文献类型：期刊文献

中文题名：贵州黔西接触型岩溶天坑群演化过程与成因机制初探

英文题名：Preliminary study on the evolutionary process and genetic mechanism of the contact karst tiankeng in Qianxi,Guizhou

作者：杨巍 秦媛媛 毛凯楠 邹海俊 张颖

机构：[1]贵州理工学院,贵阳550025

第一机构：贵州理工学院

年份：2026

卷号：46

期号：2

起止页码：356-365

中文期刊名：第四纪研究

外文期刊名：Quaternary Sciences

收录：;北大核心:【北大核心2023】；

基金：贵州省科技合作支撑计划项目(批准号:黔科合支撑[2021]一般463)资助。

语种：中文

中文关键词：接触型岩溶;大洞口天坑群;窗式暴露;演化机制;贵州黔西

外文关键词：contact karst;Dadongkou tiankengs;karst window exposure;evolutionary mechanism;Qianxi,Guizhou

摘要：接触型岩溶天坑发育于可溶岩与不可溶岩接触带,其演化机制与空间分异规律的研究相对薄弱。本研究以新发现的贵州黔西大洞口天坑群为研究对象,该天坑群主要发育于下三叠统嘉陵江组碎屑岩(T_(1)j^(2))与碳酸盐岩(T_(1)j^(1))接触带。利用高精度地貌调查和地质结构分析,查明了最大天坑落鲸围的深度达150m,投影面积达26.38×10^(4) m^(2)。研究识别出接触型岩溶天坑特有的“窗式暴露”现象,并建立了“接触带集中溶蚀→窗式暴露后深部溶蚀→差异塌陷”的多阶段演化模式。研究表明,构造节理、接触带水文汇集、岩性差异的三重机制耦合,以及区域构造抬升驱动下的多期古地下水位脉冲式下降是该天坑群发育的关键动力,演化过程中排泄基准面依次经历了1500~1560 m接触带、1470 m水平洞穴群至坑底落水洞深部(1340 m)的三次调整。基于形态特征和机理分析,本文提出岩溶型-接触型天坑的分类补充方案,将接触型天坑进一步细分为薄覆盖层型和厚覆盖层型两个亚类,为完善天坑分类体系、指导接触型岩溶区工程地质风险评估与地质遗迹保护提供了科学依据。
Contact karst tiankengs develop at the contact zone between soluble and insoluble rocks,yet research on their evolutionary mechanisms and spatial differentiation patterns remains relatively limited.This study focuses on the newly discovered Dadongkou tiankengs(central coordinates at 27°07′18.96″N,105°53′59.63″E)in Qianxi,Guizhou Province.These tiankengs primarily developed at the contact zone between the clastic and carbonate rocks of the Lower Triassic Jialingjiang Formation.Utilizing high-precision geomorphological survey and structural analysis,it is ascertained that the maximum depth of the largest tiankeng(Luojingwei)reaches 150 m,with a projected area of 26.38×10^(4) m^(2).This study identifies the distinctive"karst window exposure"phenomenon characteristic of this contact karst type.A multi-stage evolutionary model was established:"Concentrated dissolution at the contact zone—deep dissolution after karst window exposure—differential collapse."The research reveals that tiankeng development is primarily driven by the coupled interaction of three mechanisms:structural joint control,hydrological convergence at the contact zone,and lithological differentiation.Furthermore,regional tectonic uplift drove a multi-stage,pulse-like descent of the paleo-groundwater table.During this process,the regional discharge base level underwent three sequential shifts:from the 1500~1560 m contact zone,down to the 1470 m horizontal cave system,and finally to the sinkhole at the tiankeng floor(incised to 1340 m).Based on these findings and mechanistic analysis,this paper proposes a supplementary classification scheme for karst and contact tiankengs,further subdividing contact karst tiankengs into thin-cover and thick-cover subcategories.This classification framework provides a scientific basis for refining the tiankeng classification system,guiding engineering geological risk assessment and conservation in contact karst regions.