Active karst systems can offer good analogues for paleokarst reservoir modelling as they can provide links between present karst system geometries and the final reservoir architecture. Although clastic sediments are a characteristic and commonly conspicuous component of modern karst systems, their impact on the surveyed cave morphology has received limited attention. Here we address this topic by investigating the spatial and volumetric distribution of clastic sediments in a large karst cave hosting an active fluvial channel in northern Greece and discretize these in a geocellular framework. Mapping of cave floor sediment-types was supplemented by local stratigraphic logging of relict sediment terraces and electrical resistivity tomography in parts of the cave. Four resistivity groups were identified and interpreted as low- and high-porosity siliciclastic sediments, interbedded marble clasts, and host rock (marble). Sediment infill thickness ranges from 25 m to >45 m at the time of measurement; corresponding to a minimum of 64–95% of the cross-sectional area of the karst cavity in the surveyed part. These observations demonstrate that under certain circumstances, allochthonous siliciclastic sediments can form a significant volumetric component in karst systems and, by extension, in paleokarst reservoirs originating from similar karstic systems. This highlights the importance of understanding the context, organization and development of the initial karst system when characterizing paleokarst reservoirs. Mapping of sediment thickness is not usually carried out during cave surveys, which primarily focus on recording open cavities accessible to man. This implies that survey data concerning the shape and volume of cave systems and statistics compiled and derived from them should be handled with care when applied to paleokarst reservoir modelling.

主动岩溶系统可以为古喀斯特储层建模提供良好的类似物，因为它们可以提供当前岩溶系统几何形状与最终储层构造之间的联系。尽管碎屑沉积物是现代喀斯特系统的一个典型特征，并且通常很明显，但它们对所调查的洞穴形态的影响受到的关注却很少。在这里，我们通过研究希腊北部一个拥有活跃河流通道的大型喀斯特洞穴中碎屑沉积物的空间和体积分布，并在一个地细胞框架中离散化这些碎屑沉积物的空间和体积分布。洞穴底部沉积物类型的测绘得到了部分沉积物残渣阶地的局部地层测井和电阻率层析成像的补充。确定了四个电阻率组，并将其解释为低孔隙度和高孔隙度硅质碎屑沉积物，夹层大理石碎屑和主体岩石（大理石）。测量时沉积物的填充厚度范围为25 m至> 45 m；至少相当于被调查部分岩溶腔横截面的64–95％。这些观察表明，在某些情况下，异质硅质碎屑沉积物可以在岩溶系统中形成一个重要的体积成分，进而可以在源自类似岩溶系统的古喀斯特储层中形成重要的体积成分。这突出了在描述古喀斯特储层特征时，了解初始岩溶系统的背景，组织和发育的重要性。通常在洞穴调查期间不进行沉积物厚度测绘，主要侧重于记录人类可进入的开放腔。这意味着有关洞穴系统的形状和体积的调查数据，以及从中得出的统计数据，在应用于古喀斯特储层模型时应谨慎处理。