Speleothems and speleogenesis of the hypogenic santa barbara cave system(south-westsardinia, Italy)

Abstract

This paper presents the results of a study on the speleogenesis and the speleothems and secondary mineralisations of the Santa Barbara Cave System in the Iglesiente Mining District (South-West Sardinia, Cagliari). This cave system, hosted in Cambrian carbonate rocks, has a very long geological history and its main voids have formed in hypogenic conditions. Nine speleogenetic phases can be recognised ranging in age between Cambrian and Holocene. Optical microscope and diffractometric analysis of active flowstone deposits have shown them being composed of alternating calcite and aragonite layers. The textural and chemical characteristics of these layers, obtained by SEM and EDAXanalysis, suggest them to be related to variations in the depositional environment inside the cave, which in turn are probably correlated to external climatic oscillations.