Formation and evolution of the karst pastoral landscape in Puzhehei

REN Shichuan; YANG Xiaoyan; CHAI Zhengjiao; TIAN Wenrui; YANG Fan

doi:10.11932/karst20240608

Abstract：Traditional karstology examines karst geomorphic landscapes as geological processes occurring at the interface of lithosphere and hydrosphere.It concludes with a discussion on how factors such as structure,stratigraphy,hydrology,climatic conditions and neotectonic movements influence karst development.The emergence of theories in Earth system science has opened up new avenues for the advancement of karstology. Based on a substantial collection of geological relics,this study examines the formation process of the karst ecological pastoral landscape in Puzhehei from the perspective of Earth system science.It is posited that this evolution occurred gradually over hundreds of millions of years.From the Devonian period to the end of the Triassic period,a set of strata dominated by carbonate rocks with shallow marine and platform facies were deposited,which established a favorable lithospheric foundation for the karst development in the study area.The Indosinian movement and Yanshan movement from the Jurassic to the Cretaceous laid an important structural and topographic foundation for the study area.The period from the Paleogene to the present marks the formation of the karst ecological pastoral landscape in Puzhehei,which can be further divided into four stages.In the first act of the Himalayan movement,the northwest fault of the study area was reactivated,forming a topography characterized by high elevations in the south and low elevations in the north,as well as high terrain on the eastern and western sides and a low area in the center.This represents the initial stage of karst development.In the second act of the Himalayan movement,the northern plate of the Yangqi fault rose,creating a low-lying center around Luoshuidong lake.This led to the formation of fault depression lake basin in Puzhehei,marking an important stage in karst development.In the third act of the Himalayan movement,the uplift of the northern panel of the Yangqi fault intensified,leading to the gradual disappearance of surface water outlets.Consequently,the lake surface rapidly expanded southward,reaching the vicinity of Qiubei county.During this process,triangular fault basins were fully formed,and karst was further developed.Since the Late Pleistocene,the uplift of the crust and the headward erosion of the Beimen river have created a new water outlet in the surrounding area.Consequently,the lake water rapidly drained,resulting in the formation of a karst landscape.Since the Holocene,under the influence and transformation of human activities,today's pastoral landscape has come into being. According to the evolutionary process,this study preliminarily predicts the changing trends of landscape and lake water quality,and proposes several protective suggestions.First,conducting a survey on resource carrying capacity and standardizing tourism management.Second,strengthening infrastructure development and improving the sewage system.Third,establishing a scientific monitoring system for regular tracking and monitoring.Fourth,enhancing public awareness of environmental protection through effective science communication.