ALKALINE MAGMATISM IN THE EARLY HISTORY OF THE EARTH

The processes of the Earth's atmosphere and, later, of its mantle oxid ation, which occurred at the Archean-Proterozoic boundary (2.5-2.7 Ga) as a result of planetary changes in the geodynamic environment and ra pid activation of mantle-crust interaction, brought about global metas omatic displacements of matter and the origin of zones enriched in tra ce elements in the subcrustal source areas of alkaline magmatism. The coevality between the oxidation of the atmosphere and the appearance o f alkaline rocks could not be coincidental and definitely points to fu ndamental relationships between these processes.