Zonality and Mineral Composition of the Ore Controlling Metasomatites of the Kokkiya Gold Deposit (Kazakhstan)

Investigation of the ore-hosting metasomatites has the same importance as study of the ore substance itself. Study of metasomatites allows to define conditions of the deposit formation, its zoning, etc. The ore-and-metasomatic zoning assumes study of the patterns of formation and distribution of the products of ore-forming processes and systems in space and time during the earth’s crust development. The main factors for the vertical metasomatic zoning forming are temperature and oxygen fugacity. Importance of the oxygen increases rapidly in the shallowest formations where intensive aeration of the groundwater is possible. Here, a change of zones (facies) in the vertical direction at a short distance is observed, following not only temperature zoning, but also a sharp increase of the oxidation degree of sulfur and iron forms in the solution while approaching the surface. The regular vertical zoning of quartz-sericite metasomatites at the Kokkiya gold deposit has been defined, that represents interest for understanding of the hydrothermal solutions composition evolution, together with the paths of their infiltration, as well as for practical purposes—to develop the prospecting criteria for hidden mineralization. The given components of the vertical metasomatic zoning allow to determine the level of denudation of the ore deposits and to estimate their prospects at the depth.