LCV→LC)) in the temperature range of 28.9 °C to 30.2 °C (CO2 critical point 31.1°C). Final homogenization of the aqueous and carbonic phases (Th(LC→L)) occurred between 291 °C and 317 °C.  Hydrothermal fluids within V3 veins at Boulevard are best approximated by the three component H2O-CO2 -NaCl system and have a modeled bulk density of ~0.82 g/cm3, and composition of 16 to 23 mol% CO2 and ~0.03 to 0.8 wt% NaCl. Figure 40 shows fluids at Boulevard were trapped in quartz as a single-phase fluid at conditions above 280 °C and 1 kbar. These minimum trapping conditions correspond to a minimum depth of 3.6 km assuming lithostatic pressures (density of 2800 kg/m3) and 11.3 km assuming hydrostatic pressures (density of 1000 kg/m3).  4.3 Previous Boulevard and Toni Tiger Microthermometry Results Reconnaissance microthermometry by McKenzie (2014) show fluids contained in paragenetically early hydrothermal garnet are aqueous-carbonic (0.67 g/cc bulk density, 5 mol% CO2, < 0.1 wt% NaCl), with minimum trapping conditions of 350 °C and 300 bar. Modelled compositions for hydrothermal fluids in quartz at Boulevard and Toni Tiger were not discernable (Figure 39). Toni Tiger quartz hosted Type 1 inclusions contain a bulk density of 0.88 g/ cm3, ~16 mol% CO2 and ~3 wt% NaCl. Estimated minimum depths were 4.5 km at lithostatic pressures and 12 km at hydrostatic pressures. 61    Figure 39: Pressure-Temperature isochore plots of modeled fluid inclusion trapping constraints for Sugar (Top), Boulevard (Middle) and previously modeled results for Boulevard and Toni Tiger by McKenzie 2014 (Bottom). Isochores are plotted relative to the critical curves in the H2O-NaCl and H2O-CO2 systems, which represent end-member boundary conditions for a single-phase fluid in the H2O-NaCl-CO2 system. 62   Figure 40: A PT-isochore plot containing modeled data from Sugar, Boulevard and Toni Tiger as well as data from the previous study. Arsenian pyrite stability fields, suggested by Buitenhuis 2015 to be mineralizing conditions for the Coffee deposit are represented by the orange box.  4.4 Comparison and relationship to mineralizing fluids  New microthermometric data for Boulevard were close to previously modeled data by McKenzie (2014) in terms of bulk composition, carbon dioxide content, final homogenization temperatures and the slopes and P-T positions of modelled isochores. However, estimated salinity in this study was much lower than the 1-3 wt% NaCl reported by McKenzie. The new estimates of salinity are much closer in composition to that of Sugar as well as the Toni Tiger garnet inclusions. Figure 39 shows the new Boulevard isochores are within range of the previous reconnaissance study and now provide a well constrained range of possible trapping pressures and temperatures for the system. Due to time constraints, Toni Tiger Type 1 fluid inclusions were not investigated using microthermometry. Constraints from the previous study place Toni Tiger quartz inclusions as the upper isochore limit of the Boulevard-Toni Tiger system.  63   Figure 40 shows Boulevard isochores to be on average 0.25-0.5 kbar higher than that of Sugar and ~20 °C lower. Despite these slight differences, both systems share very similar trapping conditions in addition to fluid composition discussed earlier. Isochores for garnet-hosted fluid inclusions from Toni Tiger indicate up to 150°C higher trapping temperature assuming similar trapping pressures compared to subsequent quartz-hotsed fluids.   Arsenian pyrite and white mica stability fields were used by Buitenhuis (2014) to constrain mineralization temperature of the Coffee deposit (orange box in Figure 40). Although a pressure constraint was not provided by Buitenhuis, the petrographic observations of Sugar, Boulevard and Coffee cataclasites and veins indicate mineralization was likely formed in the brittle regime. V3 Quartz grains formed before sulphide mineralization under the same structural regime. P-T-V-X modeled minimum trapping pressures for the V3 quartz grains thus form an upper pressure constraint for mineralization,  thus constraining mineralization pressures to the brittle, shallow crustal zone ~1000 bars. Since Sugar and Boulevard mineralization is associated with arsenian pyrite and white mica precipitation, it is unlikely that the fluid conditions associated with quartz precipitation are directly related to mineralization. However, the possibility of these systems having a common parent ore fluid which eventually cooled and depressurized to conditions conducive to gold ore formation cannot be dismissed. Alternatively, the Boulevard-Sugar system may represent a deeper rooted, hotter system unrelated to Coffee. The superposition of lower temperature sulphides on higher temperature quartz at Sugar and Boulevard may be a result of exhumation related cooling of the system.   An upper bound to PT conditions for the Boulevard-Sugar system was not proposed in previous models. However, since Sugar mineralization and quartz veins are hosted entirely in the Coffee Creek pluton, a reasonable upper constraint on the pressure of vein formation is given by the emplacement pressure of the host granitoids. McCausland and co-workers (2006) proposed an emplacement depth of 11.6-13.1 km and a crystallization temperature of 720-750 °C for the Dawson Range batholith. A suitable P-T upper bound for the Sugar-Boulevard system will be discussed in detail in the next section.      64  4.5 Potential sources of uncertainty in fluid inclusion P-T-V-X modeling  Errors in the P-T-V-X modeling of fluid inclusions from microthermometric data stem partly from inaccuracies in measured phase transitions (e.g., excessive heating rates, instrument error, phase metastability), as well as inherent inaccuracy in the volumetric estimation of fluid phases. The temperature measurements in this study are considered accurate up to ± 0.2 °C at low temperatures and up to ± 4 °C at high temperatures, based on replicate measurements of phase changes in fluid inclusion standards. Volumetric estimation of phases is the largest source of error for P-T-V-X modeling. A poorly estimated fraction of aqueous liquid relative to carbonic phases could result in a disparity in pressure constraints on the order of a 2-10 kilobars. A test model of L= 10% vs L= 90% in the Bakker software (all other inputs constant) revealed a disparity of 9 kbars while L=30% vs L=45% revealed a disparity of 2 kbars. Figure 41 displays a simplified cartoon of the differences between the 2D view of a fluid inclusion vs a potential 3D view.   Figure 41: An illustration of the inherent inaccuracy of volumetric estimation of fluid phases in fluid inclusions.   Some additional factors to be considered in the accuracy of the modeled inclusions in this study are also the amount of methane in the system. Raman analysis has proven the existence of methane in the system, however the precise proportions were unable to be constrained due to the absence of a standard. Additional gases such as methane would also affect the accuracy of the P-T-V-X models. 65  Chapter 5 - Discussion   5.1 Mineralization and Structure: Sugar vs Boulevard vs Coffee The style of gold mineralization is remarkably similar at Sugar and Boulevard, with both systems characterized by auriferous quartz-carbonate-sulphide veins with a Fe-carbonate-sericite-sulphide alteration halo (Figure 41) containing disseminated arsenian pyrite precipitated as poikilitic pseudomorphs of mafic pyroxenes, amphiboles and biotite.  Sugar and Boulevard share a common sulphide paragenesis with multiple generations of mutually overprinting arsenopyrite and arsenian pyrite. Both prospects include sphalerite, stibnite and tetrahedrite as additional minerals associated with gold, however only V3 veins within Sugar’s granitic host rocks observed freibergite. This observation was inferred to possibly be the result of host-rock dependent mineralization. Silver and certain other base metals may have been sourced locally from the granitic rocks at Sugar (not present at Boulevard). However, this assertion cannot be proven until a more thorough geochemical investigation is carried out. A sulphide flooding event occurred at both hydrothermal systems. At Sugar, existing sulphides were replaced by arsenopyrite, whereas at Boulevard, sulphides were replaced by arsenian pyrite. It is unclear why this difference exists between the two systems.  Coffee lacks quartz veining and the same base metal diversity observed at both Sugar and Boulevard, however it still contains disseminated arsenian pyrite of similar textures and replacement style mineralization within sericite alteration zones and cataclasites (reference needed). The absence or lack of significant quartz veining could be due to the depth in the shallow crust at which brecciation occurred during mineralization at Coffee, which produced pressure differentials too low to alter the solubility of quartz in fluids and precipitate significant quartz (Goldfarb, pers. Commun., 2017). Instead, space-generating breccia structures were generated while the host rock was altered by the hydrothermal fluids. The failure of the system to seal these near-surface fractures with quartz resulted in a rock with high sustained permeability for further hydrothermal fluid flux, and ultimately for infiltration by meteoric fluids. This feature of Coffee which allowed the deep and widespread penetration of meteoric fluids caused widespread oxidation and breakdown of the arsenian 66  pyrite, releasing solid solution nanoscopic gold as well as high concentrations of arsenic into the soil. As a result, oxide ore at Coffee is economic to be mined as a high tonnage, low grade gold-only deposit with up to 95% recovery rates via cyanide leaching (Buitenhuis et al., 2015).  Coffee’s apparent lack of sulphide diversity cannot have been a result of host-rock dependence since it shares the same host rocks as Sugar and Boulevard. The base metal sulphides observed at Sugar and Boulevard all occur within the V3 veins. The formation of Coffee as a gold only system may simply have been a function of it’s location at shallow crustal levels which do not allow for the precipitation of quartz veins, thus not allowing for a mechanism of transport and precipitation for these base metal sulphides. A recently discovered anomaly on the Coffee property, Ristretto (Allan, 2016), contains a diverse set of Au-Ag-Cu-As bearing sulphides. Further investigations on this prospect is needed to asses if it has a genetic relationship to Coffee.  Veins of both the Sugar and Boulevard prospects record polyphase brecciation and strike-slip movement overlapping with sulphide precipitation. Similar breccia features are observed at the Supremo zone of Coffee. Mineralized structures at Coffee are also inferred to have formed in a strike-slip fault environment (Sanchez et al., 2014). Clasts of quartz, carbonate and clays as well as matrix material that has undergone grainsize reduction can be observed in all three systems. Matrix compositions are identical with feroan-carbonate, microscopic euhedral cubic pyrite and limonite. Similar styles of brecciation and brittle deformation observed at Sugar, Boulevard and Coffee suggest they may have all formed in a common regional structural regime dominated by strike-slip movement along E-W trending shear zones. Features characteristic of the brittle regime indicate mineralization occurred at shallow crustal depths. Structural trends at Sugar (east-west veins) and Boulevard (northwest trending faults) are also observed at Coffee. All observed structures and veins are steeply dipping and display features of strike slip motion such as slickenlines, dilatational jogs and extensional veins.  67   Figure 42: A comparison of common features shared between Sugar, Boulevard and Coffee.   5.2 Gold Transport and Inferred fluid oxidation state Gold was likely transported as bisulphide complexes (e.g., Au(HS)2-) at Sugar and Boulevard due to the low salinity of the system. During V3 vein formation, quartz precipitated to form the V3 veins and allowed for fluid-wallrock interaction. The reaction of these bi-sulphide complexes with iron from mafic minerals such as biotite, hornblende and pyroxene formed gold-bearing arsenian pyrite as disseminated replacement ore.    Microthermometric results from quarz-hosted fluid inclusion from Sugar, Boulevard and Toni Tiger indicate similar CO2 contents (~20 mol%), salinity (~1-3 wt%) and minimum trapping temperatures (280 °C) and pressures (950 bar). These results indicate all three 68  hydrothermal systems formed under similar physico-chemical conditions, and most likely at similar crustal depths of 3.5 km (lithostat) or 10 km (hydrostat).   Laser Raman spectroscopy analysis (Figure 43) revealed the presence of minor methane in the Type 1 fluid inclusions, indicating that the oxidation state of these fluids is mildly reducing. Since host rocks from all three hydrothermal systems in this study are magnetite bearing, the presence of methane may require that the oxidation state of the hydrothermal fluids has not been buffered by magnetite in the host rocks. This could potentially be explained by high fluid flux from an external, reduced fluid source or shielding of fluids from fresh wallrock by magnetite removal via sulphidation into pyrite, further explained below.     Figure 43: A comparison of fluid inclusions and Raman-measured gas compositions from Sugar, Boulevard and Toni Tiger.  A puzzling issue arising from the Raman results concerns the reason behind the presence of a slightly reduced fluid in a magnetite abundant host rock. In an ideal system, magnetite would react with the external (reduced) fluids and buffer the fluid oxygen fugacity. Three possible explanations can be deduced for the reason behind this observation.  (1) The external (reduced) fluids were sufficiently rapidly fluxed that magnetite-bearing host rocks did not buffer the fluid fO2. 69  (2)  Oxidized rims of titanium enriched minerals such as ilmenite, titanite and other oxides serve as barriers to interaction between magnetite and external fluids, rendering these buffers passive (Dipple pers. Commun., 2017).  (3) Sulphidation of magnetite at Sugar and Boulevard shields fresh magnetite from fluids. (Allan pers. Commun., 2017). The viability of case (1) is difficult to demonstrate without geochemical modelling beyond the scope of this study, and is more likely to occur in a textbook skarn setting where the system is in close spatial relation to an actively degassing pluton as a viable heat and fluid source. Evidence for Case (2) has been observed in Toni Tiger magnetite bearing host rocks which fall within the alteration zone of pre-auriferous calc-silicate alteration. SEM-EDS spot analysis on the altered rims on magnetite grains revealed the presence of ilmenite, titanite and other iron oxide minerals riming an unaltered magnetite core. This oxide rim is not observed at Sugar and Boulevard, however, the reaction of magnetite with reduced sulphur ions will produce pyrite (Case 3). This will effectively shield fresh magnetite from reacting with and buffering the reduced fluid.  In this situation, the oxide rim serves as a protective shield for the magnetite grain much like an aluminum oxide coating applied to stainless steel to prevent rusting. This layer of oxide material likely formed pre- to syn-mineralization, with high fluid flux breaking down magnetite grains and releasing iron to form space filling Pyrrhotite and chalcopyrite (observed to occur in close vicinity to the oxidized magnetite grains) while titanium originally contained with magnetite reacted with calcium rich fluids to form titanite and ilmenite-Fe-oxide rims, sealing away the magnetite grain from further alteration.  Similarly, at Sugar and Boulevard, the pyrite rim serves the same purpose, to shield magnetite from reacting with fluids. In this system, however, sulphidation of magnetite occurs syn-mineralization by reacting with reduced sulphur in the fluid.      70  5.3 Toni Tiger Molybdenite- Source, Transport, Trap The Toni Tiger molybdenum occurrence has shown fluid inclusion compositions indiscernible from that of Boulevard along with similarly aged mineralizing veins. No simple explanation has been given to the source, transport and trap of molybdenite in reduced low salinity fluids. This study attempts to resolve the Toni Tiger anomaly using petrographic observations, fluid inclusion analysis results, as well as available data on molybdenum transport from porphyry systems.  Source The presence of gold in similarly aged mineralizing veins in the Dawson Range gold systems suggests a common, distal source in the deep crust. However, mid-Cretaceous molybdenite occurrences such as Toni Tiger are rare in the Dawson Range, and thus the source of the molybdenite is inferred to be local. Further evidence lies in the presence of methane in Type 1 fluid inclusions within quartz-molybdenite veins at Toni Tiger, suggesting an inefficient, unconventional, short-lived transport mechanism for the molybdenum.  A confident establishment of the molybdenum source would require a detailed and thorough geochemical analysis, targeting samples from both proximal and distal rock units in relation to the molybdenum anomaly. However, some geochemical data from the Late Permian leucogranite host rock at Toni Tiger has displayed significant amounts of molybdenum, therefore has been inferred to be the source of the anomaly (Allan, pers. Commun. 2017). Transport  Molybdenum is preferentially transported in fluids with high fO2 as molybdenum trioxide, MoO3 (Hurtig and Williams-Jones, 2014).  Molybdenum solubility has been shown in Hurtig’s experiments to increase with temperatures, pressure and oxygen fugacity.  The low salinity fluid composition observed in fluid inclusions at Toni Tiger are ideally modeled in the H-O-Cl-S bearing gas system Mo-stability fields (Figure 44). The low salinity fluid at Toni Tiger results in molybdenum being transported as molybdenum trioxide rather than as chloride complexes.  71   Initially (Step 1 in Figure 44), the low salinity, low fO2 fluid infiltrates the leucogranite host rock while carrying gold as bisulphide complexes. Magnetite in the host rock reacts with this fluid and releases titanium to produce ilmenite, titanite and an impermeable oxide layer. This reaction allows for a slight increase in the fO2 to sufficiently mobilize molybdenum within the leucogranite as trioxide compounds.     Figure 44: A modified phase-stability diagram of molybdenum under fixed hydrothermal conditions displaying molybdenite and its trioxide phase with their relative oxygen fugacity. The redox pathway taken in the Toni Tiger system is labelled as progressive arrows (Hurtig and Williams-Jones, 2014). Trap  The newly mobilized molybdenum trioxide compounds are focused into fractures and veins. The magnetite buffer is short-lived as further interaction with the hydrothermal fluids seals the magnetite from the system with an impermeable oxide layer. Continued flow of deep crustal fluids into the system brings the fO2 down to original levels (Step 2 in Figure 44), destabilizing the trioxide complexes and precipitating molybdenite preferentially over gold or arsenian pyrite. One analogue to Toni Tiger is the Lucky Joe prospect, which contained Jurassic aged molybdenite veins as a result of remobilization of Mississippian aged molybdenite (Allan et al., 2013).   This study proposes the orogenic molybdenite model above, summarized in Figure 45 as a possible explanation to the Toni Tiger molybdenite occurrence within a gold system. Alternatively, a simpler model would be an intrusion-related molybdenite source, whereby 72  molybdenum is transported as a trioxide complex within fluids from a de-gassing unexposed pluton, and is precipitated within the meta-aplite or skarn host rock during a sudden introduction of slightly reduced fluids. However, as suggested earlier, evidence of such an intrusion is yet to be found.      Figure 45: A schematic cartoon of the orogenic molybdenum model, which proposes remobilization of Late Permian molybdenite into mid-Cretaceous aged veins as a result of changes in fluid oxidation state.  5.4 Paragenesis The paragenesis for Sugar, Boulevard and Toni Tiger are lined up in Figure 46. Sugar, Boulevard and Toni Tiger have different high temperature vein and alteration histories which enriched the host rock with mafic minerals such as biotite and amphibole. Contact metamorphism from the Coffee Creek plutonic suite and subsequent dikes produced weak hornfelsing and biotite alteration and likely increased the competency of the YTT host rock. All three hydrothermal systems share a similar inferred mid-Cretaceous age of mineralization (highlighted in orange). At Sugar and Boulevard, the V3 event occurs together with brecciation and cataclasis, indicating that once formed, veins focused shear stress and were repeatedly reactivated. Sugar V3 veins were observed to cut the diorite dikes, thus the V3 veins are spatially and structurally related to the diorite dikes (mKdW) observed at Sugar.  73   Figure 46: Paragenesis of Sugar, Boulevard and Toni Tiger 74  5.5 Longline- Past Au Producer  Research by Joyce (2002) shows Longline shares the same quartz-carbonate-sulphide veins as the Sugar-Boulevard system. Sulphide minerals include galena, sphalerite, arsenopyrite, pyrite and tetrahedrite. Auriferous veins are associated with muscovite, sericite, Fe-carbonate, pyrite, arsenopyrite, quartz, a similar assemblage to the Sugar-Boulevard system, with the exception of tourmaline, which is found in Longline’s auriferous vein alteration halo. Native gold is found within auriferous veins while no report of arsenian pyrite has been documented. Longline is also strongly structurally controlled by NNW striking, ENE dipping dextral strike-slip and brittle, extensional faults, with shallowly dipping veins infilling dilatational jogs.  Auriferous vein quartz precipitated from low salinity fluids (0-10 wt%), rich in CO2 with trace N2 at 260-300 °C and 1.3-1.9 kbar (Figure 47). These veins are calculated to have formed at depths of 5-7 km assuming lithostatic pressures (Joyce, 2002). The paleofluid composition and trapping conditions of fluids reported by Joyce matches closely to that of the Sugar-Boulevard system.   Figure 47: P-T model with Longline trapping pressures and temperatures superimposed on Sugar and Boulevard data.  75  5.6 An “invisible” Heat Source Preliminary 40Ar/39Ar cooling ages of hydrothermal sericite associated with V3 veins at Sugar places the likely age of mineralization within error of Boulevard mineralization (M. Allan, pers. comm., 2017). Longline Au mineralization further northwest in the Dawson Range has a reported age of 92 Ma (Joyce, 2002). Mineralization of the Sugar-Boulevard (and possibly Coffee) and Longline hydrothermal systems are 4-8 million years younger than the youngest U-Pb crystallization age of the Coffee Creek pluton (ca. 99 Ma, McKenzie et al., 2013).  No ca. 96-92 Ma intrusions synchronous with mineralization in the Dawson Range have been reported, and yet fluid inclusion constraints demonstrate the hydrothermal system had minimum V3 vein forming temperatures of up to 300° C. Before any mineral deposit models are proposed, an explanation for the heat source of the mid-Cretaceous Dawson Range gold systems must be established.  5.6.1 Heat Source and Fluid Source for Dawson Range gold systems The origin of fluids in the Sugar-Boulevard-Longline systems is unclear. Previous studies by Joyce (2002) and McKenzie (2013) concluded through stable isotope analysis that although fluids cannot be distinguished between a magmatic (exsolving pluton fluids) or orogenic source (metamorphic fluids) the Dawson Range Batholith is not the source of the fluids for Longline and Boulevard mineralization. This places the DRB’s role in the system to be a passive, competent host.  Three contending arguments for the thermal driving force behind mineralization of the Dawson Range gold systems include: (1) Unexposed 95-96 Ma intrusions underlying the hydrothermal systems (McKenzie 2014).  (2) A deep crustal heat & fluid source from prograde metamorphism. (3) Residual heat from the cooling Dawson Range Batholith (Allan et al., 2013).  Intrusion related heat source and fluid source The intrusion-related gold model of Case (1) proposes intrusions underlying the Boulevard, Sugar and Longline systems at the time of mineralization. This model proposes 76  that fluids are sourced from the exsolving and degassing fluids of a cooling and crystalizing pluton, while the newly intruded pluton provides heat to country rocks via advection and convection.  As seen from Figure 2 the distances between Sugar, Boulevard, Coffee and Longline covers a large area (200 km on strike length). Numerous U-Pb isotope studies have been conducted in the Dawson Range, with no mid-Cretaceous age less than 99 Ma ever been reported. Therefore, it is reasonable to conclude the presence of this hypothetical intrusion is highly unlikely.  Prograde metamorphic fluids Case (2) proposes a epizonal to mesozonal orogenic gold model in which devolatilization reactions at deeper crustal levels during prograde metamorphism provides the fluids thermally equilibriated with lower crustal temperatures provide heat from the lower crust or a distal lower crustal intrusion via a trans-crustal shear zone or fault Previous sulphur isotope analysis was unable to resolve the signature between an intrusion-sourced fluid, meteoric fluid and a metamorphic fluid (McKenzie, 2013), however the lead isotopic results of Joyce (2002) are inconsistent with the DRB as the source for the metals (and fluids) related to mineralization.  DRB residual heat source Case (3) proposes that residual heat from the cooling DRB could be sufficient to drive a mineralizing hydrothermal system up to 8 million years after crystallization. This case proposes the fluid source to be a combination of metamorphic and meteoric fluids mixed and convected by latent heat from the DRB along brittle structures at shallow crustal levels.   This scenario argues the size of the Dawson Range batholith (up to 200 km in strike length) would allow it to retain the heat necessary to achieve mineralization and fluid inclusion trapping temperatures documented for Boulevard and Sugar. To further investigate the validity of this argument, the Dawson Range batholith was modeled to track heat loss over time.   77   5.6.2 Thermodynamic model for batholith cooling rates A one-dimensional heat flow model for post-crystallization, sub-solidus cooling of the Dawson Range batholith was constructed by applying the thermodynamic heat flow equations of Carslaw and Jaeger (1992). The working consensus states that the DRB is a flat, sill-like structure intruded into a strike-slip shear zone created by the Big Creek fault, although Johnston (1999) argues for a sub-vertical orientation for the DRB. Both conflicting orientations agreed upon a sheet-like structure, which formed the assumption of the shape of the DRB. A 10 km half-thickness was set to the DRB based on map exposure, which is a reasonable estimate for a batholith of this size. The solidus was assumed to be at 750 °C based on the average values of DRB crystallization to be 720-750 °C for granodioritic compositions (McCausland et al. 2006).    Figure 48: A simple sheet model of the DRB with a half-thickness of 10 km, Carslaw and Jeager’s heat loss equation and blue arrows indicating the direction of heat flow. T0: temperature of granite crystallization, 750 °C. erf: Error function. a: Half-thickness of DRB. z: Distance from the centre of the batholith. k: thermal conductivity constant for rocks, 0.01 W/(mK). t: time since crystallization of granite.  The parameters and assumptions above were used with the heat flow equations in Microsoft Excel to generate “Distance from the DRB center” vs temperature plots with respect to time (in increments of 1 million years) since crystallization of the batholith. The model was first carried out assuming no exhumation (Figure 49). The modeled temperature curves display the decrease in temperature with distance away from the batholith as well as an overall decrease in temperature over time. An important observation is the disparity 78  between the temperature within the batholith (pink) and the temperature in the wallrock (YTT metamorphic rocks). The difference in temperature between the batholith and the wallrock decreases with time and gradually reaches equilibrium with wallrock temperatures. In this model, the wallrock temperatures were constrained by the lowest temperature feature recorded in the hydrothermal system. Post-mineralization epithermal vein textures were recorded by Buitenhuis (2014), and hence set the wallrock boundary condition to 150 °C.   The area of interest for the modeled heat loss curves were constrained to ±5 km from the DRB-wallrock contact, since the Sugar, Boulevard, Coffee and Longline are located within (Sugar, Longline, Kona zone at Coffee) or at the DRB-YTT contact (Coffee and Boulevard). Figure 49 B zooms in on the area of interest, with trapping temperatures from fluid inclusion P-T-V-X modeling. Results indicate minimum trapping temperatures for Sugar, Longline, Boulevard and Toni Tiger quartz fall below the modeled batholith temperatures up to 8 million years after crystallization of the DRB. The Toni Tiger garnet trapping temperatures were maintained at 5-6 million years after crystallization of the DRB. Considering the mineralization age of 96 Ma for Boulevard, these results indicate latent heat in the DRB is still sufficiently hot enough to achieve V3 vein forming conditions in the absence of exhumation effects.  Aluminium in hornblende geothermobarometry (McCausland et al. 2006) and recent (U-Th)/He thermochronology (Gaudreau et al., 2017) have provided evidence for regionally significant mid-Cretaceous exhumation of the Dawson Range batholith and its surrounding Yukon-Tanana terrane host rocks. Therefore, a thermodynamic model accounting for this exhumation must be constructed. Figure 50 shows a model of heat loss in the DRB with an average exhumation related cooling rate of -10 °C/ million years (Gaudreau et al., 2017).  The wallrock temperatures were set to correspond with the estimated emplacement depth of the DRB ~12 km (McCausland et al., 2006), giving a temperature of ~ 430 °C from the geotherm.  79   Figure 49: Thermally modeled heat loss for the DRB with respect to distance with time with the assumption of no exhumation. The minimum temperature of wallrock was constrained by the lowest temperature hydrothermal feature observed at Coffee.   80   Figure 50: Thermally modeled heat loss for the DRB with respect to distance with time with the assumption of an exhumation-related cooling rate of -10 °C/ million years. 81  Figure 50 B shows the area of interest in a system modeled with significant exhumation. Residual heat from the cooling batholith in this scenario far exceeds minimum trapping temperatures for Sugar, Boulevard and Toni Tiger modeled with fluid inclusion data. A possible reason behind the disparity between thermodynamically modeled values and fluid inclusion modeled values lies within the crustal depth for the formation of V3 auriferous veins. Petrographic observations indicate V3 veins form in brittle regimes along with cataclasites. The temperatures modeled above at 8 million years (470 °C) reflect temperatures in deep crustal levels. It is possible that brecciation, shearing and V3 veins only formed once the DRB and the wallrock were exhumed to shallow crustal levels and temperatures. Another possible reason for this disparity could be due to assumptions taken in generating the thermodynamic heat flow models discussed below.     The thermodynamic heat loss curves generated above can be used as upper bounds to constrain P-T-V-X fluid inclusion models as maximum trapping temperatures for V3 quartz veins with respect to time after crystallization. The exhumation rate of -10 °C/ million years also allows for an estimate of the depth of the system in the crust with respect to time since emplacement, thus allowing for a corresponding pressure. Although, such constraints are only as accurate as the assumptions made in constructing the model.   A possible cause to the widespread shear-related hydrothermal activity in the Dawson Range ~95-96 Ma is the collapse of thickened crust in the Northern Canadian Cordillera with subsequent lithospheric mantle delamination (Pryer et al., 2017).  5.6.3 Short-comings of the Thermal model Parameters relating to the DRB such as its half-thickness and sheet structure are weakly constrained by map exposure, geophysical data and limited literature on the DRB. The modeling of exhumation rate in the study area is highly simplified. This model assumes a uniform exhumation rate for the entire study area, which is highly unlikely in nature. McCausland’s data (2006) show variable exhumation throughout the Dawson Range during the mid-Cretaceous.  The effect of exhumation rates was only applied to the YTT wallrocks in the model while the DRB was assumed to contain and loss the same amount of heat throughout the 82  exhumation process. During exhumation, the DRB should experience heat loss at a higher rate than the background wallrocks.  Applying the exhumation rate to the DRB would require more advanced modelling approaches that are beyond the scope of this study.  Finally, the heat flow equations of Carslaw and Jeager assume the DRB consists of a single phase of heat injection into the system. Studies on the DRB have shown that the DRB is a multi-phase batholith, with multiple phases of magmatism over ca. 15 m.y. Therefore, the volume of magma added at ca. 99 Ma is likely minor relative to the much larger volume of previously crystallized magma in the DRB.   5.7 A mineral deposit model for the Dawson Range gold systems (DRGS)  An orogenic gold model has been proposed for the Coffee, Longline and Boulevard systems (Joyce, 2002; Allan et al., 2013; Mackenzie et al., 2013; McKenzie, 2013; Sanchez et al., 2014; Buitenhuis et al., 2015) while Sugar was proposed to be an intermediate sulphidation epithermal system (Bartlett, 2016). These mid-Cretaceous gold systems share some common characteristics with a few gold deposit models (Figure 51).   The low temperatures of mineralization of the DRGS constrained by arsenian pyrite stability fields fall within the range of low-intermediate sulphidation epithermal deposits (Groves et al., 1998), carlin gold deposits and epizonal orogenic gold deposits. DRGS veins are not similar in age to their host rocks and are made up of alteration assemblages that do not contain adularia. Furthermore, epithermal textures and veins have been determined to be post-mineralization lower temperature features at Coffee (Buitenhuis, 2015), thus eliminating the epithermal model. Carlin systems are an attractive candidate deposit type for Coffee since both contain disseminated gold-hosting arsenian pyrite in the absence of quartz veins at shallow depths in the crust (Cline et al., 2005). DRGS are not hosted in reactive carbonate host rocks, although some of the YTT metasediments observed at Boulevard may contain reactive calcareous protoliths. However, the CO2 content in fluids observed at Sugar and Boulevard are too high for Carlin gold systems. Most importantly, fractures and fault structures at Sugar, Boulevard, Longline and Coffee were active during mineralization, unlike passive, deep fault structures in Carlin gold systems.  83   The presence of molybdenite and skarning at Toni Tiger originally raised suspicion towards an intrusion related gold model (IRGS). The Au-As-Sb association in the DRGS is observed in proximal and distal veins in IRGS (Hart and Goldfarb, 2005). Furthermore, fluids at Boulevard and Sugar share the same low salinity, high CO2 composition as that in IRGS. However, mineralization temperatures in IRGS are high compared to mineralization temperatures constraints for the DRGS. The zonation mineralization haloes in IRGS are not observed in the DRGS, and most importantly, a causative 95 Ma pluton has not been identified. As discussed earlier, Toni Tiger molybdenite remobilization can occur without an intrusive source, thus the IRG model can be eliminated from consideration.    DRGS shares many important characteristics to orogenic gold systems. A high Au:Ag ratio is observed across all systems, with Coffee being a gold-only deposit, with the exception of the Ristretto Au-Ag-Cu-Pb prospect, whose genetic relationship to Coffee is still under investigation. The DRGS are hosted in greenschist facies and granitic hosts in close spatial association to transcrustal fault zones. Alteration occurs as carbonate-sericite-quartz-sulphide assemblages with the majority of the gold and sulphides distributed within the alteration halo rather than the vein itself. Finally, a low salinity, CO2 rich fluid with trace methane is observed within fluids in DRGS, although this feature does not help in distinguishing between orogenic gold systems and IRGS (Hart and Goldfarb, 2005). Orogenic gold systems occur at a large range of depths and temperatures (Groves et al., 1998). DRGS occur in the brittle shear regime, hence are inferred to be shallow crustal deposits. Mineralization temperatures constraints for Coffee place it in an epizonal classification while the Boulevard-Sugar-Longline systems fall within the epizonal and shallow mesozonal classification (Groves et al., 1998) depending on the use of the lithostat or hydrostat in constraining the depth of emplacement.  84   Figure 51: A comparison table of deposit types with their respective characteristics and their fit to the Coffee and the Boulevard-Sugar-Longline gold systems (Groves et al., 1998; Cline et al., 2005; Hart and Goldfarb, 2005; Hart, 2007).  85  Chapter 6 - Conclusions:   6.1 Metallogeny of the Dawson Range gold systems Sugar, Boulevard and Longline are mid-Cretaceous sheeted auriferous quartz-carbonate-sulphide composite vein systems formed in brittle shearing, strike-slip regimes at epizonal to mesozonal depths (3.5 km to 10 km). Gold mineralization at Sugar and Boulevard is hosted in arsenian pyrite replacing mafic minerals and magentite in the host rock as well as free gold at Boulevard. These three hydrothermal systems share the same low salinity (~5 wt%), carbon dioxide-rich (~22 mol%) paleofluid with trace methane. Fluid inclusions from auriferous quartz veins in these hydrothermal systems have similar trapping conditions at ~300 °C and 1 kbar.   The BV-SG-LL hydrothermal systems along with the 5 Moz. Coffee gold deposit, make up a series of mid-Cretaceous gold systems with a strong Au-As-Sb signature, hosted in the Dawson Range batholith and the Yukon-Tanana terrane. Rimmed and/or spongy textured arsenian pyrite as well as brittle brecciation structures at Boulevard and Sugar are also observed at the Coffee Gold deposit. Therefore, a potential genetic relationship can be drawn from these observations. A comparison of fluid inclusion P-T-V-X models to arsenian pyrite stability fields reveals that the modeled inclusions do not represent the mineralizing fluid for these systems. Petrographic and fluid inclusion constraints suggest that the Boulevard-Sugar system represents a deeper-rooted, higher temperature system as compared to Coffee, however, the possibility of these gold systems sharing a common paleofluid cannot be dismissed. The difference in expression of mineralization at Coffee vs the Boulevard-Sugar systems are simply a function of the depth of shearing- pressure differentials being a major factor in the precipitation of quartz veins.  The Toni Tiger molybdenite occurrence is the result of remobilization and re-concentration of molybdenum sourced locally from the Late Permian aged leucogranite host rock during the 96 Ma gold-mineralizing event. Magnetite in the host rock serves as a buffer for the reduced gold bearing fluids, raising the fO2 of the fluid to levels high enough to transport molybdenum. Once the titanite-ilmenite-oxide rim seals the magnetite off from the 86  system, the fluid fO2 drops and molybdenite precipitates locally in quartz veins instead of gold.  The Sugar-Boulevard, Longline, Toni Tiger and potentially Coffee gold mineralization event could potentially be the result of lithospheric mantle delamination in the mid-Cretaceous 4-8 million years after the crystallization of the DRB and causing significant exhumation of the DRB and rapid changes in regional stress regimes (Gaudreau et al., 2017; Pryer et al., 2017). This event triggered the shear-hosted gold mineralization seen throughout the above hydrothermal systems within the passive, competent DRB host rock as well as the brittle, hornfelsed YTT host rocks in contact with the DRB. A combination of lower crustal fluids and heat as well as residual heat from the crystalized DRB drives fluid flow and mineralization in the system.  This study proposes an epizonal to mesozonal, brittle, structurally hosted orogenic gold model for the Boulevard-Sugar system, as part of a significant, regional, mid-Cretaceous metallogenic event in the Dawson Range.  6.2 Exploration Implications Figure 52 highlights similarities between Dawson Range gold systems. Temporal association of mineralization to the mid-Cretaceous, post DRB crystallization is the key to identifying systems of this major metallogenic event. Genetic association of auriferous quartz-carbonate sulphide veins and cataclasites to second-third order faults and shear structures and trends parallel to the northwest trend of the DRB make such systems locatable on magnetic lows and DC-IP highs in geophysical survey data. The presence of rimed and poikiloblastic (spongy) arsenian pyrite within wide sericite-carbonate wallrock alteration halos is correlated to the Au-As signature, tracible in soil anomaly surveys.   Sugar has limited economic potential since unlike Coffee, gold-bearing arsenopyrite and arsenian pyrite grains are still intact and formed in small amounts, with most veins not exceeding 8 cm in width. Extraction of gold trapped in these arsenic bearing phases requires high amounts of energy input. Longline was a past producer since it harboured native gold within its veins as well as in wallrock alteration. Native gold is also found at Boulevard, which is still being explored for possibilities as a potential producer. Coffee’s unique 87  economic potential in the area is due to pervasive weathering and oxidation that has broken down aresenian pyrite grains and released the nanoscopic gold within. Thus, informed decisions must be made before deciding to pursue the economic potential of mid-Cretaceous gold-bearing veins in the Dawson Range.   The DRGS are spread over a wide area in the Dawson Range, hence the metallogenic event producing mineralization in the area is vast. Locating another low grade high tonnage Coffee-style gold system is likely in the area provided the area has similar brittle structures, Au-As relationship, and undergone pervasive weathering.     Figure 52: A table displaying common characteristics of Dawson Range gold systems resultant of this study. Features highlighted in green can potentially be used as criteria to identify gold systems in the Dawson Range related to this metallogenic event.   88  6.3 Future work  Several questions remain unanswered from this study. Petrographic investigation into microtectonic structures have revealed many shear sense indicators particularly in cataclasite samples for Boulevard and Sugar (BV22-73.23m and SGWS16-13). However, thin sections were not oriented for this study. A structural investigation into Boulevard and Sugar could answer important questions to the structural evolution of the Dawson Range during the mid-Cretaceous in relation to Coffee. The fluid evolution of this system appears to be complex, with Type 2 LV inclusions within the high temperature myrmekite veins at Sugar pending microthermometric investigation. Further measurements on the Toni Tiger fluid inclusions would contribute a higher statistical confidence in the similarity between fluids in this system to Boulevard and Sugar.  Furthermore, a geochemical analysis to determine the source, transport and trap for molybdenum in a reduced fluid at Toni Tiger could reveal a new mechanism for transport of orogenic molybdenum. Revisiting the Longline sample suite to search for arsenian pyrite in comparison to Sugar and Boulevard could reveal if these systems are related and explain the disparities in mineralization age and mineralogy (Tourmaline at Longline). Most importantly, the reason behind the presence of native gold at Boulevard and Longline is still unknown and is worth further investigation.             89  References Allan, M.M., Mortensen, J.K., Hart, C.J.R., Bailey, L.A., Sanchez, M.G., Ciolkiewicz, W.,McKenzie, G.G., and Creaser, R.A., 2013. Magmatic and metallogenic framework of west-central Yukon and eastern Alaska: Society of Economic Geologists, Special Publication, v. 17, pp. 111-168. Allan, M.M., 2016. Insights into the structural setting of Ristretto and Sugar zones, Coffee Gold Project, Yukon: Confidential report to Goldcorp Inc., 8 p.  Bakker, R. 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(compilers), 2004, YukonAge 2004: A database of isotopic age determinations for rock units from Yukon Territory: Yukon Geological Survey (CD-ROM). Buitenhuis, E., 2014. The Latte gold zone, Kaminak’s Coffee gold project, Yukon, Canada: geology, geochemistry, and metallogeny: Unpublished MSc thesis, University of Western Ontario, London, Ontario, 197 p. Buitenhuis, E., Boyce, L. and Finnigan, C., 2015. Advances in the mineralization styles and petrogenesis of the Coffee gold deposit, Yukon. In: Yukon Exploration and Geology 2014, K.E. MacFarlane, M.G. Nordling and P.J. Sack (eds.), Yukon Geological Survey, p. 29-43. Carslaw, H.S. and Jarger, J.C., 1992. Conduction of Heat in Solids (2nd edition), Bristol, J.W. Arrowsmith Ltd, 510 p. ISBN 0-19-853368-3  Cline, J.S., Hofstra, A.H., Muntean, J.L., Tosdal, R.M., and Hickey, K.A., 2005. Carlin-Type Gold Deposits in Nevada: Critical Geologic Characteristics and Viable Models: Economic Geology 100th Anniversary Volume p. 451–484. 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Mid-Paleozoic to early Mesozoic tectonostratigraphic evolution of Yukon Tanana and Slide Mountain terranes and affiliated overlap assemblages , Finlayson Lake massive sulphide district, Geological Association of Canada, Special Paper, 45, pp. 75–106. Nelson, J.L. and Friedman, R.M., 2004, Superimposed Quesnel (late Paleozoic-Jurassic) and Yukon Tanana (Devonian-Mississippian) arc assemblages, Cassiar Mountains, northern British Columbia: field, U-Pb and igneous petrochemical evidence: Canadian Journal of Earth Sciences, v. 41 , p. 1201-1235. Nelson, J.L., Colpron, M., Piercey, S.J., Dusel-Bacon, C., Murphy, D.C. and Roots, C.F., 2006, Paleozoic tectonic and metallogenic evolution of the pericratonic terranes in Yukon, northern British Columbia and eastern Alaska, in Colpron, M. and Nelson, J.L., eds., Paleozoic Evolution and Metallogeny of Pericratonic Terranes at the Ancient Pacific Margin of North America, Canadian and Alaskan Cordillera: Geological Association of Canada, Special Paper 45, p. 323-360.  Piercey, S.J., Nelson, J.L., Colpron, M., Dusel-Bacon, C., Simard, R.-L. and Roots, C.F., 2006, Paleozoic magmatism and crustal recycling along the ancient Pacific margin of North America, northern Cordillera, in Colpron, M. and Nelson, J.L., eds., Paleozoic Evolution and Metallogeny of Pericratonic Terranes at the Ancient Pacific Margin of North America, Canadian and Alaskan Cordillera: Geological Association of Canada, Special Paper 45, p. 281-322. Pryer, L., Gleeson, S.A., and Johnston, S.T., 2017. The evolution of “mid” Cretaceous Omineca Magmatic Belt granites in the Northern Canadian Cordillera: A product of mantle lithosphere delamination: Cordilleran Tectonics Workshop 2017 Talk.   Roedder, E., 1984, Fluid Inclusions: Reviews in Mineralogy, v. 12, p. 646.  Sánchez, M.G., Allan, M.M., Hart, C.J.R. and Mortensen, J.K., 2014. Extracting ore-deposit controlling structures from aeromagnetic, gravimetric, topographic, and regional geologic data in western Yukon and eastern Alaska: Society of Exploration Geophysicists and American Association of Petroleum Geologists, Interpretation,Vol. 2, No. 4 (November 2014); p. SJ75–SJ102. 95  Simard, R.-L., 2003, Geological map of southern Semenof Hills (part of NTS 105E/1,7,8), south-central Yukon (1:50,000 scale): Yukon Geological Survey, Open File 2003-12. Tempelman-Kluit, D.J., 1979, Transported cataclasite, ophiolite and granodiorite in Yukon: evidence of arc-continent collision: Geological Survey of Canada, Paper 79-14 , 27 p. Villeneuve, M.E., Ryan, J.J., Gordey, S.P., and Piercey, S.J., 2003, Detailed thermal and provenance history of the Stewart River area (Yukon-Tanana terrane, western Yukon) through application of SHRIMP, Ar-Ar and TIMS [abs]: Geological Association of Canada/Mineralogical Association of Canada, Abstracts, v. 28, p. 344. Wainwright, A.J., Simmons, A.T., Finnigan, C.S., Smith, T.R. and Carpenter, R.L., 2011. Geology of new gold discoveries in the Coffee Creek area, White Gold District, west central Yukon. In: Yukon Exploration and Geology 2010, K.E. MacFarlane, L.H. Weston and C. Relf (eds.), Yukon Geological Survey, pp. 233-247.     96          Appendix A: Sample database   Sugar SGWS16 Toni Tiger          TTWS16 Hole ID Sample # Depth Sample Description Thin Section Thick Section Comments for fluid inclusion Suitability for microthermometrySGD0001 SGWS16-01 31.89-32.0mSheared Quartz vein with sooty sulphides and Chlorite-sericite altered host rock (Diorite) Yes No Garnets present, worth revisitingSGD0001 SGWS16-02 145.2mHighly oxidized chlorite altered host with Quartz carbonate vein No NoSGD0004 SGWS16-03 21.2mQuartz vein with calcite infill and sulphides replacing biotite within vein. Yes YesLarge inclusions with clear paragenesis within quartz in mineralized vein LV(0.7)SGD0004 SGWS16-04 22.3m Simple quartz vein in chlorite altered microdiorite No NoSGD0004 SGWS16-05 41.44m Destroyed on transport No NoSGD0004 SGWS16-06 121.25mLate stockwork veins cross cuting sulphide veinlets and earlier quartz veins Yes YesGood inclusions wthin small quartz grains in mineralized veinSGD0004 SGWS16-07 163.2mPegamtitie vein with pyrite replacing mafic minerals within vein in diorite host rock Yes YesLarge inclusions LV(0.6) within quartz grains (mineralized)SGD0008 SGWS16-08 147.0-147.2mSheared Quartz vein with sooty sulphides and Chlorite-sericite altered host rock (Diorite) + Late carbonate veins and oxidation Yes YesLarge primary inclusions LV(0.6) seen in edges of quartz vein. Centre is too small and complexSGD0008 SGWS16-09 161.0-161.2mSilica flooding / pegmatite vein in oxidized and silicified Granitic host rock. Elongation of silica grains suggest syn/post vein deformation No NoSGD0008 SGWS16-10 163.5-163.6mQuartz vein with sooty sulphide deposited within. Host: Diorite with epidote alteration and disseminated sulphides Yes NoSmall LV(0.6) inclusions in quartz vein near mineralizationSGD0008 SGWS16-11 178.2-178.3m Quartz vein with sulphide veinlets Yes No No good inclusionsSGD0008 SGWS16-12 191.0-191.1m Quartz vein with bleaching halo Yes YesNorth part of section has f=inclusion rich quartzSGD0011 SGWS16-13 21.9-22.0mQuartz Vein with diseminated sulphide in selvage and in host rock. Oxidized (Diorite) Yes No No good inclusionsSGD0012 SGWS16-14 203.1-203.2mPegamtite vein in highly cholorite altered indistinguishable host rock No No NoSGD0005 SGWS16-15 186.1-186.4m Quartz Sulphide Veinlet swarm Yes NoVery tiny inclusions, some potential ones in the massive qz veinsSGD0005 SGWS16-16 186.1-186.4m Quartz-Sulphide breccia (sericite altered) Yes No Carbonate-qz vein, no good inclusionsSGD0005 SGWS16-17 183.6-183.7mDuctily deformed host rock with slightly boudinaged and sheared quartz veins. Massive pyrite on selvages of deformed quartz veins as well as on later fractures in rock No NoSGD0005 SGWS16-18 305.16-305.25m Sooty sulphide veinlets with Quartz veins. yes No No good inclusionsSGD0007 SGWS16-19 52.2-52.35m Pegmatite Vein with Myrmekitic texture Yes YesSome promising inclusions in myrmekite and outside vein, overall quite smallSGD0007 SGWS16-20 52.2-52.35mRepresentative Chlorite epidote vein with chlroite alteration halo and sericification in Diorite host No NoSGD0007 SGWS16-21 106.2-106.3m "stylolite" within sooty sulphide-quartz vein Yes No Tiny inlcusions in a qz-calcite veinSGD0007 SGWS16-22 106.2-106.3m "stylolite" within sooty sulphide-quartz vein Yes YesLarge inclusions, may not be related to mineralizationSGD0007 SGWS16-23 127.7-127.75m Sheared Quartz vein with sooty sulphide vein Yes No No good inclusionsSGD0007 SGWS16-24 168.16-168.20mQuartz veinlets with chlorite- sericite alteration halo Yes No No good inclusionsSGD0007 SGWS16-25 183.1-183.25mSheared Quartz vein with sooty sulphides and Chlorite-sericite altered host rock (Diorite) yes No No good inclusionsSGD0007 SGWS16-26 206.9-206.95m Not taken No NoSGD0007 SGWS16-27 217.6-217.8m Pegmatite vein with quartz infill Yes NoSmall inclusions, majority of quartz deformed, perhaps qz in groundmassSGD0007 SGWS16-28 233.19-233.35mLarge 5cm wide pegmatite vein with myrmeketic texture, disseminated biotite and intruding a microdiorite host No. NoSGD0007 SGWS16-29 233.80-233.9m Not taken No NoSGD0007 SGWS16-30 318.6-318.8mSmoky combed quartz vein with carbonate vein cross cuting + oxidation Yes No No decent sizesSGD0007Named as Hole ID and depth 217.2mRepresenatative sample of microdiorite with contact with chlorite-epidote-sericite alteration halo No NoSGD0007Named as Hole ID and depth 7.5mRepresentative sample of Diorite unit. Oikiocrystic biotite in a plagioclase -quartz groundmass. No NoSGD0007Named as Hole ID and depth 34.6mAndesite Dike representative sample. Porphyritic plagioclase-quartz crystals in an amphibole rich groundmass No NoSGD0007Named as Hole ID and depth 36.5mMicro-diorite and Andesite dike contact (Representative sample) Yes NoSGD0007Named as Hole ID and depth 292.1m Chacedonic quartz in diorite host Yes NoNot chalcedonic quartz, rather qz calcite vein, no good inclSGD0007Named as Hole ID and depth 122.8mRepresentative vein for paraganesis. 2 generations of quartz (Combed + Infill) and Calcite + Sooty sulphides and smoky quartz. Yes No A: Not very decentB: Possiblity of fluid inclusion petrographySGD0005Named as Hole ID and depth 322.1mSheared Quartz vein with sooty sulphides and Chlorite-sericite altered host rock (Diorite) Yes No No good inclusionsCFD0603 CFWS16-01 195.7-195.9mQuartz-K-spar veins offset by faulting and hosted in augen gneiss Yes No Some decent ones in qz and calciteSample # UTM Easting UTM Northing Elevation (m) Sample Description Thin Section Thick SectionTTWS16-01 578003 6966533 1372Calc-silicate altered host rock with barren quartz veins, quartz-garnet veins and fractures displaying cross cutting relationship. Green, chlorite-actiniloite-biotite alteration is observed throughout. Yes NoTTWS16-02 578003 6966533 1372 Calc-silicate host with barren quartz vein and quartz garnet vein Yes NoTTWS16-03 578048 6966516 1380 Quartz garnet vein in calc-silicate host Yes NoTTWS16-04 6968326.32 628931.8 1358 Quartz-moly vein from leucogranite host rock No NoTTWS16-05 6968326.32 628931.8 1358 Quartz-moly vein from leucogranite host rock Yes NoTTWS16-06 6968326.32 628931.8 1358 leucogranite host rock with vuggy barren quartz vein No No  99          Appendix B: Fluid inclusion Microthermometry data    Sample ID FIA_Chip FIA_ID FIA_min FIA_pet FI_ID FI_Phases CO2_L fraction L- fraction FI_x_um FI_y_um Tn_Clathrate Tn_CO2 (s) Te Tm_Ice Tm_CO2 Tm_clathrate Th_CO2 Th_CO2_mode Th_LV Th_mode Density (g/cc) x(CO2) Mass% (NaCl)SGWS16-22 A 1 qtz ~2 1 LVC 20% 50% 30 10 -83.1 30.2 L dqtz ~2 2 LVC 20% 40% 20 20 -28.2 -89.7 -1.2 -57.3 9.6 30.4 L dqtz ~2 3 LVC 10% 40% 40 18 -30.1 -108.5 -21.3 -60.7 9.3 30.7 L 308.5 Lqtz ~2 4 LVC 20% 30% 30 30 -29.8 -106.7 9.2 30.6 L dqtz ~2 5 LVC 30% 30% 15 5 30.1 L 310.1 L2 Qtz ~2 1 LVC 20% 20% 12 20 -103 -21.3 -60.7 9.9 29.9 L 328 L 0.795533 0.282095Qtz ~2 2 LVC 40% 20% 15 10 -104.4 -60.9 9.7 30.1 L 300.8Qtz ~2 3 LVC 20% 40% 8 5 -106.3 -61 9.4 29.7 L dQtz ~2 4 LVC 20% 40% 4 4 -106.1 30 LQtz ~2 5 LVC 20% 40% 4 4 30.1 L 312.3 LQtz ~2 6 LVC 20% 40% 6 4 30 L 311.2 L3 Qtz ~2 1 LVC 30% 15% 8 8 -29.6 -86.5 -59.9 31.3 L 280.1 LQtz ~2 2 LVC 40% 10% 8 15 -59.9 9.5 31.6 L 318 L 0.300728 0.029938 0.624076Qtz ~2 3 LVC 20% 40% 15 10 -27.9 -96.9 -59.9 31.6 L 314.3 LQtz ~2 4 LVC 20% 40% 8 10 -102.6 -59.6 31.3 L 318.2 LQtz ~2 5 LVC 15% 40% 8 15 -29.5 -59.6 31.6 L 317.9 LA2 1 Qtz ~2 1 LVC 30% 35% 15 15 -29.6 -102.4 -60.1 9.3 29.7 L 311.5 L 0.811063 0.192426 1.012705Qtz ~2 2 LVC 20% 25% 15 15 -102.1 -60.1 9.3 30.3 L 318.1 LQtz ~2 3 LVC 15% 15% 15 10 -60.1 30.3 L 309.3 LQtz ~2 4 LVC 30% 25% 2 10 -60.1 29.9 L 311.4 L2 Qtz 1 5 LVC 20% 40% 8 4 -60.1 29.9 L 318.1 L3 Qtz 1 1 LVC 30% 30% 15 10 -30.3 -98.4 -59.8 9.8 30.4 L 303.5 L 0.788284 0.220096 0.038275Qtz 1 2 LVC 20% 20% 15 5 -30.3 -99.9 9.8 29.9 L 302.8 LQtz 1 3 LVC 20% 20% 5 5 31.6 L 308.1 L4 Qtz ~2 1 LVC 15% 25% 10 8 -28.6 -99.9 -58.5 9.6 30.3 L 325 LQtz ~2 2 LVC 15% 10% 8 8 -100.6 -58.5 9.6 29.2 L 325 LQtz ~2 3 LVC 10% 40% 6 8 -58.5 9.6 30.3 L 325 L 0.748281 0.291543 0.429409Qtz ~2 4 LVC 20% 25% 6 8 -58.6 30.4 LQtz ~2 5 LVC 20% 25% 8 8 -100.2 -58.5 30.3 L 325 LE1 1 Qtz ~2 1 LVC 20% 40% 7 2 -28.2 10.5 26.1 L 315.3 LQtz ~2 2 LVC 20% 30% 7 2 -28.2 -100.6 -59 10.5 26.1 L 315.3 L 0.931965 0.178363 0.E2 2 Qtz 2 1 LVC 20% 50% 7 5 -104.32 Qtz 2 2 LV 60% 7 52 Qtz 2 3 LV 50% 5 53 Qtz 2 4 LV 70% 7 5 -35.63 Qtz 2 5 LV 50% 7 5 -88E3 4 Qtz 2 1 LVC 20% 40% 15 15 -30 -97.8 -57.8 9.4 30.2 L 278 dQTZ 2 2 LVC 30% 50% 15 5 -30 -102.8 -57.8 9.4 29.5 L 278 dQTZ 2 3 LVC 30% 30% 10 10 -57.8 9.4 30.3 L 263.4 dQTZ 2 4 LVC 20% 35% 15 5 -30 -102.1 -57.8 8.5 27.7 L 278 dQTZ 2 5 LVC 30% 20% 15 8 -57.8 28.7 L 278 dQTZ 2 6 LVC 30% 20% 7 7 -57.8 9.4 278 dQTZ 2 7 LVC 30% 30% 7 7 -101.6 -57.8 9.4 28.7 L 278 d5 QTZ ~2 1 LVC 20% 20% 15 10 -28.7 -101.4 -58.6 9.4 29.3 L 328.5 LQTZ ~2 2 LVC 20% 30% 15 10 -28.7 -101.2 -58.6 8.5 29.5 L 322.3 LQTZ ~2 3 LVC 20% 20% 15 10 327.4 LQTZ ~2 4 LVC 25% 30% 20 15 -31.2 -99.5 -58.6 9.4 28.7 L 322.3 L 0.772911 0.304983 0.8187296 QTZ ~2 1 LVC 20% 20% 10 8 -28.7 -98.3 -58.1 9.3 28.9 L 343.2 L 0.730976 0.466296 0.818886QTZ ~2 2 LVC 20% 15% 15 8 -30.3 -98.9 -58.1 9.4 28.6 L 328.6 LQTZ ~2 3 LVC 10% 10% 10 10 -30.3 -98.9 -58.1 9.4 30.3 L 343.2 LSample ID FIA_Chip FIA_ID FIA_min FIA_pet FI_ID FI_Phases CO2_L fraction L- fraction FI_x_um FI_y_um Tn_Clathrate Tn_CO2 (s) Tm_CO2 Tm_clathrate Th_CO2 Th_CO2_mode Th_LV Th_mode Density (g/cc) x(CO2) Mass% (NaCl)BV22-93.70 B1 1 qtz ~2 1 LVC 25% 60% 15 15 -29.8 -103.4 -59.9 9.8 29.2 L dB1 qtz ~2 2 LVC 30% 60% 20 20 -30.1 -102.2 -59.9 9.3 28.9 L dB1 2 qtz ~2 1 LVC 30% 50% 30 10 -100.3 -59.0 9.6 29.7 L 307.8 L 0.804555 0.22886 0.429377B1 qtz ~2 2 LVC 25% 50% 10 5 -100.3 -59.0 9.6 29.3 L 299.9 LB1 qtz ~2 3 LVC 25% 55% 15 8 -100.3 -59.0 9.6 29.7 L 309.5 LB1 3 qtz ~2 1 LVC 30% 50% 8 5 -58.5 9.8 29.3 L 303.3 L 0.812153 0.23263 0.038055B1 qtz ~2 2 LVC 35% 65% 15 5 -30.0 -99.4 -58.5 9.8 29.1 L 294.9 LB1 4 qtz ~2 1 LVC 30% 55% 15 10 -101.1 -58.7 9.8 29.7 C 307.5 L 0.824989 0.19911 0.03803B1 qtz ~2 2 LVC 30% 55% 7 5 -101.1 -58.8 9.8 28.8 L 291.8 CB1 5 qtz ~2 1 LVC 35% 48% 30 10 -58.5 9.8 30.0 L 303.4 GB1 qtz ~2 2 LVC 35% 50% 15 10 -58.5 9.8 29.5 L 304.1 C 0.80877 0.23088 0.037968B1 6 qtz ~2 1 LVC 25% 60% 15 8 -31.5 -102.3 -58.3 9.4 30.1 L 312.2 L 0.836719 0.16873 0.818793B1 qtz ~2 2 LVC 20% 65% 20 8 -58.3 9.6 30.2 L 313.9 LB1 qtz ~2 3 LVC 20% 50% 10 5 -58.4 9.6 29.4 L 313.5 LB2 1 qtz 2 1 LVC 25% 50% 15 8 -59.6 9.8 29.4 L 317.1 GB2 qtz 2 2 LVC 30% 50% 15 15 -59.6 9.8 29.8 L 312.2 L 0.803123 0.22794 0.038244B2 qtz 2 3 LVC 25% 50% 8 8 -59.6 9.8 29.4 L 300.1 L 0.810494 0.23177 0.038012B2 qtz 2 4 LVC 25% 50% 10 5 -59.6 9.8 29.8 L 309.4 L  102          Appendix C: Digital Appendix attached as memory stick    

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