GOLD MINERALISATION IN THE TASMAN FOLD BELT SYSTEM,

NORTHEASTERN QUEENSLAND, AUSTRALIA

G.S. Teale1, I.M.A. Vos2, F.P. Bierlein2

1 Teale & Associates Pty Ltd, PO Box 740, North Adelaide SA 5006, Australia2 pmd*CRC, School of Geosciences, Monash University, VIC 3800, Australia

GOLD MINERALISATION IN THE TASMAN FOLD BELT SYSTEM,

NORTHEASTERN QUEENSLAND, AUSTRALIA

G.S. Teale1, I.M.A. Vos2, F.P. Bierlein2

1 Teale & Associates Pty Ltd, PO Box 740, North Adelaide SA 5006, Australia2 pmd*CRC, School of Geosciences, Monash University, VIC 3800, Australia

pmd CRC

*

12

3

4

5

67

8

Queensland

New South WalesSouthAustralia

Tasmania

edge of Precambriancraton

Lachlan Orogen

Hodgkinson - Broken River

Fold Belt

ThomsonFold Belt

New England Orogen

Major Lode Gold Deposits

1. Charters Towers2. Ravenswood3. Gympie4. Hillgrove5. Hill End6. Walhalla7. Bendigo8. Ballarat9. Stawell10. Beaconsfield

10500km0

9

Victoria

Delamerian

Bierlein & Crowe (2000)

Tasminides in Eastern Australia

Major lode gold deposits

• Central Victorian Goldfields have produced 2500 tonnes of gold.

• Deposits occur in quartz-rich turbidites of Cambro-Ordovician (Bendigo-Ballarat Zone) to Early Devonian (Melbourne Zone) age.

• Metamorphic grade ranges from zeolite to greenschist facies.

• The role of carbonaceous sediments is possibly important but debated

• Gold mineralisation is metamorphic related (orogenic) and pre-dates intrusive activity by as much as 80Ma.

Central VictoriaCentral Victoria

N Townsville

Cairns

Charters Towers

InghamGreenvale

19° S19° S

Innisfail

Big Rush

0 100km

CamelCreek

146° E

146° E

Q ld

Location

CORAL SEA

Camel Creek Big Rush Area

North East Queensland

G Teale 2004118

• Production of approximately 3 tonnes of gold with little alluvial gold present.

• Deposits and prospects occur in a sequence that ranges from Ordovician to Carboniferous.

• Metamorphic grade ranges from sub-greenschist to greenschist.

• The role of carbonaceous sediments was important.

Broken River ProvinceBroken River Province

• Gold mineralisation is orogenic and pre-dates Permo-Carboniferous intrusive activity (eg mineralisation can be contact metamorphosed).

• Pyrite, arsenopyrite, stibnite and trace to rare gold, aurostibite, chalcopyrite, berthierite, tetrahedrite, boulangerite, galena and sphalerite.

• Dominant gangue phases in high grade “reefs” are quartz, carbonate and lesser white mica and chlorite.

115 G Teale 2004

“Camel Creek”Homestead

“Ryeburn”Homestead

“Kangaroo Hills”Homestead

Camel CreekMine

Mt Lyall

Mt Jimmy

Blue Gold

RedGold

Beatrice

AP GoldSpartanDead Horse

Golden Cup

Dora Creek

Jacko, JackoExtended

NCamel

Cre

ek

Camel Creek AreaNorth East Queensland

Reserve drilling at the Blue Gold prospect, Amanda Bel Goldfield, 1988

G Teale 2004

N

Black Bull

Pit M

CentralPit

SouthPit

4000 N

3000 N

2000 N

1000 N

10000

metres

Camel Creek AreaNorth East Queensland

Mining Zones

116

Melange in South Pit, Camel Creek Mine

Transposed and boudinaged greywacke beds in carbonaceous shales, Camel Creek Mine

RT 295

RT 217RT 188

RT 57GA68 GA48

1060 E1040 E480 RL

460 RL

440 RL

1080 E 1100 E

0 10m

3m @ 3.5g/t

8m @ 2.03 g/t

28m @ 2.9 g/t

2m @ 0.42 g/t

7m @ 0.57 g/t8m @ 7.5g/t

12m @ 24.5 g/t

3m @ 1.3 g/t

1m @ 2.5 g/t

Oreb odyOutl ine

Camel Creek MineCentral Pit

Section 1970N(looking grid north)

G Teale 2004117

Free gold associated with sphalerite in massive stibnite

0.12 mm

Gold developing after aurostibiteand enclosing quartz gangue

0.12 mm

Closer view of previous slide. Aurostibite is being replaced by gold + stibnite ± native antimony.

0.025 mm

Gold in textural equilibrium with stibnite. Stibnite adjacent to the gold grain contains 0.7% Au.

0.025 mm

• The simple two phase liquid-vapour nature of the inclusions and the absence of gaseous phases like carbon dioxide or methane suggest that water was the main fluid constituent.

• No evidence of boiling which could be related to ore deposition was recorded.

• Fluid salinities between 2 and 5 wt% NaCl equivalent.

• Homogenisation temperatures suggest minimum fluid trapping temperatures between 160ºC and 300ºC.

• The inclusions are typical of orogenic gold deposits (lower T end) and have similar salinities, pressures and compositions.

Fluid Inclusion StudyFluid Inclusion Study

Homogenisation T Amanda Bel Goldfield

0

2

4

6

8

10

12

14

16

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

Th (Deg C)

Freq

uenc

y Camel CreekGolden CupRed Gold

N Townsville

Cairns

Charters Towers

InghamGreenvale

19° S19° S

Innisfail

Big Rush

0 100km

CamelCreek

146° E

146° E

Q ld

Location

CORAL SEA

Camel Creek Big Rush Area

North East Queensland

G Teale 2004118

Central Pit area at Big Rush during a pit blast.

10 110 E 10 130 E10 120 E10 000 E

BR120

480 RL

0 10m

490 RL

470 RL

460 RL

BR51

OrebodyOutl ine

10m @ 0.93 g/t11m @ 1.07 g/t

21m @ 1.08 g/t

30m @ 1.51 g/t

26m @ 1.44 g/t

31m @ 1.73 g/t

25m @ 1.06 g/t

3m @0.5 g/t

2m @ 0.32 g/t

3m @0.74g/t

6m @ 1.04 g/t

6m @ 1.45 g/t39m @ 1.07g/t

Big Rush Mine SOUTH PIT

Section 10 500NG Teale 2004113

460RL Level plan showing high grade mineralisation

and enclosing arsenopyrite-rich halo

500 RL

400 RL

Final PitOutlineGrade Control

valuesgreater than 5g/t

0 50 m114

South North

2m @ 19.9g/t1m @ 15.8g/t

18m @ 11.3g/tincl. 4m @ 45g/t

15m @ 12.89g/tincl. 4m @ 44.1g/t

2m @ 10.9g/t

1m @ 17g/t32m @ 11.42g/t2m @ 8.9g/t

1m @ 32.9g/t

1m @ 18.8g/t

5m @ 11g/t

1.56m @7.57g/t

1m @ 33.5g/t

2m @6.64g/t

2m @ 6.22g/t

2m @5.14g/t

14m @ 5.96g/t

8m @ 22.08g/t

4m @ 12.95g/tincl. 1m @ 43.6g/t

11m @ 51.6g/tincl. 5m @ 106.7g/t

9m @ 6.48g/tincl. 1m @ 41.1g/t

1m @12.54g/t

Big Rush Mine Central Pit - Longitudinal Section

Intercepts > 1m @ 5g/t Au

G Teale 2004118

1. Presence of highly carbonaceous (including graphite), pyritic and calcareous shales.

2. Presence of “tuffaceous” sandstones intercalated with carbonaceous shales. These act as conduits for mineralising fluids.

3. Structural control on mineralisation of strong axial planar cleavage (020º-030º) developed in tight parasitic folds in black shales (axial planar reefs and veins, disrupted saddles) and/or open folds in greywacke/sandstone units (saddle reefs, 3-dimensional quartz-sulphide stockworks).

Controls on Mineralisation, Big Rush DepositControls on Mineralisation, Big Rush Deposit

4. Slightly oblique shears and fault structures cutting the main mineralised package.

5. Plunge variation of folds on the local scale in conjunction with a mild “warping” of the fold structure.

6. Intersection of subtle 110º structures with the main Big Rush trend appears to cause “blow-outs” in the mineralisation.

• Development of ankerite, sericite, quartz and arsenopyrite in carbonaceous shales.

• This alteration domain can contain 0.5ppm to 1ppmgold.

• Forms a significant proportion of oxidised heap leach ore.

• Arsenopyrite → scorodite (FeAsO4.2H2O) → hydrated iron oxides; gold released and is amenable to cyanide leaching.

Wallrock AlterationWallrock Alteration

• Wide range of chlorite and carbonate compositions from deposit to deposit and within each deposit.

• Gold generally contains ~10% Ag.

• Arsenopyrite can contain from below detection gold to 1.5% gold.

• Stibnite can contain up to 0.7% gold.

Mineral ChemistryMineral Chemistry

Any questions?