喀斯特洞穴窝穴的形态对比与成因分析——以贵州省双河洞为例

Morphological comparison and analysis of the causes of pothole formation in karst cave:An example from Shuanghe Cave of Guizhou Province

喀斯特洞穴窝穴作为洞穴小形态的一种,记录了喀斯特地区地下河的演变过程和洞穴的发育状况。通过对双河洞系统中阴河洞、响水洞洞穴窝穴的规模、形态大小进行统计,对比了两洞穴窝穴形态的差异性并分析其成因。结果表明:在规模上,阴河洞窝穴分布面积较小,但窝穴数量相当可观,响水洞窝穴分布数量巨大,范围广泛,成千上万的窝穴沿洞穴通道两侧分布;在平面形态上,阴河洞内窝穴扁率要高于响水洞;在垂直剖面上,阴河洞内窝穴深宽比要比响水洞的偏大,且阴河洞窝穴以"V"型、倒"Ω"型窝穴为主,响水洞窝穴以倒"Ω"型窝穴为主,这与两洞穴水动力条件、地质构造、推移质、基岩、风化溶蚀作用等因素的不同密切相关。

Shuanghe Cave is located in Wenquan town, 12 km west of Suiyang county, Guizhou Province. It is a multi-layer cave system, developed in the dolomite strata in the upper Cambrian Loushanguan group. The landscape of the area comprises peak-cluster depression, peak-cluster valley and peak-cluster canyon. Faults and joints of cave area are well developed, of which joints trend in the direction of NS and NW. Con- trolled by the lithologies and geological structures, the underground river has been developed, where the pot- holes occur along the underground river of Yinhe and Xiangshui caves in Shuanghe Cave system. The annual mean temperature of the area is 15.5 ℃ and annual precipitation is about 1,210 mm. In order to compare the difference in pothole morphology and formation cause in the two caves, the pothole geometric features inclu- ding the length of hole axes, hole depth and trend direction of the potholes long axis were measured in the field, by using measuring tape and laser range device. Statistical results show that distribution area of the potholes in Yinhe cave is small, with a considerable number of the pothole. However, potholes in Xiangshui cave are widely distributed, with thousands of the holes occur along both sides of the cave channel. Geomet- rically, the pothole oblateness of Yinhe cave is generally higher than that of Xiangshui cave, while the hole depth/width ratio of theYinhe cave is higher than that of Xiangshui cave. Morphologically, the potholes are dominated by both ＂V＂ and inverted ＂Ω＂ types in the Yinhe cave, while in the Xiangshui cave the potholes of inverted ＂Ω＂ type are predominant. This is closely related to the two cave water dynamic condition, geolog- ical structure, bed load, bedrock, weathering.