## 2 Geological Settings  
The investigated area is located on the E side of the Peljesac Peninsula, which is part of the External Dinarides, an approximately 600 km long fold-and-thrust orogenic belt [17; 18; 19; 20; 21; 22; 23; 24]. The External Dinarides are geotectonically positioned along the NE margin of the Adriatic Sea, which corresponds with the NE part of the Adriic Microplate [18; 20; 23; 24; 25]. The Dinarides orogenic belt was uplifted during the Late Eocene to Oligocene, due to the Adria Microplate-European Plate collision [18; 19]. Most of the sediments in the External Dinarides were deposited during Mesozoic on the Adriatic Carbonate Platform from lower Jurassic to Upper Cretaceous [21; 22]. The total thickness of the sediments is estimated to a few kilometers (in places up to 8 km) [21]. During their geological evolution, Dinarides had a polyphase uplift, due to multiple compressional tectonic regimes that formed present tectonic settings of the area [17; 20; 21].  
The wider research area in the Peljesac Peninsula is composed of three stratigraphical and depositional units: Cretaceous carbonates, Paleogene carbonate, and clastic sedimentsand quaternary elastic sediments [26; 27; 28; 29; 30; 31] (Figure 1). Cretaceous carbonates are the dominant geological unit in the Peljesac Peninsula, and they are represented by limestones and dolomites subdivided into four chronostrigraphic units from Hauterivian to Maastrichtian age (Figure 1). Since the research area is composed of carbonates of Coniacian to Maastrichtian (K\({}_{2}\)\({}^{3-6}\)), they will be described in more detail. Upper Cretaceous carbonates are represented by thick-layered fossiliferous limestones and late diagenetic dolomites. Limestones are very fossiliferous, with remains of rudists and other mollusks, Echinorms, Bryozoans, Hydrozoas, and Foraminifera (Figure 2A-C,E). Lithofacies features indicate the deposition in the forereef environment with a substantial inflow of material from the nearby reefs [26; 27; 28; 29; 30; 31; 32]. On top of this lithofacies, there are thick series of vertical and lateral interchange of limestones and dolomites. Limestones are described as thick layers of mudstone and fenestral mudstones. The upper part of the unit is characterized by a higher dolomitization rate and gray to dark grey dolomites (Figure 2D,E). The interchange of limestones and late diagenetic dolomites results from irregular dolomitization, so there is a frequent lateral and vertical change in lithology. The youngest geological units in the area are foraminiferal limestones of the Eocene age. They are transgressive to the older deposits, usually Upper Cretaceous limestones [26; 27; 28; 29; 30; 31; 32] (Figure 1).  
Figure 1: Geological map of the research area (modified after [26]). Stress orientation according to [20; 27].  
Figure 2: Shows **(A)** Upper Cretaceous limestones with 0.5–1 m thick layers in the northern part of Peljesac Peninsula; **(B)** Mollusk fossil in the drillcore; **(C)** microphotograph of fossiliferous limestone lithofacies; **(D)** microphotograph of late diagenetic dolomite lithofacies; **(E)** polished drill hole core samples of different lithofacies: white samples are micrite limestones, light gray to gray are fossiliferous limestones with bioturbations; dark samples are late diagenetic dolomites.  
The Peljesac Peninsula is a relatively complex tectonic unit characterized by trusts, folds, and faults. Generally, it represents regional asymmetrical overturned anticline striking NW-SE. The core of the anticline contains the oldest, Lower Cretaceous deposits. The limbs are then composed of a succession of Lower Cretaceous to Paleogene sediments. Trusts are usually NW-SE striking with an inclination towards NE. These trusts are intersected by younger diagonal and transverse strike-slip faults. Our research area is placed in the SE limb of a regional anticline with NW-SE striking perpendicular to the maximal stress field (Figure 1).