Platy limestone – geologic definition and its use as a mineral commodity

The main goal of the RoofOfRock project is to establish a joint platform for the sustainable use of platy limestone, its preservation and promotion, to create the relevant guidelines and to upgrade both individual and joint capacities in preserving this particularity of a common natural and cultural heritage along the karstified part of the Adriatic coast. The limestone was used as a primary building material throughout the whole project area and plays one of the most important roles in creating a common human history. This specific platy limestone as a basic construction material gives the Adriatic coastline and its interior its primary character. Therefore, the detailed geological investigation of platy limestone (e.g. its spatial extent, quality, etc.) serves as a basis for all other project activities.

The Geological Survey of Slovenia as the Leading Partner of the project is coordinating and managing the implementation of the project as a whole, while the institution has also coordinated the geological activities of Work Package (WP) 3 (Platy limestone – a geological definition and its use as a mineral commodity) in the entire project area and the prepared geological outputs for the project area in Slovenia. Hrvatski geološki institut – The Croatian Geological Survey (HGI-CGS) has contracts with all four Croatian RoofOfRock project partners: IDA, ZADRA, RERA SD, and DUNEA, to work on the project as an external expert, and to prepare the geological project outputs for the project area in Croatia. It comprises Croatian counties situated along the north-eastern coastal region of the Adriatic Sea. A general overview on building limestone was prepared for the whole region, while detailed investigations of PL focused only on selected areas of Istria (IDA), Zadar (ZADRA), Split-Dalmatia (RERA SD), and Dubrovnik-Neretva (DUNEA) counties. Hrvatsko rudarsko-geološko društvo Mostar – The Croatian Mining and Geological Society Mostar as an external expert has contracts with the Development agency of West Herzegovina county-HERAG project partner to implement the WP3 project measures in the project area of Bosnia and Herzegovina. The Department of Mathematics and Geosciences of University of Trieste (DMG-UniTS) project partner prepared the geological outputs for the project area in Italy.

The geological part of the project was divided into four different activities focused mainly on the characterization and identification of natural and physical properties of limestone along the Adriatic coast

The geological part of the project was divided into four different activities focused mainly on the characterization and identification of natural and physical properties of limestone along the Adriatic coast. The first set of working actions included an overview of the different types of building limestone occurring in the project area. The limestones were classified lithostratigraphically and by their use throughout history as well as by their potential as a mineral resource. The existing relevant documents and data were reviewed with the goal of preparing a list of the main types of building limestone and a list of the typical quarries. After the interpretation and harmonization of all the collected geological data, an overview geological map on a scale of 1:250,000 of the spatial occurrence of limestone in the project area was created. It has served as a basis for further studies of platy limestone. In addition, the presented geological units were assessed according to their potential as building limestone. The general characteristics and provenance of building stone used in autochthonous karst architecture was studied through 26 selected show-case objects. The most important tasks were more focused on platy limestone, a special type of building stone, most commonly used for roofing. Its geological definition is established and its extent within the project area is shown on a geological map on a general scale of 1:50,000. Various platy limestone horizons were identified through their major sedimentological and paleontological characteristics, stratigraphical position and age. Detailed geological mapping of selected areas as well as sedimentological and paleontological laboratory analyses were implemented. Finally, according to the recognized potential and spatial occurrence of platy limestone types they were evaluated as a mineral commodity with the final goal of identifying potential quarrying areas. Paleontological and sedimentological historical data on platy limestone and new data were evaluated from the point of view of natural heritage (cooperation with WP5) and some geo-sites were proposed. Geological data gathered were incorporated into the joint GIS-based database built within the framework of WP7.

Geologists, covering project areas in Italy (DMG UniTS), Slovenia (GeoZS), Croatia (HGI-CGS) and Herzegovina (HRGDM) actively cooperated in order to harmonize the geological data presented in an overview map (1:250,000) and maps of platy limestone occurrence. In the scope of WP3, several coordination meetings were organized to coordinate the implementation of geological (WP3) activities among all four countries. They were especially focused on the harmonization of maps, definition of procedures for show-case objects selection, preparation of data for the GIS database, the estimation of quality and the quantity of platy limestone and preparation of final outputs. During the process of selection and investigation of the show-case objects, we cooperated with the leaders of WP4-cultural heritage (FB6 UP ZRS). In order to set guidelines for the sustainable exploitation of platy limestone, geologists also collaborated with leaders of WP5 (FB5 DMG UniTS) and WP6 (FB7 JZ PŠJ).