DOCSLIB.ORG

Geochemistry and Petrogenesis of the Mcelroy and Larder Lake Assemblages, Abitibi Greenstone Belt, Northeastern Ontario by Chris

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geochemistry and Petrogenesis of the Mcelroy and Larder Lake Assemblages, Abitibi Greenstone Belt, Northeastern Ontario by Chris Geochemistry and Petrogenesis of the McElroy and Larder Lake assemblages, Abitibi Greenstone Belt, Northeastern Ontario by Christopher T. Kimmerly, B.Sc. A Thesis submitted to the Department of Geological Sciences in partial fulfIllment of the requirements for the degree of Master of Science September 1992 Brock University St. Catharines, Ontario © Christopher T. Kimmerly, 1992 2 Abstract The McElroy and Larder Lake assemblages, located in the southern Abitibi Greenstone Belt are two late Archean metavolcanic sequences having markedly contrasting physical characteristics arid are separated from one another by a regional fault. An assemblage is an informal term which describes stratified volcanic and/or sedimentary rock units built during a specific time period in a similar depositional or volcanic setting and are commonly bounded by faults, unconformities or intrusions. The petrology and petrogenesis of these assemblages have been investigated to determine if a genetic link exists between the two adjacent assemblages. The McElroy assemblage is homoclinal sequence of evolved massive and pillowed fl.ows, which except for the basal unit represents a progressively fractionated volcanic pile. From the base to the top of the assemblage the lithologies include Fe-tholeiitic, dendritic flows; komatiite basaltic, ultramafic flows; Mg-tholeiitic, leucogabbro; Mg-tholeiitic, massive flows and Fe-tholeiitic, pillowed flows. Massive flows range from coarse grained to aphanitic and are commonly plagioclase glomerophyric. The Larder Lake assemblage consists of komatiitic, Mg-rich and Fe-rich tholeiitic basalts, structurally disrupted by folds and faults. Tholeiitic rocks in the Larder Lake assemblage range from aphanitic to coarse grained massive and pillowed flows. Komatiitic flows contain both spinifex and massive textures. Geochemical variability within both assemblages is attributed to different petrogenetic histories. The lithologies of the McElroy assemblage were derived by partial melting of a primitive mantle source followed by various degrees of crystal fractionation. Partial melting of a primitive mantle source generated the ultramafic flows and possibly other flows in the assemblage. Fractionation of ultramafic flows may have also produced the more evolved McElroy lithologies. The highly evolved, basal, dendritic flow may represent the upper unit 3 of a missing volcanic pile in which continued magmatism generated the remaining McElroy lithologies. Alternatively, the dendritic flows may represent a primary lava derived from a low degree (10-15%) partial melt of a primitive mantle source which was followed by continued partial melting to generate the ultramafic flows. The Larder Lake lithologies were derived by partial melting of a komatiitic source followed by gabbroic fractionation. The tectonic environment for both assemblages is interpreted to be an oceanic arc setting. The McElroy assemblage lavas were generated in a mature back arc setting whereas the Larder Lake lithologies were produced during the early stages of komatiitc crust subduction. This setting is consistent with previous models involving plate tectonic processes for the generation of other metavolcanic assemblages in the Abitibi Greenstone Belt. 4 Ackowledgements I would to thank Dr. Greg Finn for supervising, supporting and showing patience while this thesis developed. I benefited greatly from discussions and suggestions with Dr. Wayne Jolly and Dr. Frank Fueten. Dr. Steve Jackson of the Ontario Geological Survey initially suggested that studying rocks in the Larder Lake area could be a good project (and he was right). His suggestions and discussions were also valuable. Lori Wilkinson, Seppo Kakko, Elaine Lau, in 1990, and Mike Johnston, in 1991, helped in the field and made bashing through the bush a little more bearable. Dan Redmond, co-founder of the Precambrian Think-Tank, was a great office partner. Mike Lozon was very helpful when it came to advice in the generation of figures (especially with AutoCAD). Candy Kramer produced good thin sections. Geochemical analyses were conducted at the OGS Geoscience Laboratories and the Memorial University of Newfoundland. Financial support from an Ontario Graduate Scholarship in 1991 and an N.S.E.R.C. scholarship in 1992 is greatfully acknowledged. A Lithoprobe grant supported field expenses in 1992. Finally, many thanks go to my family for their support and understanding. 5 Table. of Contents Page Abstract ... 2 Acknowledgements .. .4 Table of Contents ... 5 List of Figures ... 7 List of Tables ... 8 List of Appendices ... 8 Chapter 1: Introduction ... 9 1.1 Introduction ... 9 1.2 Regional Geology ... 9 1.3 Larder Lake Group ... 14 1.4 Purpose of Study ... 16 1.5 Location and Access ... 16 1.6 Previous Work ... 17 1.6.1 Field Studies ... 17 1.6.2 Petrogenetic Studies ... 18 Chapter 2: Local Geology ... 20 2.1 McElroy assemblage ... 20 2.1.1 Introduction ... 20 2.1.2 Dendritic flows ... 23 2.1.3 Leucogabbro ... 28 2.1.4 Ultramafic flows ... 28 2.1.5 Intermediate to felsic volcaniclastic rocks ... 30 2.1.6 Medium to coarse grained flows ... 32 2.1.7 Aphanitic to fine grained flows ... 34 2.2 Assemblage Boundaries ... 36 2.2.1 Lincoln Nipissing Peridotite ... 36 2.2.2 Lincoln Nipissing Shear Zone ... 37 2.2.3 Boston Creek Fault ... 39 2.2.4 Skead assemblage .. .39 2.2.5 Huronian sedimentary rocks ... 39 2.3 Larder Lake assemblage ... 39 2.4 Summary .. .44 Chapter 3: Geochemistry of the McElroy and Larder Lake assemblages .. .49 3.1 Introduction .. .49 3.1.1 Purpose of Geochemical Study .. .49 3.1.2 Methods .. .49 3.1.3 Sample Selection ... 57 3.2 Alteration ... 58 3.2.1 Introduction ... 58 3.2.2 Major Element Alteration ... 60 3.2.3 Trace Element Alteration ... 67 6 3.3 Classification of the McElroy and Larder Lake assemblages ... 69 3.3.1 Major Elements ... 69 3.3.2 Trace Elements ... 73 3.3.3 Rare Earth Elements ... 76 Chapter 4: Geochemical Variations ... 79 4.1 Introduction ... 79 4.2 Major Element Variation ... 80 . 4.3 Trace Element Variation ... 85 4.4 Molecular Proportion Ratios ... 88 4.5 Discussion ... 90 4.6 Summary ... 91 Chapter 5: Generation of McElroy and Larder Lake assemblages ... 94 5.1 Introduction ... 94 5.2 Magma Genesis in the Kirkland Lake Area ... 94 5.3 Magma Genesis in the McElroy and Larder Lake assemblages ... 96 5.3.1 Introduction ... 96 5.3.2 Partial Melting Modelling ... 99 5.3.3 Crystal Fractionation Modelling ... 105 5.3.4 Crustal Contamination ... 114 5.3.5 Summary ... 116 Chapter 6: Comparison with Phanerozoic Rocks of Known Tectonic Settings ... 118 6.1 Introduction ... 118 6.2 Discriminant Diagrams ... 119 6.3 Tectonic Setting of McElroy and Larder Lake assemblages ... 119 Chapter 7: Discussion ... 124 7.1 Discussion ... 124 7.2 Archean Heat Flow and Tectonics ... 127 Chapter 8: Conclusions ... 129 References ... 131 Appendices ... 138 7 List of Figures 1-1 Location map of Abitibi Subprovince within the Superior Province. 1-2 Regional geology of the Kirkland Lake-Larder Lake area. 1-3 Photomicrograph of section from the Lincoln Nipissing Shear Zone. 2-1 Geological map of the McElroy assemblage. 2-2 Simplified cross-section of SW portion of McElroy assemblage. 2-3 Outcrop photograph of dendritic flow displaying spinifex-type texture. 2-4 Photomicrograph of dendritic flow showing preferred orientation of actinolite. 2-5 Outcrop photograph of randomly oriented dendritic flow. 2-6 Photomicrograph of random orientation within the denritic flow. 2-7 Photomicrograph of leucogabbro. 2-8 Photomicrograph of ultramafic flow. 2-9 Photomicrograph of intermediate crystal tuff. 2-10 Field photograph of intermediate tuff breccia. 2-11 Plagioclase phenocrysts in a coarse grained flow with knobby gabbroic texture. 2-12 Gradational contact between aphanitic flow and medium grained flow from McElroy assemblage. 2-13 Pillowed flow within McElroy assemblage. 2-14 Plagioclase glomerophyric texture in fme to medium grained massive flow. 2-15 Polygonal jointing in Lincoln Nipissing Peridotite. 2-16 Photomicrograph of Lincoln Nipissing Peridotite. 2-17 Deformed contact between intermediate and mafic rocks. 2-18 Undeformed contact between intermediate and mafic lithologies. 2-19 Geological map of Larder Lake assemblage distribution. 2-20 Slightly deformed pillowed flow from Larder Lake assemblage. 2-21 Spinifex textured komatiite from Larder Lake assemblage. 2-22 Syenite intruding massive mafic volcanic in northwest portion of McElroy assemblage. 2-23 Epidote veining in medium grained massive flow. 3-1 Location map for geochemical samples from the McElroy assemblage. 3-2 Variation plot between AlZ0 3 and TiOz. 3-3 Molecular ratio plots for major and trace elements of McElroy and Larder Lake assemblage. 3-4 Tholeiitic/calc-alkaline discriminant plots for tholeiitic units in the Larder Lake area. 3-5 Lithologic discriminant plots for the tholeiitic units in the Larder Lake area. 3-6 Jensen Cation Plots for tholeiitic units in the Larder Lake area. 3-7 Chondrite normalized extended trace element plots for tholeiitic units in the Larder Lake area. 3-8 Chondrite normalized rare earth element plots for the tholeiitic units in the Larder Lake area. 3-9 High field strength and rare earth element patterns for the McElroy and Larder Lake assemblages. 4-1 Mg#-major oxide variation diagrams for McElroy and Larder Lake assemblages. 4-2 Zr-major oxide variation diagrams for the McElroy and Larder Lake assemblages. 4-3 Mg#-trace element variation diagrams for the McElroy and Larder Lake assemblages. 4-4 Zr-trace element variation diagrams for the McElroy and Larder Lake assemblages. 4-5 Molecular proportion ratios for McElroy and Larder Lake assemblages. 4-6 Contact between dendritic and massive flow. 8 5-1 Elemental variation in the Larder Lake and McElroy assemblages with respect to chondrite data. 5-2 Results of partial melting calculations of McElroy assemblage from a primitive mantle source. 5-3 Results of partial melting calculations of Larder Lake assemblages from a primitive mantle source. 5-4 Results of partial melting calculations of McElroy assemblage from a komatiitic source.
Load more

Recommended publications
  • Teddy's Falls Waterpower Project
    OEL-HYDROSYS TEDDY’S FALLS WATERPOWER PROJECT PROJECT DESCRIPTION CANADIAN ENVIRONMENTAL ASSESSMENT ACT CLASS ENVIRONMENTAL ASSESSMENT FOR WATERPOWER PROJECTS PREPARED FOR: WENDIGO POWER PARTNERSHIP INC. 9094 CAVANAGH ROAD ASHTON, ONTARIO K0A 1B0 PREPARED BY: OEL-HYDROSYS INC. 3108 CARP ROAD, BOX 430 OTTAWA, ONTARIO K0A 1L0 MARCH 2012 TEDDY’S FALLS WATERPOWER PROJECT PROJECT DESCRIPTION CANADIAN ENVIRONMENTAL ASSESSMENT ACT CLASS ENVIRONMENTAL ASSESSMENT FOR WATERPOWER PROJECTS Prepared for: WENDIGO POWER PARTNERSHIP INC. 9094 Cavanagh Road Ashton, Ontario K0A 1B0 Prepared by: OEL-HYDROSYS INC. 3108 Carp Road, Box 430 Ottawa, Ontario K0A 1L0 File No. OE9580 March 2012 Ref: OE9580 Teddy’s Falls Waterpower Project Description March2012 Teddy’s Falls Waterpower - Project Description TABLE OF CONTENTS 1. INTRODUCTION ............................................................................................................ 1 1.1. Distribution .................................................................................................................. 2 1.2. Contact Information ..................................................................................................... 3 2. PROJECT INFORMATION ............................................................................................... 4 2.1. Project Area .................................................................................................................. 4 2.2. Project Location...........................................................................................................
    [Show full text]
  • 219819Fre.Pdf
    I I I I Le Programme federal des ports constitues en societe, les adminis­ Urgences pour petits bateaux trations portuaires sont dirigees par des Generatites : Plus de 2 200 ports pour petits bateaux personnes nommees par les groupes Centre de coordination des secours qui desservent une multitude de de pecheurs ou les collectivites. (Trenton) 1-800-267-7270 bateaux de peche commerciale, de En vertu d'une entente de cinq (Secours Air-Mer) - 24 heures sur 24 plaisance et autres, d'un ocean a l'autre, ans, ces administrations assument 1-613-267-7270 jouent un role vital dans la vie l'entretien courant de leurs ports. De pastes 3870 et 3875 economique et sociale du Canada. plus, elles etablissent et pergoivent les La responsabilite de l'entretien frais de location et les droits de permis Transport maritime - Situations permanent et de !'exploitation et d'amarrage. Ces recettes servent a d'urgence et Centre d'intervention en quotidienne de ces ports incombe au exploiter le port, a apporter certains cas de deversement (416) 268-6060 ministere federal des Peches et des niveaux precis de reparations et a Radio-urgence - Canal 16 156,80 kHz Oceans dans le cadre de son embaucher un responsable de port. Les Programme des ports pour petits projets d'entretien trop coOteux ou MAFORS (Meteo et changements pour bateaux (PPB). complexes pour !'administration la navigation) Canal 21 161 ,64 kHz Qu'il soit grand ou petit, un port est portuaire sont entrepris par les PPB . traditionnellement le centre d'activite Les ports geres par des adminis­ Les bateaux de sauvetage de la ainsi que l'assise economique de la trations portuaires ont la priorite pour ce Garde·cotiere plupart des collectivites de peche qui est du Programme des ports pour (du 24 mai au I er septembre) c6tieres.
    [Show full text]
  • The Timiskaming Series of the Kirktand Iake Area
    THE TIMISKAMINGSERIES OF THE KIRKTANDIAKE AREA D. F. HEWITT Ontar'i,oDepartment of Mines, Toronto, Canadn' AestRAcr This paper presents a study of the stratigraphy, sedimentation and structure of the Timiskaming 3eries of the Kirkland Lake area, northeastern Ontario, It is suggested that this seclion be defined as the type section for the Timiskaming Series in Ontario. Interpretations of the geologic history of the epoch, the nature of the provenance area suppiyiog sediments and the character and environment of deposition of the sediments are given. Tle sediments south of the major Larder Lake break are tentatively correlated with the sediments in the belt to the north of the break as Timiskaming in age, on the basis of detailed structural studies in Skead and Hearst townships. Evidence in Ontario and Quebec shows conclusively that the Keewatin and Timiskaming se-riesof the Kirklind-Larder-Noranda area are separated by a major structural unconformity. Examination of the Timiskaming rocks discloses that the provenance area was composed of basic volcanics and intrusives, rhyolites and acid porphyries of great jasper greywackes, variety, minor amounts of chert, iron formation, an! llaty and rare syenite, granite and gneiss. Disintegration of the rocks of the area was largely mech- anical. fhu Ti-irkJ-ing sedimentation represents a distinctive magna facies of eugeosynclinalenvironment. INtnooucrroN The Timiskaming rocks of the Kirkland Lake-Larder Lake area form a belt extending for 36 miles in length, from Eby township on the q/est, through the townships of Grenfell, Teck, Lebel, Gauthier, McVittie and McGarry, to the Quebec boundary on the east. To the west, in Eby township, the Timiskaming Seriespass underneath the Cobalt Series;to the east, the sediments again pass beneath the Cobalt sediments uear Cheminis Station on the Quebecboundary.
    [Show full text]
  • Inland Ontario Lakes Designated for Lake Trout Management
    Inland Ontario Lakes Designated for Lake Trout Management July 2015 . ISBN 978-1-4606-6257-1 (PDF) Fisheries Section Species Conservation Policy Branch Ontario Ministry of Natural Resources and Forestry P.O. Box 7000, 300 Water Street Peterborough, ON K9J 8M5 “A prerequisite to the effective management of a resource is a knowledge of the distribution and magnitude of that resource.” Introductory sentence from “The Distribution and Characteristics of Ontario Lake Trout Lakes” (Martin and Olver 1976). ii Abstract Lake Trout lakes are rare. Only about one percent of Ontario’s lakes contain Lake Trout, but this represents 20-25% of all Lake Trout lakes in the world. The province, therefore, has a great responsibility to manage them wisely. OMNRF efforts to develop a coordinated strategy to protect Lake Trout populations in Ontario requires a comprehensive list of lakes currently designated for Lake Trout management. This report lists the inland Ontario lakes (exclusive of the Great Lakes) that are currently designated for Lake Trout management. In addition, the list classifies the lakes as to whether they are to be managed for naturally reproducing populations (‘Natural’ lakes) or as put-grow-take (‘P-G-T’) lakes. ‘Natural’ lakes include those lakes that may have lost populations but have been identified for rehabilitation. ‘P-G-T’ lakes are managed to provide recreational fishing opportunities and/or to direct angling effort away from more sensitive ‘Natural’ lakes. OMNRF policies or guidelines may be applied differently depending on the lake classification, or in other cases may be applied to both classifications in a similar manner.
    [Show full text]
  • L. Timiskaming Rift Valley
    THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use. Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”).
    [Show full text]