A multi-analytical approach applied to the archaeometric study of mortars from the Forty Martyrs rupestrian complex in Cappadocia (Turkey)

Abstract

Mortars and plasters from the Forty Martyrs rupestrian complex (Cappadocia, Turkey) were characterized by means of different and complementary analytical techniques, in order to achieve evidence about the raw materials and the production technologies employed in the site dwelled by some of the first Cappadocian Christian communities. The investigated area is constituted by rooms directly hewn in the volcanic deposits named "Fairy Chimneys" and included in the UNESCO World Heritage List. Archaeological studies attributed different uses to the rooms, i.e. chapels, storages and wineries. The multi-analytical approach means to confirm or to retract the archaeological thesis and to highlight probable differences in the production techniques of the stone materials. In this regard, textural and compositional data of the binder and the aggregate fractions were collected by optical microscopy and electron microscopy coupled with microanalysis. Pigments and binder composition were investigated by Fourier transform infrared and micro-Raman spectroscopy. Lastly, probable traces of organic residues were identified by gas chromatography coupled with mass spectrometry. The obtained results allowed for identifying variations in the technical and compositional characteristics of mortars and plasters which can be related to different uses of the rooms constituting the rupestrian complex