Geology and Cu-Ni-PGE Mineralization of Legris Lake Complex

Transcription

1 Geology and Cu-Ni-PGE Mineralization of Legris Lake Complex Neil Pettigrew and Keiko Hattori PLACER DOME Contents Regional geology Recent exploration History Geology of the Legris Lake Complex Characteristics of the Cu-Ni-PGE mineralization Comparison to other Cu-Ni-PGE deposits 1

2 Regional Geology Tib Lake Buck Lake Lac Des Illes Wabigoon ubprovince Upsala Lac Des Milles Lac 17 Demar Lake Legris Lake Rainy Lake 11 Atikokan Classical Quetico Intrusion Dog Lake 11 Fort Francis Rainy Lake amuels Lake tawson Lake Quetico ubprovince 11 hebandowan Lake 17 Redhornse Lake 17 Wawa ubprovince Canada U..A Thunder Bay Lake uperior Proterozoic Cover Archean Felsic Intrusive Rocks Alkaline Intrusive Rocks Ultramafic-Mafic Intrusive Rocks Metasediments Mafic and Felsic Volcanic Rocks Major Fault ubprovince Boundary Highway Tib Lake Gabbro Garden-Obonga Aeromagnetic Map Dog River Intrusion Lac des Iles Complex Lac des Iles Mine Legris Lake Complex Legris Lake Property Demars Lake Intrusion Wakinoo Lake Intrusion 2

3 LEGRI LAKE LAC DE ILE TIB LAKE 1.1 g Pd,.2 g Pt PDL LAC DE ILE REGION 527 Thunder Bay 527 Lake uperior HLM NA Palladium Lac des Iles Mine million tonnes 1.86 g/t Pd+Pt+Au 0 20 km BUC PDL FNX DOG RIVER INTRUION PGM Lac des Iles 3.92 g/t Pd+Pt+Au Legris L. BUCK LAKE 2.9 g Pd, 2 g Pt TAMAN LAKE PDL AVL/ OE PGM PGM diabase granite, gneiss ultramafic complex gabbro, norite, diorite sandstone, iron formation volcanics, iron formation highway, access road PGE deposit, occurrence WAKINOO LAKE 3 g Pt PDL DEMAR LAKE 2.6 g Pd,.3 g Pt MAPM/ EWR NC 2.83 g/t Pt+Pd+Au CGG 2.28 g/t Pt+Pd+Au 7.74 g/t Pt+Pd+Au AVL = Avalon Ventures Ltd. OE = tarcore Resources Ltd. BUC = Buck Lake Ventures Ltd. CGG = Canadian Golden Dragon Resources Ltd. EWR = East West Resource Corporation FNX = Fort Knox Gold Corporation HLM = Houston Lake Mining Inc. MAPM = Maple Minerals Inc. NC = New Claymore Resources Ltd. PGM = New Millenium Metals Corp. PDL = North American Palladium Ltd. Avalon/Placer/ tarcore Legris Lake JV kilometres Map compiled by Avalon Ventures Ltd. Accuracy is not guaranteed. Dec 2000 Recent Exploration History 154 km of line cut 136 km of ground based magnetometer surveys 88 km of I.P. surveys 97 km of grid mapping 945 prospecting samples collected 1500 m of diamond drilling Currently conducting 3 rd phase of trenching 3

4 Geology of the Legris Lake Complex Divided into four zones: Central Zone Eastern Border Zone outhwestern Border Zone Northwestern Border Zone Central Zone Well exposed Consists almost entirely of massive, homogenous 5ab leucogabbro Magnetic and I.P. surveys, however suggest much more complexity at depth 4

5 Main howing Trench Avalon Camp 2 Legris Lake 2 1 Poplar Zone Trenches I F I F 1 kilometre LEGEND 8 Diabase (Proterozoic) 5 Gabbroic 3 Ultramafic 7 Granitic Leucogabbro Clinopyroxenite 3a 6 Dioritic Main howing ubtype 5a* Wehrlite, Dunite 3b 3c 4 Igneous Breccia Biotite-rich ubtype 5ab 2 Metasedimentary Rocks Heterolithic Breccia Mesogabbro 5b 1 Metavolcanic Rocks Clinopyroxenite Breccia Melanogabbro 5c I F Iron Formation 5ab Leucogabbro 5

6 Eastern Border Zone Poorly exposed Comprises most leucogabbros, but also meso to melanogabbros and pyroxenites with minor breccia Contains large hanging wall metasediments tongues, extending up to 600 metres into the complex In contact with metasandstone and iron formation 6

7 Main howing Trench Avalon Camp 2 Legris Lake 2 1 Poplar Zone Trenches I F I F 1 kilometre LEGEND 8 Diabase (Proterozoic) 5 Gabbroic 3 Ultramafic 7 Granitic Leucogabbro Clinopyroxenite 3a 6 Dioritic Main howing ubtype 5a* Wehrlite, Dunite 3b 3c 4 Igneous Breccia Biotite-rich ubtype 5ab 2 Metasedimentary Rocks Heterolithic Breccia Mesogabbro 5b 1 Metavolcanic Rocks Clinopyroxenite Breccia Melanogabbro 5c I F Iron Formation outhwestern Border Zone Lacks abundant breccia Hosts the largest 5a* leucogabbro (main showing subtype) body yet discovered Hosts a zoned ultramafic dyke-like body with a dunite core containing semi-massive magnetite 7

8 Northwestern Border Zone Poorly exposed Experienced many phases of dioritic to pyroxenitic intrusions and multiple brecciations Consists mostly of heterolithic breccia Developed igneous layering in several phases Hosts all currently known Cu-Ni-PGE mineralization and the majority of the 5a* leucogabbro (main showing subtype) 8

9 Main howing Trench Avalon Camp 2 Legris Lake 2 1 Poplar Zone Trenches I F I F 1 kilometre LEGEND 8 Diabase (Proterozoic) 5 Gabbroic 3 Ultramafic 7 Granitic Leucogabbro Clinopyroxenite 3a 6 Dioritic Main howing ubtype 5a* Wehrlite, Dunite 3b 3c 4 Igneous Breccia Biotite-rich ubtype 5ab 2 Metasedimentary Rocks Heterolithic Breccia Mesogabbro 5b 1 Metavolcanic Rocks Clinopyroxenite Breccia Melanogabbro 5c I F Iron Formation Grid Map of Western Portion of the Legris Lake Complex 9

10 Heterolithic Breccia Clinopyroxenite Breccia 10

11 Igneous Layering in the Legris Lake Complex Cu-Ni-PGE Mineralization Occurrence and distribution Mineralogy Metal concentrations Mineralization models Comparison to other deposits 11

12 NA Palladium Lac des Iles mt 1.86 g/t PGE LEGRI LAKE HIGHLIGHT PDL AVL/OE 527 LEGRI LAKE PROPERTY 0.86 g/t m 1.62 g/t m 1.21 g/t 4.92 m Legris Lake Powder Hill Zone 0 5 kilometres NORTH AMERICAN PALLADIUM AVL/OE 3.16 g/t 9.95 m 1.11 g/t 0.77 m Legris Lake Complex diabase, granite, gneiss magnetic high Avalon 2000 drill hole Pd+Pt+Au core length 3.16 g/t 9.95 m 0 2 kilometres 5a* Leucogabbro (Main howing ubtype) 12

13 Cross ection of The Northwestern Border Zone 0.77m of 0.53g/t Rh 0.91g/t Pd 0.19g/t Pt 0.01% Cu, 0.07% Ni 10m of 3.16g/t PGEs 0.42% Cu, 0.13% Ni Main howing, 5a* Leucogabbro 13

14 Photomicrograph of Cu-Ni-PGE Mineralization Epd Pd Cpy Pd Millerite 14

15 High Rh, Low Cu, Leucogabbro emi-massive Magnetite Metal Concentrations frequency Pt/Pd ratio >100 ppb PGEs Ni (ppm) Cu vs Ni Pt/Pd ratio Cu (ppm) frequency Cu/Ni ratio >1 g/t PGEs Cu/Ni Total PGEs (ppb) Total PGEs vs Cu+Ni Cu + Ni (ppm) Pd vs Cu Au vs Pt+Pd Pd (ppb) Cu (ppm) Au (ppb) Pt+Pd (ppb) 15

16 PGE Concentration in a Fractionating ilicate Melt -Undersaturated -aturated Concentration of Element in ilicate Melt Ni Ir, Os, Ru Pd,, Cu Pt Pd, Cu, Crystalization Comparison to other Cu-Ni-PGE Deposits Very similar style of mineralization and geology to the Powder Hill and Vande Zones southwest of Legris Lake Complex imilarities to Lac des Iles and River Valley mafic-ultramafic complexes include: Rock Types Abundant igneous Breccias Cu-Pd-rich Cu-Ni-PGE mineralization 16

17 Lac des Iles Mine 145 million tones 1.86 g/t PGEs Poplar Zone 3.92 g/t PGEs tocker Zone 2.80 g/t PGEs Vande Zone 2.23 g/t PGEs tinger Zone 7.74 g/t PGEs Powder Hill Zone 2.83 g/t PGEs Powder Hill Zone Mineralized Leucogabbro 17

18 Pt/(Pt+Pd) vs Cu(Cu+Ni) Pt/(Pt+Pd) Komatiite-hosted Deposits Tholeiitic-hosted Deposits udbury Quetico Intrusions Coldw ell Rathbun Lake 0.1 Lac des Iles Cu/(Cu+Ni) Pt+Pd+Au >1000ppb Pt+Pd+Au <1000ppb, >100ppb Modified after Naldrett and Cabri 1976, Michaud 1998, MacTavish ummary 1 The Legris Lake Complex is comprised mostly of 5ab leucogabbro and appears to be at a shallow level of erosion The northwestern border zone is characterized by numerous gabbroic intrusive and brecciation events The system, however, remained stable enough between brecciations to allow crystal fractionation to occur producing igneous layering in several phases 18

19 ummary 2 The Legris Lake mineralization is Cu and Pd-rich and occurs in coarse grained 5a* leucogabbro bodies with melanogabbro to clinopyroxenite bases A second style of Rh-rich and Cu-poor mineralization occurs The Cu-Ni-PGE mineralization is very similar to the Vande and Powder Hill zones to the southwest The geology of the Legris Lake Complex also bears similarities to the Lac des Iles and River Valley mafic-ultramafic complexes 19