Lichens as possible agents of sandstone deterioration in Jesuitic ruins of San Ignacio Miní (Misiones Province, Argentina)

Abstract

The ruins of San Ignacio Miní, in NE Argentina, Misiones Province, included by the UNESCO in the list of World Heritage in 1984, were built in the 18th century by the Guarani people under the supervision of the Jesuite Congregation. The ruins are located in a tropical weather zone, exposed to extreme conditions of heat and humidity affecting the rocks used in its construction. These rocks are identified as siliceous sandstones, mainly formed by rounded to subrounded clasts, with scarce angulose particles, containing 96% quartz. Weather characteristics encourage the growth of vascular plants as well as algae and mosses and other organisms that damage materials. Among these, there are 18 lichen species (belonging to 18 genera), 8 foliose, 3 fruticose and 7 crustose. The damaging action of these lichens has been observed through SEM observations and EDAX microanalysis of rock samples colonized by Caloplaca sp. and Buellia sp.

Keywords

• sandstone
• lichens
• sem edax studies
• characteristic tests
• misiones province
• argentina