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Abstract UDC 911:551.44(450)
Antonio Pagliara, Jo De Waele, Paolo Forti, Ermanno Galli & Antonio Rossi: Speleothems and speleogenesis of the hypogenic Santa Barbara Cave System (South-West Sardinia, Italy)
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 EDAX analysis, suggest them to be related to variations in the depositional environment inside the cave, which in turn are probably correlated to external climatic oscillations.
Keywords: cave morphology, speleothems, mineralogy, aragonite-calcite banding, speleogenesis.
Izvlecek UDK 911:551.44(450)
Antonio Pagliara, Jo De Waele, Paolo Forti, Ermanno Galli & Antonio Rossi: Sige in hipogena speleogeneza jamskega sistema Santa Barbara (JZ Sardinija, Italija)
Clanek predstavlja rezultate raziskav speleogeneze, sig in sekundarnih mineralov v jami Santa Barbara v rudnem obmocju Iglesiente na jugozahodni Sardiniji (Cagliari). Jama je razvita v kambrijskih karbonatih, pri cemer je vecina glavnih rovov pa nastala v hipogenih pogojih. V obdobju med kambrijem in holocenom lahko razberemo devet speleogenetskih faz. Opticne in uklonske analize sig kazejo na izmenjajoce se plasti kalcita in aragonita. Teksturne in kemicne znacilnosti sig smo raziskovali z vrsticnim elektronskim mikroskopom in elektronskim mikroanalizatorjem. Ugotovljene lastnosti so pogojene s sedimentacijskim okoljem v jami, ki pa je povezano s klimatskimi spremembami na povrsju.
Klucne besede: jamske skalne oblike, sige, mineralogija, kalcitno-aragonitni pasovi, speleogeneza.
INTRODUCTION
Santa Barbara show cave (SBC1) is a well known tourist attraction and is estimated to be one of the oldest caves in Italy (Forti & Perna 1982). It is one of the most famous "mine caves" of Italy discovered in 1952 by excavations at level 195 m a.s.l. in the San Giovanni Mine (Iglesias, Sardinia) (Forti et al. 2005). After the closure of the mines this area became part of the 'Parco Geominerario della Sardegna' (Geomining Park of Sardinia), included in the...