{"title":"Calcite Precipitation on Excavated Andesite Surfaces from the Archaeological Sites of Aigai and Assos (Turkey)","authors":"Çağlayan Deniz Kaplan, Hasan Böke","doi":"10.1007/s12371-024-00952-y","DOIUrl":null,"url":null,"abstract":"<p>The conservation interventions of crusts or patinas formed on the surfaces of stone monuments should be evaluated within a comprehensive approach in archaeological excavations, taking into account their material characteristics. In this study, the mineralogical, chemical and microstructural characteristics of whitish crusts formed on the surfaces of buried and later excavated andesite surfaces at the archaeological sites of Aigai and Assos (Turkey) were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDS) analyses in order to establish a conservation approach at the archaeological sites. The whitish crusts formed on the excavated andesite surfaces are mainly composed of calcite with freshwater diatom species. Calcite is most likely formed by the alteration of plagioclase by carbon dioxide in the soil during the burial of the andesites. In the soil, CO<sub>2</sub> reacts with plagioclase to produce kaolinite and calcite which are precipitated on the andesite surfaces after excavation. The presence of freshwater diatom species in the whitish crusts may indicate that the andesite remains were buried in the waterlogged soil for many years and later excavated. Therefore, whitish crusts should not be cleaned from the andesite surfaces, as they are a sign of the burial history of the monuments and a protective layer against weathering.</p>","PeriodicalId":48924,"journal":{"name":"Geoheritage","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geoheritage","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s12371-024-00952-y","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The conservation interventions of crusts or patinas formed on the surfaces of stone monuments should be evaluated within a comprehensive approach in archaeological excavations, taking into account their material characteristics. In this study, the mineralogical, chemical and microstructural characteristics of whitish crusts formed on the surfaces of buried and later excavated andesite surfaces at the archaeological sites of Aigai and Assos (Turkey) were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDS) analyses in order to establish a conservation approach at the archaeological sites. The whitish crusts formed on the excavated andesite surfaces are mainly composed of calcite with freshwater diatom species. Calcite is most likely formed by the alteration of plagioclase by carbon dioxide in the soil during the burial of the andesites. In the soil, CO2 reacts with plagioclase to produce kaolinite and calcite which are precipitated on the andesite surfaces after excavation. The presence of freshwater diatom species in the whitish crusts may indicate that the andesite remains were buried in the waterlogged soil for many years and later excavated. Therefore, whitish crusts should not be cleaned from the andesite surfaces, as they are a sign of the burial history of the monuments and a protective layer against weathering.
期刊介绍:
The Geoheritage journal is an international journal dedicated to discussing all aspects of our global geoheritage, both in situ and portable. The journal will invite all contributions on the conservation of sites and materials - use, protection and practical heritage management - as well as its interpretation through education, training and tourism.
The journal wishes to cover all aspects of geoheritage and its protection. Key topics are:
- Identification, characterisation, quantification and management of geoheritage;
- Geodiversity and geosites;
- On-site science, geological and geomorphological research:
- Global scientific heritage - key scientific geosites, GSSPs, stratotype conservation
and management;
- Scientific research and education, and the promotion of the geosciences thereby;
- Conventions, statute and legal instruments, national and international;
- Integration of biodiversity and geodiversity in nature conservation and land-use
policies;
- Geological heritage and Environmental Impact Assessment studies;
- Geological heritage, sustainable development, community action, practical initiatives and tourism;
- Geoparks: creation, management and outputs;
- Conservation in the natural world, Man-made and natural impacts, climate change;
- Geotourism definitions, methodologies, and case studies;
- International mechanisms for conservation and popularisation - World Heritage Sites,
National Parks etc.;
- Materials, data and people important in the history of science, museums, collections
and all portable geoheritage;
- Education and training of geoheritage specialists;
- Pedagogical use of geological heritage - publications, teaching media, trails, centres,
on-site museums;
- Linking the United Nations Decade of Education for Sustainable Development (2005- 2014) with geoconservation.