This study assesses the static stability of the artificial Sabereebi Cave Monastery southeast of Georgia's capital, Tbilisi. The cliff into which these Georgian-Orthodox caverns, chapels, and churches were carved consists of a five-layered sequence of weak sedimentary rock—all of which bear a considerable failure potential and, consequently, pose the challenge of preservation to geologists, engineers, and archaeologists. In the first part of this study, we present a strategy to process point cloud data from drone photogrammetry as well as from laser scanners acquired in- and outside the caves into high-resolution CAD objects that can be used for numerical modeling ranging from macro- to micro-scale. In the second part, we explore four distinct series of static elasto-plastic finite element stability models featuring different levels of detail, each of which focuses on specific geomechanical scenarios such as classic landsliding due to overburden, deformation of architectural features as a result of stress concentration, material response to weathering, and pillar failure due to vertical load. With this bipartite approach, the study serves as a comprehensive 3D stability assessment of the Sabereebi Cave Monastery on the one hand; on the other hand, the established procedure should serve as a pilot scheme, which could be adapted to different sites in the future combining non-invasive and relatively cost-efficient assessment methods, data processing and hazard estimation.

This paper analyses the mineralogical composition, texture, and structure of a stalactite sampled from the city-wall storerooms of the Nueva Tabarca fortress (southeast Spain). This speleothem presents an uncommon mineral assemblage: aragonite, brucite, gypsum, silica, and halite. Internally, it shows complex structure: (1) a central soda-straw composed by aragonite; (2) an external puff-pastry cone-crust formed preferentially by aragonite and brucite; and (3) an internal branching of coralloids, showing a subtle layering between brucite and aragonite. Gypsum, halite, and silica locate in the outer coating of the cone-crust. The sequent mineral precipitation sequence has been established: aragonite > brucite > gypsum/silica > halite. Speleothem formation is directly related to the chemical weathering of the rocks and mortars used as building materials of the city-wall. Brucite precipitates has been always linked to the presence of MgO-based geomaterials. However, the lack of these compounds as building materials in Nueva Tabarca fortress makes this investigation a unique example of brucite precipitation. PHREEQC calculations showed that interaction between pore waters and the minerals of mortar aggregates (dolomite, pyroxene, and amphibole) leads to rich-magnesium solutions. Evaporation modelling of lixiviated waters describes the precipitation of the mineral assemblage of the brucite-aragonite speleothems.

En este trabajo se propone una nueva metodología, basada en microtomografía de Rayos X y Análisis Digital de Imagen, para el cálculo de tasas de alteración de rocas a partir de breves periodos de exposición directa al ambiente. Se han estudiado dos rocas carbonatadas porosas (una calcarenita y una calcirrudita con porosidad media del 20%), expuestas durante un año a un clima Mediterráneo semiárido costero (Nueva Tabarca, Alicante). Las microtasas obtenidas indican una mayor velocidad de alteración en la calcirrudita (18.75 mm/ año) que en la calcarenita (9.13 mm/año). Esta variación se justifica por las diferencias en el sistema poroso de cada roca y su influencia en la efectividad de los procesos de alteración habituales en climas semiáridos costeros. Además, los resultados obtenidos validan la metodología planteada, la cual constituye un importante avance en el estudio de la velocidad de deterioro de materiales, permitiendo de una forma rápida y cuantitativa, analizar la vulnerabilidad de las rocas a determinados ambientes de exposición.

A multiproxy methodology has been employed to characterise two granite anchors discovered on the seabed near the island of Nueva Tabarca (Alicante, Southeast Spain). According to the significant archaeological context where they were found, the studied anchors can be dated from the Roman ages (late Republican period). One of the most interesting aspects is the absence of regional geological outcrops with rocks compatible with the granite used in the production of the anchor, which shows a foreign origin consistent with the connection of the anchor to maritime transport across the Mediterranean Sea. The lack of precise information about the artifact’s origin underscores the interest and need for the application of petrological techniques to determine its provenance. The methodology utilised encompasses five distinct techniques: (1) non-destructive textural analysis using X-ray microcomputed tomography; (2) K–Ar dating; (3) petrological characterisation through optical microscopy; (4) geochemical characterisation using X-ray fluorescence and atomic absorption spectrometry. The results allow for a comparison of the anchor rock’s characteristics with various granite outcrops along the Mediterranean coasts (Eastern, Central, and Western sectors), suggesting potential source areas based on petrological compatibility with the material under study. The findings point to the origin of the Nueva Tabarca granite anchor being granite outcrops in Southern Italy (Calabria), reinforcing the connection between the Spanish southeastern coasts and Southern Italy. These results highlight the utility and significance of multiproxy petrological methodologies in the geoarchaeological study of decontextualised artifacts.