Physical and Microbiological Analysis of Sandstone Deterioration in the Argentine Jesuit Missions

A study of the Jesuit Missions of the Guaranis in Argentina revealed that sandstone deterioration is driven by microbial colonization, primarily cyanobacteria, alongside algae and fungi. These organisms, often deeply pigmented due to stressful conditions, thrive more abundantly on itacurú rock at San Ignacio Miní, attributed to its higher porosity facilitating water and nutrient entry. Physicochemical analysis showed ion mobilization, particularly iron (Fe), from the stone's interior to its surface, exacerbating weathering. This process transforms the sandstone into a 'protosoil,' supporting the growth of bryophytes and higher plants. The research combined physical and microbiological analyses to elucidate the mechanisms behind sandstone degradation in these UNESCO World Heritage Sites.

Barrionuevo, M. R. E., Englert, G. E., & Gaylarde, C. C. (2016). Physical and Microbiological Analysis of Sandstone Deterioration in the Argentine Jesuit Missions. Geomicrobiology Journal, 33(8), 671–676. https://doi.org/10.1080/01490451.2015.1079668