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The Shalkiya carbonate hosted lead-zinc deposit is located ~108 km NW of Kentau, and 780 km west of Almaty in southern Kazakhstan (#Location: 44° 0' 42"N, 67° 24' 39"E).
The deposit lies within the Neoproterozoic to Palaeozoic Karatau intracratonic rift basin, filled by sedimentary rocks, and intercalated lesser alkaline bimodal volcanic rocks.
The host rocks to ore are a 700 m thick sequence of Upper Devonian (Famennian) argillic carbonaceous dolomite, chert, cherty dolomite, dolomitic breccia and dolomitic limestone. These overlie a >800 m thick suite of Upper Devonian (Frasnian) variegated clastic sediments.
The basement to all of these rocks, commenced with a thick succession (6 to 7 km) of Meso- to Neoproterozoic clastic shale, carbonate and flysch sequences that were folded and intruded by granites. The unconformably overlying late Neoproterozoic commenced with a sub-aerial basalt-rhyolite and dacite-rhyolite red-rock volcanic series, followed by variegated continental and marine tuffs and clastic rocks with jasper and basalt, then sandstones and conglomerates with bands of dolomite. These are overlain by a few hundred metres of Cambrian and Ordovician siliceous-carbonate rocks, passing up into a thick succession (2 to 2.5 km) of flyschoid clastic rocks with andesite-basalt. During the late Ordovician and Silurian, these rocks were folded, with the intrusion of granitoids, to the Middle Devonian, when a stable platform had developed which was subsequently rifted to form the basin in which the mineralised carbonate sequence was deposited (Gorzhevskiy et al., 1989).
The hosts are overlain by ~2000 m of Upper Devonian to Lower Carboniferous (upper Famennian to Tournaisian) dolomite, limestone, mudstone, variegated sandstone and siltstone. The host sequence is cut by a 220 to 210 Ma lamprophyre dyke.
Gorzhevskiy et al. (1989) interpret the deposit to be the result of prolonged reaction between ore-bearing brines with Famennian to early Tournaisian carbonate rocks. They suggest that metals were leached from the basement shelf-rift sequences, transported as chlorides and organometallic compounds, and deposited at a carbonate geochemical barrier.
The principal sulphide minerals include sphalerite and galena, with marcasite, pyrite, arsenopyrite, boulangerite, bournonite and tetrahedrite in a gangue that includes anhydrite, dolomite, epidote, chlorite, fluorite and K-feldspar. The upper, oxidised zone contains goethite, hematite, cerussite, anglesite and other oxides.
Unattributed geological and mineralogical data is taken from the USGS Mineral Resources On-Line Spatial Database.
JORC compliant mineral resources and ore reserves in 2012 (Shalkiya Zinc website, 2013, after AMC Consultants [UK] Ltd), at a 3% ZnEq. cutoff, were:
Measured resource - 59 Mt @ 3.2% Zn, 1.0% Pb;
Indicated resource - 206 Mt @ 3.1% Zn, 0.7% Pb;
TOTAL measured + indicated resource - 265 Mt @ 3.1% Zn, 0.8% Pb, 2 g/t Ag;
Inferred resource - 9 Mt @ 4.6% Zn, 2.2% Pb;
Proved reserves - 44 Mt @ 3.3% Zn, 1.1% Pb;
Inferred reserves - 158 Mt @ 3.2% Zn, 0.8% Pb;
TOTAL proved + probable reserves - 202 Mt @ 3.2% Zn, 0.8% Pb
The most recent source geological information used to prepare this summary was dated: 1990.
This description is a summary from published sources, the chief of which are listed below.
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