[Transformation of carbonate minerals in a cyano-bacterial mat in the course of laboratory modeling].

A laboratory model of a cyano-bacterial mat with mineral layers of carbonates was used to examine the dynamics of the transformation of calcium-magnesium carbonate under the conditions of a soda lake. The activity of various organisms of the cyanobacterial community results in conditions under which the Ca-Mg carbonate precipitate undergoes changes. The crystal lattice of the initial carbonate is restructured; its mineralogical composition changes depending on the conditions of the mat. In magnesium calcites, which are formed under such low-temperature conditions, a rudimentary cation adjustment can occur with the formation of dolomite domains. These experiments confirm the hypothesis that the dolomite found in stromatolites is of a secondary origin and can be formed in the course of transformation of Ca-Mg carbonates under alkaline conditions in an alkaliphilic cyanobacterial community.