Extremely deep freshwater filled cave systems are common in karst systems globally. The origin and evolution of such caves are usually attributed to hypogenic (bottom‐up) processes, in which acidic groundwater dissolves limestone from below. However, these deep cave systems can form by epigenic (top‐down) processes, with meteoric waters descending from the surface underground. The Hranice Abyss (Czech Republic), with a reached depth of 473.5 m, is the deepest mapped extent of such a system globally, although its maximum depth is unknown. Multiple geophysical data sets (gravity, electrical resistivity tomography, audiomagnetotellurics, and seismic refraction and reflection) are used to investigate the extent and formation of the Hranice Abyss. The geophysical results suggest the Hranice Abyss extends to depths of ~1 km. Further, we identify structures within the karst, including buried cockpit karst towers with several NW‐SE‐oriented valleys. The new geophysical results from the Hranice Abyss, considered in combination with geological constraints of the region (tectonic evolution and morphology of karst structure), suggest an epigenic formation process, rather than the traditionally invoked hypogenic origin. Formation by epigenic rather than hypogenic processes has implications for local and regional karst history associated with areas hosting deep karst systems.

中文翻译：

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Hranice Abyss（捷克共和国）—世界上最深的淡水洞穴例证的深层水下洞穴的后生与表观遗传起源

全球范围内，极深的淡水填充洞穴系统在岩溶系统中很常见。此类洞穴的起源和演化通常归因于次生（自下而上）过程，其中酸性地下水从下方溶解石灰石。但是，这些深层洞穴系统可以通过表观遗传（自上而下）过程形成，流水从地下表面下降。Hranice Abyss（捷克共和国）的深度为473.5 m，是全球最大的此类系统制图范围，尽管其最大深度尚不清楚。多个地球物理数据集（重力，电阻率层析成像，音频大地电磁学以及地震折射和反射）用于研究Hranice深渊的范围和形成。地球物理结果表明，Hranice深渊延伸至约1 km的深度。进一步，我们确定了岩溶内的结构，包括带有多个西北偏向谷地的地下驾驶舱岩溶塔。Hranice深渊的新地球物理结果，结合该地区的地质约束条件（构造演化和岩溶结构形态），被认为是表观成因的过程，而不是传统上称为低成因的起源。通过表观成因而非次生成因的形成对与具有深部岩溶系统的地区有关的局部和区域岩溶历史具有影响。而不是传统上称为次生的起源。通过表观成因而非次生成因的形成对与具有深部岩溶系统的地区有关的局部和区域岩溶历史具有影响。而不是传统上称为次生的起源。通过表观成因而非次生成因的形成对与深部岩溶系统区域有关的局部和区域岩溶历史具有影响。