双河洞层状溶洞与区域河流阶地发育耦合关系探析

Analysis of Coupling Relationship Between Multi-layer Caves in Shuanghe Cave National Geopark and Regional Fluvial Terraces

双河洞岩溶洞穴系统是双河洞国家地质公园的核心景观,溶洞主体发育于寒武系中上统白云岩地层中,层状延伸的4层溶洞反映了洞穴系统的阶段性发育过程。野外调查显示,与双河洞层状溶洞一致,池武溪河谷和芙蓉江上游旺草盆地保存了4级河流阶地,其形成对多层溶洞的发育具有指示意义。本文从双河洞岩溶洞穴系统的成层性出发,分析了区域河流阶地的发育特征,探讨了层状溶洞与区域河流阶地发育的耦合关系。结果表明,在池武溪河谷,多层溶洞和河流阶地具有发育对应关系,而旺草盆地阶地级差明显低于池武溪河谷,反映了同一流域不同构造部位的地貌发育差异。根据阶地和溶洞发育耦合关系分析,开展高精度阶地定年将有助于厘定双河洞多层溶洞系统的阶段性发育时代。

Shuanghe cave is the core landscape of Shuanghe Cave National Geo-park,which is developed in the dolomite strata of Middle-upper Cambrian.Horizontal four-storey caves extending from west to east reflect the episodic evolution of the karst cave system.Though field investigation it is found that there are four fluvial terraces both in Chiwuxi valley and Wangcao basin of upper Furong River,which commendably correspond to the four-storey caves in Shuanghe cave.These multi-layer caves and terraces directly indicate regional staggered tectonic uplift.In this paper,we analyzed the stratification of Shuanghe cave system and the distribution of the fluvial terraces.And then we discussed the coupling relationship of the landform development between multi-layer karst caves and fluvial terraces.The results show that in Chiwuxi valley,there is a good development correspondence between the four-storey caves and the fluvial terraces.But in Wangcao basin,the terraces gradients are significantly lower than the terraces in Chiwuxi Valley,which reflect a different geomorphological development process in same basin.According to the coupling relationship between the fluvial terraces and the multi-layer karst caves,we hold that high-precision terraces dating will be an effective way to determine the forming time of multi-layer caves in Shuanghe cave.