GENESIS OF GOLD NUGGETS AND THE TRENDS OF THEIR GLOBAL DISTRIBUTION

Abstract

I have had a rare opportunity to study the numerous gold nuggets in special collections of the USSR, in museums in Moscow, Leningrad (St. Petersburg), and Sverdlovsk (Yekaterinburg), to see them in mine workings and to examine the exhibits of gold nuggets in some European museums. The data I have obtained plus published data have enabled me to approach the problem of the genesis of these remarkable formations from a new standpoint; specifically, to try to study the spatial position of the areas of their occurrence in zones of the Earth's crust with different histories of geodynamic development. The results of these studies permit me to assert that the 'nugget' regions occupy a systematic position in the global structure of the Earth, and moreover that they differ for nuggets of different morphological types. The concentration of gold nuggets in placers appears to be a consequence of intensive erosion of the upper parts of the ore columns of hydrothermal deposits when gold-bearing lithosphere blocks are uplifted; as N.A. Shilo quite properly emphasizes, the placer-forming processes are closely associated with those movements. The data presented above show that gold nuggets are indicators of a special geodynamic regime of development of ore-bearing regions. In addition, gold nuggets should be considered a material reflection of locally manifested features of gold migration and concentration.