Model of the Gold-Bearing Placer Formation in Platform Areas (Eastern Siberian Platform)

Abstract

A model of the gold-bearing placer formation in platform areas is proposed for the first time. Placers on the platforms are formed mainly due to the Precambrian ore sources spatially confined to the basement outcrops, and, locally, Mesozoic sources formed during the tectonomagmatic activation in the paleorift and deep fault zones. Placers related to the Precambrian sources are characterized by the presence of fine and thin gold (size 0.1‒0.25 mm) and, as a rule, are not of commercial interest. They make up alluvial bar and coastal-marine allochthonous placers. They are considered as complex (mainly rare metal–titanium) placers, where gold occurs as associated component). Placers related to sources of the Mesozoic ore formation stage are assigned to the class of small and medium reserves (gold size ranging from the dust-size to 0.2‒0.25 mm or more) and are usually mined by prospectors' teams. Placers on the platforms do not make up sheet deposits, since they are formed mainly due to sources that do not generate placers. The presence of such placers indicates the proximity of ore occurrence, whose type and location can be determined based on the study of mineralogical-geochemical features of the placer gold.