Lower Jurassic succession at the site of potential Roman quarry Staje near Ig (central Slovenia)

Abstract

Several locations along the southern margin of the Ljubljana Moor have been proposed as sites of antique Roman quarries, but except for the site in the village of Podpeč, no detailed sedimentological investigations, which would reveal the spectrum of available natural stone, have yet been made. This paper presents a section logged at the potential Roman quarry from the small valley southeast of the village of Staje near Ig. The section is composed of Sinemurian strata dominated by micritic limestone with dissolution voids and bioclastic limestone, mostly wackestone with mollusks. Other facies are rare aggregate-grain/ooidal calcarenite, lumachella, limestone microbreccia, and stromatolitic limestone. Altogether, 21 microfacies types are described. Facies association points to sedimentation in restricted and open marine lagoon repeatedly subjected to emersion, rarely high-energy conditions or events. Previously unrecorded on the Dinaric Carbonate Platform in this area are neptunian dykes that occur as fractures partially filled by calcite cement and partially by intra/bioclastic packstone containing upper Jurassic microfossils. These could potentially serve as a diagnostic feature for recognizing artefacts made from stone quarried at Staje.