Physicochemical Conditions of the Existence of Early Cambrian Chemotrophic Microbiota in the Zone of Influence of Sulfide Ore-Forming Hydrothermal Solutions

Abstract

Complex studies of the Early Cambrian Kyzyl-Tashtyg pyrite deposit (East Tuva) allowed us to reconstruct the paleohydrothermal systems, to understand the physicochemical conditions of hydrothermal processes, and to study the patterns of existence of ancient hydrothermal biota in the zone of activity of solutions participating at all stages of the formation of ore-bearing structures starting from the influence of postmagmatic fluids and up to low-temperature hydrotherms. The data on the biota reported were obtained during study of the objects occurring in the zone of influence of relatively low-temperature hydrothermal systems. In some cases, microorganisms were found in basaltic complexes hosting ore bodies; in other cases, fauna was related to the ferrous–siliceous deposits. It was found that microorganisms in basaltic amygdules were formed at temperatures of ~110–140°C under the influence of hydrothermal solutions of the Kyzyl-Tashtyg deposit. Much lower temperatures (up to 100°C) existed during the evolution of microfossils in the quartz–hematite hydrothermal structures of the Kyzyl-Tashtyg deposit.