Cyanobacterial Diversity and the Role of Cyanobacteria in Formation of Minerals in the Baunt Group Hydrotherms (Baikal Rift Zone)

Abstract

A comprehensive research of water and cyanobacterial mats in Mogoysky and Shurindinsky thermal springs (Baikal rift zone) was carried out by hydrochemical, chemical, microbiological, and mineralogical methods. Detailed descriptions of the springs location and their characteristics were given. According to their chemical composition, the springs were classified as fluoride-bicarbonate (Mogoysky) and bicarbonatesulfate (Shurindinsky) types with a high concentration of fluorine. This is explained by the interaction of infiltration waters with embedding rocks. A wide diversity of cyanobacteria (14 species of 7 genera) was revealed in the investigated springs. The development of cyanobacteria in microbial mats was observed at water outflows at the temperatures of 37.8 to 76.6°C. Chlorophyll a was the predominant pigment in microbial mats of the studied springs, indicating predominance of cyanobacteria in the mat. Deposition of various pyrite forms, celestite (SrSO₄), fluorite (CaF₂), calcium carbonate, elemental sulfur, barite, and amorphous silica was found in microbial mats.