Pleistocene Pisolites as Archives of Hydrological Variability in Mediterranean Coastal Environments: Evidence from Eivissa (Balearic Islands, Spain)

Pisolites are coated carbonate grains whose nucleus–cortex architecture may preserve evidence of changing hydrological conditions, yet their palaeoenvironmental significance remains poorly explored in Pleistocene Mediterranean coastal successions. This study investigates pisolite-bearing horizons from Eivissa (Balearic Islands, western Mediterranean) using field sedimentology, quantitative morphometry, petrography, and X-ray diffraction (XRD). The pisolites occur within fine-grained carbonate-cemented horizons associated with palaeosols and stabilized coastal dune systems, including interdune settings. Morphometric analysis of two closely spaced samples from the same Cala Compte horizon shows significant differences between matrix-associated and isolated fractions in maximum pisolite and nucleus diameters, while cortical thickness differs significantly only in CC2. Petrography reveals successive, locally discontinuous, asymmetric, and variably concentric cortexes, indicating polyphase accretion. XRD shows calcite-dominated pisolites and matrices with subordinate brushite, quartz, and minor unidentified phases. Integrated evidence supports local to near-local formation with limited redistribution under recurrent changes in water availability. The Eivissa pisolites therefore record episodic hydrological variability and polyphase carbonate formation during phases of Pleistocene coastal landscape stabilization.