重庆奉节天坑地缝景区喀斯特景观特征及其形成演化分析

Characteristics and Formation and Evolution Analysis of the Karst Landscape of Fengjie Tiankeng Difeng Scenic Area, Chongqing

奉节天坑地缝景区,位于重庆市东北部,景区内喀斯特景观总体可概括为天坑、峡谷(含地缝、常态、复合式三种类型)、峰丛洼地、洞穴、象形山、水文遗迹等6大类,它们以下三叠统大冶组和嘉陵江组的碳酸盐岩地层为物质基础,或呈线状,或呈面状,或呈点状,有序分布于奉节天坑地缝喀斯特水文系统内,共同构成一个以目前全球规模最大的天坑及世界上最长的地缝为核心,峰丛、洼(谷)地、峡谷、洞穴、地下河、地表河等为重要补充,形态雄伟、典型、幽美、珍稀的奉节喀斯特景观群。同时在对景区喀斯特景观特征及区域地质背景进行分析和研究的基础上,系统研究和探讨了奉节喀斯特“横纵分异”式的形成演化过程,并认为它是一个能充分展现天坑、地缝和峡谷喀斯特复杂演化过程和规律的典型代表地,是全球天坑、地缝和峡谷喀斯特地貌演化的杰出范例。

Fengjie Tiankeng Difeng Scenic Area is located in the northeast of Chongqing.The karst landscapes in the scenic area are generally classified into six categories:tiankeng,gorge(including three types,namely Difeng,Normal gorge,Combined type gorge),peak cluster depression,cave,pictographic mountain,and hydrological heritage.All of them have been developed in the carbonate strata which are dominated by Lower Triassic Daye Formation and Jialingjiang Formation.They appear to be linear-like,planar-like or point-like and distributed in order in Fengjie Tiankeng Difeng karst hydrologic system.These geoheritages constitute a majestic,typical,beautiful and precious Fengjie karst landscape group with the largest tiankeng and the longest difeng in the world as its core,peak cluster,depression(valley),gorge,cave,underground river and surface river as important complements.Based on the analysis and investigation of the characteristics of the karst landscapes and the regional background of the landscape formation in this scenic area,the authors systematically studied and discussed the formation and evolution of horizontal-longitudinal differentiation of Fengjie karst,and hold that it is the typical representative place that could fully display the complicated evolutionary processes and regularity of tiankeng,difeng and gorge karst and is the most outstanding case of global tiankeng,difeng and gorge karst evolution.