RHYOLITES OF THE TEMAGAMI GREENSTONE BELT, ONTARIO PETROLOGY AND GEOCHEMISTRY OF FELSIC VOLCANICLASTIC ROCKS ALONG THE SHERMAN MINE ROAD, TEMAGAMI GREENSTONE BELT, STRATHY TOWNSHIP, ONTARIO. By TIMOTHY CHARLES SCHWARTZ, B.Sc. (Hons) A Thesis Submitted to the School of Graduate Studies in Partial Fulfilment ofthe Requirements for the Degree Master of Science McMaster University (c) Copyright by Timothy Charles Schwartz, March 199 5 MASTER OF SCIENCE ( 1995) McMASTER UNIVERSITY (Geology) Hamilton, Ontario TITLE: Petrology and Geochemistry ofFelsic Volcaniclastic Rocks along the Sherman Mine Road, Temagami Greenstone Belt, Strathy Township, Ontario AUTHOR: Timothy Charles Schwartz, B.Sc. (Honours) (University ofManitoba) B.Sc. (University ofWinnipeg) SUPERVISOR: Dr. J.H. Crocket NUMBER OF PAGES xiii, 180 II ABSTRACT Felsic volcaniclastic rocks and intrusions along the Sherman Mine road, Temagami greenstone belt, were studied to determine if the petrological and chemical characteristics of these rocks indicate they are favourable hosts for volcanogenic massive sulphide deposits. Mapping of these felsic rocks was done at a scale of 1:5000 utilizing a lOOm spaced cut grid and pace and compass. Since outcrop is scarce and exposures are poor in this area, most correlation of the felsic horizons was done on the basis of trace and rare­ earth element geochemistry. On the basis of the chemistry of the rocks, three distinct felsic horizons were defined. The quartz feldspar porphyries are FI type calc-alkaline felsic intrusives with [La/Yb ln ratio from 16 to 29 and no Eu anomaly. The Link Lake and Sherman Gate horizons are a FII type calc-alkaline volcaniclastic horizon with [La/Yb] 11 ratio from 5 to 7 and weak negative to positive Eu anomalies. The Upper and Lower Felsic horizons are Filla type tholeiitic rhyolite lava flows and volcaniclastics. These horizons have [La/Yb ]0 ratios from 1 to 3 and strong negative Eu anomalies from 0.16 to 0.42. Petrology and net transfer of material calculations indicate the Upper and Lower Felsic Horizons have been silicified, resulting in a net addition of Si and AI to these rocks. There is no distinct pattern of chemical changes which would indicate proximity to a single volcanogenic massive sulphide alteration pipe, however, an enrichment of the light rare­ earth elements in the eastern section of the thesis area suggests this area maybe more proximal to an alteration pipe, and thus a vent. Lithological characteristics of the eastern section of the thesis area also suggests it is more proximal to a vent than the western section. Pyrite clasts are present in several of the volcaniclastic units. While the presence of sulphide rich clasts can be an indicator of proximity to a volcanogenic massive sulphide deposit, the textural and chemical characteristics of these clasts indicate they originated from shale horizons in this area. For this reason, these clasts should not be used as an indicator of proximity to a volcanogenic massive sulphide deposit. Trace and rare-earth element classifications indicate both the Link Lake and Sherman Gate horizons, and the Upper and Lower Felsic horizons are favourable host rocks for volcanogenic massive sulphide style mineralization while the quartz feldspar porphyries, such as the Milne vent and City Dump vent, are not. Although the felsic volcanic packages are relatively thin, potential exploration targets would be the upper contact of the Upper Felsic horizon and the Link Lake and Sherman Gate horizons. Acknowledgements I express my greatest thanks to Dr. J.H. Crocket for taking me on as a graduate student, and providing a basis for increasing my knowledge on the theories of the formation of VMS deposits, and the principle litho geochemical techniques used to explore for them. Maybe next time we will actually find a mine. My sincere thanks goes to Mark, Richard, Jodie, Cam, Dave and Trev for the coffee and constructive conversation breaks. To Steve Zymela, Lens Zwicker and Jack Whorwood, thanks for the computer programs, thin sections and photographic work respectively. Thanks to Dr. Geoff Orton for the help with the volcanology and Dr. Bob Bowins for the ICP analyses. A special thanks to Kathy, for helping me with field work, for being so patient, for your encouragement and your acceptance of my proposal of marriage. Finally I would like to acknowledge the financial support, given through Dr. J.H. Crocket, from the Natural Sciences and Engineering Research Council (NSERC) Research Grant. v TABLE OF CONTENTS Page Abstract ............................................................................................... iii Acknowledgements .............................................................................. v Table of Contents ................................................................................. vi List of Figures ...................................................................................... xi List ofTables ....................................................................................... xii List of Photographic Plates ................................................................... xii CHAPTER 1: INTRODUCTION ........................................................... 1 1.1 Location and Accessibility ...................................................................... 1 1.2 Historical Background ............................................................................ 1 1.3 Previous Work ....................................................................................... 3 1.3 .1 Government projects ........................................................................ 3 1.3.2 Academic studies .............................................................................. 3 1.3.3 Exploration activity .......................................................................... 3 1.4 Objective and Thesis ............................................................................... 4 CHAPTER 2: METHODOLOGY .......................................................... 5 2.1 Field Approach ....................................................................................... 5 2.2 Petrology ............................................................................................... 7 2.3 Geochemistry ......................................................................................... 7 2.3.1 Preparation ....................................................................................... 7 2.3.2 XRF ................................................................................................. 7 2.3.2.1 Major oxide analysis ................................................................... 8 2.3.2.2 Trace element analysis ................................................................ 9 2.3.2.3 Trace element analysis: McMaster University ............................ 10 2.3.3 INAA ............................................................................................. 10 VI Page CHAPTER 3: GENERAL GEOLOGY. ................................................ 14 3 .1 Regional Setting ................................................................................... 14 3.2 Regional Structures .............................................................................. 16 3.3 Age of the Temagami Greenstone Belt ................................................. 17 3.4 Local Geology ...................................................................................... 18 3.4.1 General geology ............................................................................. 18 3.4.2 Local structure ............................................................................... 17 3.4.3 Outcrop exposure ........................................................................... 20 CHAPTER 4: PETROLOGY ............................................................... 23 4.1 Nomenclature ....................................................................................... 23 4.2 Mafic Metavolcanics ............................................................................. 24 4.2.1 Tholeiitic flows: Unit 1 ................................................................... 24 4.2.2 Calc-alkaline flows: Unit 2 .............................................................. 25 4.3 Mafic To Ultramafic Intrusives ............................................................. 26 4.3.1 Gabbro, diorite: Unit 6 .................................................................... 26 4.3.2 Diabase: Unit 10 ............................................................................. 27 4.4 Felsic Metavolcanics ............................................................................. 28 4.4.1 Introduction .................................................................................... 28 4.4.2 Lower Felsic horizon: Unit 3 .......................................................... 28 4.4.2.1 Garbage Dump trench ............................................................... 29 4.4.2.2 Hydro Station trench ................................................................. 34 4.4.2.3 Fold Nose trench ...................................................................... 39 4.4.3 Upper Felsic horizon: Unit 3 ........................................................... 39 4.4.3.1 Mineralogy ............................................................................... 45 4.4.4 Link Lake and Sherman Gate horizons: Unit 4 ................................ 47 4.5 Quartz Feldspar Porphyry: Unit 4f.. .....................................................