乌江下游岩溶地貌形态特征初探--以重庆武隆及其邻近地区为例

Preliminary study on morphology features of karst in the lower reaches of Wujiang River——A case in Wulong,Chongqing and the surrounding area

乌江下游为典型的亚热带岩溶中山峡谷地貌,主要以大型的岩溶峡谷、天生桥和大的天坑以及大型溶洞、地下河及丰富多彩的次生沉积物为特征。本文主要分析了乌江下游的岩溶个体形态特征及层状地貌面的岩溶形态组合特征,探讨了乌江下游岩溶地貌的演化过程,认为:(1)乌江下游地区的层状地貌分为两级夷平面、一级溶蚀面、五级水平溶洞和三级阶地;(2)不同地区岩溶形态特征有明显差异:在鄂西期地面上,地面完整性较好,以低矮的峰丛和平坝、大的浅洼地相组合。山原期地面,不同地区岩溶形态组合特征有所差别:在水系裂点以下地区,主要以峰丛-峡谷组合为主;河流裂点以上的上游地区,地面保存相对完整,为锥状峰丛、深洼地景观。盆地期溶蚀面以峰丛-槽谷、谷地为主。(3)乌江下游岩溶地貌的形成,经历了鄂西期、山原期、盆地期和峡谷期地貌演化阶段,并形成鄂西期、山原期岩溶夷平面、盆地期溶蚀面和深切峡谷。

The geomorphology is typical subtropical karst middle mountain and gorge with characteristics of large scale karst gorge,natural briddge,tiankang,cave and underground river as well as colorful second deposits at the lower reaches of the Wujiang River.The karst individual feature and feature complex on stratified relief plane are analyzed and the evolution of the karst morphology at the lower reaches of the Wujiang River is studied in the paper.It is believed that 1） the stratified relief plane can be divided into 2 grade planation surfaces,1 grade corrosion surface,5 grade horizon karst caves and 3 grade terraces;2） there are obvious different karst feature among different period of planation surfaces,such as the surface is integrated with lower peak-cluster and karst basin and depression on the Exi Surface,but the karst feature changes in different areas on the Shanyuan Surface,which is dominated by peak-cluster and gorge above the knick point and cone karst peak-cluster and deep depression landscape with relatively integrated surface below the knick point;yet on the Pendi Surface,the morphology is dominated by peak-cluster and uvala as well as valley;3） the karst morphology once experienced 3 periods of evolution as the Exi period,Shanyuan period and Pendi period as well Xiagu period,which leading to the formation of the Exi and Shanyuan karst planation surfaces and the Pendi corrosion surface as well as the Xiagu gorge.