论文部分内容阅读
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。
Weathered potholes and potholes are common rock pit terrain, its formation and form completely different reasons, but easily be misunderstood and confused. The coasts of Shage Town in the west of Guangdong Province and the coast of Miaowu Island outside the Pearl River Estuary have developed weathered pits and coastal pots at the same time. In recent years, we have conducted a survey of two areas, from the geomorphology, sedimentology, petrochemistry and mineralogy and other aspects of weathering pit and coast pot hole formation process and influencing factors were demonstrated, and the two were compared . Studies have shown that weathering pits or coastal pockets can be formed on different rocks (igneous rocks and metamorphic rocks). Various evidences show that the weathering pits are formed on the weathered surface of the rocks’ surface waters. Coast potholes are formed by the erosion of sea waves : 1) Weathered pits can be formed on each highly flat rock surface above the high tide line, and weathering pits can not be formed below the average high tide line, while the coastal pothole can be formed below the average climatic surface and its formation height does not exceed the climax surface; 2) There are obvious morphological differences between the pot holes on the coast and the weathered pit, such as different side wall shape, bottom, edge of the caliber, aspect ratio, etc. 3) The roundness and sorting of the pellets in the coast pot are better than The CIA values of the sediments in the weathering pits are higher than the CIA values of the nearby ground rocks, while the ratios of the British to the Yangtze rocks in the weathered pits are higher than that of the surface rocks. However, CIA 5) the particles in the weathering pit contain a large amount of clay minerals, while the clay pots in the coast pots have no clay minerals; 6) the deposits in the weathering pits and coastal pots have a Significantly different chemistry Su migration characteristics.