川东褶皱山系“Ω形地貌”特征、成因和演化——以拟建华蓥山大峡谷地质公园为例

Characteristic,Formation and Evolution of “Ω-shaped” Landform in Fold Cordillera of Eastern Sichuan:A Case of the Huayingshan Grand Canyon Geo-park

以华蓥山中段华蓥山大峡谷地质公园内的"Ω形地貌"为例,在野外调查和资料分析的基础上,借助DEM,运用地貌学相关理论,对川东褶皱山系"Ω形地貌"特征、成因和演化进行了探讨。研究表明:该地貌在平面上呈"Ω"字形,发育于特殊的地质背景下,特点是内腔宽大,隘口窄小;华蓥山老龙洞背斜、李子沿向斜,近北东向和北西向两组节理以及走向断层——涂家院子2#逆断层是"Ω形地貌"形成的构造背景;风化作用、流水侵蚀和溶蚀作用,是"Ω形地貌"主要外营力;"Ω形地貌"的形成过程分为6个阶段:前期(构造隆起为主的阶段)、幼年期(自由沟渠阶段)、青年期(断层发育后顺坡向形成横向断层谷)、壮年初期(形成"Ω形地貌"雏形)、壮年期("Ω形地貌"最终形成)、老年期。

A kind of landform in fold cordillera of eastern Sichuan basin,because of its plane shape looks like＂Ω＂,is called ＂Ω-shaped＂landform in this paper.These landforms are different from canyons,funnel and cirque,it is necessary for us to study them.Based on long-term field reconnaissance and analysis of the data,using geomorphology theory and DEM,taking the＂Ω-shaped＂landform in Huayingshan grand canyon geo-park as an example.this paper research the feature,formation and evolution of the ＂Ω-shaped＂landform.Studies have shown that,firstly,the typical characteristic of＂Ω-shaped＂landforms is that the indocile is wader than the port; secondly,the factors,such as Haying mountain compound anticline,two groups main joints,Tu-jia-yuan-zi 2 # strike fault.etc,constitute the geologic background of ＂Ω-shaped＂landform; besides,weathering,fluvial erosion,and corrosion are main exogenic force of＂Ω-shaped＂landform.According to the geomorphology research methodology,the evolution process of ＂Ω-shaped＂landform is divided into five stages in this paper,including：antecedent（tectonic upwarping）,infancy stage（ditches developing on anticline）,neanic stage（lateral ateral fault valley developing gradually with the ateral fault yielding）,Submature（incipient ＂Ω-shaped＂landform begun to take shape）,mature stage（poort developing tended to stagnation,endocoel continued to expand,＂Ω-shaped＂landform formed finally.）and stage of old age.