Naslov
An overview of tectonic evolution of the Plitvice Lakes National Park based on structural data

Autori
Krnjak, Helena ; Matoš, Bojan ; Pavičić, Ivica ; Barudžija, Uroš ; Vlahović, Igor ; Lužar-Oberiter, Borna

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, prošireni sažetak, znanstveni

Izvornik
6. hrvatski geološki kongres s međunarodnim sudjelovanjem: Knjiga sažetaka = 6th Croatian Geological Congress with international participation: Abstracts Book / Horvat, Marija ; Matoš, Bojan ; Wacha, Lara - Zagreb : Hrvatski geološki institut, 2019, 110-111

ISBN
978-953-6907-73-1

Skup
6. hrvatski geološki kongres s međunarodnim sudjelovanjem

Mjesto i datum
Zagreb, Hrvatska, 09.10.2019. - 12.10.2019

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Plitvice Lakes National Park, Dinaridic tectonic phase, compression/transpression, neotectonics, structural beach ball diagrams

Sažetak
The Plitvice Lakes National Park (NP) represents a part of the Karst Dinarides, a NW–SE oriented orogenic system parallel to the NE Adriatic coast, formed due to the collision of the Adria Microplate and European Plate during the Eocene and Oligocene. Accommodated collision formed a fold and thrust belt composed of a c. 7 km thick sediment succession (mainly carbonates) deposited on the Adria Microplate during Palaeozoic to Cenozoic time (Vlahović et al., 2005). Available data on the present-day stress field show that N- to NNE-directed convergence between European and Adriatic plates is still an ongoing process (average movement between 3 and 4.5 mm/year ; Grenerczy et al., 2005), being a driving force for the differential distribution of horizontal shortening, i.e. compression and transpression in the Dinarides (D’Agostino, 2008 and references therein). In 2017, the Plitvice Lakes NP initiated a three-year project to improve existing knowledge on the tectonostratigraphic evolution, palaeogeography and Quaternary evolution of the Plitvice Lakes area. In order to evaluate and improve knowledge on the tectonic models and structural framework of the study area a detailed structural investigation was performed within the Mesozoic carbonate units. Structural investigation conveyed detailed outcrop-scale structural analysis, i.e. structural measurements of strata orientation and fault planes as well as determination of the fault kinematics. During the investigation at 297 sites within the study area 103 measured fault plane data, 250 strata orientation data as well as some overlapping and cross-cutting relations have been collected. On the basis of structural investigation it may be concluded that measured strata orientation in the Plitvice Lakes NP indicate on an asymmetric anticline structure with dominant homoclinal SW limb where strata gently dip (≤20°) towards SW, whereas in the anticline hinge zone (i.e., Plitvice Lakes “sensu stricto”) and its steeper NE limb structural measurements pinpoint to strata dipping both towards SW and NE (at angles ≥35°). In the same time, measured and computed fold axial planes are dominantly subvertical and/or steeply dipping towards SW, with characteristic Dinaridic strike (e.g., 135–315°), being associated to the Dinaridic tectonic phase, i.e. NE–SW trending compression. Measured fault plane data within the Cretaceous and Triassic carbonate deposits in the study area may be subdivided into six kinematically compatible fault groups (Fig. 1). These fault groups may reflect three kinematic phases corresponding to the existing structural model of the tectonic evolution of the Dinarides. The oldest fault kinematic groups are characterized by NW-SE striking fault dataset, which indicate NE–SW trending compression in the study area. Although measured fault planes (Fig. 1A-I and 1B-I) mostly show typical SW-vergent Dinaridic fault structures, in the area of the Plitvice fault NE-vergent reverse fault planes are more common. In the same time, based on observed cross-cutting relations in respect to the older reverse faults ; the younger fault kinematic groups in the study area convey NW and NE-striking dextral and sinistral fault planes (Fig. 1A-II and 1B-II). Observed traspressional/transtensional structures are associated to both NE- and NW-trending transpression/transtension in the area, which probably correlate to the repeated change of the stress field in the post-Dinaridic tectonic phase, i.e. during the Neogene and Quaternary, with tectonic movements along both structurally reactivated and newly formed fault planes. The least observed fault planes in the study area are characterized by NW-SE striking normal fault planes (Figs. 1A-III and 1B-III) indicating NE–SW trending extension within the study area. Though cross-cut relations of normal faults in respect to reverse and strike-slip faults were not observable in the study area, existing kinematic models of faulting in the fold hinge zones (Tavani et al., 2012) suggest that extensional structures in the fold hinge zone are probably associated to differential stress distribution and accordingly convey extension through collapse perpendicular to the fold's axial plane. Structural investigation presented here is in agreement with the existing tectonic models of the Dinaridic evolution, although collected structural data in the area of the Plitvice Lakes NP indicate existence of a gentle, large-scale asymmetric NE-vergent anticline above the SW-dipping thrust fault (Plitvice fault), which due to densely fractured Cretaceous and Jurassic carbonates in the fault’s hangingwall, enabled substantial erosion in the fold hinge zone and formation of the Plitvice Lakes system in the remaining impermeable Triassic dolomites.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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