Microbially Mediated Organomineralization in Paleozoic Carbonate Ooids

Abstract

This article reports the first results of studies on microbially mediated organomineralization in carbonate ooids from the Paleozoic sections of the Timan–Northern Ural region, which were formed in different environments and had different original mineral composition (calcite, Mg-calcite, and dolomite). Using a scanning electron microscope, mineralized microbial biofilms preserved in various forms and the modified morphology of primary grains under the effect of organic acids were identified. The interrelation between microbes and organomineralization has been established, which was observed in the form of conserved nuclei of the amorphous phase of calcium carbonate on the surfaces of mineralized biofilms, including EPS relics in the composition of ooid crusts. Carbon and oxygen isotope data showed the difference in Paleozoic ooid formation from saline lagoons to open shallow sea. The Raman spectra revealed the state of structure order of carbonaceous materials (CM) ranging from amorphous to weakly ordered carbon in ooids, which enables the data on the isotope composition of ooid carbonates to be considered corresponding to their primary composition and the environmental conditions under which they were formed.