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Lichenic alteration and mineralization in calcareous monuments of northeastern Spain

1995; Taylor & Francis; Volume: 13; Issue: 4 Linguagem: Inglês

10.1080/01490459509378023

1521-0529

Francesca Blázquez, F. Calvet, M. Vendrell,

Karst Systems and Hydrogeology

Biodeterioration processes on three Spanish calcareous monuments (Scipio's Tower, Olèrdola Wall, and the Naveta d'Es Tudons) were investigated. Scipio's Tower and Olèrdola Wall, both located in Catalonia, were built with blocks of bioclastic pack‐stones (foraminifera, bivalves, gastropods, red algae, echinoderms) of the Langhian (Middle Miocene) Age. The Naveta d'Es Tudons, located on the island of Menorca, was constructed with blocks made up of bioclastic packstones, partially dolomitized and dedolomitized, and is of Miocene Age. The main organisms that inhabited these three monuments were lichens [mainly Dirina massiliensis Durieu et Mont, Verrucaria nigrescens Pers., Caloplaca aurantia (Pers.) Hellb., Caloplaca velana (Massal.) Du Rietz, Caloplaca erythrocarpa (Pers.) Zw., Petractis thelotremalla (Bagl.) Vezda, and Strigula calcarea Bricaud et Roux], which caused the main alteration of the rock. The distributions of these lichens were determined and their actions on the stone were studied by different techniques. From the samples studied, a general and complete alteration profile was proposed and described. In this profde from the external area of the stone to the unaltered substratum, five zones were distinguished: lichen thallus, microcorrosion surface, altered zone, transition zone, and finally the unaltered zone or substratum. A model of evolution of these zones was also developed. Some structures found in the different zones of these profiles were morphologically described and filaments and spheres were identified. In the same way, some diagenetic products found in these zones were described and related to the processes that originated them. An interpretation of these structures and products and their relation to organisms and microorganisms was attempted.