Surface and Subsurface Karst of the Guangwushan–Nuoshuihe Region, Northeastern Sichuan, China: Geomorphic Features Across the North–South Transition

The Guangwushan–Nuoshuihe region, on the southern flank of the Qinling Mountains in northeastern Sichuan, occupies a geographical transition between the major karst regions of northern and southern China. Its surface landforms and caves provide an opportunity to examine how features associated with these regions occur within a common geological setting. Descriptions of 110 karst-landscape sites, including 44 positive-relief features, were considered alongside the elevation distribution and morphology of 48 caves and published accounts of other Chinese karst areas. Ridge-type peak clusters, residual stone pillars, and small stone forests are prominent in the northern part of the study area, while extensive cave development is concentrated around Nuoshuihe. The caves occur at several elevations and include corridor, chamber, and branching passages, together with well-developed dripstone and flowstone deposits. The peak-cluster morphology and some branching cave systems resemble those described in southern China; the limited extent of peak forests and the prevalence of vadose caves are also familiar from northern examples. Rather than reflecting a single climatic control, this combination of landforms is best understood in relation to the region’s humid monsoon setting, carbonate lithology, structural arrangement, relief, and groundwater circulation. The comparison illustrates how northern and southern karst characteristics can overlap in mountainous transition areas.