摘要
黄河下游(泺口以下)发育了大量的壶穴(Pothole),按成因可以分为6种:流水侵蚀、风蚀、圆砾铸模、冰压刻、冰融水滴蚀及泄气侵蚀。流水侵蚀形成的圆形Pothole规模不一,小者直径在十余厘米,深数厘米,大者直径达数米,深1 m余;风蚀形成的圆形Pothole规模一般比较小,直径多在二、三十厘米以下,深10 cm以下,大部分穴壁缓斜,状如盘碟;圆砾铸模形成的Pothole规模一般较小,直径多在一、二十厘米以下、穴壁陡倾,状如锅穴;冰融水滴蚀形成的Pothole形态复杂,规模不一,既有穴壁缓斜的盘碟状者,也有穴壁陡倾近乎直立的近圆柱状者,直径从不足1cm到三、四十厘米,其穴缘、穴壁和穴底常有次级构造;泄气侵蚀形成的Pothole更是十分复杂,平面形态可以圆形到近圆形甚至其他复杂形态,穴壁可以非常平缓,也可以陡倾,直径从数厘米到数十厘米,深数毫米到二、三十厘米,穴缘和穴壁也常有次级伴生构造,既可单独产出,也可成群产出,同时还可以多个密集产出,状如蜂巢,这一类Pothole的成因极为独特,主要与黄河断流河床捕获的空气泄漏有关。
A lot of potholes are observed in the lower reaches of the Yellow River. According to their geneses, the potholes may be divided into six types; (1) flow-erosion; (2) wind-erosion; (3) circular boulder moulding; (4) ice-pressing; (5) ice-melt-water-erosion; (6)air-discharging erosion. The potholes formed by flow erosion are greatly varied in size: the small ones have a diameter of ten-odd centimetres and a depth of a few centimetre-s; and the large ones have a diameter of a few metres and a depth about one metre. Wind-erosion potholes are commonly small in size with their diameters no more than twenty to thirty centimetres, and their depths gener-ally below ten centimetres, and their walls gently plunged like a pot or dish. The potholes formed by casting of circular boulders are small in size, with a diameter below ten to twenty centimetres and sharply plunged walls. The Potholes formed by ice pressing are also small, with diameters ranging from ten to about thirty centimetres and depths less than ten centimetres, and have a relatively simple form. The potholes formed by ice melt water erosion have very complicated forms and variable sizes. They assume either dish-like forms with gently tilted walls or cylinder forms with almost vertical walls and their diameters ranging from several centimetres to thirty-forty centimetres. Secondary structures may often be found on their edges, walls and bottoms. There are four formation mechanisms of the ice-melt-water-erosion potholes. The potholes formed by air discharging erosion also have very complicated forms, which are considerably round to nearly round or other complicated forms. Their walls are gently or steeply plunged, with diameters from several to several tens of centimetres and depths from several millimetres to twenty-thirty centimetres, and commonly associated with secondary structures on edges and walls. They appear individually or in groups or gather like honeycombs. This type of potholes have a very unusual genesis, which is mainly related to the discharging air trapped by the riverbed during the Yellow River's zero flow period.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2002年第2期279-286,T005,T006,共10页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号499972037)
国家重点基础研究发展规划项目(编号 G1999043603)
山东省自然科学基金项目(编号 Q99E01)
