Effective porosity in carbonate rocks from the Betic Cordillera (southern Spain): A regional dataset for reservoir and aquifer characterization

Study region The Betic Cordillera (southern Spain) comprises carbonate formations ranging from Paleozoic to Cenozoic age, distributed across the Internal, Subbetic, and Prebetic domains. These include metamorphic marbles as well as non-metamorphic limestones and dolostones deposited in contrasting tectonostratigraphic settings. Study focus This study compiles and statistically characterizes 866 laboratory-measured effective (open) porosity values from carbonate rocks of the Betic Cordillera. Porosity was determined following the UNE-EN 1936:2007 standard. The dataset shows a strongly right-skewed distribution, with porosity values ranging from 0.03 % to 36.8 % and a median of 1.5 %. Porosity magnitude and variability systematically increase toward younger stratigraphic units. New hydrological insights The lowest porosity values are associated with Internal Zone metamorphic marbles and the Middle–Late Jurassic Ammonitico Rosso Formation, whereas the highest porosities occur in Upper Cretaceous and Cenozoic carbonates. A statistically significant inverse linear relationship between apparent (bulk) density and effective porosity is observed for both limestones and dolostones, supporting the use of bulk-density data as a first-order regional proxy for porosity estimation. The compiled database provides first-order constraints relevant to the matrix-controlled hydraulic behavior of Betic carbonate aquifers and supports preliminary, screening-level assessments of subsurface storage capacity. The applicability of the dataset is limited to regional-scale analyses and does not account for fracture or conduit permeability. Despite these limitations, the dataset contributes to groundwater-resource assessments, preliminary screening of geological formations for CO₂ and H₂ storage, and evaluations of durability in carbonate dimension stones.