广西环江锥状峰丛喀斯特景观演化机制

Evolution Mechanism of Dolomite Karst Peak Cluster-Canyon Landform:A Genesis View on Huanjiang,Guangxi

广西环江喀斯特世界自然遗产提名地是贵州荔波喀斯特世界自然遗产地的拓展地。环江喀斯特地貌发育演化受岩性、地质构造、断层、节理、裂隙和地下水文系统等因素影响。岩层由纯度较高的石灰岩和白云岩等可溶性碳酸盐岩构成,地壳运动使该地抬升,岩层受力发生褶皱并隆起断裂,断层节理发育;降雨、较高的温度以及地表-地下水对可溶性岩石进行侵蚀-溶蚀作用,使侵蚀基准面下降,河流下切,地表因长时间受剥蚀和溶蚀,地貌演化由幼年期经青年期进入壮年晚期。发育成峰丛谷地、洼地、峡谷及峰林洼地、谷地、盆地和多层洞穴等为主的形态多样的锥状喀斯特地貌景观。环江喀斯特自寒武纪以来经历了形成山间盆地和石炭系巨厚碳酸盐岩的沉积成岩阶段及喀斯特化作用,地貌发育演化经过3个主要阶段,即褶皱断块山地―盆地形成阶段、喀斯特峰丛―峰林发育阶段和喀斯特峡谷形成阶段。演化模式遵循峰丛洼地→峰丛谷地→峰丛峡谷→峰林洼地→峰林谷地地有序正向演替规律。揭示了热带-亚热带锥状喀斯特地貌发育主要阶段及演化过程。

Guangxi Huanjiang Karst has been nominated as a site of World Natural Heritage. It is an expanding part of Guizhou Libo Karst World Natural Heritage. Huanjiang karst landform evolution is affected by lithology, geological structure, faults, joints, cracks and subsurface hydrological system and other factors. The rocks in Huanjiang are composed of high purity limestone, dolomite and other soluble carbonate rocks. Crustal movement made the area uplift. The rock stress caused fold fracture and uplift, faults joint development. Rainfall, higher temperature and soluble rocks erosion-corrosion effect caused by surface - groundwater made the erosion base level fall and the rivers incised conduct. The surface has undergone the denudation and erosion for a long time, and the process has made the landform evolve from infancy through adolescence into manhood late. They developed into fengcong valley, depression, canyon and fenglin depressions, valley, basin and multilayer cave as the main morphological diversity of cone Karst landscape. The formation of Huanjiang Karst has experienced the effects of intermontane basin, the diagenesis of the thick carbonate rock of the Carboniferous and the Karst action since the Cambrian, and the geomorphological evolution has gone through 3 main stages, namely, fold block mountain basin formation stage, Karst peak cluster-peak forest developmental stages and Karst Canyon formation stage. Evolution model follows the succession law orderly, which is from fengcong depression to peak valley, fengcong gorge, fenglin depression and fenglin valley. It reveals the main stages and evolution process of tropical-subtropical cone karst development.