the deep lead mines of ballarat. what does this image represent to you?
Post on 27-Mar-2015
216 Views
Preview:
TRANSCRIPT
TheThe Deep Lead MinesDeep Lead Minesof of
BALLARATBALLARAT
What does this image represent to you?
And this?
Section 500 million years ago
Under the sea
Map 500 million years ago
Flat layers of sand and mud on the sea floor
Section 490 – 450 million years ago
Squeezing and folding - mountain building
Section 450-350 million years ago
Section 350 – 65 million years ago
Erosion
Map 65 million years ago -
Hills of 500 million year old rocks
Flat plain
- drained by rivers
Section 65 – 3 million years
Lava flows
Lava flows
Vulcanism
Map 3 million years ago – west covered by lava
Today’s river system
Where is the ancient river system?
WHERE’S THE GOLD
• In the youngest river system (Yarrowee River etc)
• In the quartz veins in the oldest rocks (Whitehorse Range, Black Hill) and buried under the lava flows of Ballarat West
• Widely spread in the old plains gravels (Golden Point, Poverty Point, Newington Gravels)
• Highly concentrated in the ancient river beds
LEAD
Any mineral deposit formed by mechanical concentration
in the bed of a stream by water action
SHALLOW LEAD
Any lead that is:-
• Not buried by younger rocks (sediment or lava)
• The course of the lead can be determined by the present topography
DEEP LEAD
Any lead that is:-
• Buried by younger rocks (sediment or lava)
• The course of the lead cannot be determined by the present topography
NOTE. There is no qualification of depth
30 metres
90 metres
40 metres
60 metres
110 metres75 metres
95 metres
Can
adia
n L
ead
Inkerman Lead
Golden Point Lead
Eureka LeadCosmopolitan
Cosmopolitan
Band and Albion No 2
Section across the Ballarat goldfield
Golden Point Lead Canadian Lead
Lava flowsSovereign Hill
Yarrowee River
Consols Lode
Drainage Direction
Ballarat Leads – Regional Context
The Deep Lead Mines
of Ballarat
The Pleasant Street
Group of Mines
Section through typical deep lead
Drill holeGutter Drift
Basalt
Bedrock
Sketch Plan and Long Section of Typical Deep Lead Mine
Sketch Section across Lead Showing Mine Workings
Plan of Deep Lead Working Method
Timbering of Wash Dirt Drives
Bedrock
Challenges to Deep Lead Mining
• Much water – extensive pumping necessary
• Basalts very hard – required blasting
• Deep sinking to reach lead
• Lead direction varied unpredictably
• Unstable ground in the wash dirt
More Challenges
• Very long drives – ventilation often poor
• Very long drives – haulage issues
• Mines needed to be highly mechanised
• Large Capital Investment required
• Poor legislative environment
• Resource is finite, unlike quartz vein mining
Deep Lead Mining Issues
The Frontage Claim System
Advantages of Deep Lead Mining
• Gold concentration much higher per unit volume
• Wash Dirt required less processing than quartz ores to release the gold
top related