Transcript Mining methods - British Geological Survey

Aynak – a world-class sediment-hosted
stratiform copper deposit in Afghanistan
Antony Benham, Stan Coats, Fiona McEvoy
British Geological Survey
Kingsley Dunham Centre
Keyworth
Nottingham NG12 5GG
Tel 0115 936 3100
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Structure
Introduction
- Afghanistan and the BGS project
- Mineral potential of Afghanistan
The Aynak copper deposit
- Geology of the area
- Style of mineralisation
- Past mining/exploration activities
- Current and future activity
Summary
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Introduction to Afghanistan
Turbulent recent history
Since the fall of the
Taliban in 2001:
• Hamid Karzai elected
President
• Peaceful elections in
2004 and 2005
• Return to stability
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Mineral occurrences in Afghanistan
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The Kabul
Block
Thought to be a
terrane accreted to
margins of Laurasia
250 Ma
Hosts numerous
copper occurrences
and old workings
Location of the
Kabul Block
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Tectonic map of Afghanistan
Area shown in
next slide
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Geological map of Aynak
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Cross sections through Aynak
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Stratigraphic column at
Aynak
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Mineralisation at Aynak
Left: Bornite mineralisation within dolomite marble of
the Loy Khwar Formation.
1cm
Near right: Porphyroblastic
dolomite marble with
chalcopyrite.
Far right: Finely laminated
biotite-feldspar-quartz schist
with disseminations and
stringers of chalcopyrite.
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1cm
1cm
Central
Prospect,
Aynak
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Central
Prospect,
Aynak
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Other occurrences in
the Kabul Block
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Past exploration at Aynak
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•
Extensive and detailed exploration
by Soviet geologists between197476 and 1978-89 including:
• >150 boreholes
• 70 trenches
• 9 adits
• Surface geological and
geophysical surveying
•
Soviet “drill-indicated” resource
estimate of 240 Mt @ 2.3 % Cu,
however this does not conform to
Western classification standards.
Current work at Aynak
•The BGS have created a
database from exploration
boreholes
•All reports relating to Aynak
have been translated from
Russian to English
•A 3D model of Aynak has
been created in Vulcan
•Reports and borehole
database available on request
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Vulcan model of Aynak
•The Aynak model created in
Vulcan is primarily based on
borehole data but also
includes sections drawn by
Soviet geologists
Left: Section through the
western prospect at Aynak
looking east through the
steeply dipping anticline
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Vulcan model of Aynak
•The mineralised Loy Khwar
Formation is the dark green
unit 5
Left: Section through the
central prospect at Aynak
looking west through the
shallow dipping section of
the Aynak anticline
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Vulcan model of Aynak
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Vulcan model of Aynak
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Possible Mineral Deposit Model
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Summary
Main features of the Aynak deposit
• World-class stratabound ore deposit (240 Mt at 2.3 % Cu)
• Mineralisation hosted within dolomite marbles and
calcareous-biotite schists
• Mineralogy dominated by bornite, chalcopyrite
• Consists of two prospects, the shallow dipping Central
Prospect and the more steeply dipping Western Prospect
• Central Prospect amenable to open-pitting
• Other prospects close to Aynak include Darband and
Jawkhar suggest Aynak is part of a larger “copper belt”
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