1 / 32

SOUTH AFRICA 2006

SOUTH AFRICA 2006. A LITHOSPHERIC EXPERIENCE. THE TEMPORAL DISTRIBUTION OF MINERAL DEPOSITS: A STRONG REFLECTION OF TECTONIC AND LITHOSPHERIC EVOLUTION. Onset of Modern-Style Plate Tectonics ?. 200. 100. 50. Gold Resource (Moz). 30. 10. 2.7. ~ 50%. 1.9.

lula
Download Presentation

SOUTH AFRICA 2006

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SOUTH AFRICA 2006 A LITHOSPHERIC EXPERIENCE

  2. THE TEMPORAL DISTRIBUTION OF MINERAL DEPOSITS: A STRONG REFLECTION OF TECTONIC AND LITHOSPHERIC EVOLUTION Onset of Modern-Style Plate Tectonics ? 200 100 50 Gold Resource (Moz) 30 10 2.7 ~ 50% 1.9 DAVID I GROVES, CET &TSRC, UWA with Richard Vielreicher, Richard Goldfarb, Kent Condie &Jon Hronsky Relative Crustal Growth ~ 25% 1.2 Ga 0 1 2 3 0.5

  3. Pink Terraces: Rotorua Champagne Pool: Rotorua OK Tedi: Papua-New Guinea OUTLINE OF TALK • Temporal Patterns of Mineral Deposits • Supercontinent Cycle • Formational Factors • Preservational Factors • Tectonic Evolution and Preservational Controls • Tectonic Evolution and Formational Controls • Conclusions

  4. GENERALIZED SECULAR TRENDS FOR MINERAL DEPOSITS Convergent Margins Intra-Cratonic to Continental Margins 3 Ga 2 Ga 1 Ga Ore type P Ore type P 3 Ga 2 Ga 1 Ga Cyprus - type Sediment-hosted uranium S M Abitibi - type Kiruna - type H V IOCG Olympic Dam - type Kuroko Ilmenite - anorthosite s l Orogenic gold a t SEDEX Zn-Pb e m - e s Paleoplacer Lead-zinc in carbo- a b nates: Mississippi and placer gold d e Valley - type t s o h - y t r Porphyry copper n y Sediment-hosted e h m p copper r i o d P e Porphyry molybdenum S Adapted from Barley and Groves, 1992

  5. MINERAL DEPOSITS IN TERMS OF TECTONIC SETTINGS AND SUPER-CONTINENT CYCLE Diamonds MVT (Kimberlite) IRGD PGE in Layered Intrusion Palaeoplacer Au-U VHMS Unconformity/ SEDEX Sandstone U BIF/Mn Carbonate IOCG Epithermal Au-Ag Ni-Cu Sulphide Diamonds Porphyry Cu-Au (Lamproite) Orogenic Au Rift Passive TECTONIC Convergent Anorogenic (Trappes) Margin Margin ENVIRONMENT SUPERCONTINENT (?) Incipient Stable Continent Assembly Breakup Breakup Time (approximately 300 - 500 m.y.)

  6. Groves et al (EG100)

  7. CAUSES OF HETEROGENEOUS TEMPORAL DISTRIBUTION OF MINERAL DEPOSITS • Temporal changes in the • processes that produce • mineral deposits or the • physico-chemical nature of • the environments in which • they form • Preservation potential of the • tectonic environments in • which the deposits form in • terms of evolution of the • Earths lithospheric mantle • The two alternative factors • may be partly interlinked

  8. Ni (Mt) Volcanic/Subvolcanic Komatiite - associated 24 20 Mafic Intrusion - related 16 12 8 4 Ga 3 2 1 0 FORMATIONAL FACTORS: SIMILAR TECTONIC SETTINGS BUT HOTTER EARTH Nickel-Sulphide Deposits SpinifexTexture Kambalda Ore

  9. Mn (Mt) Manganese Deposits Largest reserves (not in production) 3500 2500 BIF (deep water) Black shale (shallow water) Oncolitic/oolitic (shallow water) Karst (continental) 1500 Main production from Oligocene 500 Age (Ga) 3 2 1 0 U3O8 (103 Mt) Uranium Deposits in Sedimentary Rocks 800 600 Quartz pebble conglomerate Unconformity type Breccia Sandstone roll-type Collapse breccia pipe Surficial 400 200 Age (Ga) 3 2 1 0 FORMATIONAL FACTORS: ENVIRONMENTAL CHANGES TO ATMOSPHERE-HYDROSPHERE SYSTEM

  10. MISSISSIPPI VALLEY TYPE (MVT) DEPOSIT Canning Basin, WA SEDIMENTARY- EXHALATIVE (SEDEX) DEPOSIT McArthur River, Queensland

  11. 1200 e t 500 50 a d t n Ore (Mt) a l S a b e a - v i a r t r a i e Metal (Mt) T d O N h M e M 300 30 o d u g n i A r c e o o k r e s r R E o 100 10 M 1 0 3 2 0.5 FORMATIONAL FACTORS: CHANGES TO BIOSPHERE MVT deposits ) s t ) 180 1200 s t l M a l M i ( P H ( l 150 1000 s SEDEX deposits a n d e t r e r e a k O 120 800 o w M l r l o n B a H a 90 v 600 g v s o a i i l r a D l u u L 60 400 e p d S c Jinding i e r d i R 30 a 200 C l a S 0 1 3 2 0.5 Age ( Age ( Ga Ga ) )

  12. A. PLATE-TECTONIC REGIME B. MANTLE OVERTURN EPISODE Large Igneous Province Arc MOR Arc Plume Head 660 km Plume Tail 2900 km PRESERVATIONAL FACTORS: MANTLE PLUME – INFLUENCED TECTONICS TO PLATE TECTONICS Schematic diagram showing contrasts between normal plate-tectonic regime and periods of mantle overturn and crustal growth (after Coffin, 2003)

  13. PRESERVATIONAL FACTORS: MANTLE PLUMES AND GROWTH OF CONTINENTAL CRUST Juvenile continental crust 14 2.7 Ga 12 Volumepercent 1.9 Ga 10 8 6 4 2 3.8 3.4 3.0 2.6 2.2 1.8 1.4 1.0 0.6 0.2 Height Mantle plume events (Abbott and Isley, 2002) Time (Ga)

  14. PRESERVATIONAL FACTORS: CHANGE IN NATURE OF SUBCONTINENTAL LITHOSPHERIC MANTLE O’Reilly (2003) Bouyant Archaean - Palaeoproterozoic – Negatively Bouyant Phanerozoic

  15. MODERN EPITHERMAL SYSTEMS Champagne Pool, Rotorua, New Zealand Hydrothermal precipitates with arsenic, tungsten and gold

  16. LOW PRESERVATIONAL POTENTIAL: PORPHYRY Cu-Au AND EPITHERMAL Au-Ag DEPOSITS Fish Lake McDonald Bingham Hishikari Cripple Creek Comstock Lode Round Mountain Pachuca-Real Del Monte Baguio Pueblo Viejo Pacific Ocean Santo Tomas II Grasberg Porgera Kelian Yanacocha Ladolam Batu Hijau Panguna OK Tedi Refugio Bajo De La Alumbrera El Indio Cadia Hill Waihi Subduction zone Gold-rich porphyry deposit Spreading ridge Epithermal gold deposit

  17. LOW PRESERVATIONAL POTENTIAL: PORPHYRY Cu-Au AND EPITHERMAL Au-Ag DEPOSITS > 350 Moz Au ) t M ) z ( o 250 250 Porphyry Cu-Au u M C Mostly circum- ( u 200 200 A Pacific deposits 150 150 100 100 50 50 ) 1 3 2 0.5 0 z o 150 M Epithermal Au-Ag ( u Mostly circum- 120 A Pacific deposits 90 60 30 1 3 2 0.5 0 ) z o M ( Orogenic Au u A 2 1 3 0.5 Continental crust growth curve 3 2 1 0.5 Age ( Ga )

  18. OROGENIC GOLD DEPOSITS

  19. Onset of Modern-Style Plate Tectonics ? TECTONIC EVOLUTION AND ROLE OF PRESERVATION IN SECULAR CHANGE: OROGENIC GOLD vs CRUSTAL FORMATION EVENTS 200 100 50 Gold Resource (Moz) 30 10 2.7 ~ 50% 1.9 Relative Crustal Growth ~ 25% 1.2 Ga 0 1 2 3 0.5

  20. TECTONIC RECONSTRUCTION OF RODINIA: EVIDENCE OF PHANEROZOIC-STYLE PLATE TECTONICS

  21. RARE OCCURRENCE OF 1 – 2MOZ OROGENIC GOLD DEPOSITS IN GREENSCHIST FACIES GREVILLIAN SUPRACRUSTAL BELT, BRAZIL

  22. BLACK SMOKERS PRODUCING VHMS DEPOSITS ON OCEAN FLOOR

  23. Mt (ore) ) n ) ) k o y 3000 l e g a F ) e i i g r b a a n C r i G m l C ( d F u ) l d ( s o y ) o l i l k d a a 2000 a K C ) o b r n g o ( r i o U r t h u i t W n u s i b k i i n i ( t M o T t i a i r ( H b o M B ( y i A 1000 R e n W k ( a r p W Tasmania a N u i a r T J (Mt Lyell) e b I 0 1 3 2 0.5 r 200 a o n ) Urals n i a z i r h h a e o d n c S 100 p C l i e r M u e a r l a n d t i i f a S s g ( a r o h 50 A k a l o i o L i S i n e r T t E t a Y e a c c s r n - i - f i B e e r a i n V a r h i a W u o i i r t e b s s e z o o n k u s A F a o s a 30 M u N t t m e l o r s a R r a - e r i e R A a r r e b l t n m e t o r n a a d b o a i e l K i l i b B H C S r o a d 10 r G a W A u S Q 0 1 3 2 0.5 Age ( Ga ) PRESERVATIONAL PATTERNS: VHMS vs OROGENIC GOLD DEPOSITS VHMS deposits Orogenic gold deposits

  24. Witwatersrand Ore Surface: Phillips and Law (2000) Nome Beach Placers: Goldfarb (2003)

  25. t (Au) Moz (Au) 3000 100,000 Witwatersrand 300 10,000 500 15 Tarkwa “Modern Placers” 400 300 200 Jacobina and Roraima 2 100 3.0 0.5 0 1.5 1.0 2.5 2.0 Age ( Ga ) PRESERVATIONAL PATTERNS: PALAEOPLACER AND PLACER GOLD DEPOSITS

  26. IRON OXIDE Cu – Au DEPOSITS Palabora Olympic Dam 200 m 1 km 1 km Igarape Bahia Mafic dykes Breccia / ore Sedimentary rock Carbonatites Volcanic rock Pegmatoid N Pyroxenite Breccia Granite / gneiss 1 km

  27. N ~ 100 km EXTENT OF BUSHVELD COMPLEX

  28. Normal Reef – Abnormal Geologist

  29. e c Age of diamond growth n a d ~ 0.1 Ga n u b ~ 3.8 Ga A e v i t a l e R 3 2 1 t n 14 e c r e 2.7 Ga 1.9 Ga p 12 e m u 10 l o V 8 6 4 2 3.8 3.4 3.0 2.6 1.8 1.0 0.6 0.2 2.2 1.4 TECTONIC AND LITHOSPHERIC EVOLUTION: FORMATION AND PRESERVATION Mt (ore) Carajas Province 2800 Olympic Dam 2000 Iron-oxide Cu-Au Palabora Lufilian Arc 1200 Candelaria 400 Khetri 3 2 1 50,000 PGE (kt) 8 Great Dyke PGE in layered intrusions 6 Bushveld Stillwater 4 Pana 2 1 3 2 Primary diamond Juvenile continental crust growth

  30. Fe-Oxide Cu-Au MOBILE BELT ANCIENT CRATON Olympic Dam MOBILE BELT Diamandiferous Lamproite Kimberlite Carajas ARCHAEAN CRUST Bushveld- Type PGE Palabora 50 LITHOSPHERE 100 Alkaline Intrusion 150 Metasomatized Mantle CARTOON OF ARCHAEAN LITHOSPHERE SHOWING Fe-OXIDE Cu-Au DEPOSITS AND OTHER MAGMA-RELATED DEPOSIT STYLES IN RELATED TECTONIC SETTINGS Metasomatized Mantle 200 ASTHENOSPHERE Depth in km PRESERVATION OF IRON-OXIDE Cu-Au, BUSHVELD-TYPE PGE AND DIAMOND DEPOSITS IN TERMS OF LITHOSPHERIC SETTING

  31. SUMMARY 1 • Most mineral deposits show distinctive temporal patterns • These patterns partly relate to factors such as: • position within supercontinent cycle • evolution of the atmosphere-hydrosphere-biosphere system • Most mineral deposits show mixed formational-preservational patterns due to: • progressive cooling of the Earth • change from plume-influenced/dominated tectonics to plate tectonics • decreasing buoyancy of subcontinental lithospheric mantle • depth of formation • In convergent margins, orogenic gold and VHMS deposits formed or were accreted throughout Earth history but show preservational patterns

  32. Iron-oxide Cu-Au, PGE and diamond deposits could only form after significant lithosphere formation : temporal patterns reflect depth of formation Palaeoplacer and placer gold deposits show a classic preservational pattern for near surface deposits Formational and preservational processes were coupled in the Archaean and Palaeoproterozoic but decoupled in the Mesoproterozoic to Present due to tectonic and lithospheric evolution SUMMARY 2

More Related