Theses Digitisation: This Is a Digitised

https://theses.gla.ac.uk/ Theses Digitisation: https://www.gla.ac.uk/myglasgow/research/enlighten/theses/digitisation/ This is a digitised version of the original print thesis. Copyright and moral rights for this work are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Enlighten: Theses https://theses.gla.ac.uk/ [email protected] The origin, nature and tectonic significance of the Hallinmaki Cu-deposit, Virtasalmi District, South-central Finland Kenneth Campbell Lawrie Thesis submitted for the degree of Doctor of Philosophy Department of Geology, University of Glasgow July 1987 ProQuest Number: 10662770 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Pro ProQuest 10662770 Published by ProQuest LLC(2017). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 GLASGOW " Tl UNIVERSITY [ l ib r a r y j Acknowledgements This research was carried out during the tenureship of a Glasgow University Postgraduate Scholarship Award from 1981-1984, the receipt of which is gratefully acknowledged. Outokumpu Oy. of Finland provided considerable and invaluable logistical support during my field seasons, for which I thank them. I am particularly grateful for the fullest cooperation I was afforded by the staff at Hallinmaki Mine, who went out of their way to make me feel at home. Heikki Saarnio, geologist at Kotalahti Mine is also thanked for his hospitality, The field staff of Outokumpu's Exploration Division, who were based in Virtasalmi, particularly Marti Tumanto and Jorma Suvanto and their wives as well as Heikki Pustijarvi, Jukka Jokela, Timo Heino and Helena Viita are thanked for their friendship and making my stay in Finland so enjoyable. Dr. Tapio Koistinen is similarly thanked for his hospitality and comments in the field. ' I wish to express my appreciation to my supervisor, Professor D. R. Bowes, for his support, encouragement and critical comments in the field and on this manuscript. The technical staff at the Geology Department in Glasgow University, and in particular Mr Roddy Morrison and Mrs Betty Mackenzie are thanked for their friendly, willing and capable assistance. I am indebted to Douglas McLean for his help in preparation of all photographic material. Drs. A. F. Park, P. Ward and K. A. S. Davidson and Mr G. Waller are thanked for useful discussions, and, together with Drs. C. J. Burton, D. S. Weedon and Janey MacDougall, are thanked for their help and friendship. I particularly want to thank my parents for their unstinting support and encouragement, for which no words here are adequate. To my wife Helen, who from both near and afar has had to put up with the rocks of the Virtasalmi District for so long, who has helped discuss my ideas before I put them to paper, and then retyped them several times, and who has never questioned my need to complete this work, I offer my deepest thanks. ii CONTENTS Page No, Acknowledgements 1 Contents ii Abstract vii SECTION 1 : Introduction and rock types PART 1 : Introduction 1.1.1 Regional geological setting 1. 1.2 Previous work in the study area and initial aims of this project 1.1.3 Scope and organisation of the Thesis 10 1.1.4 Terrain 12 PART 2 : Lithologies 13 1. 2.1 General lithology distribution 13 1. 2.2 Pre-D^ lithological assemblage : 15 petrography and field relationships (i) Amphibolites 15 (a) Introduction 15 (b) Petrography 16 (c) Pillow lavas-lava tubes 19 (d) Banded amphibolites 23 (ii) Marbles and calc-silicate (skarn) 26 lithologies 26 (a) Marbles 28 (b) Calc-silicate skarns 30 (1) Type I 31 (2) Type II 32 (3) Type III 33 (4) Type IV 33 (5) Type V 34 (6) Type VI 35 (7) Type VII 35 (8) Type VIII O '') Q\xalW .ojKakAt>pcd:Vvi'C. ckUts cu\A <y\e (V) OtW r UtWaVo qies iii Page No. SECTION 2 : Structural, igneous and metamorphlc features PART 1 : Structural development of the Virtasalmi 37 District 2.1.1 Introduction 37 2. 1.2 Major structural features 38 2.1.3 Structural sequence 41 2.1.4 Lithological layering (Sq ) 42 2.1.5 First phase of deformation (D^) 43 2. 1.6 Second phase of deformation (D2) 45 2.1.7 Third phase of deformation (D„) 52 3 2.1.8 Fourth phase of deformation (D^) 54 2.1.9 Fifth phase of deformation (D^) 55 2.1.10 Sixth phase of deformation (D,) 56 o 2.1.11 Seventh phase of deformation (D^) 58 2.1.12 Late faults 58 PART 2 Relationship of igneous intrusions to the 62 structural sequence 2.2.1 Introduction 62 2.2.2 (i) Pre-D^ or early syn-D^ intrusions 63 (ii) Syn-D^ trondhjemite dykes 66 2.2.3 Syn-D^ intrusions 67 (i) Gabbros 67 (ii) Diorites 68 (iii) Porphyritic granodiorite 68 (iv) Syn-I^ trondhjemites 69 (v) Syn-T^ multiple dykes 69 2.2.4 (i) Syn-D^ intrusions 70 (ii) Granites 71 (iii) Syn-D^ multiple dykes 72 2.2.5 Post-D^-pre-Dg intrusions 73 2.2.6 Syn-D^ intrusions 74 2.2.7 Basic dykes 75 2.2.8 Summary 76 iv Page No, PART 3 • The relationship of veins and pegmatites 78 to the structural sequence 2.3.1 Introduction 78 2.3.2 - Syn-D^ vein neosomes 80 2.3.3 Syn-D^ vein neosomes 81 2.3.4 Syn-D^ vein neosomes 82 2.3.5 Syn-D^ pegmatites and veins 84 2.3.6 Syn-D,. vein neosomes . 84 2.3.7 Syn-D^ vein neosomes 85 2.3.8 Syn-D^ and post-D^ neosomes 86 PART 4 * Metamorphic history 88 2.4.1 Introduction 88 2.4.2 (i) M^ mineral assemblages 89 (ii) M^ mineral conditions 100 2.4.3 (i) M2 mineral assemblages 103 (ii) M2 metamorphic conditions n o 2.4.4 Metamorphism during 113 2.4.5 Later recrystallisation 114 2.4.6 Summary 115 PART 5 : Summary of the tectono-metamorphic develop- 117 ment and syn-kinematic intrusive history of the Virtasalmi District and the kinematic interpretation and regional correlation SECTION 3 : Amphibolites, skarns and Cu-deposit PART 1 : The geochemistry and origin of the amphib- 122 olites and calc-silicate skarns 3.1.1 Introduction 122 3.1.2 Analytical techniques, methodology (and 123 terminology) 3.1.3 General chemical characteristics 123 3.1.4 Nature of the chemical mobility 130 (i) Pre-D^-M^ alteration 130 (ii) Syn-D^-M^ alteration 140 (iii) Syn-D2~M2 alteration 143 (iv) Post-D2~M2 alteration 144 V Page No. 3.1.5 Origin of the calc-silicate skarns : 145 summary 3.1.6 Chemical subdivisions and petrogenesis 147 of the amphibolites 3.1.7 Petrogenetic and source variability 155 3.1.8 Tectonic setting 162 PART 2 : The origin, nature and structure of the 171 Hallinmaki Cu-deposit 3.2.1 Introduction 171 3.2.2 Distribution of lithologies 172 (i) Major structural features 172 (ii) Minor structural features in the Mine 172 vicinity a) structures 173 b) structures 174 c) structures 174 d) Post-D^ structures 174 (iii) Stratigraphy 175 a) S.O.P. stratigraphy 175 b) T175m stratigraphy 177 c) T370m stratigraphy 179 d) T95m stratigraphy 180 (iv) Major structural and stratigraphic synthesis 181 3.2.3 Timing of mineralisation 183 (i) Introduction 183 (ii) Petrofabric evidence 183 (iii) Relationship to intrusions 184 (iv) Timing of mineralisation : summary 185 3.2.4 Nature and extent of syn-lcinematic ore 186 remobilisation (i) Syn-D^ mobilisation 186 (ii) Syn-D2 mobilisation 188 (iii) Syn-D^ mobilisation 189 (iv) Post-D^ mobilisation 193 3.2.5 Model for formation of Hallinmaki Cu- 193 deposit 3.2.6 Conclusions 199 VI Page No. SECTION 4 Chemistry, petrogenesis and origin of syn-tectonic intrusions 4.1 Introduction 201 4.2 Sampling constraints 201 4.3 Classification 203 4.4 Major and trace element geochemistry 205 4.5 Origin of the syn-kinematic intrusive 208 suite - a summary and discussion (i) Stoping and assimilation 209 (ii) Partial melting 209 (iii) Fractional crystallisation 210 (iv) Discussion 210 SECTION 5 Conclusions 214 References 225 Appendix 1 1. Sample collection and preparation 246 2. XRF rock analysis for major and trace 246 elements 2.1 Method 246 2.2 Results : major elements 247 2.3 Results : trace elements 247 Appendix 2 Tabulated geochemical analyses 250 Appendix 3 289 vii ABSTRACT The Hallinmaki Cu-deposit is a polyphase deformed and metamorphosed orebody located within the Early Proterozoic Svecofennides of South-Central Finland. The lithological assemblage within which the orebody is situated dominantly comprises amphibolites, with minor marbles, calc-silicate skarn lithologies and gneisses, together with syn-kinematic intrusions dominantly of tonalitic composition.

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