Different types of laminae in a flowstone from La Cigalère Cave (Pyrenees, S. France)
Résumé
Due to its potential link with climate and seasonality, speleothem lamination has attracted growing interest in environmental studies. We report here different types of lamination analyzed in a flowstone from a high-altitude cave in the French Pyrenees. The aim of this research is to understand precisely the different mechanisms involved in the formation of the various types of laminae and to evidence the different parameters controlling their scaling, geometry and stacking pattern.
While aragonite and calcite form the main part of the flowstone, other minerals have been also identified at different scales (carbonates, oxides and hydroxides, sulfates). Post-depositional diagenesis, in particular aragonite-to-calcite recrystallization may either alter or emphasize the primary lamination. Lamination pattern include: aragonite-calcite first and second-order laminae, fluorescent laminae and geochemical laminae occurring either in aragonite or in primary calcite. These different types of lamination likely reflect fluctutation in dripwater chemistry and drip rates and thereby, are linked in some way to environmental changes within and outside the cave.