The Kumtor Gold Project is located 350 km
to the southeast of the Kyrgyz capital of Bishkek
and about 60 km to the north of the
international boundary with the People’s Republic of
China.
The deposit is perched at 4000 m on the western spur of the Tein-Shan Mountains,
part of the Tien Shan Metallogenic Belt which represents a major suture that
traverses Central Asia, from Uzbekistan in the west, through Tajikistan and the
Kyrgyz Republic, and into northwestern China. The metallogenic belt, a
Hercynian fault and thrust belt, spans more than 2,500 km and hosts a number of
mesothermal-type gold deposits including Muruntau, Zarmitan, Jilau, and Kumtor
- which is largest gold mine operated in Central Asia by a Western-based
company, having produced more than 8.6 Moz of gold between 1997 and 2011.
The
Kumtor gold Project comprises a Central Deposit, historically referred to as
the Central Pit or Kumtor Pit, and a series of smaller satellite deposits, the
Sarytor Deposit, Southwest Deposit and Northeast Deposit. At the end of 2012,
Kumtor’s proven and probable reserves totaled 93.1 million tones at 3.3 g/t
gold, 9.7 million contained ounces, with an open pit mining life to 2023 and
milling operations to 2026.
The
Tien Shan Metallogenic Belt is subdivided in to three main accretionary
elements, the North, Middle and South Tien Shan. The Nikolaev Fault separates
the North and Middle terrains while the South Tien Shan is separated from the Middle
by the Atbashi-Inylchek Fault. The Kumtor deposit is located in the northwestern
section of the middle Tien Shan, which is cored by granitic and granodioritic
intrusives assigned Meso- to Neoproterozoic ages. These intrusive have been
thrust over Proterozoic sedimentary and volcanic rocks, which in turn, are
thrust over younger Vendian-ages (youngest Proterozoic or oldest Palaeozoic)
clastic sedimentary rocks.
The
Kumtor deposit is classified as a structurally controlled meso-thermal gold
replacement deposit, opposed to a porphyry or epithermal system which are also
known within the Tien Shan Mineral Belt. The geology of the Kumtor deposit
comprises a series of major thrust and fault slices resultant from multiple
deformation events reactivating long-lived reverse faults. Mineralization is
associated with hydrothermal alteration of Vendian sediments, which took place
over four main pulses during the Permian. Pervasive
quartz-carbonate-albite-chlorite-sericite-pyrite alteration charaterises the
first pulse and deposited little gold. This first phase of alteration
strengthened the host rock permitting intense vein, stockwork and breccia
development during the following two pulses that deposited all of the
economically significant gold. Gold mineralisation of these main pulses formed
at temperatures of ~310 °C within veins, vinlets and breccia matrix, and covers
a strike length of more than 12 km. The gold and gold-bearing minerals occur as
fine inclusions within pyrite averaging sizes of only 10 microns.
Production
in 2011 was 18.12 t (0.583 Moz) of gold. Remaining ore reserves and mineral
resources at December 31, 2011 (Centerra Gold Inc., 2012) were: Proven +
probable reserves - 59.694 Mt @ 3.3 g/t Au; (reserves are in addition to
resources) Measured + indicated resources - 65.949 Mt @ 2.3 g/t Au; Inferred
resources - 9.195 Mt @ 2.4 g/t Au.
(Source: Kumtor
NI 43-101 2011 Technical report,
Porter
GeoConsultancy, www.portergeo.com.au , 2013)
