Toronto Geological Discussion Group
Geology and Mineralization of the New Afton alkalic porphyry Cu-Au deposit
The New Afton copper-gold mine is located near the city of Kamloops, British Columbia approximately 350 kilometres northeast of Vancouver. It is an underground block cave operation with new concentrator and tailings facilities situated adjacent to the historic Afton open pit which was operated by Teck between 1978 and 1997. As it is currently defined by drilling, the New Afton deposit extends along a southwesterly plunge for approximately 1.5 km from immediately beneath the Afton Mine open pit. Underground mining at New Afton began in June 2012 and the operation achieved commercial production ahead of schedule in July 2012. In 2015 the underground operation produced 105,000 ounces of gold and 86 million pounds of copper.
The New Afton deposit is part of a larger alkalic copper-gold porphyry district within the Iron Mask batholith complex of the Quesnel Trough island-arc terrane. Regional scale fault zones act as the principal controls to the emplacement of the intrusions and related porphyry-style mineralization in the area. The New Afton deposit itself is localized in an dilatational fault jog, formed during regional sinistral transpression during the early Juassic. Mineralization is characterized by copper sulphide veinlets, clots and disseminations localized at the contact between altered porphyritic monzonites and volcanic country rocks belonging to the Triassic age Nicola Group sequence. Secondary chalcocite and native copper occur in the upper near-surface parts of the deposit, most of which was mined from the historic Afton open pit. Gold occurs as sub-micron grains associated with copper sulphides.
The current mine schedule plans for production through to the year 2023. Since the start of the commercial production in 2012, exploration at New Afton has successfully extended the mineral resource below the current B-Zone block cave reserve. This work has resulted in the development of the C-Zone mineral resource which is currently the focus of a feasibility study which indicates the potential to add 5 more years to New Afton’s overall mine life. The C-Zone resource remains open to further growth both laterally and down plunge to the west. Site exploration is ongoing.
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