Stratigraphy, Geochemistry, Isotopic Signatures and VMS Potential of Late Archean Volcanic Rocks from the Southern Slave Craton, Northwest Territories – Regional Comparison to Sharrie Lake and Turnback Lake Volcanic Belts by Alexandra J. Berger A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Science in Earth Sciences Carleton University Ottawa, Ontario © 2015 Alexandra J. Berger Abstract Neoarchean metavolcanic belts in the Slave craton, Northwest Territories, Canada, overlay a Paleo- to Mesoarchean granite-gneiss complex and its Mesoarchean volcano-sedimentary cover. The ca. 2.70 Ga Kam Group and ca. 2.66 Ga Banting Group volcanic stratigraphy, as defined in the Yellowknife volcanic belt, has been applied to describe all volcanic belts in the Slave craton and is based primarily on geochemical signatures. Recent geochemistry, age data, and Nd-isotopic analyses support distinct volcanic episodes occurring intermittent to Kam volcanism and Banting volcanism. Geochemical and isotopic similarities exist amongst mafic and intermediate volcanic rocks, whereas two distinct geochemical signatures define felsic volcanic rocks. Evidence at Sharrie and Turnback volcanic belts supports magma emplacement in a rift system with an evolving, heterogeneous source. Finally, Archean volcanic belts are known for housing VMS deposits and the Slave craton volcanic belts show potential for hosting base-metal deposits. ii Acknowledgments This project has benefitted from the support and experience of many people. I extend my gratitude to my supervisor, Dr. Brian Cousens, for the opportunity to work with him on this exciting project and for sharing his passion for geology. I would also like to thank Luke Ootes from the Northwest Territories Geoscience Office for acting as my co-supervisor and for organizing the field work and aiding with the interpretations and edits. Financial and ground assistance was provided by the Ontario Graduate Scholarship and Carleton University’s internal scholarships. Additional funding was provided by Dr. Brian Cousens’ research grants from the Northwest Territories Geoscience Office and the Department of Indian and Northern Affairs, Polar Continental Shelf Program, and Aurora Geosciences Ltd. The field seasons and sample collecting would not have been possible (and a lot less enjoyable) without Val Jackson’s guidance and years of experience mapping Archean greenstone belts. Her keen eye for detail and calm demeanor in the field has encouraged me to strive for similar. I thank Ben Williams for being my traverse partner and for all the imaginative and entertaining conversations. I would like to thank all of my colleagues in graduate studies at Carleton University for making these past years very memorable. Timothy Mount and Mike Jackson of Carleton University were of tremendous help with sample preparations. Guidance and support in the isotope lab and with the TIMS was provided by Shuangquan Zhang. It has been a pleasure collaborating, supporting and sharing in good times with my fellow graduate students while we strive for common goals. iii Finally, I would like to acknowledge those whom I hold most closely. I thank my parents, Ben and Linda Berger, for their perpetual patience and support throughout the course of my studies and their invaluable guidance when I needed it most. I am grateful for my brother, Eric, who has opened my eyes to life outside of school and for sharing in my love of science. Lastly, I am indebted to Rémy Poulin for being by my side every step of the way, for holding my hand through the darkest tunnels, and for lifting me even higher in times of celebration. iv Table of Contents Abstract ……………………………………………………………………………..…...ii Acknowledgements ...…………………………………………………………….....iii Table of Contents ...………………………………………………………………………..v List of Tables ……………………………………………………………………...….ix List of Figures ………………………………………………………………….......…..x List of Appendices ………………………………………………………………………..xiii Chapter 1: Introduction .………………….……………………………………………...1 Chapter 2: Regional Geology ..………………………………………………………...3 2.1 Regional Geology: Overview ...………………………………………………..3 2.2 Deformation and Metamorphism .…………………………………………5 2.3 Mineralization ………………………………………………………………….6 2.4 Craton Formation: Previous Work ...………………………………………..7 Chapter 3: Local Geology – Cameron-Beaulieu Area ……………………...…10 3.1 Cameron-Beaulieu Volcanic Belts: Overview ………………………...10 Chapter 4: Analytical Methods and Techniques ………………………………...16 4.1 Sample Collection ………………………………………………………...16 4.2 Sample Preparation ………………………………………………………...17 4.3 Geochemical Analysis: XRF, ICP-MS and ICP-AES ………………...17 4.4 Isotopic Analysis: Sm-Nd ………………………………………………...18 4.5 Accuracy and Reproducibility ………………………………………………...20 4.6 Errors in Geochemical Analysis ………………………………………...21 Chapter 5: Lithological Descriptions and Petrography ………………………...25 v 5.1 Lithology Overview ………………………………………………………...25 5.2 Mafic Rocks …………………………………………………………….…..26 5.2.1 Field Observations …………………………………………….…..26 5.2.2 Petrography ………………………………………………….……..28 5.3 Felsic Rocks ………………………………………………………….……..31 5.3.1 Field Observations ………………………………………….……..31 5.3.2 Petrography …………………………………………………….…..32 5.4 Intermediate Rocks …………………………………………………….…..36 5.4.1 Field Observations …………………………………………….…..36 5.4.2 Petrography …………………………………………………….…..38 5.5 Sedimentary Rocks ………………………………………………………...40 5.6 Unit Relationships and Contacts at Sharrie and Turnback Lakes ………...41 5.7 Metamorphism and Alteration ………………………………………………...42 Chapter 6: Results – Geochemistry of Major Oxides and Trace Elements ...48 6.1 Regional and Sharrie and Turnback Datasets ………………………...48 6.2 Geochemistry of Major Oxides ………………………………………...49 6.2.1 Regional Dataset …………………………………………….…..49 6.2.2 Sharrie and Turnback Dataset …………………………….…..53 6.3 Geochemistry of Trace and Rare Earth Elements …………………….…..56 6.3.1 Regional Dataset …………………………………………….…..56 6.3.2 Sharrie and Turnback Dataset …………………………….…..60 6.4 Regional Dataset versus Sharrie and Turnback Dataset …………….…..64 Chapter 7: Sm-Nd Isotopic Analysis …………………………………………….…..66 vi 7.1 Sm-Nd Isotope System ………………………………………………………..66 7.2 Regional Sm-Nd Isotopic Results ……………………………………......66 7.3 Sharrie and Turnback Sm-Nd Isotopic Results ……………………..…70 7.4 Regional versus Sharrie and Turnback Datasets ……………………..…78 Chapter 8: Discussion and Interpretations ……………………………………..…80 8.1 Regional Volcanic Petrogenesis ……………………………………..…81 8.1.1 Regional Mafic Volcanic Rocks: Classification and Origin ....81 8.1.2 Regional Intermediate Volcanic Rocks: Classification and Origin ……………………………………………………………......90 8.1.3 Felsic Volcanic Rocks: Classification and Origin ……………..…91 8.2 Sharrie and Turnback Lakes Petrogenesis ……………………………......95 8.2.1 Sharrie and Turnback Mafic Volcanic Rocks: Classification and Origin ………..…………………………………………………..…..95 8.2.2 Sharrie Intermediate Volcanic Rocks: Classification and Origin ……….…………………………………………………………..…..105 8.2.3 Sharrie and Turnback Felsic Volcanic Rocks: Classification and Origin ………….……………………………………………………110 Chapter 9: VMS Prospects – Comparison of Known Deposits to Sharrie And Turnback Belts …………………………………………………….....117 9.1 VMS Potential: Craton-Wide Outlook in the Northwest Territories …....118 9.2 VMS Potential: Sharrie and Turnback Lakes …………………….....125 9.3 Sharrie and Turnback VMS Potential versus Known VMS Deposits ….130 9.3.1 Sharrie and Turnback versus Sunrise and Bear Deposits.……..132 vii 9.3.2 Sharrie and Turnback versus BB Deposit ………………………134 9.3.3 Sharrie and Turnback versus Hood Deposits ………………135 9.3.4 Sharrie and Turnback versus Val D’Or, Quebec ………………136 9.4 Summary ………………………………………………………………………138 Chapter 10: Conclusions ………………………………………………………139 Appendices ………………………………………………………………………………144 References ………………………………………………………………………………184 viii List of Tables Table 8.1 Fractional crystallization calculations for hornblende and apatite …..…106 ix List of Figures Figure 2.1: Geologic map of the Slave craton and sample locations …………..…..9 Figure 3.1: Geologic map of the Cameron-Beaulieu volcanic belts and subareas ……………………………………………………………………………..13 Figure 3.2: Geologic map of the Sharrie Lake volcanic belt …………………..…14 Figure 3.3: Geologic map of the Turnback Lake volcanic belt …………………..…15 Figure 4.1: Internal standard 10-LT-05 results from ALS and OGS labs ....…..23 Figure 4.2: Internal standard 99-YK-2 results from ALS and OGS labs ……..24 Figure 5.1: Volcanic rocks from greenstone belts in the southern Slave craton….46 Figure 5.2: Thin section pictures of volcanic rocks in the Slave craton …..…47 Figure 6.1: Rock discrimination diagrams for the regional collection and the Sharrie and Turnback collections ……………………………………………….….....50 Figure 6.2: Zr vs. La for mafic, intermediate and felsic volcanic rocks from the regional and Sharrie and Turnback datasets …………………………......51 Figure 6.3: Magmatic affinities for mafic, intermediate and felsic volcanic rocks from the regional and Sharrie and Turnback datasets ………………………..........51 Figure 6.4: Harker diagrams for major oxides versus SiO2 wt. % for regional and Sharrie and Turnback samples ……………………………………………………..54 Figure 6.5: Chondrite and primitive mantle normalized multi-element plots for regional data ……………………………………………………………………….….....59 Figure 6.6: Slope quantification using La/Sm (cn) vs. Dy/Yb (cn) for regional, Sharrie and Turnback mafic volcanic rocks ……………………………………….….....60 Figure 6.7: Chondrite and primitive