Tectonic framework for metallogeny of precambrian structures on the example of Kolyma and Omolon terranes (Northeast Asia)

Abstract

The example of the Omolon and Kolyma terranes (Northeast Asia) showed the influence of the regional tectonic position and geodynamic evolution of Precambrian blocks on the structure of ore deposits. The first such example is the stable consolidated structure, which was fully completed by the early Neoproterozoic. The second example is the composite terrane, similar to a fold-thrust belt. Terranes with consolidated Early Precambrian crust were a stable structure for the whole of geological history. Further ages of compression and tension did not bring about any significance changes. Ore-controlled and ore-hosted structures formed by these processes appeared as deep and steep faults of the foundation. By these pathways, subsequent tectonic and magmatic events permeated far into the terranes. That was favourable for forming large and hi-grade deposits but it restricted the range of deposit types. In contrast, the tectonic structure of the trust-faulted terranes was mobile for the whole timing scale. There Precambrian rocks were composed of allokhtones, and the trustfault structure was multiple renewed. That promoted formation of a wide range of types of mineralization, but caused dissipation of metals on numerous small-scale structures. Consequently, age and level of consolidation of the foundation is one of the most important factors of metallogeny of the Precambrian terranes. That defined the style of faulting structure (domination of steep or shallow faults), depth of the faults, morphology and geometry of the orebodies.