DEVELOPMENT OF DIKES AND PHENOCRYST MINERALIZATION OF LONG-EVOLVING BLOCK STRUCTURES

Abstract

The close correlation between the development of a dike complex and veinlet-disseminated gold-sulfide mineralization with the uplift of isolated local block structures is described with reference to an ore region in central Chukotka, located in the perivolcanic zone of the Okhotsk-Chukotka volcanic belt. In this zone, during tectonomagmatic activation governed by the development of the volcanic belt, there occurred a reorganization of early structures, accompanied by break-up and stepped displacement of the basement. The gold-sulfide mineralization is usually associated with block structures in the clastic level at the nodes of fault intersection. The dike facies of subvolcanic rocks farthest from the volcanic belt occur in these regions, forming extensive areas of short dikes. Ore-controlling block structures of similar makeup have been identified in the gold provinces of the fold systems of Kolyma, the Yenisey Ridge and the like; they generally tend to be associated with domelike structures. We propose to apply the name 'specially developed ore-controlling blocks' to these unusual block structures which, by the individualization of their development, focus dislocational, metamorphic and metasomatic alteration, products of igneous activity and, above all, economic mineralization, of different type and at different times.