作　　者： ; ; ; ; ; ; ; ; ;

机构地区： 华南师范大学地理科学学院

出　　处： 《第四纪研究》 2013年第5期1016-1033,共18页

摘　　要： 风化坑和壶穴都是常见的岩石坑穴地形,其形成原因和形态完全不同,但容易被误解和混淆。广东西部沙扒镇海岸和珠江口外庙湾岛海岸同时发育了风化坑和海岸壶穴。近年来我们对两处地区进行了考察,从地貌学、沉积学、岩石化学和矿物学等各个方面对风化坑和海岸壶穴的形成过程和影响因素进行了论证,并将两者进行了对比。研究表明在不同的岩石(火成岩和变质岩)上均能形成风化坑或海岸壶穴,各种证据显示风化坑形成于岩石表面积水的风化作用,海岸壶穴则是由海浪的侵蚀作用而形成:1)风化坑可以形成于高潮线以上的各个高度平坦的岩石面上,平均高潮线以下不能形成风化坑,而海岸壶穴可形成于平均高潮面之下,其形成高度不超出高潮面;2)海岸壶穴与风化坑在形态上有明显区别,如不同的侧壁形态、底部、口径边缘及宽深比等;3)海岸壶穴中堆积物颗粒磨圆度和分选度好于风化坑中颗粒;4)风化坑内堆积物的化学蚀变指数CIA值均高于附近地面岩石的CIA值,而风化坑内堆积物中矿物的英长比高于地表岩石的英长比,但CIA值和英长比均不能区分海岸壶穴和风化坑中的堆积物;5)风化坑内颗粒含大量的粘土矿物,而海岸壶穴中无粘土矿物;6)风化坑和海岸壶穴的堆积物具有显著不同的化学元素迁移特征。 Weathering pits and marine potholes are depressions on exposed rock surfaces with different morphological features due to completely different origins and formation processes.However,they are often confused with each other and considered to be the same thing formed by glaciations in China.In recent years,we have investigated two places with different geographic environments,one of which is Shapa Town in west Guangdong on the coast of South China,and the other is Miaowan Island off Pearl River Estuary. Weathering pits and marine potholes are found in these two places,even though the coast of Shapa Town is composed of granodiorite and granite gneiss while that of Miaowan island is of biotite granite.This paper presents a detailed comparison between the weathering pits and the marine potholes developed on the coasts of Shapa and Miaowan to explain the differences in their origins and formation processes.The studies in respects of geomorphology,sedimentology,petrochemistry and mineralogy show that the formation of the weathering pits results from localized weathering induced by the stagnant water in rock surface depressions,while the marine potholes are produced by mechanical erosion of sea waves,although both are capable of being formed in the same rock.The evidences to set them clearly apart include the following：1）the weathering pits in these two places are formed at various heights above mean high tide level,but only on the flat rock surfaces facing upwards.There is no weathering pit that can be formed under the mean high tide level in these two places,while the positions of the marine potholes can extend to levels lower than the high tide level,but not more than 3m above the level; 2）the marine potholes are morphologically distinct from the weathering pits in their side walls,rims,bottoms,breadth-to-depth ratio,etc.because of their different formation processes; 3）roundnesses and sorting degrees of the clastic particles in the marine potholes are better than those in the weathering pits because the potho

关 键 词： 风化坑 海岸壶穴 成因 广东

领　　域： [天文地球] [天文地球] [天文地球] [天文地球] [天文地球]