The mineralogical-geochemical zonality of gold deposits

Mineralogical-geochemical models of the main economic types of gold deposits were elaborated by summing up vast geological, mineralogical, and geochemical data. The spatial distribution of various parameters of these models (Au and Ag concentration; productivity thickness, and morphology of ore bodies; mineral parageneses and typomorphic minerals; ore structures and textures; wallrock metasomatites; primary geochemical halos; and thermobarogeochemical characteristics) was analyzed. The analysis suggested three types of zonality: contrast gradient, noncontrast gradient, and multilevel, This article reviews each zonality type. The Karamken and Dukat deposits, with unidirectional vertical changes in all parameters traced to wedging, are an example of the contrast gradient zonality type, The: Nezhdanish; deposit is an example of noncontrast gradient zonality. Here, the main ore parameters ate stable, whereas the accompanying mineralogical and geochemical characteristics change with only slightly contrasting parameters. The Pirmirab, Mnogovershinnoe, and Sovetsk deposits are of the multilevel type, They show the multilevel distribution of ore mineralization accompanied by a wavelike pattern of parametric characteristics. Mineralogical-geochemical zonality is governed by the general factors of the ore formation (the depth and evolution of ore-bearing solutions), as well as by specific geological and structural features (the presence of structural screens, the variability of host rock composition, etc.). The elaborated models help to overcome any information deficit at the early stages of the exploration using mutually supplementary characteristics.