| 丹霞山陡坡上风化洞穴的基本特征及成因探讨 |
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| 引用本文： | 史月欣,陈留勤,杜丁丁,柴乐,王子涵.丹霞山陡坡上风化洞穴的基本特征及成因探讨[J].热带地理,2023,43(1):103-114. |
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| 作者姓名： | 史月欣 陈留勤 杜丁丁 柴乐 王子涵 |
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| 作者单位： | 东华理工大学 地球科学学院，南昌 330013 |
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| 基金项目： | 国家自然科学基金项目(41962009);江西省社科基金“十四五”（2021年）地区项目(21DQ45) |
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| 摘 要： | 风化洞穴在全球不同气候区广泛发育，其形成过程和主控因素是地貌学研究的热点问题，但形成机制至今仍存在不少争议，尤其对丹霞地貌区风化洞穴的研究还较少。丹霞山是世界自然遗产地“中国丹霞”的典型代表，陡坡上发育形态和规模各异的风化洞穴，是丹霞地貌的重要景观要素，为认识亚热带湿润气候风化洞穴成因提供了良好的机会。文章以丹霞山砾岩和砂岩陡坡上的5处典型风化洞穴为研究对象，利用野外考察、形态测量、气象监测、样品显微观察及盐化学实验等方法，在已有研究的基础上进一步对湿润气候丹霞地貌区风化洞穴的特征和成因进行探讨。结果表明：1）在砾岩中发育的洞穴一般个体形态较大，洞穴具有较明显的向上和向内生长趋势；砂岩中发育的洞穴大多密集排列，形态较小，常具有蜂巢结构。2）岩石性质是洞穴发育的基本影响因素，在宏观尺度上决定了洞穴的发育位置和排列方式，也决定了不同岩性下发育的风化洞穴的形态特征。在微观尺度上，岩石含有较多长石、钙质胶结物等易溶矿物组分，在酸性雨水渗流过程中发生化学溶解，加上盐结晶作用导致岩石微观结构破坏，诱发洞穴初始形成。3）洞穴尺寸变大后，洞穴内适宜的微气候是洞穴演化的关键因素，为水和盐的聚集及盐风化提...
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| 关 键 词： | 风化洞穴 丹霞地貌 微气候 自组织 丹霞山 |
| 收稿时间： | 2022-09-10 |
Basic Characteristics and Genesis of Cavernous Weathering Features on the Steep Slopes of Danxia Landscape in Danxiashan UNESCO Global Geopark |
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| Yuexin Shi,Liuqin Chen,Dingding Du,Le Chai,Zihan Wang.Basic Characteristics and Genesis of Cavernous Weathering Features on the Steep Slopes of Danxia Landscape in Danxiashan UNESCO Global Geopark[J].Tropical Geography,2023,43(1):103-114. |
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| Authors: | Yuexin Shi Liuqin Chen Dingding Du Le Chai Zihan Wang |
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| Institution: | School of Earth Sciences, East China University of Technology, Nanchang 330013, China |
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| Abstract: | Cavernous weathering is widely distributed in different climate zones worldwide. The dominant controlling factors and their formation processes have long been discussed in the geomorphological community; however, many controversies remain. In the danxia landscape, various forms of cavernous weathering develop on steep slopes. They are important elements of the landscape and provide shelter for the preservation of many precious historical cultures, yet there have been few studies investigating their origin. Danxiashan is representative of the Natural World Heritage site 'China Danxia', with widespread cavernous weathering features of various sizes and shapes, providing a good opportunity for investigating the origin of cavernous weathering in subtropical humid climates. Typical caverns on sandstone and conglomerate slopes at five sites in Danxiashan were selected and studied by field investigation, morphological measurement, meteorological monitoring, sample microscopic observation, and salt experiments. The results show the following. First, the diameters of the cavern openings vary from centimeters to meters, and the shape of the cavern openings is elliptical to elliptical. The tafoni on conglomerate slopes are generally large and tend to grow upward and inward, while the caverns on sandstone slopes are generally small and arranged in a honeycomb-like structure. Second, lithology is fundamental for the development of caverns. At the macroscopic scale, it determines their location and arrangement because the caverns generally align within the lamination of beddings or cross-beddings. Indeed, the morphological characteristics of caverns developed differently under varying lithologies. At the microscopic scale, the red beds consist of abundant soluble mineral components, such as feldspars and carbonate cements, which are chemically dissolved in the seepage of acid rainwater, the salt crystallization of which leads to the destruction of the rock texture. Collectively, they would have initiated the formation of caverns. Third, the favorable microclimate within the caverns is a key factor that is water and salt accumulation, and consequently, salt weathering and enlargement of the caverns over time. Notably, the microclimate within the Jinshiyan Cave has provided favorable conditions for algae colonization, which controlled the formation of the cell-and-wall structure of the regular honeycombs at the Longlingpian Rock. Finally, the dominant controlling factors were dissimilar between caverns and interplayed in different development stages of cavernous weathering, the entire progression of which was potentially regulated by a self-organized mechanism. However, the influencing factors and critical values of the positive and negative feedback mechanisms require further study. |
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| Keywords: | cavernous weathering danxia landscape microclimate self-organization Danxiashan |
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