EVOLUTION OF AN AUTONOMOUS ORE-GENERATING STRUCTURE IN THE METAGENESIS STAGE

Abstract

The principal features of the ore evolution process are traced by analysis of the conditions of generation of the Muruntau deposit. The ore genesis took place in the black shale Vendian-Lower Paleozoic association (Besapan Formation), consisting of a rhythmic alternation of siltstone, siltston-mudstone, and siliceous schist (clay content as much as 80 to 90 percent, organic matter as much as 4.6 percent) and included the following stages: a pre-ore epigenetic stage, an autometasomatic stage of impoverished ore impregnations, and a hydrothermal stage of rich ores. Mineralization of the pre-ore stage was associated with burial of the rocks at a depth of 8 to 10 km, and that of the autometasomatic and hydrothermal stages with uplifting to depths of 3 to 0.5 km. The source of the ore component (gold) was argillaceous rock formed by compaction of argillaceous sediment, a colloidal organomineral system which had sorbed gold-containing humic and fulvic acids from sea water.