Geology and Ore Deposits of the Central African Copperbelt

Home , Carrollite, Copperbelt, Kipushi, Lumwana, Mufulira, Nkana (constituency)

GEOLOGY AND ORE DEPOSITS OF THE CENTRAL AFRICAN COPPERBELT

David W. Broughton A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Geology).

Golden, Colorado

Date ______

Signed: ______David W. Broughton

Signed: ______Dr. Murray Hitzman Thesis Advisor

Golden, Colorado

Date ______

Signed: ______Dr. Paul Santi Professor and Acting Head Department of Geology and Geological Engineering

ABSTRACT

The Central African Copperbelt (CACB) is the world’s largest and highest-grade sedimentary- rock hosted stratiform copper (sedimentary copper) province, and contains a metallogenic endowment and diversity unique amongst such provinces. The CACB extends ~450km from the Zambian Copperbelt

(ZCB) in the southeast through the Congolese Copperbelt (CCB) to the northwest, and also includes deposits in the North West Province of Zambia. It is hosted in Neoproterozoic metasedimentary rocks of the Katangan Supergroup deposited in an evolving intracontinental rift, the Katangan basin. The basal

Roan Group includes early rift-stage continental siliciclastic rocks (redbeds) and overlying mixed evaporitic carbonate and siliciclastic rocks (Lower and Upper Roan subgroups in the ZCB; R.A.T., Mines and Dipeta subgroups in the CCB), followed by marine siliciclastic and mafic igneous rocks (Mwashya

Subgroup). These rocks are overlain by thick diamictite of the Grand Conglomerate Formation of the lower Nguba Group. Subsequent deposition of carbonate rocks and relatively monotonous, non-evaporitic siliciclastic rocks of the Nguba Group and a similar diamictite-carbonate-siliciclastic sequence in the

Kundelungu Group preceded basin inversion during the Pan-African (~590 – 500 Ma) Lufilian orogeny.

Sedimentary copper deposits in the CACB occur in multiple lithologies and stratigraphic positions and vary in type of mineralization and alteration, but share important characteristics. Deposits generally occur within reduced facies rocks above oxidized facies rocks at the lowest redox boundary within the Roan and lower Nguba groups. This boundary is differently positioned throughout the CACB, and may be stratigraphically or structurally controlled. Many deposits are located in the vicinity of macro- structural features, primarily growth faults and large anticlines and synclines formed during Lufilian inversion of such faults. These structures appear to have controlled fluid flow, directly or by influence on sedimentary and diagenetic facies.

Evaporitic strata within the Roan Group influenced the development of the basin and its deposits.

Basin-margin settings such as the ZCB had relatively minor accumulations of halite and contain autochthonous and relatively undeformed, laterally continuous deposits proximal to basement. Non- iii marine evaporites may have been present. The CCB represents a basin-central setting characterized by halokinetic (salt movement) structures and disrupted allochthonous deposits distal from basement, and likely contained significant accumulations of halite.

The evaporitic strata contain distinctive breccias interpreted as marking the former position of evaporites. Breccias in the ZCB form lenticular bodies at the tops of shallowing-upwards evaporitic sequences in the Upper Roan Subgroup. The number of sequences and thickness of evaporitic strata and breccia display a systematic relationship to interpreted growth faults, defining footwall condensed sections and hangingwall depocenters. Observations in the ZCB and near the Kamoa deposit in the western CCB suggest that breccia formation occurred through a combination of dolomite replacement of gypsum, evaporative dissolution and collapse, and texturally destructive dolomite/magnesite-albite alteration. In the CCB, breccia forms ~stratiform and discordant structures (diapirs, intrusions) and

“megabreccia’ enclosing mineralized fragments of rocks of the Mines Subgroup. Many fragments were emplaced upon rocks of the upper Kundelungu Group prior to or during the onset of the Lufilian orogeny.

Evaporitic strata and processes generated residual and dissolution brines capable of mobilizing ore metals. Analysis of fluid inclusion solutes indicates that the majority of deposits studied to date in both the ZCB and CCB formed from metalliferous residual brines generated during deposition of evaporites. Halokinetic and tectonic disruption of such deposits in the CCB post-dated this mineralization event. In contrast, ore sulfides from the post-metamorphic (450Ma) Kipushi deposit and breccia from the basin-central Kolwezi district in the western CCB have a solute signature indicative of partial derivation from halite dissolution, consistent with the association of these areas with halokinetic structures. Breccia from the ZCB has a distinct Na-rich signature suggestive of dissolution of non-marine evaporites.

Potassic and sodic alteration in the ZCB are partitioned within the Lower Roan and Upper Roan-

Mwashya subgroups, respectively. Breccia occurs primarily within the latter. These observations suggest that deposition of halite and/or other sodic evaporites occurred primarily within the Upper Roan

Subgroup.

Dissolution and collapse of evaporitic strata and production of dissolution brine probably commenced with a change to open marine conditions during Mwashya time, and continued during glacial and post-glacial events associated with deposition of the Grand Conglomerate Formation. Halokinetic structures present at higher levels in the CCB suggest that evaporites there were preserved at least locally until the onset of Lufilian inversion.

Thick overlying siltstone-shale, diamictite, and mainly fine-grained siliciclastic deposits of the

Mwashya Subgroup and Nguba and Kundelungu groups formed a hydrological and possibly thermal seal, evidenced by the low abundance of deposits and alteration in these upper portions of the Katangan

Supergroup.

A long history of formation of residual and dissolution brines is consistent with abundant evidence for a protracted history and varied styles and types of mineralization and alteration, at different stratal levels and in different rock types throughout the CACB. The remarkable productivity of this basin and its prospects for discovery of additional deposits are directly linked to this complexity.

TABLE OF CONTENTS ABSTRACT ...... iii

LIST OF FIGURES ...... x

LIST OF TABLES ...... xii

ACKNOWLEDGEMENTS ...... xiv

CHAPTER 1 INTRODUCTION ...... 1

1.1 Scope of this Study ...... 3

1.2 Location and History ...... 4

1.3 Methodology ...... 4

CHAPTER 2 THE CENTRAL AFRICAN COPPERBELT: DIVERSE STRATIGRAPHIC, STRUCTURAL, AND TEMPORAL SETTINGS IN THE WORLD’S LARGEST SEDIMENTARY COPPER DISTRICT ...... 6

2.1 Regional Geological Setting ...... 8

2.2 Zambian Copperbelt ...... 13

2.2.1 Stratigraphy ...... 13

2.2.2 Copper deposits ...... 15

2.2.3 Konkola-Musoshi deposit ...... 18

2.2.4 Mufulira deposit ...... 20

2.2.5 Frontier deposit ...... 22

2.2.6 Lonshi deposit ...... 24

2.3 Congolese Copperbelt ...... 25

2.3.1 Stratigraphy ...... 25

2.3.2 Salt tectonic disruption of the Mines Subgroup ...... 29

2.3.3 Copper-cobalt deposits ...... 31

2.3.4 Kolwezi District ...... 34

2.3.5 Tenke-Fungurume district ...... 36

2.3.6 Kinsevere ...... 37

2.3.7 Kamoa ...... 38

2.3.8 Kipushi ...... 38

2.4 North West Province, Zambia ...... 39

2.4.1 Copper deposits ...... 41

2.4.2 Lumwana ...... 41

2.4.3 Sentinel (Kalumbila) ...... 42

2.4.4 Kansanshi ...... 43

2.5 Common Features Of Deposits In The Central African Copperbelt ...... 45

2.6 Timing of Mineralization ...... 49

2.7 Exploration Considerations ...... 52

CHAPTER 3 DISCOVERY OF THE KAMOA COPPER DEPOSIT, CENTRAL AFRICAN COPPERBELT, D.R.C...... 54

3.2 Regional Geology ...... 55

3.3 Exploration Rationale ...... 60

3.4 Discovery of the Kamoa deposit ...... 61

3.5 Litho-Stratigraphy ...... 64

3.5.1 Kibaran Basement Rocks ...... 64

3.5.2 Roan Group Conglomerate and Grit (“Poudingue”) ...... 64 vii

3.5.3 Mwashya Subgroup Feldspathic Sandstone ...... 64

3.5.4 Nguba Group diamictite (“Grand Conglomerate”) ...... 65

3.5.5 Nguba Group pyritic siltstone-sandstone ...... 66

3.5.6 Mafic Rocks ...... 67

3.6 Structure ...... 67

3.7 Mineralization ...... 69

3.8 Significance for SSC Exploration and Genesis ...... 72

CHAPTER 4 BRECCIAS ALONG THE MARGINS OF THE KATANGAN BASIN IN THE CENTRAL AFRICAN COPPERBELT ...... 74

4.2 Regional Geological Setting ...... 76

4.2 Breccia Types ...... 78

4.2.1 Crackle/vein breccia ...... 82

4.2.2 Monolithic clast breccia ...... 82

4.2.3 In situ autolithic breccia ...... 83

4.2.4 Polylithic clast breccia ...... 83

4.2.5 Mafic-associated breccia ...... 87

4.2.6 Angular collapse breccia ...... 88

4.3 Breccias in relation to evaporitic depositional cycles ...... 88

4.4 Stratigraphic position of breccias and lateral variations in breccia types ...... 90

4.4.1 Northern portion of the Zambian Copperbelt - Konkola area ...... 91

4.4.2 Eastern portion of the Zambian Copperbelt ...... 99

4.4.3 Eastern portion of the Zambian Copperbelt - Luansobe area ...... 101 viii

4.4.4 Eastern portion of the Zambian Copperbelt - Mufulira area ...... 103

4.4.5 Eastern portion of the Zambian Copperbelt - Itawa area ...... 106

4.4.6 Southwest portion of the Zambian Copperbelt - Chambishi basin area ...... 111

4.4.7 Kamoa deposit, western margin of the DRC Copperbelt ...... 115

4.5 Geochemical studies ...... 121

4.6 Discussion ...... 124

4.7 Conclusions ...... 129

CHAPTER 5 GEOLOGY AND COBALT-COPPER DEPOSITS OF THE TILWEZEMBE ANTICLINE ...... 132

5.1 Regional Geology ...... 133

5.2 Local Geology ...... 134

5.3 Discussion ...... 137

CHAPTER 6 CONCLUSIONS ...... 139

REFERENCES CITED ...... 145

APPENDIX A CENTRAL AFRICAN COPPER DEPOSITS ...... 159

APPENDIX B DRILL HOLE COLLAR LOCATIONS ...... 167

APPENDIX C CARBON AND OXYGEN ISOTOPES ...... 168

APPENDIX D CRUSH-LEACH ANALYSIS ...... 173

LIST OF FIGURES Figure 1.1: Simplified geological map of the Central African Copperbelt, showing location of selected deposits examined in this study ...... 2

Figure 2.1: Map of southern Africa showing the location of Neoproterozoic basins ...... 7

Figure 2.2: Lithostratigraphy of the Katangan succession ...... 8

Figure 2.3: Highly generalized stratigraphic correlation between Congolese, Zambian, and North West Province areas showing the stratigraphic location of selected copper deposits...... 11

Figure 2.4: Generalized geological map of the Zambian Copperbelt ...... 14

Figure 2.5: Simplified geological map of the Konkola-Musoshi deposit area ...... 19

Figure 2.6: Cross section through the Mufulira deposit ...... 21

Figure 2.7: Frontier deposit. (a) Simplified geological map of the Frontier deposit area. (b) Simplifed cross-section through the Frontier deposit ...... 23

Figure 2.8: Map of the Congolese Copperbelt ...... 26

Figure 2.9: Model for the formation of diapiric breccias and megabreccias in the Central African Copperbelt ...... 30

Figure 2.10: Generalized geological cross section through the Kolwezi district ...... 35

Figure 2.11: Generalized geological map of the North West Province of Zambia (Domes region) showing the locations of the major deposits ...... 40

Figure 2.12: (a) Geological map of the Kansanshi area. (b) Generalized cross section through the Main Pit of the Kansanshi deposit ...... 44

Figure 3.1: Geology of the Kamoa area, showing location of resource ...... 55

Figure 3.2: Simplified stratigraphy of the Congolese Copperbelt ...... 57

Figure 3.3: Contoured copper-in-soil anomalies and second vertical derivative magnetic survey, Kamoa area ...... 62

Figure 3.4: Diamond drill section 8811900N throgh Kamoa deposit ...... 63

Figure 3.5: Contact between green-gray reduced basal diamictite of the Grand Conglomerate (upper core box) and underlying pinkish to maroon Mwashya Subgroup sandstone ...... 65

Figure 3.6: Pyritic siltstone-sandstone of the Kamoa pyritic siltstone (KPS) ...... 66

Figure 3.7: Chalocopyrite textures, Kamoa deposit ...... 69

Figure 3.8: Bornite textures, Kamoa deposit ...... 70

Figure 3.9: Sulfide replacement textures, Kamoa deposit ...... 70

Figure 3.10: Grade distribution, metal and sulfide zoning in hypogene mineralization, Kamoa deposit ... 71

Figure 4.1: Simplified geological map of the Central African Copperbelt ...... 75

Figure 4.2: Stratigraphic column for the Zambian and Congolese Copperbelts...... 76

Figure 4.3: Reproduced historical “type“ examples of breccia from the Congolese Copperbelt ...... 79

Figure 4.4: Breccia types and textures ...... 80

Figure 4.5: Photomicrographs of polylithic clast breccia...... 85

Figure 4.6: Shallowing-upwards evaporitic cycles in the Zambian Copperbelt ...... 89

Figure 4.7: Generalized geology of the Konkola area ...... 91

Figure 4.8: South – north drill section for the Upper Roan Subgroup across three major structural blocks in the Konkola mine area ...... 93

Figure 4.9: Evaporitic and incipient breccia textures in Upper Roan Subgroup, Konkola area ...... 94

Figure 4.10: Geological log of drill hole L83, Luansobe prospect ...... 100

Figure 4.11: Northwest-southeast strike section at Luansobe prospect ...... 102

Figure 4.12: Simplified geology of the Mufulira area projected to surface ...... 103

Figure 4.13: Strike section through deep drill holes at Mufulira deposit ...... 104

Figure 4.14: Geological map and drill plan, Itawa prospect...... 106

Figure 4.15: South-north drill section of geological logs of drill holes through Itawa prospect ...... 108

Figure 4.17: Composite photograph of drill core from the brecciated portion of drill hole IT26 ...... 109

Figure 4.18: Breccia sequence in drill hole IT26 ...... 110

Figure 4.19: Chambishi basin area. (a) Simplified geological map. (b) Simplified log of middle portion of drill hole RCB2 ...... 112

Figure 4.20: Simplified geological map of Kamoa area ...... 116

Figure 4.21: Breccia and evaporite in Roan Group in hole DMAK_DD009, south of Kamoa area ...... 118

Figure 4.22: Carbon and oxygen isotopic data for carbonates in ZCB, this study...... 121

Figure 4.23: Molar ratios of Cl/Br versus Na/Br of fluid inclusion solutes from the Zambian Copperbelt ...... 123

Figure 5.1: Simplified geological map of the Congolese Copperbelt ...... 132

Figure 5.2: Geological map of the Tilwezembe anticline area ...... 134

Figure 6.1: Simplified geological map of the Central African Copperbelt, showing the distinction between basin-marginal, autochthonous deposits and basin-central, allochthonous deposits ...... 140

Figure 6.2: Schematic representation of timing of sedimentation, production and mobilization of evaporite and brine, major basin events, and mineralization in the CACB...... 143

xii

LIST OF TABLES Table 5-1: Estimated copper-cobalt resources of deposits in the Tilwezembe anticline...... 135 Table A-1: Central African Copperbelt Deposits...... 159 Table C-1: Exploration drill hole collar locations...... 167 Table D-1: Carbon and oxygen isotope results...... 168 Table E-1: Crush-leach analysis results...... 174

xiii

ACKNOWLEDGEMENTS

I would like to begin by expressing my gratitude to my advisor, co-researcher, and mentor Dr.

Murray Hitzman, who convinced me to undertake this project, worked with me through the many years since then, and sent key emails that gave me the time to finish. Murray, it was a great pleasure and privilege to have shared so many hours and ideas with you. It has been quite a journey from Kansanshi to

Tenke to Kamoa and you have shown more enthusiasm, insight and patience than anyone could expect.

My other committee members also contributed significantly during my time at CSM. Dr. John

Warme re-introduced me to stratigraphy, Dr. John Humphrey to carbonate sedimentology and isotopes, and Dr. Rod Eggert to natural resource economics. Thanks finally to Dr. Hugh Miller for being committee head. Debbie Cockburn and Marilyn Schwinger were not committee members, but must have felt so!

The sponsors and co-researchers of AMIRA P544 and P872 are thanked for their support, financial and logistical assistance, and access to company drill cores and properties. Special thanks go to co-researchers David Selley, Stuart Bull, Rob Scott, and Mawson Croaker. Discussions with industry geologists were many, but I would single out Alan Stephens, Jon Woodhead, Claus Schlegel, James

Mwale, Hugh Carruthers, Doug Jack, and Mike Christie. Funding also came from the SEG Hugh

McKinstry grant program, for which I am thankful. Work with Poul Emsbo at the USGS on crush-leach studies fundamentally changed the way we thought about brines.

While at Phelps Dodge, Rich Leveille and Will Wilkinson initiated a global field review of stratiform copper deposits, which contributed significantly to understanding these deposits. They don’t always stick out of the ground! Discussions with Wolf Schuh and Alfred Bogaers were always fruitful.

With Ivanplats/Ivanhoe I have been fortunate to explore a unique land package in DRC, and to be involved with a remarkable discovery. Thanks to all the colleagues at Kamoa and Regional Exploration:

Tom Rogers, David Edwards, Steffen Kalbskopf, Duncan Proctor, Tim MacIntyre, Mike Kirschbaum, and Danielle Schmandt deserve particular mention. My appreciation also is extended to Robert Friedland,

Lars-Eric Johansson, and Mike Gray for the time to finish this thesis, and to Nicholas Kerr for formatting.

xiv

Over the years many others have supported and collaborated, more than can be mentioned. Some sadly have passed: Eric Nelson, Oliver Warin and Rod Kirkham are warmly remembered. To Maeve

Boland, special thanks for the encouragement and for letting Murray and I do our thing! To my office- mate at CSM, Efem Altinok, now I know why you read Nietzsche! Finally, my family has seen me through all the ups and downs and made so many more sacrifices than I have. To Sandy, Claire, Gerry and James, Mum and Dad, heartfelt thanks, this is for you.

“Once in a while you get shown the light, in the strangest of places if you look at it right” (Robert Hunter).

Oliver, you were right!

CHAPTER 1

INTRODUCTION

Sedimentary rock-hosted stratiform copper (sedimentary copper) deposits are important sources of Cu, Co, and Ag, accounting for ~15% of the world's Cu resource (Sillitoe, 2012). The Central African

Copperbelt (CACB) is the world’s largest and highest-grade sedimentary copper province (Appendix A;

Cox et al., 2007; Lydall and Auchterlonie, 2011; Hitzman et al., 2012), with more than 200 Mt of copper produced or in reserves and with the world’s largest reserves of cobalt. The CACB also contains significant deposits of zinc, uranium, and nickel (Unrug, 1988; Hitzman et al., 2012; Capistrant, 2013).

The heart of the province extends along a >450-km-long arcuate trend north and westward from the

Zambian Copperbelt (ZCB: Mendelsohn, 1961a; Fleischer et al., 1976; Selley et al., 2005) into the

Congolese Copperbelt (CCB: Demesmaeker et al., 1963; Oosterbosch, 1962; François, 1973, 1974, 2006;

Cailteux, 1994) in the Democratic Republic of Congo (DRC) (Figure 1.1). Recent discoveries and project developments in Zambia’s North West Province (Figure 1.1; Hitzman et al., 2012; Capistrant, 2013) and the CCB (Broughton and Rogers, 2010; this work) demonstrate the continued prospectivity of the province.

The CACB is hosted by Neoproterozoic metasedimentary rocks of the Katangan Supergroup

(<880 to ~550Ma), which were deposited following initiation of an intracontinental rift basin (Katangan basin) (Annels, 1984; Unrug, 1988; Kampunzu et al., 2000; Selley et al., 2005) and deformed during the

Lufilian orogeny (~590 to ~500Ma; Rainaud et al., 2005; Selley et al., 2005 and references therein). As with most sedimentary copper provinces (Kirkham, 1989; Brown, 1997, 2003; Hitzman et al., 2005), evaporites are thought to have provided salinity to ore-forming oxidized basinal brines and sedimentary copper deposits occur in reduced- or formerly reduced-facies rocks, generally above hematite-stable siliciclastic rocks (redbeds). Evaporites also are thought to have influenced the tectonic development of the CCB (e.g. salt tectonics: De Magnée and François, 1988; Jackson et al., 2003). Deposits throughout the CACB are restricted to the lower portion of the Katangan Supergroup, in a wide range of host 1

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Figure 1.1: Simplified geological map of the Central African Copperbelt, showing location of selected deposits examined in this study. A distinction is made between basin-marginal, autochthonous deposits located proximal to basement and basin-central, allochthonous deposits located distal from basement.

lithologies at different stratigraphic positions and with a variety of textural styles and associated alteration types (Selley et al., 2005; Hitzman et al., 2005, 2012). This metallogenic diversity has been linked to multiple mineralization events spanning the evolution of the Katangan basin, but our understanding of this complexity and of regional-scale controls and processes remains incomplete.

1.1 Scope of this study

This study takes a regional-scale, “systems” approach to observation and analysis of the CACB and its diversity. The intent is to view ore deposits within their stratigraphic, structural, basinal, and temporal contexts. The CACB is divided into two general settings: basin-marginal areas with autochthonous ore deposits proximal to basement rocks (the ZCB, Kamoa area, Northwest Province,

Zambia) and a basin-central area (the CCB) where deposits are allochthonous and basement rocks are unknown (Figure 1.1). Links between these different settings and the style and history of their deposits are considered in the context of the role of evaporites in influencing basin and metallogenic evolution.

The location of deposits also is considered in the context of the position of reduced rocks and redox boundaries within the overall stratigraphic sequence and its basinal setting.

This thesis consists of four papers (Chapters 2 to 5) addressing various aspects of the CACB, as well as this introductory chapter and conclusions in Chapter 6. The first two papers have been published and the second two are being readied for submission for publication. Permissions from publisher and co- authors for inclusion of these papers are in Appendix B. Chapter 2 presents an overview of the geology and ore deposits of the province, highlighting the diversity of settings and styles for sedimentary copper deposits. Chapter 3 describes the geology and discovery history of the giant Kamoa deposit, which occurs in a basin-margin setting at the western edge of the CCB and illustrates the significance of stratigraphically controlled changes in the position of redox boundaries in localizing mineralization.

Chapter 4 examines the geology, stratigraphic setting, and origin of enigmatic breccia bodies in the basin- margin ZCB and Kamoa areas. Similar breccia occurs throughout the CACB, and these breccias play a fundamental but poorly understood role in the evolution of the Katangan basin and the CACB. Chapter 5 describes the geology of the Tilwezembe anticline in the western part of the CCB. This anticline hosts five newly discovered and/or developed, unusually cobalt-rich copper deposits and also displays a structural style compatible with salt tectonics.

1.2 Location and history

The CACB is located in Sub-Saharan Africa in the DRC and Zambia (Figure 1.1). It has produced copper for more than 4000 years (Broughton et al., 2002) and in the 1960s and 70s was a leading global copper producer. A recent resurgence in exploration and mining activity in the province subsequent to privatization of the industry in 1995 and 2003 in Zambia and DRC, respectively has led to its once again becoming a world leader in metal production (e.g. Lydall and Auchterlonie, 2011).

The CACB is located at elevations of 1100 to 1600 m, resulting in a reasonably moderate climate for its latitude (~10 to 12 degrees south). Nevertheless, high seasonal rainfall and temperatures have produced a deeply weathered surficial environment with only sparse outcrop. Exploration therefore has relied on soil geochemistry, magnetic, electrical, and electromagnetic geophysical surveys, and diamond drilling. Seismic datasets are not available. Government- and industry-sponsored drill core archives are a critical resource for exploration geologists and researchers and were utilized extensively in this study.

1.3 Methodology

This study has spanned approximately 14 years of field-, university-, and corporate-based research activities. The initial period from mid-1999 through late 2003 formed part of an industry- sponsored research project, AMIRA P544, where the author’s primary focus was logging of deep stratigraphic drill holes throughout the ZCB. Approximately 25,000 m of drill core was examined and/or logged from all of the major deposits in the ZCB (Appendix C), focusing primarily on rocks below and above the orebodies. These stratigraphic cores were critical in facilitating a systems approach for the study. Geological mapping was completed at open pit exposures. Transmitted and reflected light petrography on 136 samples from these cores, augmented on selected samples by cathodoluminesence studies, was performed at the Colorado School of Mines. Thin sections from the existing school collection were also examined. Two hundred and fifty selectively drilled carbonate samples were analyzed at the

Colorado School of Mines Stable isotope Laboratory to measure δ18O and δ13C isotope values (Appendix

D). Results of the AMIRA P544 project were published in the 100th Anniversary Volume of the Society of Economic Geologists (Selley et al., 2005) with the writer as second author.

The second phase of the study comprised participation in the AMIRA P872 project focused on geological studies in the CCB. Research again included logging and petrography of exploration drill holes, primarily at the Tenke-Fungurume deposit, presented as part of the P872 final report (Selley et al.,

2010). This work is not included in detail here but an overview is provided in Chapter 2. During this period, the compositions of fluid inclusion solutes from selected samples of ore sulfides, secondary dolomite, and dolomite matrix of polylithic breccia were analysed by a bulk crush-leach method by Dr.

Poul Emsbo at the U.S.G.S. labororatory in Denver, CO (Appendix E).

Since rejoining industry in 2007 the writer has focused on exploration in the CCB, including discovery and delineation of the Kamoa copper deposit. Drill core-based and regional studies of stratigraphy, alteration and mineralization resulting from this work are presented in Chapters 3 and 5.

CHAPTER 2

THE CENTRAL AFRICAN COPPERBELT: DIVERSE STRATIGRAPHIC, STRUCTURAL,

AND TEMPORAL SETTINGS IN THE WORLD’S LARGEST SEDIMENTARY COPPER

DISTRICT

Sedimentary rock-hosted stratiform copper or sedimentary copper deposits are important sources of Cu, Co, and Ag (Gustafson and Williams, 1981; Boyle et al., 1989; Hitzman et al., 2005), accounting for ~15% of the world's Cu resource (Sillitoe, 2012). The Central African Copperbelt is the world’s largest and highest-grade sedimentary copper province with close to 200 Mt of copper produced or in reserves and the world’s largest reserves of cobalt (Appendix A; Cox et al., 2007; Lydall and

Auchterlonie, 2011). The heart of the province extends along a 400-km-long arcuate trend north and westward from the Zambian Copperbelt (Mendelsohn, 1961a; Fleischer et al., 1976; Selley et al., 2005) into the Congolese Copperbelt (Demesmaeker et al., 1963; Oosterbosch, 1962; François, 1973, 1974,

2006; Cailteux, 1994) in the Democratic Republic of Congo (DRC) (Figure 2.1). This paper is intended to provide a geological overview of this world-class district and capture both the similarities and diversity between its numerous individual deposits.

The Zambian Copperbelt, with combined production and reserves/resources totaling approximately 100 Mt Cu (Hitzman et al., 2005), contains six large deposits (Konkola-Musoshi,

Nchanga-Chingola, Nkana-Mindola, Mufulira, Luanshya-Baluba, and Chambishi) and almost 20 smaller deposits, not all of which have been mined. Mines in the Zambian Copperbelt include large open pits and a number of underground operations. The Congolese Copperbelt, with combined production and reserves totaling over 180 Mt Cu, contains three large deposits (Kamoa, Kolwezi, and Tenke-Fungurume) and a number of smaller deposits. With the exception of the Kolwezi district, most mines in the Congolese

Copperbelt have been open pit operations. Three large deposits (Kansanshi, Lumwana, and Sentinel), with combined production and reserves/resources of ~19 Mt of Cu, occur in Zambia’s North West

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Figure 2.1: Map of southern Africa showing the location of Neoproterozoic basins including the main Katangan basin in the southern Democratic Republic of Congo (DRC) hosting the Congolese Copperbelt, the much smaller series of basins hosting the Zambian Copperbelt, and the North West Province of Zambia.

Province; all are open pit mines. The Central African Copperbelt also contains significant deposits of zinc, nickel, and uranium. Although there are important differences between the various deposits and districts within this metallogenic province, all are products of an evolving basinal system and all can be related to processes observed in other sedimentary copper districts (Hitzman et al., 2005).

2.1 Regional geological setting

The deposits of the Central African Copperbelt are hosted in rocks of the Neoproterozoic

Katangan Supergroup, which has a maximum estimated thickness of 5-10 km (Batumike et al., 2007; Bull et al., 2011). These rocks were deposited within a series of linked intracratonic extensional basins or depocenters associated with the breakup of Rhodinia (Unrug, 1988; Kampunzu et al., 1993, 2000; Porada and Berhorst, 2000). They are subdivided into three main sequences (Figure 2.2): the basal Roan Group which includes initial rift-stage siliciclastic rocks, post-rift evaporitic carbonate rocks, and second rifting- stage siliciclastic rocks and mafic igneous flows and sills; the Nguba Group which includes at its base a regional marker, the glaciogenic Grand Conglomérat; and the Kundelungu Group which also commences with a glaciogenic unit, the Petit Conglomérat (Selley et al., 2005). These rocks were variably metamorphosed and deformed during the ~590 – 500 Ma Pan-African Lufilian orogeny, but in most areas outside of the North West Province of Zambia retain their sedimentary structure, hence a “meta” prefix is not used in most descriptions of the rocks.

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Figure 2.2: Lithostratigraphy of the Katangan succession in the Congolese, Zambian, and North West Province areas, based primarily on Cailteux et al. (2005a) and Selley et al. (2005).

While sharing broadly similar stratigraphic sequences, individual depocenters had distinctive features, particularly within the basal successions. The economically most important and hence best-studied depocenters are those in the Zambian Copperbelt and the Congolese Copperbelt (Figure 2.1). The

Zambian Copperbelt formed within a relatively narrow series of basins and horsts and contained one major evaporitic sequence within the Roan Group above the level of ore. The main Katangan depocenter hosts the Congolese Copperbelt and contained at least three evaporite sequences within the Roan Group, including one below the level of ore (De Magnée and François, 1988; Jackson et al., 2003). The geologically less well-known North West Province contains siliciclastic, carbonate, and evaporitic rocks broadly correlative with the Roan Group.

The maximum age of the basal Roan Group strata is constrained in Zambia by the unconformably underlying 883±10 Ma Nchanga granite (Armstrong et al., 2005). The lower and middle Roan Group in the Zambian Copperbelt has traditionally been subdivided into a syn-rift, predominantly subaerial to shallow marine siliciclastic Lower Roan Subgroup containing most of the ore deposits, and a post-rift, predominantly marine Upper Roan Subgroup containing platformal carbonate rocks, stratiform to discordant breccias probably after evaporites, and subordinate siliciclastic rocks (Figure 2.2) (Selley et al.,

2005; Bull et al., 2011). The Copperbelt Orebody Member (“Ore Shale”) of the Lower Roan Group represents the culmination of early rift-stage extension and the first marine incursion within the Katangan basin in the Zambian Copperbelt.

The lower and middle Roan Group in the Congolese Copperbelt (Figure 2.2) comprises a basal unit of variably dolomitic fine-grained siliciclastic rocks, the R.A.T. (Roches Argilo-Talqueuses)

Subgroup, overlain by dolomites and mixed dolomite-siliciclastic rocks of the Mines and Dipeta subgroups of probable marine origin (François, 1973; Cailteux, 1994; Cailteux et al., 2005a; Kampunzu et al., 2005). However, these rocks are present only as blocks or “écailles” (in French, fish scales) within megabreccias that are interpreted to result from halokinetic movement within the Roan Group sequence 9

(Demesmaeker et al., 1963; De Magnée and François, 1988; Kampunzu and Cailteux, 1999; Jackson et al., 2003).

The stratigraphic correlation between lower and middle Roan Group sedimentary rocks in the

Zambian and Congolese Copperbelts has been contentious and hampered by the lack of exposure of the base of the Roan Group sequence in the DRC. Many workers, most recently Cailteux et al. (2005a, 2007), have linked the Copperbelt Orebody Member of the Lower Roan Subgroup in Zambia with the ore- bearing Kamoto Formation of the Mines Subgroup in DRC. However, the Kamoto Formation may also be correlated with the more carbonate-dominant Upper Roan Subgroup (Gray, 1930). In the hangingwall to the Mufulira deposit in Zambia, mineralized carbonate rocks of the Upper Roan Group have been correlated with rocks of the Kamoto Formation (Cailteux et al., 1994) above a sequence of breccias that are variably interpreted as representing major décollements (Cailteux et al., 1994; Cailteux and

Kampunzu, 1995), sedimentary syn-orogenic conglomerates (Wendorff, 2005a), or stratiform, salt-related breccias (Selley et al., 2005). The lack of lithostratigraphic repetition associated with these breccias in the

Zambian Copperbelt (Mendelsohn, 1961a) discounts a primarily structural origin. Sequence stratigraphic analysis of the Zambian Copperbelt recognizes seven sequences within the Roan Group (Bull et al.,

2011), which when compared with the DRC stratigraphy supports Gray’s 1930 interpretation. This interpretation, if correct, would imply that the equivalent of the Copperbelt Orebody Member lies below the R.A.T. Subgroup in the DRC; this is the correlation adopted in this paper (Figure 2.3).

In the Zambian Copperbelt, evaporitic textures locally occur within and directly above the

Copperbelt Orebody Member, but become prominent within the Upper Roan Subgroup (Annels, 1974;

Selley et al., 2005; Bull et al., 2011). The Copperbelt Orebody Member is undisrupted throughout the district, implying that the Zambian orebodies are fundamentally below a major evaporitic sequence. In contrast, the DRC orebodies of the Kamoto Formation are ubiquitously disrupted by breccias interpreted to be derived at least in part from former evaporites in or below the R.A.T. Subgroup (François, 1974;

Cailteux and Kampuzu, 1995; Jackson et al., 2003) and are therefore supra-salt. In summary, there appear

10 to be two major mineralized levels in the Roan Group rocks: one below, or laterally equivalent to, a former evaporite (Copperbelt Orebody Member, Zambia), and one above it (Kamoto Formation, DRC).

! ! # # # " ) " *+ '

%'()

" ) # $ % # & ' ( !

$ % &

" ' ' + '

*+ , Figure 2.3: Highly generalized stratigraphic correlation between Congolese, Zambian, and North West Province areas showing the stratigraphic location of selected copper deposits. Deposits occur from the basement up into the basal Nguba Group.

In both Zambia and the DRC, the Mwashya Subgroup at the top of the Roan Group overlies the uppermost level of breccia and traditionally was viewed as being composed of a lower dolomitic sequence and an upper, normally shale-dominated siliciclastic sequence (Mendelsohn, 1961a; François

1973; Cailteux, 1994). More recent work in both Zambia and Katanga places the lower dolomitic sequence within the Upper Roan/Dipeta Subgroup and recognizes significant lateral facies changes within the upper siliciclastic sequence (Cailteux et al., 2007; Bull et al., 2011).

The overlying Nguba and Kundelungu groups (Figure 2.2) are dominated by siliciclastic sedimentary rocks with lesser carbonate rocks. Both successions have basal diamictites termed the Grand and Petite Conglomérat, respectively (François, 1973). The Grand Conglomérat is composed of variably clast-rich diamictites with mudstone/siltstone/sandstone interbeds and has traditionally been interpreted as a Sturtian–age (735-765 Ma), glacially derived sequence (Binda and Van Eden, 1972; Wendorff and Key,

2009; Master and Wendorff, 2011). The basal unit of the Kundelungu Group is the Petite Conglomérat, a diamictite that is believed to be time-equivalent to the 635 Ma Marinoan (Hoffmann et al., 2004; Master and Wendorff, 2011) glaciogenic event. This diamictite is overlain by weakly metamorphosed and deformed limestones and dolomitic sandstones, siltstones and argillites. The uppermost Kundelungu

Group comprises undeformed, flat-lying argillaceous sandstones, arkosic sandstones, and conglomerates of the Plateaux Subgroup (Cailteux et al., 2005a; Batumike et al., 2006, 2007).

Mafic igneous activity occurred in the Central African Copperbelt between 735-765 Ma,

synchronous with the deposition of the Mwashya Subgroup and the basal Nguba Group (Kampunzu et

al., 1993, 2000). Gabbro sills have been dated at 742-753 Ma in northwest Zambia (Barron, 2003).

Mafic flows within Mwashya Subgroup rocks in northwest Zambia were erupted at ~765 Ma (Key et al.,

2001) and form part of a regional suite of mafic rocks along the western margin of the Katangan basin.

In contrast, the Congolese Copperbelt contains relatively few known mafic rocks. Halokinesis of Roan

Group evaporites deposited in the main Katangan basin was probably initiated during Mwashya-lower

Nguba time and influenced depositional thickness of the Nguba Group (D. Selley, unpub. data, 2005).

Pan-African inversion and deformation of the Katangan succession occurred during the ~590 –

500 Ma Lufilian orogeny and produced an arcuate belt of open to tight folds and reverse faults extending from the Kolwezi area of DRC to the Zambian Copperbelt (Cahen et al., 1984; Kampunzu and Cailteux,

1999; Rainaud et al., 2005). In the Zambian Copperbelt, the Lufilian event resulted in basin inversion with reverse movement and complex folding along and adjacent to earlier formed normal faults

(McGowan et al., 2003, 2006; Selley et al., 2005). Metamorphism and deformation associated with the

Lufilian event are regionally heterogeneous. Katangan rocks of the Congolese Copperbelt generally 12 reached chlorite (lower greenschist) facies whereas rocks in the Zambian Copperbelt contain biotite/phlogopite and attained greenschist to lower amphibolite facies (Ramsay and Ridgeway, 1977).

Rocks in the North West Province of Zambia (often termed the Domes area) commonly contain garnet- and/or kyanite-bearing assemblages (Cosi et al., 1992; Broughton et al., 2002); peak metamorphic conditions have been defined by talc-kyanite whiteschists located along the contact between the basement and the Katangan Supergroup sedimentary sequence dated at ~530 Ma (John et al., 2004). The heterogeneity of Lufilian metamorphism has traditionally been ascribed to crustal exhumation and thrust stacking of basement and Katangan rocks linked to closure of a southern ocean basin (Cosi et al., 1992;

Coward and Daly, 1984; Porada and Berhorst, 1998, 2000; John et al., 2004).

2.2 Zambian Copperbelt

The Zambian Copperbelt (Figure 2.1 and Figure 2.4) contains a number of large deposits

(Konkola-Musoshi, Nchanga-Chingola, Nkana-Mindola, Mufilira, Luanshya-Baluba, and Chambishi) and several deposits that are actually located just inside the DRC (Musoshi, Frontier, Lonshi). The Zambian

Copperbelt has been the subject of a large number of publications on individual orebodies and the district as a whole, notably Mendelsohn (1961a), Fleischer et al. (1976), and Selley et al. (2005). Given the rich literature and the relatively recent summary paper by Selley et al. (2005), we will primarily present highlights that aid in comparison of this district to the Congolese Copperbelt and the deposits in the North

West Province of Zambia as well as new data on the Frontier and Lonshi deposits which have not been previously described in the literature.

2.2.1 Stratigraphy

Deposits in the Zambian Copperbelt are hosted primarily in the Lower Roan Subgroup (Figure

2.2 and Figure 2.3). The lowermost Mindola Clastics Formation contains laterally discontinuous continental sandstones and conglomerates. These are abruptly overlain in the western Zambian

Copperbelt by a regionally extensive, variably organic-rich marginal marine siltstone/shale termed the deposits. In the eastern portion of the Zambian Copperbelt the Kitwe Formation is dominated by

&'( %3 $ &* && &) &- &+ ,$ 3 $ , )1 ! 3 $ &. " # % # &/ *- )' )0 &0 )/ $ $ )) )+ ). )& 1 &' && )- )* 2 $

' &1 / 0

. *+ *)

)*( % ! *& * & - ) **

&+,$

Figure 2.4: Generalized geological map of the Zambian Copperbelt. The map is modified from Darnley

(1960), Mendelsohn (1961a), Annels (1984), Fleischer (1984), Sweeney and Binda (1989), and Selley et al. (2005) with additional data from First Quantum Minerals, Ltd. Zambia for the eastern edge of the district. Deposits: 1 = Luanshya, 2 = Roan Extension, 3= Baluba, 4 = Lufubu South, 5 = Chibuluma South, 6 = Chibuluma West, 7 = Chibuluma, 8 = Nkana-Mindola, 9 = ChambishiSouth East, 10 = Chambishi, 11 = Pitanda, 12 = Mwambashi A, 13 = Mwambashi B, 14 = Samba, 15 = Fitula, 16 =Mimbula, 17 = Chingola A-F, 18 = Nchanga, 19 = Fitwaola, 20 = Konkola, 21 = Konkola Deep, 22 – Konkola North, 23 = Musoshi, 24 = Lubembe, 25 = Luansobe, 26 = Kasaria, 27 = Mufulira, 28 = Frontier (Lufua), 29 = Mwekera, 30 = Ndola West, 31 = Itawa, 32= Bwana Mkubwa, 33 = Lonshi, 34 = Mokambo.

siliciclastic sedimentary rocks. Throughout the Zambian Copperbelt the Kitwe Formation passes upwards into laterally extensive shallow marine carbonates and generally finer grained siliciclastic rocks with

14 abundant evaporite textures and mainly stratabound breccias, termed the Upper Roan Subgroup. The overlying Mwashya Subgroup comprises mainly deeper water carbonaceous shales, siltstones, and clastic carbonate rocks (Cailteux et al., 2007; Bull et al., 2011). The Grand Conglomérat at the base of the overlying Nguba Group is relatively thin and commonly carbonaceous (Binda and Van Eden, 1972). The

Nguba and Kundelungu groups are poorly known in the Zambian Copperbelt.

Three significant tectonic events affected the Zambian Copperbelt. Extension associated with early rifting (post-880 Ma) formed isolated fault-controlled basins, which linked along master faults during deposition of the Copperbelt Orebody Formation (Selley et al., 2005). A second period of extension occurred from deposition of the upper portion of the Mwashya Subgroup to deposition of the lower Nguba Group (~765–735 Ma); this rifting event was associated with mafic magmatism. Basin inversion and later compressive deformation (~590–500 Ma) culminated in greenschist-grade metamorphism (~530 Ma) during the Lufilian event.

2.2.2 Copper deposits

The majority of copper ore deposits in the Zambian Copperbelt occur within a 200 meter stratigraphic interval centered on the Copperbelt Orebody Member. Deposits in the Copperbelt Orebody

Member are broadly stratiform and are grouped into argillite- (~70% of ore) and arenite-hosted (~30%) types (Figure 2.4). The distribution, geometry, and size of these deposits are fundamentally controlled by early sub-basin fault architecture and the availability of in situ and mobile reductants, which are also linked to basin architecture (Selley et al., 2005). Argillite-hosted deposits occur within relatively dark and locally carbonaceous dolomitic siltstones and shales and have strike lengths up to 17 km. Highly carbonaceous shales tend to be low grade or barren but may contain economic amounts of copper sulfides where veining is prominent; mineral deposits are concentrated in mildly carbonaceous, dolomitic siltstones. Arenite-hosted deposits occur in both the footwall and hangingwall of the Ore Shale unit and have maximum strike lengths of 5 km. They occur at sites that were geometrically favorable for mobile hydrocarbon or sour gas (natural gas containing significant hydrogen sulfide) accumulation. Both deposit 15 types contain so-called barren gaps of weakly to unmineralized strata, typically associated with the fault- bounded shoulders of early sub-basins (so-called basement highs) (Selley et al., 2005).

While the majority of ore in the Zambian Copperbelt occurs within the Copperbelt Orebody

Member, deposits are known from within the basement (Samba) upwards into the basal Nguba Group

(Frontier, Lonshi, Fishtie [Kashime]) (Figure 2.3). The Zambian Copperbelt contains numerous copper occurrences in the basement (Mendelsohn, 1961a). The largest is the Samba deposit, hosted in 1.9 Ga

(Rainaud et al., 2005) basement metavolcanic rocks on the western edge of the Zambian Copperbelt

(Figure 2.4). Although the deposit was considered by Wakefield (1978) to be a metamorphosed porphyry copper deposit, recent work has demonstrated that mineralization took place between 490 and 460 Ma

(M. Hitzman, unpub. data, 2006), thus making it one of the youngest copper deposits known in the

Central African Copperbelt.

Copper occurrences are also known within the Upper Roan Subgroup carbonate sequence above the Mufulira deposit, apparently at the approximate stratigraphic level of the Mines Subgroup deposits in the DRC, but no economic deposits have yet been located within this interval in the Zambian Copperbelt.

Important deposits (Frontier and Lonshi) are present in the uppermost Mwashya Subgroup and basal

Nguba Group (Grand Conglomérat, lower Kakontwe Limestone) on the eastern edge of the Zambian

Copperbelt (Figure 2.3 and Figure 2.4). These deposits occur where the Roan sequence is condensed and the Copperbelt Orebody Member is depositionally absent.

The Fishtie (Kashime) deposit to the southeast of the Zambian Copperbelt (Figure 2.1) contains disseminated sulfides within the Grand Conglomérat, in a location where the underlying Roan sequence is condensed and, in places, the Grand Conglomérat lies directly on basement. Sulfide textures are remarkably similar to those in the giant Kamoa deposit nearly 500 km to the northwest on the western edge of the Congolese Copperbelt (Hendrickson, 2013).

The most typical sulfide assemblage in all of the Zambian Copperbelt deposits is chalcopyrite- bornite with subsidiary chalcocite and pyrite. Carrollite is widespread in the western deposits although cobalt is present in economic quantities only in some of these. Textures of ore sulfides are controlled by 16 both sedimentary fabrics and deformational features. Copper sulfides are most commonly found within interstitial sites between detrital and secondary (authigenic) minerals, as replacements of diagenetic pyrite, anhydrite, or heavy minerals such as rutile (Binda, 1975; Fleischer et al., 1976), and within pre- folding, layer-parallel veins (Annels, 1989) and late tectonic veins (Sillitoe et al., 2010). The Zambian

Copperbelt contains volumetrically minor Cu-U-Mo-(Au)-(Ni) sulfide assemblages in post-folding veins with associated albite haloes. The complex textural relationships of sulfides in the deposits within the

Copperbelt Orebody Member suggest multistage ore formation (Selley et al., 2005).

Vertical and lateral sulfide zonation characterizes many Zambian deposits, particularly the argillite-hosted deposits (Mendelsohn, 1961a; Fleischer et al., 1976). Most deposits have bornite (± chalcocite) at their base grading upwards to chalcopyrite and finally pyrite. Laterally the deposits are zoned over distances of ~100 m to several kilometers, from bornite (± chalcocite), through chalcopyrite (± carrollite), to distal pyrite (± pyrrhotite, local minor sphalerite). Arenite-hosted orebodies exhibit similar sulfide zoning.

The Zambian Copperbelt is characterized by stratigraphically and laterally widespread metasomatism indicative of a protracted, complex history of basinal brine migration (Darnley, 1960;

Selley et al., 2005). In general the major alteration stages proceeded from early magnesian (anhydrite, dolomite, magnesite, Mg-chlorite and tourmaline), locally with significant albitization and silicification

(J. Woodhead, unpub. data, 2011), through widespread potassic (K-feldspar and local sericite), to late- stage structurally controlled sodic (vein-associated albite).

Potassic alteration is widespread within the Lower Roan Group (i.e., sub-salt) and broadly associated with at least some copper sulfide precipitation. Sodic alteration dominates in rocks of the

Upper Roan and Mwashya subgroups and in the lower Nguba Group, at and above the interpreted level of former salt. Sodic alteration is also locally important in some so-called footwall arenite-hosted deposits

(e.g., Chibuluma; Selley et al., 2005), especially where the host rocks for the deposits are in hangingwall contact with Roan megabreccia. Wallrock albitization accompanies ~500 Ma post-folding veins that remobilized earlier-formed stratiform ore sulfides (Chambishi Ore Shale, Jolly, 1971; Musoshi Ore Shale, 17

Lefebvre and Tshiauka, 1986; Richards et al., 1988a), or that introduce minor late U-Mo-Cu-(Au) (e.g.,

Mindola, Darnley et al., 1961). Sodic alteration is the main alteration phase at the Frontier deposit.

Most of the orebodies have undergone supergene oxidation. The depth of supergene weathering in the deposits varies widely, with some development of copper oxides and carbonates, together with secondary chalcocite, to depths of almost a kilometer along faults.

2.2.3 Konkola-Musoshi deposit

The argillite-hosted Konkola-Musoshi deposit straddles the Zambia-DRC border and is the single largest deposit in the Zambian Copperbelt (Figure 2.4). It comprises several orebodies previously considered as separate, but now known to be continuous (Figure 2.5). These occupy a northwest-trending and broadly fault-controlled belt stretching from the Konkola deposit (historically Bancroft, Schwellnus,

1961; Sweeney and Binda, 1989; Torremans et al., 2013) to Konkola Deep and Konkola North (ARM,

2011) to Musoshi in DRC (Richards et al., 1988a, b). The orebodies occur between the Kiralabombwe and Konkola basement domes, which form two anticlines offset at depth in a right-lateral sense. The northern limb of the anticline at Konkola coincides with a sharp change in thickness in the Mindola

Clastics Formation, which is very thin along the northern flank of the Kirilabombwe dome and thickens in the deposit area and anticline to approximately 800 m. The southern limit of ore at Konkola coincides approximately with the northwest-trending Fitwaola fault.

The small Fitwaola orebody southeast of Konkola may be the relict of a much larger pre- erosional mineralized body. The surface traces of the stratigraphic units are constrained by mapping, drill hole data, and geophysical data. The Konkola-Musoshi deposit occurs within and adjacent to two basement-cored anticlines characterized by exceptional thicknesses of rift-stage coarse siliciclastic sedimentary rocks of the Lower Roan Subgroup. The Konkola orebody occurs within a northwest- plunging anticline. The northern boundary of the orebody coincides with an abrupt reduction in thickness of Lower Roan Subgroup rocks and eastward pinchout of the Ore Shale interpreted to mark a northwest- trending syn-sedimentary growth fault (Lubengele fault). The southern boundary of the orebody is 18

!"# $

0 )1 -) & , .& ' - & ' +''&" & ',&)) +''&" & ' &" & ' &" & '( ) &* % / ,'

Figure 2.5: Simplified geological map of the Konkola-Musoshi deposit area, with surface projection of the Ore Shale orebodies at Konkola, Konkola North and Musoshi. The location of the Konkola area is shown in Figure 2.4.

marked by the similarly oriented Fitwaola fault, which parallels a major synclinal structure with northern and southern limbs that contain markedly different thicknesses of Lower Roan basal conglomerate. The westward extensions of these faults below younger rocks are poorly constrained. The orebodies at

Konkola North and Musoshi occur within and on the northern flank of an east-plunging anticline. At

Konkola North, the southern limit of economic mineralization in the Ore Shale approximately coincides with the pinch-out of basal conglomerate, thought to represent a syn-sedimentary growth fault. The saddle area between the two anticlines and Konkola and Konkola North contains drill-defined mineralization at depths of up to 1600 m (Konkola Deep orebody), which links the shallower orebodies across the regional

19 trends of the two anticlines.

Adjacent to the Konkola dome, the southern boundary of the Konkola-Musoshi deposit coincides approximately with a marked thickness change in the Mindola Clastics Formation, here inferred as a syn- depositional fault. The northern boundary is poorly defined, as the down-dip extent of mineralization at

Musoshi is not known.

Other features of the ore distribution at Konkola may be structurally controlled. A high-grade zone occurs at Konkola along the crest of the anticline and is faulted. A barren gap between the northern and southern parts of the Konkola orebody coincides with a facies change from dolomitic siltstone to sandstone (Figure 2.5; Selley et al., 2005) and is likely related to syn-sedimentary faulting. There appears to be a direct relationship of high-grade zones to faults in the Konkola Deep area (Wilton, pers. comm.,

2009) and to now-inverted faults on the eastern flank of Konkola (Torremans et al., 2012).

Sulfides at Konkola occur throughout the Copperbelt Orebody Member but are concentrated in dolomitic siltstone intervals (Sweeney et al., 1986). Minor amounts of sulfide are also found in conglomerates of the uppermost Mindola Clastics Formation. The general paragenetic sequence of major ore minerals is carrollite-chalcopyrite-bornite-chalcocite (Sweeney et al., 1986).

The dolomitic siltstones of the Copperbelt Orebody Member in the Konkola deposit have high

K/(Al-Na) ratios (Moine et al., 1986) and this is observed to be due to the presence of abundant microcystalline K-feldspar. This secondary K-feldspar occurs as early (precarbonate and anhydrite cement) overgrowths on detrital K-feldspar (Sweeney and Binda, 1989) and partial to complete replacements of detrital plagioclase (Selley et al., 2005). The host rocks also contain less abundant fracture-controlled secondary K-feldspar. Sulfides are commonly intergrown with the secondary feldspar suggesting simultaneous precipitation.

2.2.4 Mufulira deposit

Mufulira is the largest known arenite-hosted deposit in the Zambian Copperbelt. The deposit consists of three stacked orebodies that are successively smaller upsection (Figure 2.6; Maree et al., 20

1961). The largest orebody (C orebody) has a strike length of approximately 5.5 km, a width of 1.3 km and averages about 14 m thick. Each of the orebodies is capped by an up-section facies change from arenite to less permeable shale or dolomite. The Mufulira deposit appears to have originally occupied a broad, low-amplitude anticline (Annels, 1979) that resulted from inversion of a subbasin containing rocks of the Mindola Clastics Formation, a geometry similar to that of an anticline-hosted hydrocarbon trap.

! "" # $ % $ % $ & ' & " & () " "* +

Figure 2.6: Cross section through the Mufulira deposit (along the 27-28 block boundary). The deposit consists of three stacked orebodies (C, lowermost, B, and A) within sandstones of the Lower Roan Subgroup. The orebody occurs above a small graben developed in the Mindola Clastics Formation of the Lower Roan Subgroup. Each of the orebodies is overlain by rocks with low relative permeability compared to the host sandstones. The rocks hosting the deposit currently dip eastwards off the Kafue Anticline but isotopic evidence suggests the Mufulira deposit consisted of a physical hydrocarbon trap at the time of formation (Selley et al., 2005). Cross section based on Zambia Consolidated Copper Mines Ltd. mine records and Groen (1961). The location of the Mufulira deposit is shown in Figure 2.4.

The Lower Roan Group quartzites in the Mufulira area contain minor disseminated carbonaceous matter in primary or secondary porosity that gives them a dark grey to almost black color (Brandt et al.,

1961; van Eden, 1974). Carbonaceous zones transgress bedding and, therefore, are postdepositional

(Annels, 1979). The distribution of the carbonaceous matter suggests it was introduced as mobile hydrocarbons into arenite reservoirs (Annels, 1979).

Sulfides in the Mufulira deposit are broadly zoned with bornite (± chalcocite) at the base of individual orebodies, through chalcopyrite, to pyrite at the top (Brandt et al., 1961). Mufulira is unusual for Zambian Copperbelt deposits in having a distinct zinc-rich fringe to the northwest where several percent sphalerite is disseminated with pyrite in beds equivalent to those that host the lowermost orebody

(Fleischer et al., 1976; Unrug, 1988).

Ore sulfides at Mufulira generally occupy interstitial sites between detrital grains. The sulfides may occupy primary or secondary porosity and/or replace diagenetic cements such as quartz, anhydrite, and carbonate and carbonaceous matter. Sulfides generally display an antithetic relationship to disseminated and nodular anhydrite (Garlick and Fleischer, 1972; Annels, 1974), which is rare in the orebodies but abundant in their peripheries (Annels, 1979).

Unlike the Konkola deposit that contains abundant secondary K-feldspar, the quartzites at

Mufulira are nearly barren of K-feldspar but contain abundant fine-grained muscovite (sericite) (Darnley,

1960). The mineralized rocks at Mufulira also display a paucity of chlorite, anhydrite, and dolomite relative to laterally and vertically equivalent arenites that contain subeconomic grades of copper (Darnley,

1960; Brandt et al., 1961; Fleisher et al., 1976; Annels, 1979). The spatial association of sericite with sulfides at Mufulira suggests they may be genetically linked. Formation of sericite at the expense of K- feldspar (and Ca- and Mg-bearing phases) at Mufulira may be due to acid generation during ore-stage oxidation of large volumes of sour gas (Selley et al., 2005).

2.2.5 Frontier deposit

The Frontier deposit (previously known as Lufua) is located in the DRC on the east flank of the

Kafue anticline, ~30km southeast of Mufulira (Figure 2.4). The orebody occurs in an area where the

Lower Roan Subgroup is condensed, such that the Copperbelt Orebody Member and the broadly stratigraphically equivalent Mufulira ore-bearing sandstones are absent. Mwashya Subgroup shales form the stratigraphically (and structurally) lowest reduced unit in the local section and are the host for the majority of the sulfides. The Mwashya Subgroup shales are overlain by largely unaltered and 22 unmineralized conglomeratic schist (Grand Conglomérat) that contains pebble-sized and rounded clasts of sandstone, siltstone, basement schist, quartz, and rare dolomite within a dark biotitic to calcareous or dolomitic muddy matrix.

( ! ")) "'' " & $!! ! ! "# ( !, ( !( "* ' + - ')."! % & ! ' /!0" ) !1

Figure 2.7: Frontier deposit. a) Simplified geological map of the Frontier deposit area. The deposit occurs between two originally syn-sedimentary normal faults that were reactivated during basin inversion. Though not obvious from this map view, the normal faults controlled the thickness of sediments in the Katangan sequence and appear to have been active during deposition of both the Mwashya Subgroup shales and the Nguba Group Grand Conglomérat. The location of23 ' #. the section line 4 is shown. b) Simplifed cross-section through the Frontier deposit. The deposit occurs within shales in the upper portions of the Mwashya Subgroup and within the base of the Nguba Group. The deposit is structurally controlled with sulfides in veins and irregular replacements adjacent to a major recumbent fold nucleated along the originally normal faults. The location of Frontier is shown in Figure 2.4.

The approximately 2 km-long deposit is bounded by strike-parallel NNW-trending and oblique transfer faults (Figure 2.7). Inversion of these faults during Lufilian deformation probably formed the complex recumbent folds that host the orebody. The orebody consists of a complex network of stockwork to breccia veins that contain an assemblage of dolomite-quartz-chalcopyrite ± bornite. Veins range in width from millimeters to almost half a meter. Thicker veins commonly contain angular clasts of adjacent wallrock. Minor sulfides occur as disseminations in wallrocks adjacent to veins. The sulfide- bearing veins are surrounded by a zone with tan to orange colored albite replacement of the wallrocks.

Such albitization may extend centimeters to meters from individual veins. Replacive dolomite, some ferroan, is found peripheral to the zone of albitization and may extend tens of meters from veins. Calcite veins occur outside of zones with ferroan dolomite.

Veins and altered wallrocks were deformed by folds. The folding event also produced a weak cleavage into which the sulfide minerals were locally remobilized. The earliest alteration-mineralization therefore predates the earliest recognizable folding in the rocks. Mineralized rocks are cut by late calcite veins that contain clasts of earlier dolomite-quartz-sulfide veins and albitized wallrocks.

2.2.6 Lonshi deposit

The Lonshi deposit is located in the DRC along the eastern side of the Kafue anticline, ~70km southeast of Frontier (Figure 2.4). Sulfides occur along the contact between a diamictite (termed the

Lonshi Conglomerate) presumed to be the Grand Conglomérat and overlying dolomites similar to the

Kakontwe Dolomite. The diamictite contains rounded clasts of sandstone, siltstone, basement schist, quartz, and rare dolomite in a dark calcareous/dolomitic muddy matrix. The unit is less deformed and foliated than the diamictite at Frontier.

The orebody is bound by two steeply dipping, northwest-trending faults, adjacent to which bedding is steep to overturned. The faults contain hematite with trace chalcocite. The orebody mined in the open pit consisted primarily of weathered mineralized Kakontwe Dolomite hosting tenorite, lesser malachite, and native copper. Locally unoxidized zones contained disseminations and discontinuous 24 sulfide-(dolomite-quartz) veinlets primarily of chalcopyrite with lesser bornite. Very minor albitization of the dolomite occurs locally around some veins.

Sulfides also occur within the Lonshi Conglomerate. The sulfide assemblage is zoned downward from the dolomite contact in the series chalcocite-bornite/covellite-chalcopyrite-pyrite; chalcocite and covellite appear to be largely supergene in origin. Sulfide textures in the diamictite consist of blebs, disseminations, and replacement of carbonate clasts. Fine-grained alteration minerals in the diamictite include interstitial and replacement hematite-carbonate-anhydrite. Irregular zones of tan to orange albite are present but pervasive albitization, as found in the Frontier deposit, does not occur.

2.3 Congolese Copperbelt

The Congolese Copperbelt forms an arcuate ~350 by 50 km belt, from the Kimpe deposit

adjacent the Luina basement dome just north of the Zambian Copperbelt to the Kolwezi district

adjacent the Nzilo basement block in the northwest (Figure 2.8). There are no known basement rocks

within the limits of this belt.

2.3.1 Stratigraphy

The Roan Group of the Congolese Copperbelt is subdivided into four subgroups forming two major stratigraphic cycles or sequences (Cailteux, 1994): the R.A.T. (R-1) and Mines (R-2) subgroups, and the Dipeta (R-3) and Mwashya (R-4) subgroups (Figure 2.2) (François, 1973, 1974, 2006; Cailteux,

1994; Cailteux et al., 2005a, b; Kampunzu et al., 2005). The basal unit of the exposed Roan Group in the

DRC is the R.A.T. Subgroup (Figure 2.2), which in its uppermost, best-studied part (R1.3) contains generally reddish, hematitic, commonly indistinctly stratified siltstones and fine-grained sandstones.

These rocks are quartz-poor and rich in Mg, with abundant dolomite, magnesite, Mg-chlorite, and talc (Cailteux et al., 2005b). This unusual composition has been interpreted as indicative of an evaporative

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Figure 2.8: Map of the Congolese Copperbelt in the main Katangan basin showing the location of R.A.T., Mines, and Dipeta subgroup rocks and location of major deposits. Modified from Jackson et al. (2003). 26 depositional environment and/or extreme metasomatism (Cluzel, 1985; Moine et al., 1986; Kampunzu et al., 2005), consistent with its position below the highly evaporitic beds of the Kamoto Formation. Deeper parts of the R.A.T. Subgroup are preserved in the Kolwezi district where up to 230 m of the unit have been intersected in drill holes. These rocks are distinctly stratified, containing dolomites, sandstones, and purple-striped siltstones (François, 1973). The base of the R.A.T. Subgroup is everywhere truncated against breccia, which resembles monolithic to polylithic conglomerate but is considered to represent tectonically mobilized evaporite. The uppermost part of the R.A.T. in many areas is grey and sulfide- bearing but otherwise indistinguishable from the underlying rocks with which it is transitional (Cailteux,

1994).

The overlying Mines Subgroup contains the majority of deposits and is subdivided into three major units: the Kamoto (R-2.1), Shales Dolomitiques or S.D. (R-2.2), and Kambove or C.M.N. (Calcaire

à Minerai Noir; R-2.3) formations. The base of the Mines Subgroup is placed at the base of the D. Strat.

(Dolomies Stratifiées) unit of the Kamoto Formation. This unit marks a major lithological change and a marine transgression (Cailteux, 1994). The D. Strat. unit contains finely bedded impure and variably silicified dolomites, commonly with casts after evaporitic minerals and centimeter-sized elliptical siliceous nodules. The overlying R.S.F. (Roches Siliceuses Feuilletées) unit is lithologically similar but with reduced bed thicknesses of millimeter-laminated siliceous dolomites of probable algal origin, a lack of nodules, and a progressive increase upsection in the intensity of silicification. The D. Strat., R.S.F., and locally the uppermost grey-colored R.A.T. units, are the most common economically mineralized interval within the Congolese Copperbelt.

The R.S.F. unit is sharply overlain by the R.S.C. (Roches Siliceuses Cellulaires) unit that forms the top of the Kamoto Formation. It is composed mainly of pervasively silicified, massive to stromatolitic carbonate rocks with casts after evaporite minerals and minor interbeds of non-silicified siltstone; it is resistant and typically crops out. The R.S.C. unit averages 30 m in thickness but thins to both the north and south of the axial trend of the Congolese Copperbelt.

The transition from the R.S.C. unit to the overlying S.D. Formation is generally abrupt, with silicified carbonate passing upsection into fine-grained, parallel-stratified, locally nodular and dolomitic, non-silicified siltstone. The S.D. Formation consists of variably carbonaceous shales and dolomitic siltstones having a typical thickness of 70 – 80 m; this formation contains the maximum flooding surface in the Mines Subgroup. The ratio of sandstone to dolomitic siltstone in the S.D. Formation increases progressively northwards from the axial portion of the Kolwezi district (François, 1973), whereas to the south the S.D. Formation is less dolomitic and contains more carbonaceous siltstones.

Although the Kamoto Formation and lower Dolomitic Shales Formation exhibit remarkable stratigraphic regularity across the Congolese Copperbelt, there are subtle lithofacies variations along and across the district, which broadly correlate with the distribution of mineralized zones (François 1973,

1974, 2006; Cailteux, 1983, 1994; Cailteux et al., 2005a). François (1973, 1974, 2006) utilized variations in the thickness and stromatolitic facies type of the R.S.C. unit and the ratio of subarkosic sandstone to dolomitic siltstone in the S.D. Formation to define five lithofacies within and adjacent to the Kolwezi district, only two of which contain major ore deposits.

A marine regression followed deposition of the S.D. Formation and resulted in formation of sub- tidal to evaporitic inter- to supra-tidal carbonates in the lower part of the Kambove Formation (Figure

2.2). A second transgression during deposition of the Kambove Formation resulted in a return to either sub-tidal carbonates or dolomitic siltstones. The upper Kambove Formation records another regression with a return to locally evaporitic, silicified, and commonly weakly mineralized intertidal carbonate rocks. The Kambove Formation is typically 190 m thick.

The base of the overlying Dipeta Subgroup comprises hematitic, argillaceous dolomitic siltstones,

sandstones, and locally conglomerates of the R.G.S. (Roches Gréso-Schisteuses) unit (Figure 2.2). The

R.G.S. unit represents an abrupt sea level regression or basinward shift of facies to siliciclastic rocks

similar to those of the R.A.T. Subgroup and is considered to represent a sequence boundary (Bull,

unpub. data, 2010). The upper portions of the Dipeta Subgroup contain evaporitic lagoonal deposits,

stromatolitic carbonate units, and deeper water dolomitic shales and siltstones that formed in similar 28

regressive and transgressive sedimentary cycles to the sediments of the Mines Subgroup. The Dipeta

Subgroup is overlain by the Mwashya Subgroup, a heterogeneous sequence of dolomitic shales and

siltstones, carbonaceous siltstones, and minor sandstones.

The Roan Group in the Congolese Copperbelt is overlain by sedimentary rocks of the Nguba and

Kundelungu Groups (Figure 2.2), which have a combined thickness of several kilometers. The Grand

Conglomérat unit at the base of the Nguba Group generally thickens southward from the northern to the

central part of the Congolese Copperbelt (François, 1973). The Grand Conglomérat is overlain by

massive carbonate rocks (Kakontwe Limestone; Cailteux et al., 2007) or carbonate-bearing to carbonate-

poor siltstones and sandstones that fine from dominantly sand- and siltstones in the north to shales in the

south (Batumike et al., 2006) and appear to represent shallow marine to fluvial sediments. The

remainder of the Nguba Group consists of dolomitic sandstones and siltstones with detrital grain size

generally decreasing and carbonate content increasing southward within the main Katangan basin

(Batumike et al., 2006, 2007).

2.3.2 Salt tectonic disruption of the Mines Subgroup

Rocks of the R.A.T., Mines, and Dipeta subgroups in the DRC are known only as blocks

(écailles) that occur within stratiform to discordant and diapiric megabreccias with a gravel- to silt-sized

matrix of talc, dolomite, quartz, and Mg-rich chlorite. Blocks within the megabreccias range in size

from tens of meters to several kilometers in length, and appear to grade downward into sub-meter and

centimeter-sized fragments. Large blocks commonly occur on the edges of megabreccia, but may also

be contained, or float within it. The megabreccias may also contain blocks of Nguba and Kundelungu

group rocks where they cut these units. The megabreccias are interpreted to have been derived from the

mobilization of Roan Group evaporites, including gypsum-anhydrite and halite (Demesmaeker et al.,

1963; François, 1974, 2006; DeMagnée and François, 1988; Kampunzu and Cailteux, 1999; Jackson et

al., 2003) (Figure 2.9).

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Figure 2.9: Model for the formation of diapiric breccias and megabreccias in the Central African Copperbelt. In the Main Katangan basin of the Congolese Copperbelt, which contained thick evaporite sequences, blocks of R.A.T., Mines, and Dipeta subgroup were rafted upward with the salt, resulting in juxtaposition with much younger stratigraphic units. The majority of blocks are vertically oriented; Kolwezi is an exception. In the Zambian Copperbelt mineralization took place largely below the level of salt. Salt flow in this area does not appear to have formed significant diapiric structures, perhaps due to much thinner evaporite sequences. It is unclear if lithostatic load from the overlying sediment pile or tectonic loading during basin inversion was primarily responsible for initiation of salt diapirism.

Systematic variations in the thickness of the Grand Conglomérat on opposite limbs of Roan megabreccia-cored anticlines suggests that diapiric movement of evaporites was underway by early

Nguba Group time and was controlled by growth faults active during sedimentation (D. Selley, unpub. data, 2012). Rapid deposition of the Grand Conglomérat may have provided the necessary loading to initiate halokinesis. Megabreccia containing Mines Subgroup blocks was commonly emplaced upon a

30 specific stratigraphic level of the Kundelungu Group, the Ku 2.1 unit, indicating that salt movement occurred up to the time of deposition of the upper Kundelungu Group and probably continued into the period of Lufilian deformation (Jackson et al., 2003).

The broad facies patterns observed in and between blocks of the Kamoto Formation and the

Dolomitic Shales Formation within the megabreccia demonstrate that while this sequence was locally structurally disrupted during formation of the megabreccia, the overall facies pattern was relatively unchanged by megabreccia formation and subsequent Lufilian orogenesis. This argues against the need for regional-scale northward transport of Mines Subgroup rocks as proposed by numerous authors, including Kampunzu and Cailteux (1999), Porada and Berhorst (2000), and Wendorff (2000a).

2.3.3 Copper-cobalt deposits

The majority of the deposits in the Congolese Copperbelt, such as those in the Kolwezi and

Tenke-Fungurume districts, occur as blocks within megabreccias. Mineralized (and unmineralized) blocks range from hundreds of meters to over a kilometer in length. The blocks are commonly folded and faulted and typically have complex geometries (e.g., Kwatebala; Schuh et al., 2102).

Most deposits are hosted in the Kamoto (lower orebodies) and lower S.D. (upper orebodies) formations, separated by the generally poorly mineralized R.S.C. unit. Upper orebodies usually occur within the two lowest members of the S.D. Formation, termed the S.D.1a (Shales Dolomitiques de Base or S.D.B.) and the S.D.1b, a coarse grained, impure dolostone (Black Ore Mineralized Zone or

B.O.M.Z.). At some deposits, copper sulfides extend into overlying carbonaceous shales. The cumulative thickness of the stratigraphic interval encompassing the orebodies and R.S.C. unit varies from 15 to 55 m and averages about 25-30 m.

The Kamoto and S.D. formation rocks hosting the deposits throughout the Congolese Copperbelt underwent a complex history of secondary (diagenetic/hydrothermal) mineral growth, here termed alteration, which occurs regardless of tenor of mineralization and, as in the Zambian Copperbelt, is only broadly linked to ore formation. A generalized sequence of alteration within the Kamoto Formation, and 31 to a lesser degree the lower S.D. Formation is: (1) precipitation of diagenetic framboidal pyrite, (2) early potassic alteration leading to the formation of potassium feldspar in argillaceous and siliciclastic lithologies, (3) early carbonate (principally magnesite, at least at Kolwezi) crystal growth in carbonate and argillaceous carbonate lithologies and formation of Mg-chlorite in more argillaceous lithologies, (4) precipitation of microcrystalline quartz leading to silicification of the host rocks, (5) precipitation of prismatic inclusion-rich quartz ± carbonate, generally dolomite, (6) precipitation of fine-grained, generally disseminated Cu-Co sulfides + quartz ± dolomite, and (7) formation of coarse-grained disseminated and vein-controlled dolomite ± quartz ± Cu-Co sulfides (Oosterbosch, 1951; Bartholomé et al., 1972; Hoy, 1989; Dewaele et al., 2006; El Desouky et al., 2009, 2010; Fay and Barton, 2012).

Regionally, intense silicification of the Kamoto Formation persists well south of the main zone of deposits, within barren Mines Subgroup blocks hosted by megabreccia (François and Cailteux, 1981).

Framboidal and early pyrite are preserved within the orebodies where these minerals were mantled by authigenic gangue minerals or carrollite; otherwise early pyrite appears to have been replaced by copper sulfides (Bartholomé et al., 1972; Hoy, 1989). Copper- and cobalt-bearing sulfides precipitated late in the alteration sequence. They occur as disseminated grains, commonly along stratification, within modified primary porosity and secondary pore space generated by selective dissolution or replacement of carbonate, evaporite, and possibly detrital and diagenetic minerals, as apparent open-space fillings generated by stratal collapse, and in bedding-parallel and oblique veinlets, some of which display distinctive fiber textures (Bartholomé, 1974; Hoy, 1989; Cailteux, et al., 2005b; Dewaele et al., 2006; Fay and Barton, 2012). Carrollite generally predates chalcopyrite and bornite.

Ore sulfide zonation in the Mines Subgroup orebodies is complex and occurs at multiple scales.

There is commonly a crude vertical chalcocite-bornite-chalcopyrite-pyrite zonation from the lower through the upper orebody, and a distinct association of carrollite (and in some orebodies, chalcocite) adjacent to and within the intervening R.S.C. unit. Individual mm/cm-scale beds provide a local control on sulfide mineralogy and zoning, particularly within the lower orebody. For example, the R.S.F. unit contains alternating silicified dolomite and micaceous laminae with sulfides occurring preferentially 32 within the dolomitic laminae (Hoy, 1989) that may be mineralogically zoned relative to bedding. At the grain scale, Cu-poor sulfides usually are mantled by Cu-rich sulfides, typical of vertically zoned sedimentary copper deposits, but local reversals also suggest overlapping zonation patterns, in space and probably in time.

Recent investigations at Kamoto and Luiswishi highlighted two distinct stages of ore sulfides: an early, fine-grained stage characterized by lenticular, pre-lithification nodules and a later, coarse-grained stage with post-lithification, locally discordant nodules and veins (El Desouky et al., 2009, 2010). These stages and their associated gangue minerals also are characterized by distinct S, C, and Sr isotopic signatures, and by different temperatures and salinities of formation (El Desouky et al., 2009, 2010).

Not all Mines Subgroup blocks within the megabreccias are economically mineralized. Even in megabreccias with well-mineralized Kamoto and S.D. formation blocks, immediately adjacent blocks representing the same stratigraphy may be poorly mineralized or barren (e.g., Tenke-Fungurume; Schuh et al., 2012). The limbs of disrupted anticlines or anticlinal fragments occurring as blocks in the megabreccia commonly differ in their Cu-Co content, such that one limb may be ore and the other waste.

This, together with the fact that stratabound alteration is present in the blocks regardless of sulfide content or disruption, strongly suggests that mineralization and alteration pre-dated significant dismemberment of the Mines Subgroup stratigraphy (Demesmaeker et al., 1963; François, 1973; Cailteux, 1994; Cailteux et al., 2005a).

Mineralization also occurred at stratigraphic levels above the Kamoto and S.D. formations.

Several orebodies, such as Kambove-Ouest, Luiswishi, and Luishia (Figure 2.8), have minor amounts of mostly oxidized ore in the lower part of the Kambove Formation (François, 1974), while the Kinsevere and Kisanfu deposits have relatively significant amounts of mineralized Kambove Formation rocks. A few small deposits and prospects occur in the Dipeta Subgroup (François, 1974) and the Mwashya

Subgroup (François, 1974; Lefevbre, 1974; Cailteux et al., 2007). Evaporitic and stromatolitic carbonate facies in these deposits exhibit similar, facies-selective alteration – in particular silicification – to deposits

33 in the Mines Subgroup. The major Kamoa deposit is found on the western edge of the main Katangan depocenter at the base of the Grand Conglomérat (Broughton and Rogers, 2010).

As in the Zambian Copperbelt (Selley et al., 2005), mechanisms for sulfide precipitation in the

Congolese Copperbelt were probably varied and included reduction by in situ (carbonaceous material, pyrite) or mobile (H2S, CH4, hydrocarbons) material, fluid mixing, replacement of reactive detrital or secondary minerals (e.g., carbonate, feldspar, rutile), and infilling of open space generated by fracturing, collapse, or prior dissolution. The association of ore with the lowermost reduced facies rocks in the stratigraphic section (generally pyritic and originally organic-rich algal and stromatolitic carbonates) strongly suggests reduction as the primary mechanism. The presence of abundant carbonaceous matter appears to have hindered the formation of ore sulfides, as highly carbonaceous, and typically pyritic, variants of the Kamoto and lower S.D. formations commonly are poorly mineralized.

The Congolese orebodies were affected by a period of supergene enrichment, probably during humid weathering in the Tertiary (Decrée et al., 2010; De Putter et al., 2010). Chalcocite-malachite and locally chrysocolla are most abundant near surface and pass downward into chalcocite-rich assemblages.

Near-surface grades in well-mineralized blocks within the megabreccia commonly average between 4 and

6% Cu, whereas deeper, less oxidized intersections average approximately 3% Cu. To date, most mines in the Congo have exploited primarily high-grade oxidized material. Leached copper caps are locally developed but cobalt was less mobile than copper and commonly forms near-surface high-grade zones

(Fay and Barton, 2012).

2.3.4 Kolwezi district

The largest deposit cluster hosted within the Mines Subgroup occurs within the Kolwezi district, which contains nearly half of the known Mines Subgroup-hosted Cu-Co resources in the Congolese

Copperbelt (Hitzman et al., 2005). The district consists of a northeast-trending synclinal accumulation of up to 1.2 km vertical thickness of Roan megabreccia containing Mines and Dipeta subgroup blocks, overlying Kundelungu Group (Ku 2.1) strata across a basal zone of breccia (François, 1973). It is widely 34 interpreted as one of several klippen, relict from a large, folded allochthonous sheet along the western limit of the Congolese Copperbelt, adjacent to the Nzilo basement block (Demesmaeker et al., 1963;

François, 1973; Jackson et al., 2003).

Within the district, most Mines Subgroup blocks are gently dipping monoclines or near- recumbent tight to isoclinal anticlines with relatively little complex folding (Figure 2.10). Across the axis of the Kolwezi klippe there is a general symmetry of inward-dipping écailles and dismembered folded

écailles (François, 1973). Based on the distribution of the lithostratigraphic facies defined by François

(1973, 1974, 2006), we interpret this broadly symmetrical architecture to have been inherited from a pre- orogenic array of extensional faults that controlled facies deposition.

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Figure 2.10: Generalized geological cross section through the Kolwezi district (after François, 1973). Only some of the blocks of Mines Subgroup rocks are well mineralized. This geometry is thought to be derived from salt extrusion onto the surface (Jackson et al., 2003), although it is also permissive of derivation from a salt weld immediately below the district (e.g., Cailteux, 1990).

Deposits within the Kolwezi district have been exploited through a number of open pits and one major underground operation (Kamoto). The majority of material mined to date has been supergene enriched and contains malachite and copper oxides, together with relatively abundant chalcocite.

2.3.5 Tenke-Fungurume district

The Tenke-Fungurume district (Oosterbosch, 1951; François, 2006; Fay and Barton, 2012; Schuh et al., 2012) comprises a large expanse of exposed Roan Group rocks at the junction of several NW-SE to

E-W Roan-cored anticlines. The district occurs at the northern end of a major NW-trending anticline that hosts numerous significant deposits from Kakanda and Kambove to Luishia, Luiswishi, and Étoile

(Figure 2.8).

The southeast boundary of the district is marked by a NE trending fault (“faille de Fungurume” in

François, 2006), interpreted as a diapir edge or salt weld, that truncates the Kakanda anticline. The southern part of the Tenke-Fungurume district occurs at the junction of megabreccia-cored anticlines intersecting from the west (Pumpi area) and southeast (Kakanda anticline) (Figure 2.8) and contains abundant Mines Subgroup blocks in megabreccia. The south-central portion of the district is dominated by the ~20 km-long, east-west trending Dipeta Syncline, which is apparently upright and tight to isoclinal

(Schuh et al., 2012); there is an axial zone of Dipeta Subgroup rocks flanked on its long axes by relatively undisturbed and consistently inwards-facing Mines Subgroup blocks. The syncline closes to the west

(Tenke-Goma area) and east (Fungurume area) with clusters of more chaotically oriented blocks, particularly at Fungurume. Some of these blocks continue relatively intact to depths of at least 1800 m

(e.g., Figures 28-36 in François, 2006). The steeply dipping limbs culminate upward into dominantly flat- lying, mushroom-shaped caps (Figure 2.9; Kwatebala deposit; Schuh et al., 2012) that contain multiple, complexly stacked blocks.

The overall morphology of the southern part of the district is therefore one of a central syncline flanked by diapiric areas with steep-limbed and complexly stacked blocks. Vertical relief on the limbs

36 appears to have been on the order of 2 km or more. These diapiric areas may originally have linked to the regional anticlines, prior to dislocation across the Fungurume fault.

Not all megabreccia-hosted blocks within the Tenke-Fungurume district are economically mineralized; however, they all display broadly similar alteration styles. Within the Tenke-Goma (west) and Fungurume (east) clusters only 5 of 12 and 3 of 9 blocks, respectively, are well mineralized. In the tight to isoclinal Kwatebala anticline in the middle of the district, the south limb is well mineralized, whereas the adjacent north limb is weakly mineralized (Schuh et al., 2012). These variations do not appear to be due to secondary processes (i.e., leaching). The east-west limbs of the Dipeta Syncline are only slightly disrupted by minor discontinuities, but some of these subtle breaks mark significant lateral changes in facies and the degree of mineralization. Poorly mineralized carbonaceous blocks are juxtaposed along strike with well-mineralized less-carbonaceous blocks. Thus, as François (1973) demonstrated at Kolwezi, facies variation appears to correlate with changes in mineralization.

2.3.6 Kinsevere

The Kinsevere deposit is located approximately 25 km northeast of the Luiswishi deposit (Figure

2.8), and contains ore in both the Kamoto and Kambove formations. Studt et al. (1908) noted mineralized rocks at Kinsevere but recent exploration has defined a major deposit. The deposit comprises three blocks located within a small, irregular NW-trending megabreccia-cored anticline. The blocks contain Kamoto and Kambove formations but the R.S.F. and R.S.C. units are absent. The central, ~600 m x ~200 m x 200 m block, Tshifufia, hosts most of the resources. The deposit displays two styles of mineralization: disseminated sulfides most apparent in dolomite beds, and volumetrically dominant bedding-parallel and bedding-oblique vein-hosted sulfides (Kazadi, 2012). Significantly for exploration, the presence of well- mineralized veins over stratal thicknesses of at least 200 m provides substantial tonnage within a relatively small écaille.

2.3.7 Kamoa

The Kamoa copper deposit is located approximately 25 km west of the Kolwezi district (Figure

2.8). The Kamoa deposit is adjacent to a regional north-northeast-trending and broadly south-southwest- plunging basement dome of Kibaran metasedimentary rocks, the Nzilo block. The eastern margin of this basement high marks the approximate boundary between an eastern, basinal sequence containing numerous, salt-derived megabreccias (the main Katangan depocenter) and a western, shallow-dipping and condensed, siliciclastic sequence (the Western Foreland of Key et al., 2001).

The Kamoa deposit occupies a stratigraphic redox boundary between older, generally hematitic sandstones and conglomerates of probable Mwashya Subgroup age deposited on basement, and grey diamictites with interbedded pyritic siltstones and greywackes of the Grand Conglomérat. The Kamoa deposit is similar in morphology, mineralogy, and mineral zoning to the argillite-hosted deposits of the

Zambian Copperbelt. The deposit displays a classical mineral zonation from chalcocite to bornite to chalcopyrite to pyrite-(sphalerite) with increasing stratigraphic height above the redox boundary. Copper sulfides occur as fine-grained disseminations in the matrix of the Grand Conglomérat and as coarse- grained rims and partial replacements of diamictite clasts; veins are rare. The mineralogy of both the footwall and host rocks of the deposit have been modified by K-Mg-Ca alteration (Schmandt, 2012) similar to that observed in the Zambian Copperbelt (Selley et al., 2005).

2.3.8 Kipushi

The Kipushi Cu-Zn-Pb-Ag deposit occurs in southeastern DRC adjacent to Zambia (Figure 2.8)

(Intiomale, 1983; Intiomale and Oosterbosch, 1974; De Magnée and François, 1988; Tshileo et al., 2003).

The Kipushi deposit is located on the northern limb of a northwest-trending anticline cored by megabreccia. The deposit is localized in, and within the immediate footwall of, the north-south trending

Kipushi fault, where the fault cuts dolomite and interbedded dolomite and carbonaceous shale of the lower Nguba Group. The orebody is copper-rich to the north where the footwall is shale, and zinc-rich to

38 the south where it is dolomite; there is also a general vertical trend from copper-rich at surface to zinc- rich with depth.

Sulfide mineralization at Kipushi was complex and multi-stage (Heijlen et al., 2008, and references therein). The main sulfide minerals at Kipushi are chalcopyrite, sphalerite, pyrite, bornite, and chalcocite, with lesser amounts of galena, arsenopyrite, tennantite, and renierite, and a suite of minor Fe,

Cu, Zn, and other sulfosalts (Intiomale and Oosterbosch, 1974; Lhoest, 1995). The deposit contains barium-rich celsian feldspar, hyalophane, and Ba-muscovite but lacks significant barite (Chabu, 1995;

Chabu and Boulègue, 1992). Ore textures include replacement of host rock, pre-metamorphic folded sulfide veins (which call into question the 450 Ma age of mineralization (Schneider et al., 2007)), sulfides intergrown with metamorphic minerals, and post-metamorphic vein-filling sulfides. Sulfides are locally intergrown with albite and phlogopite, suggesting pre- or syn-mineralization albitic and magnesian- potassic alteration. There are several stages of pre-and post-ore dolomite formation and an important, ore- stage quartz event (Heijlen et al., 2008). An amorphous, ungraphitized organic substance, occurs locally with sulfides; it was derived from hydrothermal alteration of migrated hydrocarbon (Francotte and

Jedwab, 1963; Melezhik et al., 1999; Heijlen et al., 2008). Mineralization at Kipushi is thought to have occurred when oxidized, metal-bearing fluids encountered a reduced, carbon-rich reservoir that was constantly replenished by a large amount of H2S (sour gas), probably derived from thermochemical reduction of seawater-derived sulfate (Heijlen et al., 2008).

2.4 North West Province, Zambia

The North West Province of Zambia hosts three major copper deposits (Kansanshi, Lumwana,

Sentinel) associated with basement domes mantled by Katangan rocks (Figure 2.11) (Unrug, 1988; Selley et al., 2005). Geological understanding of the area is limited by a lack of deep drill holes and locally intense deformation, metasomatism, and metamorphism, but available data indicate that the deposits are hosted in a stratigraphic sequence broadly analogous to that of the Zambian Copperbelt.

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Figure 2.11: Generalized geological map of the North West Province of Zambia (Domes region) showing the locations of the!"#$%&' major deposits. (( The apparent absence of significant Mwashya Subgroup and Nguba Group rocks in the eastern and western portions of the map area and the apparent predominance of Kundelungu Group rocks may be due to incomplete or inaccurate mapping. Geology of the Luiswishi dome area from Ayers (1975). Geology in the Solwezi Dome and Kansanshi area based on Arthurs and Legg (1974), Barron (2003), and data from First Quantum Minerals (2012a). Geology of the Mwombezhi Dome area from Mulelua and Seifert (1998) and Bernau (2007); geology of the Kabompo Dome area from Appleton (1978), Key et al. (2001), Klinck (1977), and data from First Quantum Minerals (2012b).

The domes are cored by ortho- and para-gneiss and schist correlated with the Palaeoproterozoic

Lufubu Metamorphic Complex in the Zambian Copperbelt (Rainaud et al., 2005). These basement rocks are overlain at the Mwombezhi dome (Figure 2.11) by structurally interleaved slices of siliciclastic and thin carbonate rocks, previously correlated with the Lower and Upper Roan subgroups (Cosi et al., 1992).

Possible correlatives of the Copperbelt Orebody Member occur at the Solwezi and Luiswishi domes, but the carbonaceous phyllites hosting the Sentinel (formerly Kalumbila) deposit adjacent the Kabompo

Dome – and previously interpreted as correlative (Steven and Armstrong, 2003) – are here considered to be Mwashya in age. In the Sentinel area it appears that evaporitic rocks similar to those of the R.A.T.

Subgroup in the DRC directly overlie basement rocks.

The Katangan Supergroup rocks in North West Province display a phyllitic to schistose texture with foliation subparallel to compositional layering. Greenschist facies to weakly metamorphosed equivalents of the Katangan Supergroup rocks occur within hundreds of meters of kyanite-talc whiteschists adjacent the domes, suggesting structural complexity and/or mobility of aluminum and unusual mineral growth during high-salinity metasomatism.

2.4.1 Copper deposits

The copper deposits in the North West Province occur throughout the stratigraphic succession from within or immediately adjacent to basement rocks (Lumwana) to the Mwashya-Grand Conglomérat interval (Sentinel and Kansanshi). Thus far, significant orebodies are not located at stratigraphic positions corresponding to those hosting the majority of deposits in the Zambian and Congolese Copperbelts.

2.4.2 Lumwana

Basement rocks in the Mwombezhi Dome mainly consist of quartz-feldspar-biotite gneiss and schist, granite gneiss, migmatitic gneiss, and amphibolite. In the vicinity of the Lumwana copper deposits, kyanite-bearing, hematitic micaceous quartzite and quartz-mica schist (Rimming Quartzite) probably represent metamorphosed red beds of the Lower Roan Subgroup (Figure 2.2). 41

Lumwana consists of two adjacent and similar deposits, Malundwe and Chimiwungo (Figure

2.11). Copper primarily occurs as coarse-grained chalcopyrite (>>bornite, cubanite, chalcocite) discontinuously disseminated within tabular bodies of strongly foliated quartz + muscovite + phlogopite/biotite ± kyanite schist (known locally as the Ore Schist; Bernau et al., 2007; Bernau, 2007;

Rowe, 2012); individual Ore Schist horizons are up to 40 m thick. Contacts with gneisses range from sharp to gradational.

Malundwe is the smaller but higher grade deposit, and has a strike length >4 km, a down dip extent of <1.4 km, and an average thickness of 14 m. North-south ore shoots parallel a mineral elongation

(stretching) lineation and the axes of low-amplitude, micro-to macro-scale folds in the schist. The Ore

Schist horizons occur above unmineralized, variably porphyroblastic schist (Footwall Schists) and below micaceous quartzite and quartz-mica schist derived from Lower Roan Subgroup rocks.

The Chimiwungo deposit, 8 km to the SE of Malundwe, consists of three main Ore Schist horizons separated by gneiss with an average total thickness of 60 m. The ore body strikes east-west, is up to 3.7 km wide, and extends 4 km down-dip. A series of late-stage, north-dipping, normal faults confine the mineralized interval to within several hundred meters of the surface.

Within the Ore Schists, copper sulfides are partitioned into micaceous shear zones characterized by significant depletion of Na and Ca, and possibly weak K ± Mg addition. Muscovite/sericite overprints earlier biotite/phlogopite, and deformation accompanying its growth is the main control on the present distribution of copper sulfides. Copper sulfide inclusions in kyanite porphyroblasts indicate that mineralization pre-dated peak metamorphism (Scott et al., pers comm., 2010).

2.4.3 Sentinel (Kalumbila)

The Sentinel deposit occurs east of the Kabompo Dome (Figure 2.11) within medium to dark grey, locally carbonaceous, commonly kyanite-bearing phyllite, previously correlated with the Ore Shale

(Steven and Armstrong, 2003) but currently thought to be part of the Mwashya Subgroup. The deposit occurs within a central, more carbonaceous phyllite relative to marginal more micaceous zones. The 42 phyllite is overlain by nearly massive to schistose to semi-gneissic feldspar-biotite (phlogopite)-quartz schists and gneisses interpreted as metasomatized Katangan Supergroup rocks. The phyllite is underlain by locally albitized heterogeneous biotite-phlogopite-feldspar-quartz-(kyanite) schists and minor carbonate rocks that also appear to be highly altered Katangan Supergroup rocks. Chalcopyrite, pyrite, and pyrrhotite occur as layer- and foliation-parallel veinlets and disseminations; bornite and chalcocite are rare. Foliation parallel kyanite-phlogopite-carbonate-quartz±talc veinlets are paragenetically young, discontinuous and contain sulfides. Chalcopyrite inclusions within kyanite indicate that at least some mineralization took place prior to metamorphism.

2.4.4 Kansanshi

The Kansanshi Cu-Au deposit (Broughton et al., 2002) north of the Solwezi Dome is hosted in strongly foliated and recumbently folded Mwashya Subgroup and lowermost Nguba Group rocks, including carbonaceous phyllites, porphyroblastic schists, and marbles, along a ~7 km strike length of the

NW-trending Kansanshi antiform, (Figure 2.12). Two essentially flat-lying orebodies in carbonaceous phyllites and lesser schists are separated by a marble unit. Mineralized zones contain steeply dipping, undeformed ~502 to 512 Ma quartz-dolomite/calcite-chalcopyrite (pyrrhotite/pyrite-molybdenite- uraninite-gold) veins, the earliest of which exhibits carbon- and biotite-destructive, albite-ferroan dolomite alteration haloes (Torrealday et al., 2000). Veins are of variable thickness from several centimeters to over 2 m. The veins are most abundant in the vicinity of 100s m-scale domes, which form topographic features along the crest of the Kansanshi antiform (Figure 2.12b). The main deposit high- amplitude dome has radial vein sets and while the low-amplitude northwest dome has orthogonal vein sets. In places an earlier, folded, bedding-parallel stage of disseminated chalcopyrite is present.

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Figure 2.12: a) Geological map of the Kansanshi area. The deposit occurs as a number of orebodies (indicated by the pits) along the crest of the Kansanshi Antiform. Sulfides occur primarily in Mwashya Subgroup phyllites and schists but also in the Grand Conglomérat (Pebble Schist). Orebodies contain high-angle veins that generally trend NE-SW and stratabound replacement zones adjacent to these veins. Note the presence of gabbro intrusions both to the north of the deposit and along the axis of the Kansanshi Antiform. b) Generalized cross section through the Main Pit of the Kansanshi deposit. The copper orebody occurs at the crest of the Kansanshi Antiform. Note the vertical repeat of the Grand Conglomérat and Kakontwe carbonate units. Unit repetition is due to large-scale recumbent folding that was probably associated with thrust stacking and dislocation along evaporite layers present in the underlying Roan Subgroup rocks. The location of the Kansanshi deposit is shown in Figure 2.11.

Supergene enrichment and subsequent partial oxidation of the upper parts of the deposit produced copper oxide and mixed copper oxide/chalcocite assemblages that have been the focus of recent mining.

In some areas the central marble is thin or absent due in part to dissolution of marble by supergene-

44 derived acidic fluids, and the two orebodies are combined. The depth to primary sulfide mineralization is fault and fracture controlled and highly variable, ranging from 200-300 to less than 10s of meters.

2.5 Common features of deposits in the Central African Copperbelt

The Central African Copperbelt contains significant copper deposits at multiple stratigraphic positions, from uppermost basement through lower Nguba Group, and, at Dikulushi ~150 km north of the

Copperbelt (Haest et al., 2009), in the Kundelungu Group (Figure 2.1); despite this variation, most deposits display many common elements.

Most deposits are hosted by reduced rocks that overlie oxidized rocks. Reductants in the rocks may be in situ (carbonaceous material, pyrite) or mobile (H2S, CH4, petroleum). Deposits in reduced rocks lacking adjacent oxidized rocks may occur along late structures that could have provided a means for mobile hydrocarbon access (e.g., Kipushi). Although reduced rocks are the most favorable sites for mineralization, the most carbonaceous rocks within an ore horizon are commonly not economically mineralized. Examples of highly carbonaceous rocks in a mineralized area that lack significant copper sulfides include the western carbonaceous facies of the Copperbelt Orebody Member in the Zambian

Copperbelt and the highly carbonaceous sequences of R.S.F. and S.D. unit rocks within blocks of the

Mines Subgroup at Kolwezi, Tenke-Fungurume, and Kisanfu in the Congolese Copperbelt.

Most deposits in the Central African Copperbelt appear to have formed adjacent to early, syn- sedimentary growth faults. Such structural controls are readily apparent in the authochonous deposits of the Zambian Copperbelt and are suggested by ore-associated thickness and facies changes in the allochthonous deposits hosted in the Mines Subgroup of the Congolese Copperbelt. Many of these early faults appear to have been reactivated during Mwashya-lower Nguba extension; their syn-sedimentary nature can be discerned through changes in stratal thickness of Roan Group rocks and by increased folding and deformation that was commonly focused by these structures during Lufilian deformation.

Many of the largest deposits in the district, including Kamoa, Kansanshi, Kolwezi, and Konkola, are spatially associated with abundant mafic sills or flows or aeromagnetic anomalies that may represent 45 buried mafic intrusions (Hitzman, unpub. data, 2010). Although there is no evidence of a direct link between Mwashya-age igneous activity and mineralization, such intrusions may have localized fluid circulation within the basin.

Most deposits in the Central African Copperbelt contain both disseminated and vein- or nodule- controlled sulfides. The majority of deposits are dominated by disseminated sulfides and some, such as the Kamoa deposit, essentially lack veins. In less metamorphosed deposits, disseminated sulfides commonly occur within interstitial sites post-dating other secondary (authigenic) phases, but may also replace detrital grains and cements, including anydrite, carbonate, quartz, and feldspar, as well as diagenetic pyrite. Vein-dominated deposits occur within strongly carbonaceous host rocks which otherwise lack economic mineralization (e.g., Nkana South Orebody [Zambian Copperbelt], Kansanshi, and Sentinel).

Pre-folding veins may consist solely of sulfides or contain other minerals, most commonly quartz and carbonate (dominantly dolomite). Other minerals found in pre-folding veins include K-feldspar, albite, chlorite, sericite, phlogopite, and anhydrite. Vein minerals may be equant or display a fibrous texture; the latter texture is particularly common in the Congolese deposits. Such fibrous veins are texturally transitional with fibrous lenticles and nodules. Sulfide-bearing veins may contain normally metamorphic minerals such as kyanite and phlogopite, even in rocks of low metamorphic grade in the

Congolese Copperbelt (Lefebvre and Patterson, 1982). In most deposits, sulfide-bearing veins are millimeters to 2 cm wide but some deposits, such as Kansanshi, Kipushi, and Dikulushi, contain massive sulfide veins up to several meters in width. Veins and nodules generally contain the same sulfides as those found disseminated in surrounding wallrock, and vein sulfides are commonly coarser grained (up to

3 cm) than disseminated sulfides. Although depletion and enrichment haloes can be found locally around veins, in general terms there is not clear and consistent evidence of either depletion or enrichment

(Broughton, unpub. data, 2011).

Mineral zonation in the deposits of the Central African Copperbelt occurs at a range of scales. At the deposit scale a gross mineral zonation from hematite in oxidized rocks to a chalocite-bornite 46 assemblage in immediately adjacent reduced rocks, especially those adjacent to syn-sedimentary faults, is common. The chalcocite-bornite assemblage changes stratigraphically upward and/or laterally away from syn-sedimentary structures to a bornite-chalcopyrite assemblage, then a chalcopyrite-rich assemblage, a chalcopyrite-pyrite assemblage and finally pyrite. Sphalerite occurs in trace amounts in several of the deposits but is relatively common except on the fringes of the Mufulira and Kamoa deposits; Kipushi is unusual in containing abundant, economically important sphalerite and galena.

Mineral zonation also occurs at a finer level within the deposits between individual beds and may be generally simple where host rocks lack significant compositional layering (e.g., diamictite – Kamoa; sandstone – Chibuluma), to complex and overlapping where layering is well developed (e.g., orebodies of the Mines Subgroup and some Copperbelt Orebody members). Individual sulfide grains may also display sequential replacement textures that mimic the observed broader scale mineral zoning. Where compositional zonation from early to late-formed sulfides is present, such zonation is identical in disseminated sulfides and adjacent veins and nodules (Brummer, 1955; Mendelsohn, 1961a; Richards et al., 1988b; Selley et al., 2005; Sillitoe et al., 2010). The complex mineral zonation observed in some deposits, particularly those of the Mines Subgroup in the Congolese Copperbelt, could indicate either multiple periods of fluid ingress, local host rock variability control on sulfide speciation, or both.

Copper-cobalt sulfides generally form late in any given local paragenetic sequence, during and/or following potassic, magnesian, and silicic alteration which was prevalent throughout the Central African

Copperbelt. These styles of alteration, which include secondary mineral growth of non-replacive diagenetic cements and replacive metasomatic phases, are vertically and laterally extensive, and commonly intense. Alteration was focused within rocks of the Roan Group but affected rocks from the upper basement adjacent to the Katangan unconformity through the Grand Conglomérat and locally into the overlying lower Nguba Group. Although studies are sparse, the upper Nguba and Kundeulungu group rocks do not appear significantly altered, and host no major orebodies. Alteration was regional and appears to not provide any vector toward deposits.

Some alteration types are preferentially developed in certain lithologies. Silicification and dolomitization is dominant in carbonate rocks, whereas potassic alteration is typical in siliciclastic rocks and generally absent in carbonate rocks. Magnesian alteration occurs as Mg-chlorite and tourmaline in siliciclastic rocks and dolomite-magnesite in carbonate rocks.

The alteration sequence can be generalized as an early period of diagenetic dolomite, anhydrite, quartz, and in some cases albite growth, followed by K-feldspar, mainly below the Mwashya Subgroup.

Subsequent Mg-chlorite, talc, Mg-tourmaline, and magnesite growth, and probably ongoing intense silicification, are most prominent in and adjacent to evaporitic carbonate strata of the Mines and Dipeta subgroups of the DRC. All of these alteration types are present within the megabreccia-hosted Mines

Subgroup blocks of the Congolese Copperbelt, and along with the mineralization appear to have formed prior to incorporation of the blocks into the megabreccia. Late sodic alteration is commonly associated with veins and appears to be best developed around the periphery of the main Katangan depocenter; it is prevalent in Mwashya and Nguba group rocks. Structurally controlled late albitic alteration is associated with Cu-(U-Mo-Au-Ni) mineralization and may form discrete haloes to deposits as at Kansanshi,

Frontier, and Lonshi.

The near-surface portions of the deposits throughout the Central African Copperbelt have undergone oxidation and supergene enrichment and such enrichment has been important in upgrading the copper tenor of many deposits. Mineralized zones display a progressive change from primary sulfide

(chalcopyrite-bornite-carrollite) at depth to near-surface mixed oxide-sulfide (chalcocite-copper- carbonate/sulfate-cuprite-native copper) assemblages (Mendelsohn, 1961a). In these zones the location of copper ore may be unrelated to lithological contacts (Fay and Barton, 2012). Malachite and supergene chalcocite are known extend to vertical depths of >1 km at the Konkola deposit (Wilton, pers. comm.,

2010), >600 m in the Nchanga Lower orebody (McKinnon and Smit, 1961), and over 500 m in some of the Congolese écaille deposits (Shuh et al., 2012). Leached caps may reach a thickness of 30 to 60 m

(e.g., Chibuluma, Nkana-Mindola: Mendelsohn, 1961a; Jordaan, 1961). Leached caps are better developed in the siliciclastic hosted deposits of the Zambian Copperbelt than in the carbonate-hosted 48

Congolese deposits. Malachite dominates the oxide zones in many carbonate-hosted deposits whereas chrysocolla is abundant in many siliciclastic-hosted deposits. The oxide portions of many carbonate- hosted Congolese deposits are either Cu-rich or Co-rich. This likely reflects the greater solubility of Cu in supergene fluids (Katsikopoulos et al. 2008; Decrée et al. 2010) and the carbonate nature of the host- rocks.

2.6 Timing of mineralization

The timing of mineralization in the Central African Copperbelt has been debated for over 100 years. In Zambia, early epigenetic-magmatic views (Bateman, 1930; Davidson, 1931; Gray, 1932;

Jackson, 1932) were discounted once it was determined that the Katangan-basement granite contact was unconformable (Garlick and Brummer, 1951). Syngenetic arguments linked ore distribution to sedimentological structures and stratigraphic architecture (Garlick, 1961a, 1964; Binda, 1975; Fleischer et al., 1976) and generally attributed post-depositional features such as metasomatism (Darnley, 1960;

Annels, 1979), deformation, and vein-associated mineralization to post-ore remobilization (Sweeney et al., 1991). Geologists in the Congolese Copperbelt have long noted that mineralization in the écailles predated their folding and disruption (Demesmaeker et al., 1963). Recognition worldwide of the role of diagenetic processes in the formation of sedimentary copper deposits from the 1960s through the 1980s resulted in development of a syn-diagenetic model for the Central African Copperbelt deposits

(Bartholomé et al, 1972; Annels, 1974; Sweeney and Binda, 1989; Cailteux, 1994). This was accompanied by an appreciation of the importance of brines and evaporites (Renfro, 1974; Rose, 1976,

1989; Kirkham, 1989, 2001; Jowett, 1991; Warren, 2000), which influenced genetic and tectonic models

(Unrug, 1988; De Magnée and François, 1988; Cailteux and Kampunzu, 1995; Kampunzu and Cailteux,

1999; Jackson et al., 2003). More recent work has highlighted multistage mineralization spanning the diagenetic to post-orogenic history of basin evolution (Hoy and Ohmoto, 1989; Selley et al., 2005;

DeWaele et al., 2006; Hitzman et al., 2010) and the association of ore with basin inversion-related

49 structures (Molak, 1995; McGowan et al., 2003; Selley et al., 2005; El Desouky et al., 2008; Brems et al.,

2009).

Sulfides in the Central African Copperbelt deposits have complex textural relationships that suggest multistage ore formation (Cailteux et al., 2005b; Selley et al., 2005). Essentially syngenetic framboidal pyrite occurs in both Zambian and Congolese deposits but is not always associated with ore deposits. Diagenetic to late diagenetic copper mineralization is indicated by the typically non-fracture- controlled distribution of both sulfide and gangue phases (e.g., Sweeney and Binda, 1989; Dewaele et al.,

2006), replacive textures of Cu-Co sulfides after diagenetic cements (e.g., Annels, 1989; Hoy, 1989;

Muchez et al, 2008) and framboidal pyrite (Bartholomé et al., 1972; Cailteux et al., 2005a; Schmandt,

2012), and an approximate 816 Ma Re-Os isochron age for chalcopyrite in evaporitic nodules in the hangingwall of the Konkola deposit (Barra et al., 2004). Late diagenetic mineralization is recorded by pre-folding, bedding-parallel sulfide-bearing veinlets, texturally and compositionally comparable disseminated Cu-Co sulfides, and evidence of sulfide precipitation due to interaction between the ore fluids and migrated hydrocarbons (Annels 1979; McGowan et al., 2006; Selley et al., 2005). A Re-Os isochron age on Cu-Co sulfides from two arenite- and one argillite-hosted deposits of the Zambian

Copperbelt at 576 ±41 Ma is consistent with late diagenetic to early orogenic hydrocarbon or sour gas production (Barra et al., 2004).

A post-peak metamorphism albitization event associated with quartz-carbonate veins is in places accompanied by Cu-U-Mo-(Au) mineralization, and occurred at approximately 512 to 500 Ma (Musoshi,

Richards et al., 1988b; Mindola and Kansanshi, Darnley et al., 1961; Torrealday et al., 2000). Concordant

Rb-Sr and Re-Os ages on sphalerite-bornite and bornite-renierite of approximately 451 Ma at Kipushi

(Schneider et al., 2007) and 39Ar-40Ar ages of 490 Ma and approximately 463 Ma, respectively, for biotite and muscovite intergrown with sulfides at Samba (Hitzman, unpub. data, 2006) indicate mineralization continued into the Ordovician. The wide range of sulfur isotopic compositions of sulfides (Dechow and

Jensen, 1965; Hoy, 1989; McGowan et al., 2003; Cailteux et al., 2005a; Lerouge et al., 2005; Selley et al.,

2005; Haest et al., 2009) also indicates a complex, multi-stage history of sulfide precipitation. 50

Recently Sillitoe et al. (2010) utilized vein textures from 14 deposits in the Central African

Copperbelt to argue that virtually all mineralization in the Central African Copperbelt occurred post- lithification of the host rocks, mainly during Lufilian inversion and orogenesis. Their analysis discounted existing geochronological data indicating older mineralization and did not consider the timing of lithification. At least partial lithification of sedimentary rocks, especially carbonates, would be expected within millions, not hundreds of millions of years from the time of deposition (Matthews, 1974). Thus, veins within the Katangan sequence could have been formed due to fluid overpressure during very early during diagenesis. It is clear from textures in the least deformed deposits such as Kamoa, Kamoto and

Konkola that mineralization took place in rocks that possessed some porosity, most probably due to dissolution of both detrital and authigenic mineral phases during a complex diagenetic process. Many of the sulfide-bearing veins throughout the Central African Copperbelt were folded and broken by deformation associated with basin inversion, indicating that these veins pre-dated or at the latest accompanied inversion. Post-metamorphic albite-associated veins and accompanying mineralization clearly post-date the earlier and most economically important stages of mineralization.

The distribution of ore in the Congolese écailles clearly demonstrates that mineralization occurred prior to their incorporation into megabreccias (Demesmaeker et al., 1963; Kampunzu and Cailteux, 1999;

Cailteux et al., 2005a). The ubiquitous positioning of orebodies in reduced rocks at the base of the Roan

Group, despite the presence of favorable host rocks higher in the local stratigraphic section, cannot be reconciled with an entirely late-orogenic age of mineralization that could have mineralized multiple favorable horizons regardless of stratigraphic position. Stratigraphically higher orebodies in Mwashya and

Lower Nguba Group rocks only are known where Lower Roan reduced strata are absent.

The relative amounts of sulfides precipitated during early-, late-, or post-diagenesis of the host sediments in the Central African Copperbelt, as in many other sedimentary copper districts, is poorly constrained (Hitzman et al., 2010). In the Central African Copperbelt, sulfide textures, sulfur isotopic compositions, and geochronology suggest a protracted period of multiple mineralization events. It is

51 probable that copper sulfides in this district were precipitated whenever and wherever oxidized copper- bearing fluids encountered a reductant and a source of sulfur.

2.7 Exploration considerations

Virtually all of the ore deposits in the Central African Copperbelt were located by prospecting for outcropping copper carbonates and oxides, commonly with associated vegetation anomalies due to metal poisoning, or by conventional soil geochemical surveys. In the Congolese Copperbelt, intense silicification of the Kamoto Formation means that these rocks form prominent topographic anomalies, such that most deposits and all major districts were located in the initial years of exploration (cf. Studt et al., 1908). Exploration in Zambia successfully pioneered many techniques, including aerial photography, soil geochemistry, and self-potential (electrical) surveys (Mendelsohn, 1961a). Concealed deposits such as Chibuluma (Fleischer, 1984), Frontier, Kamoa, and Kisanfu have been found by systematic drilling of soil anomalies.

Although geophysics, particularly magnetics, is critical to deciphering stratigraphy and structure, it has proved disappointing in directly delineating deposits. Self-potential anomalies mark most deposits in the Zambian Copperbelt (Mendelsohn, 1961a), but were outlined largely following their discovery.

Electromagnetic methods have proved ineffective due to the absence of major zones of massive to semi- massive sulfide. Induced-polarization methods appear to be limited by the presence of minor carbonaceous material in some horizons and the widespread presence of disseminated iron sulfides.

Gravity surveys may prove useful in delineating structural basins favorable for sites of mineralization but are generally not yet capable of directly detecting orebodies.

Although the intense alteration assemblages characteristic of the Central African Copperbelt

(potassic, magnesian, and sodic) indicate that brine circulation occurred, the alteration assemblages are rarely diagnostic in providing a vector to ore.

Studies in the Zambian Copperbelt, albeit not on a systematic or regional basis, have demonstrated that there may be a shift to lower oxygen and carbon isotopic values in carbonates that have 52 been affected by mineralization relative to unaltered carbonates (Annels, 1989; Sweeney and Binda,

1989; Selley et al., 2005); similar patterns are observed in some deposits of the Congolese Copperbelt (El

Desouky et al., 2010). Although there are a number of potential causes of such isotopic shifts, the most likely is oxidation of in-situ organic material or migrated hydrocarbons during the reduction reactions associated with mineralization (Selley et al., 2005). However, carbon and oxygen isotopic techniques have thus far not been utilized as a routine exploration tool.

Currently, the best exploration technique for the Central African Copperbelt, in association with soil geochemistry and geophysical mapping of stratigraphy and structure, is a thorough understanding of the geology of an area to determine if it contains lithologies capable of serving as a redox trap for oxidized, metal-bearing brines, as well as a fluid pathway and/or trap such as a fault zone, anticlinal closure, or stratigraphic pinchout that could guide and focus mineralizing fluids. Understanding the stratigraphic and chemical architecture of the basin as a whole, as well as a similar understanding of the architecture of local areas, is the key to successful exploration. Exploration for Central African

Copperbelt-type bodies shares many similarities to the search for petroleum. Given this fact, seismic and/or the inversion of potential fields and electrical data to constrain subsurface geology may become common exploration techniques in the coming decades.

CHAPTER 3

DISCOVERY OF THE KAMOA COPPER DEPOSIT, CENTRAL AFRICAN COPPERBELT,

D.R.C.

Sedimentary rock-hosted stratiform copper (SSC) deposits are characterized by laterally continuous, tabular bodies of disseminated mineralization within reduced rocks at or near redox boundaries (Hitzman et al., 2005). The Central African Copperbelt (CACB) of the Democratic Republic of Congo (DRC) and Zambia is the world’s largest SSC province, with a total strike length of approximately 450 km. It encompasses two major ore districts, the Zambian Copperbelt (ZCB) to the southeast and the Congolese (Katangan) Copperbelt (CCB) to the north and northwest. The northwestern limit of the CACB was previously known as the Kolwezi district of DRC, host to numerous major deposits (François, 1973; Cailteux et al, 2005). The recently discovered Kamoa copper deposit is located approximately 25km west of Kolwezi, in an area not previously known to host significant SSC mineralization and distinct from the adjacent CCB (Figure 2.8).

Ivanhoe Nickel and Platinum Ltd (“Ivanhoe”), through its wholly owned subsidiary, African

Minerals (Barbados) Ltd, discovered the Kamoa deposit by systematic application of geochemical and geophysical surveys and drilling. Drilling through February 2009 identified stratiform copper mineralization grading >1% Cu over 3 m in an area covering approximately 81 km2 (Figure 3.1). Within this are two areas totaling 24 km2, where there is sufficient drilling density to determine NI 43-101 compliant inferred resources (Parker, 2009) that are not yet publically available. These two areas are surrounded by an additional 57 km2 of mineralized horizon within which drilling is insufficient to establish an inferred resource. The deposit remains open and a scoping/pre-feasibility study commenced in January 2010.

Figure 3.1: Geology of the Kamoa area, showing location of resource and section 8811900N (Figure 3.4).

3.1 Regional geology

The CACB is hosted in metasedimentary rocks of the Neoproterozoic Katangan Supergroup, within the Pan-African (ca. 580-530 Ma) Lufilian arc, a regional fold-and-thrust belt (Cailteux et al.,

2005a). The Lufilian arc can be divided into five tectonic domains (De Swardt and Drysdall, 1964; Porada and Berhorst, 2000; Key et al., 2001; Selley et al., 2005), with the classical CACB and all major known

Cu-Co deposits located in the Domes region and External fold and thrust belt (Figure 3.1). The Domes 55 region is characterized by inliers or domes of pre-Katangan basement rocks within deformed Katangan

Supergroup cover rocks, and hosts at least three important copper deposits, including Kansanshi

(Broughton et al., 2002), Lumwana, and Kalumbila (Steven and Armstrong, 2003). The External fold and thrust belt is an arcuate domain lying north of the Domes region that encompasses the CCB and the Kafue anticline of the ZCB (De Swardt and Drysdall, 1964). It is characterized by folded Katangan Supergroup rocks that are in autochthonous contact with pre-Katangan basement rocks in the ZCB (Selley et al.,

2005), but which form a series of displaced to allochthonous thrust slices in the CCB (Cailteux et al.,

2005a). All of the classical CACB Cu-Co deposits occur within this domain. The Nzilo basement block west of Kolwezi defines the approximate northwestern limit of the External fold and thrust belt (Figure

3.1). To the southwest in Zambia, Key et al. (2001) defined a relatively undeformed outer domain, the

Western Foreland. In this domain, rocks of the Katangan Supergroup are gently dipping, relatively undeformed, and lie unconformably on pre-Katangan basement rocks. There are no known copper deposits. The Kamoa deposit is located in the northeastern extension of the Western Foreland into the

Katanga province, and is the first major copper deposit discovered within this domain.

There are important tectonic and lithostratigraphic differences between the ZCB and CCB, particularly at the level of ore. In summary, the ZCB contains autochthonous argillite- and arenite-hosted orebodies, stratigraphically positioned <1 km above and locally directly in contact with basement rocks.

The ZCB orebodies are variably folded, but tectonically intact, with strike lengths of as much as 17 km

(Selley et al., 2005). The CCB contains allochthonous dolomitic-rock hosted orebodies disrupted into irregular fragments locally termed “écailles” (Cailteux et al., 2005a). These fragments rarely exceed 1-2 km in strike length, but commonly cluster to form districts such as Kolwezi. The Kolwezi deposits occur with a klippe, an erosional remnant of a high level thrust sheet emplaced within or above the level of K2.1 strata of the Kundelungu Group (François, 1973; Kampunzu and Cailteux, 1999; Jackson et al., 2003).

Due to their disruption and allochthonous nature, the stratigraphic position of the deposits relative to basement is unknown.

Throughout the CACB, the Katangan Supergroup is sub-divided into the Roan, Nguba (formerly

Lower Kundelungu), and Kundelungu (formerly Upper Kundelungu) Groups (Figure 3.2). Both the

Group Subgroup Formation Formation Name Mineralization

Plateaux (K3) K3

Kiubo (K2) K2.1, 2.2 Kundelungu K1.2, 1.3 Kalule (K1) Petit K2.1.1 Conglomerate Monwezi (Ng2) Ng2.1, 2.2 Ng1.3 Ng1.2.2 Kakontwe Nguba Likasi (Ng1) Ng1.2 Grand Ng1.1 Conglomerate Kamoa R 4.20 Mwashya (R4) R 4.10 R3.3, 3.4 Dipeta (R3) R3.2 R3.1. RGS Kambove R2.3 Roan Dolomite (CMN) Dolomitic Shales R2.2 Mines (R2) (SD) Congo Copperbelt R2.1 Kamoto Dolomite orebodies (Kolwezi etc) R.A.T. (R1) R1.3 R.A.T. lilas

Figure 3.2: Simplified stratigraphy of the Congolese Copperbelt, after Cailtreux et al. (2005a).

Nguba and Kundelungu successions commence throughout the CACB with diamictites, respectively the

Grand Conglomerate and Petit Conglomerate. The maximum age of the Katangan Supergroup in the ZCB is constrained by the age of the Nchange granite, dated at 877 Ma (Armstrong et al., 2005). The depositional age of the Grand Conglomerate is constrained in northwestern Zambia to between 765 and

735 Ma (Key et al., 2001).

The Roan Group changes significantly from south to north between Zambia and Congo. In the

ZCB, the Roan Group commences with a basal sequence of coarse hematitic to sulfidic siliciclastic sedimentary rocks, the Lower Roan Subgroup, host to the well-known argillite-hosted Ore Shale and arenite-hosted Mufulira and Nchanga deposits. These rocks are overlain by evaporitic carbonate and lesser siliciclastic sedimentary rocks (Upper Roan Subgroup), and uppermost finer grained siliciclastic and carbonate sedimentary rocks (Mwashya Subgroup). Mafic sills are common in the Upper Roan and

Mwashya Subgroups. The approximate preserved thicknesses of the three subgroups in the ZCB, from bottom to top, are 100 to 1000 m, 30 to 800 m, and as much as 600 m, respectively (Selley et al., 2005).

The Roan sequence represents syn-rift siliciclastic rocks, sag-phase platformal carbonates, and renewed rift-phase siliciclastics and igneous rocks (Selley et al., 2005).

In northwestern Zambia where Key et al. (2001) defined the Western Foreland, the Roan Group comprises Lower Roan Subgroup conglomerate, quartzite, siltstone, and chert, Upper Roan Subgroup ferruginous quartzite, siltstone, and arkosic quartzite, and Mwashya Subgroup mafic volcanic and volcaniclastic rocks. The approximate thicknesses of the three subgroups are, respectively, ≤400 m, at least 800 m, and at least 1000 m. The volcanic rocks are dated at 763 ± 6 Ma (Key et al., 2001).

In the CCB, the Roan Group comprises basal, hematitic siltstones and sandstones (R.A.T.

Subgroup), a thick succession of evaporitic and sulfidic carbonate and lesser siliciclastic sedimentary rocks (Mines Subgroup, host to Cu-Co deposits such as in the Kolwezi district), a mixed siliciclastic- carbonate rock sequence (Dipeta Subgroup), and uppermost finer grained siliciclastic, carbonate, and local mafic rocks (Mwashya Subgroup) (Cailteux, 1994).

The base of the Nguba Group is marked by the Grand Conglomerate, which comprises diamictites with minor interbedded sandstone, siltstone, and conglomerate. It reaches its maximum thickness of approximately 1300 m northwest of Kolwezi and generally thins southward (François, 1973), and is locally <10-m-thick in the ZCB (Binda and van Eden, 1972). The remainder of the Nguba Group comprises dolomitic or sandy shale, siltstone, and carbonate rocks. The base of the Kundelungu Group is similarly defined by a diamictite, the Petit Conglomerate, which is overlain by dolomitic to sandy shale as well as limestone, sandstone, and shale.

Sedimentary rock-hosted stratiform copper deposits in the CACB, as elsewhere, occur at major chemo-stratigraphic redox boundaries between basal red beds (e.g., hematitic Lower Roan and R.A.T.

Subgroups) and reduced host rocks (e.g., Ore Shale and arenite; Mines Subgroup dolomite and dolomitic siltstone). These represent the stratigraphically lowest major redox boundaries within their respective parts of the Katangan basin. The age(s) of mineralization in the CACB remain poorly defined, however, the ZCB and CCB orebodies are affected by Lufilian (Pan-African) deformation and the main phase or phases of mineralization are widely considered to be diagenetic in origin (Bartholomé et al., 1972;

Sweeney et al., 1991; Cailteux et al., 2005a; Selley et al., 2005). In the ZCB, there is an association of

Roan Subgroup orebodies with basin- or sub-basin-bounding growth faults (Selley et al., 2005).

Disruption of the Mines Subgroup orebodies in the CCB makes recognition of any such structures difficult, and orebodies are located along regional anticlines and in thrust sheets where Roan Group rocks are exposed.

In the area of the Kamoa deposit, west of Kolwezi, rocks of the Katangan Supergroup overlie basement rocks of the Nzilo block in a tectonic setting comparable to that in the ZCB and the Western

Foreland, rather than that of the nearby Kolwezi klippe and the External fold and thrust belt (Figure 3.1).

Historical mapping in the vicinity of the Nzilo block indicated that rocks of the Roan Group were limited to relatively thin and discontinuous sandstones, which were assigned to the Mwashya Subgroup

(François, 1973). The sandstones are underlain by a basal conglomerate (locally termed “Poudingue”), and overlain by nearly flat-lying diamictites of the Grand Conglomerate. Much of the broader area 59 surrounding the Nzilo block, where not covered by Kalahari sand, has outcropping or subcropping diamictite. Historically, the Grand Conglomerate was not known to host any significant copper deposits within the CCB.

3.2 Exploration Rationale

The CACB has been a focus of exploration and mining activity since the early part of the 20th century. Almost all of the major orebodies were outcropping or subcropping, and very few major discoveries have been made within rocks of the Lower Roan and Mines Subgroups over the past several decades. However, there has been recent success in discovering or delineating copper deposits at stratigraphically higher positions adjacent to and outside the ZCB (e.g., Frontier and Lonshi deposits east and southeast of the ZCB: Figure 2.4; Kansanshi: Figure 2.8; Broughton et al., 2002).

In the CCB, exploration naturally focused on the part of the Lufilian arc containing rocks of the

Mines Subgroup, an area historically controlled by the DRC state mining company (Gecamines) and its predecessors. Due to political insecurity during the period ~1975 through 2003, exploration and development activities were minimal, and production levels fell precipitously. Recent election of a more stable democratic government and implementation in 2003 of a new mining code encouraged renewed exploration and development, the majority of which has occurred within the External fold and thrust belt and the mapped limits of the Mines Subgroup within the known CCB.

In 2003, Ivanhoe secured 100% ownership of exploration licenses over approximately 20,000 km2 peripheral to the known CCB. In most of these licenses, including those covering the Kamoa deposit, previous mapping and exploration recognized the lack of outcropping mineralization in rocks of the

Mines Subgroup. In addition, large parts of the area west and south of Kolwezi are covered by Tertiary

(Kalahari) sand, presenting a significant impediment to traditional prospecting and geochemical surveying methods. Due to these factors, it is not surprising that these areas received less exploration attention.

Ivanhoe’s exploration rationale was to explore outside of the known, productive part of the CCB, using a variety of geological models for sedimentary rock-hosted copper deposits. Importantly, and in the 60 case of Kamoa, Ivanhoe was willing to develop and explore targets in areas lacking CCB Mines Subgroup strata. Given the proximity to one of the world’s great ore districts, the potential for mineralization within atypical stratigraphic settings or concealed under Kalahari cover was considered excellent.

3.3 Discovery of the Kamoa deposit

Ivanhoe’s work program commenced in January 2004 with the commissioning of a comprehensive independent review of the licenses’ geology, previous exploration history, and prospectivity. At this time, African Mining Consultants were contracted to conduct Ivanhoe’s exploration activities in the region, a position in which they continue to this day. In May 2004, regional stream sediment samples were taken in the license areas immediately west and southwest of Kolwezi. Proximity to the Kolwezi district was the main factor in this decision. Later in 2004, a regional fixed-wing airborne magnetics-radiometrics survey was flown over the Ivanhoe license area, using a line spacing of 250 m.

From late 2004 through 2008, the DRC exploration team consisted of AMC and Ivanhoe staff, a consulting geophysicist, and Douglas Haynes Discovery Ltd (DHD). The team used a systematic ranking approach developed by DHD for identification, prioritization, and ongoing refinement of numerous exploration targets, including Kamoa, within the Ivanhoe licenses.

The potential for copper mineralization in the area of the Kamoa deposit initially was defined in mid-2004 by strongly anomalous stream sediment catchments, with a maximum value of 3679 ppm Cu.

Follow-up soil sampling surveys located copper-in-soil anomalies, with a maximum value of 509 ppm Cu that was broadly coincident with the margins of two magnetic lows within the magnetically responsive

Grand Conglomerate diamictite (Figure 3.3). These lows are now known to correspond to erosional windows into underlying magnetically quiet sandstone of the Mwashya Subgroup, which define the

Kamoa and Makalu domes. Arsenic, bismuth, cobalt, lead, molybdenum, uranium (in radiometrics), and zinc showed positive correlation or spatial association with copper. A reverse-circulation drilling program was initiated in May 2006, targeting anomalies at both the Makalu and Kamoa domes. A total of 2499 m were drilled in 24 holes in the vicinity of the Kamoa dome. The first of these, DKMC_RC159, penetrated 61

Figure 3.3: Contoured copper-in-soil anomalies and second vertical derivative magnetic survey, Kamoa area, showing location of Kamoa and Makalu anomalies, domes, and 2006 RC drill collars. Superimposed are the position of the West Scarp Fault and the upper contact of the Grand Conglomerate (Ng1.1). Note the distinct linear east to northeast-striking magnetic features (possible faults) in the areas north and southeast of Makalu dome.

diamictite and intercalated siltstone of the Grand Conglomerate before terminating in feldspathic sandstone of the Mwashya Subgroup. This, the Kamoa discovery hole, returned 12m @ 1.32% Cu associated with mainly disseminated malachite and native copper in the basal part of the Grand

Conglomerate, and was considered very encouraging.

Following a target evaluation and prioritization workshop in January 2008, the exploration team ranked the Kamoa target highest within the Ivanhoe DRC portfolio. A diamond drilling program commenced in mid-2008 to follow up the 2006 drilling. Drill hole DKMC_DD001 was collared between

RC holes DKMC_RC0175 and RC0177 and corroborated the RC results. Based on the recognition that mineralization occurred at a laterally extensive and apparently stratiform redox boundary, which was the

Figure 3.4: Diamond drill section 8811900N throgh Kamoa deposit west of the Kamoa dome, looking north. Note gently west-dipping strata, stratiform nature of mineralization. Several holes intersected similar mineralization, the best result being 6 m @ 5.01% Cu in DKMC-RC177. Other holes returned poor results, and now are recognized to have collared into the sandstone footwall, intersected leached capping or failed to reach target depth.

contact between gray, sulfidic, reduced diamictite of the Grand Conglomerate and red, hematitic, oxidized footwall sandstone of the Mwashya Group, step-out holes were planned on an east-west section line along a distance ~4.5 km (Figure 3.4). In each of these holes, mineralization again was encountered in the basal diamictite of the Grand Conglomerate. The mineralized zone and strata on this section have an apparent dip of 5-8° to the west.

The lateral extent, lack of tectonic disruption as compared to Mines Subgroup orebodies such as in Kolwezi, and consistent nature of the mineralization were interpreted to represent an intact SSC deposit analogous to the Polish Kupferschiefer and Zambian Ore Shale. This had a critical impact on exploration drill hole spacing, which in the Kupferschiefer and Ore Shale systems is routinely conducted at 1 to 5 km centers, versus <0.5 km in Mines Subgroup orebodies. With increasing confidence, step-out drilling through February 2009 was conducted at 0.8, 1.6, and 3.2 km centers. An independent NI 43-101 compliant technical report with resource estimations was completed in July 2009, and defines inferred resources over an aggregate area of 24 km2 within a larger mineralized, but sparsely drilled area of 81 km2

(Figure 3.1; Parker, 2009), but has not been published.

3.4 Litho-stratigraphy

Six main litho-stratigraphic units are recognized in the vicinity of the Kamoa deposit: Kibaran basement rocks, basal conglomerate (“Poudingue”) of probable Roan Group affinity, hematitic feldspathic sandstones of the Mwashya Subgroup, and diamictite, siltstone-sandstone, and locally intercalated mafic rocks of the Grand Conglomerate.

3.4.1 Kibaran basement rocks

Kibaran rocks crop out extensively within the Nzilo block and were intersected in drill holes.

They consist of quartzite and weakly metamorphosed ferruginous siltstone and sandstone. Mafic rocks also occur within the Kibaran basement; they are folded with the metasedimentary rocks and appear to form sills. Granitic rocks are mapped in the northwestern part of the Nzilo block, and west of Ivanhoe’s licenses.

3.4.2 Roan Group conglomerate and grit (“Poudingue”)

This unit lies unconformably on basement, and comprises as much as 160 m of clast-supported conglomerate with gritty and sandy interbeds. The majority of clasts are Kibaran quartzite, with lesser amounts of other basement lithologies. The age of this unit is not constrained, but similar lithologies are locally interbedded within the overlying sandstones.

3.4.3 Mwashya Subgroup feldspathic sandstone

This unit consists of pink to gray, massive to coarsely bedded feldspathic sandstone with grit and conglomeratic layers, interbedded with lesser maroon fine-grained sandstone and siltstone (Figure 3.5).

Carbonate cement and disseminated carbonate (dolomite) are present. Disseminated specular hematite is common to ubiquitous. Most drill holes terminated in this unit, hence its thickness is poorly constrained, but it has a minimum thickness of ~200 m at Makalu dome, based on two drill holes. Approximately 9 km 64 northwest of section line 8811900N (Figure 3.1), these sandstones are missing and the Grand

Conglomerate is underlain by 175 m of basal conglomerate with minor sandstone, which overlie Kibaran

Figure 3.5: Contact between green-gray reduced basal diamictite of the Grand Conglomerate (upper core box) and underlying pinkish to maroon Mwashya Subgroup sandstone, marks laterally extensive redox boundary and focus for stratiform copper mineralization of the Kamoa deposit. Drill hole DKMC_DD050.

quartzites. Based on comparison with sandstone units overlying the eastern flank of the Nzilo block and underlying the Grand Conglomerate (François, 1973), these rocks are interpreted as belonging to the

Mwashya Subgroup.

3.4.4 Nguba Group diamictite (“Grand Conglomerate”)

This unit crops out throughout most of the project area, and all of the drill holes in the Kamoa deposit collared into the Grand Conglomerate. Approximately 3 km to the northeast of the deposit, the

Grand Conglomerate has a minimum thickness of 800 m as defined by drilling. It consists of muddy to

65 sandy-matrix diamictite with 10 to 30%, millimetric to decimetric clasts (Figure 3.5). The clasts consist mostly of quartzite, with lesser mafic rocks, quartz, schist, and granitoid, and minor argillite and dolomite. In places, the matrix is carbonaceous, and it also contains minor amounts of dolomite. Unlike the underlying feldspathic sandstone, the diamictite contains pyrite or, less commonly, pyrrhotite, rather than hematite. It is the lowermost reduced unit within the Katangan section in the Kamoa area and its basal part hosts copper-rich mineralization.

3.4.5 Nguba Group pyritic siltstone-sandstone

The Grand Conglomerate in the Kamoa area contains multiple interbeds of variably, and locally

>25%, pyritic siltstone-sandstone with minor grit/conglomerate. These are generally well stratified with millimetric to centimetric planar bedding and are as much as several tens of meters in thickness. They can be correlated over distances of several kilometers. The lowermost of these interbeds, the Kamoa pyritic siltstone (KPS), forms the hangingwall to the zone of copper mineralization (Figure 3.4 and Figure 3.6).

Figure 3.6: Pyritic siltstone-sandstone of the Kamoa pyritic siltstone (KPS) that forms the hangingwall to the Kamoa deposit. Note presence of both coarse grained and very fine-grained pyrite. Drill hole DKMC_DD019.

3.4.6 Mafic rocks

To the immediate northeast of the Kamoa deposit, mafic rocks occur near the base of the Grand

Conglomerate, and here the KPS is thin or absent. The mafic rocks include massive basalt, local basaltic hyaloclastite and pillow breccia, gabbroic-dioritic textured rocks, and diabase. Clasts of these mafic lithologies occur in the diamictite. The mafic rocks occur in a slightly higher stratigraphic position than the mafic volcanic rocks of the Mwashya Subgroup in the Western Foreland, which are dated at 763 Ma

(Key et al., 2001). They provisionally are interpreted as correlative with mafic flows and sills that occur within the Nguba and Roan section elsewhere in the Lufilian arc.

3.5 Structure

The Kamoa deposit occurs immediately west of the interpreted boundary between the External fold and thrust belt to the east, and the Western Foreland. In northwestern Zambia, Key et al. (2001) placed the boundary between these tectonic domains at a NE-trending thrust fault marking the northwestern limit of allochthonous rocks of the Katangan Supergroup adjacent and above those of the

Western Foreland. In the area of the Kamoa deposit, a series of three klippen lying east of the Nzilo block, most importantly the Kolwezi klippe, form the westernmost allochthonous units within the

Katangan basin. They all overlie Kundelungu rocks of the K2.1 unit. North of the northernmost klippe and of Tenke, the northern limit of the External fold and thrust belt is defined by the presence of flat-lying sandstones of the Plateaux Subgroup of the Kundelungu Group.

The rocks in the vicinity of the Kamoa deposit are shallow-dipping to sub-horizontal and generally weakly deformed with a heterogeneously developed, generally steeply dipping fracture cleavage or foliation. Rocks of the Grand Conglomerate and Roan Group lack the tectonic disruption that is characteristic of the CCB Mines Subgroup orebodies. In the areas of exposure and in recent drilling surrounding the Nzilo block, the stratigraphic sequence of the Western Foreland lacks the R.A.T. breccias typical of the Roan Group in the CCB, most particularly the Mines Subgroup. This observation led

François (1973, 1993) to conclude that the Roan sequence onlapped against the Nzilo block, which 67 represented a basement high during Roan deposition. Drilling at the Kamoa deposit confirms the absence of Mines Subgroup rocks, as well as the autochthonous nature of the Katangan sequence in this area.

The Katangan Supergroup strata along the eastern edge of the Nzilo block, and east of the Kamoa and Makalu domes, dip gently east to southeast to form the footwall of the three klippen. In the area of the

Kamoa deposit, the interbedded and variably magnetic east-dipping subunits within the Grand

Conglomerate produce a distinctive “striped” magnetic signature (Figure 3.3). Drilling has traced the

Kamoa stratigraphy and mineralization downdip eastwards towards Kolwezi to depths of approximately

700 m, and the full extent of mineralization towards Kolwezi remains unknown.

Many ZCB Cu-Co deposits occur in association with basin- and sub-basin bounding faults that were active during Katangan sedimentation (Selley et al., 2005). Such faults can be recognized by abrupt changes in structural style and by facies and thickness changes within the Katangan section. In the CCB, there are litho-stratigraphic and thickness variations between different parts of the Katangan basin, and even within districts such as Kolwezi (François, 1973; Cailteux, 1994). However, these have not been rigorously linked to early basin structures, nor such structures to mineralization, in part because of the prevailing influence of thrust tectonics. It is thus of interest to determine whether such structures exist in the Kamoa area and, more generally, in the Western Foreland.

Although drilling to date at the Kamoa deposit is relatively widely spaced, it is clear that at least one significant fault exists in the area. The West Scarp fault trends north-northeast across the western part of the deposit area, approximately co-linear with the western edge of the Nzilo block (Figure 3.1 and

Figure 3.3), and forms a prominent west-side-down escarpment. Drill holes west of this feature (~100m west of DKMC-DD008 in Figure 3.4) intersected the base of the Grand Conglomerate at depths 300 to

400 m greater than to the east, indicating that the main part of the Kamoa deposit represents a relative structural high. The stratigraphy at the base of the Grand Conglomerate, and the lithologies in the

Mwashya Subgroup sandstone, are similar on either side of the fault, suggesting it was not an active basin structure at the time of deposition of these units. The up-thrown eastern block containing the Kamoa and

Makalu domes preserves only the lowermost part of the Grand Conglomerate sequence, such that it 68 cannot be determined whether this fault was active during later stages of Grand Conglomerate deposition.

Airborne magnetic survey data define several E- to NE- trending linear magnetic features surrounding the Kamoa and Makalu domes (Figure 3.3). Drilling density is insufficient to determine whether these represent faults, or play a role in the distribution of mineralization.

3.6 Mineralization

Mineralization at the Kamoa deposit consists primarily of disseminated copper sulfides in the basal part of the Grand Conglomerate diamictite. Hypogene ore sulfides consist of disseminated to semi- massive copper sulfides, and generally average between 5 to 10% in abundance. The sulfide minerals occur within diamictite matrix and mantle or partially replace clasts (Figure 3.7 and Figure 3.8), particularly mafic clasts. Sulfides also replace locally interbedded siltstone-sandstones, where they occur preferentially along coarser-grained, more permeable layers and, locally, sandstone dikes (Figure 3.9).

This has been observed in other CACB deposits (Selley et al., 2005), and suggests the sulfide minerals formed prior to lithification of the host rocks. The nature of the sulfides ranges in size from coarse- grained and commonly fibrous, particularly evident surrounding the margins of clasts, to very fine- grained sulfides, more typically found in diamictite matrix and siltstone. Vein-hosted sulfide minerals are uncommon or absent.

Figure 3.7: Chalocopyrite textures, Kamoa deposit. Chalcopyrite mantles and replaces clasts in diamictite, and replaces sandy layers in thin interbed of siltstone-sandstone. Note weak alignment (steeply dipping) of chalcopyrite around clasts. Drill hole DKMC_DD019.

Figure 3.8: Bornite textures, Kamoa deposit. Bornite mantles and replaces clasts in diamictite. Drill hole DKMC_DD019.

Figure 3.9: Sulfide replacement textures, Kamoa deposit. Sandstone dyke cutting siltstones within the basal diamictite, dike is preferentially mineralized with chalcopyrite, suggesting mineralization occurred prior to lithification. Drill hole DKMC_DD053.

Hypogene sulfide minerals generally display a distinct vertical zoning, which from the contact of the footwall sandstone to the contact with the hangingwall pyritic siltstone define a sequence chalcocite- bornite-chalcopyrite-pyrite (Figure 3.10). The total thickness of the hypogene sulfide zone at a 1% Cu cutoff generally ranges from 2 to 15 m. The chalcocite and bornite zones are not always well developed.

Overlap between the individual sulfide zones is common, with Cu-rich sulfides mantling or replacing Cu-

Figure 3.10: Grade distribution, metal and sulfide zonng in hypogene mineralization, Kamoa deposit, drill hole DKMC_DD019.

poor sulfides. In some intersections, sphalerite is present between the chalcopyrite and pyrite zones.

Galena and carrollite are rarely observed, but trace element geochemistry indicates that minor enrichments of Pb, Zn, and Co occur in the mineralized profile, thus defining a classic Cu-Co-Pb-Zn zoning pattern (Figure 3.10). All of these features are typical of SSC deposits and indicate upward movement of ore fluid across the redox boundary. Other SSC deposits in the CACB are typified by weakly pyritic hangingwall rocks, however the hangingwall of the Kamoa deposit contains abundant pyrite, which displays a similar distribution of grain sizes as that of the ore sulfides.

The Kamoa deposit also contains leached and supergene zones, and local oxide mineralization, which define a typical leached capping-supergene-hypogene profile. The leached zone has a vertical thickness of approximately 10 to 50 m, and contains only trace amounts of mineralization, with generally hundreds of ppm Cu. Pyrite in the hangingwall siltstone-sandstone is also leached near surface. 71

Secondary chalcocite, with minor native copper and cuprite, defines a supergene zone that locally extends to as much as 250 m vertical depth, in particular within local fracture zones and along the basal diamictite-sandstone contact, which shows preferential weathering. Grades of >5% Cu are common within supergene zones. Malachite and chrysocolla occur locally, generally after chalcocite, but do not form a significant zone. Two factors appear to have contributed to the development of the leached- supergene-hypogene profile: the strongly pyritic hangingwall and the low carbonate content of the host diamictite.

Copper sulfides may extend a short distance, commonly <1 m, into the footwall sandstone. In most cases, they are minor and consist of chalcocite, chalcopyrite, and/or malachite-chrysocolla, where weathered. To date, no known economically significant hypogene sulfide zones occur in the footwall.

3.8 Significance for SSC exploration and genesis

The Kamoa deposit shares many attributes of SSC deposits elsewhere, including its remarkable lateral extent of mineralized rock. Despite this, and despite its close proximity to the Kolwezi deposits, it remained undiscovered through decades of Copperbelt exploration and development. This provides fundamental encouragement for grassroots exploration both in the CACB and elsewhere, particularly in atypical or “unproductive” geologic settings and tectonic domains situated within or adjacent to major metallogenic belts.

Virtually all of the major SSC deposits in the CACB had a surface expression of outcropping and commonly ore grade copper oxides (e.g., Mendelsohn, 1961a). The classical CACG orebodies are hosted within carbonate or carbonate-rich rocks and have only minor associated hangingwall pyrite, which probably accounts for their lack of leached capping. The strongly pyritic hangingwall and siliciclastic host rocks at Kamoa instead developed a substantial leached capping, and show no surface outcrop expression.

This highlights the potential for discovery of other blind deposits below leached caps, given a similar or analogous chemo-stratigraphic architecture.

The Kamoa deposit shares a common redox architecture with all other major SSC deposits of the

CACB. The deposits, and hence the majority of SSC mineralization, occur at the stratigraphically lowest major redox boundary in any given part of the Katangan basin. In the Western Foreland at Kamoa, this redox boundary is 1-2 km higher in the section than it is in the External fold and thrust belt, because reduced rocks of the Roan Group, such as those of the Mines Subgroup or Zambian-type Ore

Shale/arenite units, are absent adjacent to the Nzilo basement high. This has important implications for exploration and ore genesis.

Exploration for new deposits in underexplored parts of the basin should identify the lowermost major redox boundary, regardless of whether the Ore Shale or Mines Subgroup or, for that matter, Grand

Conglomerate, is present. Onlapping relationships with basement domes may serve, as at Kamoa, to

“migrate” redox boundaries across the strata.

Kamoa and other major CACB SSC deposits not only share a common redox architecture, they also have a common sulfide mineralogy and zoning, and a preferential development of sulfide minerals in coarser grained, more permeable layers. It presently is unknown whether the Katangan basin produced mineralization of similar style at multiple times in the basin history, or via a single basin-wide hydrological event. The location of the Kamoa deposit within the ~750 Ma Grand Conglomerate places important minimum constraints on the timing of SSC mineralization in at least this part of the Katangan basin.

CHAPTER 4 BRECCIAS ALONG THE MARGINS OF THE KATANGAN BASIN IN THE CENTRAL AFRICAN COPPERBELT

The Central African Copperbelt (CACB) of Zambia and the Democratic Republic of Congo

(DRC) contains enigmatic breccias within the Neoproterozoic Katangan Supergroup stratigraphic sequence hosting the copper-(cobalt) deposits of the district. The autochthonous stratiform copper-

(cobalt) deposits of the Zambian Copperbelt (ZCB) lie below stratal disruption associated with breccias, whereas the allochthonous copper-cobalt deposits in the Congolese Copperbelt (CCB) occur as fragments within “megabreccia”. The breccias in the ZCB occur at lithostratigraphic and/or tectonostratigraphic boundaries and in the CCB also form contacts between autochthonous and allochthonous (or para- allochthonous) stratal packages.

The origin of these breccias has been discussed for more than 50 years. The breccias have variously been interpreted as thrust-tectonic (mainly in DRC, e.g. Demesmaeker et al., 1963; François,

1973; Cailteux and Kampunzu 1995), evaporitic or halokinetic (e.g. De Magnee and François, 1988; Bell,

1989; Jackson et al, 2003), sedimentary or olistostromal (Grujenschi, 1978; Wendorff, 2000a, 2000b,

2003; 2005a, b), or extensional-tectonic (Annels, 1984; Selley et al., 2005). Both thrust and extensional models allow a role for evaporites in localizing breccia (e.g. tectonized evaporite models).

This study focuses on breccia from basin-marginal portions of the CACB, namely the ZCB to the southeast and the Kamoa area to the far northwest (Figure 4.1). Breccia generally does not crop out, hence the emphasis is on information from cores from exploration diamond drill holes. These drill cores were logged in detail and samples from the cores were utilized for optical petrology, cathodoluminescence petrology, whole rock geochemical analysis, stable isotopic analysis, and crush-leach analysis of fluids in fluid inclusions. One of the difficulties in critically evaluating models of breccia formation has been the paucity of detailed stratigraphic data regarding their position. Breccia in the ZCB occurs primarily within

74 the well-described lower portion of the stratigraphic section, allowing for a better understanding of the position and stratal association of breccia.

Figure 4.1: Simplified geological map of the Central African Copperbelt showing locations studied or referred to in the text.

Recent work has applied formal sequence stratigraphic analysis to the lower portion of the

Neoproterozoic Katangan Supergroup in the ZCB (Bull et al., 2011; Woodhead, 2013). There are considerable difficulties in applying regional sequence stratigraphic analysis in the absence of seismic and paleontological datasets to sediments deposited in a tectonically active, mixed siliciclastic-carbonate- evaporite basin. The approach taken here begins with traditional “formational” nomenclature defined for the ZCB by Selley et al. (2005) and Hitzman et al. (2012) but utilizes the presence of depositional cycles within the traditional formations and subgroups for correlations. These depositional cycles generally 75 occur at two scales: meters-scale “cycles” and tens of meters- scale “sequences”. Cycles as well as certain individual beds commonly can be traced between exploration drill holes within a given structural block or prospect area over hundreds of meters, and sequences can commonly be traced over kilometers between different prospects and blocks.

4.1 Regional geological setting

The Central African Copperbelt contains rocks of the Neoproterozoic Katangan Supergroup, which has an estimated thickness of 5-10 km in portions of the CCB (Figure 4.2; Batumike et al., 2007;

Bull et al., 2011). These rocks were deposited within a series of linked intracratonic extensional basins or depocenters associated with the breakup of Rhodinia (Unrug, 1988; Kampunzu et al., 1993, 2000; Porada and Berhorst, 2000). The maximum age of the basal Roan Group strata is constrained in Zambia by the unconformably underlying 883±10 Ma Nchanga granite (Armstrong et al., 2005).

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Figure 4.2: Stratigraphic column for the Zambian and Congolese Copperbelts.

Rocks of the Katangan Supergroup occur within a series of extensional depocenters or sub-basins within a broad Katangan basin, located within and on the southern edge of the Congo Craton. This paper will focus on sequences along the margin of the major Katangan basin, namely those in the ZCB to the southeast of the basin and those in the Kamoa area along the northwest margin of the basin. While the stratigraphy of the ZCB has been described in numerous publications, this paper presents the first detailed description of the Upper Roan-Mwashya subgroup sequence in the Kamoa area.

The sedimentary rocks of the Katangan Supergroup are subdivided into three main sequences

(Figure 4.2). The lowermost sequence comprises the Roan Group. This sequence includes initial rift-stage siliciclastic rocks of the Lower Roan Subgroup, post-rift evaporitic carbonate rocks of the uppermost

Lower Roan Subgroup and the Upper Roan Subgroup, and siliciclastic rocks and mafic igneous flows and sills of a second rift stage (Mwashya Subgroup). The second major sequence consists of mixed carbonate and siliciclastic sedimentary rocks of the Nguba Group including at its base a regional marker, the glaciogenic Grand Conglomérat. The Kundelungu Group is the stratigraphically highest sequence. It also commences with a glaciogenic unit, the Petit Conglomérat, and grades upwards into shallow marine to deltaic sedimentary rocks (Selley et al., 2005). These rocks were variably metamorphosed and deformed during the ~590 – 500 Ma Pan-African Lufilian orogeny.

The lower and middle Roan Group in the Zambian Copperbelt has traditionally been subdivided into a syn-rift, predominantly subaerial to shallow marine siliciclastic Lower Roan Subgroup containing most of the ore deposits, and a post-rift, predominantly marine Upper Roan Subgroup containing platformal carbonate rocks, lesser siliciclastic rocks, and the stratiform to discordant breccias described in this paper.

The lower and middle Roan Group in the Congolese Copperbelt (Figure 4.2) comprises a basal unit of variably dolomitic fine-grained siliciclastic rocks, the R.A.T. (Roches Argilo-Talqueuses)

Subgroup, overlain by dolomites and mixed dolomite-siliciclastic rocks of the Mines and Dipeta subgroups of probable marine origin (François, 1973; Cailteux, 1994; Cailteux et al., 2005a; Kampunzu et al., 2005); these rocks are lithostratigraphically equivalent to those of the Upper Roan Subgroup in the 77

ZCB. However, in the DRC these rocks are present only as blocks within megabreccias that are interpreted to result from halokinetic movement (Demesmaeker et al., 1963; De Magnée and François,

1988; Kampunzu and Cailteux, 1999; Jackson et al., 2003).

In both Zambia and the DRC, the Mwashya Subgroup at the top of the Roan Group overlies the uppermost level of breccia and was traditionally viewed as being composed of a lower dolomitic sequence and an upper, normally shale-dominated siliciclastic sequence (Mendelsohn, 1961a; François

1973; Cailteux, 1994). The overlying Nguba and Kundelungu groups are dominated by siliciclastic sedimentary rocks with lesser carbonate rocks. Both successions have basal diamictites termed the Grand and Petite Conglomérat, respectively (François, 1973). Mafic igneous activity occurred in the Central

African Copperbelt between 735-765 Ma, synchronous with the deposition of the Mwashya Subgroup and the basal Nguba Group (Kampunzu et al., 1993, 2000).

Pan-African inversion and deformation of the Katangan succession occurred during the ~590 –

1999; Rainaud et al., 2005). In the Zambian Copperbelt, the Lufilian event resulted in basin inversion with reverse movement and complex folding along and adjacent to earlier formed normal faults

(McGowan et al., 2003, 2006; Selley et al., 2005). Metamorphism and deformation associated with the

Lufilian event are regionally heterogeneous. Katangan rocks of the Zambian Copperbelt generally contain biotite/phlogopite and attained greenschist to lower amphibolite facies (Ramsay and Ridgeway,

1977). The rocks in the Kamoa area along the northwest margin of the Katangan basin are sub- greenschist.

4.2 Breccia Types

Though not the subject of this paper, two main breccia types have historically been distinguished in the CCB: “tectonic breccia”, here termed polylithic clast breccia, and “brecciated R.A.T.”, here termed in situ autolithic breccia. Because the breccias in the CCB are spatially associated with the copper- 78

(cobalt) deposits they have been better described than those in the ZCB. Some of the lithotypes previously described in the CCB (Figure 4.3) are useful for descriptions of the breccias along the margins of the Katangan basin.

Figure 4.3: Reproduced historical “type“ examples of breccia from the Congolese Copperbelt. (a) internal and basal (brêche de charriage, lower image) breccias from Kolwezi district, from François (1973). Basal breccia separates allochthonous Kolwezi klippe from underlying autochthonous strata. Compositional variation is defined by a change of clast type and abundance at left. (b) Brecciated argillaceous siltstone of the upper R.A.T. Subgroup, drill hole at Kamoto deposit, Kolwezi district, from François (1973). Brecciation is defined by bands of dark mineral growth (generally hematite, quartz, chlorite), which produce in situ a mosaic texture outlining incipient “rounded clasts”.

In the ZCB breccias typically occur within the Upper Roan Subgroup, above the stratigraphic position of most copper-(cobalt) deposits. Careful inspection demonstrates multiple breccia lithotypes are present (Figure 4.4). It is possible in some localities to observe a spectrum of lithotypes from non- brecciated to completely brecciated rock.

Figure 4.4: Breccia types and textures. (a) progressive development of crackle breccia in bedded siltstone by veinlets (top) and flooding with partial replacement (bottom) of orange-weathering dolomite- (albite).Konkola area, hole KN3, 95.3 and 97.6m. (b) monolithic clast breccia of green siltstone clasts in white dolomite-magnesite-albite matrix, Itawa hole IT26, ~2505’. (c) in situ autolithic breccia developed in non-bedded talcose siltstone (left) in gradational contact with underlying polylithic clast breccia (right). Matrix is red-weathering ferroan dolomite-albite-(quartz). Note in situ development of round “clasts” which become progressively isolated with increased abundance of matrix: “rounding” is not caused by transport. Konkola area drill hole KW24D1, 98.3m, stratigraphic top to left. (d) two polylithic clast breccia layers (with different clast compositions) above and below an in situ autolithic breccia developed in non-bedded pale siltstone. Incipient “round clasts” in the autolithic breccia are identical to large clast in underlying breccia (arrows). Occasional angular clasts are present. Also, upper left core (double arrow) shows alteration to pale albite-dolomite. Luansobe hole L80, ~2305’. (e) polylithic clast breccia with clast of evaporitic dolomite-anhydrite rock. Note contrast between clast and matrix, distinct differences in breccia matrix and clast composition above and below the clast, and crackle/vein breccia of anhydrite- dolomite veins in overlying bedded siltstone. Luansobe hole L80, 2874’. (f) polylithic clast breccia with brown-weathering dolomitic matrix, nearly clast-supported, note well-rounded sandstone clast, lack of cataclasis, and altered (hematite, quartz-albite-dolomite-phlogopite) clast rims. Luansobe drill hole L62, ~1900’. (g) multiple beds of highly micaceous (phlogopitic) polylithic clast breccia, lower bed contains ~5% clasts. Note in situ autolithic breccia - also with micaceous matrix - in center, L80, ~2400’. (h) polylithic clast breccia with ferruginous albite-dolomite matrix in gradational contact with underlying feldspathic sandstone, localized within intact Upper Roan Subgroup, below breccia complex, Konkola area drill hole KW24(D2), 358m. (i) collapse breccia, drill hole RCB2, 144m, Chambishi basin. All drill cores in (a) – (h) are 5 cm in width.

a. b.

e. f.

Figure 4.4: continued. 81 g. i.

Figure 4.4: continued.

4.2.1 Crackle/vein breccia

Crackle/vein breccia consists of a network of partially to completely interconnected veins cutting country rock, dominantly siltstone or carbonate-bearing siltstone. The veins commonly form 5% to 25% of the rock by volume (Figure 4.4a). In bedded rocks these veins commonly are oriented both parallel and at a high angle to bedding, though they may display highly irregular orientations. The veins are simple, narrow (≤1cm), single-opening structures without central fractures. Contacts between the vein and wallrock may be diffuse rather than sharp. Where veins are wider or more abundant, wallrock fragments

(lithons) between veins may have undergone reorientation and/or local movement (Figure 4.4a).

4.2.2 Monolithic clast breccia

Monolithic breccia consists of disrupted and reoriented siltstone, carbonate-bearing siltstone, or sandstone clasts of a single lithotype set in a matrix of coarse-grained carbonate-anhydrite-albite-(talc)

(Figure 4.4b). Clasts are commonly irregular in shape, and clast margins may be partly replaced by matrix minerals. This breccia type forms discrete conformable layers alternating with layers of massive carbonate-anhydrite-albite and is interpreted as monomict intraformational breccia.

4.2.3 In situ autolithic breccia

In situ autolithic breccia occurs in massive-bedded siltstone, carbonate-bearing siltstone, or fine- grained sandstone. It consists of isolated to adjoining, centimeter-sized lithons of siltstone or sandstone separated by seams/bands of carbonate-anhydrite-albite-hematite-mica-talc (Figure 4.4c, d). The seams/bands are generally curvilinear, resulting in an in situ mosaic of angular to rounded lithons.

Gradual isolation of the lithons by increased abundance of the intervening matrix produced dominantly rounded clasts in a matrix-supported breccia (Figure 4.4c). Detailed examination of such breccia demonstrates that clast rounding occurred in situ by progressive mineral growth and alteration of incipient clast rims during diagenesis. This interpretation is at variance with previous interpretations of rounding by tectonic or sedimentary processes (Cailteux and Kampunzu, 1995; Wendorff, 2000a).

4.2.4 Polylithic clast breccia

Polylithic clast breccia is the most common breccia type in the ZCB. It is megascopically similar to “tectonic breccia” in DRC (e.g. François, 1973; Cailteux et al., 1994; Figure 4.3a). It is generally matrix supported and is comprised of round to subangular clasts or fragments in a matrix comprised variably of dolomite/magnesite, albite, quartz, anhydrite, chlorite, biotite-phlogopite, talc, and hematite

(Figure 4.4c, e-h). Polylithic clast breccia commonly lies within or above a zone of intense, often texturally destructive albitic or dolomitic alteration, which may extend tens of meters into the footwall.

Clast abundance varies from <5% to 50%. Clasts range in size from sub-millimeter to meters to beyond the limit of resolution in drill core, where it is difficult to determine whether blocks between breccia zones are beds or large clasts (Figure 4.4c, e, f).

Clast types are dominated by poorly bedded siltstone, dolomitic siltstone, sandstone, and less commonly, dolomite. Clasts of evaporitic nodular or bedded dolomite-anhydrite rock similar to rocks immediately below the breccias may be present (Figure 4.4e) but are uncommon. Clasts invariably appear to have been derived from adjacent strata within the local evaporitic section (i.e. the Upper Roan

Subgroup). Clasts from both above and below the stratigraphic position of the breccia appear to be 83 present, though the polylithic clast breccia generally contains fewer clasts from the footwall of the breccias than the hangingwall.

Clasts of autolithic and crackle breccia occur within polylithic clast breccia. Basement clasts are not present, nor are clasts of Lower Roan Subgroup sandstone or conglomerate. Both oxidized (reddish, hematitic) and reduced (grey/green, pyritic) clasts can co-occur. However polylithic clast breccia in most of the localities studied is hematitic.

Clast shapes range from round to subangular and breccias may commonly contain admixed rounded to subangular clasts (Figure 4.4c). Rounding of the clasts is suspected to be due to similar in situ diagenetic processes to those observed in the autolithic breccia, with which it commonly is gradational

(Figure 4.4b, c). Clasts in clast-rich polylithic breccia do not display evidence of cataclasis as would be expected in a fault breccia (Figure 4.4f). Clasts typically are isolated and suspended in the matrix, even where sand-sized, rather than being clumped or “welded” together. Polylithic clast breccia is not overprinted by younger brecciation.

The matrix of polylithic clast breccia is comprised of various proportions of carbonate, albite, anhydrite, quartz, chlorite, phlogopite, hematite, and accessory phases (Figure 4.5a, b). The matrix mineralogy of the polylithic clast breccias is typically the same as those in adjacent autolithic and crackle breccia. In most examples, matrix mineralogy of polylithic clast breccias is dominated by dolomite/magnesite and albite, but in some instances matrix may be dominantly micaceous (Figure 4.4g).

Although co-occurring in matrix, dolomite and albite commonly show distinct timing relations. Intricately growth-zoned dolomite most commonly engulfs earlier formed tabular, often untwinned albite (Figure

4.5). The albite may also display growth zones, and in some instances overgrows rounded blocky grains of probable detrital feldspar (Figure 4.5c, d). Detrital quartz grains may be present (Figure 4.5e, f). Rarely albite shapes suggest pseudomorphing of swallow-tail gypsum (Figure 4.5g, h); there is no textural evidence for pseudomorphed halite. The margins of clasts in dolomite-albite matrix polylithic clast breccia are commonly altered to dolomite, quartz, chlorite, phlogopite, and/or hematite (Figure 4.4f).

a. b.

c. d.

e. f.

g. h.

Figure 4.5: (a-d, g-h) Paired photomicrographs of polylithic clast breccia in cross-polarized light (left) and cathodoluminesence (right), drill hole DH219, Mufulira mine, 1747.8m. (a, b) albite-dolomite breccia overprinting micritic (sedimentary) dolomite, composed of pink-orange luminescent dolomite mosaic, overprinted by wispy network of pale tan-luminescent dolomite forms latest growth stage of zoned euhedral red to tan-luminescent dolomite of breccia. Zoned dolomite overgrows earlier tabular dark/red- luminescent albite; (c, d) tabular albite overgrowth on detrital grain (K-feldspar?) with dust rims. (e, f) detrital quartz grains in matrix of polylithic breccia from breccia complex, with argillaceous clast; hole L80, Luansobe prospect, 2788’. (g, h) early-formed tabular albite grain with possible “swallow-tail” morphology, cut by younger zoned dolomite.

Micaceous matrix breccia has abundant phlogopite and/or chlorite, which in some examples comprises >60% of the rock (Figure 4.4g). This matrix is texturally different from that of argillaceous rocks in the Upper Roan Subgroup, lacking evaporitic nodules/casts and sandstone lenses. Micaceous breccia may be partially replaced by dolomite, quartz or albite (Figure 4.4c).

Polylithic clast breccia occurs both as isolated thin (meters-scale) individual breccia units and as thick (tens of meters) multiple units separated by other breccia types and/or unbrecciated rock. Intervals containing polylithic clast breccia interleaved with other breccia types and lenses or beds of unbrecciated rock are here termed breccia complexes. The individual breccia layers or lenses and their interleaved rocks are difficult to correlate between drill holes. These complexes may pass laterally into sequences with a single thin breccia unit. Individual breccia bodies and breccia complexes may thin and thicken abruptly.

Individual polylithic clast breccia units commonly lack internal structure and are unsorted and ungraded without internal bedding. However, compositional variation occurs within breccia complexes

(Figure 4.4c, e, g) where it defines layering characterized by differences in clast size, morphology and lithology. Layers may have distinct contacts, but commonly are separated by an intervening zone of in situ autolithic or crackle brecciated rock. These features are interpreted as preserved bedding.

Contacts between polylithic clast breccia and underlying and overlying rocks generally appear conformable (e.g. Figure 4.4h). However, contact relationships are often difficult to evaluate due to the massive-bedded character both of the breccias and of adjacent sedimentary rocks. Contacts with adjacent breccia types are usually gradational.

The distribution of polylithic clast breccia relative to crackle/vein breccia is systematic. Where only a single polylithic breccia is present, crackle/vein breccia is asymmetrically developed over meters to tens of meters in its footwall but typically is absent from the hangingwall. Within a breccia complex, crackle/vein breccia usually occurs between each unit of polylithic clast breccia but is absent above the complex.

In situ autolithic breccia is commonly developed in massive-bedded siltstones and fine-grained sandstones within breccia complexes. It tends to be absent in the footwall of breccia complexes, possibly because these rocks are often carbonate or carbonate-anhydrite rocks within which autolithic breccia is not developed. Autolithic breccia also is absent where polylithic breccia is overlain by carbonate rocks.

Breccia bodies or layers are regionally folded along with their enclosing rock sequences and the breccia may display foliation where the surrounding rocks are foliated. However, most polylithic clast breccia is non-foliated or only weakly foliated. The polylithic clast breccia lacks evidence of clast deformation, imbrication, or cataclasis (Figure 4.4). Meters-thick strongly schistose intervals and transposed bedding occur above breccia units, but are uncommon or absent along their footwalls. Overlying schistose zones usually contain lenticular-boudinaged siltstone and talc-carbonate rock probably derived from thinly interbedded siltstone and talc-carbonate rock sequences. Schistose zones beneath breccia units, where present, are commonly located beneath thin intervals of apparently intact sedimentary rocks. Where the breccia and its hangingwall rocks are albitized, highly foliated textures occur in rocks above the albitized zone.

4.2.5 Mafic-associated breccia

Polylithic clast breccia containing clasts of mafic igneous (gabbroic to dioritic) in addition to sedimentary rock clasts occurs in the western ZCB, particularly the Chambishi basin. These breccias are spatially associated with podiform mafic bodies within the Upper Roan or lower Mwashya subgroups

(Annels, 1984; Binda and Porada, 1995). Mafic rocks also occur in the Kamoa deposit area within the basal Grand Conglomerate unit (Broughton and Rogers, 2010), and include flow top breccias and hyaloclastite with textures indicative of emplacement into sediment.

Mafic-associated breccias may have a carbonate-albite matrix but more commonly have a micaceous matrix. The mafic rocks clasts typically lack chilled margins or metamorphic haloes, and hence have been viewed as exotic “clasts” within megabreccia. In many mafic-associated breccias the mafic igneous clasts have been converted into fine- to coarse-grained aggregates of albite, scapolite, 87 hornblende, and/or actinolite. These breccias probably formed by similar processes to the polylithic clast breccias but are not described further in this paper.

4.2.6 Angular collapse breccia

Breccias consisting of close-packed polylithic angular clasts indicative of formation via collapse

(Figure 4.4i) are known from the western ZCB in proximity to mafic-associated breccia (Woodhead,

2013), but with the exception of the Chambishi basin area are absent from the localities studied.

4.3 Breccias in relation to evaporitic depositional cycles

Breccias form part of a systematic architecture of evaporitic depositional cycles and sequences.

These are recognized not only in the Upper Roan Subgroup but also in other evaporitic parts of the Roan

Group, most commonly the Kitwe Formation. The baseline depositional unit is a shallowing-upwards cycle, which commonly ranges in thickness from approximately 0.5m to <5m (Figure 4.6a, b). In generalized form cycles begin sharply with a massive-bedded siltstone or sandstone that lacks evidence of wave action. These siltstones and sandstones are often dark colored due to the abundance of secondary phlogopite. This lower interval rarely if ever contains evaporitic textures and formed in a sub-tidal or sub- wave base environment. It is overlain by lenticular and/or ripple-bedded siltstone and sandstone, or siltstone and dolomitic sandstone/sandy dolomite, indicative of intertidal or above-wave base conditions.

Evaporitic textures are minor or absent. The overlying interval comprises carbonate rock composed of either dolomite or magnesite or both. The carbonate rock may be massive-bedded or display laminated

(algal) and/or vuggy textures. These carbonate rocks are locally nodular with the nodules consisting of purple crystalline anhydrite or cream-white fine-grained magnesite and/or dolomite. Both carbonate rock and nodules commonly have a slightly ferroan composition, readily recognized in weathered drill core.

The upper part of the cycle consists of highly nodular carbonate (dolomite and/or magnesite)-anhydrite rock that may include cm-interbedded anhydrite and carbonate layers. This upper interval may develop an in situ incipient breccia texture (Figure 4.6c) comparable to that of in situ autolithic breccia in massive 88

a. d.

Figure 4.6: Shallowing-upwards evaporitic cycles in the Zambian Copperbelt. (a) Oblique up-sectional view of the Rokana Evaporites Member of the lower Kitwe Formation, showing ~meter-scale depositional cycles characterized by poorly bedded siltstone and fine-grained sandstone grading up to brown-weathering ferroan dolostone, locally with evaporitic textures. Mindola pit, Nkana mine, Chambishi basin area, daypack for scale. (b) Evaporitic cycle in the Antelope Clastics Member of the uppermost Kitwe Formation, showing dark phlogopitic massive siltstone (far right) overlain by lenticular bedded siltstone and pale dolomitic sandstone (right center), ~massive-bedded cream-white magnesite/dolomite with minor anhydrite (left center), and interbedded magnesite/dolomite and purple anhydrite with locally isolated “clasts” of carbonate marking the top of the cycle. The sharp base of the overlying cycle is visible at far left. A brownish tint to the weathered carbonates indicates a slightly ferroan composition. Drill hole RCB2, ~982m, core width ~5cm. (c) Detail of evaporitic textures in the upper parts of cycles, showing in situ development of subrounded to subangular clasts of carbonate by growth of matrix anhydrite. Compare with Figures 3b and 4. Drill hole RCB2, ~942m, core width ~5cm. (d) Upper bedding surface of evaporitic cycle in (a), with polygonal dolomite crusts indicative of subaerial exposure, hammer for scale. As is typical in other localities, the other cycles in this exposure lack such features and were not subaerially exposed. siltstone (Figure 4.3b and Figure 4.5). The top of the cycle is usually marked by a sharp contact and a return to non-evaporitic lithologies. Erosional contacts and truncated enterolithic bedding are rare or 89 absent, indicating that the uppermost evaporitic part of the cycle generally was not subaerially exposed. In a continuous exposure of the Rokana Evaporites Member in the Mindola pit (Nkana deposit in Chambishi basin, Figure 4.1), only one of more than a dozen cycles was capped by polygonal dolostone crusts indicative of exposure (Figure 4.6d). The meter-scale thickness, lack of anoxic planar-bedded strata, and repetitive, autocyclic nature of these cycles suggests that water depths remained relatively shallow during their deposition.

Numerous variations on this idealized cycle occur. In general these consist of partial cycles where only one or more of the lithotypes are present within a localized sequence of cycles where all lithotypes commonly are present, and cycles where the environment of deposition is shifted to siliclastic-dominated

(carbonate and evaporitic components are minor) or to carbonate-evaporite dominated (siliclastic components are minor). In some instances cycles may display a gradational rather than sharp base/top.

Individual lithotypes also may form alternating beds rather than gradational cycles. Many of these variations can occur within a given sequence.

Sequences are composed of these cycles or partial cycles and are usually several tens of meters in thickness. Evaporitic sequences in the Upper Roan Subgroup gradually become more carbonate-evaporite dominant up-section (i.e. a brining-upwards sequence). Sequences are overlain by multiple cycles recording a return to non- or less-evaporitic conditions, marking the base of the next sequence, or by polylithic breccia or a breccia complex.

4.4 Stratigraphic position of breccias and lateral variations in breccia types

Exploration drill holes at five localities in the ZCB, two on the west side and three on the east side of the Kafue anticline and one at Kamoa (Figure 4.1), allow the breccias to be placed in a stratigraphic and tectonic context.

4.4.1 Northern portion of the Zambian Copperbelt - Konkola area

The Konkola area lies at the northwestern end of the ZCB (Figure 4.1). In this area the Upper

Roan Subgroup, which is placed at the base of the first dolomite bed, has a transitional boundary with underlying rocks of the Antelope Clastics Member (“Shale with Grit”) of the Lower Roan Subgroup. The upper boundary of the Upper Roan Subgroup usually is defined by polylithic clast breccia that marks a transition to overlying rocks of the Mwashya Subgroup.

The Konkola mine is situated within the Kiralabombwe anticline between the Fitwaola and

Lubengele faults, which divide the area into three structural blocks (Figure 4.7). In the Konkola mine

Figure 4.7: Generalized geology of the Konkola area, showing location of drill holes described in text. Modified from Hitzman et al., (2012).

91 block and to its south in the Kakosa block the basal portion of the Lower Roan Subgroup, the Mindola

Clastics Formation, is exceptionally thick (>800m), whereas north of the Lubengele Fault in the Kawiri block it is only tens of meters in thickness (Hitzman et al., 2012). These faults are interpreted as growth faults active at various stages during deposition of the Roan Group (Selley et al., 2005, Hitzman et al.,

2012).

The Upper Roan Subgroup in the Konkola mine block comprises three ~50m thick sequences,

UR1 through UR3 (Figure 4.8). The tops of the lower two sequences are marked by units of distinctive albitized and locally cross-bedded sandstone. The top of the third sequence is marked by a thin unit of albitized planar-bedded siltstone followed abruptly by polylithic clast breccia. The breccia is overlain by non-evaporitic siltstones, shales and sandstones of the Mwashya Subgroup.

These three sequences can be traced through the Kawiri block. Here a breccia complex is present instead of a single breccia unit (Figure 4.8). The lowest level of breccia occurs in different drill cores at slightly different stratigraphic levels within the third sequence, and incipient breccia textures occur in rocks laterally equivalent to breccia (Figure 4.8). Depositional cycles within the Upper Roan Subgroup can be correlated between these incipient breccia units. These observations indicate a sedimentary rather than tectonic origin for the breccia and incipient breccia.

Gabbroic rocks occur in several drill holes in the Konkola area, particularly in the Kawiri block

(Figure 4.8). In some instances (e.g. drill hole KN18) the gabbros occur above the level of breccia within siltstones of the Mwashya Subgroup, and are associated with albite alteration but not breccia. In other drill holes gabbroic rocks occur lower in the stratigraphy within the breccia complex.

In the Konkola mine and Kawiri blocks, the Upper Roan Subgroup comprises a mixed clastic- carbonate sequence including massive siltstone and sandstone beds, dolostone beds, and meters-scale shallowing-upwards cycles (Figure 4.8). Nodules of fine-grained white dolomite or magnesite are common and are comparable to “chicken wire” texture in evaporitic dolomite (Warren, 2006). Stylolites truncate the nodules (Figure 4.9a).

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Figure 4.8: South – north drill section for the Upper Roan Subgroup across three major structural blocks in the Konkola mine area, with the base of the Antelope Clastics Member of the uppermost Lower Roan Subgroup as datum. Hole KLB145 is representative of the mine area (Konkola mine block) and contains three mixed siliciclastic-carbonate-evaporite sequences (UR1-3) below a thin breccia marking the contact with the Mwashya Subgroup. In the mine area the Lower Roan Subgroup is anomalously thick (>800m, not shown). South of the Fitwaola fault within the Kakosa block hole KLB94 these sequences largely are missing, and direct correlation is not possible. This indicates a different structural depocenter. North of the mine area across the Lubengele fault (Kawiri block) the Lower Roan Subgroup is <100m thick, suggesting this area lies in the footwall of the fault. However the three Upper Roan sequences can be traced from the mine area, suggesting the fault was inactive. The sequences are overlain by a thick breccia complex (UR4) unlike that in the mine area, and mafics (and associated breccia) are common in the Mwashya Subgroup. Breccia in the mine block occurs at the top of sequence UR3. In the Kawiri block the base of breccia occurs at variable positions, and incipient breccia correlate laterally with breccia.

Figure 4.9: Evaporitic and incipient breccia textures in Upper Roan Subgroup, Konkola area. (a) white dolomite/magnesite nodules at top of bed, truncated by stylolite marking contact with overlying dolostone. Hole KN18, 1145.9m. (b) thin-bedded silty dolomite with vuggy evaporitic lenticules and nodules of dolomite-quartz containing chalcopyrite dated at 825 ± 65Ma, KN18, 1227.6m. (c) coarse white dolomite-quartz forms irregular veins invading siltstone (top image); medium-grained dolomite- quartz replaces beds and forms interconnecting veins between beds (lower image) KN18, 1138.6, 1140.3m. (d) grey dolomite with dark laminae defined by bedding-orthogonal quartz grains, and with replacive nodules and patches of white dolomite + grey quartz, locally with similar bedding-orthogonal quartz grains lining the nodule. KN18, 1171.3m (e) white dolomite-quartz partially replacing and brecciating beds of laminated dolomite-siltstone and massive textured tan siltstone, KN18, 1190.8m. (f) interbedded red ferruginous dolomite-albite rock and grey siltstone, with incipient brecciation and stoping/dissolution (arrow) of siltstone, KLB99, 1220’. (g) in situ brecciation of laminated siltstone beds by ferruginous dolomite-albite rock, KW24, 137.1m. (h) incipient brecciation of siltstone beds by partially mobilized ferruginous dolomite-albite beds, with soft-sediment folding and preservation of general bedding orientation, KW24, ~150m. (i, j) photomicrographs in crossed-polarized light and cathodoluminesence of ferruginous dolomite –albite bed showing intergrowth of blue luminescent albite and growth-zoned dolomite. Earlier possibly detrital feldspar grains are locally visible (arrow). Konkola area, drill hole KNG6, 216.2m. (k) photomicrograph of ferruginous dolomite-albite bed with quartz overgrowth preserving dust rim on rounded detrital grain, dolomite also overgrows dust rims on detrital grain, cross-polarized light, Konkola area, hole KW24, 335.3m. (l) recumbent folds in thinly bedded siltstone and ferruginous albite-dolomite rock, note mobilization of dolomite out of fold closures, lack of penetrative cleavage, and partial replacement of siltstone. KN18, 1325.9m. (m) intraformational rootless recumbent folds within dolomite beds, KN3, 369.9 m.

a. b.

d. e.

f. g.

Figure 4.9: continued.

95 h.

i. j.

Figure 4.9: continued. 96

Dolostone beds contain vuggy bedding-parallel lenticles and isolated nodules of coarse-grained locally fibrous grey-white dolomite and quartz (Figure 4.9b). Pyrite and chalcopyrite are commonly associated with these lenticles and nodules, and a Re-Os date of 825 ± 65 Ma on chalcopyrite from this rock type confirms a diagenetic age (Barra et al, 2004). Dolomite-quartz patches and veins invade siltstone (Figure 4.9c, upper image), form beds (Figure 4.9c, lower image) and lenticular nodules (Figure

4.9d), and replace beds locally to form breccia (Figure 4.9c, lower image; Figure 4.9e). Patches of dolomite-quartz truncate and replace earlier dark-colored laminations defined by quartz in growth alignment perpendicular to bedding planes (Figure 4.9d). These textures are characteristic of shallow water evaporitic settings below the sediment-brine interface; such textures can be formed either as a primary precipitate or as a replacement of earlier sulfate (Warren, 2006). Unlike many areas of the ZCB, anhydrite is relatively uncommon in rocks of the Roan Group rocks in the Konkola area.

The Upper Roan Subgroup and less commonly the Antelope Clastics Member also contain beds of red ferruginous albite-dolomite rock (Figure 4.9f-k). This rock has textural similarities to in situ autolithic and polylithic clast breccia and in places displays an incipient breccia texture. The similarities include local dissolution and albitic alteration of both overlying and underlying siltstone beds (Figure

4.9f), intraformational brecciation of siltstone beds (Figure 4.9g), and disaggregation to partial mobilization of siltstone beds (Figure 4.9h). Petrographically, coarse growth-zoned dolomite is intergrown with or post-dates authigenic non-pseudomorphic albite (Figure 4.9i, j). Sedimentary textures are not usually preserved, but include local quartz, albite and dolomite overgrowths on rounded detrital grains, locally preserving dust rims (Figure 4.9i-k). Compositional layering of albite and dolomite also may be present (Figure 4.9i, j). These features are indicative of replacement and incipient brecciation of pre-existing beds. The dolomite-albite beds are thought to represent former evaporite layers. Incipient breccia and ferruginous dolomite-albite beds are rare or absent above the level of polylithic clast breccia.

Where the dolomite-albite beds are developed in a sequence of thinly interbedded siltstones they locally display mesoscopic recumbent folds (Figure 4.9m). The folds are intraformational, locally refolded, and in places are rootless. During folding, dolomite (or its precursor) was apparently evacuated 97 from fold closures so that siltstone beds were folded upon themselves. The folded siltstone beds lack an axial cleavage, which suggests that folding occurred prior to lithification.

Throughout most of the Konkola mine and Kawiri blocks, polylithic breccia at the top of sequence UR3 is overlain by non-evaporitic siliciclastic rocks of the Mwashya Subgroup. Near the boundary with the Kakosa block, polylithic breccia at the top of sequence UR3 is overlain by thickly bedded vuggy white to pink dolostone and minor interbedded siltstone rather than by typical siltstone and shale of the Mwashya Subgroup. This distinctive package of rocks is limited to southwest of a northwest- trending line subparallel to the projected trace of the Fitwaola fault (Figure 4.7 and Figure 4.8). These dolostones have been assigned by various workers either to the Upper Roan Subgroup (e.g. Mendelsohn,

1961a) or to a lower portion of the Mwashya Subgroup (c.f. Selley et al., 2005). They are similar to those of the Kansuki Formation in DRC now assigned to the upper part of the Upper Roan Subgroup (Cailteux et al., 2007). To the south of the Fitwaola Fault the Antelope Clastics Member is also anomalously thick and is directly overlain by dolomitic matrix polylithic clast breccia, such that the three sequences seen north of the fault are absent. The breccia is overlain by dolostones of the Kansuki Formation; the deeper water siltstones and shales typical of the Mwashya Subgroup north of the fault also are absent.

This “cutout” of the Upper Roan sequences and absence of typical Mwashya Subgroup siltstone- shale facies to the southwest of the Fitwaola fault is thought to represent a lateral facies change. However, stratigraphic relations above the breccia are unclear, as both the siltstone-shale units of the Mwashya

Subgroup and the dolostones of the Kansuki Formation are deformed throughout the Konkola area, with steeply dipping beds, recumbent folding, transposition, and foliation boudinage. Mesoscopic recumbent folds also are present in rocks of the Upper Roan and locally Lower Roan subgroups below the level of breccia, but structural repetition of stratal packages is absent. This suggests the presence of a décollement at or near the level of breccia. In drill core, a strongly schistose, talcose and folded interval is present above undeformed breccia in many drill holes, in places above a strongly albitized zone adjacent to the breccia. This deformed interval is interpreted to mark a zone of structural decoupling. The amount of translation is unclear but probably local in scale. 98

The predominance of dolomite and the lack of deep water sediments above the Antelope Clastics

Member suggests the Kakosa block occupied a footwall position relative to the block north of the

Fitwaola fault. A major facies change at the level of the Upper Roan and Mwashya subgroups occurred across the Fitwaola fault. Lufilian inversion of the Fitwaola fault was probably responsible for deformation that was focused within the Mwashya Subgroup and Kansuki Formations.

4.4.2 Eastern portion of the Zambian Copperbelt

The stratigraphic sequence along the eastern side of the ZCB is known from drill holes in the

Luansobe, Mufulira, and Itawa areas (Figure 4.1). Above the Mindola Clastics Formation the Lower and

Upper Roan subgroups contain up to nine depositional sequences below a breccia complex (Figure 4.10).

The lowest five sequences occur in the Lower Roan Subgroup and are each ~20 to ~50m in thickness.

Each sequence is capped by a prominent unit of massive to cross-bedded feldspathic sandstone. In stratigraphic order these include the C, B, and A sandstones, the Marker Grit, and the Glassy Quartzite.

The top of the Glassy Quartzite unit is taken as the base of the Upper Roan Subgroup.

The Upper Roan Subgroup contains up to four depositional sequences below the level of breccia. These four sequences are present in drill hole L83 at Luansobe (Figure 4.10) that is used to illustrate the general geology of the area. In contrast to the Konkola area, the sequences in the eastern

ZCB contain abundant anhydrite; the thinly interbedded siltstone and sandstone, sand dikes, and red- weathering ferroan dolomite beds common at Konkola are uncommon or absent.

The two lower sequences in L83 have capping sandstone beds, the Middle Quartzite (UR1) and the Interbedded Shale and Quartzite (UR2) respectively. The two upper sequences, UR3 and UR4 are carbonate-evaporite dominant with massive anhydrite-carbonate beds at their tops. The UR4 sequence contains dolostones with minor greyish chert bands and quartz nodules, and is overlain by polylithic clast breccia (Figure 4.10). Similar siliceous dolostones are common above the level of breccia throughout the eastern ZCB, and are assigned to the Kansuki Formation forming the upper portion of the Upper Roan

Subgroup (Cailteux et al., 2007). 99

L83

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, Mwashya Subgroup

Siliceous dolomites (Kansuki Fm.)

Breccia complex

Upper Roan UR 4 Subgroup 200m

UR 3

UR 2 (ISQ) Glassy Qtzite UR 1 (MQ ) Marker Grit A Qtzite Lower Roan B Qtzite Subgroup Mindola Clastics Fm. C Qtzite Basement

Figure 4.10: Geological log of drill hole L83, Luansobe prospect, with insert showing simplified surface geology and location of studied drill holes. Surface trace of Luansobe fault estimated from drill data. L83 provides a near-complete section through the Katangan Supergroup. The Upper Roan Subgroup contains four depositional sequences below a thick breccia complex, discussed in text. Legend as in Figure 4.8.

100

Breccia throughout the eastern ZCB occurs in systematic stratal positions at or adjacent to contacts bounding the four depositional sequences. Variations in position and thickness of breccia can be related to local structural features interpreted as growth faults active during deposition of the Upper Roan

Subgroup. Breccia does not occur below the Glassy Quartzite unit at any of the localities studied in the eastern ZCB.

4.4.3 Eastern portion of the Zambian Copperbelt - Luansobe area

The Luansobe prospect occurs on the northern edge of the eastern ZCB adjacent the D.R.C. border to the east-southeast of the Konkola area (Figure 4.1 and Figure 4.10). The prospect is spatially associated with a basement high formed adjacent the Luansobe fault, which appears to be a westward extension of the Fitwaola fault in the Konkola area. There is little change in the thickness of the basal portion of the Lower Roan Subgroup throughout the Luansobe area. However, above this stratigraphic level there is a condensed (~100m) stratigraphic section to the north of the fault and a thickened section

~270 to 470 m thick to the south of the fault (Figure 4.10 and Figure 4.11). In the condensed section sequences UR1 and UR2 are present between the Glassy Quartzite and the base of breccia (drill holes L22 and L62) and only a single thin (~3 to 8 m) unit of polylithic breccia is present. To the south sequences

UR1 through UR3, and in drill hole L83 sequence UR4, are overlain by thick (~70 to 200 m) breccia complexes.

Breccias are positioned at or near the top of sequences. In the condensed section dolomite- anhydrite crackle breccia and stratigraphically equivalent polylithic clast breccia above the UR2 sequence represent the stratigraphically lowest occurrence of breccia (Figure 4.11). To the south of the basement high the base of breccia complex overlies massive anhydrite-carbonate at the top of the UR3 sequence

(drill holes L78 and L80; Figure 4.11). This breccia complex contains anomalously thick intervals of

101

Figure 4.11: Northwest-southeast strike section at Luansobe prospect, eastern side of Zambian Copperbelt. Detailed geology and correlation shows condensed section above structural high in the vicinity of drill hole L62, thick evaporitic sequences and breccia complex in depocenter to south. See text for discussion. Drill hole locations shown in Figure 4.10. Legend as in Figure 4.8, with additions as shown.

102 sandstone. Centimeter to meter-sized clasts (or beds) of massive anhydrite-dolomite rock within both the lower and upper parts of the breccia complex in drill hole L80 (Figure 4.4e) are compositionally and texturally similar to massive anhydrite-dolomite in UR3 and UR4 sequences.

The type of matrix in the polylithic clast breccias changes systematically within the Luansobe area. In the condensed section breccia matrix is dominantly dolomitic. To the south of the fault both dolomitic and phlogopite-chlorite matrix breccia are present (Figure 4.4g).

4.4.4 Eastern portion of the Zambian Copperbelt - Mufulira area

The Mufulira mine to the south of the Luansobe area in the eastern ZCB has three vertically stacked orebodies within northeast-dipping strata of the Lower Roan Subgroup (Brandt et al., 1961;

Fleischer et al., 1976; Annels, 1979). The distribution of the Mufulira orebodies and their host strata are controlled by ENE-trending basement highs which are interpreted as inverted fault blocks defining sub- basins (Figure 4.12; Fleischer, 1967; Annels, 1984; Selley et al., 2005).

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Figure 4.12: Simplified geology of the Mufulira area projected to surface, showing position of Mufulira orebodies and drill holes examined for this study. Basement-rooted structures bound depositional sub- basins that appear to have controlled the stratigraphic position of breccia, as well as distribution of mineralization. See text for discussion.

103

Three drill holes near the down-dip fringes of the orebodies intersected mineralized Upper Roan

Subgroup dolostones above one or more dolomitic matrix polylithic clast breccia unit (Figure 4.12; drill holes DH214, 218, 219). The basal polylithic clast breccia in the mine area lies approximately at the top of the UR1 sequence. Approximately 4.6 km along strike northwest towards Luansobe and 1 km to the northwest of one of the ENE sub-basin bounding faults, the stratigraphically lowest breccia lies above the

UR3 sequence (drill hole MW107, Figure 4.12 and Figure 4.13).

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Figure 4.13: Strike section through deep drill holes at Mufulira deposit. A thick breccia complex with abundant interleaved sandstone-(siltstone) occurs in the mine area (DH218, 219, 214), with the lowest breccia positioned at or near the top of sequence UR1. Outside the mine area and across a sub-basin bounding fault in drill hole MW107, the breccia complex overlies sequence UR3, is thinner, and interbedded carbonate rocks predominate over sandstone. Legend as in Figure 4.8, see text for discussion.

104

The Upper Roan Subgroup at the Mufulira mine contains a distinctive dolomitic siltstone to shaley unit known as the “Blue Shale”, which occurs with the UR2 (mine term, ISQ) sequence (Brandt et al., 1961). In drill holes DH218, DH219, and DH214 the Blue Shale occurs in its normal stratigraphic position in sequence UR2 despite the presence of underlying polylithic breccia at the top of sequence

UR1 (Figure 4.13; see also Wendorff, 2005a). In drill hole MW107 northwest of the mine the Blue Shale also is present, but below the base of breccia which occurs above sequence UR3 (Figure 4.13). This indicates that these breccias form laterally discontinuous ~stratiform units rather than cross-stratal fault structures.

The UR3 sequence in drill hole MW107 includes massive anhydrite-dolomite rock near its top, and is overlain by a polylithic breccia and ~350m thick breccia complex. A ~55m thick sandstone unit occurs in the lower portion of the breccia complex (Figure 4.13). In contrast in the deep mine area the total thickness from basal to uppermost breccia in the mine area is approximately 900 m. Included in this thickness is more than 300 m of sandstone in the lower and intermediate parts of the complex (Figure

4.13). The sandstone-dominated interval includes cycles of medium to coarse-grained, locally trough cross-bedded hematitic sandstone generally fining upwards to siltstone, dolomite or anhydritic dolomite.

Although individual beds cannot be correlated at the ~200 to 500m spacing of the drill holes examined, the sandstone packages appear to be lenticular (Figure 4.13). The exceptionally thick breccia complex and sandstone beds at the Mufulira mine are interpreted to mark a depocenter limited to the northwest by a bounding fault. Individual units of polylithic breccia thicken into this depocenter.

None of the drill holes provide stratigraphic constraints on the thickness of the Mwashya

Subgroup, but from available data it appears that the preserved thickness of the Upper Roan Subgroup is similar across the ENE fault (Figure 4.13). If polylithic breccia is representative of former evaporite beds original depositional thicknesses may have been much greater than now preserved.

105

4.4.5 Eastern portion of the Zambian Copperbelt - Itawa area

The Itawa area to the southeast of Mufulira (Figure 4.1) is centered on a local basement-cored anticlinal structure (Figure 4.14). There are no apparent thickness changes of the Lower Roan Subgroup at Itawa as observed at Konkola. The Upper Roan Subrgroup succession at Itawa contains fewer sequences than that at Mufulira. From the north to the south flank of the anticline at Itawa the stratal packages in the Upper Roan succession thin by approximately 80 percent (Figure 4.15). As at Luansobe, breccia occurs consistently at or near a stratigraphic transition from anhydrite-carbonate to siliceous carbonate. The combined Mwashya Subgroup - Grand Conglomerate Formation section above the Upper

Roan Subgroup at Itawa also thins to the south.

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Figure 4.14: Geological map and drill plan, Itawa prospect, Zambia (modified from Binda and Van Eden, 1972).

106

Limestone 0’ IT28 Diamictite Chert nodules, beds Sh-slst Magnesite 0’ IT27

Intb.dol + slst v Anhydrite Nguba Evap carb + chert/qtz Autolithic slst bx Evap cgl breccia Evap carb + slst 1000’ Evaporitic carbonate Siltstone, slst + dol 1000’ Mwashya Sst + arg sst, dol 0’ IT26 Arkosic sst, cgl Basement 2000’ 0’ IT25

2000’ Kansuki 1000’ 300 m 3000’ 1000’

3000’ 2000’ Upper Roan

4000’ 2000’ 4000’ 3000’ L. Roan

5000’ 1700m NW 800m ENE ! 3250m N! ! Basement

Figure 4.15: South-north drill section of geological logs of drill holes through Itawa prospect, Zambia. Section datum is the top of Lower Roan Group. Note the ~80% stratal thinning within the Upper Roan Group from north to south, without significant pinchout of major stratal units. See text for discussion.

107

The condensed section in the southern Itawa area, represented by drill hole IT26, contains a ~36 m thick UR1 sequence above the Glassy Quartzite (Figure 4.15 and Figure 4.16) consisting of evaporitic carbonate-anhydrite rock, siltstone, and multiple breccia types that culminate in a polylithic clast breccia that is overlain by siliceous dolostones of the Kansuki Formation (Figure 4.17). The lower portion of this

UR1 sequence displays ~0.5 to 5 m cycles of greyish, poorly bedded argillaceous sandstone each of which grade upwards to evaporitic carbonate (Figure 4.17). The lowermost cycle contains dolomite and abundant, commonly nodular white magnesite, while the overlying cycles contain anhydrite in addition to

2450’ v

Chert nodules, beds

Magnesite v Anhydrite

Sandy matrix polylithic clast breccia 2500’ Monolithic siltstone breccia

v Evaporitic carbonate v Siltstone

Argillaceous poorly bedded sandstone

2550’ Feldspathic poorly bedded sandstone

(Glassy Qtzite, top of Lower Roan Subgroup)

v v 10 m 2600’ Upper Roan

Lower Roan 2650’

Figure 4.16: Geological log for part of drill hole IT26, Itawa prospect, Zambia, showing the evaporitic carbonate-breccia UR1 sequence overlain by siliceous dolostones of the Kansuki Formation.

dolomite and magnesite. The middle part of the UR1 sequence contains alternating beds of massive carbonate-anhydrite and green to brown siltstone (Figure 4.18); the siltstone beds are weakly disrupted

108

` siliceous dolomites

polylithic breccia

monolithic breccia

Interbedded carb-anhy / monolithic breccia

interbedded carb-anhy / siltstone v v evaporitic cycles

Figure 4.17: Composite photograph of drill core from the brecciated portion of the UR1 sequence presented in Figure 4.16. circle = top of evaporitic cycle; ∧ = base of anhydrite; contacts shown as vertical yellow lines for: base of in-situ brecciated siltstone beds; base of evaporitic carbonate-matrix monolithic siltstone breccia; base and top of polylithic clast breccia.

109 a. b. 5

3 4

4 3 2 1

1 c.

e. f.

Figure 4.18: Breccia sequence in drill hole IT26. (a) interbedded evaporitic carbonate and in situ brecciated/replaced siltstone beds (b) carbonate-evaporite matrix siltstone breccia; (c) sequence of (1) massive dolomite-magnesite-anhydrite evaporite → (2) dark siltstone → (3) carbonate-evaporite matrix monolithic siltstone breccia → (4) polylithic clast breccia → (3) autolithic and monolithic breccia → (5) bedded evaporitic carbonate + siltstone with chert nodules and beds. (d) closeup of polylithic breccia, showing rounded, spheroidal, sand to pebble-sized clasts/grains in dolomitic cement; ~2cm brown stick for scale. (e) interbedded grey chert and dolomite, overlying polylithic breccia; core width ~5cm (f) grey quartz nodules at top of dolomitic cycle; core width ~5cm.

and partially replaced by carbonate and anhydrite (Figure 4.18a). The upper part of the UR1 sequence contains massive carbonate-anhydrite layers alternating with layers of monolithic clast breccia, wherein

110 disrupted and partially replaced siltstone occurs as isolated to juxtaposed clasts within a matrix of coarse carbonate and anhydrite (Figure 4.18b). The clasts generally display irregular subangular to subrounded rather than rounded shapes. The monolithic breccia contains layers with either green or brown siltstone clasts demonstrating preservation of the original stratification.

The UR1 sequence culminates with a ~one meter-thick massive-bedded dolomitic matrix polylithic clast breccia (Figure 4.18c, d) that consists of 30-50% fine sand to pebble-sized, subround to round clasts of siltstone, sandstone and subangular coarsely crystalline dolomite and anhydrite in a slightly ferroan, dolomitic matrix. Some lithic clast rims are altered to the matrix composition. The clasts and grains are unsorted, ungraded, lack any preferred alignment or imbrication, and show no evidence of cataclasis. This breccia is overlain by ~30 cm of anhydrite-rich autolithic breccia that is turn overlain by

~3 m of interbedded massive carbonate ± anhydrite and weakly brecciated siltstone. This is capped by thick-bedded siliceous dolostones with thin siltstone interbeds typical of the Kansuki Formation. The siliceous dolostones contain grey cherty quartz beds (Figure 4.18e) and nodules of rounded to subangular, mm to cm-sized translucent grey quartz at the tops of evaporitic carbonate cycles (Figure 4.18f).

The UR1 sequence in drill hole IT26 documents progressive upwards development of breccia in evaporitic rocks. The preservation of compositional layering within the breccia sequence and the presence of autolithic breccia in the immediate hangingwall of the polylithic breccia are consistent with development of the polylithic breccia by more or less in situ processes.

4.4.6 Southwest portion of the Zambian Copperbelt - Chambishi basin area

The Chambishi Basin area lies west of the Kafue dome in the southwestern part of the ZCB, approximately 40 km southeast of Konkola and 25 to 30 km southwest from Mufulira and Luansobe

(Figure 4.1). Data on breccias in this area are derived primarily from drill hole RCB2 in the west-central part of the basin that has also been described by Bull et al. (2011) and Woodhead (2013), and drill holes

BN42 and BN43 approximately 8 km to the west-southwest that also were described by Wendorff

(2005b) and Selley et al. (2005) (Figure 4.19). 111

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300m

Mafic breccia complex

400m UR4

500m Upper Roan Subgroup UR3 600m

Shallowing-upwards sequence 700m Mafic rock, mafic–associated breccia

Polylithic breccia with 800m UR2 dolomite-albite matrix

Cyclic siltstone-carbonate- anhydrite, massive 900m carbonate-anhydrite rock at top UR1

Siltstone-sandstone- 1000m carbonate, weakly or non- evaporitic (Antelope Clastics Mbr) 1100m Chambishi Dolomite Member RCB2 b.

Figure 4.19: Chambishi basin area. (a) Simplified geological map, showing position of drill holes RCB2 and BN42, 43 discussed in text. (b) Simplified log of middle portion of drill hole RCB2. The Upper Roan Subgroup is interpreted to consist of four shallowing-upwards depositional sequences, with 10 to 50% anhydrite in beds in the upper parts of the sequences. The second and third sequences are overlain by albite-dolomite matrix polylithic breccia, interpreted as former evaporite. The fourth sequence is overlain by mafic rocks and mafic-associated breccia transitional to the Mwashya Subgroup.

112

The total thickness of the Upper Roan Subgroup sequence including the transitionally underlying

Antelope Clastics Formation is more than 500 m in the Chambishi basin in drill hole RCB2 (Figure

4.19b). With inclusion of the underlying Kitwe Formation at least 600 m of stratigraphy is missing in drill holes BN42 and BN43 to the west across an inferred basin margin/master fault (Annels, 1984; Selley et al., 2005; Wendorff, 2005b). Further southwest there are few drill holes but geological mapping outlines a large area of “albitized dolomitic breccia” with abundant associated mafic bodies (Garrard, 1965) underlain by quartz-sericite schists and overlain by “biotite spangled schist” interpreted as equivalent to the Mwashya Subgroup.

Breccia in the Chambishi basin displays a regional westward and southward “down-stepping”

(Annels, 1984; Binda and Porada, 1995; Porada and Berhorst, 2000). South of the Mwambashi B deposit and at the Chibuluma deposit and further westward, a mafic-associated breccia complex lies directly on rocks of the Mindola Clastics Formation of the Lower Roan Subgroup, such that the Copperbelt Orebody

Member and the upper part of the Kitwe Formation are absent (so-called Ore Shale cutout; Figure 4.19a).

Annels (1984) interpreted this “cutout” as a rift margin fault. The inferred fault parallels major lithostructural trends in the basement (Figure 4.1 and Figure 4.19a) and would form one of the “master faults” envisaged by Selley et al. (2005), similar to the faults at Konkola and Luansobe. The main

Chambishi basin would thus represent a depocenter within which the upper Kitwe Formation and Upper

Roan Subgroup sequences are preserved. Although data are limited it appears that the Mindola Clastics

Formation of the Lower Roan Subgroup is not condensed or eroded west of this structure (Binda and

Porada, 1995; Wendorff, 2005a; Woodhead, 2013), which would suggest that movement on the fault occurred primarily during or after deposition of the Copperbelt Orebody Member and the evaporitic sequences of the upper Kitwe Formation and Upper Roan Subgroup.

Four evaporitic sequences UR1 through UR4 overlying the Antelope Clastics Member are present in drill hole RCB2 (Figure 4.19b). Each sequence contains a lower portion where evaporitic textures and anhydrite are minor or absent and an upper portion with more abundant evaporitic textures and anhydrite.

The UR2 through UR4 sequences are thicker, at least in part due to intraformational recumbent folding, 113 but otherwise the sequences are similar in overall character to those at Konkola and in the eastern ZCB.

As in other localities breccia occurs systematically at or near the tops of sequences (Figure 4.19b).

The base of the lowest sequence UR1 is transitional from the underlying Antelope Clastics Formation and as at Konkola is defined by the first appearance of carbonate beds. The sequence contains typical anhydritic siliciclastic-carbonate evaporite cycles (Figure 4.6b, c) capped with thick beds of nodular and interbedded carbonate-anhydrite. Fine-grained magnesite is the dominant carbonate. High-resolution

QEMSCAN imaging indicates that magnesite and albite are replacive after early anhydrite and that trace halite is present in association with minor apatite (Woodhead, 2013).

Sequence UR2 commences with a ~50 m anhydrite-poor interval containing three thick units of lenticular-bedded feldspathic sandtone and lesser siltstone with intervening units of recrystallized dolomite-magnesite rock. Secondary K-feldspar and lesser albite feldspar replace the carbonate minerals and contain inclusions of anhydrite (Woodhead, 2013). The intensity of alteration suggests this unit was a major fluid pathway. The remainder of the UR2 sequence consists of cycles with alternating beds of quartz granule siltstone-sandstone and beds of nodular to enterolithic magnesite/dolomite-anhydrite; the sandstone beds locally contain sandstone dikes. The UR2 sequence is capped by albite-dolomite matrix polylithic breccia. The lower section of the breccia is intensely altered to quartz, albite and weakly ferroan dolomite and magnesite. This alteration locally obscures clast outlines. The upper portion of the breccia displays a more typical texture with angular to rounded clasts.

The UR3 sequence commences with a thick interval of limestone and/or dolostone. Bedding is poorly preserved in this unit but pyritic stylolites are recumbently folded. This interval appears to be approximately 100 m thick. The interval locally displays a vuggy texture but lacks siliceous or cherty beds and nodules. It is overlain by ~70 m of anhydritic dolostone alternating with dolostone and dolomitic siltstone intervals that locally display sheared fabrics, followed by albite-quartz-carbonate matrix polylithic breccia. The breccia matrix is composed primarily of albite with intergrown anhedral quartz. It contains round grains of inclusion-poor quartz that may be detrital or replacive after rounded grains or clasts (Woodhead, 2013). 114

The UR4 sequence consists of a ~70 m interval of rhythmically thin-bedded and graded non- evaporitic ferroan dolomitic sandstone-siltstone beds. Individual intervals are capped by siltstone or shale.

The top of the sequence is occupied by poorly bedded, vuggy talcose dolomite that contains anhydrite.

The UR4 sequence in drill hole RCB2 is overlain by a thick complex of mafic rocks, mafic-associated breccia, carbonate rocks transitional to the Mwashya Subgroup, and collapse breccia with angular fragments of black pyritic shale characteristic of the overlying Mwashya Subgroup. Albite-quartz alteration dominates the base of the complex. Inclusion-poor round quartz grains again are present in breccia matrix and the carbonate rocks are commonly silicified (Woodhead, 2013).

The sequences in drill hole RCB2 are comparable and correlatable with those in the other localities studied in the ZCB. In each locality evaporitic rocks and breccia are positioned systematically towards the top of each sequence. A vertical progression from non-evaporitic to evaporitic beds in each sequence also occurs laterally within the Chambishi basin. There is an increased abundance of anhydrite and decreased siliciclastic grain size, particularly in the Rokana Evaporites Member of the upper Kitwe

Formation (Woodhead, 2013), to the west. These lateral facies changes mirror lateral facies changes present below the Copperbelt Orebody Member. In drill hole RCB2 the footwall sandstone is anhydrite- rich (Woodhead, 2013) but becomes more dolomitic to the east at Chambishi SE. The breccias in the

Chambishi basin occur at the lowest stratigraphic position of highly evaporitic rocks within the local section.

4.4.7 Kamoa deposit, western margin of the Congolese Copperbelt

The Kamoa deposit occurs in basal strata of the Grand Conglomerate Formation approximately

20km west of Kolwezi, at the western extremity of the DRC Copperbelt adjacent the Nzilo basement block (Figure 4.1 and Figure 4.20; Broughton and Rogers, 2010; Schmandt et al., 2013). Its autochthonous setting is analogous to that of deposits in the ZCB.

The Kamoa deposit occurs in a proximal position to the Nzilo basement dome to its north, above

or adjacent a condensed section of Roan Group rocks (Figure 4.20). Along the northernmost edge of the 115

$ % $ ! & ' ( % ( ! & ' (! "# ( ! "# " "

! ' *+)+,

-)*+, )

Figure 4.20: Simplified geological map of Kamoa area showing location of drill hole DMAK-DD009, discussed in text.

deposit the Roan Group is absent or represented by less than a few hundred meters of siliciclastic sedimentary rocks. Near the southern edge of the deposit across the east-northeast trending Makalu fault the Roan Group is at least 1600 m thick in drill hole DMAK-DD009. These relationships indicate that this east-northeast-trending fault was active during Roan Group sedimentation similar to the master faults in the ZCB. The Roan Group in this southern area contains evaporitic sequences and polylithic breccia, both of which are absent from the condensed section to the north.

The Roan Group in drill hole DMAK-D009 contains a lower sequence in which the drill hole terminated, characterized by thick units of poorly bedded evaporitic siltstone. This is overlain by a middle sequence with shallowing upwards siltstone-evaporitic carbonate cycles and an uppermost sequence of

116 generally coarse-grained siliciclastic rocks. The lower sequence includes a ~6.5 m thick breccia complex with massive anhydrite-dolomite evaporite and polylithic clast breccia (Figure 4.21 a-h). The evaporitic rocks and breccia at Kamoa are lithologically equivalent to rocks in the Upper Roan sequence of the ZCB, although their stratigraphic position within the Roan Group remains uncertain.

The breccia complex is underlain by predominantly unbrecciated hematitic siltstone with evaporitic nodules and minor in situ autolithic breccia. The hematitic siltstone is overlain by ~20 cm of thinly bedded siltstone and sandstone (Figure 4.21b) that is conformably and sharply overlain by the 6.5 m thick breccia–evaporite complex. The breccia complex contains similar lower and upper intervals of clast-supported polylithic breccia separated by a ~3 m interval of anhydrite-dolomite evaporite (Figure

4.21a). Both intervals of polylithic breccia have a sandy matrix (Figure 4.21c) and contains clasts that are subrounded to angular, close-packed, and primarily composed of green chloritic siltstone. Both the matrix and clasts within the lower interval of polylithic breccia are locally replaced by patchy grey-white coarse- grained dolomite (Figure 4.21d,e). Clasts of the footwall hematitic siltstone are absent within both polylithic breccia intervals. The lower contact of the anhydrite-dolomite rock separating the polylithic breccia intervals is conformable with the underlying breccia (Figure 4.21f). The anhydrite-dolomite rock locally contains ferruginous dolomite similar to that in the Upper Roan Subgroup at Konkola mine

(Figure 4.21g). The upper boundary of the anhydrite-dolomite rock is irregular. Steeply dipping apparent injections and discontinuous lenses of the anhydrite-dolomite rock are present in the overlying polylithic breccia (Figure 4.21h). The upper polylithic breccia interval lacks replacive dolomite and grades upwards to in situ autolithic breccia containing clasts of chloritic siltstone similar to the clasts in the underlying polylithic breccia. Sandstone beds overlying the in situ autolithic breccia are disrupted by extensional fractures or microfaults infilled with siltstone from the overlying beds consistent with development of a collapse breccia (Figure 4.21a).

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Figure 4.21: Breccia and evaporite in Roan Group stratigraphically ~1400m below the base of Grand Conglomerate unit, hole DMAK-DD009, south of Kamoa area. (a) overview of core with annotated positions of detailed photographs. (b) hematitic massive purplish siltstone with minor nodular anhydrite- dolomite (lower core), overlain by thin-bedded tan siltstone and sandstone marking base of breccia (to left), sandstone is partially replaced by grey-white dolomite. (c) polylithic breccia with sandy matrix and green siltstone clasts (d, e) partial to near-complete replacement of breccia by coarse white dolomite- anhydrite, note clasts of green nodular siltstone and lack of footwall hematitic siltstone clasts. (f) base of massive dolomite-anhydrite bed, with replacement of underlying breccia. (g) red ferruginous dolomite- anhydrite rock within massive dolomite-anhydrite bed. (h) upper part of anhydrite-dolomite bed is mobilized into lenses, with possible dissolution zone outlined by orange-red dolomite seam. Overlying polylithic breccia is similar to the breccia in the footwall of the evaporite, and grades up-hole into in situ autolithic brecciated siltstone.

118

slump-brecciated sandstone

in situ autolithic breccia polylithic breccia h

disrupted/mobilized evaporite

anhydrite-dolomite evaporite g

d e f altered polylithic breccia sandstone polylithic breccia c / / b

hematitic siltstone a.

Figure 4.21: continued.

119

f. g.

Figure 4.21: continued.

Formation of the upper dolomitic polylithic clast breccia at Kamoa is interpreted as a two-stage process, involving generation of a collapse breccia by partial withdrawal and/or dissolution of evaporite followed by dolomitization in the footwall of the evaporite body. The lower polylithic breccia may have formed similarly, with the thinly bedded sandstone and siltstone at its base marking the original position of evaporitic rocks.

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4.5 Geochemical studies

Previous work has demonstrated that marine C and O isotopic signatures are preserved in dolomite rocks of the ZCB and that strongly negative C isotopic signatures (δ13C –5 to -26‰ PDB) are associated with oxidation of organic carbon during mineralization of Lower Roan Subgroup strata (Selley et al., 2005). Carbon and oxygen isotopic data were collected for the current study from dolomite in beds, breccias, and nodules in the Upper Roan Subgroup (Figure 4.22; Appendix D).

Figure 4.22: Carbon and oxygen isotopic data for carbonates in ZCB, this study. (a) All data. A negative d13C trend associated with Lower Roan Subgroup mineralized strata is absent from overlying rocks. (b) Upper Roan Subgroup data from dolomite rocks, breccia and diagenetic nodules. A primary signature is recorded in a cluster of data from dolomite beds and “chicken wire” dolomite with d18O values of ~23- 26‰. Dolomitic nodules, altered beds, crackle breccia and polylithic breccia define a negative d18O trend, consistent with higher temperature of formation and/or a meteoric source.

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Sedimentary signatures are recorded in dolomite from both massive and “chicken wire” dolostone beds. Samples of dolomite from diagenetic nodules, crackle breccia, and polylithic breccia display a moderate to strong shift to lighter δ18O values. They do not, however, show a significant shift to lighter

δ13C values, despite the presence of subeconomic concentrations of Cu-Co sulfides in some of the samples from the Mufulira mine. The data suggest the dolomite within the breccias formed from moderate to high temperature brines or from meteoric water but did not precipitate in the presence of hydrocarbons.

Previous studies have documented a stratigraphic partitioning of K and Na in the ZCB (Selley et al., 2005). Rocks of the Lower Roan Subgroup have high K2O values and essentially no Na2O whereas overlying rocks of the Upper Roan and Mwashya subgroups have moderate to higher Na2O values, respectively. The moderately elevated Na2O values are spatially associated with the development of evaporitic carbonate-anhydrite facies, and the higher values with polylithic clast breccia and overlying rocks of the Mwashya Subgroup. This sodic alteration could have resulted from interaction of the sedimentary rocks with brines derived from precipitation of halite (residual brines) or dissolution of halite.

In order to evaluate the possible roles of residual and/or dissolution brines in the ZCB, a reconnaissance study of fluid inclusion compositions from ore-stage sulfides and a variety of dolomite types was conducted using the crush-leach techniques described in Viets et al. (1996). Molar ratios of

Cl/Br versus Na/Br of fluid inclusion solutes are useful in constraining the origin of salinity in fluid inclusions, in particular for distinguishing fluids formed as residual brines during halite precipitation

(McCaffrey et al., 1987; Viets et al., 1996) versus brines derived from dissolution of halite.

Fluids within inclusions in ore sulfides in the lower Roan Group appear to have been derived from marine residual brines that in many instances had evolved past halite saturation (Figure 4.23). In contrast, fluids from inclusion in ore sulfides from the Kipushi deposit positioned stratigraphically above the level of breccia appear to have been derived, at least in part, from halite dissolution. Other studies at

Kipushi have confirmed this fluid signature (Heijlen et al., 2008) and suggest a post-Lufilian age (451 122

Ma) for mineralization (Schneider et al., 2007). In the absence of significant halite being present in the

Roan Group rocks or the presence of casts after halite, these results are the best evidence that halite was deposited in the Roan Group.

# " ! " / " #

$% ! "

$% ! & '() *& +,- "(! &* . $ #"

Figure 4.23: Molar ratios of Cl/Br versus Na/Br of fluid inclusion solutes from the Zambian Copperbelt. The seawater evaporation line represents the direction of Cl/Br and Na/Br molar ratio change in residual brines as seawater evaporates and precipitates evaporite minerals (after McCaffrey et al., 1987). The halite dissolution line represents the trajectory of Cl/Br and Na/Br molar ratio change in brines with an increasing component of salinity from dissolution of halite. Sulfides from ZCB deposits and evaporitic dolomite from the Upper Roan fall close to the seawater evaporation line, indicating fluids formed from residual brine and that seawater passed halite saturation, i.e. halite was deposited. Dolomite from mineralized fibre veins and particularly from dolomitic matrix incipient and polylithic breccias in the ZCB have molar ratios indicating these fluids incorporated salinity from dissolution of Na evaporites, including a non-marine (non-halite) component. In contrast a sample of breccia from Kolwezi, DRC has a halite dissolution signature. See text for discussion.

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Crush-leach fluid data were also collected from several types of dolomite within the UR1 sequence in the Konkola area and from dolomite in the matrix of incipient breccia and polylithic clast breccia from the Chambishi basin, Konkola, and Mufulira areas. Dolomite from an unmineralized evaporitic nodule in the UR1 sequence at Konkola contained inclusions with fluid compositions indicative of derivation from residual marine brine (Figure 4.23). In contrast, inclusions in the UR1 sequence of nodular and fibre-vein dolomite intergrown with chalcopyrite at Konkola contained fluids with molar ratios indicative of dissolution of mixed halite and/or non-marine sodic evaporite.

Chalcopyrite from one of these samples (drill hole KN18, 1227.6 m) returned a Re-Os age of 825 ± 65

Ma (Barra et al., 2004) indicating that chalcopyrite formation, and by association dissolution, occurred at least ~150 m.y. prior to Lufilian inversion. Inclusions in dolomite from the matrix of incipient breccia in the Chambishi basin (Nkana West drill hole WL73, Figure 4.19) and from polylithic clast breccia at the

Konkola and Mufulira deposits also contained fluids that display sodic dissolution signatures, particularly at Mufulira (Figure 4.23). The fluids with sodic dissolution signatures have Na/Cl ratios of greater than one and a distinctive Na-SO4-HCO3-Cl signature. These data may indicate addition of Na from a meteoric fluid, most likely due to dissolution of non-marine Na-minerals in addition to halite (Emsbo, pers. comm.,

2007). This is consistent with the basin-marginal position of the ZCB. One sample of breccia from the allochthonous Kolwezi district in the CCB also shows a dissolution signature, but without a non-marine influence. This suggests along with the halite dissolution signature at Kipushi that dissolution brines in the CCB were derived primarily from marine evaporites, consistent with a basin-central position.

4.6 Discussion

The origin of breccias in the CACB breccias has historically been discussed from the viewpoint of the breccias in the Congolese Copperbelt. A key relationship noted by François (in Demesmaeker et al., 1963; and 1973) in the Kolwezi district of the CCB is that the breccias lie below Roan Group rocks that themselves were emplaced above younger upper Kundelungu Group strata. These breccias were interpreted primarily as tectonic (faults, mylonites) formed during emplacement of nappes. 124

François (1973) noted that the Roan Group rocks may have contained evaporites that could have provided a locus for deformation and décollement and been involved in the formation of the breccias. Many subsequent publications dealing with the geology of the Congolese Copperbelt adhered to this tectonic model of breccia formation facilitated by evaporites (François, 1974, 1993, 2006; De Magnée and

François, 1988; Bell, 1989; Cailteux and Kampunzu, 1995; Kampunzu and Cailteux, 1999).

Other authors, however, proposed a sedimentary origin for the breccias. Bartholomé et al. (1972) interpreted breccia within the upper part of the R.A.T. Subgroup at Kolwezi as conglomerate deposited on an erosional surface. Grujenschi (1978) conceived a sedimentary “wildflysch” model for the DRC megabreccia. Wendorff (2000a, b, 2003, 2005a, b) noted that the matrix-supported texture of polylithic clast breccia in the DRC is comparable to that of conglomeratic debris flow deposits. He observed that other textural characteristics of the breccias, such as compositional layering and the occasional presence of detrital grains, would be consistent with such an origin. Wendorff concluded that the megabreccias of the DRC as well as breccia complexes at Mufulira and Mwambashi B in the ZCB formed as olistostromes

(Wendorff 2000a, b, 2003, 2005a, b). However, a conglomeratic model of breccia formation is incompatible with the characteristic round clast shapes in the breccia, does not account for the strong association of breccia with evaporitic rocks, and is inconsistent with the systematic position of breccia within the evaporitic sequences.

The location of breccias at the boundaries between successive shallowing-upwards sequences, many of which contain anhydrite, indicates the breccias are genetically related to evaporitic rocks as suggested by François (1973). The evidence for local replacement of evaporitic minerals in the breccias by dolomite, the gradational contacts between in situ autolithic and polylithic breccia, and the composition of fluids in inclusions in breccia matrix dolomite also suggest that dissolution of evaporitic minerals, including halite, were involved in breccia formation. However, halite is rare to nonexistent in the sequences hosting the breccias.

The breccias in the Zambian Copperbelt, like those in the Congo, have been interpreted as marking the positions of major low angle faults (Cailteux et al., 1995; Kampunzu and Cailteux, 1999; 125

Porada and Berhorst, 2000). However, as noted by Selley et al. (2005) the lack of structural repetition of footwall strata above the position of breccia makes breccia development in the ZCB difficult to reconcile with a strictly thrust-tectonic origin.

Bull et al. (2011) considered breccias in the ZCB as part of an evaporitic carbonate (“massive white dolomite”) facies deposited during periods of sea level transgression or high stand. Woodhead

(2013) interpreted breccia primarily as recording a substantive lowering of sea level associated with basin isolation and deposition of evaporite (evaporitive drawdown).

Detailed stratigraphic correlation demonstrates that breccias in the ZCB are systematically associated with evaporitic shallowing-upwards sequences with individual breccia layers largely confined to the most evaporitic portions of the sequences. The stratigraphic data indicate that breccia may occur at different stratigraphic levels over relatively short distances. This “down-stepping” of breccia within the stratigraphy was first documented by Brandt et al. (1961) at the Mufulira deposit, and subsequently has been demonstrated throughout the ZCB (Annels, 1984; Binda and Porada, 1995; Selley et al., 2005;

Wendorff, 2005a, b; this study). These geometries are interpreted as being directly related to the presence and location of major growth faults, which appear to have controlled the thicknesses of the ZCB breccia complexes.

In the western ZCB, extension during Mwashya time on major growth faults probably controlled the emplacement of shallow-level mafic sills or extrusive flows into the predominantly unlithified basin fill, producing distinct breccias mainly above the evaporitic sequences. In the hangingwall condensed section emplacement occurred directly into evaporitic strata.

Breccias in the ZCB are folded and were clearly locally subjected to low angle faulting during

Lufilian basin inversion. The hangingwalls and/or locally the footwalls of many breccias commonly display foliated fabrics. Such zones commonly occur above an albitized zone that appears to have insulated the breccia and its margins from deformation. The breccias themselves, however, rarely display deformational fabrics or evidence of cataclasis. This lack of a deformation fabric is problematic for a

126 thrust-tectonic model for breccia formation (Brandt et al., 1961; Binda and Porada, 1995; Selley et al.,

2005).

Many of the breccia complexes in the DRC crosscut stratigraphy. They display geometries similar to salt walls and diapirs observed in many evaporite provinces (De Magnée and François, 1988;

Jackson et al., 2003). Breccias in the ZCB are primarily concordant and occur as semi-continuous to lenticular bodies along stratal contacts. Discordant, apparently halokinetic breccias piercing strata of the

Mwashya Subgroup, Nguba and Kundelungu groups such as those in the CCB are not observed in the

ZCB. While thick evaporitic sequences including halite could have been deposited in the ZCB, the lack of discordant breccia would require its early dissolution. The apparent absence of halite in the ZCB and at

Kamoa suggests that insufficient accommodation space was generated in these basin margin positions to allow for the accumulation of significant thicknesses of halite as occurs in deep water “saline giants”

(Warren, 2006) and probably was present in portions of the Congolese Copperbelt (Jackson et al., 2003).

Though halite was probably deposited in the ZCB it appears that accumulations did not reach sufficient thicknesses to allow for halokinesis.

If the ZCB breccias did not form from halokinesis as at least some apparently did in the CCB breccias, other origins must be examined. Replacement by dolomite of an original evaporite phase(s) that formed some or all of the breccia matrix is a possible mode of origin. The absence of halite in the ZCB suggests that if halite was not dissolved it was nearly completely replaced by carbonates.

Alternatively, the evaporitic sequences within the ZCB could have been dominated by calcium sulfate as might be expected in a basin margin position. There is petrographic evidence of anhydrite inclusions in carbonate and albite, but wholesale replacement of anhydrite, the most common evaporite mineral present in the ZCB, appears problematic. Breccias in the ZCB occur directly in contact with and/or contain clasts or interbeds of massive carbonate-anhydrite rock. There is no textural evidence in such rocks for replacement of anhydrite by coarse-grained carbonate-albite characteristic of the breccia matrix. There is also a general paucity of pseudomorphs after evaporitic minerals, including sulfates.

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Carbonate replacement of anhydrite or halite would have resulted in ~50% to 100% volume expansion, whereas carbonate replacement of gypsum produces an approximate 15% volume loss and would have allowed for continuous replacement by creation of increased permeability (Altinok, pers. comm. 2013).

Gypsum is rare in the ZCB. Gypsum is converted to anhydrite at temperatures of ~60oC (Warren, 2006).

Thus, if gypsum replacement by carbonate was a primary means of breccia formation in the ZCB brecciation must have occurred prior to burial of the Upper Roan Subgroup sequence.

Breccias in the ZCB could also have formed from dissolution of evaporite beds. Evaporite dissolution produces diagnostic sedimentological features including structural disruption of hangingwall strata, collapse breccia with preservation of former layering, and deposits of residual silt/clay originally interbedded with the evaporite (Warren, 2006). There is little evidence of widespread collapse or disruption of strata overlying the breccias in the ZCB. However there is local evidence of autolithic breccia developed above breccia and abundant development of autolithic breccia within breccia complexes. At Kamoa, where polylithic breccia is not replaced by dolomite it exhibits clast-supported and angular textures diagnostic of collapse. It also is overlain gradationally by in situ autolithic breccia and by collapse/slumping features in sandstone. The ZCB polylithic breccias generally lack such textures, but do commonly preserve a compositional layering represented by clast type and abundance. The ZCB breccias also were subject to texturally destructive dolomite-albite-quartz alteration such that clast boundaries are obscure. Some ZCB breccia complexes include very clast-poor layers possibly representative of residual clay.

Alteration and veining of footwall strata also are diagnostic features of evaporite dissolution breccia (Warren, 2006), commonly whereby gypsum dissolved during formation of collapse breccia is reprecipitated as veins. Although gypsum is rare in the ZCB, anhydrite-carbonate veins are a common feature in the footwall of breccia and are interpreted to have formed either via conversion of gypsum to anhydrite or dissolution and reprecipitation of primary anhydrite. The common presence of dolomite- albite alteration within and below breccia and breccia complexes is consistent with this model.

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Evaporitic strata similar to that in the ZCB occur in the correlative Neoproterozoic strata of the

Damaran Supergroup in Namibia. There, the Duruchaus Formation comprises a cyclical evaporitic sequence (Behr et al., 1983) with evaporitic cycles and sequences similar to those of the Roan Group.

From basinward to landward these include non-evaporitic laminated siltstone and fine sandstone, playa mud flat facies laminated mudstones and ferruginous albitic dolomite with non-marine evaporite mineral pseudomorphs, and exposed saline mud flat facies with albitolites (former salt crusts) occurring as clasts within ferruginous dolomite-albite matrix breccias (Behr et al, 1983). The cycles in the Duruchaus

Formation include a marginal siliciclastic facies. Behr et al. (1983) interpreted much of the Duruchaus

Formation as forming in a lacustrine depositional environment based on the variety and abundance of non-marine evaporite pseudomorphs.

The dolomite-albitolite breccias form both concordant and discordant features. Concordant breccia is interpreted as due to growth and dissolution of evaporite and to syneresis in the sedimentary or early diagenetic environment (Behr et al. 1983). Breccia was later mobilized into discordant dikes and pipes and lit-par-lit injections due to overpressuring during the emplacement of nappes more than 100 m.y. after deposition of the evaporites (Behr et al., 1981).

The evaporitic cycles in the Upper Roan Subgroup in the ZCB lack the non-marine evaporite pseudomorphs and tabular albitolite clasts after salt crusts such as are present in the Duruchaus

Formation, and instead contain an abundance of nodular magnesite and dolomite suggestive of marine conditions. However, dissolution of non-marine Na evaporite minerals is consistent with the unusual high

Na/Cl ratios of fluids in inclusions from breccia matrix and certain evaporitic nodules in the ZCB. This would be consistent with the basin-marginal position of the ZCB.

4.7 Conclusions

Observations in the Zambian Copperbelt and at Kamoa suggest that breccia formation in these areas occurred through a combination of evaporative dissolution and collapse and late texturally

129 destructive dolomite/magnesite-albite alteration. Replacement of primary evaporite by carbonate and albite is considered to have played a lesser role.

In the Zambian Copperbelt, most Lower Roan age early syn-rift stage extensional faults became inactive following widespread fault linkage during Copperbelt Orebody Member time (Selley et al.,

2005). A period of relative tectonic quiescence followed, during which multiple sequences of variably carbonate-evaporitic and siliciclastic strata were deposited, beginning with the Rokana Evaporites

Member in the western ZCB. In positions proximal to sediment supply, sequences consisted mainly of siliciclastic strata, whereas more distal positions also accumulated carbonate-anhydrite evaporites. In all areas a general shallowing-upwards trend records a gradual increase in evaporitic strata (i.e. a “brining- upwards”). Sequences can be correlated between different portions of the ZCB, but local structural depocenters developed due to continued or renewed movement on major growth faults. Deposition of carbonate and gypsum occurred in most areas, but deposition of halite was minimal. The most significant thicknesses of evaporites, probably including minor halite, were deposited immediately prior to or during a transition to widespread basin extension in late Upper Roan and early Mwashya Subgroup time. A change to open marine conditions is marked by non-evaporitic siltstones and shales of the Mwashya

Subgroup and in proximal positions or on structural highs by the poorly evaporitic massive dolostones of the Kansuki Formation.

Dissolution and collapse of evaporitic strata within the Upper Roan Subgroup could have occurred during this period. Glacial and post-glacial conditions thought to be associated with the Grand

Conglomerate Formation (Binda and Van Eden, 1972; Wendorff and Key, 2009; Bull et al., 2011) may also have triggered dissolution and collapse. Replacement of gypsum and collapse breccia by carbonate and albite could have occurred via alteration by dissolution brines from a period encompassing Upper

Roan Subgroup time through deposition of Nguba Group sediments. Formation of the breccias had occurred by the beginning of the Lufilian inversion at approximately 590 Ma as they are folded and locally sheared by this deformational event.

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The stratigraphic partitioning of dominantly potassic alteration below the evaporitic sequences and breccia of the Upper Roan Subgroup breccia, and sodic-potassic alteration within and above these sequences (Selley et al., 2005), coupled with the dissolution versus residual brine signatures in ore deposits above and below breccia, indicates a fundamental change in basin hydrology associated with the

Upper Roan sequences and particularly the breccias. The Roan section appears to have produced two types of brine relatively early in the evolution of the ZCB, firstly residual brines associated with the deposition of evaporites and subsequently dissolution brines associated with dissolution of halite and/or non-marine Na evaporite. Ore deposits hosted in the Lower Roan Subgroup below the level of evaporite appear to have formed mainly from residual brine that sank into the lower part of the basin fill and the upper basement, producing widespread potassic alteration. Dissolution brine appears to have been produced prior to or during deposition of the lower Nguba Grand Conglomerate and Kakontwe

Formations. The Kipushi deposit in the CCB is located at this stratigraphic level and has a well-defined halite dissolution signature, consistent with its position adjacent a diapiric megabreccia. A sample of breccia from the Kolwezi megabreccia also shows a halite dissolution signature. These data are consistent with halite deposition in a basin-central marine setting, followed by halokinetic emplacement of megabreccia.

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CHAPTER 5

GEOLOGY AND COBALT-COPPER DEPOSITS OF THE TILWEZEMBE ANTICLINE

The Central African Copperbelt (CACB) contains a diversity of deposit types unparalleled in sedimentary copper provinces (Hitzman et al., 2012). The Congolese Copperbelt (CCB) portion of the province in the Democratic Republic of Congo (DRC) is best known for Cu-Co deposits hosted in disrupted, allochthonous blocks (“écailles”) within “megabreccia” (Demesmaeker et al., 1963; François,

1973, 1974, 2006; Cailteux, 1994; Cailteux et al., 2005; Hitzman et al., 2012; Schuh et al., 2012), but also contains distinct but incompletely understood metallogenic variations and local trends (Figure 5.1; Unrug,

1988; François, 2006; Hitzman et al., 2012). This paper provides observations on a distinct metallogenic sub-district in the western CCB with several newly discovered and/or developed deposits.

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Figure 5.1: Simplified geological map of the Congolese Copperbelt showing the location of deposits in the Tilwezembe anticline, and other selected deposits. Note the presence of distinct metallogenic trends or sub-districts. Modified after Hitzman et al. (2012).

132

5.1 Regional geology

The deposits of the CCB are hosted in rocks of the Neoproterozoic Katangan Supergroup,

subdivided into the basal Roan Group with mixed siliciclastic, carbonate and evaporitic rocks and the

overlying Nguba and Kundelungu groups each with glaciogenic diamictite at its base (Cailteux et al.,

2005; Hitzman et al., 2012). The Roan Group in the CCB consists of four subgroups, the lower three of

which contain evaporitic sequences and occur within megabreccia (François, 1973; De Magnée and

François, 1988; Cailteux, 1994; Jackson et al., 2003; François, 2006). The oldest strata comprise

variably dolomitic and hematitic fine-grained siliciclastic rocks (R.A.T. Subgroup). Evaporitic

dolostones and mixed dolostone-siliciclastic rocks of the Mines Subgroup host the “classical” stratiform

Cu-Co deposits in DRC. The overlying Dipeta Subgroup contains similar but poorly mineralized rocks.

The contact with dolostone, siltstone, and shale of the younger Mwashya Subgroup is commonly marked

by breccia.

Structural complexity in the CCB generally is ascribed to thrust stacking of Katangan rocks during the ~590 – 560 Ma Lufilian orogeny (François, 1973; Cahen et al., 1984; Kampunzu and Cailteux,

1999; Porada and Berhorst, 2000). Salt tectonic models provide additional explanation for large allochthons, diapirs, megabreccia, and abrupt thickness changes in the Nguba Group (De Magnée and

François, 1988; Jackson et al., 2003; Selley et al., 2010). The main stage of allochthon emplacement occurred subsequent to deposition of upper Kundelungu strata (François, 1973, 2006; Jackson et al.,

2003), broadly coincident with the onset of Lufilian shortening.

Stratiform Cu-Co deposits of the CACB typically are hosted by the stratigraphically lowest

reduced (or formerly reduced) facies rocks above a basal sequence of hematitic siliciclastic rocks (e.g.

classical Mines Subgroup écailles and Zambian argillite- and arenite-hosted deposits; reduced-facies

diamictite of the Grand Conglomerate Formation, lower Nguba Group at the Kamoa deposit: Hitzman et

al., 2012 and references therein). Hypogene mineralization in the Mines Subgroup is generally

recognized to pre-date formation of the megabreccia (Demesmaeker et al., 1963; François, 1973, 2006;

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Unrug, 1988; Cailteux, 1994; Cailteux et al., 2005), with reduction a primary mechanism for ore

deposition (Hitzman et al., 2012).

5.2 Local geology

The Tilwezembe anticline lies approximately 30 km east-southeast of the Kolwezi district, and

hosts a number of recently discovered and/or developed Co-Cu deposits (Figure 5.1 and Figure 5.2). The

deposits occur in a variety of stratigraphic and structural settings over a strike length of ~36 km. In

aggregate they contain more than 10Mt of Cu metal (Table 5-1), which in many instances excludes as

yet un-reported or undelineated hypogene sulfide resources. The deposits as a group also contain almost

3Mt of Co and are unusual in that Co typically contributes a substantial or dominant portion of the

resource value. The metallogeny of these deposits is thus of interest not only for exploration in what

might have been considered a mature district, but more broadly for insights into the distribution of, and

controls on, ore throughout the CCB.

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Figure 5.2: Geological map of the Tilwezembe anticline area, showing locations of the deposits discussed in text. The Kisanfu deposits were discovered under alluvial cover. After François (1980).

134

Table 5-1: Estimated copper-cobalt resources of deposits in the Tilwezembe anticline. Tonnage Cu Co Cu Co Deposit (Mt) (%) (%) (Mt) (Mt) Reference Tilwezembe 23 1.80 0.6 0.41 0.14 SRK (2009) Deziwa 319 1.44 0.12 4.59 0.38 Zijin (2010) Mutanda 299.5 1.48 0.59 4.43 1.77 Golder Associates (2011) Kalumbwe 2.5 2.87 Cu + Co 0.07 Cu + Co François, pers. comm. (2009) Kisanfu 108 2.62 1.08 2.83 1.17 Freeport-McMoRan (2011)

The Tilwezembe anticline is one of a series of ~east-west trending anticlines and fault-related

“extrusions” exposing Roan Group strata, south and in the hangingwall of the Kamikongwa fault

(François, 1973, 1980). This fault is interpreted as a regional thrust or former salt glacier that during the

earliest “Kolwezian” phase of deformation emplaced a nearly complete section of Roan through

Kundelungu group rocks northwards to lie on upper Kundelungu Group (Ku2.1) strata (François, 1973,

1980, 2006; Kampunzu and Cailteux, 1999; Jackson et al., 2003). Sinistral strike-slip movement on

east-west anticlines and faults (“extrusions”) offset Kolwezian folds during the “Monwezian” phase of

deformation (Kampunzu and Cailteux, 1999). Prior to recent exploration successes, this area was not

known to contain significant deposits.

The structure of the Tilwezembe anticline changes from east to west, and with this occurs a

systematic change in deposit style. Its eastern-most segment consists of a ~12 km long by ~2 km wide

eye-shaped anticlinal core exposing megabreccia of R.A.T., Mines and Dipeta subgroup rocks. In the

central and eastern parts of this area, both the northern and the southern limbs of the anticline contain

intact sequences of lower (R4.1) and upper (R4.2) Mwashya Subgroup rocks, in stratigraphic contact

with diamictite of the overlying Grand Conglomérat Formation. The Kisanfu and Kalumbwe-Miunga

deposits occur in this area and are hosted in Mines Subgroup écailles. The deposits are reasonably

typical of the Mines Subgroup style (e.g. Cailteux, 1994; François, 2006; Hall et al., 2011): ore occurs in

reduced facies dolostones and siltstones of the classical lower and upper orebodies of the Mines

135

Subgroup above a redox boundary with stratigraphically underlying hematitic rocks of the R.A.T.

Subgroup. Both disseminated and vein-hosted sulfides, and oxides after sulfides, occur.

In the vicinity of the Kalumbwe-Miunga deposits the subcropping anticlinal core of Roan megabreccia narrows, and R4.1 strata are missing from the southern limb. Further westward the anticlinal hinge pinches completely at surface, such that megabreccia is absent and R4 strata are entirely missing from the southern limb of the anticline. Here, diamictite on the southern limb is in fault contact with rocks of the Mwashya Formation on the northern limb. This ~6 km segment juxtaposes two sequences of reduced strata and has no known deposits.

The next ~12 km anticlinal segment begins where rocks of the northern limb abruptly change strike, becoming oblique to the trend of the anticline such that rocks on the southern limb overlie hematitic siltstones of the Nguba Group (Ng1.3) across the faulted anticlinal hinge. The change in strike represents one of the folds interpreted as offset during Monwezian strike-slip deformation (Kampunzu and Cailteux, 1999), however the southern limb or continuation of the fold across the fault.

This segment hosts the Mutanda and Deziwa deposits in fault-disrupted segments of the southern flank of the anticline. Ore at the Mutanda deposit occurs primarily within fault blocks of stromatolitic dolomite, dolomitic argillites, black shale and local jaspilite and oolitic dolomite of the lower Mwashya

Formation, and locally within the Grand Conglomérat diamictite. Both veinlet- and disseminated-style copper and cobalt oxides and sulfides occur. Ore sulfides and oxides at the Deziwa deposit occur primarily in fractured and brecciated diamictite and grey siltstones belonging to either the Mwashya

Subgroup or lower Nguba Group. Copper-cobalt sulfides and quartz-carbonate gangue infill fractures, without any obvious vein-specific alteration. An écaille of Mines Subgroup strata lies within a small zone of megabreccia adjacent to the Deziwa deposit, but despite its proximity to the deposit is barren.

The westernmost ~12 km segment of the Tilwezembe anticline juxtaposes reduced facies diamictite of the Grand Conglomérat Formation and locally lower Mwashya Subgroup rocks of the southern limb with hematitic siltstones and sandstones of the Kundelungu Group (Ku 1.2) on the

136

northern limb. The Tilwezembe deposit is hosted primarily in reduced facies rocks of the Mwashya

Subgroup, as copper and cobalt oxides in weathered dolostones and veins in green argillite.

5.3 Discussion

The distribution of deposits along the Tilwezembe anticline appears to be controlled primarily by

the juxtaposition of reduced rocks against oxidized rocks. This occurs both in the classical, stratiform

setting of the R.A.T. – Mines Subgroup redox boundary (Kisanfu and Kalumbwe-Miunga deposits), but

also in the less orthodox setting provided by emplacement of reduced Mwashya and lower Nguba Group

rocks over hematitic Nguba or Kundeulungu group rocks (Mutanda, Deziwa, Tilwezembe deposits).

Deposits do not occur in reduced rocks of the southern limb where they are in fault contact with reduced

rocks of the northern limb. This suggests that mineralizing fluids for the structurally controlled deposits

were sourced from or through hematitic rocks of the Nguba and Kundelungu groups. Structurally created

redox boundaries in settings such as faulted anticlines may therefore provide new exploration

opportunities in areas previously deemed mature.

Mineralization associated with the structural superposition of reduced and oxidized rocks

probably occurred during formation and/or disruption of the anticline. Vein and coarse-grained

mineralization in the classical Mines Subgroup orebodies at Kisanfu and Kalumbwe-Miangu may also

have occurred at this time. Reasons for the lack of mineralization in the barren écaille at Deziwa are

unclear, but may be due to the loss of permeability and chemical reactivity associated with widespread

diagenetic alteration that occurred in Mines Subgroup rocks prior to their emplacement in megabreccia.

The unusual structural style of the Tilwezembe anticline, whereby the symmetrical and

undisturbed eastern segment passes laterally into western segments with non-folded (i.e. no change in

strike) southern limbs overlying discordantly folded strata on the northern limb, is common throughout

the CCB (c.f. maps in François, 1973, 1980, 2006; Kampunzu and Cailteux, 1999). These geometries are

difficult to reconcile with a two-stage Kolwezian and Monwezian model, because there is no evidence

that ~north-south folds were produced during the northward-directed Kolwezian event, to later be 137 truncated by the east-west Monwezian event. Given recognition of the role of evaporites in the evolution of the Katangan basin, such geometries may better be explained by halokinetic models for evolving evaporite and megabreccia-cored anticlines (e.g. Giles and Lawton, 2002).

The high Co tenors and Co:Cu ratios of deposits in the Tilwezembe anticline are regionally anomalous and suggest a fundamental local control. This is unlikely to be due to the structural style of the anticline, because unlike the metal signatures the Tilwezembe structure is not unique. There also are no apparent differences in the host rock compositions or types that would make them particularly favorable for Co-rich mineralization. A difference in source rock and hence fluid composition may provide the best explanation for the anomalous metal budget, which under a halokinetic model may reflect local derivation from ~subvertically underlying strata.

138

CHAPTER 6

CONCLUSIONS

The Central African Copperbelt is hosted in weakly to moderately metamorphosed and deformed

Neoproterozoic sedimentary rocks that were deposited in an evolving intracontinental rift basin. Early rift-stage continental coarse-grained siliciclastic sediments of the basal Roan Group were overlain by shallow water mixed carbonate, siliciclastic and evaporite sediments of the middle portion of the Roan

Group. Polylithic breccias marking the former presence of evaporite in the ZCB form lenticular stratiform bodies associated with the tops of shallowing-upwards evaporitic depositional sequences. Renewed rifting and basin deepening deposited open marine, commonly fine-grained siliciclastic sediments and in places mafic igneous intrusive and extrusive rocks of the Mwashya Subgroup. Widespread and commonly thick deposits of glacial/periglacial diamictite and overlying non-evaporitic marine carbonate and siliciclastic sediments of the Nguba Group covered the sediments of the Roan Group. Deposition of a second diamictite and non-evaporitic marine carbonate and siliciclastic sequence, the Kundelungu Group, preceded deformation and metamorphism during the Pan-African (~590 – 500 Ma) Lufilian orogeny.

From both an exploration and a research perspective it is important to understand which factors in the geological development of the basin contributed to producing the remarkable metal endowment of the

CACB.

This study highlights regional-scale aspects of the geological setting and basin evolution important for the understanding of and predictive exploration for sedimentary copper deposits in the

Katangan basin, and by analogy other basins. The ongoing development and refinement of a stratigraphic and basin evolutionary framework is key to continued exploration success. Within this framework, the stratigraphic position of redox boundaries and the position, type, and post-depositional evolution of evaporite sequences are critical elements in controlling the location, type, and post-formation modification of ore deposits.

139

The CACB and Katangan basin can be broadly divided into two settings within which sedimentary copper deposits occur (Figure 6.1). Basin-margin settings are proximal to basement rocks and lack evidence for the deposition and/or preservation through burial of significant thicknesses of halite. They contain stratiform breccias formed from the dissolution and replacement of evaporite, probably including non-marine sodic evaporite minerals, and contain autochthonous deposits. These areas

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Figure 6.1: Simplified geological map of the Central African Copperbelt, showing the distinction between basin-marginal, autochthonous deposits and basin-central, allochthonous deposits. See text for discussion.

include the ZCB, the North West Province in Zambia, and the Kamoa area. Deposits here are commonly positioned below the evaporitic strata, except in condensed sections where such strata are absent and

140 deposits occur within rocks of the Mwashya Subgroup and lower Nguba Group. In such cases lateral movement of brine is implied. In contrast, the CCB represents a basin-central setting characterized by lack of exposed basement rocks, and evidence for deposition and post-depositional preservation of sufficient halite to produce halokinetic structures, including diapiric and salt-canopy breccias. Most deposits in the CCB occur above the stratigraphically lowest evaporitic strata of the R.A.T. Subgroup, and consequently are allochthonous.

Evaporitic strata were therefore of fundamental importance both for production of salinity in ore fluid(s) and for their influence on the tectonic style of the basin and its deposits. The upper Lower Roan and Upper Roan subgroups in the ZCB and the R.A.T., Mines, and Dipeta subgroups in DRC constitute

“brine factories”, that generated residual brine through evaporative enrichment of seawater and subsequently dissolution brine through dissolution of Na-evaporites. Significantly, both basin-margin and basin-central settings contain deposits wherein ore sulfides have fluid inclusion solute compositions consistent with ore formation from residual rather than dissolution brines. This underscores the importance to mineralization of depositional and diagenetic processes that took place within and adjacent to evaporitic strata, and that pre-dated the brecciation and structural (halokinetic) emplacement of Mines

Subgroup orebodies in the DRC. The post-metamorphic structurally controlled Kipushi deposit represents the best-known example of a basin-central orebody formed by ore fluids derived partially from halite dissolution brine, within an interpreted halokinetic anticline.

Brine generated from evaporitic strata also produced alteration, which in the ZCB is stratigraphically partitioned into potassic-dominant alteration within the Lower Roan Subgroup and sodic- potassic alteration within the Upper Roan and Mwashya subgroups. This potassic versus sodic-potassic alteration zoning appears at least spatially linked to lower (Rokana Evaporites and Chambishi Dolomites members) and upper (Upper Roan Subgroup) evaporitic sequences, respectively. Both sequences contain anhydrite, but except on basement highs/horsts polylithic breccias are present only in the Upper Roan

Subgroup.

141

The prominence of sodic alteration within the Upper Roan and Mwashya subgroups and the indication of a non-marine Na evaporite dissolution signature in polylithic breccia and secondary dolomite in the Upper Roan Subgroup suggest that deposition of Na evaporite occurred primarily at this level in the ZCB. The lack of halokinetic features in the ZCB indicates either that depositional thicknesses of halite were minor (consistent with a non-marine signature) or that greater thicknesses were present but dissolved.

The evaporites of the Upper Roan Subgroup were deposited prior to a transition to open marine conditions, which is marked by non-evaporitic rocks of the Mwashya Subgroup or on structural highs by weakly evaporitic massive dolostones of the Kansuki Formation, Upper Roan Subgroup. Formation of breccia via dissolution and collapse of evaporitic strata probably commenced during this period and continued during glacial and post-glacial events associated with deposition of the Grand Conglomerate

Formation. The presence in the CCB of halokinetic structures discordantly emplaced into and above

~600m.y. old strata of the upper Kundulungu Group suggests evaporites in the CCB were preserved at least locally until the onset of the Lufilian orogeny. Dissolution of such evaporites could have contributed salinity to brines that formed post-metamorphic deposits such as Kansanshi and Kipushi. The relative timing and relationships of sedimentation, evaporite and brine formation, tectonic and halokinetic events, and mineralization are summarized in Figure 6.2.

An additional and fundamental factor in the siting of sedimentary copper deposits of the CACB is their ubiquitous occurrence within reduced or formerly reduced facies rocks. These facies encompass numerous lithologies at multiple stratigraphic levels and display a variety of types and textures of mineralization and alteration. An organizing principle underlying this complexity is the positioning of deposits at the stratigraphically lowest redox boundary within any given part of the Katangan basin. The

Kamoa deposit is an example of a major orebody within reduced facies diamictite of the lower Nguba

Group. The diamictite forms the lowest redox boundary within a condensed section on the western basin margin, whereas elsewhere in the CCB it is unproductive due to the presence of favorable host rocks at stratigraphically lower positions, primarily in the lower Mines Subgroup. Other deposits hosted in 142

Figure 6.2: Schematic representation of timing of sedimentation, production and mobilization of evaporite and brine, major basin events, and mineralization in the CACB.

reduced rocks of the Mwashya Subgroup and lower Nguba Group also occur in basin-marginal positions proximal to basement (e.g. Frontier, Sentinel: this study; Fishtie: Hendrickson, 2013). This relationship appears to be independent of the style of mineralization, which at Kamoa and Fishtie is primarily disseminated whereas Frontier and Sentinel are dominated by veins.

Macro-structural features such as major growth faults may allow ore fluids to bypass basal redox boundaries and mineralize stratigraphically higher reduced facies strata. The Kipushi deposit occurs in rocks of the lower Nguba Group in association with a bypass fault and an interpreted diapiric anticline. Deposits situated at structural redox boundaries such as occur in the Tilwezembe anticline may represent an example of bypass, and as such constitute a perhaps under-explored deposit style possibly linked to halokinesis. In broader terms major growth faults do appear to have been important in controlling fluid flow and localizing deposits, either directly or indirectly through influence on sedimentary and probably diagenetic facies. Evaporitic strata and breccia are thicker in the hangingwall of some growth faults in the ZCB and at Kamoa, a result of increased accommodation space.

The restriction of orebodies to strata broadly at or below the level of the Grand Conglomerate

Formation suggests it formed a hydrological seal (Unrug, 1988). In the CCB this formation commonly

143 reaches thicknesses of 0.5 to 1 km; such thicknesses of mud-matrix diamictite would be an effective barrier to vertical fluid flow and may also have provided a thermal seal. Bypass of this unit would allow mineralization to occur at higher stratigraphic levels, if favorable reduced strata were present. This could occur in structural settings such as the Tilwezembe anticline, but could also occur in areas where the

Grand Conglomerate Formation is thin or absent. The prevalence in anticlines and diapirs in the CCB of orebodies hosted in rocks of the lower Mines Subgroup indicates both the rarity of this phenomenon and the pre-folding and pre-halokinetic timing of mineralization within these orebodies.

Ongoing work in the CACB should include formalization of stratigraphic correlation and nomenclature, re-evaluation of tectonic styles and stratigraphic sequences in the context of evaporite types and thicknesses, study and comparison of metallogenically distinct parts of the Katangan basin, fluid inclusion studies of breccia, evaporite sequences, ore sulfides and gangue to better constrain different types and origins of brine, and geochronology of mafic rocks, ore sulfides and gangue.

Comparisons with other Pan-African Neoproterozoic belts, in particular with regards the role of evaporites and the brines derived from them, also will aid in understanding critical elements of the sedimentary copper ore-forming system.

144

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Schmandt, D., Broughton, D., Hitzman, M.W., Plink-Bjorklund, P., Edwards, D., and Humphrey, J., 2013, The Kamoa copper deposit, Democratic Republic of Congo: Stratigraphy, diagenetic and hydrothermal alteration, and mineralization: Economic Geology, v. 108, p. 1301-1324.

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Schuh, W. Leveille, R., Fay, I. and North, R., 2012, Geology of the Tenke-Fungurme sediment-hosted stratabound copper-cobalt district, Democratic Republic of Congo: Society of Economic Geologists, Special Publication 16, p. 269-301.

Schwellnus, J.E.G., 1961, Bancroft, in Mendelsohn, F., (ed.), The geology of the Northern Rhodesian Copperbelt: London, Macdonald & Co. (Publishers) Ltd., p. 214–233.

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Sillitoe, R.H., Perelló, J., and García, A., 2010, Sulfide-bearing veinlets throughout the stratiform mineralization of the Central African Copperbelt: temporal and genetic implications: Economic Geology, v. 105, p. 1361-1368.

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APPENDIX A CENTRAL AFRICAN COPPER DEPOSITS Table A-1: Central African Copperbelt Deposits.

Production Aooroximate Dimensions ** Latitude/ Contained and Reserves Grade other Dominant sulfide Dominant Host Autochonous/ Deposit % Cu Dominant host unit (length x width x thickness) Reference Longitude Cu (Mt) (millions of metals mineralogy Lithology allochthonous (m) tons of ore)*

ZAMBIAN COPPERBELT Kitwe Fm., Lower Roan Chambishi (main and west) 28.047 / -12.659 3.1 123.9 2.55 0.12% Co chalcopyrite, bornite dolomitic siltstone Main: 1200 x 1500 x 15 Autochthonous Garlick, 1961b; Freeman, 1988; J. Woodhead, pers. comm., 2012 Subgroup

Mindola Clastics Fm., Winfield, 1961; Freeman, 1988; ZCCM archive, 1994;Metorex Ltd., Chibuluma (East and West) 28.106 / -12.824 1.6 36.4 4.26 0.19% Co chalcopyrite quartzite, arkose 550 x 230 x 7.5 Autochthonous Lower Roan Subgroup 2005, T. Williams, pers.comm., 2007

Kakontwe: 1000 x 280 x 25 dolomite, Fishtie (Kashime) 29.409 / -13.356 0.5 41 1.25 chalcocite Nguba Group Grand Conglomerat: Autochthonous D. Wood, pers. comm., 2012; M. Hendrickson, pers. comm., 2012 diamictite 1000 x 280 x 40 Frontier 28.473 / -12.732 2.1 182.1 1.16 chalcopyrite shale Mwashya Subgroup 2300 x 300 x 20 Autochthonous D. Wood, pers. comm., 2012

Kitwe Fm., Lower Roan KCM, 2002; Freeman, 1988; Richards et al., 1988b; Hitzman et al., Konkola-Musoshi 27.797 / -12.347 26.8 894 3 chalcopyrite, bornite dolomitic siltstone 16,000 x 4000 x 10 Autochthonous Subgroup 2005;Torremans et al., 2012, T. Williams, pers. comm., 2002 Kitwe Fm., Lower Roan Luanshya: Luanshya-Baluba group 28.330 / -13.093 10.1 406.5 2.66 Baluba: 0.15% Co chalcopyrite, bornite dolomitic schist Autochthonous Lee-Potter, 1961; Mendelsohn, 1961; Freeman, 1988; ZCCM, 1990 Subgroup 11,250 x 2400 x 7 Lonshi 28.941 / -13.178 1.5 42 3.6 chalcocite diamictite Nguba Group 1200 x 800 x 15 Autochthonous D. Wood, pers. comm., 2012 C orebody: Mufulira 28.241 / -12.528 10.5 332.1 3.15 chalcopyrite, bornite quartzite Lower Roan Subgroup Autochthonous Maree et al., 1961; Freeman, 1988; MCM, 2000; FQM, 2002 5500 x 1200 x 14 Nchanga Upper dolomitic schist, Nchanga-Chingola group 27.843 / -12.507 23.4 1082.5 2.16 chalcopyrite, bornite Lower Roan Subgroup 3700 x 800 x 30 Autochthonous McKinnon and Smit, 1961; KCM, 2002; Freeman, 1988 orebody: 0.48% Co quartzite Kitwe Fm., Lower Roan Nkana-Mindola group 28.195 / 12.834 15.3 612.7 2.5 0.13% Co chalcopyrite, bornite dolomitic siltstone 12,800 x 1800 x 15 Autochthonous Jordaan, 1961; Freeman, 1988; Coats et al., 2001 Subgroup Samba 27.833 / 12.717 0.3 50 0.5 chalcopyrite felsic schists Lufubu Schist 700 x 150 x 25 Autochthonous Wakefield, 1978; M. Hitzman pers. comm., 2012

CONGOLESE COPPERBELT chalcopyrite, bornite, Kakanda group 26.399 / -10.730 1.3 41.3 3.13 0.14% Co dolomite Mines Subgroup Allochthonous Coates et al., 2008; J. Woodhead, pers. comm., 2012 carrolite chalcopyrite, bornite, Kambove-Kamoya group 26.602 / -10.884 2.5 44.5 5.7 0.2% Co dolomite Mines Subgroup Allochthonous J. Woodhead, pers comm., 2012 carrolite chalcopyrite, bornite, Grand Conglomerate, Sept 2011 resource: Kamoa 25.256 / -10.751 21.8 810 2.69 diamictite Autochtonous The Northern Miner, Oct 29-Nov 4, 2012 chalcocite Nguba Group 17,000 x 9000 x 6 http://www.mmg.com/en/Our-Operations/Mining- Kinsevere group 26.602 / -10.884 1.6 41 3.84 0.25% Co chalcopyrite dolomite Mines Subgroup Allochthonous operations/Kinsevere.aspx; Dec, 2010 11% Zn, 1% Pb, chalcopyrite, bornite, Intiomale and Oosterbosch, 1974; Intiomale, 1983; DeMagne and Kipushi 27.237 / -11.760 4.4 68.9 6.3 dolomite Nguba Group 2000 x 700 x 20 Allochthonous 160 g/t Ag sphalerite Francois, 1988; D. Broughton pers. comm., 2012 chalcopyrite, bornite, Kisanfu 25.950 / -10.780 1.3 108 2.32 1.08% Co dolomite Mines Subgroup Allochthonous Freeport-McMoran Copper & Gold Inc., U.S. S.E.C. Form 10-K, 2011 carrolite chalcopyrite, bornite, Kolwezi district 25.412 / -10.718 32.5 726 4.48 0.33% Co dolomite Mines Subgroup Allochthonous J. Woodhead, pers comm., 2012 chalcocite, carrolite chalcopyrite, bornite, Luishia-Kasongwe group 27.009 / -11.173 1.8 62.9 2.82 0.09% Co dolomite Mines Subgroup Allochthonous J. Woodhead, pers comm., 2012 carrolite chalcopyrite, bornite, Luiswishi 27.438 / -11.517 0.5 12.4 4.32 0.95% Co dolomite Mines Subgroup Allochthonous J. Woodhead, pers comm., 2012 carrolite chalcopyrite, bornite, Tenke-Fungurume district 26.237 / -10.606 19.1 547 3.5 0.27% Co dolomite Mines Subgroup Allochthonous Hitzman et al., 2005; J. Woodhead, pers. comm., 2012 chalcocite, carrolite Kwatebala deposit (Tenke- chalcopyrite, bornite, Fungurume district) - 26.160 / -10.380 3.5 105 3.31 0.29% Co dolomite Mines Subgroup Allochthonous Freeport-McMoran Copper & Gold Inc., U.S. S.E.C. Form 10-K, 2011 chalcocite, carrolite included in above NORTH WEST PROVINCE Mwashya Subgroup, Nov 2012 resource: Kansanshi 26.428 / -12.093 3.3 261.4 1.25 0.17g/t Au chalcopyrite phyllite Autochtonous D. Wood, pers. comm., 2012 Nguba Group 7400 x 2500 x 300 Basment schist Lower Chimiwungu: 4000 x 3700 x 60 Lumwana group 25.814 / -12.235 7 1073.9 0.65 chalcopyrite schist Autochtonous Bernau, 2007; Bernau et al., 2007; M. Richards, pers. comm., 2012 Roan Subgroup Malundwe: 4000 x 1400 x 14 Sentinel 25.312 / -12.259 5.3 1047 0.51 chalcopyrite phyllite Mwashya Subgroup 8000 x 1000 x 120 Autochtonous D. Wood, pers. comm., 2012

* Additional production and resources figures for many of the deposits are included in Hitzman et al. (2005). ** Approximate dimensions not given for deposits hosted in blocks of Mines Subgroup rocks in the DRC (allochthonous) as geometries of the blocks is commonly highly complex.

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APPENDIX B PUBLISHER AND CO-AUTHOR PERMISSIONS

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January 2, 2014

David Broughton is herewith authorized to include the following two papers as chapters in his Ph.D. thesis at Colorado School of Mines:

Broughton and Rogers, 2010, “Discovery of the Kamoa copper deposit, Central African Copperbelt, D.R.C.”, p. 287-297 of Society of Economic Geologists, Special Publication 15.

Hitzman et al., 2012,“The Central African Copperbelt; Diverse stratigraphic, structural, and temporal settings in the world’s largest sedimentary copper district”, p. 487-514 of Society of Economic Geologists, Special Publication 16.

______

Brian G. Hoal Executive Director

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African Mining Consultants Limited 1564/5 Miseshi Road P.O.Box 20106, Kitwe, Zambia Fax: +260 212 211104 Tel: +260 212 211108 [email protected] www.amc-africa.com

2nd January 2014

Re: Ph.D. Publication Authorisation

Dear Sir / Madam,

As a co-author of the Broughton and Rogers (2010 SDSHU ³'iscovery of the Kamoa Copper Deposit, Central African Copperbelt, DRC´SXEOLVKHGE\WKHSociety of Economic Geologists on pages 287-297 of Special Publication 15, I hereby authorise David Broughton to include this paper as a chapter in his Ph.D. Thesis at Colorado School of Mines.

Thomas Rogers Director: Exploration Services

AFFILIATED C203$1,(6Ɣ*2/'(5$662&,$7(6Ɣ%/8+0%85721(1*,1((5,1*

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FIRST QUANTUM MINING AND OPERATIONS LIMITED

Company Registration No. 36100

______23/12/2013 David Wood Plot 3805 Zambia Road P.O. Box 230022 Ndola, Zambia Tel: +260 212 659000 Fax: +260 212 651553

RE: APPROVAL FOR USE OF PAPER IN PhD

To Whom it May Concern

David Broughton has my permission to use the below paper on which I am a co-author as material submitted for his PhD :

Murray W. Hitzman, David Broughton, David Selley, Jon Woodhead, David Wood, and Stuart Bull. 2013 ͞dŚĞĞŶƚƌĂůĨƌŝĐĂŶŽƉƉĞƌďĞůƚ͗ŝǀĞƌƐĞ^ƚƌĂƚŝŐƌĂƉŚŝĐ͕^ƚƌƵĐƚƵƌĂů͕ĂŶĚdĞŵƉŽƌĂů^ĞƚƚŝŶŐƐŝŶƚŚĞtŽƌůĚ͛Ɛ Largest Sedimentary Copper District͘͟ /n SEG Special Publication Number 16 Geology and Genesis of Major Copper Deposits and Districts of the World: A Tribute to Richard H. Sillitoe. pp 487-514.

Yours sincerely

David Wood

Principal Geologist - Zambia FIRST QUANTUM MINERALS E-mail [email protected] Mobile +260966990637 (Zambia) Office Plot 3805 Zambia Rd Industrial Area, Ndola

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Dear Sir or Madam,

As a co-author of the Hitzman et al. (2012) paper, “The Central African Copperbelt; Diverse stratigraphic, structural, and temporal settings in the world’s largest sedimentary copper district”, published by the Society of Economic Geologists on pages 487-514 of Special Publication 16, I hereby authorize David Broughton to include this paper as a chapter in his Ph.D. thesis at Colorado School of Mines.

Stuart Bull January 2, 2014

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APPENDIX C DRILL HOLE COLLAR LOCATIONS

Table C-1: Exploration drill hole collar locations. Area Drill hole UTM E UTM N

Chambishi SE RCB2 616895 8594543 Itawa IT25 680291 8566602 Itawa IT26 681072 8566846 Itawa IT27 681412 8570153 Itawa IT28 680096 8571201 Mwambashi B BN42 606302 8591911 Mwambashi B BN43 606110 8592112 Luansobe L62 623756 8625850 Luansobe L79 624407 8625201 Luansobe L80 624961 8624409 Luansobe L83 625051 8625710 Mufulira DH214 636550 8615090 Mufulira DH218 635410 8615510 Mufulira DH219 635700 8615400 Mufulira MW107 631772 8618452 Konkola KN3 584939 8641118 Konkola KN18 587656 8638056 Konkola KLB94 588105 8629540 Konkola KLB99 587751 8633190 Konkola KLB145 586705 8634963 Kawiri KW24 591475 8634700 Kawiri KW26 591475 8632120 Nkana West Limb WL73 623010 8582840 Kakosa KNG6 597700 8621230

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APPENDIX D CARBON AND OXYGEN ISOTOPES

Table D-1: Carbon and oxygen isotope results.

Depth Depth δ13C δ18O δ18O Sample ID Area Drill Hole Lithology Strat Plot (ft) (m) (‰ VPDB) (‰ PDB) (‰ SMOW)

C1 Konkola KN18 754.6 Ksp-dol-chl vn in Mw mid Mw -2.83 -14.37 16.09

C2 Konkola KN18 785.8 Ksp-dol-chl vn in Mw mid Mw -1.60 -14.71 15.74 C3 Konkola KLB145 104.1 Fe cal-(cpy) vn with gn chl selvedge in Mw mid Mw -1.46 -13.73 16.76 C4 Konkola KLB145 60.6 Fe cal -(cpy) nod/vn? With gn chl selvedge in Mw mid Mw -1.56 -15.09 15.35 C5 Itawa IT13 368.0 bleached dol zone with sph vnlts in Kakontwe Kak 2.85 -2.15 28.70 C6 Itawa IT13 368.5 grey unbleached dol in Kakontwe Kak 3.20 -1.18 29.70 C7 Nkana WL73 435.8 folded bdg pll dol-qtz-py-sph vnlt @ base of OS OS -6.50 -9.21 21.41 C8 Itawa IT11 338.3 bleached dol zone with sph vnlts in Kakontwe Kak 2.74 -2.89 27.93 C9 Nkana WL73 433.0 qtz-dol flooding/vn zone with minor py, sph near base of OS OS -6.96 -7.24 23.45 C10 Nkana WL73 408.0 qtz-cal-py nodules in dk gy slst (OS) OS -11.34 -10.76 19.82 C11 Nkana WL73 401.7 qtz-cal-py nodules in dk gy slst (OS) OS -11.34 -10.83 19.75 C12 Konkola KN18 1441.9 bdg-pll qtz-dol-cpy fibre vein in UOS UOS -0.26 -10.13 20.47 C13 Mufulira M-11 diss pblasts of dol in bn -min'd B sst Muf ABC -8.64 -15.95 14.47 C14 Konkola U/G Fe dol from C-D OS with bn OS -10.14 -13.96 16.52 C15 Mufulira L80 4097.1 sst with py Muf ABC -18.12 -16.07 14.34 C16 Mufulira L80 4101.7 mudseam - pa gy enterolitic dol intergrown w ylw-bn sph Muf ABC -20.54 -17.79 12.57 C17 Mufulira L80 4101.7 mudseam with py, sph- cg dol intergrown w brown sph Muf ABC -20.66 -17.25 13.13 C18 Mufulira L80 4101.7 mudseam - cg dol band w/o sph Muf ABC -20.89 -17.88 12.48 C19 Mufulira L80 4101.7 mudseam - pa gy enterolitic dol intergrown w ylw-bn sph Muf ABC -17.99 -18.64 11.65 C20 Mufulira L80 4104.3 dol in sst with py (DB131) Muf ABC -18.94 -17.05 13.33 C21 Mufulira L80 4105.1 gwke sst with py, sph (DB132) Muf ABC -21.10 -17.36 13.01 C22 Mufulira L80 4113.0 gwke sst with py, sph (DB133) Muf ABC -22.25 -16.25 14.16 C23 Mufulira L80 4130.0 gwke sst with py, sph (DB134) Muf ABC -9.40 -19.16 11.16 C24 Mufulira L80 4141.0 dol in "gwke" sst, dol zone, with py, ylw-bn sph (DB135) Muf ABC -22.17 -18.35 11.99 C25 Mufulira L80 4169.5 dol in fw sst w py (DB136) Muf ABC -14.08 -17.60 12.76 C26 Konkola KLB145 686.3 bdg-pll qtz-dol-cpy fibre vein in OS OS -14.63 -14.16 16.31 C27 Konkola KLB145 681.3 bleached halo adj bdg-pll qtz-dol-cpy fibre vein in OS OS -12.85 -14.41 16.05 C28 Konkola KLB145 681.3 bdg-pll qtz-dol-cpy fibre vein in OS (DWB63-65) OS -13.35 -14.50 15.97 C29 Konkola KLB145 683.5 bdg-pll non-Fe dol band w cpy in OS (DWB66, 67) OS -14.29 -14.48 15.99 C30 Konkola KLB145 684.5 bdg-pll qtz-dol-cpy fibre vein in OS (DWB66, 68) OS -14.84 -14.43 16.03 C31 Konkola KLB145 684.5 diss dol in bleached zn adj bdg-pll qtz-dol-cpy fibre vein in OS OS -14.48 -14.48 15.98 C32 Frontier LD6 72.8 dol-cpy vn bx in alt'd slst Lufua 0.83 -14.68 15.78 C33 Frontier LD6 113.1 Fe dol-cpy vn bx Lufua 1.57 -15.25 15.19 C34 Frontier LD6 162.5 cg dol-cpy vn bx Lufua 0.55 -14.67 15.79 C35 Konkola KN18 1443.5 folded dol-qtz-cpy beds in UOS UOS -0.08 -9.93 20.67 C36 Frontier LUF-3 creamy fg dol Kak 2.49 -8.75 21.89 C37 Frontier LUF-6 cg grey marble Kak 5.82 -7.73 22.94 C38 Mufulira DH214 4820.0 bleached dol zone around cpy band Muf UR -3.00 -9.78 20.83 C39 Mufulira DH214 4820.0 bleached dol nod/zone assoc w cp Muf UR -3.08 -10.05 20.55 C40 Mufulira DH214 4820.0 pale bedded dol Muf UR -2.57 -9.42 21.20 C41 Mufulira DH214 4823.0 dol-cpy vn bx Muf UR -2.02 -11.71 18.84 C42 Mufulira DH214 4823.0 pale bedded cg dol Muf UR -1.36 -9.83 20.78 C43 Mufulira DH214 4670.5 dol-cpy vn bx in gy dol Muf UR 0.80 -23.95 6.22 C44 Mufulira DH214 4670.5 gy dol host Muf UR -0.10 -9.47 21.15 C45 Mufulira DH214 4752.0 bdg-pll dol-cp vn in musc dol Muf UR -2.01 -11.47 19.08 C46 Mufulira DH214 4652.0 barren cg dol vnlt cutting bdg pll dol-cp vn Muf UR 0.08 -20.46 9.82 C47 Mufulira DH219 2040.2 fw sst w diss Fe dol Muf fw 30.91 C48 Mufulira DH219 2024.5 fw sst bleached zone adj qtz-anh vn; diss Fe dol Muf fw -2.82 -17.33 13.05 C49 Mufulira DH219 2017.5 mottled sst outside of bleached zones Muf fw 30.91 C50 Mufulira DH219 2015.8 dol-anh-gn chl vn Muf ABC -2.73 -17.21 13.17 C51 Mufulira DH219 1980.6 top of B qtzite w diss Fe dol, cpy-bn Muf ABC -8.75 -13.18 17.33 C52 Mufulira DH219 1977.7 Lwr Dol, msv fg Fe dol Muf ABC 3.19 -11.70 18.85 C53 Mufulira DH219 1880.0 msv dol (Fe) Muf hw 3.65 -12.35 18.18 168

Depth Depth δ13C δ18O δ18O Sample ID Area Drill Hole Lithology Strat Plot (ft) (m) (‰ VPDB) (‰ PDB) (‰ SMOW)

C54 Mufulira DH219 1864.5 msv fg dol (Fe) Muf hw 4.75 -10.22 20.37 C55 Mufulira DH219 1843.5 msv anh-dol-talc (musc) bx fw Muf UR 6.83 -6.57 24.14 C56 Mufulira DH219 1746.3 dol wth anh nodules and vns Muf UR 2.41 -8.90 21.74 C57 Mufulira DH219 1743.3 vcg dol-anh vn in grey UR dol Muf UR -1.23 -10.30 20.29 C58 Konkola KN18 1420.7 folded dol-phlog slst in UOS UOS 1.87 -7.93 22.73 C59 Konkola KN18 1439.3 bdg-pll dol-phlog band in UOS UOS -0.27 -9.57 21.05 C60 Konkola KN18 1441.9 hi angle dol-qtz-cp vein in UOS UOS 0.04 -10.21 20.38 C61 Konkola KN18 1444.7 folded dol-phlog slst with py in UOS UOS 0.04 -9.75 20.86 C62 Konkola KN18 1462.0 isocl folded slst cut by qtz-dol bx and dol-anh vns: bx UOS -1.92 -12.18 18.35 C63 Konkola KN18 1462.0 isocl folded slst cut by qtz-dol bx and dol-anh vns: vn UOS -1.88 -13.10 17.41 C64 Konkola KN18 127.3 massive dol upr Mw dol 1.49 -5.22 25.53 C65 Konkola KN18 172.3 massive dol upr Mw dol 1.77 -4.59 26.18 C66 Konkola KN18 198.7 cg white dol in massive dol upr Mw dol 2.23 -7.12 23.57 C67 Konkola KN18 198.7 massive dol upr Mw dol 2.46 -6.83 23.87 C68 Konkola KN18 213.5 creamy dol + 5% phlog bed in gy dolc slst? upr Mw dol 5.12 -6.00 24.73 C69 Konkola KN18 273.3 creamy fg dol beds with act upr Mw dol 0.68 -7.19 23.50 C70 Konkola KN18 273.3 massively bleached dol (trace MoS2) upr Mw dol 0.58 -6.99 23.70 C71 Konkola KN18 285.2 dolc slst and dol upr Mw dol 0.03 -4.09 26.70 C72 Konkola KN18 299.7 gy laminated dol upr Mw dol -0.40 -2.50 28.34 C73 Konkola KN18 334.8 dol upr Mw dol 1.83 -3.00 27.82 C74 Konkola KN18 580.5 msv dol w phlog mid Mw -2.56 -11.96 18.58 C75 Konkola KN18 582.8 msv dol mid Mw -2.99 -12.37 18.16 C76 Konkola KN18 587.0 dol intbdd w slst laminae mid Mw -3.13 -12.13 18.41 C77 Konkola KN18 591.6 phlog-act dol intbdd w slst mid Mw -3.41 -13.07 17.44 C78 Konkola KN18 643.0 bdg-pll qtz-phlog-dol vn in slst mid Mw -2.20 -15.12 15.32 C79 Konkola KN18 675.8 bdd dol-phlog-qtz and slst mid Mw -3.54 -15.15 15.29 C80 Konkola KN18 758.8 sst with Fe dol cement mid Mw -2.42 -14.94 15.51 C81 Konkola KN18 792.4 sst with Fe dol cement mid Mw -0.44 -14.34 16.13 C82 Konkola KN18 1015.0 msv gy dol UR 2.90 -7.38 23.30 C83 Konkola KN18 1049.7 irreg dol-qtz patches/nodules in gn slst, py rims UR 3.46 -27.27 2.80 C84 Konkola KN18 1060.9 semi-perv dol flooding with local vuggy nodules UR 3.42 -17.04 13.34 C85 Konkola KN18 1107.5 vcg vuggy dol nodules/bands UR 1.51 -16.25 14.15 C86 Konkola KN18 1112.1 small dol-qtz nodules in dolc slst UR 3.23 -10.69 19.89 C87 Konkola KN18 1117.3 dol nodules in Cr green dol UR 2.81 -11.26 19.31 C88 Konkola KN18 1132.6 msv dol-qtz flooding zone in dol UR 2.81 -11.75 18.79 C89 Konkola KN18 1140.4 high angle dol-qtz "dyke" connecting qtz-dol zones UR 3.54 -10.94 19.63 C90 Konkola KN18 1145.9 nodular/enterolithic dol w stylolites UR 3.20 -11.59 18.96 C91 Konkola KN18 1163.2 fibrous dol vein passes into nodular vuggy dol (zoned): grey dol in vn UR -0.91 -9.11 21.52 C92 Konkola KN18 1163.2 fibrous dol vein passes into nodular vuggy dol (zoned): grey dol UR 1.23 -9.57 21.05 C93 Konkola KN18 1163.2 fibrous dol vein passes into nodular vuggy dol (zoned): white dol in vn UR 2.52 -11.74 18.80 C94 Konkola KN18 1163.2 fibrous dol vein passes into nodular vuggy dol (zoned): white dol UR 2.60 -11.02 19.55 C95 Konkola KN18 1220.7 folded bdg-pll grey dol-cpy vnlt in gy dolc slst UR 1.96 -9.46 21.16 C96 Konkola KN18 1220.7 gy dolc slst UR 2.94 -9.36 21.26 C97 Konkola KN18 1227.6 gy dol with nod/bands + cpy-py UR 2.93 -9.13 21.49 C98 Konkola KN18 1227.6 dol nodules/bands with cpy-py in gy dol UR 2.38 -10.76 19.82 C99 Konkola KN18 1227.6 dol nodules/bands with cpy-py in gy dol UR 1.35 -11.79 18.75 C100 Konkola KN18 1228.5 fibrous dol-qtz-cpy-py vein in gy dolc slst UR 1.59 -12.50 18.02 C101 Luansobe L80 579.7 = cg dol vein in Kakontwe Kak 0.72 -6.85 23.85 C102 Luansobe L80 580.0 grey laminated Kakontwe dol Kak 0.64 -3.90 26.89 C103 Luansobe L80 676.0 dark grey Kakontwe Kak 0.77 -3.40 27.40 C104 Luansobe L80 678.0 dark grey Kakontwe Kak 0.69 -3.32 27.49 C105 Luansobe L80 780.0 diamictite GC 0.75 -4.25 26.52 C106 Luansobe L80 833.0 dark grey dolc slst upr Mw 3.32 -3.59 27.21 C107 Luansobe L80 990.0 pale dolomite upr Mw 2.92 -3.72 27.08 C108 Luansobe L80 1127.0 dark grey silty dol upr Mw 2.52 -3.82 26.97 C109 Luansobe L80 1202.0 dark grey dolc slst upr Mw 2.43 -6.37 24.34 C110 Luansobe L80 1219.5 pale grey dolomite upr Mw 3.56 -3.14 27.67 C111 Luansobe L80 1219.5 cg dol-cpy vn in grey dolomite upr Mw 3.38 -4.28 26.50 C112 Luansobe L80 1356.0 pale laminated dolc slst upr Mw -0.22 -5.83 24.90 C113 Luansobe L80 1876.0 med-dk grey dolc slst mid Mw 0.16 -11.26 19.30 C114 Luansobe L80 1925.0 pale fg laminated silty dolo mid Mw 0.88 -7.77 22.90 C115 Luansobe L80 1992.0 massive white dol with minor phlog lwr Mw dol 2.25 -8.17 22.49 C116 Luansobe L80 2078.0 pinkish massive dol lwr Mw dol 1.34 -4.95 25.80 C117 Luansobe L80 2154.0 pale greenish grey silty dol lwr Mw dol -1.87 -5.32 25.43 169

Depth Depth δ13C δ18O δ18O Sample ID Area Drill Hole Lithology Strat Plot (ft) (m) (‰ VPDB) (‰ PDB) (‰ SMOW)

C118 Luansobe L80 2194.5 pale greenish grey bedded dol lwr Mw dol 1.82 -11.42 19.13 C119 Luansobe L80 2212.5 pbx with pale dol-(anh?) Muf UR 2.67 -12.52 18.00 C120 Luansobe L80 2963.5 mg crystalline dol-(anh?) Muf UR 4.44 -19.90 10.39 C121 Luansobe L80 3259.0 bedded brown (wthd) slst & dol bx'd by dol Muf UR 6.70 -15.89 14.53 C122 Luansobe L80 3333.8 white crystalline mg-cg dol Muf UR 8.24 -5.96 24.76 C123 Luansobe L80 3428.0 white crystalline mg-cg dol bx'd green slst Muf UR 5.13 -28.08 1.96 C124 Luansobe L80 3545.5 patchy/nodular texture white dol & grey host rock Muf UR 7.95 -6.30 24.42 C125 Luansobe L80 3600.0 dirty grey-white dol with phlog Muf UR 7.89 -9.38 21.25 C126 Luansobe L80 3620.3 med grey massive slst with dol Muf UR 8.23 -6.10 24.62 C127 Luansobe L80 3687.0 med-dk grey dol with white dol nodules/patches Muf UR 8.65 -5.06 25.69 C128 Luansobe L80 3735.0 sandy dol Muf UR 5.17 -10.33 20.26 C129 Luansobe L80 3545.5 gy dol gdms Muf UR 7.19 -7.61 23.06 C130 Nkana WL73 301.3 Fe dol-altd pbx UR -2.57 -13.08 17.43 C131 Nkana WL73 345.7 fg-mg gy dol bx w slst clasts UR -2.76 -12.92 17.59 C132 Nkana WL73 354.8 fg-mg gy dol bx w slst clasts UR -0.75 -10.91 19.67 C133 Nkana WL73 436.8 dol or dolc slst @ base of OS OS -9.90 -11.53 19.02 C134 Mufulira DH219 1747.8 pbx-UR dol contact: msv gy Fe dol w qtz xtls Muf UR 2.20 -10.81 19.77 C135 Mufulira DH219 1747.8 pbx-UR dol contact: white Fe dol vn cutting gy dol Muf UR 1.86 -23.83 6.35 C136 Mufulira DH219 1747.8 pbx-UR dol contact: pbx dol mtx Muf UR 1.81 -19.65 10.66 C137 Mufulira DH219 1747.8 pbx-UR dol contact: gy dol clast in pbx Muf UR 2.07 -9.89 20.71 C138 Kawiri KW26 168.9 pk dol bands intbdd with gn slst mid Mw 1.00 -10.17 20.43 C139 Kawiri KW26 268.0 dol nodules, sulfide slightly wthd lwr Mw dol -6.80 -12.72 17.79 C140 Kawiri KW26 254.3 mg recryst lst w py, minor phlog lwr Mw dol -2.88 -9.10 21.53 C141 Kawiri KW26 327.2 dol bx (cg vuggy dol xtls stwk assoc'd w pbx) UR -0.09 -10.29 20.30 C142 Kawiri KW26 431.0 bdg pll dol-qtz fibre veinlets UR 3.15 -11.44 19.11 C143 Lubembe LLB18 127.2 pk dol bands intbdd with gn slst: grey area least wthd? mid Mw 0.48 -7.35 23.33 C144 Lubembe LLB18 127.2 pk dol bands intbdd with gn slst: grey area mid Mw 0.50 -7.82 22.85 C145 Lubembe LLB18 162.5 white dol with speckled phlog lwr Mw dol 1.83 -6.14 24.58 C146 Lubembe LLB18 197.8 recrystallized gy dol lwr Mw dol 1.48 -5.54 25.20 C147 Lubembe LLB18 314.2 base of UR marker dolc shale UR 4.34 -5.79 24.94 C148 Lubembe LLB18 336.0 UAQ w dol (qtz) nodule Muf hw -4.15 -8.25 22.41 C149 Chambishi RCB1A 511.8 pale grey slightly ferroan bedded dol (+minor py, phlog) lwr UR 0.14 -6.91 23.79 C150 Chambishi RCB1A 511.8 pale grey slightly ferroan bedded dol (+minor py, phlog) upr UR 0.19 -6.88 23.82 C151 Mokambo KS17 1609.0 stromatolitic Kakontwe grey dolomitic Kak 1.24 -2.73 28.10 C152 Mokambo KS17 1749.0 stromatolitic Kakontwe mottled grey dolomitic, alt'd? Kak -0.05 -8.73 21.91 C153 Mokambo KS17 1812.6 reddish cg dol - qtz bx in Kakontwe Kak 1.51 -7.12 23.57 C154 Mokambo KS17 4560.5 vuggy cg dol in pbx UR -0.75 -10.74 19.84 C155 Mokambo KS17 4560.5 vuggy cg dol in pbx UR -0.68 -7.23 23.45 C156 Mokambo KS17 4560.5 groundmass dolo in pbx UR 0.86 -14.54 15.92 C157 Mokambo KS17 4843.0 pbx w dol UR 3.89 -13.59 16.90 C158 Mokambo KS17 4878.5 pbx-sst contact: wkly Fe dol mtx in pbx UR 3.00 -18.80 11.53 C159 Mokambo KS17 4843.0 dol clast in pbx UR 4.02 -17.17 13.21 C160 Mokambo KS17 5660.0 dol flooding adj pbx UR 3.22 -13.37 17.13 C161 Mokambo KS17 5672.0 dol UR 3.99 -16.26 14.15 C162 Frontier LD6 81.3 cg dol-cpy bx/vn in alt'd slst upr Mw 1.56 -14.65 15.81 C163 Frontier LD6 141.6 dol-altd slst upr Mw 0.56 -12.37 18.16 C164 Frontier LD6 151.0 pale grey strongly Fe-dol'd slst w py upr Mw -4.32 -13.10 17.40 C165 Frontier LD6 140.0 bleached dolc halo adj cpy vnlt upr Mw 0.61 -12.38 18.14 C166 Frontier LD6 202.5 pk-tan altd diamictite, minor dol (lo priority) GC 1.48 -15.36 15.08 C167 Mufulira MW107 5539.5 diss mg Fe dol+anh in intbdd sandy phlog-dol, fw sst Muf fw 0.55 -18.53 11.81 C168 Mufulira MW107 5339.0 diss cg Fe dol in sst at top of fw sst (SO4) Muf fw -2.65 -18.06 12.30 C169 Mufulira MW107 5283.0 diss fg Fe dol in C sst Muf ABC -0.30 -17.72 12.64 C170 Mufulira MW107 5255.0 bedded Fe dol + slst (Lwr Dol or Int A/B) Muf ABC 4.61 -13.28 17.22 C171 Mufulira MW107 5204.5 wkly Fe dolc slst (Int A/B) Muf ABC 2.03 -14.71 15.75 C172 Mufulira MW107 5156.6 diss Fe dol in arg sst (A) Muf ABC 1.20 -16.00 14.42 C173 Mufulira MW107 5174.7 diss Fe dol in arg sst (A) Muf ABC 0.30 -15.97 14.44 C174 Mufulira MW107 5040.2 wkly Fe dolc slst/fg sst (LAQ) Muf hw 5.18 -14.40 16.07 C175 Mufulira MW107 4852.5 sandy dol at base of GQ Muf hw 3.85 -12.80 17.72 C176 Mufulira MW107 4726.0 pa gy wkly banded dolc/calc UR 7.56 -7.58 23.09 C177 Mufulira MW107 4461.0 pa gy/wh msv dol w minor phlog UR 6.29 -7.46 23.22 C178 Mufulira MW107 3828.0 pbx, wkly dolc UR 3.48 -9.70 20.91 C179 Mufulira MW107 3765.0 anh-bx'd dol UR 4.82 -7.13 23.56 C180 Mufulira MW107 3629.0 pbx with dol UR 3.67 -17.60 12.77 C181 Mufulira MW107 3608.0 anh-bx'd dol UR 5.11 -6.19 24.53 170

Depth Depth δ13C δ18O δ18O Sample ID Area Drill Hole Lithology Strat Plot (ft) (m) (‰ VPDB) (‰ PDB) (‰ SMOW)

C182 Mufulira MW107 3288.0 anh-Fe dol crackle bx UR -1.72 -12.43 18.10 C183 Lonshi LLD09 Kakontwe dolomite, mineralized bleached zone cg dol adj cc Kak 1.22 -5.46 25.29 C184 Lonshi LLD09 Kakontwe dolomite, mineralized bleached zone cg dol adj cc Kak 1.22 -5.34 25.40 C185 Lonshi LLD09 Kakontwe dolomite, med-dk grey strom zone Kak 1.06 -3.03 27.79 C186 Lonshi LLD09 Kakontwe dolomite, pale grey bleached zone adj cg dol Kak 1.09 -1.76 29.09 C187 Luansobe L93 943.4 dol-cal cemented sst adj gwke, <1% diss py, tr cpy? Muf ABC -14.84 -19.19 11.13 C188 Luansobe L93 935.2 dk gwke with cal(dol) cement, 1% diss py Muf ABC -15.25 -19.22 11.09 C189 Mufulira MH-20922 M-4 massive fg-mg dol with dissem cpy, bn (mudseam) Muf ABC -5.08 -14.70 15.76 C190 Mufulira MH-20926 M-13 sugary qtzose dol (Fe) with diss cpy, bn Muf ABC -0.99 -11.18 19.39 C191 Mufulira MH-17114 1240ml 56/57xc mudseam - white dol with phlog, unmineralized Muf ABC -6.13 -15.85 14.58 C192 Mufulira MH-17121 1240ml 56/57xc Lwr Dolomite 0.5m above top of B qtzite; cpy>bn Muf ABC 0.81 -10.53 20.05 C193 Konkola MH-20906 K-11 dol-phlog-cpy band in C/D OS OS -17.97 -14.75 15.70 C194 Konkola MH-20912 K-10 bedding-parallel dol-qtz-cpy vein with irreg margins in C/D OS OS -16.89 -14.96 15.49 C239 Itawa 1702.4 stromatolitic dolomite, bleached & slightly ferroan UR 2.22 -3.67 27.13 C240 Itawa IT25 1722.0 massive dol below qtz granule zone UR 5.27 -7.96 22.70 C241 Itawa IT25 1722.0 dol mtx in qtz granule zone UR 6.12 -6.21 24.50 C242 Itawa 1983.0 cg dol vein/injection (?) cutting bedded slst UR -0.41 -3.06 27.75 C243 Itawa IT28D1 3529.0 bx dyke w dol mtx UR 3.28 -18.77 11.56 C244 Itawa IT28D1 3529.0 bx dyke w dol mtx UR 3.17 -18.59 11.74 C245 Kansanshi K115 140.2 dark grey calcitic marble with diss po Nguba (LCS1) 1.68 -13.41 17.08 C246 Kansanshi K115 140.2 white dolomite (albitized?) with phlog, diss cpy, py Nguba (LCS1) -0.72 -14.28 16.19 C247 Kansanshi K322 249.3 calc-qtz-mt-cpy-(bn) vns (sampled) with tan altd halo GC -2.56 -13.76 16.72 Kak (base C248 Kansanshi K359 224.5 med grey calcitic marble LM) 4.78 -15.43 15.00 C249 Kansanshi K306 210.5 med grey calcitic marble Kak (UM2) 5.66 -4.54 26.23 Nguba C250 Kansanshi K318 106.4 altered phyllite with cg dol-cpy vn (sampled) (MMC1) -3.11 -17.31 13.07 Nguba C251 Kansanshi K318 106.4 altered phyllite or marble (sampled) - merges with cg dol-cpy vn (MMC1) -3.39 -16.48 13.93 C252 Kansanshi K343 214.8 vcg white dol -(cp) vein Kak (LM) -3.10 -18.06 12.30 C253 Kansanshi SM02 116.5 altd phyllite clasts in cg dol (py) mtx breccia -2.22 -14.24 16.23 C254 Kansanshi K265 162.5 Fe dol in altn halo adj vn MMC1 -2.18 -13.94 16.54 C255 Kansanshi K265 162.5 steep cg dol-py vn MMC1 -2.97 -15.56 14.87 C256 Kansanshi Pit KA-5 cg dolomitic marble UM -2.76 -17.41 12.97 C257 Kansanshi Pit KA-6 fg calcitic marble UM 1.36 -16.12 14.30 C258 Kansanshi K11 135.0 Fe dol altn halo w cpy, adj vn LCS1 -2.27 -16.18 14.24 C259 Kansanshi K11 135.0 cg dol in qtz-dol-cpy vn LCS1 -3.21 -16.86 13.52 C260 Kakosa KNG6 349.1 dol-cpy bed in dark grey/black slst OS -13.78 -15.22 15.22 C261 Kakosa KNG6 349.2 dol-cpy bed in dark grey/black slst OS -13.94 -15.48 14.95 C262 Nkana MH-17061 folded dk gy wkly carb phyllite & dol bands, cpy in fold noses OS -16.37 -13.51 16.98 C263 Nkana MH-17046 argillaceous ore: phlog phyllite with stwk of cal-cpy vnlts OS -14.65 -15.39 15.04 C264 Nkana MH-17047 folded barren cal-phlog beds in phyllite OS hw arg -11.76 -14.44 16.03 C265 Nkana MH-20962 dk grey carb shale ore with grey cal-qtz-cpy bands OS -13.67 -15.32 15.12 C266 Nkana MH-17062 dk gy carb phyllite with deformed fol-pll py-qtz-cal nodules OS -23.06 -13.19 17.31 C267 Luanshya grab dk phyllite with deformed fol-pll cpy-qtz-dol nodules OS -10.04 -10.72 19.86 KLB94 701 Konkola KLB94 701.1 213.5 Ng 2.1 4.62 -4.25 26.53 KLB94 801 Konkola KLB94 801.3 244.0 Ng 2.1 3.67 -3.06 27.76 KLB94 901 Konkola KLB94 901.5 274.5 Ng 2.1 1.71 -4.04 26.75 KLB94 1002 Konkola KLB94 1001.6 305.0 Ng 1.2.2 (Kakontwe) 0.65 -5.92 24.81 KLB94 1057 Konkola KLB94 1056.8 321.8 Ng 1.1 (Grand Cgl) -1.08 -5.77 24.96 KLB94 1172 Konkola KLB94 1172.1 356.9 Ng 1.1 (Grand Cgl) -1.05 -8.65 21.99 KLB94 1261 Konkola KLB94 1261.1 384.0 Mwashia 0.90 -8.05 22.61 NE112 450 Nchanga NE112 449.9 137.0 Ng 1.2.2 (Kakontwe) 1.56 -2.92 27.90 NE112 596 Nchanga NE112 596.1 181.5 Ng 1.2.2 (Kakontwe) 0.80 -2.28 28.56 NE112 683 Nchanga NE112 683.1 208.0 Ng 1.2.2 (Kakontwe) 0.10 -4.35 26.43 NE112 768 Nchanga NE112 768.5 234.0 Ng 1.2.2 (Kakontwe) -0.05 -4.51 26.26 NE112 907 Nchanga NE112 907.4 276.3 Ng 1.2.2 (Kakontwe) 0.09 -4.92 25.84 NE112 1049 Nchanga NE112 1049.3 319.5 Ng 1.2.2 (Kakontwe) 3.36 -6.72 23.98 NE112 1055 Nchanga NE112 1054.8 321.2 Ng 1.2.2 (Kakontwe) 2.21 -8.68 21.96 NE112 1155 Nchanga NE112 1155.0 351.7 Ng 1.2.2 (Kakontwe) 1.80 -7.66 23.01 NE112 1210 Nchanga NE112 1210.2 368.5 Ng 1.2.2 (Kakontwe) 1.26 -7.22 23.47 NE112 1262 Nchanga NE112 1262.4 384.4 Ng 1.2.2 (Kakontwe) 0.54 -11.28 19.28 NE112 1283 Nchanga NE112 1282.8 390.6 Ng 1.2.2 (Kakontwe) 0.43 -9.24 21.38 Konkola KN18 71 North KN18 233.2 71.0 Ng 1.2.2 (Kakontwe) -0.83 -7.55 23.13 KN18 71.6 Konkola KN18 235.1 71.6 Ng 1.1 (Grand Cgl) -0.43 -6.29 24.43 171

Depth Depth δ13C δ18O δ18O Sample ID Area Drill Hole Lithology Strat Plot (ft) (m) (‰ VPDB) (‰ PDB) (‰ SMOW) North Konkola KN18 82.15 North KN18 269.8 82.2 Mwashia 0.62 -4.36 26.42 Konkola KN18 127.25 North KN18 417.9 127.3 Mwashia 1.52 -5.47 25.27 Konkola KN18 166.3 North KN18 546.1 166.3 Mwashia 1.65 -4.96 25.80 Konkola KN18 180.1 North KN18 591.5 180.1 Mwashia 1.77 -5.40 25.35 Konkola KN18 274.8 North KN18 902.5 274.8 Mwashia 0.04 -6.29 24.43 Konkola KN18 327.95 North KN18 1077.0 328.0 Mwashia 1.06 -3.24 27.57 Konkola KN18 372.8 North KN18 1224.3 372.8 Mwashia 0.26 -4.15 26.63

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APPENDIX E CRUSH-LEACH ANALYSIS

This study used a one-of-a-kind ion chromatography (IC) system developed by the U.S. Geological Survey that is capable of determining 22 cation and anion (F-, Cl-, Br-, I-, NO3-, CO3-2, PO4-3, HS-, SO3-2, SO4-2, S2O3-2, and C1-C4 organic acids; Li+, Na+, NH4+, K+, Rb+, Cs+, Fe+2, Mg+2, Ca+2, Sr+2, and Ba+2) species at sub-nanogram concentrations in inclusion fluids extracted from very small mineral samples (100-400 mg.). The solute compositions of fluid inclusions from deposits in the Central African Copperbelt were determined using this bulk extraction ion chromatography method. This analytical method has advantages over conventional crush-leach methods because it allows the analyses of very small samples that are crushed (∼0.3 g), but not powdered, and only briefly leached with ultrapure water (conductance=18 megohms/cm) water. This procedure minimizes leaching of ions from the host minerals and newly generated surfaces areas that promote adsorption of charged species. Moreover, this method permits an evaluation of contributed contaminates by (1) a pre-crush analysis to evaluate leeching of from surfaces of host minerals, (2) an analysis immediately after the sample is crushed to determine ions released from fluid inclusions, and (3) a post-crush analysis to determine solutes from solid inclusions in and adsorbed on minerals. Analysis of aqueous standards have a precision of 2 to 3% and replicate analyses on the natural sphalerite reference samples (c.f. LDAS-1in Viets et al 1996; and an in-house sample COY1) are generally better than 10% of mean values.

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Table E-1: Crush-leach analysis results.

Cats/ Mg+Ca Mg+Ca Sample Location Mineral Na NH4 K Rb Mg Ca Sr Ba F Acet Cl Br NO3 CO3 SO4 PO4 S2O3 Cl/Br Na/Br Na/K Na2 Cl/Br3 Ans /Cl -SO4 NS137 cpy/ca Nkana South CPY/Car+-dol 1.670 0.134 0.106 0.000 0.106 0.206 0.000 0.000 0.000 0.000 1.000 0.005 0.030 0.000 1.005 0.000 0.000 0.832 208.780 348.621 0.313 -0.692 15.799 1.670 208.780 E1099BX14- polylithic bx Kolwezi, DRC Chalcocite 1.072 0.009 0.032 0.000 0.005 0.003 0.000 0.001 0.000 0.000 1.000 0.001 0.005 0.000 0.047 0.000 0.000 1.028 1033.026 1107.198 0.008 -0.039 33.623 1.072 1033.026 KYA219cpy Kamoya, DRC CPY 0.208 0.009 0.116 0.000 0.038 0.270 0.005 0.006 0.000 0.000 1.000 0.004 0.022 0.000 0.095 0.000 0.000 0.799 269.774 56.209 0.309 0.214 1.790 0.208 269.774 DH1747 219Dol - polylithic bx Mufulira DH219 Dolomite 2.095 0.078 0.253 0.001 0.209 0.111 0.003 0.015 0.000 0.000 1.000 0.001 0.000 0.000 0.274 0.002 0.000 2.002 1560.972 3269.946 0.320 0.046 8.261 2.095 1560.972 DWB36DOL d - polylithic bx Konkola, KN18 Dolomite 2.111 0.137 0.151 0.000 0.818 1.557 0.007 0.000 0.000 0.000 1.000 0.001 0.003 0.768 1.283 0.000 0.000 1.403 680.106 1435.430 2.375 1.092 13.927 2.111 680.106 WL73 354 - incipient bx Nkana WL Dolomite 4.444 0.127 0.726 0.000 2.300 2.685 0.000 0.003 0.000 0.000 1.000 0.003 0.012 7.816 1.394 0.005 0.002 0.785 360.440 1601.830 4.985 3.591 6.119 4.444 360.440 KN18 1163.3 - nodule Konkola Dolomite 0.710 0.006 0.109 0.000 0.262 0.292 0.003 0.001 0.000 0.000 1.000 0.003 0.001 0.916 0.052 0.000 0.000 0.661 382.876 271.808 0.554 0.502 6.488 0.710 382.876 Mindola dup Nkana Dolomite+anhy? 0.896 0.011 0.451 0.000 0.584 1.578 0.003 0.000 0.000 0.000 1.000 0.003 0.009 1.147 0.945 0.000 0.000 1.094 288.668 258.675 2.162 1.217 1.985 0.896 288.668 H3477dn Kisanfu Bornite 0.127 0.010 0.118 0.000 0.024 0.108 0.004 0.008 0.000 0.073 1.000 0.004 0.013 0.000 0.014 0.000 0.000 0.485 272.693 34.543 0.131 0.118 1.071 0.127 272.693 H3479dn Kisanfu Bornite 0.955 0.068 0.133 0.000 0.077 0.143 0.000 0.000 0.000 0.298 1.000 0.002 0.008 0.000 0.019 0.000 0.000 1.185 427.700 408.350 0.220 0.201 7.181 0.955 427.700 NS137 1281cpy/py Nkana South Py/CPY 0.754 0.035 0.153 0.000 0.021 0.575 0.001 0.002 0.001 0.000 1.000 0.002 0.001 0.000 0.590 0.000 0.000 0.979 630.813 475.476 0.596 0.005 4.927 0.754 630.813 NS137 1300.5 Nkana South CPY/Car 1.513 0.032 0.082 0.000 0.032 0.013 0.000 0.000 0.000 0.014 1.000 0.005 0.014 0.000 0.280 0.000 0.000 1.078 216.907 328.110 0.045 -0.235 18.391 1.513 216.907 DD030 221.56 mag Kisanfu, DRC Magnesite 0.255 0.053 0.820 0.000 9.999 7.774 0.022 0.003 0.000 0.000 1.000 0.004 0.338 28.557 0.186 0.007 0.004 0.624 282.897 72.234 17.773 17.587 0.311 0.255 282.897 KW26-440.4 dol - fibre vein Kawiri Dolomite 1.309 0.010 0.058 0.000 0.277 0.367 0.001 0.001 0.000 0.000 1.000 0.001 0.001 0.619 0.160 0.000 0.000 1.042 705.578 923.581 0.644 0.484 22.639 1.309 705.578 H3410 car Kisanfu Carrollite 0.236 0.007 0.239 0.000 0.034 0.122 0.004 0.007 0.000 0.000 1.000 0.004 0.015 0.102 0.000 0.000 0.000 0.668 285.590 67.372 0.156 0.156 0.986 0.236 285.590 Z- K112 cu Ss vein Qtz 113.0 Kansanshi Quartz 0.828 0.012 0.044 0.000 0.000 0.000 0.000 0.008 0.000 0.000 1.000 0.003 0.000 0.628 0.014 0.001 0.000 0.394 370.467 306.684 0.000 -0.014 18.726 0.828 370.467 Z- K104 cu Ss vein Qtz 126.4 Kansanshi Quartz 0.946 0.008 0.054 0.000 0.040 0.090 0.000 0.002 0.000 0.000 1.000 0.004 0.000 0.000 0.015 0.000 0.000 1.229 237.921 224.976 0.129 0.114 17.500 0.946 237.921 Z- Cu Ss 113.0mK112veinCpy Kansanshi CPY 0.734 0.100 0.065 0.000 0.077 0.401 0.000 0.000 0.021 0.000 1.000 0.001 0.000 0.000 0.870 0.000 0.000 0.672 768.322 563.823 0.479 -0.391 11.262 0.734 768.322 Z- Cu Ss 126.4m K104 cpy Kansanshi CPY 0.742 0.006 0.035 0.000 0.078 1.107 0.000 0.008 0.001 0.000 1.000 0.003 0.000 0.000 0.433 0.000 0.000 1.697 378.368 280.836 1.185 0.752 21.270 0.742 378.368 Z- K343 214.8m py Kansanshi Py 0.744 0.006 0.039 0.000 0.021 0.224 0.000 0.003 0.001 0.001 1.000 0.002 0.000 0.000 0.095 0.000 0.001 1.075 512.169 380.859 0.245 0.150 18.851 0.744 512.169 Z- Cu Ss K343 214.8m vein calcite Kansanshi Calcite 2.001 0.012 0.234 0.001 0.067 1.357 0.000 0.001 0.000 0.000 1.000 0.001 0.000 0.818 0.065 0.000 0.000 1.842 1138.049 2277.264 1.424 1.358 8.557 2.001 1138.049 Z- Cu Ss K112 113m vein calcite Kansanshi Calcite 0.721 0.008 0.061 0.000 0.089 0.576 0.000 0.011 0.000 0.000 1.000 0.002 0.000 1.126 0.031 0.000 0.000 0.646 444.932 320.795 0.665 0.634 11.792 0.721 444.932 Z- Cu Ss K104 126.4m vein calcite Kansanshi Calcite 0.577 0.004 0.051 0.000 0.088 0.090 0.000 0.001 0.000 0.000 1.000 0.003 0.000 0.316 0.006 0.006 0.000 0.601 341.395 196.821 0.178 0.173 11.311 0.577 341.395 PZ-Ba calcite Kupferschiefer Calcite 0.503 0.003 0.010 0.000 0.038 0.353 0.000 0.001 0.000 0.000 1.000 0.004 0.000 0.000 0.015 0.000 0.000 1.256 259.423 130.431 0.391 0.376 52.845 0.503 259.423 PZ-vein cpy Kupferscheifer CPY 0.458 0.003 0.009 0.000 0.027 0.331 0.000 0.001 0.000 0.000 1.000 0.005 0.000 0.000 0.061 0.000 0.003 1.050 219.894 100.693 0.358 0.297 48.300 0.458 219.894 PZ-vein Bornite Kupferschiefer Bornite 0.494 0.003 0.011 0.000 0.028 0.209 0.000 0.000 0.000 0.000 1.000 0.004 0.000 0.000 0.040 0.000 0.001 0.906 234.525 115.928 0.237 0.197 46.316 0.494 234.525 KN18-1227.6 - mineralized nodule Konkola Dolomite (+Cu) 1.969 0.015 0.121 0.000 0.571 0.599 0.001 0.011 0.000 0.000 1.000 0.001 0.002 3.162 0.507 0.000 0.000 0.536 857.144 1687.941 1.169 0.662 16.239 0.494 234.525

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