广东庙湾岛风化坑的地貌特征及成因  

Topography,Morphological Characteristics and Formation of Weathering Pit in the Miaowan Island, Guangdong, China

作　　者：黄日辉[1] 刘韫[1] 王为[1] 

机构地区：[1]华南师范大学地理科学学院,广州510631

出　　处：《热带地理》2016年第2期284-295,共12页Tropical Geography

基　　金：国家自然科学基金项目(41571002)

摘　　要：风化坑是常见的岩石坑穴地形,但容易被误解或与其他成因坑穴地形混淆。通过对庙湾岛风化坑地貌特征及形态参数进行详细测量和分析,采集风化坑内残积碎屑物、坑外岩石和当地风化壳样品进行粉晶X射线荧光光谱化学主量分析(XRF)和X射线衍射矿物分析(XRD),对风化坑发育的成因机制进行了探讨,并得出以下结论:1)风化坑的发育与地形坡度有关,通常出现在平坦裸露的岩石面上。2)风化坑的形态特征表现为宽且浅,口缘有出水口,底部平坦,侧壁最凹处与出水口高度一致,其口径发育的速度远大于深度,长轴发育速度远大于短轴。3)同一岩石面上的风化坑具有不同的大小和深度,显示了其发育程度不一,其最大、最小深度对比反映了风化坑的发育过程。4)风化坑碎屑物与表岩之间的元素迁移和化学蚀变指数(CIA值)的差异,反映了风化坑的化学风化成因。5)风化坑碎屑物的英长比大于表岩,证明了化学风化导致的矿物差异风化作用。研究表明:庙湾岛风化坑形成和发育的主要作用为坑内积水的化学风化。Weathering pit is a common rock landscape in the East of China and there are a variety of explanations for its formation. In the thesis, the topography features and its morphological parameters of the weathering in the Miaowan Island are measured and recorded in detail. Also, the debris inside the weathering pits, parent rocks and weathering profile samples were collected. After that, they were analyzed by XRF（X Ray Fluorescence） and XRD（X-Ray Diffraction）. Based on the previous factors, the topography and morphological features, chemistry and its mineral features of weathering pit were put under analysis and the genetic mechanism of the development of weathering pit is explored as well. According to the results, firstly, the development of weathering pit is not relevant to its altitude. Weathering pit of various sizes and depths might appear on any rocks that are flat and exposed at any height. Secondly, the various sizes and depths of weathering pit represent different degrees of development. Thirdly, the speed of the development of the caliber in weathering pit is higher than that of its depth. Also, the speed of the development of weathering pit＇s long axis is higher than that of its short axis. There are spillways in majority of weathering pits and the groove on the wall is of the same height of the spillway. Fourthly, the element migration characteristic of the debris in the weathering pits and difference of CIA value（chemical index of alteration） between the debris and the parent rocks represent the chemical weathering cause of the weathering pit. Fifthly, the difference of the ratio of quartz to feldspar between the weathering pit＇s debris and parent rocks can represent the cause for weathering pit by different weathering of minerals.

关 键 词：风化坑 形态特征 化学元素 矿物 庙湾岛 

分 类 号：P512.1[天文地球—地质学]