Upper Cretaceous carbonate rocks in Jordan are the main resources for construction and paint-related industrial applications. This study evaluates the elemental composition, mineralogy, and petrography of two main geological formations from two localities in northern Jordan (Hallabat, Turonian age, and Ajlun, Santonian–Campanian age) to shed light on their composition, depositional environments, and potential industrial end uses. The elemental composition of the Hallabat Wadi Sir Limestone (WSL) Formation indicates notable variability between the middle and upper parts of the WSL carbonates in the area, with higher CaO content in the middle part (mean 55 wt.%) and higher silica content observed in the upper part (mean 2 wt.%) compared with the middle part (mean 0.9 wt.%). Meanwhile, analysis of the elemental composition of the Ajlun Amman Silicified Limestone (ASL) Formation indicates that the CaO content is relatively higher in the upper part (mean 56 wt.%). In addition, the lower part is more influenced by detrital input when compared with the upper part of the studied section, in contrast to the Hallabat WSL Formation. Petrographic analysis demonstrates that the WSL and ASL samples are predominantly micritic limestone. The XRD results for the Hallabat WSL and Ajlun ASL show that the mineralogical composition is dominated by calcite (CaCO₃). Statistical and PCA analyses also confirm these variabilities between the two sites, indicating that all samples from both sites were deposited under variable hydrodynamic and environmental conditions that affected their physical and chemical composition. The results show that all studied samples are in the range of pure limestone and can be used for specific industrial applications in addition to their current uses, including those in the pottery and porcelain ware, soda ash and caustic soda, steel industry, sugar, and textile production industries, thus contributing to the economic resources in Jordan.

The Danube – Tisza interfluve area in the middle part of the Carpathian Basin harbors numerous mainly groundwater-fed hypersaline (alkaline) ponds which were characterized by carbonate precipitation under varying geochemical, climatic, environmental conditions during the Holocene.  The formation of dolomite attributable to seasonal variations of the climate and concomitant volume, geochemical changes of the groundwater, and the waterbody in these lacustrine environments is a unique feature of the area. A general model of freshwater high magnesium calcite, proto-dolomite, and dolomite precipitation in these lakes has been constructed in the early-mid 1980s via the complex geological, geochemical isotope geochemical investigation of carbonate rocks of extant lacustrine sequences of the mentioned area complemented by geochemical analyses of the lake and groundwater. Seasonal and long-term climate variations are expressed in the form of macro and micro-cycles preserved in the rock record. These however have never been examined in detail.   To unravel and understand the cyclicity present in the mentioned carbonate sequences we need quantitative information on the composition and physical properties of rock. CT analysis of rocks yields data on density differences observable between the building blocks or forming components in the material under study. Groups identified via statistical analysis of the data can be assigned to the various rock-forming components, and these groups can be described quantitatively via statistical parameters characterizing distribution. 3D visualization of the clustered data in the rock samples allows for cross-validation of interpretations. Via studying the vertical and spatial heterogeneity of the identified rock-forming components using their descriptive statistical properties the presence of micro-and macrocycles can be revealed, which serve as a starting point for further investigations to understand the nature and causes of these cycles. We are to present the results of such work done on some carbonate samples of the mentioned area. Research has been carried out within the framework of the University of Szeged, Interdisciplinary Excellence Centre, Institute of Geography and Earth Sciences, Long Environmental Changes Research Team. Support of the Ministry of Human Capacities, Hungary Grants 20391- 3/2018/FEKUSTRAT and NKFIH 129265 are acknowledged.