Calcium Carbonate Growth with the Ring Structure of Stalactite-Type Minerals in a Tuff Breccia

Microbially induced carbonate precipitation (MICP) has attracted worldwide attention as an environmentally friendly ground restoration technology in response to geohazards. This study describes the relationship between calcium carbonate growth within stalactite-type minerals formed around fractures in tuff breccia and microorganisms. Scanning electron microscopy revealed that calcium carbonate was precipitated in the interstices of rings formed in stalactite-type minerals, as if the carbonate minerals enhanced the strength of the silicate minerals. In addition, X-ray powder diffraction analysis detected that the calcium carbonates were calcite and vaterite. Moreover, microorganisms, such as diatoms and green algae, inhabited the interstices and, consequently, MICP by these microorganisms could play a role in the stability of outcrops. The stable isotope ratios of delta C-13 and delta N-15 and the mass spectral signals of the demineralized samples also encouraged diatoms and green algae to be involved in the formation of minerals.

Automated summary

This study explores the relationship between microbially induced carbonate precipitation (MICP) and the growth of calcium carbonate within stalactite-type minerals. A stronger stability in outcrops is observed as the carbonate minerals enhance the strength of silicate minerals, possibly due to the involvement of microorganisms like diatoms and green algae in mineral formation. The stable isotope ratios and mass spectral signals also support the idea of microbial involvement in the process of mineral formation.