SpeleoDisc: A 3-D quantitative approach to define the structural control of endokarst: An application to deep cave systems from the Picos de Europa, Spain

• SpeleoDisc: a new method to establish the structural control of endokarst.
• The influence of major and minor structures is considered in 3-D.
• SpeleoDisc estimates the percentages of endokarst forced by massif discontinuities.
• SpeleoDisc compares cave surveys and discontinuities by stereographic projection.

The influence of geological structure on endokarst can be studied by establishing the relationships between discontinuities (faults, joints and bedding) with a cave survey. The cave survey elaborated by speleologists represents the directions and inclinations of the cave conduits and can be compared to the strike and dip of the discontinuities of a karst massif. This paper proposes a methodology, the SpeleoDisc method, which is effective in defining the structural control of the endokarst. The method has been designed and applied in a pilot area from the alpine karst massif of the Picos de Europa, where long and deep cave systems are well developed, including more than 360 km of conduits in its entirety. The method is based on the projection of cave surveys on geological maps and cross-sections and the comparison between the direction and inclination of the cave survey data and the geometry of the massif discontinuities in three spatial dimensions (3-D). The SpeleoDisc method includes: 1) collection and management of topographic information; 2) collection and management of cave data; 3) definition of the groups of conduits; 4) elaboration of geological maps and cross-sections; 5) collection of discontinuity data (bedding, faults and joints); 6) definition of groups of discontinuities; and 7) comparison between the cave conduit groups and the families of discontinuities. The SpeleoDisc method allows us define the influence of the major and minor structures on the caves geometry, estimating percentage of caves forced by each group of massif discontinuities and their intersections in 3-D. Nevertheless, the SpeleoDisc approach is mainly controlled by 1) the amount and quality of the cave survey data and 2) the abundance of cave deposits covering the conduit, which can mask the original geometry.