LOCAL CRITERIA IN SEARCH FOR KARST MINERALIZATION IN THE ACHISAI ORE DISTRICT (SOUTH KAZAKHSTAN).

In the world practice, lead-zinc karst deposits occupy one of the leading positions in terms of reserves and rich ore mining. In terms of metal content, they excel all other commercial-genetic types. Karst deposits are a new commercial-genetic type for Kazakhstan. One of the promising regions for discovery of the karst deposits is the Great Karatau, known for such objects (Achisai, Karasai, Kantegi, Araltau and oth.). The area of the Achisai ore cluster is composed of thick carbonate strata of limestones and dolomites of various ages, with water-resistant horizons of marls, siltstones, and mudstones. Lead-zinc mineralization is confined exclusively to limestones and dolomites, relatively chemically pure, with a small amount of impurities of terrigenous material. The paper considers the local search attributes of lead and zinc karst mineralisation: lead and zinc sulphide mineralisation, mineralised karst, limonized rocks with mineralisation, lithological and chemical composition of rocks, metasomatic changes, geophysical and geochemical search criteria, atmo-chemical criteria, geomorphological features, tectonic breccias, and calcite veins. The above criteria can be used for large-scale forecasting and prospecting, and will allow identifying the most favourable sites to localise the mineralisation. The whole set of direct and indirect signs should be used in forecasting and prospecting works. Each of them, taken separately, cannot serve as a reliable and unambiguous search criterion of karst mineralisation. [ABSTRACT FROM AUTHOR]