Aynak – a world-class sediment-hosted stratiform copper deposit in Afghanistan

Aynak – a world-class sediment-hosted stratiform copper deposit in Afghanistan

• Antony Benham, Stan Coats, Fiona McEvoy
• British Geological Survey

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

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

Mineral occurrences in Afghanistan

The Kabul Block

• Location of the Kabul Block

• Thought to be a terrane accreted to margins of Laurasia 250 Ma
• Hosts numerous copper occurrences and old workings

Tectonic map of Afghanistan

• Area shown in next slide

• Geological map of Aynak

• Cross sections through Aynak

• Stratigraphic column at Aynak

Mineralisation at Aynak

• Far right: Finely laminated biotite-feldspar-quartz schist with disseminations and stringers of chalcopyrite.

• Near right: Porphyroblastic dolomite marble with chalcopyrite.

• Left: Bornite mineralisation within dolomite marble of the Loy Khwar Formation.

• 1cm

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• Central Prospect, Aynak

• Central Prospect, Aynak

• Other occurrences in the Kabul Block

Past exploration at Aynak

• Extensive and detailed exploration by Soviet geologists between1974-76 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

• The Aynak model created in Vulcan is primarily based on borehole data but also includes sections drawn by Soviet geologists

• Vulcan model of Aynak

• Left: Section through the western prospect at Aynak looking east through the steeply dipping anticline

• Vulcan model of Aynak

• Left: Section through the central prospect at Aynak looking west through the shallow dipping section of the Aynak anticline

• The mineralised Loy Khwar Formation is the dark green unit 5

• Vulcan model of Aynak

• Vulcan model of Aynak

Possible Mineral Deposit Model

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”