Taldybulak Exploration Licence, Kyrgyzstan
Geology of the Taldybulak deposit
At Taldybulak, an irregular shaped composite multiphase dacite stock with dimensions of 1,400 x 1,000m intrudes Ordovician andesitic volcaniclastics. Within the stock there is an abundance of large wall rock xenoliths, and the presence of pegmatite dykes in the wall rocks adjacent to intrusive contacts indicates that only the upper part of the intrusive body is currently exposed. The dacite stock is cut by a series of late- to post-mineral dykes of various compositions including: gabbro, lamprophyre, granite, felsic porphyry, pyroxene-diabase, syenites and diorite dykes. A complex of concentric granodiorite dykes surrounding the stock indicates that it is likely to be underlain by a substantial multi-stage intrusive body; the source for the porphyry-type mineralising fluids. Zones of mineralisation, a quartz-tourmaline breccia body and post-mineral dykes parallel the elongate East-West axis.
Mineralisation
The mineralisation forms an ellipse-shaped, east-west trending zone over an area of 1,100 by 600m centred on the stock. The mineralised zone appears to be strongly influenced by a number of structural directions and is interpreted as representing the upper part of a larger underlying porphyry-type mineralised body. The 2007 exploration drilling identified a previously unknown area of potassic alteration in the western part of Taldybulak Central, which substantially added volume to the above-mentioned NI 43-101 resource.
The mineralisation consists of 1 to 20mm thick quartz-stockwork veins with minor pyrite and chalcopyrite +/- molybdenite, generally associated with quartz-sericite alteration. Locally potassium feldspar alteration is associated with the quartz stockwork veins. Disseminated and veinlet sulphide mineralisation is only weakly developed in the host intrusives, however the adjacent volcanics are extensively mineralised by disseminated and veinlet sulphides, with or without quartz stockwork veining.
Historic mapping, geochemistry and geophysics has outlined a 4-5km zone striking East-South-East from Taldybulak to the Dzhangyztal prospect that hosts several occurrences of porphyry style mineralisation which have yet to be adequately tested. The similarity in the age, geological setting, alignment and clustering of porphyry-related mineralised bodies at Taldybulak with deposits such as Cadia (New South Wales, Australia) and Oyu Tolgoi (Mongolia), together with the encouraging intercepts on surface and in drill holes, indicates that Taldybulak is a favourable environment for the occurrence of a substantial Au-Cu resource. Cadia, operated by Newcrest Mining, contains at least six discrete orebodies, spread out over a 6km length, with an aggregate resource in excess of 31 million ounces of gold and 4.59 million tonnes of copper at similar grades to Taldybulak Talas.
Metallogenic zone
The Taldybulak-Talas licences are located within Talas-Kemin metallogenic zone, which is hosted by lower Palaeozoic island arc terrain. Lower Palaeozoic sedimentary formations are interlaid with units of the andesitic lavas, tuffs, and eruptive breccias and have been intruded by diorites, monzodiorites, granodiorites, and syenites. Deposit types and examples from the area include:
- Porphyry-copper-gold: Taldybulak-Talas, Andash, Uzunbulak
- Gold skarns: Aktash, Kanterek, Nason, Tokhtonnisai
- High sulphidation gold-silver: Taldybulak Levoberezhny, Tuyuk
Gold-rare earth elements and metals: Karadzhiga, Borubai, Kutesai-2