granitoids and volcanic rocks that make the basement to the Central

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1 Proterozoic A-Type granitoids and volcanic rocks that make the basement to the Central African Copperbelt,, Zambia Alberto Lobo-Guerrero S. Geologist, M.Sc., Min.Ex, Ph.D. Operations Vice-President Bogotá, Colombia;

2 About the Speaker Geologist, Geosciences Department, Universidad Nacional de Colombia, Bogotá M.Sc. in Mineral Exploration Geology, Queen s University, Kingston, Ontario, Canada Outer Space Specialist, International Space University Strasbourg, France Ph.D. in Geology, Economic Geology Research Institute, University of the Witwatersrand, Johannesburg, South Africa Currently consultant in exploration and mining actitivies at, Bogotá, Colombia.

3 Proterozoic A-Type granitoids and volcanic rocks that make the basement to the Central African Copperbelt,, Zambia Alberto Lobo-Guerrero S. Geologist, M.Sc., Min.Ex, Ph.D. Operations Vice-President Bogotá, Colombia;

4 Take-home message 1 Zambian Copperbelt basement = several generations of Proterozoic A-type porphyritic rocks & associated volcanics 2 Most granitoids display rapakivi features 3 Plutonics & volcanics show similar age & chemistry 4 Clearly an anorogenic ring complex cluster -with 4 distinct overprinted Proterozoic ARCC events 5 Main rock types: granites, alkali granites, qtzmonzonites & gabbroids 6 Complex geological history, alteration, metamorphism 7 Possible relationships between basement rks, IOCG mnzn & sed-hosted Cu mnzn 8 Basement hosts hypogene Cu mnzn veins & disseminations 9 Tricky macroscopic correlation -due to similar rock suites from different ages

5 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction Location General geology Anorogenic character -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

6 Introduction 1 Zambian Copperbelt = one of t t world s most prolific Cu provinces, composed by series of A-Type plutonic rocks & their correlative meta-volcanics volcanics.

7 Zambia In southern Africa

8 Location of the Zambian Copperbelt

9 Copperbelt Generalized Geology

10 Basement rocks in Zambian Copperbelt

11 Introduction 2 Basement rocks in t environs of t Copperbelt & intrusives that cut Katangan sedimentary sequence are all anorogenic. Most granitoids display rapakivi features.

12 A-type character of Copperbelt basement granitoids (a few of the diagrams by Whalen et al, 1987) K2O/MgO 10 K2O + Na2O ,000*Ga/Al ,000*Ga/Al

13 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

14 Modified TAS diagram (After Middlemost, 1994)

15 TAS Diagram for Rocks in the 17 Basement, Zambian CuBelt, Africa (Data from Lobo-Guerrero, ) Curves of Sigma Index values Petrographic fields 15 Muliashi Porphyry Lufubu Schists 14 Chambishi Mine environs Mufulira Granite and other rocks 13 Schist of the Samba Cu deposit Nchanga Granite granitoids 12 Nchanga Mine other intrusives Na 2 O% + K 2 O% X-08 7 MN153 MN154 L X X X L-273 MN150 6 L1 SiO 2 % MN152 L L-1 67a X-10 X-1 1 L-1 50 L-1 61 KNS1 X-14 L-268 L-170 X-09 BN53/1 X-38 Ba4 Ba5 X-40 Muliashi-Lufubu X-41 Suite X-39 L2 P-28 P-29 L-17 L Ba6 NG2 X-02 X-01 L-151 L-077 L-1 54 L-075 L-076 L-166 NG6 NG3 NG5L-162 L-153 L-160 NG4 X-34a NN 75/1 Cham bish i Granite X-36 X-05 L-0 78 L-159 Ba3 Ba2 L-158 X-03 L-155 Ba1 L-1 57 X- 35 X-37 MN 149 Nchanga Granite Ba7 X-04 L-269 L X

16 Statistics of rock types (TAS), Copperbelt basement, Zambia

17 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

19 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement Nchanga Granite Post-Katanga Intrusions Muliashi Porphyry Lufubu Schists -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

20 Nchanga Granite Sedimentary-hosted Cu mnzn at t Nchanga Mine lies unconformably on top of t Nchanga Granite ring complex (877±11Ma). Chemistry of t complex spans fields of midalkaline to subalkaline rocks.

Nchanga Granite Parts of t pluton are made of high heat producing granites that probably maintained a long-lived circulation of hydrothermal fluids.

21 Nchanga Granite Parts of t pluton are made of high heat producing granites that probably maintained a long-lived circulation of hydrothermal fluids. T Nchanga Granite might have contributed to t origin of Cu in its environs. Evidence for more plutons of similar characteristics around Konkola & Musoshi mines. Typical Nchanga Granite inselberg

22 Post-Katanga Intrusions LOGEMIN S.A. Widely-varying mafic rocks & midalkaline granitic dikes occur in t Nchanga mine area (~765Ma) Part of them intersect t Copperbelt basement & were emplaced after Katangan sediment consolidation; in some cases, after Cu-Co mineralization.

23 Muliashi Porphyry Geochemically-distinct group of rocks ( Ma). Some portions display hydroth. altn and/or metamorphism. Granitoids from environs of Chambishi (~1983Ma) & Mufulira (~1994Ma) are geochemically akin to Muliashi Porphyry.

25 D

26 Simplified log of exploratory Konkola Deep Borehole, Zambia 874? Geological history, Konkola deep borehole

27 Lufubu Schists Metavolcanic rocks, collectively called Lufubu Schists ( Ma, including the ~1964 Ma Samba deposit schists) correlate geochemically & geochronologically w plutonic rocks in t Copperbelt basement. Intimately related.

28 Lufubu Schists

29 TAS Diagram for Rocks in the 17 Basement, Zambian CuBelt, Africa (Data from Lobo-Guerrero, ) Curves of Sigma Index values Petrographic fields 15 Muliashi Porphyry Lufubu Schists 14 Chambishi Mine environs Mufulira Granite and other rocks 13 Schist of the Samba Cu deposit Nchanga Granite granitoids 12 Nchanga Mine other intrusives Na 2 O% + K 2 O% X-08 7 MN153 MN154 L X X X L-273 MN150 6 L1 SiO 2 % MN152 L L-1 67a X-10 X-1 1 L-1 50 L-1 61 KNS1 X-14 L-268 L-170 X-09 BN53/1 X-38 Ba4 Ba5 X-40 Muliashi-Lufubu X-41 Suite X-39 L2 P-28 P-29 L-17 L Ba6 NG2 X-02 X-01 L-151 L-077 L-1 54 L-075 L-076 L-166 NG6 NG3 NG5L-162 L-153 L-160 NG4 X-34a NN 75/1 Cham bish i Granite X-36 X-05 L-0 78 L-159 Ba3 Ba2 L-158 X-03 L-155 Ba1 L-1 57 X- 35 X-37 MN 149 Nchanga Granite Ba7 X-04 L-269 L X

31 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

32 Hydrothermal Alteration LOGEMIN S.A. Intense sodic alteration & hematitization are evident in basement rocks. -Other alterations include K, Rb & Pr enrichment -Some rocks display Nb & Cu enrichment Unidentified regional metamorphism processes, that took place before emplacement of t Nchanga Granite, modified original rock chemistry.

33 Rocks from t Samba Cu deposit are geochemically very similar to Lufubu metavolcanics. They were subject to depletion in Na & K. Transformed quartzmonzonites into granodiorites

34 (DelaRoche et al, 1980)

36 X-39 X-36 L-168 GR AD Nchanga Granite X-37 L-162 L-173 L-172 X-34a L-151 Ba1 Ba2 L-157 X-02 X-01 Ba3 L-158 X-35 X-40 P-28 L-153 P-29 L-166 SQ X-09 L-160 MN149 L-155 SQ L-159 X-42 NN75/1 Chambishi Granite X-03 GD L-279 L-077 X-05 Ba7 MZQ L-078 X-04 Muliashi Muliashi -Lufubu Suite L-268 MN154 MN150 MN153 MN152 L-170 L-273 L-075 L-076 X-08 Ba6 X-41 TO Ba4Ba5 MZ MZDQ KNS1 X-38 L2 BN53/1 DQ MZGO X-07 L1 L-161 Gabbroids MgB Diagram (Debon & LeFort, 1994) Basement to Zambian Copperbelt X-11 X-10 B = Fe + Mg + Ti GO X-06 X-13 L-167a X-14 L-150 Mg/(Fe+Mg) L-163 X-12

37 600 Nchanga Granite cluster L151 NG5 NG3 NG4 Ba1 NG6 Ba3 L-279 X-05 0 Muliashi Porphyry trend Ba 4 X-34a X-12 X-40 L P-29 L-077 X-08 L-075 L-076 X-41 Ba6 500 L L-163 AB Diagram (After Dbon & LeFort, 1994) Copperbelt, Zambia; Lufilian Arc Granitoid Project X-38 X-01 L-150 X-14 L-167a X-07 X-13 X-06 B = Fe + Mg + Ti 300 X-11 X-10 L X KNS1 X-07 L1 BN53/1 X-38 L2 P-28 Ba4 Ba5 100 Ba6 X-41 L- 077 L-075 L-076 X-08 L-078 L-273 X-05 L-279 NN75/1 Chambishi MN153 Granite Muliashi- -Lufubu Suite L-159 X- 42 MN152 X-04 Ba7 L X-09 MN154 L-160 X- 03 MN150 MN149 L-155 L-268 P-28 L- 166 L X-40 X-39 P-29 X-01 Ba3 Nchanga Granite NG6X-02 Ba2 Ba1 NG3 NG4 NG2 NG5 L-173 L-151 L-162 X- 34a L-153 L- 172 X-34 L-154 X-36 X-35 X-37 L-157 L-168 L Q = Si/3-(K + Na + 2Ca/3)

38 250 X-07 L1 200 L2 X-38 KNS1 BN53/1 Ba5 Ba4 150 X-08 Ba6 L-078 X-04 X-41 L-075 L-076 X L X L-159 L X-09 Ba3 50 Ba2 Ba1 0 MN153 NN75/1 Chambishi Granite P-28 X-34a X-03 MN154 L-273 MN150 L-166 L-077 MN152 K/(Na + K) X- 01 Nchanga Granite X-36 MN149 P-29 NG5 L-151 L-153 L-162 X-34 X-02 L-160 Muliashi porphyry trend NG4 NG3 NG6 L-154 X-35 X-37 L-173 L-172 X-39 L-155 L- 268 Ba7 L-269 NG2 L-158 X-40 L-157 L-168

39 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization Relationship basement rocks-iocg mnzn Association with sed-hosted Cu mnzn Hypogene Cu mnzn veins & dissemination -7 Macroscopic Correlation? -8 Conclusions

40 Relation to IOCG Near Chambishi, a large volume of anorogenic gabbroids intruded Katangan metasediments. Granophyres (nepheline syenite), an iron oxide body, and characteristic sodic±hematite alterations accompanied t gabbroids. These may be evidence for IOCG mnzn present below t Chambishi sedimentary-hosted Cu-Co deposit. Lots of other evidence

Millions of years ago 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 Copperbelt 2 Copperbelt 1 Witvlei At least 2

41 Millions of years ago Copperbelt 2 Copperbelt 1 Witvlei At least 2 known associations between anorogenic intrusions, sed-hosted Cu mnzn & IOCG mnzn in t Copperbelt

42 Hypogene Cu Some rocks from Muliashi Porphyry & associated metavolcanics (including hosts to Samba deposit) contain significant Cu (hypogene origin?) None of them bear resemblance w/ porphyry Cu systems.

43 Samba Cu deposit veins disseminations

44 Proterozoic A-Type granitoids & volcanic Copperbelt basement Contents -1 Introduction -2 TAS diagram -3 Event diagram -4 Main Units in Copperbelt basement -5 Hydrothermal alteration -6 Mineralization -7 Macroscopic Correlation? -8 Conclusions

45 Macroscopic Correlation? LOGEMIN S.A. Both Muliashi Porphyry & Mufulira suites contain pink + gray granitoids. T two suites are macroscopically & chemically identical. They seem to have formed -in similar environments -from equivalent protoliths but were emplaced 120Ma apart from each other.

46 Macroscopic Correlation? Muliashi Porphyry (Pink & Gray) Lufubu Schist

48 Congolese Granitoids Congolese granitoids of Luina & Mokambo domes have not been studied in great detail.

49 Take-home message 1 Zambian Copperbelt basement = several generations of Proterozoic A-type porphyritic rocks & associated volcanics 2 Most granitoids display rapakivi features 3 Plutonics & volcanics show similar age & chemistry 4 Clearly an anorogenic ring complex cluster -with 4 distinct overprinted Proterozoic ARCC events 5 Main rock types: granites, alkali granites, qtzmonzonites & gabbroids 6 Complex geological history, alteration, metamorphism 7 Possible relationships between basement rks, IOCG mnzn & sed-hosted Cu mnzn 8 Basement hosts hypogene Cu mnzn veins & disseminations 9 Tricky macroscopic correlation -due to similar rock suites from different ages

50 This entire presentation may be downloaded from webpage Thanks for your attention

51 Proterozoic A-Type granitoids and volcanic rocks that make the basement to the Central African Copperbelt,, Zambia Alberto Lobo-Guerrero S. Geologist, M.Sc., Min.Ex, Ph.D. Operations Vice-President Bogotá, Colombia;

SHORT TABLE OF CONTENTS

SHORT TABLE OF CONTENTS vii Abstract, v Short Table of Contents, vii Detailed Table of Contents, viii Aknowledgements, iii Conclusions, 395 1. Introduction, 1 2. Methodology, 4 3. Generalized Geology of