{"title":"Karst Geoheritage of the Red Stone Forest in the Xiangxi UNESCO Global Geopark: Chromogenic Factors, Microgeomorphology and Dissolution Behaviour","authors":"","doi":"10.1007/s12371-024-00917-1","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>The Ordovician red karst forest is a core geoheritage site in the Xiangxi UNESCO Global Geopark and is of world-class value. However, the chromogenic factors and microgeomorphology of it have not been systematically studied, and the dissolution rate of the rocks remains unclear. The geopark contains the Sanbaidong profile, which completely traverses the bedrock of the red stone forest. We collected 355 samples from the strata within the profile for high-density geochemical analysis and found that the red stone forest contains more than one chromogenic factor. The TFe<sub>2</sub>O<sub>3</sub> content in the lower boundary of red carbonate rocks increases significantly, controlling the occurrence of red beds. The proportion of Fe<sup>3+</sup> controls the degree of red colouration. The proportions of Fe<sup>2+</sup> and Cu<sup>2+</sup> control the appearance of the greyish-green layer, and Mn<sup>2+</sup> may control the darkness of the rocks. According to the study on the coupling between elements, TFe<sub>2</sub>O<sub>3</sub> and Cu<sup>2+</sup> are mainly supplied from continental sources, and Mn<sup>2+</sup> is restricted by both marine and continental factors. The elemental distribution in layers obviously controls the concave and convex microgeomorphology. The clearest reason for this phenomenon is the CaO-SiO<sub>2</sub> proportions in adjacent layers, which are independent of the absolute values. According to an ideal model and comparisons with the Dalongdong area in Xiangxi and the Shilin UNESCO Global Geopark, it is calculated that the dissolution of the red stone forest may occur at a rate of 130.63 mg/a. The dissolution difference between the concave and convex surfaces is 1.3978 mg/a. This means that the compositional difference between the concave and convex surfaces may lead to an annual quality difference of approximately 1.07% between the layers. After tens of thousands of years, the microgeomorphology finally formed.</p>","PeriodicalId":48924,"journal":{"name":"Geoheritage","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2024-02-05","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/s12371-024-00917-1","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 Ordovician red karst forest is a core geoheritage site in the Xiangxi UNESCO Global Geopark and is of world-class value. However, the chromogenic factors and microgeomorphology of it have not been systematically studied, and the dissolution rate of the rocks remains unclear. The geopark contains the Sanbaidong profile, which completely traverses the bedrock of the red stone forest. We collected 355 samples from the strata within the profile for high-density geochemical analysis and found that the red stone forest contains more than one chromogenic factor. The TFe2O3 content in the lower boundary of red carbonate rocks increases significantly, controlling the occurrence of red beds. The proportion of Fe3+ controls the degree of red colouration. The proportions of Fe2+ and Cu2+ control the appearance of the greyish-green layer, and Mn2+ may control the darkness of the rocks. According to the study on the coupling between elements, TFe2O3 and Cu2+ are mainly supplied from continental sources, and Mn2+ is restricted by both marine and continental factors. The elemental distribution in layers obviously controls the concave and convex microgeomorphology. The clearest reason for this phenomenon is the CaO-SiO2 proportions in adjacent layers, which are independent of the absolute values. According to an ideal model and comparisons with the Dalongdong area in Xiangxi and the Shilin UNESCO Global Geopark, it is calculated that the dissolution of the red stone forest may occur at a rate of 130.63 mg/a. The dissolution difference between the concave and convex surfaces is 1.3978 mg/a. This means that the compositional difference between the concave and convex surfaces may lead to an annual quality difference of approximately 1.07% between the layers. After tens of thousands of years, the microgeomorphology finally formed.
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.
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